Extraction of molybdenum from sulphide materials containing molybdenum by means of biological leaching in presence of iron
SUBSTANCE: method involves stages of (a) material interaction with acid leaching solution in presence at least of one iron compound and acidophilic microorganisms at least capable of oxidating ferrous iron, and (b) leaching. Leaching stage (b) is performed at control of molar ratio of dissolved ferric iron to dissolved molybdenum and it is assumed equal at least to 6:1, preferably at least to 7:1 and after leaching there performed is stage of (c) molybdenum extraction at least from one solid and liquid residue of the leaching process. Finally, molybdenum is extracted from leaching residue of leaching process. Final degree of Mo extraction from sulphide material containing molybdenum is 89%.
EFFECT: effective molybdenum extraction from sulphide material containing molybdenum.
24 cl, 21 dwg, 9 tbl, 10 ex
The technical FIELD
The present invention relates to a process for recovering molybdenum from containing molybdenum sulfide material. The material is injected into the interaction with the leach solution in the presence of iron compounds and oxidizing acidophilic iron microorganisms, followed by leaching with regulation molar ratio of dissolved ferric iron to dissolved molybdenum. It is preferable to use a high concentration and molar excess dissolved iron. In conclusion, the molybdenum is extracted from the remainder of the leach solution used in the leaching process.
The LEVEL of TECHNOLOGY
The need of the global industry in molybdenum is great, especially in metallurgy. Steel, cast irons, super alloys and alloys for welding are important containing molybdenum end-products having high strength, impact resistance, wear resistance and corrosion resistance. Important applications not related to metallurgy, include use as lubrication and catalysts in the refining, pigments for paints and dyes and application in chemistry in combustion inhibitors and additives that reduce the smoke.
Molybdenite (MoS2) is the main mineral source is olindina. Ore containing molybdenite, can be extracted from primary ores which are mined molybdenite. This main ore is widely distributed and is often found in small veins or disseminated in the form of small grains and is often associated with granites, pegmatites or copper sulfides. Therefore, the molybdenite is often a by-product during the extraction of copper. After operations of milling and flotation of copper sulfides form a concentrate, which is additionally subjected to mechanical treatment and receive flotation of molybdenite concentrates. After numerous stages of grinding and flotation can lose up to 50% of the molybdenite. The content of molybdenum in these concentrates is about 45%. This low output is especially inadequate to meet modern needs. In addition, the processing of these concentrates with modern pyrometallurgical technologies leads to undesirable environmental pollution and high costs of energy.
One group of technologies that are currently being developed and in some cases are used in the production, is an Association of biological technologies for the extraction of metals from ores or enriched concentrates. To describe different but related technologies used two terms: biological oxidation and biologists is a mini-leaching. Both terms refer to the stimulated microorganisms decomposition of minerals on the basis of sulphides. It is a biochemical process that involves a complex interaction between microorganisms, leaching solution and the surface of the mineral. The term "biological oxidation" is usually used to describe stimulated by microorganisms in the oxidation of minerals, such as pyrite (FeS2) and arsenopyrite (FeAsS). Usually the problem is not the removal of iron and arsenic from sulphides, and the decomposition and removal of these minerals, because they contain included refractory noble metals such as gold. Biological oxidation of pyrite and arsenopyrite in refractory gold ores used on an industrial scale using large quantities of poor ore and reactor with stirring for concentrates. After the biological treatment of the gold extracted by conventional leaching technologies. On the other hand, biological leaching means the same basic microbiological process, but with the alternative task of extracting solubilizing metal-containing sulfide mineral.
Therefore, in the case of cobalt pyrite biological leaching is used in industrial scale for the extraction of cobalt, interspersed in a matrix of pyrite crystal. The crust is ASEE time biological leaching is used in many countries for the extraction of copper from copper-containing minerals, such as chalcocite (Cu2S) and covellite (CuS). Biological leaching is also used on an industrial scale to obtain uranium and processing of sulphide Nickel and zinc is carried out in semi-industrial scale.
I believe that the sulphides of metals decompose on competitive reactions going without biological mediation, such as the oxidation of sulfide with Fe(III), or through mediated by enzymes influence on the crystal structure of the sulfide. In the microbiological literature they are called "indirect" and "direct" mechanisms, respectively. Recently been updated and combined features classical descriptions (Schippers and Sand (1999) Appl. Environ. Microb. 65, point of 319-321) and proposed two different specific minerals indirect mechanism: 1) thiosulfate mechanism (for example, related to FeS2, MoS2and WS2and 2) polysulfide mechanism (for example, ZnS, CuFeS2and PbS). In the context of this publication uranyl ions of iron(III) chemically affect the water-insoluble sulfides of metals, pyrite and molybdenite, and then oxidize the formed sulfate in sulfuric acid. Efficiency, are likely to be significantly increased extracellular polymeric substance produced by the cells, which promotes adhesion of cells to the surface of the mineral and the formation of complexes with Fe(III) and their con is interobang at the interface metal/cell. When using mixed populations of microorganisms to use multiple strategies leaching.
Significant progress has been made in the identification of different microbial populations capable of promoting the decomposition of sulphides of metals by means of the processes of biological oxidation or biological leaching. In General, these populations are called extremophiles, because their normal environment can be characterized as containing a metal with a dilute solution of sulfuric acid. Bacteria, typical mesophilic temperature regime (20-42°C), along with other include from acidithiobacillus ferrooxidans, A. thiooxidans and Leptospirillum ferrooxidans. Taxonomically separate group of Archaea may be represented by one or more strains of Ferroplasma, such as F. acidiphilum. Moderate thermophile, for example Acidithiobacilllus caldus, Sulfobacillus acidophilus, S. thermosulfidooxidans and Acidimicrobium ferrooxidans, can prevail with further increase in temperature to about 55°C. In the environment leaching at temperatures up to 65°C or slightly above can prevail extreme thermophile that include additional representatives of Archaea, such as Acidianus brierieyi, Metallosphaera sedula and Sulfolobus metallicus.
Since oxidation of the metal sulfide include electrochemical component, to systems of biological leaching important acyclical the reduction potential, or redox potential. Although more precise technical approach should include mixed potential (corrosion) of sulfide minerals during oxidation, which contribute to the microorganisms, more convenient and practical is the tracking of the working indicator, as the redox potential of the solution. The redox potential is mainly influenced by the molar ratio of the amount of Fe(III) to the amount of Fe(II) in solution and can be represented by using the Nernst equation and in the field and in the laboratory can easily be measured using a probe. For the high redox potential requires a large part in the solution of iron represented the Fe(III), and the primary ion is actually the uranyl Fe(III). In both mechanisms the population of microorganisms regulate the redox potential by cyclic oxidation of ferrous iron to ferric iron as its consumption in the reaction with sulfide mineral. However, not all of oxidizing iron strains found in similar environments, capable of delivering extremely high redox potentials, because they are suppressed at high concentrations of Fe(III). For example, it is known that iron oxidizers, such as Leptospirillum ferrooxidans can multiply rapidly at much higher potentials than from acidithiobacillus ferrooxidans.
Some sulfides of metals, including chalcopyrite (CueS 2and molybdenite, in varying degrees-resistant bacteria and at the present time is particularly stable molybdenite. First of all, it is established that the kinetics of leaching of molybdenite is unsatisfactory. The data available on low rate of biological oxidation of molybdenite show that for acceptable speeds biological oxidation may require small particles and hence large surface area. In addition to the crystal structure and the specific electronic configuration noted that the value of the ion product of molybdenite leads to the conclusion about the stability of molybdenite to leaching. Despite these considerations, the observed resistance, probably partly due to the availability of high redox potential or, in other words, the high activity of oxidizing iron microorganisms in the presence of toxic molybdate ions. As shown in the publication Romano et al. (2001) FEMS Microbiology Letters 196, 71-75, this is difficult to achieve in biological leaching. Unlike other hard-to-treat sulfides, such as chalcopyrite, for a study which applied a lot of effort over the last approximately 50 years, there has been only a small number of studies biological wimalasiri the molybdenite. Until the present invention, the leaching of industrial material normally encountered conditions was considered impractical.
In the publication Tributsch and Bennett (1981) J. Chem. Technol. Biotechnol. 31, 565-577, studied the extraordinary stability of molybdenite to bacteria and chemical oxidation. It is shown that the molybdenite are not protons, but are ferric ions, albeit very slowly. The molybdenite is not suitable for bacteria source of energy, but he slowly recovers Fe3+added to cultures of T. ferrooxidans containing molybdenite, which leads to increased growth of microorganisms due to oxidation of Fe2+.
The literature describes attempts to overcome the toxic effect of molybdate on the populations of microorganisms, leaching the ore. In the publication Duncan et al. (1967) AIME Transactions 238, 122-128, the study of adaptation. Mesophilic leaching bacteria Thiobacillus ferrooxidans (now from acidithiobacillus ferrooxidans) are slow to adapt when 6 consecutive transfers in the environment with increasing concentration, which leads to growth, albeit from a low speed, when the molybdenum content of 90 million-1.
Recently in the publication Nasernejad et al. (2000) Process Biochemistry 35, 437-440, used a similar technique, in this case, spent 15 consecutive hyphens in the environment with con what intracies of ammonium molybdate from 1 million -1to a final concentration equal to 15 million-1. The molybdenum sulfide was oxidized by the microorganism I. ferrooxidans in the leaching solution, representing 0,9K solution of inorganic salts containing 0.9 g/l Fe as ferrous sulfate. Although the final yield was approximately 93%, the method consisted of several stages of washing with hydrochloric acid and carbon disulfide, respectively, and weekly replacement of barren environment to reduce the inhibition of microorganisms, which corresponds to the maximum concentration, equal to about 800 mg/l Mo.
In the publication Brierley and Migg (1973) Science 179, 488-490, described the use of thermophilic microorganism at a temperature of 60°C for biological leaching. The microorganism, currently known as Acidianus brierleyi, showed higher resistance to Mo than mesophilous, and grew at a concentration of Mo in solution, equal to 750 mg/L. Respiration in the absence of growth occurred until the concentration of Mo, equal to 2000 mg/l (Brierley, 1973, J. Less Common Metals 36, 237-247). However, for the 30-day period, the molybdenum was solubilizers only to output, equal to 3.3%. Add 0.02% yeast extract and 1% ferric sulfate increased the output to 13.3%, but remained unclear, could trivalent iron to have any protective effect, and not only contribute to the indirect leaching.
From the party who entered previously in the publication Bryner and Anderson (1957) Ind. Eng. Chem. 49, 1721-1724, data it is known that the number of the resulting dissolved molybdenum was increased when pyrite and molybdenite biologically videocialis together, indicating that the effect of soluble iron on enhanced biological oxidation of molybdenite. However, the authors found a certain optimal concentration of ferrous iron, 4,000 million-1, which provided the extract 140 mg of soluble molybdenum from 5 g of molybdenite concentrate. In addition, it was shown that the amount of leached substances is proportional to the particle size. However, consideration of the above documents shows that neither the output nor the resistance to molybdenum does not grow to an economically acceptable level.
In the publication Karavaiko et al. (1989) in Salley et al. (eds.) Proc. Int. Symp. CANMET SP 89-10, 461-473, the data on limiting concentrations of dissolved Fe and Mo in the iron-containing (9K) environment with the growth of T. ferrooxidans and oxidation of ferrous iron. Molybdenum and ferrous iron are present in the liquid phase, and in the sediments in amounts that depend on their concentration and quantity of inoculum. The deposition of Mo(VI) practically does not occur at pH 2.4 to 2.5 if its initial concentration exceeds 250 mg/l and trivalent iron begins to precipitate in the presence of 750 mg/l Mo(VI). Limited solubility leads to EF the objective concentration of trivalent iron, equal 2443 mg/l, adding 30% inoculum to the culture medium, which corresponds to the portable microorganisms concentration equal to 500 mg/l Mo(VI). 20% inoculum corresponds to the portable microorganisms concentration of ferric equal 1675 mg/l, and Mo(VI), equal to 150 mg/L. Although the authors suggested the presence of influence of trivalent iron to the increased stability of T. ferrooxidans due to the formation of chelates and partial deposition of Mo(VI), an important role in protecting attributed to the amino acids forming the joint complexes with iron-molybdenum. Adaptation of T. ferrooxidans to Mo and other heavy metals is attributed to the selection of mutants, characterized by increased synthesis of chelate exometabolites (amino acids). The authors suggest that the reduction of toxic effects due to the formation of chelates or deposition may depend on the composition of the medium.
The use of chemicals leach solution for the regulation of toxic effects of ions leached from the ore, it is important for other applications biological leaching. For example, in the publication Sundkvist, Sandström, Gunneriusson and Lindström (2005) Proc. 16thInternational Biohydrometallurgy Symposium, D.E.Rawlings and J.Petersen (eds.), 19-28, it is shown that the toxic effects of fluoride on microorganisms for biological leaching can be minimized by adding aluminum to salaciously solution.
The PRESENT INVENTION, AND VARIATIONS in ITS IMPLEMENTATION
None of the methods of the prior art has failed to provide adequate solutions to the problem of efficient extraction of molybdenum from solid materials technology using microorganisms. The present invention describes the use of technology biological leaching in an effective and economical way of using molybdenite and/or related containing molybdenum sulfide materials for the extraction of molybdenum, where this method allows the processing of low - and high-grade raw material with high efficiency from the point of view of speed and output.
The present invention solves this task according to the point 1 of the claims. Additional claims describe preferred embodiments of. The present invention relates to a process for recovering molybdenum from containing molybdenum sulfide material, which comprises the following stages:
(a) interaction containing molybdenum sulfide feed material with an acidic leach solution in the presence of at least one compound of iron and acidophilic microorganisms, at least, able to oxidize ferrous iron,
(b) conducting the leaching when regulated and molar ratio of dissolved ferric iron to dissolved molybdenum and
(c) extraction of molybdenum from solid and/or liquid residues leaching process.
The basis of the method of leaching is control of the molar ratio of dissolved ferric iron to dissolved molybdenum. When choosing the absolute amount of trivalent iron and, consequently, his relationship amount to the amount of dissolved molybdenum trivalent iron modifies toxic effects and protects the microorganisms used for leaching. Disastrous effects of hexavalent molybdenum leach ore bacteria are eliminated to concentrations of molybdenum, equal to 4.4 g/l To protect cells from the toxic effects of Mo does not require organic metabolites (i.e., amino acids)as the reagent ferric sulfate added to the culture solutions, provides microbial growth and oxidation of iron at high concentrations of Mo in solution. It should be understood that the leaching occurs in conditions where iron and molybdenum can be dissolved even at high concentrations. Such large quantities of trivalent iron can be achieved through the activity of oxidizing iron acidophilic microorganisms. If the iron is to extract optional, the term "biological leaching" can what about the correct use for the oxidation of molybdenite or pyrite, conducted in the present invention, because iron is not only used as a chemical oxidant, and when re-oxidation to maintain a high redox potential necessary for effective leaching, in addition, the oxidizing agent also plays a decisive role in the formation of complex molybdate and minimize toxic effects to populations of microorganisms.
In the beginning use a material comprising a sulfide containing molybdenum. When used in the present invention, including the appended claims, the terms in the singular shall include the terms in the plural, unless the context clearly requires otherwise. Thus, reference to "a sulfide containing molybdenum includes one sulfide or a mixture of sulfides.
The material can be obtained from ores, minerals, catalysts, and wastes, but is not limited to only them. For the method corresponding to the present invention, the material may be raw or before the subsequent processing may be subjected to one or more stages of pre-processing. For example, suitable methods of pre-treatment, known to experts in the art, may include drying, grinding, dispersing and/or biological leaching. Preliminary RA is supposedly recommended to ensure that the specified average particle size, which affects various process parameters, including agglomeration, interaction with microorganisms, the surface area (directly affects the rate of biological leaching), permeability to gases and leach solution, etc. But containing molybdenum sulfide material can be used in the way in the form of a stationary layer or mist mainly depending on the desired configuration of the reactor. The solid material is preferred to dumps or landfills, while suspended facilitates transactions in the reactor with stirring.
In the context of the present invention the ore material is often a mixture of minerals, including, for example, but not limited to, molybdenite, pyrite, chalcopyrite and/or bornite. Preliminary leaching may be required, in particular, to reduce the content of copper sulfides and to reduce competition for ferric iron in the leach solution between the sulphides of copper and molybdenum, which ensures the maintenance of high redox potential of the solution.
Leach solution of the present invention is defined as an acidic solution of ferric sulfate with the addition of nutrients that stimulate cell growth, in particular the propagation of oxidizing iron microorganisms when added to solid sireuil in suspension. For example, the leaching solution contains nutrients in the form of, but not limited to, ammonium sulfate, heptahydrate of magnesium sulfate and potassium dihydrophosphate in suitable concentrations.
Chemolithotrophic microorganisms are able to use inorganic electron donors as sources of energy. In the present invention such energy sources for populations of microorganisms include sulfide minerals, including, but not limited to, pyrite, molybdenite and chalcopyrite and related minerals, as well as elemental sulfur, sulfur compounds in the intermediate States of the autocatalytic oxidation and re-oxidation of Fe(II) Fe(III) in solution. Sufficient aeration, since oxygen is the preferred final electron acceptor for the enzyme biological oxidation of iron compounds and sulfur, and carbon dioxide is absorbed by the microorganisms as the main source of carbon for growth. The preferred iron compounds are sulfide, ferrous iron and/or sulfate ferrous iron. Ferrous iron can be added to the leaching solution. Alternative sulfate ferrous iron can be formed by oxidation of the sulfide, ferrous iron, or by the reaction of trivalent glands is with sulfides of other metals. Microbiological oxidation obtained ferrous iron in solution leads to the production of trivalent iron, these compounds of trivalent iron and represent compounds of iron, corresponding to the present invention. Bacteria regenerate the oxidizing reagent for the other metal sulfide by oxidation of ferrous iron to ferric iron via thiosulfate or polysulfide, which depends on the sulfides of the metals. In the context of the present invention other metal sulfide is preferably molybdenite, for which leaching occurs through an indirect mechanism via thiosulfate. Therefore, the presence of iron compounds in the solution caused by the need for oxidizing iron systems for indirect leaching. In addition, the authors present invention installed an unexpected advantage of the use of trivalent iron to help protect oxidizing iron bacteria when used in accordance with the present invention.
Oxidizing iron microorganisms are extremophiles, which are able to withstand the low pH values. For oxidation of inorganic sulfides there are a variety of acidophilus, oxidizing iron microorganisms. Leaching solution is preferable to inoculate mixed the cult of the swarm, however, some of the main performance characteristics, ultimately, limit the same growth and lead to a predominance of one or more specific strains.
Stage (b) method of leaching is carried out in the reaction volume, which may be a public object in the environment, such as dump, landfill or mine, or in artificial reactor, such as encasing the reactor with stirring tank or column. The sulfide containing molybdenum, it is possible leaching apparatus, which is open and communicates with the atmosphere or is mostly closed. Conventional leaching technology known in the art and not described in the present invention. The following definitions relate to the parameters of the method of biological leaching of molybdenite. "Leaching" or "biological leaching" is used in the present invention interchangeably and means the use of different types of microorganisms for the dissolution of precious metals contained in the inorganic sulfides, direct and/or indirect mechanisms. In the context of the present invention precious metal is molybdenum. The sulfide of molybdenum leached by the reaction with ferric iron, which are formed molybdate and ferrous iron. Microorganisms contribute to the t re-oxidation of ferrous iron in the processing chain. However, it is possible that the mixed culture contains microorganisms that are able to directly oxidize molybdenite.
The molar ratio of dissolved ferric iron to dissolved molybdenum is a parameter used to regulate the way. The regulation process includes continuous, periodic or aperiodic change the specified molar ratio, in which due to microbial oxidation of iron is created or supported molar excess of dissolved ferric iron. A large excess of ferric eliminates any toxic effect of molybdate. Both components must be contained in solution in the form of chemical particles that molybdenum was available for retrieval at the next stage (s) and to trivalent iron acted as complexing reagent. The molar ratio can be changed by changing the concentration of dissolved ferric iron and/or dissolved molybdenum. In the method corresponding to the present invention, it is preferable to set a high concentration of trivalent iron. This can be done by creating a high initial concentration of trivalent iron in the material or solution, respectively, and/or by using any other the Gogo iron, from which later formed trivalent iron. The required concentration of iron can be determined, in particular, according to previously used empirical techniques or by pre-established criteria, such as knowledge of the content of molybdenite and output leaching. This can also be called aperiodic regulation. Although the addition of iron can be carried out in accordance with the expected flow rate, preferably at the time of the experiment, to the corresponding direct measurement of the concentrations of molybdenum and trivalent iron to determine the real values of the critical molar ratio. Specialist in the art is familiar with suitable methods of analysis that are used continuously or intermittently. The ratio calculated by dividing the molar concentration of ferric iron on the molar concentration of molybdenum. It is preferable to perform a method for maintaining a threshold relationship. For tracking molar ratio and, therefore, regulate the flow of iron and/or molybdenum sulfide in suspension at the required values, you can use different methods. The preferred approach to regulation is the use of one or more analytical techniques known to experts in the field of technical and, as probes for direct measurement of the concentrations and molar ratio in the leaching of sediments in the reactor with stirring. The probes can be used for the indirect determination of microbiological activity on the basis of the redox potential of the solution. The probes may issue one or more control signals, which are automatically used to control the corresponding valve or valves so that the supply of iron in the form of sulfide, ferrous iron, sulfate, ferrous iron, or related compounds, or molybdenum in the form of a material containing molybdenum sulfide, in the flow of raw materials was carried out automatically in accordance with the results of real-time determine the value of relationships in suspension. The present invention is not limited to the specific methodology used to measure and refers to modified versions of the above approaches and to any equivalent method.
Preferred neighborhooda concentration of dissolved molybdenum for leaching microorganisms is up to 4.4 g/L. it is Important that the concentration of dissolved molybdenum does not exceed the maximum portable thresholds. In the case of approaching the threshold concentration of molybdenum should be reduced, for example, the way the replacement of the leach solution, dilution of suspended solids, removal of molybdenum and/or decrease speed add-containing molybdenum sulfide.
At the final stage (C) the molybdenum is removed from solution by using appropriate technology, for example, solvent extraction, followed by electrochemical extraction, deposition, or by entering into a suspension of resin-in-pulp with subsequent electrochemical extraction.
In one embodiment of the present invention, the source material preferably is a containing molybdenum sulfide mineral and principal ore of molybdenum is molybdenite (MoS2). Molybdenite extracted from primary ore mineral or extracted as a by-product of copper ore processing in metallurgy or in the form of spent metal-containing catalysts are possible sources of molybdenum for the method corresponding to the present invention. Equally suitable are high-grade molybdenite concentrates, low-grade concentrates, including containing sulfides of other metals, tailings and other wastes that may be generated during mechanical processing, such as the stage of grinding and flotation. Concentrates and tails can also be pre-processed, for example by drying, grinding, dispersion and/or biological videla the air traffic management.
First solution contains at least one type of iron, and may contain other compounds of iron, containing iron in the same or a different oxidation state. In another embodiment of the present invention, the iron compounds are compounds of divalent iron and trivalent iron. Preferably, the divalent iron is introduced in the form of a sulfide containing divalent iron, and/or a ferrous ions, which was previously a part of the soluble ferrous iron compounds. Similarly, preferably, if ferric iron is a ferric ions, which was previously a part of the soluble compounds of trivalent iron or containing iron sulphides of metals. Compounds and divalent and trivalent iron are iron compounds disclosed in this invention, which dissociate in aqueous solutions, preferably completely. Such strong electrolytes are, for example, the sulfates. It is preferable to use compounds of iron in the form of sulphate ferrous iron or ferric sulfate.
The minimum concentration of iron, in the present invention denotes the divalent iron and trivalent iron, made for the I various tasks of method, relevant to the present invention, is fixed. The minimum concentration specified at the beginning and should be maintained during the implementation of the method. The formation of complexes of iron-molybdate can reduce the content of available iron and will need to be added to the leaching solution is more soluble iron or mineral containing iron. Because of the possibility of conversion of ferrous iron to ferric iron and Vice versa, it is enough to establish full concentration, which shall be not less than 0.5 g/l of these iron compounds. Content, comprising 0.5 g/l of iron (of 8.95 mm iron) can be provided, for example, using 1,79 g/l of ferric sulfate. Total iron concentration can be increased up to the limit of solubility, which is determined by the chemical composition of suspended matter. Suspension includes containing molybdenum sulfide material and the leaching solution, which interact in a suitable reaction volume.
In another preferred embodiment of the present invention trivalent iron used at a concentration equal to from 0.5 to 40 g/l, preferably from 2.5 to 21.5 g/l or more preferably from 5 to 20 g/l of trivalent iron. This range of concentrations of ferric optimal for biological above is Oceania molybdenum assuming, the redox potential of the solution is high. However, the threshold concentration is likely to change with the speed of consumption of iron or concentration of molybdenum in the solution. This will influence the content of molybdenite and other sulfide minerals.
The concentration containing ferrous iron sulfide minerals should be determined by methods known to experts in the art, if the leaching solution not add connection iron. A suitable method is, for example, DRA/romance-Germanic Philology (x-ray diffraction analysis/x-ray luminescence). At low concentrations of pyrite, which is introduced containing molybdenum sulfide mineral, it is necessary to add iron to stage (b) leaching.
It is clear that what the microorganisms used for biological leaching of molybdenum depends on the operating temperature. The microorganisms are preferably mixed culture containing mesophilous, moderate thermophile and/or extreme thermophile that come from acidic water obtained from the following sources, but are not limited to, operations, production of sulfides of metals by biological leaching dumps, acid drainage from sulphidic waste rock or natural runoff, acid rock, or produces the t of collections of cultures. The culture of the microorganisms grow and support methods known to experts in the art, such as the processing of acidified solution of mineral salts in tanks with stirring and aeration.
In a preferred embodiment of the present invention the method includes preliminary cultivation of microorganisms in a medium containing inorganic salts and divalent iron to stage (a), i.e., the cell growth and the beginning of the active oxidation of iron, certain specialists in the field of technology happen to interaction and subsequent growth in the presence containing molybdenum sulfide material. The culture medium may be a leach solution. This procedure is particularly useful for adapting cells, stimulation of exponential growth and ensure the concentration of trivalent iron, which is optimal for biological leaching of molybdenite and simultaneous formation of the complexes of molybdate.
In the present invention are suitable mesophilic bacteria selected from among the following, but not limited to, childbirth, Leptospirillum, Ferroplasma, from acidithiobacillus and Ferrimicrobium. It is preferable to use the mesophilous species of the genus Leptospirillum, more preferably strains of Leptospirillum ferrooxidans or L. ferriphilum. Moderately thermophilic bacteria to note the drop in the present invention are selected from the genera from acidithiobacillus, Acidimicrobium, Sulfobacillus and Alicyclobacillus. Extremely thermophilic bacteria selected from the genera Sulfolobus, Metallosphaera and Acidianus.
Biological leaching can be conducted at temperatures up to 100°C. you Can use any suitable microorganism capable of oxidizing iron in this temperature range. Optimum working temperature depends on the kind and type of microorganism and Vice versa. Mesophilic microorganisms grow best in the temperature range from 20 to 42°C, moderately thermophilic microorganisms preferably from 42 to 60°C and extremely thermophilic microorganisms are grown at temperatures up to 60°C. However, all the microorganisms can adapt to temperatures slightly less optimal, although it may lead to reduced rates of growth and rates of leaching.
The method corresponding to the present invention, preferably carried out at a temperature in the range from 20 to 65 °C. the Rate of biological leaching of molybdenite increases with increasing temperature up to a threshold, because extreme thermophile not increase the rate of biological leaching of molybdenite higher values, which is achieved at lower temperatures. In a preferred embodiment of the present invention the phase of the biological leaching molybdeniferous in the mesophilic temperature range from 20 to 42°C. The method of biological oxidation containing molybdenum sulfide materials should be carried out at a temperature corresponding to the upper boundary of the mesophilic temperature range, preferably at a temperature from 30 to 42°C, more preferably at 40°C. For implementing the method at temperatures below 42°With populations of microorganisms chosen from the ranks of mesophilous species, preferably of the above genera. In another preferred embodiment of the present invention the phase of the biological leaching of molybdenite is carried out in a moderately thermophilic temperature range from 42 to 60°C. If the biological stage leaching is carried out at a temperature of from 42 to 60°C, using moderately thermophilic microorganisms, selected from among the above genera. In another preferred embodiment, any pre-processing, which includes biological leaching of sulfides of metals, non-sulfide of molybdenum, particularly chalcopyrite, but represents part of a mixture of sulfides, including molybdenum sulfide, is carried out at a high temperature, preferably at a high temperature in the range from 42 to 65°C, more preferably at 65°C, and the corresponding population of microorganisms selected from the above genera.
When the wasp is the implementation of the method, relevant to the present invention, the temperature of the suspension in the apparatus for biological leaching, such as a tank or the reactor can be adjusted in any suitable way known in the art, such as the choice of the reactor type, size, heating system, insulation and cooling. In one example, the reactor for biological leaching isolate, and heating is performed using energy released during the oxidation of sulfides. The temperature of the suspension regulate using any suitable cooling system, for example, the internal cooling system, typically used by experts in this field of technology.
In yet another preferred embodiment of the present invention at the stage (b) the molar ratio of the amount of trivalent iron to the amount of molybdenum is set to at least 6:1, preferably at least 7:1, more preferably at least 8,4:1, most preferably at least 20:1. It was unexpectedly found that while the dissolved ferric iron is found at concentrations exceeding some threshold value, the absolute concentration is not critical for biological leaching containing molybdenum sulfides. The threshold value is determined by the molar ratio of the number rastvorennogo the iron to molybdenum. Studies have shown that to prevent the toxic effects of molybdate on microorganisms and biological leaching of molybdenite when using columns you need a higher value of the ratio of the number of trivalent iron to molybdenum than using a tank with stirring. This difference is probably due to the fact that the columns of the ratio of solids to solution much more than in tanks with stirring. The column may be more appropriate for the way in which molybdenite biologically leached in the dump.
Stage (b) of the method preferably is carried out at a pH of 2.0 or less. Preferably, if the pH value is in the range from 1.2 to 2.0, more preferably from 1.4 to 1.6. As described above in the present invention, chemolithotrophic microorganisms are acidophilic, so they are characterized by low pH value. For example, in the prior art for A. ferrooxidans indicated that the optimum pH value equal to about 2.5. The authors of the present invention unexpectedly discovered that the further decrease of pH is particularly useful for supporting large concentrations of dissolved ferric iron and molybdenum in accordance with the present invention. In addition, the low pH value of R is the target maintains the high redox potential, equal to not less than 700 mV (relative to the standard hydrogen electrode).
In another preferred embodiment of the present invention a method of leaching is carried out at a redox potential that is equal to at least 750 mV, more preferably at least 800 mV, most preferably at least 900 mV. The high redox potential of the solution is necessary for oxidation of molybdenite and the higher the potential relative to the residual potential of the sulfide of molybdenum, the better the oxidation proceeds from the point of view of speed and output. The ratio of the number of trivalent iron to the amount of ferrous iron has the greatest influence on the constancy of the potential solution for biological leaching. This relationship and the potential of the solution are related by the ratio of Nernst. In the present invention are microorganisms that are able to provide the necessary value of the redox potential by oxidation of iron. Some microorganisms are better than others, oxidize ferrous iron to ferric iron at high redox potential of the solution.
It should be understood that the optimum growth conditions leaching microorganisms also provide maintenance of the redox potential. These conditions include the receipt of a sufficient number of nutrients, aeration, n is the existence of dissolved ferric iron and low pH value. You can also use pure compounds, such as compounds of iron, for impacts in the context of the present invention and/or sulfuric acid to maintain the pH. Specialists in the art there are known various automatic and carried out manually methodologies feed flows of nutrients or selected connections.
In addition to maximise the ability of microorganisms to oxidize the iron, there are also other means of providing for such a high redox potential: the regulation of pH and minimize the rate of expenditure of ferric sulfides of the metals, not the sulfide of molybdenum. For example, the precipitation of ferric significantly reduced when pH of solution, less than 2.0. To minimize the deposition of ferric brings to the maximum value of the ratio of the content of trivalent iron to the content of ferrous iron in solution and thereby brings to the maximum redox potential of the solution.
In addition, minerals are sulphides of metals with less residual potential than molybdenite can be removed using a suitable biological or chemical pre-treatment to eliminate competition for which the oxidant divalent iron. Therefore, the material provided is of molybdenum sulfide, agglomerated material containing one or more sulfides of metals, non-sulfide of molybdenum, pre-processed in order to minimize the content of the metal sulfide, which is not a sulfide of molybdenum, up to the beginning of the active phase leaching of sulphide of molybdenum.
The preferred starting material containing molybdenite, has a particle size less than 50 microns, more preferably less than 15 microns. Particle size affects the flow of leaching due to changes in permeability, sintering, joining microorganisms, specific surface area and the like, it is Preferable to use a mineral with a specific surface area equal to not less than 3 m2/g, more preferably not less than 10 m2/, There is a clear correlation between particle size and rate of biological oxidation of molybdenite. Initial velocity of the biological leaching of molybdenite corresponding to the first 20% of the extracted molybdate, increase with decreasing particle size. Similarly the maximum degree of extraction of molybdate depends on the particle size. Particles having a specific average size, get a mechanical processing such as grinding.
Molar ratio and/or the pH is preferably periodically monitor Analiticheskaya or with ongoing real-time continuous data collection. Methods of analysis, including the determination of concentrations, redox potential and pH, are standard procedures, well known to the experts in this field of technology. The molar ratio monitor by direct or indirect methods. The molar ratio monitor indirect method by determination of the concentration of dissolved ferric iron and dissolved molybdenum and establish a correlation between them. The concentration is preferably determined using atomic spectroscopy with ICP (inductively coupled plasma).
There are several possible options for the supply of iron. Possible embodiments of the present invention may include, but are not limited to, the supply of iron in the form of a soluble sulfate ferrous iron and ferric components oxidize sulfide metal or scrap iron. It is preferable to use a soluble divalent iron and trivalent iron, commercially available. In a preferred embodiment of the present invention a composition of iron is in the form of sulfate ferrous iron in the leaching solution, as it provides an easily accessible source of energy for populations of bacteria that oxidize iron. However, it may come in the form of sulfide mineral containing dohaland the OE hardware. It is shown that the dissolution of a large number of iron-containing sulfides contribute to the microorganisms. It should be understood that the population of the microorganisms used in the present invention, or, at least, part of them are able to oxidize iron and/or sulfide that is necessary for the transformation of these sulfides containing iron. Although any containing ferrous iron sulfide is actually appropriate in the context of the present invention, the pyrite is especially preferred. Containing ferrous iron sulfides are added to the leach solution in the form of mineral or they are such as chalcopyrite, which by nature can be associated with the molybdenite. The number and/or size of the particles added containing ferrous iron sulphides can be chosen so as not to reduce the redox potential of the solution below is required for biological leaching of molybdenite.
As already indicated above in the present description, for the leach solution or suspension of the required minimum redox potential of 700 mV. The potential decrease to the value that is lesser than the above threshold, is a clear indication that increasing the concentration of molybdate reached values that inhibits the activity of microorganisms that oxidize the iron, or that things is there some other factor, leading to inhibition of microbial iron oxidation or consumption of trivalent iron. Therefore, you need to do some surgery to increase the redox potential and the ratio of ferric to the amount of molybdenum. In the simplest case of trivalent iron is added to the leach solution to provide explicit molar excess relative to molybdenum. Of course, you can add other iron compounds, which undergo metabolism leaching bacteria with the formation of trivalent iron. The iron compounds may be added as one containing iron nutrient flow or as part of a complete leach solution. It is also possible to reduce the current concentration of molybdenum by replacing the leach solution, dilute suspensions, removal of molybdenum and/or reducing the rate of feed containing molybdenum sulfide. A system for measuring the redox potential is preferably connected to the automatic control system. The threshold value of the redox potential can be set at the highest value that is greater than 700 mV, and thus to exclude any temporary reduction in metabolic activity and rate of biological leaching or damaged cells.
Remove molybdenum is possible to carry out the method of vannoy for extraction stages (C). The solution for biological leaching can be used for phase separation to obtain a solid substance and a solution and to extract molybdenum from the solution in any convenient manner. For example, molybdenum is extracted by use of deposition, ion exchange, solvent extraction and/or electrochemical extraction. It is preferable to use the technique of ion exchange by using a weakly basic anion-exchanger.
The method corresponding to the present invention can be applied to sequential biological leaching. In particular, molybdenite and associated sulfide minerals leaching consistently. While existing iron sulfide minerals additives are favorable for leaching of molybdenite, sulfides containing other heavy metals, can have a disturbing effect. The latter phenomenon is found often, because such sulfides are easily affected by leaching the ore microorganisms, for example, characterized by low residual or mixed (corrosion) potential. For example, a higher content of copper sulfides can lead to a decrease of the redox potential of the solution due to consumption of trivalent iron with a speed exceeding the speed of microbiological regeneration. In another embodiment, osushestvleniya, the corresponding present invention, includes a step carried out prior to stage (a) removal of sulfide material containing heavy metal with residual capacity equal to less than 700 mV. Sulfide selected from the group comprising bismutite, enargite, chalcopyrite, bornite, covellite, chalcocite, tetrahedrite, pentlandite, millerite, Galena, town and sphalerite, preferably chalcopyrite and bornite, more preferably chalcopyrite.
The sulfide is preferably removed by carrying out the process of pre-leaching material and removal of heavy metal from the residue after leaching, obtained during the operation of the preliminary leaching. In the case of chalcopyrite preliminary leaching can be carried out when a temperature of from 50 to 85°C., preferably from 60 to 80°C., more preferably at 65°C. Heavy metal, such as copper, it is possible by conventional methods to extract from the residue after leaching, obtained during the operation of the preliminary leaching. For pre-leaching in the range of elevated temperatures using oxidizing iron and sulfur moderate or extreme thermophilic microorganisms, preferably extreme thermophilic microorganisms. You can get them from the mixed culture used for leaching of molybdenum. Above this OPI is offering information about the mixed culture, its origin and composition are considered to be correct and without restrictions applicable to the mixed culture, designed for pre-leaching, if it makes sense. Appropriate extreme thermophile may include, but are not limited to, members selected from the genera Sulfolobus, Metallosphaera and Acidianus. One of them is particularly preferred, but not limited to, strains of Sulfolobus metallicus, Acidianus brierleyi and Metallosphaera sedula.
The method corresponding to the present invention is particularly suitable for containing molybdenum sulfide materials which are resistant to leaching. Therefore, the present invention enables industrial leaching of molybdenite, which, as far as known to applicants, has not previously been possible. Oxidation containing molybdenum sulphide is highly specific. When leaching in the presence of trivalent iron are provided with a high reaction rate and outputs. Microorganisms, leaching the ore with ferric protected from the toxic effects of molybdenum. Not required other products of metabolism of microorganisms, in particular, organic composition.
The flow of leaching is adjusted simply by using a molar ratio of dissolved ferric iron to the number of process is i.i.d. molybdenum, which is supported so that was observed sufficient molar excess of trivalent iron. The relative efficiency of the oxidation of sulfide increases - increases the speed and three times increases the output. The rate of leaching of molybdenum equal to 10% per day in tanks with shaking and 0.9% per day in the columns of a, respectively. The provision of such rates of leaching is an important pre-condition for the implementation of effective method of extraction of molybdenum. In addition, compared with the prior art are formed and held in solution significantly greater amounts of dissolved molybdenum. The concentration of dissolved molybdenum, up to 4.4 g/l, provide a simple and economical extraction of molybdenum in subsequent process operations.
The method corresponding to the present invention can easily be implemented technically and conduct cost-effective manner. It is shown that the molybdenite solubilizated leaching of the blade and it is feasible. Detected a significant increase in output per unit area and per unit time. In the method as a starting material can be used effectively concentrates and waste streams processing molybdenum and copper ore.
The following examples are presented that is are for illustration, and not for limitation. The examples use of standard reagents and buffers not containing active impurities (if practicable).
BRIEF DESCRIPTION of DRAWINGS
Figure 1 shows the minimum inhibitory concentration containing Defense compounds against oxidizing iron bacteria.
Figure 2 presents the time dependence of biological oxidation of Fe(II) in the presence of Mo.
Figure 3 presents the values of Eh of the solution containing MoS2flasks containing different amounts of added ferric.
Figure 4 presents the biological leaching MoS2when different amounts of added ferric.
Figure 5 presents the relationship between particle size and rate of biological leaching MoS2.
Figure 6 presents the dissolution of Mo and Cu in a column with a long adaptation under mesophilic conditions.
Figure 7 presents the effect of the Fe concentration in the leaching solution to dissolve Mo.
On Fig shows the change in the redox potential of the leach solution while changing the concentration of Fe in the leachate solution.
Figure 9 presents the dissolution of Mo and Cu in a column with a long adaptation under mesophilic conditions.
Figure 10 shows the change of concentration the walkie-talkies of iron in the leaching solution.
Figure 11 presents the changes in the concentrations of Mo in the leach solution in accordance with changes in the concentrations of iron in solution.
On Fig shows the change in the redox potential of the solution to change the concentrations of iron in solution.
On Fig presents the Fe concentration in the leaching solution, which is included in the column and out of the column.
On Fig presents the values of pH in the leaching solution emerging from the column of the layer thickness of 1.5 m
On Fig presents the values of the redox potential in the stream exiting the column of the layer thickness of 1.5 m
On Fig presents the normalized daily rate of solubilization of the Mo layer thickness of 1.5 m
On Fig a comparison of dissolved Mo in small and large laboratory columns.
On Fig presents the impact of high Fe content and high content of Mg in the extraction of Mo from re-ground three-component composition at 25°C and 0.6% of solids.
On Fig presents the concentration of dissolved iron in the study to determine the effect of the solution of iron in biological leaching of Mo.
On Fig presents the concentration of dissolved molybdenum in the study to determine the effect of the solution of iron in biological veselaj is of Mo.
On Fig shows how increasing concentrations of iron in solution leads to an increase in plateau adaptation leaching microorganisms to the effects of Mo.
This study was conducted to determine whether the toxic effects Mo for oxidizing iron microorganisms on the type of chemical compounds containing Mo.
Active culture oxidizing iron microorganisms were inoculable (5 ml) in 45 ml of fresh medium 2 ΜM (ΜM = modified atmosphere Kelly) in each of 10 Erlenmeyer flasks of 250 ml OF 2 ΜM medium containing 0.8 g/l of ammonium sulfate, 0.8 g/l of sulfate heptahydrate and magnesium 0.08 g/l of potassium dihydrophosphate. Medium containing 6 g/l of ferrous iron (as sulfate heptahydrate ferrous iron as an energy source and the value of its pH was brought to 1.5 with sulfuric acid. The inoculum was 5-day mixed culture of mesophilic oxidizing iron microorganisms grown in medium 2 ΜM, containing 0.6 g/l of ferrous iron (as sulfate heptahydrate ferrous iron). Preparation insulinoma culture began to shake flask culture mixed oxidizing iron mesophilous species that are biologically videlacele molybdenite in the environment 2 ΜM with the addition of iron.
These 10 cultures were incubated at 24°C With shaking at 10 rpm during the night, to give cells the ability to grow and oxidize the iron in the absence of Mo. The next day, according to titration with permanganate solution is about 10% contained in iron flasks were subjected to biological oxidation. Different amounts and forms of Mo was added to actively growing cultures. The contents of one flask was not treated and used as a control. Mo was added with concentrated source solutions in the form of sodium molybdate (original solution containing 48,9 g Mo/l in the form of Moo3dissolved in 1M NaOH, then neutralized with sulfuric acid), silicomolybdate (H4SiO4·Moo3·xH2O) or phosphomolybdate (Moo3·H3PO4·xH2O). The starting solutions of sodium molybdate and phosphomolybdate were completely transparent. The original solution silicomolybdate contained a small amount of flocculent precipitate. Nominally Mo was added to the flasks at concentrations of 10, 100 and 1000 mg/L. the Actual concentration of dissolved Mo were determined using spectroscopy with inductively coupled plasma (hereinafter referred to COI) after centrifugation of the samples for 5 min at 1200 × g.
The pH value was maintained equal to <2,0 if necessary, by adding sulfuric acid. The Eh values of the solutions were determined using a combination electrode platinum/silver-chloride took silver at the and. Readings were corrected for the standard hydrogen electrode (BOO) by adding 199 mV. The Eh values of the solutions in flasks was monitored in time, until almost all of the iron is not subjected to biological oxidation in the control flask, which occurred after 3 days. At this point, all flasks concentration of Fe(II) was determined by titration with permanganate. Comparing expressed in % of the amount of iron which has been subjected to biological oxidation in the presence of compounds of Mo at different concentrations (Figure 1).
The results show no inhibition of microbial oxidation of Fe at equal from 8 to 11 mg/l concentration of Mo added in the form of Na-Mo or R-Mo. However, more than 50% inhibition of oxidation of Fe occurred at the lowest concentration of Si-Mo (7,3 mg/l). At a concentration equal to from 56 to 101 mg/l, all connections Mo had a strong inhibitory effect (Figure 1). After another 4 days of incubation, the results did not change. Complex compounds Mo (R-Mo, Si-Mo) had the same inhibitory effect as molybdate Na.
This study showed that the addition of ferric ions to a cultural environments provides biological oxidation of iron at elevated concentrations of Mo.
One group of 4 flasks (flask "L") contained culture medium 2 ΜM with the addition of 2 g/l Fe(II) (in the ideal of sulfate heptahydrate ferrous iron). The second group of flasks (flask "H") contain the same basic environment, but at higher concentration (6 g/l) Fe(II). These 8 flasks were inoculable with 5 ml of oxidizing iron microbial culture containing 11 mg/l Mo (as sodium molybdate), taken from the study described in Example 1. After 3 days of incubation at 24°C according to change the value of the Eh of the solution more than 99% of the ferrous iron was subjected to biological oxidation in all 8 tubes. Then the flask using 48,9 g Mo/l initial solution (described in example 1) in varying amounts was added to the molybdate Na. After 5 min to ensure the flow of potential complexing Mo with trivalent iron in all flasks was added an additional amount of ferrous iron. The initial concentration of ferrous iron was determined by titration with permanganate. Dissolved Fe and Mo were determined by spectroscopy using EQ. The ferric iron was determined by subtracting the ferrous iron content of the total iron content (table 1).
The contents of the flasks used to study the effect of ferric iron on the toxic effects of the Mo
|The flask||Starting the Fe(II) g/l||Initial Fe(III) g/l||Initial full Fe g/l||The initial Mo mg/l||The result (6 days of incubation)|
|L-C||4,4||3,2||7,6||0||All Fe was subjected to biological oxidation|
|L-1||4,2||3,3||7,5||14||All Fe was subjected to biological oxidation|
|L-2||4,0||3,3||7,3||124||All Fe was subjected to biological oxidation|
|L-3||4,0||3,0||7,0||1106||Fe has not been subjected to biological oxidation|
|H-C||5,0||5,9||10,9||0||All Fe has undergone biological ocil the tion|
|H-l||5,5||6,0||11,5||13||All Fe was subjected to biological oxidation|
|N-2||of 5.4||6,5||11,9||117||All Fe was subjected to biological oxidation|
|H-3||of 5.4||6,2||the 11.6||1090||All Fe was subjected to biological oxidation|
Flasks were incubated at 24°C with shaking at 180 rpm/min Through 50 h added divalent iron is fully (>99%) were subjected to biological oxidation in all flasks "H" (containing iron in the highest concentrations). Iron is also fully oxidized in flasks "L" except for the bulb L-3, in which the oxidation passed by only 15%. After 6 days of incubation in this flask iron is no longer subjected to biological oxidation.
The results showed that complete biological oxidation of added ferrous iron was relatively high (of the order g/l) concentrations of Mo. Superior move is here Mo oxidizing iron by microorganisms correlates with the addition of culture medium trivalent iron at higher concentrations.
This study showed that trivalent iron obtained abiotically by oxidation of ferrous iron peroxide, has characteristics similar to the characteristics of trivalent iron, obtained by biological oxidation, i.e. provides the biological oxidation of iron at relatively high concentrations of Mo. This indicates that trivalent iron, and not some other metabolite, provides biological oxidation of iron at elevated concentrations of Mo.
Trivalent iron was obtained abiotically carried out by dropwise and with stirring, add 1.3 ml of 30% H2About2to 100 ml of 0.2 n solution of H2SO4containing 12 g/l Fe(II) sulfate heptahydrate ferrous iron. The final pH value was equal to 1.47 and Eh was $ 878 mV, indicating that the almost complete oxidation of all iron.
Trivalent iron was obtained biologically from the culture medium 2 ΜM, containing 25 g/l Fe(II) (in the form of sulfate heptahydrate ferrous iron). Wednesday was inoculable a mixed culture of mesophilic oxidizing iron microorganisms. After incubation for one week with shaking at 24°C the number of cells was increased to 4×108/ml and, as was shown equal to 890 mV value Eh of the solution, oxidized almost the CE iron. The pH value was $ 1,52. To remove microorganisms, the solution was filtered through a membrane filter with holes the size of 0.45 μm and then through a membrane filter with holes the size of 0.22 μm. After filtering according to the determination by spectroscopy using EQ solution contained 22.1 g/l of dissolved Fe.
The solution is subjected to biological oxidation of iron (12 ml) or a solution oxidized by the peroxide of iron (25 ml) is brought up to a volume equal to 45 ml with culture medium 2 ΜM. Added sulfate ferrous iron to a concentration of 6 g/l Fe(II). Added Mo using concentrated source solution of sodium molybdate (table 2). Control flasks containing 45 ml of culture medium with the addition of only sulfate ferrous iron. The flask was inoculable with 5 ml of 6-day culture mixed oxidizing mesophilic iron microorganisms grown in 2 ΜM with the addition of 6 g/l Fe. This flask had previously inoculable a mixture of oxidizing mesophilic iron cultures previously grown in flasks containing sulfate ferrous iron and sodium molybdate and columns, in which the biological leaching of molybdenite. Initial concentrations of dissolved iron and molybdenum were determined by spectroscopy using EQ. Incubation was carried out for 15 days at 24°C PR is shaking at 180 rpm/min Periodically determine the values of the pH and Eh of the solution.
Complete biological oxidation of Fe occurred for 6 days in the presence of from 920 up to 941 mg/l Mo using subjected to biological oxidation of iron or oxidized by the peroxide of iron, as evidenced by the value of the Eh of the solution, which increased to in excess of 900 mV from the initial value from 672 to 677 mV (621 mV without adding ferric). In contrast, the value of Eh in the flask, not containing added ferric (with the exception of a small number introduced to inoculate) and containing 960 mg/l Mo, 15 days remained almost unchanged and equal 639 MB.
These results indicate that trivalent iron protects oxidizing iron microorganisms from inhibition by Mo. In addition, trivalent iron has a protecting effect when it is received and through biological oxidation by peroxide oxidation. Thus, to protect cells from inhibition by the MoE does not require other metabolites of microorganisms, such as amino acids.
Also found that the reagent ferric sulfate (PCT) protects oxidizing iron microorganisms from inhibition by Mo, but this depends on the supplier of the chemical. The group is ARS Erlenmeyer was placed in 45 ml of medium ΜM, containing 6 g/l of ferrous iron (as sulfate ferrous iron) with or without added 1.0 g/l Mo (Na molybdate) and with or without adding reagent ferric sulfate, obtained from two commercial suppliers (table 3). The flask was inoculable using 5 ml of an active culture of oxidizing iron microorganisms grown in medium 2 ΜM, containing 16 g/l Fe.
5 days have been subjected to biological oxidation of iron (Eh >900 mV) in flasks containing PCT provider 2, as well as in the control flask without adding Mo. Even after 26 days, only a small amount of Fe was subjected to biological oxidation (increase Eh less than 15 mV) in flasks containing PCT provider-1, or in the control flask without adding Mo. Thus, the PCT provider-1 had an inhibitory effect on the oxidizing iron microorganisms. PCT retained the ability to inhibition even after pre-treatment by aeration within two weeks or processing peroxide. These results indicate that some forms of commercially available reagent ferric sulfate contain a substance inhibiting the growth of oxidizing iron microorganisms.
This study showed that increasing the concentration trehu entogo iron in the environment provides a flow of biological oxidation of Fe(II) at elevated concentrations of Mo.
500 ml of culture containing environment 2 ΜM and 12 g/l Fe(II) (in the form of sulfate heptahydrate ferrous iron), at pH of 1.5 was inoculable a mixture of active oxidizing iron microorganisms grown in medium 2 ΜM with the addition of Fe (2 ml), and frozen suspension cells derived from laboratory column studies biological leaching.
The culture was placed in a shaking device at 30°C. was Monitored by pH and Eh, the pH value was set equal to 1.6, if necessary with the aid of sulfuric acid. After 9 days all the iron was subjected to biological oxidation, as evidenced by the Eh value equal to 943 MB.
Aliquots of 50 ml subjected to biological oxidation of a solution containing oxidizing iron microorganisms were placed in a 4 bulb for shaking and each was placed 6 g/l Fe(II) sulfate heptahydrate ferrous iron and 0, 1, 2 or 3 g Mo/l using the original solution Mo concentrations of 50 g/l (as sodium molybdate). The pH value was set equal to 1.5 with sulfuric acid. According to Eh measurements and titration with permanganate after two days incubation at 25°C and shaking at 200 rpm all the iron was oxidized. This shows that biological oxidation of Fe will not be affected even 3 g/l of dissolved Mo.
To establish whether cells grow and oxidize Fe in Pris is accordance Mo at concentrations > 1.0 g/l solution of ferric received by filtration of the residue content of the flask above, in which 12 g/l Fe(II) was completely subjected to biological oxidation. The solution was first filtered through a membrane filter with holes the size of 0.45 μm and then through a membrane filter with holes with a size of 0.2 μm. Aliquots of 45 ml does not contain cells of the filtrate was added 4 bulb with 0, 1, 2 or 3 ml of a solution containing 50 g Mo/l, 1.5 g of sulfate heptahydrate ferrous iron and 5 ml of active cells, which were grown in the above flask containing 0 g/l Mo. Real Fe and Mo were determined by spectroscopy using EQ after centrifugation of the solution at 1200 × g for 5 min Initial concentration of iron ranged from 15,8 to 16.1 g/l and initial pH values ranged from 1.6 to 1.7. After 6 days of incubation iron was completely subjected to biological oxidation in all flasks, as shown by the increase in Eh from the initial value equal to 680, to make up from 685 to more than 900 mV in 4-6 days (Figure 2). Required more than two days to iron completely subjected to biological oxidation at the highest concentrations of Mo, and this indicates that microbial growth was slightly lower at the highest concentrations, Mo.
The analyses carried out after completion of the study the project, showed that during the study the concentration of dissolved Mo and Fe were not decreased.
To confirm that the oxidizing iron microorganisms grow at high concentrations of Mo, culture, grown at 912 mg/l Mo (Figure 2), was inoculable (5 ml) in 45 ml subjected to biological oxidation and filtered (0.2 μm) environment 2 ΜM, containing 12 g/l of trivalent iron (bulb E-1) or 22 g/l of trivalent iron (bulb E-2). Before inoculation was added sulfate ferrous iron (6 g/l Fe) and the initial solution of Mo (3 ml of 50 g/l). Incubation was carried out for 6 days at 24°C with shaking at 180 rpm/min metal Concentrations were determined using spectroscopy using EQ after centrifugation of the samples for 5 min at 1200 × g. The number of cells of microorganisms were determined using the device count bacteria Petroff-Hausser. The pH and Eh were determined daily.
The results show that the culture was grown and oxidized iron in the presence of almost 3 g/l Mo (table 4). Intermediate measurements of Eh and counting the number of cells showed that the rate of growth in these two flasks were close. Microscopic examination after 4 days of incubation showed that many of the cells of the microorganisms was a curved stick or spiral, which is similar to the form of Leptospirillum. Found mobility, which indicates that life is sposobnosti cells.
The growth of oxidizing iron microorganisms in the presence of the Mo
|The flask||Fe, g/l||Mo, mg/l||pH||Eh, mV BOO||Cells/ml|
|E-1 primary||17,2||2810||of 1.57||682||0,9×107|
|E-1 final (6 days)||17,6||2907||1,58||933||of 1.6×108|
|E-2 initial||25,2||2885||1,56||694||of 1.1×107|
|E-2 final (6 days)||to 25.3||2933||1,53||939||1,7×108|
To determine the relationship between the concentration of dissolved iron and most what concentratie, when oxidizing the iron microorganisms capable of biologically leaching molybdenite, the end of culture from example 4 (bulb E-1 or E-2) was added to the flask containing various amounts subjected to biological oxidation of trivalent iron (filtered solution containing 22.1 g/l Fe, from Example 3) or a fresh environment ΜM, with or without added sulfate heptahydrate ferrous iron. All flasks were placed molybdenite high purity (Molyform M5, NS Starck, Goslar, Germany) (table 5).
The contents of the flasks in the study of biological leaching of molybdenite
|The flask||The solution is subjected to biological oxidation of Fe (22.1 g/l Fe)||The culture solution (example 4)||2 MKM||Sulfate ferrous iron||Molybdenite|
|F-1||20 ml||20 ml S-2||0||0||0,805 g|
|F-2||20 ml||20 ml S-1||0||0,805 g|
|F-3||0||20 ml S-1||20||0||0,803 g|
|F-4||0||5 ml S-1||45||1.35 g||1,005 g|
Initial concentrations of dissolved Fe and Mo were determined by spectroscopy using EQ after centrifugation at 1200 × g for 5 min (table 6). Flasks were incubated at 24°C with shaking at 180 rpm/min for 79 days.
|The initial parameters of the solution in the study of biological leaching of molybdenite|
|The flask||pH||Eh, mV||Fe, g/l||Mo, mg/l|
The Eh value was rapidly decreased to approximately 720 mW in flasks F-1, F-2 and F-3 for the first two days after the start of the study, probably due to the reaction of ferric ions with molybdenite (Figure 3). However, Eh dissolved iron even at >90% consisted of compounds of trivalent iron. The value of Eh after 20 days was rapidly decreased in the flask F-2 and 45 days in the flask F-1. In contrast, over 80 days in flasks F-3 and F-4 were not detected signs of biological iron oxidation (increase Eh).
According to eject the Mo is similar to the dependencies for Eh. Concentrations of dissolved Mo began to increase with increasing Eh to values in excess of 750 mV, due to the biological oxidation of iron (Figure 4). These results indicate that biological leaching of molybdenite need a large value of the potential (750 mV) and that for the biological oxidation of ferrous iron at high concentrations of RA is solved Mo high concentration of trivalent iron.
The maximum concentration of dissolved Mo in the solution was approximately 4 g/l (Figure 4). As the concentration of dissolved Mo in the flask F-2 was close to 4 g/l, the value of Eh began to decline. This may indicate a reduced oxidation of iron by microorganisms toxicity Mo or may indicate the deposition of Mo, because the concentration of dissolved Mo also began to decline.
This study was repeated with the addition of 1.0 g of molybdenite in 4 flasks, each of which contained an aliquot of 50 ml culture of active oxidizing iron microorganisms containing 20 g/l Fe at pH 1,68, Eh equal to 770 mV (showed that >95% of the iron was trivalent) and 1.8×108cells/ml Initial concentration of dissolved Mo in two of these flasks was equal from 155 to 167 mg/l In the other two flasks were placed 0.5 ml and 1.5 ml of concentrated (50 g Mo/l) initial solution of sodium molybdate, which led to the initial concentration of Mo in flasks, according to the determination by spectroscopy using EQ equal to 666 and 1595 mg/L.
Flasks were incubated at 24°C and 180 rpm/min for 63 days. And in this case, the initial value of the Eh of the solution was reduced to approximately 710 mV. The Eh value started to increase in all the flasks after 21 days and exceeded 750 mV 32 days and 850 MB over 53 days. The concentration of the emission of dissolved Mo in day increased to 63 3353 and 3581 mg/l in two flasks, which was not initially added sodium molybdate. Concentrations of dissolved Mo was 3919 and 4404 mg/l in the flasks, which were first added to 0.5 ml and 1.5 ml of a solution of sodium molybdate, respectively.
These results confirm that at high concentrations of Fe in the solution of biological oxidation can provide leaching of Mo from molybdenite and lead to high concentrations of Mo in solution.
We have shown that microbial growth and oxidation of iron at high concentrations of Mo in solution is not due to selection of resistant Mo strains of microorganisms. Cells were extracted from the solid molybdenite from a flask containing 3581 mg/l of dissolved Mo and 20 g/l of trivalent iron. The molybdenite was allowed to settle under gravity. Dissolved phase was decanted and discarded. For careful leaching of molybdenite was added an aliquot of fresh medium 2 ΜM, containing neither Mo nor Fe. Solids again allowed to settle. Dissolved phase was re-merged. By this method of suspension was removed a large part of the dissolved Mo and Fe(III). Additionally added 2 ΜM and solids very vigorously shook to remove cells. After keeping for 5 min dissolved phase consisted of 1.7×108cells/ml, mostly curved and spiral, similar to bacteria Leptospirillum. Under the odd number of cells showed almost all microorganisms were strongly associated with molybdenite in the original solution culture, the merged solutions contained <1%.
Aliquots (1.0 ml) of cell suspension obtained after vigorous shaking solids, was added to 2 ΜM, containing 4.5 g/l Fe(II) and Mo at various concentrations (as sodium molybdate) in the range from 4.4 to 922 mg/l Initial number of cells was equal to 3.4×106cells/ml Incubation was carried out at 24°C with shaking at 180 rpm for 11 days.
The microorganisms in suspension cells derived from solid molybdenite, do not grow and do not oxidize the iron when placed in culture medium with sulfate ferrous iron containing 97 mg/l Mo or 922 mg/l Mo - number of cells after 11 days was less than 106/ml and Eh and titration with permanganate indicated no significant oxidation of Fe. On the contrary, good growth and complete biological oxidation of iron was observed when the suspension was inoculable in culture medium containing low concentrations of Mo (4.4 and 14 mg/l Mo) was observed with high mobility of the cells of bacteria of the type Leptospirillum, the number of cells exceeding 108/ml and according to Eh measurements and titration with a solution of permanganate iron was completely subjected to biological oxidation.
These results show that the glue is key, who carried out the biological leaching of molybdenite in solutions with high concentrations of dissolved Mo (3.6 g/l) and high concentrations of trivalent iron, were completely ingibirovany in the presence of 97 mg/l Mo when diluted with fresh culture medium containing little Fe(III). This shows that the selection of resistant Defense microorganism strain is not caused by growth at high concentrations of Mo. Rather high concentrations of ferric iron in solution provide biological oxidation of iron and biological leaching of molybdenite at high concentrations of Mo in solution.
Found that the rate of biological leaching of molybdenite is higher at higher temperatures and smaller particle sizes, which is important to develop a method of biological leaching of molybdenite. Examined two types of samples of molybdenite.
Used in lubricants containing molybdenite products of high purity (Molyform®M5, M15, M30 and M50) with particles of different sizes received from the company ..Starck, Goslar, Germany. Specific surface area (m2/g) was equal to: M5, 9,03; M15, to 5.21; M30, 3,65, and M50, 3,42. The size of the particles (R90) was equal to: M5, 2.9 μm; M15, 12 μm, M30, 27 μm and M50, 36 microns.
Containing molybdenite solids were also received from waste streams pre the acceptance for the preparation of copper concentrates in the Western United States. These materials included a sample from the first cleaning device tailings containing 4% molybdenite, 53% chalcopyrite and <3% pyrite, and the rest were mainly represented by talc and silicon dioxide. United sample, composed of other samples of the waste stream contained 40% chalcopyrite, 7% molybdenite, <3% pyrite, and the rest were mainly represented by talc and silicon dioxide. The sample from the first cleaning unit tails and combined samples were grinded again. Chalcopyrite was removed by biological leaching at 65°C with a mixture of oxidizing iron and sulfur extreme thermoflow, including Sulfolobus metallicus, Acidianus brierleyi and Metallosphaera sedula. The material was added (10% solids) to 2 l of a solution OF 2 MICRONS in the reactor with stirring and aeration. The value of the Eh of the solution in these studies was relatively low (<700 mV) and under these conditions the extraction of Mo did not occur. When the analysis of the solution showed that the extraction of si is close to 100%, the residue containing pyrite and molybdenite, extracted, washed and analyzed. When processing residue from which biological methods extracted copper, Mo almost did not dissolve in hot 3 N. HCl, and it was shown that Mo was not removed and re-deposited.
The culture of the microorganisms used in research on biological leaching, wnac the Les contained a mixture of oxidizing iron and sulfur of acidophilus, retrieved from mine waters. It was cultivated and kept in tanks with agitation and aeration at room temperature (about 24°C) in a mixture of pyrite, sulfur, chalcopyrite and molybdenite added to a solution of inorganic salts 2 MKM, the pH value of which was set equal to 1.4 to 1.6 using sulphuric acid.
A study of the biological leaching of molybdenite was performed by adding molybdenite (0.6 g/l) in a flask containing a solution of 2 MKM with the addition of 6 g/l of ferrous iron in the form of sulfate heptahydrate ferrous iron. The pH value was set equal to 1.4 to 1.6 using sulfuric acid. The flask was inoculable active cultures of bacteria previously grown in the medium with iron and the addition of molybdenite, and were shaken (180 rpm) at different temperatures. Periodically, samples were taken of solutions for determination of pH, redox potential (Pt electrode, Ag/AgCl reference electrode) and dissolved metals using spectroscopy using EQ. All redox potentials are expressed relative to the standard hydrogen electrode (BOO).
There has been a clear correlation between surface area and rate of biological oxidation of molybdenite high purity (Figure 5). The initial velocity of the biological leaching of Mo (the first about 20% of Mo extracted with ongoing PA is allele experiments in two identical flasks) increased with decreasing particle size and varied from 1.77%/day when using the M50 to 4,91%/day when using M5. The average speed of the biological leaching of four molybdenite at 24°C was equal 3,22 mg Mo/m2/day (standard deviation) = 0,25), which corresponded 3,88×10-10mol MoS2/m2/c (WITH a=0,30).
In these studies, the maximum degree of extraction of Mo was also dependent on particle size. From M5 when conducted parallel experiments in two identical flasks after 50 days biological leaching has removed more than 80% Mo, while the M50 when conducted parallel experiments in two identical flasks after 75 days biological leaching took less than 30% Mo.
Re-refining industrial molybdenite concentrate was increased extraction of Mo from 12% (the initial concentrate) to 28% (re-blended) after one month of biological leaching.
The rate of biological leaching of molybdenite was also increased with increasing temperature. Mo biologically videochelsea of molybdenite in mixed waste processing of minerals in the amount equal to 2.5%/day at 25°C, with an increase to 10.2%/day at 40°C (table 7).
For determining the velocity of the biological leaching data for the first 40-60% extracted Mo was approximatively model, shrinking core. Arsenicosa dependence of log K vs. inverse temperature gave a linear relationship (r
|The effect of temperature on the rate of biological leaching of molybdenum from mixed waste mineral processing|
|Temperature, °C||Extraction speed Mo, %/day|
|* Average of two values, the|
A study of the biological leaching of molybdenite high purity (M5) also carried out in the temperature range from 25 to 40°C. These results led to linear arsenicosa dependence and close the apparent activation energy equal to 61.2 kJ/mol.
The way biological oxidation of mo is idenity should be effective in the upper part of the mesophilic temperature range (40°C), because extreme thermophile at 65°C did not increase the rate of biological leaching MoS2.
Found that the regulation of the chemical composition of the leach solution, in particular the concentration of iron is a critical work setting means necessary to reduce the toxic effects of Mo on the populations of mesophilic and oxidizing acidophilic Fe microorganisms. Toxic effects Mo clearly demonstrated in the above example, as observed reduction of the redox potential of the leach solution, because the inhibited cells are not able to oxidize ferrous iron to ferric iron at a rate sufficient to prevent its accumulation in the solution. Requirements for the amount of soluble iron is easy to demonstrate for leaching columns used for modeling biological leaching in the dumps.
Download column. The waste stream from the hub (DSO) was dried and used without further modification in the columns described below and used to study biological leaching of molybdenite. According to the analysis of the DRA/romance-Germanic solid had the following composition (in wt.%): CuFeS2(48%); MoS2(6.6 percent); FeS2(<3%); S-S (23%); talc (18%) and quartz (15%). The particles had sizes in the range of 5-25 microns.
A. Column 5 with long-term adaptation. About 750 g andesite gravel with particle size less than1/4inch was glomeruli with 179 g download chalcopyrite/molybdenite using 1 N. H2SO4as agglomerated funds. The agglomerated material was filled polycarbonate column with a diameter of 0.05 m and received the active layer has a height of 32 see Column operated at room temperature throughout 460 days. Leach solution was injected with a velocity of 0.003 gallons/square foot/min in the upper part of the column using a peristaltic pump. The aeration is conducted through the channel in the lower part of the agglomerated layer with a velocity of 1.2-1.5 l/min
The inoculation. The column was inoculable with 200 ml of active mixed mesophilic culture, previously used for biological leaching of molybdenite. First, the culture was mixed with 800 ml of 9K basic salts solution and received the initial concentration of suspended cells, equal to 1.25×106cells/ml, and then it was pumped through the layer in the column.
The composition of the leach solution. Source environment 9K contained, in g/l (NH4)2SO4(3,0), KCl (0,1), MgSO4·7H2O (0,5), K2HPO4(0.5) and Ca(NO3)2·4H2O (0,1). As described below, was used undiluted and diluted in the ratio 1:10 9K basic salt solution within specified time-frames. The final concentration of iron in solution was regulated at each leaching cycle. If necessary, regulating the pH during the leaching cycle in the tank was additionally added 11 N. H2SO4.
Beginning in 9K leaching solution (pH of 1.75) was added to about 2.5 g/l of ferrous iron. Leachate solution was replaced with fresh 9K + 2,5 Fe 31 days to reduce the concentration of copper in the stream. Partial replacement media (200 ml) was also performed in the days of 389 418, although the replacement solution was a 0,1X 9K with the addition of 20 g/l Fe.
Over time the concentration of iron in the leaching solution was gradually increased with additional ferrous iron added to the tank leach solution in solid form in the form of FeSO4·7H2O day 53 (+5 g/l); at day 143 (+5 g/l); at day 195 (+8 g/l); a day 276 (+5 g/l) and was additionally added in the days 389 418 to maintain equal 20 g/l concentration of Fe contained in the solution after partial replacement of the solution.
Sampling/analysis. Sampling from the reservoir was performed in the usual way by adding deionized water to compensate for evaporative losses and determine the pH, the concentration of Mo,Cu and Fe and the redox potential of the solution. The ORP values are given relative to the standard hydrogen electrode. Metal concentrations were determined using spectroscopy using EQ.
Experimental biological leaching download molybdenite. For 460 days of the boot was removed less than 50% and 20% contained Cu and Mo, respectively (Fig.6). The dissolution of copper was generally preceded by intensive dissolution of Mo. As the flow of biological leaching leaching solution modified by increasing the concentration of ferrous iron in days, 53, 143, 195, 276, as shown in Fig.7, which shows the concentration of Fe and Mo in the circulating washing solution. Days, after which the concentration of iron in solution was increased, as indicated by the arrows. We note a clear plateau for the concentration of Mo. You can see that the offset above this adaptive plateau precedes the regulation of the concentration of iron (as ferrous sulfate). These data were among the first linking resistance to Mo and composition of the leach solution. In the end achieved the maximum concentration of Mo in the solution is equal to 1.86 g/l, which corresponded to the concentration of Fe in solution equal to 24.2 g/l High redox potential at this concentration Mo (901 MB, BOO) shows that the activity of microorganisms oxidizing Fe, not ingebyra the Ana high concentration of soluble Mo.
The study of oxidation-reduction potential (ORP) of the solution after 111 days biological leaching clearly demonstrates the advantage of adding iron to leach system (Fig). In this case, a potential solution in the day 231 exceeded 900 mV (1,23 g/l Mo) after increasing due to microbial iron oxidation occurring after the previous addition of ferrous iron (day 195). The potential reached a maximum value equal to 938 mV, day 248 (1.28 g/l Mo), and then declined to 143 mV to a value of only 795 mV, day 276 (1,49 g/l Mo). This was a clear indication that increasing the concentration of Mo resulted in value, the inhibitory activity of microorganisms oxidizing Fe, in leach solution in which the concentration of Fe was only 16.5 g/L. Therefore, a sufficient amount of Fe was added to the leaching solution in a day 276 to provide values that are greater than 20 g/l Fe, after full circulation and mixing leach solution. The addition of Fe to the leaching solution is marked by an arrow (Fig). A potential solution is first decreased in response to the addition of Fe(II), and then increased in day to 907 304 mV (1,49 g/l Mo), showing that the activity of microorganisms oxidizing Fe, no longer suppressed.
C. Column 72 with long-term adaptation. Prepared another column the diameter 0.05 m, to further demonstrate the impact of the Fe solution to the toxic effects of Mo on populations of oxidizing sulfides of microorganisms in the dumps. Approximately 602 g andesite gravel with particle size less than % inch was glomeruli from 75.3 g download chalcopyrite/molybdenite using 1 N. H2SO4as agglomerated funds. Under the active layer had 250 g andesite rocks as a drainage layer. On the active layer of agglomerated download similarly placed 101 g of andesite as a covering layer in order to facilitate more uniform distribution of the supplied leach solution. Speed aeration and supply of leach solution was the same as described above in this example. Column worked at room temperature for only 194 days.
The inoculation. The column was inoculable using a mixture of 200 ml of frozen mixed mesophilic source culture, previously used for biological leaching of molybdenite, and 800 ml of cell suspension biomass recovered after column described above in this example. In this case, the cells were washed from the remainder of the biological leaching using solution 9K + 7.5 g/l Fe(II). Solids were allowed to settle and the cell suspension was separated by decantation. The concentration of suspendido is the R cells in the vessel was equal to 9.0×10 7cells/ml of This suspension was pumped through the layer in the column, and then replaced with fresh medium as described below.
The composition of the leach solutions. Except as noted cases used the original environment 9K, as described above in this example. And in this case, the concentration of the solution of iron regulated during the leaching cycle. If necessary, regulating the pH during the leaching cycle in the tank was additionally added 11 N. H2SO4. Beginning in 9K leaching solution was added to about 7.5 g/l ferrous iron (pH 1,59). Leach was replaced with fresh solution at this concentration of Fe in 6 days, 68 and 106. However, it was interesting to demonstrate the impact of reducing the concentration of Fe in solution on the toxic effects of Mo. So in the days of 40 and 49, the solution was replaced with fresh 9K with the addition of only 2.5 g/l of ferrous iron. The last solution that replaces the leaching solution at day 141 represented with "low concentration of nutrients," a composition including dilute sulfuric acid with the addition of 0.1 g/l (NH4)2SO4and 7.5 g/l ferrous iron (pH 1,29).
Experimental biological leaching download molybdenite. The progress of the dissolution of Mo and Cu are presented in Fig.9. Between days 17 and 27, the rate of dissolution of Mo was approaching equal to 0.8%·the TCI -1and the speed of dissolution of Mo and Cu were practically the same speed in the period from day 51 to day 159 (0,25%/day and 0.22%/day, respectively). After 194 days from the material loading was leached 68% Cu and 49% Mo.
However, it was interesting to demonstrate the impact of the decrease in the concentration of Fe in solution on the toxic effects of soluble Mo. Experimental methods included the use of this column for some period of time using a leach solution containing 6-8 g/l Fe, replacement leach solution with a solution containing only 2-3 g/l Fe for a short period of time and the final return to the initial concentration of Fe is equal to 6-8 g/l (Figure 10) with the simultaneous determination of the degree of dissolution of Mo and activity of microorganisms under these changing conditions. And in this case, the inoculum of microorganisms for the experiment pre-adapted using the column described above. First, the concentration of soluble Mo exceed 600 mg/l after 40 days, when the concentration of iron in the leaching solution exceeded 5.5 g/l (Figure 10, 11). This was accompanied by a decrease of the redox potential of the solution is equal to 82 mV between day 37 day 40 without the simultaneous precipitation of Fe (arrow on Fig). The reduction potential of the solution showed that cells of microbes that oxidize Fe, whereas the features of the solution was achieved, the maximum level of toxic effects Mo.
A significant change occurred when the concentration of Fe in the leachate solution was reduced to 2-3 g/l (Figure 10) at day 40. Dissolution of molybdenum reached a plateau at about 237 mg/l (day 63). Then the potential of the solution was decreased to 57 mV from day 65 to day 68 (marked by an arrow on Fig). The decrease in redox potential in the absence of any explicit precipitation of Fe showed that in column ingibirovany microbial activity, oxidizing Fe, but at a much lower concentration of Mo. Resistance of microorganisms to the effects of Mo had actually decreased by about 61%. Containing little Fe leaching solution was re-replaced by containing 6-8 g/l Fe. By increasing the concentration of iron in the solution to the previous value (6006-7500 mg/l) led to circulation patterns. The concentration of Mo in the leaching solution was reached 494 mg/l at day 94 at high potential solution (>900 mV).
From these results it is clear that the persistence of populations of mesophilic microorganisms to the effects of Mo in the leaching solution depends on the concentration of Fe and beyond their physiological adaptation. The optimal molar ratio of Fe:Mo was approximately 20:1. This attitude to some extent may depend on the concentration of other components of the solution, such as copper, bisulfate and phosphate.
WHEN IS EP 8
It was interesting to demonstrate the capabilities of biological oxidation of molybdenite (MoS2) in the waste under mesophilic conditions. Used column configuration, simulating the blade, 1.5 meters
Preparation of solid loading. Raw download was a mixture of solid fractions, which is a separate flows boot process line processing of chalcopyrite (CuFeS2). The raw mixture contained 5,22 % Mo, 14.6% of Cu, 14.2% of Fe and 19.4 per cent of total sulfur and consisted of particles with a size of 5-50 μm. However, due to the high content of Cu this mixture was pre-processed held by first re-grinding and subsequent biological leaching columns in moderately thermophilic conditions (~50°C) to remove part of chalcopyrite component. The content of chalcopyrite in the loading was reduced to reduce competition for ferric ions in the leach solution from the sulphides of copper and molybdenum, which allows the system to operate at higher redox potentials required for biological leaching MoS2. After this microbiological pre-treatment solids, of which are partially removed copper, extracted, dried and determined the residual mineral content and the content of the metal is in and sulfur. Analysis of the first fraction extracted solids (moisture content of 0.36%) resulted in the following values: 6,45% Mo; of 3.46% Cu; 5,2% Fe and 12.11% total sulfur. In addition to molybdenite and chalcopyrite analysis of the DRA/romance-Germanic indicated the presence of quartz (40-50%), talc (14%), jarosite (<10%), sulfur (<5%), pyrite (<3%) and unidentified substances (<5%).
Agglomeration and loading column. Because of the small size of the particles to ensure the permeability of the column loading of molybdenite was necessary to glomerulopathy with local breeds. Local breed (-3+6 mesh) before use washed with 1 N. a solution of H2SO4. The wash solution was decanted and discarded. Then the solids washed successively with tap water and deionized water before use dried.
Approximately 6 kg was used as the lower drainage layer in a column with a diameter of 0.15 M. this layer was placed 28 kg local breeds, agglomerated with a 3.5 kg load of molybdenite, which partially removed copper that was an active layer, 1.5 meters 0.85 kg of the Local breed was used as a covering layer in order to facilitate more uniform distribution applied to the surface of the leach solution. To determine the temperature in the covering layer was inserted thermistor with the water jacket.
The work column. Used partieswith leach solution of the following composition: 16 l of deionized water, 128 ml 11 N. H2SO4, 1,60 g (NH4)2SO4and 600 g of FeSO4·7H2O that match the initial concentration of Fe(II)equal to 7500 mg/L. Aerating flow and leaching solution used in the standard counter-current mode at room temperature (23-34°C). Leach solution was continuously applied from a reservoir in the upper part of the column using a multichannel peristaltic pump at a speed equal to 0,002-0,003 gallon·ft-2·min-1Before inoculation the contents of the filled column during the night washed leach solution and added additional number 11 N. sulfuric acid required to establish the pH of the solution equal to below 2.5. After inoculation via the side channel in the lower part of the drainage layer was applied to the air. If in the beginning for air supply used one channel, then added a second channel to separate thread to avoid interrupting the flow of air when driving one channel due to evaporation of salts. The total air flow constantly was 4 l/min Flow coming from the column was collected in a receiving tank. For leach solution on an almost daily basis was determined by pH, redox potential, the content of Mo, Fe, Cu, SO42-, Si, CA, K and Mg. Periodically in the leaching solution was determined by the content RHO43- 4+. Periodically selected special samples for the determination of Al, As, Bi, Co, Cr, Cl-total organic C, Na, Ni, Mn, total N, Pb, Re, Sb, Sc, Se, Ti, Tl, U, V, W, Y, Zn and Zr.
The inoculation. The original inoculum contained combined biomass collected after completion of the previous experiments on columns, which conducted biological leaching MoS2. The biomass was separated from the solid residues by mixing in the leaching solution and by gravity separation of solids separated from suspension cells. This biomass was combined with biomass collected previously, and until further use froze.
Demonstration column was inoculable actively growing cells derived from frozen initial inoculum. 250 ml of suspension adapted to the IO cells were mixed with an equal volume of 0,1X 9K basic solution of nutrient salts and added 3.7 g/l Fe(II), in the form of FeSO4·7H2O, 1% wt./about. FeS2and 0.5% wt./about. So. The cultures were incubated statically at 25-30°C is carried out by blowing aeration until the cells are not actively oxidize the iron. During inoculation, the culture had a redox potential that is equal 919 MB (BOO), and the concentration of suspended cells, equal to 2.2×108cells/ml Total 500 ml of this culture was administered to the upper part of the layer in the column using a peristaltic pump with a standard speed.
The treatment solution. To regulate the concentrations of Cu and Mo in the solution during the leaching cycle used different strategies. Although subjected to preliminary processing to download still contained a certain amount of chalcopyrite. Removal of copper from circuit leach solution, the contents of tank leach solution once was partially replaced with fresh medium (day 39) and several times was replaced completely (days 16, 28 and 42). In addition, the availability of nitrogen was improved by adding ammonium sulfate (is 3.5 mg/l NH3in tank leach solution. At day 28, when 3,75% is contained in the download the Mod was solubilisation, to the return line leach solution was added loop circuit, which contains a module with resin MR to remove the Mod from the solution before returning to the tank. However, at day 44 (solubilizers 11,1% Mo) began using closed loop and it was used almost exclusively during the remaining phases of dissolution of molybdenum. Leaching solution is not replaced periodically, and continuously recycled. However, during use of the closed cycle twice added nutrients (NH3-N and RHO43-designed to ensure a sufficient supply of microbial populations nitrogen and phosphorus. These add the Cai resulted in concentrations of nutrients, the respective main Wednesdays, 0,H 9K. Almost daily selected samples of leach solution, and by the end of the column over the weekend took the combined samples, characterizing the flow for 3 days.
Removing the solids. After passed through the column just to 6.42 per l of 0.02 N. H2SO4for washing off the residual leach solution. Solids were removed from the column and was divided into four roughly equal sections to assess the biological oxidation on the height of the column. Selected 4 solid sample from the upper, middle and lower part and the lower drainage layer. Before the separation from agglomerated together local breeds from each section were selected by a small additional samples wet agglomerated material for use in the study included biomass (see below). Together agglomerated local breed and subjected to biological oxidation of the finely dispersed substance was separated by washing with tap water. Then the suspension was passed through a sieve with a mesh size of 2 mm for the separation of fine material and larger local breeds. After settling in for a night of fine substances slight excess water was separated by siphon and discarded. The remaining suspension was dried for 48 h at 60-70°C. the Dry solid is haunted substances homogenized manually weighed and divided into samples for subsequent decomposition and analysis. Each of these 4 solid residues was investigated using x-ray diffraction analysis (DRA) to determine the residual content of minerals, x-ray fluorescence (Philology Department) to determine the elemental composition, the content of total sulfur, sulfate, osadivshih metals, and decomposing and residual metals were determined using spectroscopy using EQ.
The study included biomass. Small amounts of washed agglomerated solids (< 20 g) were collected at the end of the column. Register the weight of the wet sample. The samples were immersed in the same volume OF 2 ΜM and was shaken for about 1 min Solids were allowed to settle for 5 to 10 minutes the resulting cell suspension was used for the standard analysis of the most probable number of cells with three holes. As the energy sources used ferrous iron and elemental sulfur. The analysis was performed at the microscale using a 48-hole tablet (used for the analysis of 1000 μl solution). The plates were incubated at room temperature (23-26°C) for 24 days and then determined the density of the population.
Chemical characteristics of the leach solution. As shown in Fig, the concentration of glands is in the leach solution during the greater part of the demonstration experiment exceeded 6 g/L. For approximately one week, the pH value of the stream exiting the column were exceeded 2.5 and to maintain the pH in the tank was added 11 N. sulfuric acid. After that, the system operated at a pH of from 1.3 to 1.6 (Fig).
The redox potentials of the sample stream exiting the column, shown in Fig. After 100 days of work a potential solution constantly exceeded 900 mV. Normalized (24 h) the dissolution rate of Mo is shown in Fig. The maximum rate is 0.9%/day, was observed at day 49 when the redox potential of the stream exiting the column, equal 779 mV, while in the upper parts of the layer was observed some zonation of microbial populations and possibly the understatement of the maximum speed and capacity of the solution. This is evidenced by the study of the composition of the zones of the solid residue, discussed below (see Table 9). The difference of Mo concentrations in leaching solution (the concentration in the stream included in the column minus the concentration in the stream leaving the column) was approximately 1 g/l Mo. The maximum observed daily rate of dissolution of Mo is also consistent with a change in the kinetics of dissolution of Cu, when the subsequent concentration of Cu in the solution is linearly increased with time.
The study of biomass according to the method of the most probable number showed that the soda is Jania included oxidants Fe were high in all sections of the column, that testifies against specific biological inhibition due to high local concentrations of Mo in systems with elevated concentrations with the proper regulation of Fe concentrations in the leaching solution. In addition, from Table 8 it follows that the biological oxidation of molybdenite are provided mostly by oxidizing iron microbial population, since populations, oxidizing S, contained in amounts of 2-5 orders of magnitude smaller than the oxidising Fe.
Biomass, included in a solid substance, extracted from the residues contained in the column
|Sample||The most probable number (cells/g wet)|
|Oxidising Fe||Oxidants S|
|Top||of 1.1×107||2.4 x 105|
|Average||> 2.4 x 107||2.4 x 105|
|> 2.4 x 107||7,5×102|
Operation in closed cycle covered the period of time for which almost 90% associated Mo passed into the solution (which corresponded to 70% of Mo contained in the downloadable material). Mass balance of Mo in solution and in the residues will result in table 9. One important fact was the change in the degree of biological oxidation along the length of the column. Despite the presence of comparable amounts included oxidants Fe, it appears that the degree of oxidation and copper (chalcopyrite), and molybdenum (molybdenite), was decreased when moving from the top of the column to the bottom. After making adjustments for the content of jarosite and gypsum in four samples of the contents of the column the estimated degree of dissolution Mo for each fraction were (top to bottom): upper (89%), average (84%), lower (76%) and lower/DS (70%).
The mass balance of the content of molybdenum and copper in the extracted solid residues
|Sample||The extracted residue (g)||The extracted residue %||% Mo1||%Cu|
|First fracc the I 5||6,45||of 3.46|
|1The metal content was determined using ICP-AES (atomic emission spectroscopy) after chemical decomposition (heating with HNO3H2O2, HCl) of the solid residue|
|2DS - drain layer|
|3 Considered to 96.6% by weight of Mo. The full content of Mo: solids - Mo, 49,586 g; leaching solution - Mo, 162,13 g; Mo: 211,72 g; the initial contents of the Mod in the download: 219,1 g; the initial contents of Cu loading: 117,6 g|
|5The results of the analysis of the first fraction of the load from which the partially removed copper: 6,45 % Mo; of 3.46 % Cu; 5,2 % Fe; 12,11 % total sulfur|
A comparison of the data for the dissolution of Mo in the small column of the same configuration data for the column with a layer length of 1.5 m, which corresponds to a scale of about 45 X (Fig). The dissolution of Mo in the large column was a little better.
The influence of the concentration of Fe(III) in biological leaching of molybdenite. Studies in flasks with shaking detected speed increase biological leaching of molybdenite at higher concentrations of dissolved iron. They were placed with 0.2% (wt./wt.) containing molybdenite three-component composition, from which it is removed, the copper in the leach solution initially containing 2.5 g/l Fe(II) in the form of sulphate ferrous iron (same bulb 13 and 14) or 0.5 g/l Fe(II) (bulb 15 and 16). After inoculation and 50 days biological leaching, extraction of Mo ranged from 53 to 56% in flasks 13 and 14, but only from 4 to 41% in the tubes 15 and 16. Less extraction tubes 15 and 16 correlates with a lower redox potential of the solution than in flasks 13 and 14. Although during the biological leaching of Mo redox potentials were relatively high in all 4 flasks (>850 MB BOO or >99% iron in the form of Fe (III), the potentials in flasks 13 and 14 were always about 50 mV higher than in tubes 15 and 16. This indicates that the microorganisms are better able to maintain a high redox potential of the solution at higher concentrations of dissolved iron.
However, the favorable effect of higher concentrations of dissolved iron is not necessarily true in the case of the much higher concentrations of dissolved Fe, as evidenced by the data for flasks with shaking Mg-1 and Mg-2. In this case, the rate of biological leaching of Mo from the three-component compositions (0.6% of solids) in flasks, initially containing 6 g/l Fe(II) and 12 g/l Fe(II) (Peg), were almost identical. The redox potentials of the solutions were also close and was >900 mV. It seems that, if dissolved Fe(III) is contained at a concentration exceeding a certain threshold value, the concentration is not critical for the biological leaching of molybdenite.
From these studies in flasks with shaking, the concentration of Fe(III), aunie from 2.5 to more than 20 g/l, are optimal for biological leaching of molybdenite, provided that the redox potential of the solution are also high. It seems, however, that the threshold concentration change when the flow rate of trivalent iron. It affects the amount of molybdenite and other sulfide minerals.
In addition, the influence of the ratio of ferric to the amount of molybdenum in biological leaching of molybdenite. Ferrous iron (6 g/l) were subjected to biological oxidation when added together with the dissolved Mo (from 2.7 to 2.8 g/l) to the solution containing 11.3 g/l of trivalent iron. This corresponds to a molar ratio of Fe(III):Mo, approximately 7:1. Biological leaching of molybdenite was at 4.4 g/l of dissolved Mo in high ORP (860 mV BOO) solution containing 18 g/l Fe - also at molar ratio Fe(III):Mo, approximately 7:1. In contrast, divalent iron (4 g/l) was not subjected to biological oxidation when added together with 1.1 g/l Mo to a solution containing 3 g/l Fe(III) molar ratio of Fe(III):Mo average of 4.7:1. The ratio of Fe(III):Mo is important for biological leaching of molybdenite, because the presence of Fe(III) reduces the toxic effect of Mo on microorganisms, biologicallyactive ore. From these studies in flasks with shaking it follows that the molar ratio of Fe(III):Mo in the solution of about 7:1 or more is optimal to reduce the toxic effects of Mo, which provides the possibility of biological iron oxidation and subsequent biological leaching of molybdenite. In contrast, the ratio of Fe(II):Mo is not so important, since it is established that Fe(II) does not protect cells from the toxic effects of Mo. In the absence of significant concentrations of ferric Mo suppresses the biological oxidation of Fe(II). For example, 6 g/l Fe(II) was not subjected to biological oxidation in the presence of 0.1 g/l Mo at molar ratio Fe:Mo average of more than 100:1.
When research on biological leaching column studied the effect of Fe concentrations in the leaching solution and the molar ratio of Fe(III):Mo on biological leaching of molybdenite. It was impossible to disentangle the effects of concentrations of Fe and effect relationship of Fe(III):Mo in leach solutions. The presence of approximately 6 to 7 g/l of trivalent iron in the leaching solutions (high redox potential) provides leaching to approximately 600 mg/l of dissolved Mo from molybdenite, agglomerated with the base rock to the manifestations of toxic effects Mo. When this molar ratio Fe:Mo is approximately 20:1. PR is smaller concentrations of trivalent iron (2.5 g/l), lower plateau concentrations of Mo, accumulated to the inhibition of microorganisms dissolved Mo (0.2 g/l), corresponds to approximately the same molar ratio (20:1). These plateaus are associated with inhibition of microbial iron oxidation of dissolved molybdenum and characterized by the need for the presence of certain concentrations of Fe(III) to prevent the toxic effects of Mo in columns (Fig and 20).
For column 5 also detected plateau extract the Mod in leaching solutions, which increase with increasing concentrations of dissolved Fe(III) and also corresponds to the molar relationship of Fe(III):Mo in the solution of about 20:1 (Fig). Although iron was added to the system in the form of sulphate ferrous iron, its oxidation to ferric iron by microorganisms was critical for biological leaching of molybdenite and to improve the resistance of dissolved Mo.
Summarizing, we can say that research led to the conclusion that a higher ratio of Fe(III):Mo (20:1)than in studies in flasks with shaking (7:1) to prevent the toxic effects of Mo on microorganisms and to ensure the biological leaching of molybdenite. This difference is probably due to the greater number of solids to kolichestvennoe in columns compared with the ratio in flasks with shaking.
1. The method of extraction of molybdenum sulfide material containing molybdenum, comprising the stage of: (a) interaction of the material with an acidic leach solution in the presence of at least one compound of iron and acidophilic microorganisms, at least, able to oxidize ferrous iron, and (b) leaching, wherein stage (b) leaching is carried out at regulation molar ratio of dissolved ferric iron to dissolved molybdenum and set it equal to at least 6:1, preferably at least 7:1 and after leaching is carried out stage (C) extraction of molybdenum, at least one of solid and liquid residues leaching process.
2. The method according to claim 1, characterized in that the material is a containing molybdenum sulfide mineral.
3. The method according to claim 1, characterized in that the compound contains iron ferrous iron or ferric iron, preferably a sulfide containing divalent iron ions of ferrous iron or ferric ions.
4. The method according to claim 3, characterized in that the trivalent iron is used at a concentration equal to from 0.5 to 40 g/L.
5. The method according to claim 1, characterized in that the compound of iron is a ferrous sulfate iron or sulfate travelintelligence, preferably the sulfate ferrous iron in solution.
6. The method according to claim 1, characterized in that the compound of iron is a sulfide mineral containing divalent iron, preferably pyrite.
7. The method according to claim 1, characterized in that it includes a preliminary cultivation of microorganisms in a culture medium containing divalent iron is carried out before stage (a).
8. The method according to claim 1, characterized in that the microorganisms are of the mine water.
9. The method according to claim 1, characterized in that the microorganisms are mixed culture containing at least one mesophilic, moderately thermophilic and extreme thermophilic microorganisms, preferably mesophilic microorganisms.
10. The method according to claim 9, wherein the mesophilic microorganism selected from the genera Leptospirillum, from acidithiobacillus, Ferroplasma and Ferrimicrobium, preferably Leptospirillum, including at least one of the strains of L. ferrooxidans and L. ferriphilum.
11. The method according to claim 10, wherein the process is carried out at a temperature of from 20 to 42°C, preferably at 40°C.
12. The method according to claim 1, characterized in that the process is carried out at a pH of 2.0 or less, preferably at pH from 1.2 to 2.0.
13. The method according to claim 1, characterized in that the process is carried out at a redox potential that is equal to at least 700 mV.
14. The way is about to claim 1, characterized in that the process is carried out at the concentration of dissolved molybdenum, less than or equal to 4.4 g/l
15. The method according to claim 2, characterized in that the mineral has a particle size less than 50 microns, preferably less than 15 microns.
16. The method according to claim 2, characterized in that the mineral has a specific surface area equal to at least 3 m2/g, preferably at least 10 m2/year
17. The method according to claim 1, characterized in that in stage (b) molar ratio monitor in continuous mode.
18. The method according to 17, characterized in that the molar ratio monitor directly by determining the concentration of dissolved ferric iron and dissolved molybdenum and their correlation.
19. The method according to p, characterized in that the concentration was determined by spectroscopy with inductively coupled plasma.
20. The method according to 17, characterized in that the molar ratio monitor indirectly by determining the redox potential of the sediment.
21. The method according to claim 1, characterized in that in stage (b) load connection of iron.
22. The method according to claim 1, characterized in that in stage (C) the molybdenum is extracted using at least one of the following technologies: precipitation, ion exchange, solvent extraction and electrochemical extraction.
23. The method according to claim 1, characterized in that including the AET phase extraction sulfide, containing heavy metal, when the redox potential equal to less than 700 mV, from material to stage (a).
24. The method according to item 23, wherein the sulfide is removed by applying to the material of the pre-leaching and removal of heavy metal from the leached residue of the pre-leaching.
SUBSTANCE: procedure consists in purification of solution of ammonia paramolybdate form impurities by ion exchange in neutral and sub-alkali mediums on hydrated oxide of tin and on sub-basic anionite AN-106. Further, ammonia paramolybdate is thermally decomposed at temperature 600-800°C to production of molybdenum oxide and is refined by zone sublimation at temperature 750-800°C in continuous flow of oxygen. Molybdenum oxide is heterogeneous reduced with hydrogen at temperature 700-750°C till production of powder of molybdenum. Powder is compressed to a rod which is subjected to electronic vacuum zone re-crystallisation till production of high purity molybdenum crystal. Molybdenum crystals are melt in electron vacuum in a flat crystalliser with melt of flat ingot of high purity molybdenum on each side at total depth not less, than twice. A molybdenum rod is treated with chlorine prior to zone re-crystallisation at rate of chlorine supply 100 ml/min and temperature 300°C during 1 hour.
EFFECT: great rise of molybdenum purity.
SUBSTANCE: according to the first version there is used preliminary mixed charge containing components at following ratio, wt %: molybdenum concentrate 69, reducer 31. Thermal treatment is carried out in a graphite can at temperature of combustion 1400-1600°C during 10-15 min. According to the second version there is used preliminary mixed charge containing components at following ratio, wt %: molybdenite concentrate 53-55, reducer 15-17, iron containing compounds 25-27, slag forming components 3-5. Thermal treatment is performed in the graphite can at temperature of combustion 2000-2200°C during 30-40 min.
EFFECT: efficient and ecologically safe thermal process of production of molybdenum and its alloys.
6 cl, 1 tbl
SUBSTANCE: procedure for extraction of molybdenum (VI) from solutions of cations of heavy metals consists in sorption of molybdenum (VI) at value of pH of solution less, than value of pH of hydrolytic sedimentation of cations of heavy metals. As sorbent at sorption there is used activated bone coal.
EFFECT: raised efficiency of procedure.
2 tbl, 2 dwg, 2 ex
SUBSTANCE: procedure for production of metal powder of molybdenum consists in reduction of molybdenum oxide (MoO3) with metal-reducer in melt of sodium chloride of potassium chloride or their mixture at ratio 1:1 at temperature 770-850°C. Upon reduction metal phase of molybdenum powder is separated from reaction mass. Reduction is performed with aluminium powder at ratio of source molybdenum oxide (MoO3) to melt equal to 1:3-5.
EFFECT: reduced temperature of melting at sufficiently complete extraction of molybdenum from oxide in form of metal high dispersed powder of molybdenum and reduced consumption of reagents.
SUBSTANCE: production of Mo-99 consists in filling solution reactor with fuel solution of uranyl-sulphate, in starting reactor up to specified power, in forming Mo-99 in fuel solution, in reactor shut-down, in conditioning fuel solution for decay of short-lived radionuclide and in sorption of Mo-99 from solution. Also, after reactor shut-down fuel solution is poured out of the reactor into at least one nuclear-safe reservoir; fuel solution is conditioned in this nuclear-safe reservoir. An empty reactor is repeatedly filled with fuel solution, is started up to specified power and Mo-99 is repeatedly generated in fuel solution. For the period of Mo-99 generation in the fuel reactor poured fuel solution in the nuclear-safe reservoir is conditioned. Mo-99 is sorbed from conditioned fuel solution by pumping it through at least one sorption column wherefrom Mo-99 is sorbed into at least one nuclear-safe reservoir for fuel solution conditioning. Fuel solution is conditioned, if necessary. Repeatedly emptied reactor is filled with fuel solution from the nuclear-safe reservoir for fuel solution conditioning.
EFFECT: raised efficiency of solution reactor producing Mo-99 under discrete mode due to reduced idle time.
9 cl, 1 dwg, 1 ex
SUBSTANCE: procedure consists in extracting uranium by means of liquid extraction of organic phase of synergy mixture on base of di(2-ethylhexyl)phosphorous acid containing tributylphosphate (TBP) or tributylphosphate together with trialkylamine (TAA) or heteroradical phosphynoxide of composition of oxide of isoamyldioktylphosphyne in organic thinner. Also, while mixing, there is performed simultaneous gradual neutralisation of mixture of phases with mineral acid till there are established balanced values of pH of water phase in interval 5.6-6.6.
EFFECT: increased efficiency of extraction of uranium and molybdenum from carbonate solutions.
3 dwg, 3 tbl, 3 ex
SUBSTANCE: procedure for hydro-metallurgical treatment of rhenium containing molybdenite concentrate consists in rhenium and molybdenum autoclave leaching with solution of nitric acid and in producing solution containing nitric and sulphuric acids. Further, residue in form of molybdenum acid is filtered and washed; molybdenum acid is dissolved in ammonia water and molybdenum and rhenium are extracted. Upon autoclave leaching rhenium is extracted from solution by sorption in two stages. At each stage duration of phase contact is 22-24 hours. Summary concentration of sulphuric and nitric acids at the first stage is maintained at ≤120 g/l and pH value at the second stage is maintained at 2-4. Molybdenum is extracted from a merged solution produced from the solution after sorption extraction of rhenium and from ammonia solution of dissolved molybdenum acid. Molybdenum is extracted by sorption in two stages at duration of phase contact 22-24 hours and maintaining pH value=1.5-2.0 at the first stage and pH=2.5-4.0 at the second stage.
EFFECT: increased output of molybdenum and rhenium into finish products, their high quality, simplification of process and its raised efficiency.
SUBSTANCE: method involves mixing concentrates with additives selected from MgO, MgCO3, CaO, CaO2, CaCO3, BaO, BaO2, BaCO3 in amount of 100-120 % of the stoichimetrically required for bonding sulphur. The concentrates then undergo oxidising roasting at 450-650°C for 30-90 minutes and the obtained ash is leached with a solution of an alkali metal carbonate with concentration of 150-250 g/dm3. The alkali metal carbonate used is sodium carbonate or potassium carbonate. After leaching, molybdenum and rhenium are extracted from the solution.
EFFECT: higher extraction ratio of molybdenum with concomitant extraction of rhenium.
4 cl, 1 tbl, 1 dwg, 1 ex
SUBSTANCE: invention relates to hydrometallurgy, particularly to extraction of uranium and molybdenum from carbonate ores. Method includes crushing, grinding and high-volume sorptive leaching at presence of oxidants. Additionally after 2-4 stage of sorptive leaching of uranium and molybdenum into pulp there are introduced KMnO4 at its consumption 0.15-0.25% of ore mass and it is implemented after-oxidation of uranium and molybdenum during 40-60 minutes at absence of sorbent. After after-oxidation it is finished sorptive leaching.
EFFECT: reduction of oxidant consumption and total process duration.
2 tbl, 2 ex
SUBSTANCE: group of inventions relates to extraction of molybdenum from acid liquors, containing mixture of nitric and sulfur acid and molybdenum in wide range of concentration and also other admixtures and can be used at regeneration of molybdenum from waste colution for etching of molybdenum cores in manufacturing of electric bulbs and electronic devices and solutions of hydrometallurgy manufacturing. Extraction of molybdenum is implemented from solutions with diferent content in it of molybdenum. Acid solution is treated by electromagnetic field with frequency selected in the area of mid-range radio waves, formed water is driven off, laid-down sediment is filtered. Extracted acid is returned into etching process. Installation includes reactor block, filtration unit, tanks for solutions, pipelines, stop and variable valves. Reactor block includes reactor, electromagnetic field generator, inductor and matching device. Inductor is located inside or outside thru reactor. Installation additionally contains rectifying still for distillation of water, direct connected to reactor.
EFFECT: increasing of extraction ratio subject to circulation of colutions, process is ecologically safe, industrial sewages are not formed.
7 cl, 1 dwg, 2 tbl, 2 ex
SUBSTANCE: in invention claimed are devices and methods for continuous anti-current desorption of target materials. Device for substance desorption from ion-exchange resin which has sorbated on it admixtures and target materials, includes first and second chamber. Resin is supplied into first chamber, and is transported from first chamber to second chamber, and desorbing solution is supplied into second chamber, and is transported from second chamber into first chamber. Admixtures, which have less affinity with resin, than target material, can be desorbed from resin, and target material can be sorbed on resin from desorbing solution in first chamber. Flow of admixtures, which has high admixture concentration and relatively low concentration of target material, is released from first chamber through first outlet. Target material is desorbed from resin in second chamber, and enriched flow, which has low admixture concentration and relatively high concentration of target material, is released from low parts of first and/or second chamber through second outlet.
EFFECT: extension of arsenal of means for substance desorption from ion-exchanging resin.
41 cl, 6 dwg, 1 tbl, 5 ex
FIELD: process engineering.
SUBSTANCE: invention relates to concentration of rare-earth metal and tin ores. Proposed method comprises primary flotation by oxyhydril collector to produce crude concentrate, concentrate thickening and directing it to cleaner floatation. Liquid bacteria Bacillus mucilaginosus in amount of 10-20 ml per 1l of concentrate is added to thickened crude concentrate pulp to be held out for at least 3 days and directed to cleaner flotation to be conducted at pH of at least 6.
EFFECT: higher yield of valuable components.
SUBSTANCE: procedure for extraction of metals from silicate nickel ore consists in preparation of silicate nickel ore by crushing and classification, in silicon leaching from ore with cultural medium of silicate bacteria and in successive extraction nickel from cake. Silicate minerals of ore are bio-degraded at leaching silicon with cultural medium of silicate bacteria; bio-degradation is performed at pH as high, as 4, without mixing and with replacement of cultural medium. Nickel is extracted from cake of bio-degradation by leaching with utilisation of solution of bio-degradation upon silicon has been extracted from it and by adding sulphuric acid to concentration 50÷450 g/l. Further, metal is extracted from leaching solution of cake bio-degradation.
EFFECT: increased extraction of nickel from silicate ore, raised rate and efficiency of silicate nickel ore leaching.
7 cl, 2 ex
SUBSTANCE: procedure consists in four-stage bio-oxidation of sulphides with supply of air into bio-pulp of concentrate at flow of bio-pulp through reactors. Bacterial oxidation is performed in bio-pulp containing 7.5-10 % of solid at specific rate of bio-pulp flow (5-7.8)·10-2 m3/m3 per hour and supply of air at amount required for oxidation of S2- to S4+, while iron (II) and arsenic (III) to higher degrees of valence. Also, flow rate of air by stages of bacterial oxidation amounts to %: 80-85 - at the first, 8-10 at the second, 4-6 at the third and 3-4 at the fourth stages.
EFFECT: raised engineering-and-economical performance of process and reduced air consumption.