The method of refining magnesium scrap
(57) Abstract:The invention relates to ferrous metallurgy and can be used in the processing of magnesium scrap. The method of refining magnesium scrap includes the melting of scrap in the environment of the molten flux certain density and sedimentation, and the melt before settling further treated by air under pressure in the range of 0.03-0.6 MPa and served under a layer of melt in dispergirovannom, supporting the specific air flow rate in the range of 0.1 to 100.0 cm3/(kgf), and the density of the molten flux is kept lower than the density of solid scrap, but higher than the density of secondary molten metal with respect to the mass of molten flux to the mass of recycled scrap in the range of 0.08 to 3.5. In addition, the melting is carried out at a temperature of melt 700-780°C in the molten flux of the following composition, wt.%: 45-58 KS1, 8-19 NaCI, 18-31 MgCl2, 4-12 BaCl2, 0-2,0 l2, 0-5,0 CaF2, 0-1,5 gF2. The melt is treated with metallic magnesium in an amount of 0-3% of its mass, is achieved by increasing the degree of extraction of the metal. 8 C.p. f-crystals. The invention relates to ferrous metallurgy and can be used in the processing of magnesium RCDs.with ang. M: Metallurgy. - 1972. - S. 488) the number of ways to extract the metal from various forms of magnesium scrap.Large magnesium scrap is processed by melting, and in any ratio. This technology is obvious and does not require improvement.Scrap covered by corrosion, by direct fusion gives a dry crucible residue, which reduces the degree of extraction and degrades the quality of the secondary metal.Small chips, it is recommended to add together with flux in continuously stir the bath at a temperature close to the liquidus temperature. After melting of the entire chip temperature raise and produce clean flux. However, experimental validation of the method showed that the thus obtained secondary metal is extremely dirty magnesium oxide, and its output is low due to heavy smoke in the first stage of processing. The same applies to the melting of sawdust and powder. Therefore, these types of scrap, usually buried in the ground or destroyed by burning.For crucible residues proposed the following processing methods:
a) melting the "rich" residues with a protective flux and mixing for sintering metal;
b) raznogo alloy;
C) mechanical disintegration with sorting of waste rock;
g) wet disintegration by flushing flux and release of metal;
d) centrifuging crucible residues.However, all these methods have significant drawbacks. For example, the method "a" allows for the melting of partially removing the metal, which is then usually broken into small drops under stirring of the melt. In addition, the mixing leads to resuspension of magnesium oxide, which is adsorbed on the droplet surface, weight and forces them to fall in the slurry zone. Methods "b", "C" and "d" allow to extract the metal in the form of a coated oxide-salt film granules of very low quality. Method "d" can be extracted, usually not more than 50% of the metal contained in the waste. This is because the metal in the waste is mainly in the form of fine drops (diameter less than 2 mm), covered with a durable oxide film. Given that the density of magnesium oxide (3.6 g/cm3in two and a half times greater than the density of molten magnesium (~ 1.56 g/cm3and about twice the flux density (1.6 to 1.8 g/cm3), the formal density drops (weight of magnesium oxide and magnesium in the droplet volume) becomes comparable with Y.The closest and most effective way to the same destination to the claimed invention, a combination of traits, selected as a prototype, is a method (U.S. Pat. N 1480360, action, 28.07.94) metallurgical processing of magnesium-containing waste, including smelting waste in the environment of flux and sedimentation. And smelting waste is carried out at 730-760oC in an environment of flux density lower than the density of the melt waste at the rate of flux 8-10% by weight of the waste and subsequent processing of calcium fluoride when the flow rate of 1-2% by weight of waste. The method is very effective, cheap and allows you to extract up to 70-74% of the metal contained in the waste. The resulting metal fully complies with the technical requirements for secondary magnesium alloy and can be used without further processing as a charge component in the production of standard magnesium alloys.The main disadvantage of the prototype is not a high degree of extraction of the metal, due to the impossibility of removing it from the small, covered with a durable oxide film of metal drops.The task on which the invention is directed, is to increase the degree of extraction of the metal due to the inclusion in ne is in the method of refining magnesium scrap, including the melting of scrap in the environment of the molten flux certain density with a melt and defending, what's new is that the melt before settling further treated by air under pressure.In addition, the excess pressure is maintained within the range of 0.03-0.6 MPa.In addition, the air supplied under a layer of melt in dispergirovannom.In addition, the specific flow rate of air is maintained within the range of 0.1 to 100.0 cm3/(kg).In addition, the density of the molten flux is kept lower than the density of solid scrap, but higher than the density of secondary molten metal.In addition, the ratio of the mass of molten flux to the mass of processed scrap is maintained within the range of 0.08 to 3.5.In addition, the melting is carried out at a temperature of melt 700-780oC.In addition, the melting lead in a molten flux of the following composition, wt. %: KCl 45-58, NaCl 8-19, MgCl218-31, BaCl24-12, CaCl2- not more than 2.0, CaF2- not more than 5.0, MgF2- not more than 1.5.In addition, the melt is treated with metallic magnesium in an amount of not more than 3% of its mass.The choice of these terms of refining magnesium sadamasa on the metal surface as in the solid scrap, and small drops of molten metal in the scrap, there is always a silicide of magnesium (Mg2Si), which falls into the metal at the stage of electrolytic production of magnesium by its interaction with silicon oxide, which is part of fireclay pot lining
SiO2+ 4Mg = Mg2Si + 2 MgO (1)
In some special studies, we experimentally proved that the presence of magnesium silicide promotes the oxide film, which is not destroyed even in the presence in the melt of such well-known depassivation as CaF2and MgF2. As a consequence, there are ways to recycle scrap, including the way the prototype, allow to extract from the waste only metal in the melt in the form of relatively large units ("pots"), not covered with the oxide film. Such a metal in liquid metallurgical wastes, as a rule, is about 70%. This explains the corresponding degree of metal extraction from liquid metallurgical wastes in the method of the prototype. About 30% of the material placed in such waste in the form of small (diameter less than 2.0 mm), covered with an oxide film of metal drops, unable to extract. The same result is almost always education, or digging in the earth.We experimentally found that to extract the metal from the small, covered with a durable oxide film drops can be used for a treatment of the melt with air. This is because the silicide of magnesium in the interaction with air moisture intensively decomposed:
Mg2Si + 2H2O = SiH4+ 2MgO (2)
with the formation of magnesium oxide and silane.The latter, in turn, decomposes into silicon oxide and water:
SiH4+ 2O2= SiO2+ 2H2O (3)
which is partly re-involved in the interaction with magnesium silicide by reaction (2), and partially consumed by the decomposition of silane:
SiH4+ 2H2O = SiO2+ 4H2. (4)
As a result of this rapidly flowing process of the oxide film on the surface of droplets of the metal is destroyed, and the released droplets of metal in the coalescence merge into a compact mass, suitable for its separation from oxide molten salt known methods.It is shown that, depending on the thickness of the metal-oxide-salt melt and the viscosity of the air should flow at a pressure of 0.03-0.6 MPa.When this lower limit is due to neobjevena melt.For a more uniform flow of process depassivation of metal drops in the volume of the melt, the air must be submitted under a layer of melt in dispergirovannom the form of, for example, through various spray devices.The specific flow rate of air should be maintained in the range of 0.1 to 100.0 cm3/(kgf). It was established experimentally that at a flow rate below the lower limit of the process of depassivation drops proceeds slowly and the released droplets of metal, unable to merge, covered with a new oxide film - a compact mass of metal is not formed.When the air flow is above the upper limit, the process proceeds very rapidly, as a consequence, the fused metal is again divided into small granules.To create conditions favorable for metal recovery from scrap, melting is carried out in the molten flux, the density of which is lower than the density of solid scrap, but higher than the density of secondary molten metal. In this case, the loaded waste pass through a layer of molten refining flux, cleaned of excess oxides, and the initial stage of their melting takes place under the flux layer, which reduces metal loss on the fumes in the furnace. After melting and release from oxt, forming a compact mass.It is found experimentally that for the successful completion of the separation of melting a mass of molten flux to the mass of recyclable scrap must be maintained in the range of 0.08-3,50. When the ratio below the lower limit of the amount of flux is insufficient for cleaning metal and the latter are heavily polluted with non-metallic impurities (oxides, chlorides, fluorides, and so on). The increase in the ratio over 3,50 not economically feasible, because it does not increase the purity of the metal, or to increase the degree of extraction from scrap.It was established experimentally that the heat should be carried out at a temperature of melt 700-780oC in the molten flux of the following composition, wt.%: 45-58 KCl, 8-19 NaCl, 18-31 MgCl2, 4-12 BaCl2, 0-2,0 CaCl2, 0-5,0 CaF2, 0-1,5 MgF2. In the specified temperature range the flux of this compound provides good cleaning of metal from non-metallic inclusions, primarily from fragments of the oxide film. In addition, in this temperature range the flux has good fluidity and the desired density. When drops of metal after they depassivation converge very slowly, which is possible when bol is TBE "seed" in the melt add magnesium metal in an amount up to 3% by weight of the melt.Conducted by the applicant's analysis of the prior art, including searching by the patent and scientific and technical information sources and identify sources that contain information about the equivalents of the claimed invention, has allowed to establish that the applicant had not discovered analogues characterized by signs, identical all the essential features of the invention. The definition from the list of identified unique prototype, as the most similar set of features analogue, has allowed to establish the essential towards perceived by the applicant to the technical result of the distinctive features in the proposed method, set forth in the claims. Therefore, the claimed invention meets the condition of "novelty."To verify compliance of the claimed invention the term "inventive step", the applicant conducted an additional search of the known solutions to identify signs that match the distinctive features of the prototype of the characteristics of the claimed method. The search results showed that the claimed invention not apparent to the expert in the obvious way from the prior art because the prior art defined by the applicant, not to identify the Oia technical result. Therefore, the claimed invention meets the condition of "inventive step".Experimental validation of the proposed method were carried out in industrial conditions on the existing technological equipment.Example 1. Clean scrap crucible installed in a shaft furnace CMT-2, melted 400 kg flux of the following composition, wt.%: 50 KCl, NaCl 15, 20 MgCl2, 8 BaCl2, 2 CaCl2, 4 CaF2, 1 MgF2. The flux of such composition at a temperature of 700-750oC has a density 1,68-1.66 g/cm3. The melt was heated to 750oC and portions of 100-200 kg in the crucible loaded 1500 kg briketirovannogo chip magnesium alloy MA-1. Solid chips alloy MA-1 has a density of approximately 1.77 g/cm3so after you download it fell under the layer of the melt, the metal melted and the temperature was raised to 750oC. the density of the alloy at this temperature is approximately 1.64 g/cm3, i.e., the metal became easier flux and was able to float on its surface. However, the "apparent" density drops of metal (mass of metal and oxide films in the droplet volume) is comparable with the density of the flux (rate of 1.67 g/cm3), and therefore the bulk of the metal in the form of droplets coated with oxide film, stuck in tol the VA was not detected. Attempts to extract the metal by mechanical stirring of the melt and further processing fluorides of calcium and magnesium did not lead to success. Then the crucible was installed a steel tube connected to the compressed air and equipped with device for spraying. Spent processing the melt for 20 min, feeding compressed air to the bottom of the crucible under a pressure of 0.1 MPa at specific discharge 1.65 cm3/(kgf). The metal after treatment were merged into a compact mass, and separated from the oxide molten salt using the wall for flow of metal. Weighing showed that the extracted 1365 kg of recycled magnesium alloy, i.e., the degree of recovery was 91%.Example 2. The experiment was carried out as described in example 1. The difference was that the ratio of the mass flux to the metal experience was 3,79, because the mass flux of 1500 kg, weight briketirovannogo, strongly oxidized chip - 400 kg After melt processing compressed air metal on the surface of the melt in the CD was missing. In the crucible was added 50 kg of magnesium raw and processed melt compressed air for 3 minutes After 10 min of sludge from the crucible learned 420 kg of recycled metal, i.e., the total degree of izvlecheny the ri 700oC in a crucible steel download portions at 70-150 kg metallurgical waste from the production of magnesium alloys ("bottom remainders"). During the filling of the crucible (uploaded 1700 kg of waste) the melt was heated to 750oC, was treated with calcium fluoride in the amount of 25 kg (1.35% of the mass of the melt), advocated for 40 min and extracted fused metal - 440 kg. Given that the metal content in the waste about 40%, the degree of extraction of metal from a waste at this amounted to 64.7%. After that, remaining in the crucible, the melt was treated with air at a pressure of 0.15 MPa for 30 min at specific discharge 2.2 cm3/(kgf) and further extracted with 200 kg of recycled metal. The total recovery of metal from waste was 94,1%.Thus, the experimental verification of the proposed method shows that it helps to increase the degree of extraction of metal from scrap and waste up to 90-94%. 1. The method of refining magnesium scrap, including the melting of scrap in the environment of the molten flux certain density with a melt and sedimentation, characterized in that the melt before settling further treated by air under pressure.2. Ways is .1, characterized in that the air supplied under a layer of melt in dispergirovannom.4. The method according to p. 1, characterized in that the specific flow rate of air is maintained within the range of 0.1 to 100.0 cm3/(kg).5. The method according to p. 1, characterized in that the density of the molten flux is kept lower than the density of solid scrap, but higher than the density of secondary molten metal.6. The method according to p. 1, characterized in that the ratio of the mass of molten flux to the mass of processed scrap is maintained within the range of 0.08 to 3.5.7. The method according to p. 1, wherein the melting is carried out at a melt temperature of 700 - 780oC.8. The method according to p. 1, characterized in that the melting lead in a molten flux of the following composition, wt.%: KCl - 45 - 58; NaCl - 8 - 19; MgCl2- 18 - 31; BaCl2- 4 - 12; CaCl2- not more than 2.0; CaF2- not more than 5.0; MgF2- not more than 1.5.9. The method according to p.,1 characterized in that the melt is treated with metallic magnesium in an amount of not more than 3% of its mass.
FIELD: non-iron metallurgy, in particular reprocessing of aluminum waste.
SUBSTANCE: claimed method includes junk charge into premelted flux at ratio of 1:(5-10); heating up to melt temperature; smelting under flux layer, and separation of metal from flux. Equimolar mixture of sodium chloride and potassium chloride with addition of 2.9-52.6 % (in respect to total flux weight) magnesium fluoride is used as flux, and in melting process flux layer with thickness of 4.5-20 cm is maintained. Method affords the ability to conserve original composition and eliminate additional burdening with magnesium.
EFFECT: decreased burn-off loss, especially for magnesium, metal of improved quality.
4 cl, 3 tbl, 5 ex
FIELD: nonferrous metallurgy.
SUBSTANCE: claimed method comprises combining slags using extraction principle with number of extractions n approaching infinity. Depleting agent efficient in presence of reducing agent is selected from materials enriched with pyrite, pyrrotine, calcium sulfide, and calcium sulfate; metal and alloys mainly containing Si, Al, Fe, C, etc. as well as reducing and sulfidizing complexes consisting of sulfides, oxides, and reducing substances (C, Me). Carbonaceous reducers, utilized individually or in mixture, are any known carbonaceous reducers. Degree of metal Me recovery is in accordance with conventional extraction equation.
EFFECT: increased degree of recovery of nickel from slags, reduced consumption of depleting agent, reduced power consumption and loss of sulfur into gas phase.
6 cl, 1 tbl
FIELD: non-iron metallurgy, in particular reprocessing of lead cakes from zinc manufacturing.
SUBSTANCE: claimed method includes heat treatment of lead cake with flux followed by smelting wherein before heat treatment mixture of lead cake, calcium hydroxide, and clinker from lead cake milling is balled to produce pellets. Pellets have fineness preferably of 30-100 mm. Method of present invention affords the ability to increase total coefficient of lead recovery by 3.1 %.
EFFECT: decreased energy consumption and reduced dust content in exhaust gas.
2 cl, 1 tbl
FIELD: noble metal hydrometallurgy.
SUBSTANCE: invention relates to method for acid leaching of platinum method from secondary raw materials, in particular from ceramic support coated with platinum metal film. Target metals are leached with mixture of hydrochloric acid and alkali hypochlorite at mass ratio of OCl-/HCL = 0.22-0.25 and redox potential of 1350-1420 mV.
EFFECT: decreased leaching temperature, reduced cost, improved platinum metal yield.
FIELD: sludge recovery from surface depositions of chemical equipment.
SUBSTANCE: invention relates to method for recovery of sludge containing platinum-group metals from equipment using platinum metal-based catalysts. Method includes treatment with aqueous solution of active chemical agent (e.g. sodium-ammonium-substituted ethylenediaminetetraacetic salts) while controlling pH value and removing sludge retained on treated surface with diluted aqueous solution of mineral salts or mixture thereof. pH value is adjusted at 2-10, preferably at 3-9 by adding of organic acid selected from group containing citric, oxalic, maleic, phthalic, adipic, glutaric, succinic acids or basic agents selected from sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate, and hydrochloric acid, sulfuric acid or phosphoric acid is used as mineral acid.
EFFECT: recovery platinum-group metal with improved yield.
4 cl, 1 tbl, 12 ex
FIELD: rare, dispersed and radioactive metal metallurgy, in particular hydrometallurgy.
SUBSTANCE: invention relates to method for reprocessing of polymetal, multicomponent, thorium-containing radwastes, formed when reprocessing of various mineral, containing rare-earth elements, Nb, Ta, To, V, Zr, Hf, W, U, etc. Method includes treatment of solution and/or slurry with alkaline agent; introducing of sulfate-containing inorganic compound solution and barium chloride; treatment of obtained hydrate-sulfate slurry with iron chloride-containing solution, and separation of radioactive precipitate from solution by filtration. As alkali agent magnesia milk containing 50-200 g/dm2 of MgO is used; treatment is carried out up to pH 8-10; sodium sulfate in amount of 6-9 g Na2SO4/dm2 is introduced as solution of sulfate-containing inorganic compound; barium chloride solution is introduced in slurry in amount of 1.5-3 g BaCl2/dm2. Hydrate-sulfate slurry is treated with solution and/or slurry containing 0.8-16 Fe3+/dm2 (as referred to startingsolution) of iron chloride, followed by treatment with high molecular flocculating agent and holding without agitation for 0.5-2 h. Radioactive precipitate is separated from mother liquor, washed with water in volume ratio of 0.5-2:1; then washed with sodium chloride-containing solution and/or slurry in volume ratio of 0.5-2:1; radioactive precipitate is removed from filter and mixed with mineral oxides in amount of 0.5-0.8 kg MgO to 1 kg of precipitate. Formed pasty composition is fed in forms and/or lingots and presses with simultaneous heating up to 80-1200C.
EFFECT: filtrate with reduced radioactivity due to increased codeposition coefficient of natural Th-232-group radioactive nuclide, in particular Ra-224 and Ra-228, with radioactive precipitates.
10 cl, 1 ex
FIELD: chemical technology; recovery of deactivated and decontaminated radioactive industrial wastes.
SUBSTANCE: proposed method that can be used for deactivating and decontaminating industrial radioactive wastes incorporating Tb-232 and their daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Sl, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like includes dissolution of wastes, treatment of solutions or pulps with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9 - 10 in the amount of 120-150% of total content of metal oxyhydrates stoichiometrically required for precipitation, pulp is filtered, and barium chloride in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp, as well as pre-diluted sulfuric acid spent 5 - 20 times in chlorine compressors in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2 are introduced in filtrate. Alternately introduced in sulfate pulp formed in the process are lime milk to pH = 11 - 12, then acid chloride wash effluents from equipment and industrial flats at pulp-to-effluents ratio of 1 : (2 - 3) to pH = 6.5 - 8.5, and pulp obtained is filtered. Decontaminated solution is discharged to sewerage system and sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization process; then 35 - 45 mass percent of inert filler, 10 - 20 mass percent of magnesium oxide, and 15 -m 25 mass percent of magnesium chloride are introduced in pasty mixture formed in the process while continuously stirring ingredients. Compound obtained is subjected to heat treatment at temperature of 80 - 120 oC and compressed by applying pressure of 60 to 80 at.
EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes due to enhanced coprecipitation of natural radionuclides.
7 c, 1 ex
FIELD: chemical technology; deactivation and decontamination of radioactive industrial products and/or wastes.
SUBSTANCE: proposed method designed for deactivation and decontamination of radioactive industrial products and/or production wastes incorporating Th-232 and its daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Al, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like and that ensures high degree of coprecipitation of natural radionuclides of filtrates, confining of radioactive metals, and their conversion to environmentally safe form (non-dusting water-insoluble solid state) includes dissolution of wastes, their treatment with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9-10 in the amount of 120-150% of that stoichiometrically required for precipitation of total content of metal oxyhydrate; then pulp is filtered and barium chloride is injected in filtrate in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp and pre-dissolved in sulfuric acid of chlorine compressors spent 5-20 times in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2. Then lime milk is added up to pH = 11 - 12 and acid chloride wash effluents of equipment and production floors are alternately introduced in sulfate pulp formed in the process at pulp-to-effluents ratio of 1 : (2-3) to pH = 6.5 - 8.5. Filtrate pulp produced in this way is filtered, decontaminated solution is discharged to sewerage system, sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization, inert filler and 0.5 - 2 parts by weight of calcium sulfate are introduced in pasty mixture while continuously stirring them. Compound obtained in the process is placed in molds, held therein at temperature of 20 - 50 oC for 12 - 36 h, and compacted in blocks whose surfaces are treated with water-repelling material.
EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes.
8 cl, 1 dwg, 1 ex
FIELD: utilization of secondary raw materials containing iron, zinc and lead, mainly wastes of steel-making process at control of basicity of Waelz process slag.
SUBSTANCE: proposed method includes mixing the charge containing raw materials and chemically active fine-grained carbon carrier, agglomeration and treatment of conglomerates thus obtained in furnace. Treatment is performed in rotary furnace working on counter-flow principle of charge and gas atmosphere; in the course of treatment, part of carbon carrier is fed to conglomerates so that total amount of carbon is lesser than 80% of amount of carbon required for reactions in charge; amount of chemically active fine-grained carbon carrier is strictly substoichiometric relative to all reactions in charge requiring carbon.
EFFECT: enhanced balance of energy of Waelz process; increased productivity; improved quality of wastes.
FIELD: production of aluminum by electrolysis of molten salts; processing wastes of this process.
SUBSTANCE: proposed method includes delivery of solid fluorocarbon-containing wastes and oxygen-containing gas into reactor followed by high-temperature roasting for obtaining secondary raw material for production of aluminum. Finely-dispersed fluorocarbon-containing and sulfur-containing wastes are fed for roasting at weight ratio of fluorine to sulfur no less than 4:1; anode gases of electrolytic aluminum production process taken from organized gas cleaning system are used as oxygen-containing gas. Wastes are delivered in form of suspension in which liquid-to-solid ratio is maintained at 0.5-1.5:1. Proposed method improves operation of electric precipitators and ensures return of compounds in form of secondary high-quality regenerating cryolite.
EFFECT: reduced emissions of toxic agents into atmosphere.