Ecological method of complex extraction of nonferrous, rare and precious metals from ores and materials

FIELD: metallurgy.

SUBSTANCE: invention relates to hydrometallurgy. Particularly it relates to method of extraction of nonferrous (Cu, Zn, Co, Ni and others), rare (U, rare earths, Y, Re, Ti, In and others) and precious (Au, Ag, Pt, Pd and others) metals from ores and materials. Method includes leaching of ores in two stages. At the first stage ore and materials treatment is implemented by the first spillage leaching solution with introduction of sulfuric acid and salts of ferric iron in amount, providing in the end of leaching in productive solution molar ratio ion concentration of ferric and ferrous iron no lower than 1:1. At the second stage ore and materials treatment is implemented by the second spillage leaching solution with introduction of sulfuric acid, thiocyanate salts and ferric iron in amount, providing in productive solution molar ratio of ion concentration of thiocyanate and ferric iron no higher than 2:1 and no lower 0.5:1, and ratio of concentration ferric and ferrous iron ions are also no lower than 1:1. Then it is implemented separate processing productive solutions of each stage by means of chemical deposition, sorption and/or electrolysis and spillage solutions return for corresponding stage.

EFFECT: increasing of extraction ratio of nonferrous, rare and precious metals.

5 cl, 5 tbl, 11 ex

 

The invention relates to metallurgy, namely wet methods for extracting non-ferrous (Cu, Zn, Co, Ni and others), rare (U, rare earths, Y, Re, Tl, In, and others) and precious (Au, Ag, Pt, Pd and other) metals from ores and materials, and can be used for agitation leaching and heap, sample, underground and other methods of filtration leaching.

The known method for complex extraction of non-ferrous and precious metals from ores containing sulfides of metals, including the processing of aqueous acid composition in the presence of ferric ions and a material containing manganese, capable of chemical recovery (see U.S. patent No. 4740234, MKI SW 11/04 for 1988). The method involves a two-stage processing of ores. In the first stage, carry out the dissolution of sulfides under the action of the oxidant, ferric ions and mn containing material, such as pyrolusite. In the non-ferrous metals into solution, and precious metals are released for subsequent leaching in the second stage cyanidation.

The ratio of ion concentrations three - and ferrous iron in productive solutions in the first stage leach is not regulated. This may result in reduced recovery of non-ferrous metals in the first stage, and if in the second stage to apply Vyselki is of salts rodando (thiocyanates) and trivalent iron, it may decrease the degree of extraction of precious metals. Cyanide from an environmental point of view is very harmful and dangerous process.

Known also integrated two-stage extraction of non-ferrous, rare and precious metals from ores and concentrates containing sulfide sulfur, using bacterial leaching (see the book Chipolina, Avedisova, Van "Technology of bacterial leaching of non-ferrous and rare metals". M.: Nedra, 1982). In the first stage leached non-ferrous and rare metals sulfate solutions in the presence of oxygen, ions of divalent or trivalent iron, and bacteria Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans, and in the second stage, cyanidation to extract precious metals.

The ratio of ion concentrations three - and ferrous iron in productive solutions in the first stage leach is not regulated. As a result, may reduce the degree of extraction of non-ferrous metals in the first stage and precious metals in the second stage. Cyanide degrades the ecological purity of the process.

Closest to the proposed invention in terms of leaching of precious metals in the second stage is a method comprising leaching gold and silver from ores solutions rodando (t is iyanatul) in the presence of oxidants, including ferric (see "Thermoschemistry of thiocyanate systems for leaching gold and silver ores" O. Barbosa, Montemius A., Precions Metals, 89: Proc. Jnt. Symp. TMS Ann. Mut, Las Vegas. Nov. Febr. 27 - March.2, 1989. - Warrendale (Pa), 1989). The method is recommended for the most efficient leaching of gold to maintain in solution the pH value of 1-3, the concentration of thiocyanate ions 0.5 to 0.01 m and the redox potential of 600-700 mV; leaching of silver required potential at 100 mV below. The ratio in solution concentrations of thiocyanate ions and trivalent iron and trivalent ions and ferrous iron is not regulated.

In the recommended conditions depending on the ratio in solution concentrations of thiocyanate ions and trivalent iron and trivalent ions and ferrous iron may decrease the degree of extraction of precious metals.

The objective of the invention is to increase the degree of extraction of non-ferrous and rare metals in the first stage and precious and rare metals in the second stage, as well as improving the environmental cleanliness of the whole process.

This object is achieved in that the introduction in the leaching solution of sulfuric acid and salts of trivalent iron in the first stage support in an amount to provide at the end of leaching in a productive solution the molar ratio of the ion concentration is in the trivalent and divalent iron not less than 1:1, and in the second stage, the introduction of sulfuric acid, salts of rodando and trivalent iron in the leaching solution support in an amount to provide in a productive solution the molar ratio of ion concentrations of thiocyanate and ferric not exceeding 2:1 and not less than 0.5:1, and the ratio of the concentrations of ions of trivalent and divalent iron is also not lower than 1:1.

The invention consists in the determination of the optimal molar ratio of the concentrations of ions of trivalent and divalent iron, as well as concentrations of thiocyanate ions and trivalent iron in which the leaching process proceeds with a large extraction of non-ferrous metals in the first stage and precious metals in the second stage.

In ores containing sulfide sulfur, non-ferrous, rare and precious metals, valuable components or form a chemical compound with a sulfide sulfur (nonferrous metals)or associated with sulphides, which block the access of the used solvent (precious and rare metals), or sulfides reduce the redox potential of the leach solution below the level required for the dissolution of metals. Typically, conditions and solvents for leaching of non-ferrous and precious metals differ significantly. In addition, the collective processing of products is active solutions of these metals is significantly complicated. So they used the two-stage leaching. The first stage is carried out, the maximum production of sulphides, which is provided by removing the solution of non-ferrous and rare metals, releasing precious and rare metals and capacity building of leach solution.

So in the leaching of ores containing sulfide sulfur, with the introduction of sulfuric acid and ferric salts interaction, for example, with pyrite as the most common sulfide mineral, flows through the reaction:

The standard redox potential of Fe3+/Fe2+, Eh0Fe=0,771 Century, the Potential dissolution of pyrite is equal to 0.53 Century Real potential pairs of Fe3+/Fe2+is calculated by the equation:

where n is the number of electrons, and is the equilibrium molar concentrations of the respective ions. From equation (2) implies that the potential of the pair of iron depends on the ratio of ion concentrations three - and ferrous iron in solution. If this ratio is below 1:1, the potential of the system iron becomes lower than the standard, i.e. below 0,771 In, and close in magnitude to the potential of the sulfide mineral. The process of producing sulphides slows down and eventually the production of sulfides is reduced. the on the contrary, than the ratio above 1:1, the higher the production of sulfides. The higher the degree of extraction of non-ferrous metals in the first stage, and precious metals - in the second stage. The real potentials of most sulfide minerals in the acidic environment, such as pyrite, sphalerite, chalcopyrite, arsenopyrite, covelin, chalcocite, vary mainly in the range of 0.2-0.6 In, reaching in the case of chalcopyrite 0,768 In, that is almost the standard potential of the system iron (see the book Chipolina, Avedisova, Van "Technology of bacterial leaching of non-ferrous and rare metals". M.: Nedra, 1982). But if we turn to the equation of the real potential of iron (2), we see that its value is equal to 0,771 In case the ratio of the molar concentrations of the ions three - and ferrous iron in the solution is 1:1. In other words, the ratio of the ions can be considered as the boundary at which the generation of sulphides minimum. If, for example, to the production of sulfide sulfur in the first stage agitation flow or seepage leaching, maintaining the ratio of ion concentrations three - and ferrous iron in the leach solution is greater than 1:1, in the course of the process in a productive solution, this ratio may be below the value of 1:1. But as the production of sulfides, it will increase and at the end of the process will also be above 1:1 and uproductive solution, that would indicate the maximum possible generation of sulfides. To maintain this ratio is possible as a direct introduction to the solution of salts of trivalent iron and the oxidation of the bivalent iron ions, using the processing of ore and/or solution by the addition of oxidant: air, oxygen, pyrolusite, and others, including the use of bacteria Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans. If the ore contains ferric minerals, this correlation can be supported by the additional introduction of a solution of sulfuric acid, dissolving these minerals.

The ore may contain other ferric reducing agents, for example arsenic, as well as the minerals ferrous or non-ferrous and rare metals in restored form, for example uranium as UO2. In each of these cases in the circulating solution will accumulate ions of bivalent iron and its correlation with trivalent iron will affect the degree of extraction of non-ferrous and rare metals in the first stage and precious metals (as will be shown below) in the second stage.

Thus, if at the first stage, the introduction of sulfuric acid and ferric iron in the leach solution to support in an amount to provide in the pregnant solution at the end of the leaching molar ratio of concentration of the ions of trivalent and divalent th iron not less than 1:1, extraction of non-ferrous metals in the first stage and subsequent extraction of precious metals in the second stage will be higher.

It should also be noted that the molar ratio of the concentrations of ions of trivalent and divalent iron not less than 1:1 in the pregnant solution at the end of leaching in the first stage will serve as the guarantee that this ratio will at least persist and in the second stage and, as will be shown below, will increase the extraction of precious metals.

The invention in part leaching of precious metals is to determine the optimal molar ratio of the concentrations of ions of trivalent and divalent iron, as well as concentrations of thiocyanate ions and trivalent iron in which the leaching process proceeds with a large extraction of precious metals.

Leaching, for example, gold solution containing thiocyanate ions and trivalent iron, flows through the reaction:

The standard redox potential of the system Au/Au(SCN)4-the dissolution of gold, Eh0Au= 0,655 (see Handbook of electrochemistry. / Edited by A. M. Sukhotin. - L.: Chemistry, 1981). The standard potential of the system Fe3+/Fe2+, Eh0Fe=0,771 C. Thus, the potential difference jelly is a and gold shows what is thermodynamic probability of the process of dissolution of gold in standard conditions is quite high. The real potential of these systems according to the Nernst formula will be:

where n is the number of electrons, andAuis the equilibrium molar concentration (activity) rhodanate complex gold and equilibrium concentrations of the respective ions.

This shows that the system's potential gold depends on the ratio of equilibrium concentrations rhodanate, gold and thiocyanate ion in solution, and the system capacity of iron is associated with the ratio of the equilibrium concentrations of the three - and ferrous iron.

Electromotive force (EMF) of the process is equal to the difference of potentials of iron and gold and is calculated by the formula:

But when the equilibrium of reaction (3) EhFe- EhAu=0. Then, transforming the expression (6), we obtain:

or

Substituting the values of the standard potentials in the left part of equation (7) we obtain:

If you pay attention to the reaction (3), we can see that the expression under the sign of the logarithm in equation (7) is an expression of the equilibrium constant for this reaction, that is,

where

The value of the equilibrium constant shows that when equilibrium under standard conditions the product of the equilibrium concentrations of the products of the reaction (3) will be a million times more than the product of the concentrations of the starting materials. Or direction of the reaction almost completely shifted towards the dissolution of gold.

However, it is known that ferric ions form ions with thiocyanate a number of complex compounds with corresponding constants instability (see the book Yu "Handbook of analytical chemistry M.: Chemistry, 1971): Fe(SCN)2+with K1=10-3; Fe (SCN)2+with K1,2=10-4,33; Fe (SCN)3with K1,2,3=10-4,63that are able to bind ions such as thiocyanate and iron, changing the equilibrium of reaction (3), and hence its direction. Comparing the values of the constants instability can be seen that the most durable is the complex of Fe(SCN)2+with K1=10-3that mainly determines the equilibrium in the system and dissociates according to the reaction:

The constant expression instability for reaction (9) will be:

where atois the equilibrium molar concentration of iron-rhodanate complex. Transforming the expression (10) in equation aFe3+·aSCN=andto·10-3and the treatment tip can the Aviv expression product of concentrations of iron ions and thiocyanate in equation (8) we obtain:

From comparison of the expressions of the constants instability rhodanate complex of iron (10) and the equilibrium constant for the reaction of dissolution of gold (11) shows that, on the one hand, the negative degree values of the latter indicates the shift of the equilibrium in the opposite direction, i.e. in the direction of gold deposition. It was concluded that the process of dissolution of gold in the presence of thiocyanate ions and iron reversible. On the other hand, the direction of the reaction depends on the equilibrium concentrations of bivalent iron ions, thiocyanate and rhodanate complex of trivalent iron concentration which, in turn, depends on the concentration of ferric ions and thiocyanate.

If from equation (11) to Express the equilibrium concentration of gold, the expression will have the form:

Thus, maintaining a certain concentration of the respective ions in solution, it is possible to control the leaching process. However, the equilibrium concentration of thiocyanate and complex in solution analytically is not possible to determine due to the presence of the rolling dynamic equilibrium and the relative instability of iron-rhodanate complex. This does not apply to ferrous iron ion, which does not form complexes and its equilibrium concentration equal the total concentration. Therefore, it is necessary equilibrium ion concentration be expressed through the total concentration that can be determined analytically. Again back to the reaction of dissociation of iron-rhodanate complex (9):

Whence it follows that for a simple binary compounds of this complex dissociate one mole of iron and one mol of thiocyanate, the total molar concentration (C) iron ions and thiocyanate will be equal to the sum of the equilibrium concentrations of the complex and the corresponding ion, namely:

Hence Express equilibrium concentration of the complex through the total ion concentration:

Next we Express the equilibrium concentration of iron ions and thiocyanate through total concentration. So, from the expressions (14) it follows that

Now, if the expression (14, 15) for atoand aSCNsubstitute in equation (12), we get an equation of the dependence of the equilibrium concentration of gold in solution from the total ion concentration of the two-, trivalent iron and thiocyanate:

From the expression (16) shows that the equilibrium concentration of gold depends not only on the total concentration of ions of two -, trivalent iron and thiocyanate, but also on the ratio between the two. In connection with the foregoing essence of the present invention is the determination of the optimal molar ratio of total ion concentrations of thiocyanate and ferric (CSCN:CFe3+), as well as ions of trivalent and divalent iron (CFe3+:CFe2+), in which the equilibrium gold concentration maximum, and therefore, the probability of the process of leaching with a large gold recovery increases.

To determine the optimal ratios will carry out an approximate calculation of equilibrium concentrations of gold for various ratios of total concentrations CSCN:CFe3+from 0.5:1 to 2:1. (Approximate calculation, so as to simplify the calculation, it was not taken into account ionic strength of the solution and the activity coefficients of the ions). To do this, take two options total concentrations of thiocyanate ion, as recommended in the above analog: 1·10-2m and 0.5 m And the concentration of thiocyanate is assumed constant over the entire range of ratios, and the concentration of trivalent iron is variable. To simplify the calculation, we will take a constant and molar concentration of ferrous iron, which can in practice to support using any additional oxidant (oxygen, air, pyrolusite and other).

Here is an example calculation for a single ratio of CSCN: Fe3+=0,5:1, for others it will be similar. The total concentration of thiocyanate is assumed to be 1·10-2m, the total concentration of divalent iron is ten times less, or 1·10-3m For the ratio of 0.5:1, the total concentration of ions of trivalent iron is 2·10-2M. Further, if the constant expression instability of the complex (10) to substitute the values of the equilibrium concentrations of the ions from expressions (14, 15)you will get:

Denoting aSCNthrough x and substituting the adopted values of the total concentration of ions in the expression (17) we get the equation:

Solving equation (18) by the method of successive approximations, we find that x=0,84·10-3or aSCN=0,84·10-3. Then ato=CSCN-aSCN=1·10-2-0,84·10-3=9,16·10-3. Hence, the equilibrium concentration of gold by the formula (16) will be equal to:

Examples 1-10.

In table 1 examples of calculated indices ionic equilibrium in solution for various ratios of total ion concentrations CSCN:CFe3+from 0.5:1 to 2:1. Examples 1-4 for the total concentration of thiocyanate 1·10-2m and examples 5-8 for the total concentration of thiocyanate 0.5 m

As follows from table 1 that with the increase in the ratio CSCN:CFe3+from 0.5:1 to 2:1 equilibrium concentration of gold in the learn the total concentration of thiocyanate 1·10 -2m varies from up to 0.127 0,087 g/l, passing through a maximum in 0,207 g/l with a ratio of CSCN:CFe3+=1:1. If the total concentration of thiocyanate 0.5 m, similarly, the equilibrium concentration of gold, varying from 0,197 to 6.1 g/l, passes through a maximum in 9,65 g/l, but when the ratio of CSCN:CFe3+=1,5:1. In our opinion, such behavior of the gold is associated with the degree of dissociation rhodanate complex of iron, which in dilute solutions increases, and in concentrated decreases. The degree of dissociation of weak electrolytes is calculated as the ratio of the equilibrium concentration of the ion being in disadvantage to the total concentration of this ion (see the book B.P. Nadey "Theoretical justifications and calculations in analytical chemistry", M: "High school", 1959). The data in the table show that the degree of dissociation of the complex also passes through a maximum, which corresponds to the ratio of thiocyanate ions and trivalent iron 1:1. But in the case of dilute solutions this maximum is 27%, and in concentrated solutions is only 4.4%. Moreover, if in dilute solutions of thiocyanate highs equilibrium concentration of gold and the degree of dissociation of the same when the ratio of CSCN:CFe3+=1:1, in concentrated solutions the maximum gold is observed at a higher ratio of CSCN:C Fe3+=1,5:1 and less dissociation of the complex to 0.6%. This is because the equilibrium concentration of gold, calculated by the formula (12), depends on the compositions of the equilibrium concentrations of thiocyanate ions and complex. But, if you look at the change in concentration of the complex with the increase in the ratio CSCN:CFe3+the concentration of the complex in dilute and concentrated solutions of thiocyanate is reduced to about half. Equilibrium concentration of thiocyanate in dilute solutions is increased only 6.8 times, and concentrated in 250 times. That is crucial in increasing the equilibrium concentration of gold or works and3to·aSCNin the formula (12) in dilute solutions have a concentration of the complex, and concentrated in the concentration of thiocyanate. In other words, in dilute solutions of thiocyanate max gold will approach the ratio of CSCN- CFe3+=0,5:1, and concentrated to the value CSCN:CFe3+=2:1. You can actually calculate that reducing the total concentration of CSCNup to 1·10-3m maximum concentration of gold will correspond to the value CSCN:CFe3+=0,5:1, while increasing the total concentration of CSCNup to 1 m maximum concentration of gold will correspond to the value CSCN:CFe+ =2:1. The concentration of CSCN=1·10-3m or 58 mg/l can be considered as the minimum limit for practical use in the processing, for example, ores by heap leaching, and Vice versa, the concentration of CSCN=1 m or 58 g/l can be considered as the maximum limit for the processing of concentrates and other rich gold materials. From this we conclude that the interval ratios of CSCN:CFe3+from 0.5:1 to 2:1 can be considered optimal. That is, if the leaching of ores and materials to support productive solutions the ratio of CSCN:CFe3+not lower than 0.5:1 and above 2:1, then ceteris paribus the concentration of gold and its extraction will be higher.

Relative to the ratio in the solution is CFe3+:CFe2+from the data in table 1 shows that with the increase in the ratio CSCN:CFe3+from 0.5:1 to 2:1 ratio of CFe3+:CFe2+decreases in dilute and concentrated solutions, equally from 20:1 to 5:1. While the minimum ratio of 5:1 in dilute solutions corresponds to the concentration of gold 0,087 g/L. If you reduce this ratio to 1:1, for example, by increasing the concentration of ferrous iron in five times the concentration of gold in accordance with formula (16) will be reduced to 125 times and will be 0.7 mg/l In more dilute solutions it b the children even lower. But such a concentration of gold, as is known from the practice of processing ore by heap leaching, it is possible to take the minimum limit for industrial use. Similarly, when the transition to concentrated solutions of value CFe3+:CFe2+=1:1 will match the gold concentration of about 50 mg/l, which you can also take the minimum limit for industrial processing of concentrates. Therefore, the ratio of CFe3+:CFe2+=1:1, in our opinion, you can take the minimum limit. Thus, if the leaching of ores and materials to support productive solutions the ratio of CSCN:CFe3+not lower than 0.5:1 and above 2:1, and the ratio of CFe3+:CFe2+not below 1:1 - that ceteris paribus the concentration of gold and its extraction will be higher. Although the calculation is approximate, from equation (16) implies that the introduction in the calculation of the activity coefficients of the ions can only change the absolute values of the concentrations of gold, but the pattern passing through the maximum will be saved.

Of course, that the change in the proportion of thiocyanate ions, three - and ferrous iron will have an impact on the value of the redox potential in the solution and not simply to maintain the value of the building at a certain level? In our opinion, it would be better still to maintain aspect] is the determination of ion concentrations, because due to the complex material composition of ores and materials, the magnitude of the potential will not be fully reflective of the concentration ratio of only these ions and every time this optimum potential, you need to determine empirically. The ratio of ion concentration can easily be determined analytically and apply to any ores and concentrates. To demonstrate this, let us calculate the real potentials in the range of the ratio of equilibrium concentrations of ions three - and ferrous iron, are shown in table 1, relative to silver chloride reference electrode, most often used in practice. The calculation will spend it on ions of iron, as in our system, they are only potential-determing because both oxidized and reduced their form is in solution. Calculation of conduct by the formula:

where EhAgCl=0,V - potential silver chloride reference electrode in saturated KCl solution at 25°C. the calculation Results are shown in table 1. As follows from table 1, in dilute solutions with the increase in the ratio of the concentrations of thiocyanate ions and trivalent iron and the reduction ratio of the concentrations of ions three - and divalent iron potential of the solution decreases from 608 to 541 mV, and in concentrated solutions from 608 to 49 mV. If this data is compared with the interval of potentials in the 600-700 mV recommended in the above analogy, we can see that in our case the interval of optimal potentials much lower.

Relative to other precious metals such as silver and platinum group metals can say that they all have a redox potential significantly lower than the potential of gold, and at the same time, all form a solid rhodanate complexes. Therefore, in our opinion, all other precious metals also with a large extraction will vydeliajutsia the above optimum range of ratios of ion concentrations of thiocyanate, three - and ferrous iron.

It should be also noted that the ratio of ions CSCN:CFe3+not lower than 0.5:1 and above 2:1, and the ratio of CFe3+:CFe2+not less than 1:1, you need to keep it in productive solutions. In leach solutions of these relations may go beyond the given boundary values. If, for example, to the processing in the second stage agitation flow or seepage leaching, maintaining the ratio of CFe3+:CFe2+in the leaching solution is significantly greater than 1:1, and the ratio of CSCN:CFe3+significantly below 0.5:1, in the course of the process in a productive solution, this ratio is due to shimodate with residual sulfide sulfur (or other reducing agents) and restore parts of the trivalent iron may vary. All in all, a productive (output) the solutions of these ratios were within the indicated limits. To maintain these ratios are possible as a direct introduction to the leaching solution of salts of thiocyanate and ferric iron and the oxidation of the bivalent iron ions in it, using the processing of ore and/or solution by the addition of oxidant: air, oxygen, pyrolusite, and others, including the use of bacteria Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans. If the ore contains ferric minerals, this ratio can be maintained more introduction in the leaching solution of sulfuric acid, dissolving these minerals.

Relatively rare metals can say the following. Some of them, such as uranium, rare earth, cadmium, rhenium, etc. can vydeliajutsia as along with non-ferrous metals, and independently of the first stage solutions of sulfuric acid in the presence of ferric ions. Another part, such as thallium, indium, mercury, and others, are capable of forming rhodanate complexes, can be extracted along with precious metals in the second stage.

In respect of ecological purity process replacement cyanidation rhodanate leaching of precious metals significantly improves environmental safety and cleanliness of the way as Rodney not reveal who I highly toxic substances and significantly less harmful to the environment.

Thus, if at the first stage, the introduction of sulfuric acid, and salts of trivalent iron in the leaching solution is maintained in an amount to provide in the pregnant solution at the end of leaching the molar ratio of the concentrations of ions of trivalent and divalent iron not less than 1:1, and the second stage introduction of sulfuric acid, salts of rodando ferric support in an amount to provide in a productive solution the molar ratio of ion concentrations of thiocyanate and ferric not exceeding 2:1 and not less than 0.5:1, and the ratio of ions of trivalent and divalent iron is also not lower than 1:1, extraction of non-ferrous and rare metals in the first stage and subsequent extraction of precious and rare metals in the second stage will be higher and the problem should be resolved.

The proposed method in the laboratory conducted a two-stage leaching of crushed ore containing: Fe2About3- 70%of the sulfide sulfur is 0.7%, Cu of 0.5%, Zn - 0.7% and Au - 4.8 g/tons of ore Sample in each of the three experiments was 1 kg Leaching was carried out in polyethylene vessels under stirring by a mechanical stirrer respect to W:T=2:1 and a temperature of 20°C. the Minerals copper and zinc were represented mainly chalcopyrite and sphalerite, iron - hematite. In the first stage wimalasiri the spent sulfuric acid solution, introduction over three experiments were supported in the same number. Periodically, the stirring was stopped and the solution was analyzed on the content of three - and ferrous iron. After that, the slurry was injected 85% pyrolusite in the estimated amount to provide a molar ratio of ion concentrations three - and ferrous iron, in the experience of 1-2:1, in experiment 2-1:1, in the experience of 3-0,5:1. The leaching was continued for 24 hours. Then the pulp of all three experiments was filtered, the cake washed with water and the solution was determined by the content of zinc and copper, which were calculated the degree of extraction of these metals. The results are presented in table 2.

Table 2
The results of the first stage leach
Indicators of a productive solutionEd. MEAs.Experience, №
123
The ion concentration of Fe3+g/l
m
2,2
4·10-2
1,6
2,9·10-2
1,0
1,8·10-2
The ion concentration of Fe2+ g/l
m
1,1
2·10-2
1,5
2,7·10-2
2,3
4,1·10-2
The molar ratio
CFe3+·CFe2+
-a 2.0: 11,1:1of 0.44:1
The concentration of Zng/l3,052,84to 1.86
The concentration of Cu-"-to 2.061,981,22
The degree of extraction of Zn%of 87.081,153,2
The degree of extraction of Cu-"-82,379,149,0

As can be seen from table 2, in maintaining productive solution ratio of concentrations of ions of trivalent and divalent iron from 1.1:1 to 2.0:1 in experiments 1, 2, that is, not lower than 1:1, resulted in the extraction of zinc and copper 81,1-87,0% and 79.1-82,3%, respectively. The decline of this ratio in experiment 3 to ,44:1 significantly reduced the extraction of these metals 49.0-53,2%.

Next, the washed cake ore from experiment 1 (see table 2) was divided into 5 equal parts and rasulpur in each of the five subsequent experiments (see table 3, experiments 4-8) water with respect to W:T=2:1, the same amount of ore was taken from the experience of 3 and also rasulovna (experiment 9). We then conducted leaching with stirring and introduction of sulfuric acid and sodium thiocyanate. The concentration of thiocyanate ion was maintained in all experiments, equal in the number of 0.58 g/l or 1·10-2m, and sulfuric acid were injected quantity. Periodically, the stirring was stopped and the solution analyzed the content of thiocyanate ions, three - and ferrous iron. After that, the slurry was injected sulfuric acid in the estimated amount to provide a molar ratio of ion concentrations of thiocyanate and ferric in experiments 4-8 from 0.3:1 to 3:1, and in the experience 9-1:1. The molar ratio of three - and ferrous iron only was recorded. The leaching was continued for 24 hours. Then the pulp of all six experiments was filtered, the cake washed with water and the solution was determined by the gold content, which was calculated the degree of extraction. The results are presented in table 3.

Table 3
The results of the second leaching stage
Indicators of a productive solutionEd. MEAs.Experience, №
456789
The concentration of the ion SCN-g/l m0,58
1·10-2
0,58
1·10-2
0,58
1·10-2
0,58
1·10-2
0,58
1·10-2
0,58
1·10-2
The ion concentration of Fe3+g/l m1,70
3·10-2
1,15
2·10-2
0,57
1·10-2
0,28
5·10-2
0,18
3,2·10-3
0,56
1·10-2
The molar ratio
CSCN-:CFe3+
-of 0.33:1of 0.5:11:12:13:11:1
The ion concentration of Fe2+g/l m0,12
2,1·103
0,12
2,1·10-3
0,12
2,1·10-3
0,12
2,1·10-3
0,12
2,1·10-3
1,1
2·10-2
The molar ratio of CFe3+:CFe2+-15:110:15:12,5:1the 1.5:1of 0.5:1
The concentration of Aumg/l1,121,802,021,721,240,25
The degree of extraction Au%46,775,084,171,651,621,0

As follows from the data of table 3, maintaining the molar ratio of the concentrations CSCN-:CFe3+in experiments 5-7 from 0.5:1 to 2:1, provided the extraction of gold in the amount of 1.6 - 84,1%, and the molar ratio of CFe3+:CFe2+was from 2.5:1 to 10:1, i.e. greater than 1:1. When the decrease in the ratio of CSCN-:CFe3+to 0.33:1 in experiment 4 the extraction of gold is sharply reduced to 46.7%, despite the value OfFe3+:CFe2+=15:1. Similarly, when the magnification ratio CSCN-:CFe3+to 3:1 in experiment 8 the extraction of gold also sharply reduced to 51.6 per cent, while the ratio of CFe3+:CFe2+=1,5:1 remains above 1:1. The decrease in the ratio of CFe3+:CFe2+in the experience of 9 to 0.5:1, i.e. below 1:1 resulted in a further decrease in the extraction of gold - to 21.0%, although the ratio of CSCN-:CFe3+=1:1 is optimal interval.

Thus, the results of the experiments show that the maintenance of the first stage leaching in a productive solution molar ratio of the concentrations of ions of trivalent and divalent iron not less than 1:1, and the second stage is the molar ratio of ion concentrations of thiocyanate and ferric not exceeding 2:1 and not less than 0.5:1, and the ratio of the concentrations of ions of trivalent and divalent iron is also not lower than 1:1 significantly increases the degree of extraction of non-ferrous and precious metals.

As follows from the data of table 4, 5, subject to the required ratios of the ions in the solution during leaching of non-ferrous metals and gold as water, and oronym solutions is virtually identical extraction of metals.

Example 11 (using leaching working solutions)

Obtained in the first stage in experiment 2 (see table 2) productive solution of non-ferrous metals in the 2.0 liter of the composition, g/l: Fe3+- 1,6; Fe2+- 1,5; Cu - 1,98; Zn - 2,84, was processed according to the following scheme. Initially, he was treated with calcium carbonate to bring the pH of the pulp to 4.3 with simultaneous bubbling compressed air for oxidation of Fe2+). The resulting slurry of hydrates of iron and gypsum was filtered and the precipitate washed on the filter with water in an amount necessary to bring the total volume of the filtrate to 2.0 liters purified from iron solution of copper and zinc was treated with caustic soda to bring the pH to 7.0. This suspension was filtered, and the residue of the bulk concentrate of copper and zinc washed with water to obtain 2.0 l stock solution of sodium sulfate composition, g/l: Fe3+- OTS.; Fe2+- OTS.; Cu - 0,005; Zn - 0,05; Na2SO4it is 11.0. Obtained working solution was again used for leaching fresh portions of the ore in 1 kg according to the method described for the experiment 2, where for the preparation of sulfuric acid was used tap water. The results of leaching on clean water and circulating the solution is summarized in table 4.

Obtained in the second stage, the pregnant solution is gold in experiment 6 (see table 3) in a volume of 0.4 l is the composition, g/l: SCN-- 0,58; Fe3+- 0,57; Fe2+- 0,12; Au - 2,02 mg/l, was treated ion exchange resin grade-510 firm Pluralist, pre-charged in SCN-- to reduce the gold content in the mother liquor sorption of less than 0.02 mg/L. After separation of the sorbent mother solution had the composition, g/l: SCN-- 0,59; Fe3+- 0,50; Fe2+- 0,10; Au - 0.02 mg/L.

From the cake from the leaching of ore circulating leach solution in the first stage, we selected a sample of 200 g (dry), which was Rasulova in working mother solution from leaching in experiment 6. It was further held leaching according to the method described for the experiment 6, where for the preparation of leach solution was used tap water.

Table 4
The results of the first stage leaching water and the circulating solution
Indicators of a productive solutionEd. MEAs.Experience, №
22-1
Leaching solution-waterworking capital
The ion concentration of Fe3+g/l
m
1,6
2,9·10-2
1,4
2,5·10-2
The ion concentration of Fe2+g/l
m
1,5
2,7·10-2
1,4
2,5·10-2
The molar ratio
CFe3+:CFe2+
-1,1:11:1
The concentration of Zng/l2,842,90
The concentration of Cu-"-1,981,96
The degree of extraction of Zn%81,181,4
The degree of extraction of Cu-"-79,178,4

Table 5
The results of the second stage leaching water and the circulating solution
Ed. MEAs.Experience, №
66-1
Leaching solution-waterworking capital
The concentration of the ion SCN-g/l
m
0,58
1·10-2
0,59
1·10-2
The ion concentration of Fe3+g/l
m
0,57
1·10-2
0,60
1,1·10-2
The molar ratio
CSCN-:CFe3+
-1:11:1
The ion concentration of Fe2+g/l
m
0,12
2,1·10-3
0,12
2,1·10-3
The molar ratio
WithFe3+:CFe2+
-5:15:1
The concentration of Aumg/l 2,022,05
The degree of extraction Au%84,184,2

1. How complex extraction of non-ferrous, rare and precious metals from ores, including the leaching of ores in two stages: the first stage is the reverse leach solution with the introduction of sulfuric acid, salts of trivalent iron and obtaining productive solutions of non-ferrous and rare metals, in the second stage - the reverse leach solution with obtaining productive solutions of precious and/or rare metals, processing of productive solutions each stage chemical precipitation, adsorption and/or electrolysis, and the return of the circulating solutions of the corresponding stage, characterized in that the second stage of lead leaching working leaching solution with the introduction of sulfuric acid, salts rodando (thiocyanates) and trivalent iron in the first stage, the introduction of sulfuric acid and ferric iron in the leach solution support in an amount to provide at the end of leaching in a productive solution the molar ratio of the concentrations of ions of trivalent and divalent iron not less than 1:1, and in the second stage, the introduction of sulphuric acid Sol is th rodando and trivalent iron in the leaching solution support in the amount providing productive solution the molar ratio of ion concentrations of thiocyanate and ferric not exceeding 2:1 and not less than 0.5:1, and the molar ratio of the concentrations of ions of trivalent and divalent iron not less than 1:1.

2. The method according to claim 1, characterized in that in the first stage at the end of the leaching maintain the molar ratio of the concentrations of ions of trivalent and divalent iron in the pregnant solution is not lower than 1:1 by adding in the leach solution and/or ore oxidant, for example air or oxygen.

3. The method according to claim 2, characterized in that in the first stage, along with air or oxygen in the leach solution add bacteria Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans.

4. The method according to claim 1, characterized in that in the second stage support in a productive solution the molar ratio of ion concentrations of thiocyanate and ferric not exceeding 2:1 and not less than 0.5:1, and ions of trivalent and divalent iron not less than 1:1 by adding in the leach solution and/or ore oxidant, for example air or oxygen.

5. The method according to claim 4, characterized in that in the second stage, along with air or oxygen in the leach solution add bacteria Thiobacillus ferrooxidans and/or Thiobacillus thiooxidans.



 

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4 cl, 6 tbl, 6 ex

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EFFECT: reduction of expenditure of energy and material cost and increasing of receiving materials extraction.

1 dwg, 1 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: group of inventions concerns composition and method for metal extraction from solution. Composition contains one or more orthohydroxiarilaldoximes and one or more orthohydroxiarilketoximes, and also one or more equilibrium modifier in quantity providing modification extent of presented orthohydroxiarilaldoximes from preliminary 0.2 till 0.61. Equilibrium modifiers correspond alkylphenols, alcohols, esters, alkyl oxides and polyether, carbonate, ketones, nitriles, amides, carbamates, sulfoxides, or amine salts and quaternary ammonium compound. At that one or more equilibrium modifier are chosen from group 2,2,4-trimethyl-1,3-pentanediolmonoisobutyrate, 2,2,4- trimethyl-1,3-pentanedioldibenzoate, dibutyladipate, dipenthyladipate, dyhexyladipate, isobutylheptylketone, nonanon, 2,6,8-trimethyl -4-nonanon, diundecylketone, 5,8-diethyldodecane-6,7-dion, tridecanol and nonyl phenol.

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11 cl

FIELD: metallurgy.

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EFFECT: reduction of extractant consumption, increasing of copper extraction selectivity, increasing of cathode copper quality.

8 cl, 2 ex

FIELD: metallurgy.

SUBSTANCE: invention concerns copper hydrometallurgy. Particularly it concerns method for copper extraction received, for instance, ore leaching by means of dense, subterranean and vat method and also from concentrates, dumps, sledges, slugs etc. Method for copper extraction from sulfuric solutions includes extraction at blending of sulfuric solutions with solution of cation-exchange organic selective extractant and further separation of mixture by means of sedimentation with receiving of copper-bearing extract and extraction raffinate. Copper re-extraction from extract is implemented by means of blending extract with solution of sulfuric acid cwith further separation with receiving of copper-bearing extract extractant solution. Then it is implemented cleaning of re-extract by flotation with further filtration or coalescing and electro extraction of copper from clean re-extract with receiving of cathode copper and spent electrolyte. Spent electrolyte is used for copper re-extraction.

EFFECT: decreasing of sulfuric acid consumption, increasing of copper extraction, decreasing of copper losses with spent solutions, improving of cathode copper.

11 cl, 2 ex

FIELD: metallurgy.

SUBSTANCE: invention concerns hydrometallurgical manufacturing and can be used at bioleaching of sulphide products, containing various nonferrous and precious metals. Method of sulphide-bearing ore treatment includes ore leaching stacked on the watertight basis, located at slope, in heap has a form of rustum of pyramid. Leaching is implemented by means of sulfuric acid solution at concentration 2-10 g/l, containing ions of ferric iron by concentration 1-20 g/l, iron-oxidizing bacteria with microelements and sulphur-oxidizing bacteria. After collection of flowing out solution it is implemented iron regeneration in collected solution in separate instrument by immobilized on neutral bearer bacteria with aeration by air. Metals extraction is implemented from leaching solution.

EFFECT: increasing of metals extraction ratio, decreasing of treatment time.

4 cl, 2 ex

FIELD: metallurgy.

SUBSTANCE: method includes mixing of source concentrate with calcium oxide CaO and calcium peroxide CaO2 and burning in two stages. At the first stage burning is carried out at temperature of 350-500°C within 30-40 minutes, at the second stage - at temperature of 500-800°C during 30-60 minutes. After burning there is performed leaching of non-ferrous metals out of cinder. Consumption of calcium oxide CaO is 50-100% from stoichometric required for binding sulphur into gypsum while consumption of calcium peroxide CaO2 is 1-10% from concentrate weight.

EFFECT: increased extraction of non-ferrous metals and reduced duration of cinder leaching.

2 cl, 2 tbl, 2 ex

FIELD: metallurgy.

SUBSTANCE: invention is related to noble metals metallurgy and can be used for technology of desilverisation and gold extraction from zinc-bearing golden-silver cyanic sediments with increased content of silver. Initial zinc-bearing golden-silver cyanic sediment is leached, at first, in nitric acid solution and then into received pulp excluding filtration it is added caustic soda solution till achieving the concentration NaOH, equal to 100-140 g/l. After it alkaline solution is separated from non-solved sediment. The latter is washed by alkaline solution, dried, molten with fluxes on golden-silver alloy. Received alloy is settled, slag is separated from silver gold-bearing alloy, which is directed to silver refining by means of electrolysis in nitro-acid electrolyte. Electrolysis products are refined cathodic silver and golden sludge, which is refined by well-known methods.

EFFECT: removing of detrimental impurities, essentially, zinc, selenium and tellurium made of initial cyanic sediment.

1 ex

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