RU2358898C2 - Method for separation of elemental sulphur and sulphide concentrate from intermediate products of sulphide concentrates hydrometallurgy processing - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method for separation of the elemental sulphur and sulphide concentrate from the intermediate products of the sulphide concentrates hydrometallurgy processing includes sulphur-sulphide flotation of the intermediate original pulp in order to separate the sulphur and sulphides from intermediate oxide components with forming of the sulphur-sulphide concentrate. Then the autoclave disintegration of the sulphur-sulphide concentrate pulp is carried out in the presence of reagent - sulphide hydrophilisator and at the temperature higher than melting point of the elemental sulphur. After that the sulphur flotation is carried out in order to separate the disintegrated pulp into sulphur and sulphide concentrates. Before the sulphur-sulphide and sulphur flotations the pulp undergoes the additive agitation with the reagents, the disintegration is carried out at the temperature 140-150°C.

EFFECT: effective separation of the sulphur and sulphide concentrates.

5 cl, 3 dwg, 1 tbl

Description

The invention relates to methods for processing autoclave leach residues of sulfide materials of non-ferrous metallurgy and can be used to separate elemental sulfur formed on leaching from oxidized pulp to produce sulfur and sulfide concentrates.

There is a method of separating elemental sulfur from hydrated pulp of an autoclave oxidative leaching of a pyrrhotite concentrate [Y. M. Schneerson and others. A method for producing sulfur and sulfide concentrates. Copyright certificate 1303549, MKI C01B 17/027]. The method includes the following operations: collective flotation of sulfur and sulfides into a sulfur sulfide concentrate, disintegration and sulfur flotation, the products of which are sulfur and sulfide concentrates. Sulfur concentrate goes to autoclave smelting of sulfur, and sulfide concentrate goes to pyrometallurgical processing together with ore nickel concentrate. The method involves the use of relatively cheap and safe lime (CaO) and the addition of organic surfactants as a hydrophilizer for disintegration operations.

The closest in technical essence is the prototype method for the separation of elemental sulfur and sulfide concentrate from hydrated pulp of autoclave oxidative leaching of pyrrhotite concentrate [V.N. Fedorov, A.N. Gurov, Zh.I. Rozenberg, Yu.Ya. Sukhobaevsky. Mastering the technology of autoclave oxidative leaching of pyrrhotite concentrates. Non-ferrous metals, 1983, No. 12, p.1-4].

The method is based on autoclave-flotation methods for processing oxidized pulp of autoclave leaching of pyrrhotite concentrate and includes the following operations: collective flotation of sulfur and sulfides into sulfur-sulfide concentrate (CCK), disintegration of CCK and sulfur flotation, the products of which are sulfur and sulfide concentrates. Sulfur concentrate goes to autoclave smelting of sulfur, and sulfide concentrate goes to pyrometallurgical processing together with ore nickel concentrate. Sulfur sulfide flotation is carried out in an acidic environment at pH ~ 4. The tail pulp is neutralized and pumped into the tailing dump. Disintegration of the sulfide sulfide concentrate is carried out at 115-130 ° С, pH 9 ÷ 10 with the supply of an alkaline reagent-hydrophilizer Na ₂ S. The final separation of elemental sulfur and sulfides occurs on sulfuric flotation of the disintegrated pulp, which is also carried out in an alkaline medium at pH 9 ÷ 10.

The method provides a high sulfur content in sulfuric concentrate (> 70%) with a minimum content in sulfide residue (~ 3-5%).

The disadvantage of these methods is that they are worked out for sulfide raw materials that do not have FeS ₂ pyrite in their composition. The main phases of such raw materials are hydrated forms of iron (~ 60 ÷ 70%), non-ferrous metal sulfides (Ni, Cu, Co), pyrrhotite and elemental sulfur. If raw materials contain pyrite (as, for example, in Ural zinc concentrates), then the separation of elemental sulfur and sulfides by the above method does not occur. In addition, it is associated with the use of an expensive and toxic reagent-hydrophilizer (sodium sulfide) for disintegration operations in large quantities (~ 35 kg / t of source material for sulfosulfide flotation).

The difficulty in the separation of pyrite and elemental sulfur is due to the following facts. Firstly, pyrite, like elemental sulfur, has a naturally high hydrophobicity and belongs to easily floated sulfide minerals. Secondly, the hydrophobicity of pyrite increases when it is treated with sulfuric acid [S.I. Mitrofanov. Selective flotation. Moscow, 1958, 726 pp.], As well as when coated with molten sulfur as a result of its high wettability. It is this treatment that occurs on the high-temperature sulfuric acid leaching of zinc concentrate.

The objective of the invention is the separation of elemental sulfur from the autoclave leaching cakes of zinc production, the main phases of which are: elemental sulfur (~ 25-35%), pyrite (~ 15-25%) and jarosite lead (up to 20%). The content of precious metals (BM) in this cake does not allow to consider it dump. The return of a product rich in elemental sulfur (autoclave leaching cake) to the pyrometallurgical production does not meet environmental requirements to reduce emissions of sulfur dioxide in the atmosphere, and also complicates the operation of dust collecting equipment and leads to its premature failure.

The technical result of the invention is the separation of sulfur concentrate suitable for sulfur smelting (that is, containing at least 70% S °), and the production of sulfide concentrate concentrating up to 80% of the noble metals of the initial leach cake, with a minimum content of elemental sulfur (1 ÷ 10 %). This material can be sent to the pyrometallurgical redistribution in order to retrieve valuable components (copper, BM) without violating environmental requirements.

The problem is solved in that the separation of elemental sulfur from the oxidized pulp leaching of zinc concentrate is carried out by additional processing of the material with reagents before each flotation operation, as well as by increasing the temperature of disintegration.

According to studies using an Axioplan Zeiss microscope, the bulk (~ 60%) of elemental sulfur in the material is in a free state. The rest of it is associated with pyrite in the form of conglomerates of various sizes, less often with single grains of chalcopyrite. Pyrite grains destroyed during leaching are covered with a rim of elemental sulfur, in addition, elemental sulfur fills its cracks, due to the high wettability of this sulfide by molten sulfur. Only an insignificant part of pyrite is in a free state in the form of grains of various sizes. Such features of the mineralogical structure of the starting material in combination with a high pyrite content necessitate its additional processing before flotation separation, as well as an increase in the temperature of disintegration.

From the above it follows that the main difficulty is the choice of modes of operations that ensure the separation of elemental sulfur and pyrite.

From the practice of sulphide ore dressing, it is known that lime is the cheapest and most widely used pyrite depressant. The agitation time of flotation pulp with lime before selective flotation can vary from one to several hours [S.I. Mitrofanov. Selective flotation. Moscow, 1958, 726 p.].

For sulfur flotation, hydrocarbon collectors are usually used: kerosene and other petroleum products. Despite the fact that during calcareous depression, the pyrite surface is partially covered with gypsum, the use of hydrocarbon collectors enhances the flotation activity of this sulfide. Therefore, the use of this type of collectors for elemental sulfur in this case is inefficient.

The problem is solved by using another reagent - a depressant and a hydrophilizer of sulfide minerals - sodium sulfide, used in the enrichment of sulfur cakes of hydrometallurgy [Mantsevich MI Development of the theory and practice of flotation of nickel-pyrrhotite raw materials in combined and traditional schemes for its processing. The dissertation for the degree of Doctor of Technical Sciences. M., 1995].

The consumption of sodium sulfide, corresponding to a pulp pH greater than 9.5 and its concentration in the solution of ~ 0.8 ÷ 1.5 g / l, provides the value of the redox potential of the pulp Eh = -560 ÷ -360 mV relative to the silver chloride electrode. Under these conditions, elemental sulfur retains flotation activity and passes into the foam product without the use of hydrocarbon collectors, and sulfide and oxide components remain in the chamber flotation product. Unlike the analogue method, where sodium sulfide is used for disintegration (at a temperature of 115-130 ° C), in the proposed method this reagent is used only on sulfosulfide flotation carried out at room temperature, and most importantly, in much smaller quantities: ~ 7 kg / t of the feed to the sulfosulfide flotation.

Sulfur concentrate is subject to additional separation into sulfur and sulfide components. This material is subjected to an alkaline treatment, called disintegration, at a temperature above the melting point of elemental sulfur. When alkaline reagent is added in the heated pulp, sulfides are hydrophilized, which creates the prerequisites for their further separation from elemental sulfur by flotation.

Elevated temperature and alkaline environment lead to some dissolution of sulfur in the reactions:

The most likely form of polysulfide sulfur is pentasulfide - CaS ₅ .

Along with the polysulfide (S _n ^2- ) and thiosulfate (S ₂ O ₃ ^2- ) forms, part of the sulfur dissolves with the formation of monosulfide (S ^2- ) or HS ^- ions:

The presence of sulfide ions in the liquid phase contributes to the wettability of the solution of solid particles represented by sulfide residues. Elemental sulfur remains hydrophobic. All this creates the conditions for further separation of sulfur and sulfides by flotation.

However, for carrying out sulfuric flotation according to the proposed method, preliminary processing of the pulp is necessary with reagents - pyrite depressants, as well as before sulfur sulfide flotation.

Thus, the technological scheme of the proposed method includes additional operations: agitation of the pulp with reagents before each flotation. The diagram is presented in figure 1.

The above is confirmed by the following examples.

Experiments on the implementation of the prototype method and the proposed method was carried out on samples of the leach residue of zinc concentrate containing,%: Zn 1.5-4.0; Cu 1.4-2.3; Pb 2.4-3.6; Fe 17-21; S ° 27-30, noble metals in quantity, g / t: Au 2.7-5.5; Ag 180-210.

The first flotation enrichment (sulfur-sulfide flotation) was carried out on laboratory pneumatic-mechanical machines of the brand 237-FL with removable chambers with a volume of 1 l; 0.75 liters and 0.5 liters to maintain a certain density in flotation operations, as well as on machines of the brand "Mechanobr" with a chamber volume of 3 liters.

Processing (agitation) of the pulp of the starting material (solid content 50%) with reagents before flotation was carried out in a beaker with a stirrer, the rotation speed of which was 700 rpm. The size of the lime used was 99% of the class - 0.074 mm. The loading of lime in a glass with a stirrer was carried out in dry form, and sodium sulfide in the form of a 10% solution. Consumption was determined by maintaining the pH at a given level.

The solid content in the sulfosulfide flotation was set in the range of 30-20%.

After the flotation experiment, the obtained products were filtered off, the solid was dried in an oven to constant weight at a temperature of 80-85 ° С, the weight was fixed to calculate the yields of each product. Prepared product samples were subjected to chemical analysis for elemental sulfur.

Scheme sulfosulfide flotation is presented in figure 2.

Investigations of the disintegration process were carried out in a laboratory titanium autoclave of the American company Parr with a volume of 7.5 liters with a liquid to solid phase ratio of 2: 1. As an alkaline reagent, hydrophilizing sulfides, lime was used: with an activity of 81% and a particle size of ~ 0.1 ÷ 1.0 mm. The starting material for disintegration was a sulfosulfide flotation concentrate with elemental sulfur content of 42–47%.

The experiments were carried out as follows. A sample of the starting material (sulfur-sulfide concentrate after flotation), the calculated amount of lime (in pulp form) and the required amount of the liquid phase were loaded into an open autoclave. Then the autoclave was sealed, pressed and heated to the desired temperature (125 ÷ 145 ° С) with the mixer turned on, releasing the gas (up to 0 atm) at a temperature of 90-95 ° С and the mixer turned off.

The moment of reaching the set temperature was considered the beginning of the experiment. At the end of the set time, the autoclave was cooled, the pulp was unloaded into a sealed container (taking a sample of the solution) and sent for further processing - sulfur flotation. The solution was analyzed for the content of monosulfide sulfur S ^{2 -} and total sulfur.

Sulfur flotation experiments were carried out on a successfully disintegrated pulp containing sulfide ion in the liquid phase. Scheme of sulfuric flotation is presented in figure 3.

Both agitation was carried out in two versions: with two reagents (CaO, Na ₂ S) 40 minutes before the main flotation, 25 minutes before re-cleaning; with one reagent (CaO) for 15 minutes each. Reagent consumption was determined by the need to maintain the pH at a given level.

The methodology for preparing products for chemical analysis was similar to that described above for products of sulfosulfide flotation.

The results of experiments on the implementation of the prototype and the proposed method are presented in the table.

It can be seen from the table that on serosulfide flotation of an uncleaned acidic leach residue without preliminary treatment with reagents, material separation does not occur (op. CC1): even the formation of a foam product is not observed. Nor does the cake wash out to pH 6.2: flotation does not occur without preliminary treatment with reagents (op. CC2).

Processing the washed cake with alkaline reagents can increase the pH of the pulp. However, experiments have shown that in order to achieve satisfactory flotation values, the pH of the flotated pulp must be at least 10.5. At pH <10.0, flotation separation of the sulfur-sulfide and oxide components does not occur (op. CC3). At pH values from 10.0 to 10.5, the material is divided into two products, but the extraction of elemental sulfur in the sulfosulfide concentrate does not reach the required values (≥90%), and its content in the flotation tailings exceeds the permissible values and is within 9.0 ÷ 9.5% (op. CC4, 5).

At pH> 10.5, satisfactory indicators of the flotation process were obtained (op. CC6-9): the extraction of elemental sulfur in concentrate ≥95% with its content in it> 40%, and in tailings <5%.

Raising the pH to 13.0 seems inappropriate because it does not lead to a significant improvement in the process (op. CC9), but only to an increased consumption of lime.

The results of experiments on the disintegration of sulfosulfide concentrate (op. D1-3) show that at a temperature of 125-135 ° C reactions (2), (3) do not receive their development. Only thiosulfate forms of sulfur (~ 10 g / l) are present in the solution; there is no sulfide ion (S ^2- ) necessary for the successful course of disintegration. In the absence of a sulfide ion in the liquid phase, the surface of the sulfide particles is not wetted by the solution, sulfides remain hydrophobic and, during subsequent flotation, go into the foam product together with sulfur.

When the temperature rises to 145 ° C, a sulfide ion (op. D4-7) appears in the liquid phase in an amount of ~ 1.6-6 g / l. The presence of a sulfide ion leads to wetting of the surface of sulfides by the solution and, consequently, to subsequent flotation separation of elemental sulfur from them. The primary indicator of the presence of a sulfide ion in the liquid phase is the smell of hydrogen sulfide during depressurization of the autoclave and a yellow strip on filter paper dipped in a disintegrated pulp. The pH of the pulp is in the range of 8-9.

The optimal parameters for a successful process are lime consumption in the range of 65–70 kg / t S ° in the load for operation and a temperature of 145 ° C. An increase in reagent consumption (op. D4) and an increase in temperature (op. D7) lead to an increased conversion of sulfur to solution (~ 10-11%), resulting in an increase in sulfur loss with solutions. In addition, at a temperature of 145-150 ° C, molten sulfur has a minimum viscosity. An increase in temperature above 155 ° C leads to a sharp increase in the viscosity of liquid sulfur, which significantly complicates the separation of sulfur and sulfides.

Thus, disintegration is successful under conditions ensuring the presence of a sulfide ion in solution in an amount of at least 1.6 g / l.

A highly alkaline environment, as well as the presence of a sulfide ion in the pulp, is a prerequisite for the effective implementation of sulfuric flotation. As in the case of sulfosulfide flotation, before each operation it is necessary to contact the pulp with reagents - agitation. A condition for achieving satisfactory performance of the process is the pH of the flotated pulp, determined by the reagent regime of agitation. On sulfur flotation, it should be at least 11.5. At pH <11.0, flotation separation of sulfur and sulfides does not occur (op. SF1, 2). At pH values from 11.0 to 12.0, the formation of a foam product (op. SF3) is observed, but the extraction of elemental sulfur in the concentrate is low (~ 46%), and its content in the flotation tailings is unacceptably high (29.9%).

At a pH of 12.0 (op. SF4), satisfactory indicators of the flotation process were obtained: extraction of sulfur in the concentrate ~ 80% with its content in it ~ 70%. Flotation tails contain ~ 8% elemental sulfur. Despite the relatively high elemental sulfur content in the intermediate (32.9%), this material, when mixed with the tailings of sulfuric (8.1% S °) and sulfur-sulfide (1.0% S °) flotation, forms a combined sulfide concentrate with a content of S ° 9.7%. The yield of this material is less than 25% of the leach cake. Elemental sulfur content in sulfide concentrate (~ 5-10%) allows it to be sent to pyrometallurgical production. In this case, the process of sulfuric flotation can be simplified and implemented in a single operation similar to sulfosulfide flotation.

When processing the leach cake of zinc concentrate according to the proposed technology, it is possible to extract up to 78% elemental sulfur into sulfur concentrate with its content in it of at least 70%. A material with such elemental sulfur content is suitable for autoclaving sulfur using the technology used in the sulfur refining in Norilsk [V.I. Goryachkin, I.M. Nelen, V.A. Shcherbakov, M.I. Mantsevich, A.S. Ladygo , J.M. Schneerson. Hydrometallurgical enrichment of nickel-pyrrhotite concentrate. Non-ferrous metals, 1974, No. 9, p.1-6; M.A. Menkovsky, V.T. Yavorsky. Sulfur technology. - M .: Chemistry, 1985. - 328 p.].

At the same time, one third of the material with elemental sulfur content in it <10%, unlike 30% S ° in the initial leach cake, enters the pyrometallurgy. In addition, this material concentrates more than 85% silver and 75% gold (from the content of these metals in the leach cake), which eliminates their loss.

Claims (5)

1. A method of separating elemental sulfur and sulfide concentrate from intermediate products of hydrometallurgical processing of sulfide concentrates, including sulfur-sulfide flotation of the initial pulp of the intermediate product to separate sulfur and sulfides from the oxide components of the intermediate product with the formation of sulfur sulfide concentrate, autoclave disintegration of pulp of sulfur-sulfide concentrate at a temperature above the melting point of the element sulphide hydrophilizer reagent; sulfur flotation for separation is disintegrated oh pulp on sulfur and sulphide concentrates, characterized in that before sernosulfidnoy and sulfuric flotation pulp is subjected to further agitation with reagents and disintegration is carried out at a temperature of 140-150 ° C. 2. The method according to claim 1, characterized in that the initial pulp of the intermediate product is agitated first with lime, then with sodium sulfide. 3. The method according to claim 1, characterized in that the pH of the pulp entering the sulfur sulfide flotation is maintained at least 10.5. 4. The method according to claim 1, characterized in that the pH of the pulp entering the sulfur flotation is maintained at least 11.5. 5. The method according to claim 1, characterized in that the obtained sulfur concentrate is divided into commercial sulfur and a sulfide product, which is sent into circulation for agitation preceding sulfur flotation.

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