RU2355792C2 - Method of products reprocessing, containing chalcogenides of base metals, lead, platinum metals, gold and silver - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: invention relates to noble metals metallurgy and can be used for reprocessing of different wastes of refining, such as dust-fumes or water-insoluble residues of dust-fumes. Method of products reprocessing, containing chalcogenides of base metals, lead, platinum metals, gold and argentum includes leaching of initial product in solution of caustic soda, separation of received alkaline solution from insoluble residue. Insoluble residue is subject to melting with addition of manufactured products of refining, sodium-bearing flux and carbonaceous reductant. After melting it is implemented grinding of separated bottom heavy phase into the powder and its treatment as a concentrate of refining. Into received during leaching initial products alkaline solution it is added sulfuric acid up to pH=4-6, it is separated laid-down from the solution deposit of hydroxides on the basis of tellurium dioxide. Solution after the sediment separation is again treated by sulfuric acid up to pH=1-2, it is added sodium sulfite and separated laid-down deposit of metal selenium, and mother solution is subject to finishing de-refining. ^ EFFECT: cost cutting while de-refining of received during the reprocessing solutions. ^ 1 ex

Description

The invention relates to the metallurgy of noble metals (BM) and can be used in the technology of refining metals of the platinum group (PGM).

Various inappropriate products and wastes are inevitably generated at refineries, containing PGM, silver, gold, in particular, such as dust collectors or water-insoluble residues of dust collectors (i.e. dust collectors), which enter the dust and gas tunnel and the gas purification system from various technological sites and process areas .

A characteristic feature of dust shelters or n.o. Dust collectors is that their base is represented by a large number of different chemical elements and their compounds, mainly volatile chalcogenides of base metals, ammonium and silver chlorides, lead, soot carbon. This intermediate product contains from 0.5 to 3% PGM (in total), from 0.05 to 0.2% gold, from 3 to 10% silver, from 10 to 20% lead, from 4 to 8% selenium, from 6 up to 10% tellurium, from 2 to 4% arsenic. Recycling dust shelters or n.o. Dust collection presents significant difficulties and is associated with large material and labor costs.

From generally available literature it is known that the processing of dust can be carried out by the pyrometallurgical method - by melting a mixture containing soda, borax, glass and, in some cases, coal as fluxes, and copper is used as a collector of precious metals [Fundamentals of Metallurgy. T.5. - M .: Metallurgy, 1968. P.316].

The disadvantages of this analogue method when it is used for processing dust refineries of refining production, containing along with BM significant amounts of non-precious metal chalcogenides, should be attributed:

- the formation during smelting of large quantities of secondary dust combustors enriched with volatile chalcogenides, containing BM and in need of processing;

- the transition of chalcogenides during smelting to the target BM alloys, which increases their mass, reagent consumption and labor for refining.

A known method of processing products containing chalcogenides of base metals, lead, platinum group metals, gold and silver, according to which the initial product is leached in a solution of caustic soda, the resulting alkaline solution is separated from the insoluble residue, the latter is melted with additives of refining intermediates, sodium fluxes and a carbon reducing agent , the melt is defended and cooled to solidification, the solidified product is separated along the phase boundaries, ground bottom is crushed and processed yellow phase as a concentrate of refining production [RF Patent No. 2291212, Efimov V.N., Temerov S.A., Moskalev A.V., Churkin V.A., Gubin M.V. - BI No. 1, 2007]. This method is the closest in technical essence to the claimed method and adopted as a prototype.

The use of the prototype method for the processing of dust collectors or n.o. Dust collectors of refining production, along with a number of positive features, are associated with the following negative consequences. When the initial product is leached in a solution of caustic soda, not only the majority of the contained chalcogenes (selenium, tellurium) and arsenic are converted into an alkaline solution, thereby achieving a beneficial enrichment of the insoluble residue sent to the smelting, but also some, relatively small (20-30 mg / l) the amount of PGM.

In this regard, all obtained alkaline solutions are inevitably subject to final decontamination by cementitious treatment. However, the high saturation of the solutions with chalcogenes (tellurium and selenium) leads to an increased consumption of cementing agent, an increase in the mass of the target product returned to refining - cementate, undesirable contamination of the latter with chalcogenes, arsenic and lead, and, as a result, high labor costs for finishing decontamination of solutions and processing of the resulting cementate.

The proposed method is aimed at obtaining a technical result, which consists in reducing the cost of finishing decontamination of solutions obtained by leaching products containing non-precious metal chalcogenides, lead, platinum group metals, gold and silver, in a solution of caustic soda.

The achievement of the technical result is ensured by the fact that in the alkaline solution obtained by leaching the initial product in caustic soda, after it is separated from the insoluble residue, sulfuric acid is added until the solution reaches a pH of 4–6, the precipitate of tellurium hydroxides precipitated from the solution is separated , then the solution is again treated with sulfuric acid until the solution reaches a pH of 1-2, the sodium sulfite salt is added, the precipitate is separated metal go selenium, and the mother liquor is subjected to final decontamination.

Thus, before the decontamination operation, the precipitate of tellurium dioxide-based hydroxides is gradually removed from the alkaline solution, then metal selenium, and the remaining mother liquor is subjected to final decontamination. At the same time, the consumption of cementing agents, the yield of obtained cementates, and the costs of their processing are reduced. Two new products can be derived from the refining cycle: a mixture of tellurium dioxide-based hydroxides and metallic selenium.

Usage example.

We took 63 g of wet (W = 42.8%) starting material (n.a. dust collectors - the so-called "electrostatic dust concentrate") containing chalcogenides of base metals, lead, platinum group metals, gold and silver. According to the analysis, the initial product (by dry weight) contained, wt.%: Pt - 0.53; Pd 0.79; Rh 0.03; Ir - 0.01; Ru - 0.04; PGM (in total) - 1.40%; Au - 0.13; Ag - 5.8; Te is 7.2; Se 6.5; Sn - 4.5; As-2, 6; Pb - 14.5; Cu - 0.96; Sb 2.9; Fe - 3.9%.

The initial product was leached in a solution of caustic soda, and the alkaline solution was separated by filtration from the insoluble residue. In this case, two products were obtained — an alkaline solution in an amount of 300 ml and an insoluble residue. The yield of the latter (by dry weight) was 20.0 g or 55.6% of the starting product launched for leaching. According to the analysis, the content of BM in n.o. amounted to,%: Pt - 0.93; Pd - 1.40; Rh 0.05; Ir 0.017; Ru - 0.067; Au 0.23; Ag - 10.44. Thus, the content of PGM, gold and silver (in total) increased and amounted to 13.13%, which is 1.79 times higher than in the starting material before leaching.

Base elements passed into the caustic soda solution from the initial product. According to the results of the analysis, their concentration in solution was, g / l: Te - 7.11; Se - 6.23; Sn - 2.21; As - 2.55; Pb - 5.39; PGM (in total) - 17 mg / l. Thus, 82.2% of tellurium, 79.8% of selenium, 40.9% of tin, 81.6% of arsenic and 31.0% of lead passed into the solution from the initial product. Copper, iron, and antimony remained predominantly in the insoluble residue.

The alkaline solution was treated with concentrated sulfuric acid until a pH of pH 5 was established and the precipitate based on tellurium dioxide precipitated from the solution. At the same time, 300 ml of a solution and 5.38 g (by dry weight) of a precipitate were obtained, which contained,%: Te - 38.5; Se 6.3; Sn - 11.7; As - 1.8; Pb - 27.8.

The concentration of base elements in the solution after the separation of hydroxides was, g / l: Te - 0.2; Se - 5.1; Sn is 0.1; As - 2.3; Pb - 0.4; PGM (in total) - 14 mg / l.

Concentrated sulfuric acid was added to the resulting solution until a pH of pH 1.5 was established, then 6 g of sodium sulfite was added. The solution was kept under stirring for 2 hours and the precipitate of selenium metal precipitated from the solution was separated by filtration. In this case, 1.39 g (by dry weight) of selenium containing 99.4% of the basic substance and 300 ml of the solution, which contained according to the analysis, g / l were obtained: g / l: Te - 0.19; Se - 0.44; Sn is 0.1; As - 1.9; Pb - 0.4; PGM (in total) - 11 mg / l. This solution is aimed at finishing decontamination.

Thus, 97.2% of tellurium, 93.0% of selenium, 95.5% of tin, 25.8% of arsenic and 92.6 are removed from the initial alkaline solution and, therefore, from the refining cycle to the precipitated two products. % lead.

Proposed in the inventive method, the preliminary cleaning of the solution to be decontaminated from the majority of impurities of base elements greatly simplifies the final deposition of PGM by cementation. The consumption of cementing agent is reduced, since the latter is not spent on the precipitation of chalcogenes, lead and tin, the content of PGMs in the resulting cement is increased, and the costs of their subsequent refining are reduced.

The obtained precipitate of selenium can be used in the production of additional commercial products - metallic selenium.

The remainder of the initial product that was not dissolved in caustic soda (i.e., pulverized dust) was further processed according to the technology provided for by the prototype method (without any differences).

For this purpose, the residue insoluble in caustic soda was mixed with the addition of the intermediate product of the refining production obtained by cementing the solutions of the refining production (the so-called cementate containing copper and iron, along with PGM).

This cementate contained, wt.%: Pt - 1.11; Pd - 1.59; Rh 0.18; Ir 0.08; Ru 0.24; PGM (in total) - 3.20%; Au - no; Ag - no; Se 6.5; Those are 2.5; Cu - 18.2; Fe - 10.1%.

The cementate additive was taken in an amount of 20 g, i.e. 100% by weight of the initial product that did not dissolve in caustic soda (the so-called “electrostatic dust concentrate”) Sodium-containing fluxes (8 g of ground sodium silicate glass, 4 g of soda ash) and 2 g of a carbonaceous reducing agent, coxic, were added to the two products taken. All components of the charge were mixed and loaded into a melting alundum crucible. The crucible was placed in a shaft laboratory electric furnace and subjected to isothermal exposure (melting) for 45 minutes at a temperature of 1300 ° C. At the end of the melting, the crucible was unloaded from the furnace.

After cooling, the hardened product was removed from the crucible, which was divided according to the formed phase boundaries. In this case, it was received:

- 2.64 g of the bottom heavy phase - the target alloy of platinum metals and gold with the following content of the analyzed elements (according to ICP),%: Pt - 15.28; Pd 21.55; Rh 1.70; Ir 0.70; Ru - 2.08; PGM (in total) - 41.31%; Au - 1.14; Ag - 3.45; Se - 0.76; Te is 1.6; Sn 6.29; As - 2.12; Pb - 7.95; Cu - 5.42; Sb - 22.0 Fe - 0.20%;

- 12.75 g of a matte-like light alloy containing (according to ICP),%: Pt - 0.036; Pd 0.225; Rh — 0.007; Ir 0.007; Ru - 0.047; PGM (in total) - 0.322%; Au - 0.12; Ag - 15.65; Se - 10.82; Te - 5.17; Sn 4.35; As 0.63; Pb - 18.95; Cu 29.17; Sb 1.31; Fe - 8.21%;

- 21.7 g of sodium silicate slag that does not contain (according to spectral analysis) platinum group metals and gold.

The rich target alloy was recovered,%: Pt - 98.85; Pd - 95.20; Rh 97.94; Ir 95.11; Ru 89.52; the amount of PGM is 96.36%. This target alloy is crushed into powder and processed as a concentrate of refining production.

A matte-like light alloy, in which about 78% of selenium, 69% of tellurium, 94% of copper, 81% of lead and 31% of iron (from the amounts launched into the smelting) is recovered, is processed using known methods.

Thus, the use of the proposed method of processing products containing chalcogenides of base metals, lead, platinum group metals, gold and silver, including leaching the initial product in a solution of caustic soda and providing for the preliminary stage-by-stage cleaning of the alkaline solution to be decontaminated from most of the impurities of base elements (mainly , from selenium and tellurium), - greatly simplifies the final deposition of PGM by cementation, reduces cement consumption agent, increase the PGM content of the precipitate obtained, reduce cost of their subsequent refining and receive the selenium precipitate, which can be used in the production of more marketable products.

Claims (1)

A method of processing products containing base metal chalcogenides, lead, platinum group metals, gold and silver, including leaching the initial product in a solution of caustic soda, separating the resulting alkaline solution from an insoluble residue, melting an insoluble residue with additives of refining intermediates, sodium fluxes, and a carbonaceous reductant sedimentation and cooling of the melt until solidification, separation of the hardened product at the phase boundaries, grinding selected of the ground heavy phase into powder and its processing as a concentrate of refining production, characterized in that sulfuric acid is added to the alkaline solution obtained by leaching the initial product in caustic soda after it is separated from the insoluble residue until the solution reaches a pH of 4–6 of the medium, and it is separated the precipitate of tellurium dioxide hydroxides precipitated from the solution, after separation of the precipitate, the solution is again treated with sulfuric acid until the solution reaches a pH of 1-2, Adds sodium sulfite, separating the precipitate of metallic selenium, and the mother liquor is subjected to the finishing obezblagorazhivaniyu.