Method for processing materials comprising platinum and palladium

Abstract

FIELD: chemical-metallurgical production.SUBSTANCE: invention to methods for processing materials comprising platinum and palladium. The method includes leaching said material in a solution of hydrochloric acid with a concentration of 6-8 mol / dm3 at a temperature of 85-100 °C for 2-4 hours, obtaining a pulp comprising precious metals. The resulting pulp is subjected to oxidative treatment, after which the undissolved residue is separated from the solution comprising platinum and palladium by filtration. The undissolved residue is subjected to reducing melting, followed by grinding of the resulting alloy and return to oxidation treatment. Moreover, the solution comprising platinum and palladium is fed for further processing.EFFECT: increase in the extraction of precious metals and a reduction in the amount of material supplied for smelting, leading to an acceleration in the production of finished products.2 cl, 5 ex

Description

[0001] The invention relates to chemical-metallurgical production, in particular to methods for processing materials containing platinum and palladium.

[0002] Platinum and palladium, the main components by mass, are partially present in the materials as an oxide phase (PdO), while the remainder is in metallized form, in the form of chalcogenides, compounds with arsenic and antimony. Palladium oxide is formed as a result of heat treatment in the preceding stages; the more the material is calcined, the more resistant the palladium oxide is to solvents.

[0003] The primary objective of processing platinum and palladium-containing materials is to maximally convert valuable components into water-soluble compounds for subsequent selective extraction. Typically, the conversion of precious metals into a solution is carried out in a hydrochloric acid medium in the presence of an oxidizing agent (chlorine, nitric acid, etc.).

[0004] To convert platinum and palladium into soluble compounds, reduction smelting is used, in particular, where the metals are converted into elemental forms and then subjected to leaching. This processing scheme is labor-intensive and multi-step.

[0005] There is a "Method for Processing Precious Metal Concentrate" [RU Patent 2094499 C1 IPC C22B 11 / 00, published 10 / 27 / 1997] based on silicon and palladium oxides, according to which, before dissolution, the concentrate containing oxide phases and silica is charged with a carbon-containing reducing agent, the charge is heated to form a sinter, and the sinter is chlorinated in a hydrochloric acid solution. According to the authors, when using this method, the extraction of palladium into solutions increases from 60 to over 98%. A disadvantage of this method is the presence of high-temperature processes in the process flow, which are expensive and lead to the accumulation of a large amount of materials, thereby increasing the processing time of the materials.

[0006] There is a “Method for producing palladium compounds” [RU Patent 2201462 C2 IPC C22B 11 / 00, C22B 3 / 10, published 03 / 27 / 2003], which includes calcining metallic palladium in the form of powder or its salts in a stream of oxygen-containing gas, resulting in the formation of palladium oxide, and its subsequent dissolution in hydrochloric acid.

[0007] The conversion of palladium from its oxide form to solutions by reacting it with hydrochloric acid solutions at high temperatures is a common feature with the proposed method. However, the purpose of this invention is to produce commercial palladium compounds, as well as other forms of the components in the raw materials, which differs from the proposed method.

[0008] A "Method for Extracting Platinum Metals from Platinum-Containing Concentrates" is known [RU Patent 2169200 C1 IPC C22B 11 / 00, C22B 3 / 10 published 20.06.2001 Bulletin No. 17], which includes oxidative roasting of concentrates, hydrochloric acid leaching of the cinder with the transfer of platinum metals into a chloride solution and the subsequent separation of platinum metals from the solution. Leaching of the cinder is carried out in the presence of an activating additive that ensures the removal of oxide passivating films from the surface of platinum metal grains, at a consumption of 5-10% of the cinder weight, while hydrazine hydrochloride or sodium sulfite are used as the activating additive. The disadvantages of this method include the need for large volumes of materials to be fed into the firing operation, as well as the use of activating additives, including hydrazine hydrochloride, which is a highly toxic substance.

[0009] The closest technical solution selected as a prototype is the “Method for processing concentrates based on base elements containing rare metals of the platinum group” [patent. RF 2773294 C1 IPC C22B 11 / 00, published 01.06.2022 Bulletin No. 16], which includes pulping in water, treatment with acid, then treatment with an oxidizing agent until the required ORP values ​​are achieved, separation of the undissolved residue, chlorination of the undissolved residue.

[0010] The technical result, which the proposed invention is aimed at achieving, is an increase in the extraction of DM and a reduction in the amount of material supplied for smelting, which leads to an acceleration of the release of finished products and a reduction in processing costs.

[0011] The specified technical result is achieved by the fact that the method for processing materials containing platinum and palladium includes the following operations:

[0012] a. leaching in a saline solution to obtain a pulp containing precious metals;

[0013] b. oxidative treatment of the obtained pulp, after which the undissolved residue is separated from the solution containing platinum and palladium by filtration, characterized in that:

[0014] Leaching is carried out in a hydrochloric acid solution with a concentration of 6-8 mol / dm3 3 at a temperature of 85-100°C for 2-4 hours, and after oxidative treatment, the following stages are carried out:

[0015] c. reducing smelting of the undissolved residue obtained in step b, followed by grinding the resulting alloy and returning to step b;

[0016] d. Processing the solution obtained in step b containing platinum and palladium. Liquid-phase chlorination or

[0017] exposure to a mixture of hydrochloric and nitric acids.

[0018] The essence of the invention is that under the specified conditions and sequence of operations, a reduction of materials is achieved due to the maximum transfer of valuable components into solution.

[0019] The dissolution of palladium oxide occurs due to interaction with hydrochloric acid:

[0020]

[0021] Thus, to achieve the technical result, there is no need to carry out additional restoration operations using high-temperature processes.

[0022] The claimed method is carried out as follows: materials containing platinum and palladium are loaded into the reactor together with 6-8 mol / dm 3A hydrochloric acid solution is added, and the pulp is heated to a temperature of 85-100°C, followed by holding. After holding, the reaction mixture (pulp), containing precious metals, undergoes oxidation treatment. The resulting undissolved residue is subjected to reduction smelting, followed by grinding of the resulting alloy and returning it to the oxidation treatment stage. The solutions obtained after oxidation treatment are processed using known methods.

[0023] Liquid-phase chlorination or exposure to a mixture of hydrochloric and nitric acids are used as oxidative treatment.

[0024] Lower limit for the concentration of hydrochloric acid in solution (6 mol / dm 3 ) is due to the fact that a decrease in this parameter will result in an incomplete transition of platinum and palladium into the solution, and the target extraction rate into the solution will decrease.

[0025] Upper limit for hydrochloric acid concentration (8 mol / dm 3) is due to the fact that with an increase in this parameter, the extraction of palladium into the solution does not increase, but during its further processing, difficulties may arise due to the need to neutralize excess acid.

[0026] The lower limit for the holding temperature (85°C) is due to the fact that at lower temperatures the rate of process (1) and (2) is significantly reduced, which leads to an increase in its duration and incomplete transition of platinum and palladium into the solution during subsequent opening.

[0027] The upper limit for the holding temperature (100°C) is due to the fact that with a further increase in temperature, the vapor pressure above the liquid phase increases significantly, and autoclave equipment is required to carry out the operation.

Claims

1. A method for processing materials containing platinum and palladium, comprising: a) leaching in a hydrochloric acid solution to obtain a pulp containing precious metals; b) oxidative treatment of the resulting pulp, after which the undissolved residue is separated from the solution containing platinum and palladium by filtration, characterized in that leaching is carried out in a solution of hydrochloric acid with a concentration of 6-8 mol / dm3 3 at a temperature of 85-100°C for 2-4 hours, and after oxidative treatment, the following stages are carried out: c) reducing smelting of the undissolved residue obtained in step b), followed by grinding of the resulting alloy and returning to step b); d) processing the solution obtained in step b) containing platinum and palladium.

2. The method according to paragraph 1, characterized in that the oxidative treatment is carried out by liquid-phase chlorination or exposure to a mixture of hydrochloric and nitric acids.

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