RU2268315C1 - Method of stripping concentrate of platinum group members - Google Patents

Abstract

FIELD: production of platinum group metals by refining.

SUBSTANCE: proposed method includes heat treatment of concentrate mixed with sodium peroxide at gradual rise of temperature to 500-600°C followed by dissolving the product of heat treatment in hydrochloric acid. Heat treatment of mixture is performed in iron trays at mass ratio of sodium peroxide to concentrate containing up to 30% of iridium, ruthenium and osmium of (0.8-1.4) and concentrate containing more than 30% of iridium, ruthenium and osmium of (1.5-2.0). Prior to dissolving the heat treatment product in hydrochloric acid, it is dissolved in water.

EFFECT: deep stripping of concentrate at minimum consumption of reagent - sodium peroxide oxidant.

2 tbl, 2 ex

Description

The method of opening the concentrate of platinum satellites relates to the field of non-ferrous metallurgy, in particular the refining of precious metals.

The initial stage of separation of precious metals and their subsequent refining is the opening of raw materials. The most difficult to transfer to a solution are concentrates with a high content of iridium, ruthenium and osmium. In addition to the listed elements, the composition of concentrates of this type includes other platinum metals and base metals. One of the common methods for opening such concentrates is the heat treatment of their mixture with sodium peroxide and the subsequent dissolution of the resulting product.

A known method of converting metals - satellites of platinum into solution [1], including their heat treatment at a temperature of 973 K with the addition of peroxide and sodium carbonate, followed by leaching of ruthenium and osmium compounds in water, and then iridium and rhodium in hydrochloric acid. The disadvantage of this method is the formation of a melt, due to the high temperature of the heat treatment of the mixture, solidifying upon cooling, as a result of which there are great difficulties in separating the heat treatment products from the surface of the container material.

A known method of converting a concentrate of precious metals into solution [2], including its heat treatment with a four-fold excess of sodium peroxide in a nickel or silver crucible with a gradual increase in temperature and subsequent dissolution of the alloy in water. This method is widely used for analytical purposes. The disadvantage of the method when it is used on an industrial scale is the difficulty of separating the solidified melt from the crucible, the use of expensive crucibles, as well as the incompleteness of the transfer of metals into solution.

A known method of opening a concentrate of platinum metal-satellites [3], including its alloying with the addition of a 3-5-fold excess of sodium peroxide with a gradual increase in temperature to (500-600) ° C and subsequent dissolution of the heat-treated products in dilute hydrochloric acid. This method is adopted as a prototype. The disadvantages of the method are the irrational consumption of the reagent sodium peroxide, obtaining a hard-loaded solidified melt, violent interaction of an alkaline product when it is dissolved in hydrochloric acid.

The technical result, the achievement of which the present invention is directed, is to reduce the consumption of an oxidizing agent - sodium peroxide, replacing expensive container materials, as well as obtaining a convenient heat treatment product in operation.

The desired technical result is achieved by the fact that in the method of opening the concentrate of platinum satellites, including its heat treatment in a mixture with sodium peroxide with a gradual increase in temperature to (500-600 ° C) and subsequent dissolution of the heat treatment product in hydrochloric acid, according to the invention, the mixture is heat treated in iron baking sheets at a mass ratio of sodium peroxide to a concentrate containing up to 30% iridium, ruthenium and osmium, (0.8-1.4), and a concentrate containing more than 30% iridium, ruthenium and osmium, at (1.5-2, 0), and before sol rhenium in hydrochloric acid, the heat treatment product is dissolved in water.

The essence of the method is as follows. Solids of platinum metals, such as Me ₂ O ₂ * nNa ₂ O and Me ₂ O ₃ * nNa ₂ O, are formed during heat treatment of a mixture consisting of a concentrate of platinum satellites and sodium peroxide. Specially conducted experiments have shown that with a total mass fraction of concentrate iridium, ruthenium and osmium up to 30%, the required completeness of opening is achieved after heat treatment of the mixture with a mass ratio of sodium peroxide to the concentrate component (0.8-1.4). If the total mass fraction in the concentrate of iridium, ruthenium and osmium is more than 30%, then this ratio is (1.5-2.0). The completeness of opening the concentrate at a ratio of the components of the charge greater than 2 does not significantly increase, but in this case, during the heat treatment, a melt is formed that adheres firmly to the pan, which causes great difficulties in subsequent processing operations. With a lower oxidizing agent consumption, a cake that is convenient for operation and easily detachable from the baking sheet is obtained, however, when the mass ratio of sodium peroxide to the platinum satellite concentrate is less than 0.8, the completeness of metal opening is noticeably reduced.

The resulting heat treatment product is dissolved first in water and then in hydrochloric acid. With this sequence of operations, it is possible to avoid a violently occurring exothermic reaction between alkaline cake and acid. In addition, if the initial concentrate contains osmium, then when the obtained cake is treated with water, it passes into a solution and, if necessary, it can be separated before treatment with hydrochloric acid.

The conditions in which the heat treatment of the mixture is carried out allows the use of iron baking sheets instead of silver or nickel, which is much more profitable from an economic point of view.

EXAMPLE 1

For opening, they took a concentrate of platinum satellites, containing,%: Rh - 0.5; Ir - 12.5; Ru - 8.7.

Several samples of such a concentrate weighing 10 g each were sewn with sodium peroxide at different weight ratios. The mixture was placed in iron baking sheets, heated to a temperature of 550 ° C and kept at this temperature for 2 hours. Then the baking sheets were cooled, the heat-treated products were transferred to glasses, poured with water, stirred for 60 minutes, treated with hydrochloric acid, heated for 60 minutes, cooled, the insoluble residue was filtered off, dried and weighed. The content of rhodium, iridium, and ruthenium was determined: in solution by emission-coupled plasma (ICP), and in insoluble residue by spectral analysis. The results are presented in table 1.

Table 1
Metal distribution during dissolution of heat treatment products of a concentrate of platinum satellites with sodium peroxide. Experience number Mass ratio of Na ₂ O ₂ / concentrate Product Name Distribution% Rh Ir Ru one 0.4 Solution 43 67 59 Insoluble residue 57 33 41 2 0.8 Solution 73 95 91 Insoluble residue 27 5 9 3 1.4 Solution 75 97 94 Insoluble residue 25 3 6 four 3.0 Solution 76 98 96 Insoluble residue 24 2 four

EXAMPLE 2

For opening, they took a concentrate of platinum satellites (ie, from the dissolution of schlich platinum), containing,%: Rh - 1.5; Ir - 20.8; Ru - 2.6; Os - 18.7.

Several samples of such a concentrate weighing 10 g each were sewn with sodium peroxide at different weight ratios. The mixture was placed in iron baking sheets, heated to a temperature of 550 ° C and kept at this temperature for 2 hours. Then the baking sheets were cooled, the heat-treated products were transferred to glasses, poured with water, stirred for 60 minutes and filtered. The insoluble residue was treated with hydrochloric acid, warmed for 60 minutes, cooled, filtered. The insoluble residue was dried and weighed. The content of rhodium, iridium, and ruthenium was determined: in solution by emission-coupled plasma (ICP), osmium by the photocalorimetric method, and in the insoluble residue by spectral analysis. The results are presented in table 2.

table 2
Metal distribution during dissolution of heat treatment products of a concentrate of platinum satellites with sodium peroxide. Experience number Mass ratio of Na ₂ O ₂ / concentrate Product Name Distribution% Rh Ir Ru Os one

0.6 Water solution 0 3 5 68.3 Hydrochloric acid solution 38.4 34.7 36.6 6.5 Insoluble residue 61.6 62.3 58.4 25.2 2

1.5 Water solution 0 4.4 49.1 93.5 Hydrochloric acid solution 91.2 89.8 47.3 5.0 Insoluble residue 8.8 5.8 3.6 1.5 3

2.0 Water solution 0 4.0 33.4 98.3 Hydrochloric acid solution 95.1 92.8 62.5 1.7 Insoluble residue 4.9 3.2 4.1 1.0 four

3.0 Water solution 0 4.5 46.8 97.8 Hydrochloric acid solution 96.7 93.2 50.5 1.8 Insoluble residue 3.3 2.3 2.7 0.4

As can be seen from the above examples, the use of the proposed method allows to achieve deep opening of the concentrate of platinum satellites with a minimum consumption of an oxidizing agent reagent - sodium peroxide.

Information sources

1. Yu.A. Kotlyar, M.A. Meretukov. Metallurgy of precious metals. Tutorial. M .: ASMI, 2002, p. 389.

2. S.I. Ginzburg, K. A. Gladyshevskaya, N. A. Ezerskaya and other Guidelines for the chemical analysis of platinum metals and gold. M .: Nauka, 1965, p. 264.

3. S. I. Ginzburg, N. A. Ezerskaya, I. V. Prokofiev and others. Analytical chemistry of platinum metals. M .: Nauka, 1972, pp. 25-26.

Claims (1)

The method of opening the concentrate of platinum satellites, including its heat treatment in a mixture with sodium peroxide with a gradual increase in temperature to (500-600) ° C and the subsequent dissolution of the heat treatment product in hydrochloric acid, characterized in that the heat treatment of the mixture is carried out in iron baking sheets at a mass ratio of sodium peroxide to a concentrate containing up to 30% iridium, ruthenium and osmium, (0.8-1.4), and a concentrate containing more than 30% iridium, ruthenium and osmium, at (1.5-2.0), and before dissolution in hydrochloric acid the heat-treated product of sol rip in the water.