RU2121517C1 - Method of recovering and separating platinum and palladium - Google Patents

Abstract

FIELD: extractive recovery and separation of platinum and palladium. SUBSTANCE: original hydrochloric acid solution containing at least 5M hydrochloric acid, platinum, palladium and other metals of platinum group is contacted with sulfoxide solution. The resulting extract is washed with hydrochloric acid having 4-5M concentration. Platinum is reextracted with 1-4M hydrochloric acid solution from washed extract. Platinum reextract is made to react with sulfoxide used for extraction purposes. Organic phases resulting from platinum reextraction, and after treatment of platinum reextract with sulfoxide, are combined. Palladium is reextracted with ammonia solution from said phases. Recovery of platinum and palladium is 99.5. Purity of the resulting products is at least 99.98%. The claimed method makes it possible to make process more efficient, to increase recovery and separation of platinum and palladium. EFFECT: more efficient recovery and separation method. 5 cl, 2 ex

Description

 The invention relates to the field of chemical technology of extraction extraction of platinum group metals, in particular platinum and palladium.

 Currently, many extraction methods have been developed for the extraction of platinum and palladium from a mixture of platinum group metals and their subsequent separation.

 The extraction of platinum and palladium from solutions and their subsequent separation can be carried out either by selecting a selective extractant for each of them (SU, patent 1838243, C 01 G 55/00, 1993), or in the process of re-extraction of platinum and palladium from the organic phase during their joint extraction one extractant (Meretukov MA and Orlov AM, Metallurgy of precious metals. Foreign experience. M., Metallurgy, 1991, p. 371).

 The choice of extractants designed for the extraction of platinum and palladium is also varied (Meretukov MA and Orlov AM, Metallurgy of precious metals. Foreign experience. Moscow, Metallurgy, 1991, pp. 360-368).

 However, all these methods have one significant drawback: the extractants used are very expensive and are not produced on an industrial scale, which virtually eliminates their industrial use.

 Closest to the proposed method is a method for the extraction and separation of platinum and palladium from a hydrochloric acid solution by extraction with a secondary amine (US patent 4041126, C 01 G 55/00, 1977).

 Only platinum and palladium pass into the organic phase of the amine Amberlite LA 1 (with the addition of the isodecanol modifier). The content of iridium, rhodium and ruthenium in the organic phase is negligible.

 The separation of platinum and palladium occurs at the stage of re-extraction. Initially, platinum is re-extracted with an alkaline solution of a reducing agent (hydrazine or thiourea).

 The disadvantages of this method are its low productivity, insufficiently high degree of metal separation (the maximum ratio of Pt to Pd in reextraction is 46, that is, the purity of platinum is 97.9%), as well as a low degree of extraction (85% for platinum and 79% for palladium )

 The objective of the invention is to provide such a method for the extraction and separation of platinum and palladium from hydrochloric acid solution, which would result in a high-performance process with a high degree of extraction and separation of platinum and palladium, which in turn will improve the quality of the finished product.

 To solve this problem, in a method for extracting and separating platinum and palladium from a hydrochloric acid solution by extraction and subsequent reextraction from the organic phase, first platinum, and then palladium extraction is carried out from a solution containing at least 5 M hydrochloric acid using sulfoxide as an extractant, and reextraction platinum is carried out with a solution containing 1-4 M hydrochloric acid.

 In addition, the organic phase after extraction is washed with a solution of hydrochloric acid with a concentration of 4-5 M.

 The method also differs in that the platinum re-extract is treated with the sulfoxide used in the extraction, and the palladium re-extraction is carried out from a mixture of organic phases obtained after the platinum re-extraction and after the platinum re-extract is treated with the sulfoxide.

 Reextraction of palladium is a solution of ammonia.

 To implement the method, an initial solution containing platinum and palladium with an acidity of at least 5 M hydrochloric acid is treated with an extractant solution.

 Platinum and palladium pass into the organic phase (extract).

 If necessary, in the presence of impurities that can be coextracted with platinum and palladium in the organic phase (Ir, Rh, Ru, Fe), the extract is washed with a solution of hydrochloric acid with a concentration of 4-5 M. The impurities are washed out, while platinum and palladium remain in organic phase.

 Then the organic phase is treated with a solution of an acid of lower acidity of 1-4 M to re-extract platinum. Platinum goes into the aqueous phase (re-extract).

 The platinum reextract for its purification from palladium can be further treated with the sulfoxide solution used in the extraction. The process can be organized both sequentially, that is, at first platinum re-extraction, and then processing of the stripping with sulfoxide, and in parallel, that is, the operations of platinum stripping and processing of stripping with sulfoxide are carried out simultaneously in one cascade of the extractor.

 The organic phase obtained after re-extraction of platinum and the organic phase after processing the re-extract of platinum with sulfoxide are combined and palladium is re-extracted from the mixture with an ammonia solution.

 The recovery of valuable components is 9.5%, and the purity of the finished products is 99.98%.

 The possibility of using extractants from the class of sulfoxides for extraction, for example, palladium is known from the prior art (Journal of Inorganic Chemistry, 1970, v.15, v.5, pp. 1336-1342, Nikolaev N.V. et al. Extraction properties of organic sulfides and sulfoxides and charge on the sulfur atom).

 However, the problem of extraction and separation of platinum and palladium by this extractant of industrial importance has never been solved before.

где R1 и R2 - алкил, арил, бензил и т.д. или их смесь.The sulfoxides used in the present process can be dioctyl sulfoxide, dimethyl sulfoxide, petroleum sulfoxides, etc. having the general structural formula

where R1 and R2 are alkyl, aryl, benzyl, etc. or a mixture thereof.

 The use of sulfoxide as an extractant allows the extraction process to be carried out at a high speed and with a high extraction of platinum and palladium into the organic phase and their subsequent separation at the stage of re-extraction.

 The method is illustrated by the following examples.

 Example 1. The original hydrochloric acid solution of composition g / l: Pt-90, Pd-3,5, Ir-3,0, Rh-2,0, Ru-1,5, HCl-182 (5 M), sent for extraction dioctyl sulfoxide (DOS). The ratio of organic to aqueous phases is 4: 1. Platinum and palladium are completely extracted into the organic phase and Ir, Rh, Ru are partially coextracted.

 The organic phase saturated with platinum and palladium is washed from coextracted impurities with a solution of hydrochloric acid with a concentration of 150 g / l (4 M) at a ratio of organic and aqueous phases of 8: 1.

 The washings are combined with the stock solution and sent for extraction.

 The organic phase washed from the impurities of Ir, Rh, and Ru is directed to the re-extraction of platinum. Re-extraction of platinum is carried out with a solution of hydrochloric acid at a concentration of 70 g / l (2 M) with a ratio of organic to aqueous phase of 2: 1.

 The platinum reextract is in contact with the fresh DOSO extractant in the ratio of organic and aqueous phases 1: 5 for deep purification of the platinum reextract from palladium.

 The organic phase containing palladium is combined with the organic phase obtained after processing the DOSO platinum reextract, and sent to the palladium reextraction with 25% ammonia solution.

 The ratio of organic phase to water is 10: 1.

 The recovery of platinum and palladium is 99.5%. The purity of the obtained platinum and palladium products is not less than 99.98%.

 Example 2. The initial hydrochloric acid solution of the composition, g / l: Pt-27, Pd-60, Ir-6, Rh-5, Ru-2, HCl-182 (5M) is sent for extraction with a solution of petroleum sulfoxides (HCO) in kerosene. The ratio of organic and aqueous phases is 4: 1.

 Platinum and palladium are completely extracted into the organic phase and Ir, Rh, Ru are partially coextracted.

 The organic phase is washed from impurities with a solution of hydrochloric acid 150 g / l (4 M) with a ratio of organic and aqueous phases of 6: 1. The washed organic phase is directed to platinum reextraction. Reextraction is carried out with a solution of hydrochloric acid 70 g / l (2 M) with a ratio of organic and aqueous phases of 7: 1.

 The platinum reextract is in contact with fresh HCO at a ratio of organics and aqueous phases of 1: 3.5. The organic phase containing palladium obtained after combining the solutions after re-extraction of platinum and processing of the re-extract of platinum HCO is directed to the re-extraction of palladium with 25% ammonia solution at a 1: 1 ratio of organic to aqueous phases.

 The extraction and purity of the products, as in example 1.

 When carrying out the process in all the claimed ranges of acid concentration in the initial solution, during washing and during platinum re-extraction, the same results were obtained.

Claims (4)

 1. The method of extraction and separation of platinum and palladium from a hydrochloric acid solution, including their extraction and subsequent re-extraction from the organic phase, first platinum, and then palladium, characterized in that the extraction is carried out from a solution containing at least 5 M hydrochloric acid, using as sulfoxide extractant, and platinum re-extraction is carried out with a solution containing 1-4 M hydrochloric acid.  2. The method according to claim 1, characterized in that the organic phase after extraction is washed with a solution of hydrochloric acid with a concentration of 4 to 5 M.  3. The method according to claim 1 or 2, characterized in that the platinum re-extract is treated with the sulfoxide used in the extraction, and the palladium re-extraction is carried out from a mixture of organic phases obtained after the platinum re-extraction and after the platinum re-extraction is treated with the sulfoxide.  4. The method according to claim 1 or 3, characterized in that the re-extraction of palladium is a solution of ammonia.