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INVENTION
Russian Federation Patent RU2103396

METHOD FOR PROCESSING SOLUTIONS-middling refining production of platinum group metals

METHOD FOR PROCESSING SOLUTIONS-middling refining production of platinum group metals

Name of the inventor: Nasonova Valery A.; Sidorenko Yuri Alexandrovich
The name of the patentee: Nasonova Valery A.; Sidorenko Yuri Alexandrovich
Address for correspondence:
Starting date of the patent: 1997.01.29

A method of processing solutions - industrial products refinery production relates to metallurgy of precious metals. It can be used in the refinery production of platinum group metals having simultaneously acting receiving redistributions of palladium and rhodium. The method involves the use of a by-product of producing palladium tetraamminpalladohlorida solution - the mother liquor from the precipitation palladozammine PZA for reagent replacement of ammonium chloride during the deposition of ammonium, sodium geksanitrita rhodium in the rhodium refining. Substitute ammonium chloride solution obtained by treating the mother liquor from the precipitation with ammonia palladozammine until a pH in the range from 1 to 5, separating the precipitate and optionally salts evaporating the filtrate. Replacing commercial ammonium chloride solution in the preparation of rhodium - middling refining does not degrade the quality of commercial products.

DESCRIPTION OF THE INVENTION

A method of processing solutions - middlings refining industry relates to the field of metallurgy, in particular precious metals. The method may be used in the refinery production of platinum group metals (PGMs) having simultaneously acting receiving redivisions palladium and rhodium.

Technological schemes of refining platinum group metals (PGM) operations include production and processing of various solutions - industrial products of refined PGM production from raw material containing palladium and rhodium, are the next two.

1. On receipt redistribution rhodium - solution containing sodium rhodium in the form of rhodium geksanitrita Na 3 Rh (NO 2).

2. On receipt redistribution palladium - solution containing water-soluble palladium salt - tetramminpalladohlorid (NH 3)4 PdCl 4.

Processing of these two kinds of solutions according to the literature Metallurgy noble metals. / Ed. Chugaeva LV - M.1987 (p 408-415.) Comprises recovering the solid form of compounds which can be obtained from purified single platinum group metals.

As deposited forms (compounds) is used:

to isolate palladozammine palladium (PZA) - (NH 3)2 PdCl 2, as precipitant agent SHA uses hydrochloric acid [str.415]

to separate rhodium - hexanitro sodium ammonium rhodium (rhodium ENG) - (NH 4)2 NaRh (NO 2)6, as a precipitating reagent used ENG rhodium ammonium chloride (s.412).

The mother liquors from the precipitation and SHA ENG rhodium are additional recovery stage residual PGM using non-precious elements cementation process (s.415).

This method of processing solutions, middlings refining industry is the most similar to the claimed.

The disadvantages of the prototype method of processing varieties of refining industry solutions are:

  • high consumption of ammonium chloride, a reagent in the deposition ENG rhodium;
  • formation on the redistribution of palladium and rhodium obtaining a large amount of mother liquors subjected cementation;
  • the formation of a large amount of wastes, which is irrevocably lost a certain amount of PGM and ammonium chloride.

The alleged invention is directed to the solution of problems reduce consumption ammonium chloride, reducing the formation of effluent and reduce PGM losses.

The problem is solved in that the acidic mother liquor resulting from the precipitation palladozammine tetramminpalladohlorida solution neutralizes ammonia until a PH within 1 - 5, the neutralized solution is filtered off from the precipitate, the filtrate is used as ammonium chloride during the deposition of rhodium ENG.

SUMMARY alleged invention is as follows.

During deposition of the solution palladozammine tetramminpalladohlorida treatment with hydrochloric acid in the mother liquor of ammonium chloride generated by the reaction:

[Pd (NH 3)4] Cl 2 + HCl = (NH 3)2 Cl 2 Pd + 2 NH 4 Cl. (1)

Thus in the process of refining formed palladium solution containing a reagent required for use in rhodium precipitation. However, this solution further comprises ammonium chloride, hydrochloric acid and further because precipitation and completeness of the required purity palladozammine provided tetramminpalladohlorida solution of hydrochloric acid using an excess over stoichiometry of reaction (1). According to experimental studies, because of the presence in the acidic mother liquor PZA hydrochloric acid, compounds of platinum and palladium, and a base element, its use as a reagent to precipitate ENG would lead to a decrease in the extraction of rhodium in the sediment contamination obtained rhodium salt impurities.

Introduction of the invention additional processing operations PZA mother liquor ammonia to establish WP ranging from 1 to 5 and filtering the separated precipitate can:

neutralize hydrochloric acid when the solution while increasing the concentration of ammonium chloride,

allocate a significant portion of platinum, palladium and a number of base elements in the sediment, and impurities remaining in the filtrate is kept in the form of such complexes are not coprecipitated with ENG.

The increase in the neutralized solution of ammonium chloride concentration is due to the reaction:

HCl + NH 3 = NH 4 Cl. (2).

Base metals by neutralizing the acidic mother PZA until a PH in the range of 1-5 falls hydroxides in the precipitate with palladium deposited predominantly in the form of compounds such hlorammiachnyh (NH3) 2 PdCl2, and platinum, apparently as hlorammoniynyh compounds.

Proposed optimal pH range of values ​​from the viewpoints of purity rhodium obtained from the ENG salts in subsequent stages of processing, and saving and ammonia and reagents required for recycling the mother liquors from precipitation ENG.

The lower limit of PH provides extraction of rhodium to increase to 80.3 ENG (experience without neutralization) to more than 99.6% at a minimum flow of ammonia to neutralize (Table. 2).

Increasing the pH in the range from 1 to 3 - 5, as shown in Table. 2, reduces the residual content of rhodium in the mother solution ENG, and a certain increase in the content of ammonium chloride filtrate neutralized PZA mother solution. The latter enables you to share with the solution - middling palladium refining recycle somewhat larger amount of the solution - refining middlings rhodium.

Increasing the PH in the range 1 - 5 does not contribute to deterioration of rhodium obtained from the ENG.

PH Increase of more than 5 is undesirable, since residual platinum in the filtrate turns to form amminokompleksov that promotes the final stages of refining rhodium increase in platinum content of refined rhodium. Moreover, the concentration of ammonium chloride in the filtrate after neutralization PZA mother solution is not increased, therefore, ammonia is consumed useless.

In case of need to increase the concentration of ammonium chloride in the filtrate solution is neutralized it can evaporate. The most expedient fold reduction in volume of the solution by evaporation is in the range 1.5-2. As shown for production tests using deposition ENG filtrate evaporated, evaporation, cooling and subsequent filtration followed by isolation of the precipitate and an additional amount of platinum and palladium, which improves the quality and also improves rhodium recoveries in the other respective commodity products IPY.

Examples of the method

Examples 1. The initial products have typical refinery production of PGM solutions tetramminpalladohlorida and nitrokompleksov solution containing sodium geksanitrorodiat. Tetramminpalladohlorida PH of the solution was about 9.0, PH, containing sodium geksanitrorodiat solution - about 5.0. The chemical composition of combined solutions is given in Table 1 below.

Tetramminpalladohlorida solution was treated (titrated) hydrochloric acid to control the precipitation of completeness and completeness palladozammine transfers impurities dissolved masterbatch base elements. The completeness of the precipitation PZA tried to stop the sludge discharge. The completeness of the translation in the mother liquor of base elements is determined according to X-ray analysis. The completeness of the precipitation with a minimum content of impurities in the SHA-precious elements was recorded when the PH -0.35. Further surging hydrochloric acid did not increase the amount of sediment and PZA did not increase the content of the mother liquor PZA base elements. PZA precipitate separated from the mother solution by filtration. The mother liquor was cooled to room temperature and filtered again precipitated palladozammine slurry.

The cooled filtrate mother PZA solution had a density of 1.061 g / cm 3, pH -0.35 and contained, in g / l: 130.8 NH 4 Cl; 43.5 free HCl; 0.108 Pt; 0.448 Pd; 0.010 Rh; 0.004 Ru; traces Ir, Au and Ag; 0.267 Cu; 0.246 Se; 0.027 Sb; 0.008 Ni.

Equal volumes of the acidic mother liquor (filtrate) was neutralized with ammonia water until a pH of different values in the range from 1 to 7. (Ammonia water was 0b905 density g / cm 3 and contained 231.9 g / L NH 3). 5 received sample solutions containing ammonium chloride, having a pH of 1 to 7.

In the neutralization of acidic mother liquor in a small amount (in the form of slurry) formed precipitates contents mixed salts of platinum and palladium. The neutralized solution was filtered again precipitated from the slurry.

All filtrates were neutralized PZA mother liquors contain approximately equal content, in g / l: 0.087 Pt; 0.251 Pd; 0,007 Rh; 0,003 Ru; traces Ir, Au and Ag; 0.242 Cu; 0,240 Se; 0.023 Sb; 0.008 Ni.

Preparation of the samples after neutralization of the mother liquors with different PZA ph values ​​in the range from 1 to 7 and the source itself and the mother acidic solution having a PH -0.35, was used as a solution of ammonium chloride to precipitate ammonium sodium geksanitrita (ENG) rhodium from solution nitrated IPY, the composition of which is shown in the Table. 1.

For this purpose, the mother liquors from PZA mixed with approximately five times the volume of solution nitrokompleksov PGM hexanitro containing rhodium, the reaction mass was transferred within one hour, after which the separated salt is filtered off. The results showed that in all cases the precipitate was submitted salt (NH 4)2 NaRh (NO 2)6 - ENG rhodium.

Data on the residual content of rhodium in the extraction of mother liquors and to its salt, and the total content of certain impurities in ENG rhodium (as a percentage relative to rhodium content) shown in Table. 2. As can be seen from the above data, the use of rhodium to precipitate ENG not acidic, and pre-neutralized with ammonia water stock solutions can improve the extraction of rhodium in the salt with 80.3 to 99.7 - 99.8%. Simultaneously, the reduced impurity content and rhodium with ENG 16.28 to 12.68 - 14.72% (1.5 - 3.6%).

Indicators deposition of rhodium ENG nitrated filtrates solution obtained from the mother liquor from SHA, it was no worse than using pure ammonium chloride purchased.

ENG obtained samples were processed to obtain rhodium by known techniques, including dissolution in hydrochloric acid, extraction purification and electrolysis of the chloride solution. Required in accordance with GOST 12342-81, the purity of the metal reached during use as ammonium chloride to precipitate ENG neutralized samples of uterine PZA having in the range of 1 to 5. A sample of rhodium produced using ENG during deposition as ammonium chloride mother PZA solution having PH 7, characterized by a high content of platinum.

The mother liquors from the precipitation were recycled ENG existing technology, the process consisting of iron cementation PGM not observed with any process complications.

Example 2. During production tests, which lasted from May to December 1997, the mother liquors from the precipitation of solutions PZA tetramminpalladohlorida neutralized with ammonia water until a PH 4.5-5, the separated salt was filtered off.

Salts weight 75.3 kg containing 3.61% Pt and 23.87% of palladium were processed by the existing technology in the shop of platinum and palladium refining to produce a refined metals.

The filtrates were neutralized solution had a density of 1.02 to 1.06 g / cm 3 and contained ammonium chloride, from 50 to 165 g / l. This filtrate was concentrated in vakuumvyparnom unit until evaporated solution density 1.075 - 1.085 g / cm 3. The evaporated solution is advocated in the collection tank. The pooled evaporated solution used for the deposition of ENG nitrite solutions containing rhodium hexanitro.

During the test team at the bottom of the container formed pellet weighing about 20 kg. The precipitate containing,%: platinum - palladium and 7.8 - 22.0 passed the shop refining of platinum and palladium.

During production testing of co-processing solutions - industrial products refining of palladium and rhodium obtained 14 samples of rhodium. All 14 samples met the requirements of GOST 12342-81 (refined rhodium powder).

As can be seen from Example 2 the proposed method of co-processing solutions-refining middlings palladium and rhodium allows you to:

  • avoid spending purchased ammonium chloride at a concentration of rhodium in ENG;
  • reduce output mother liquors refining industry;
  • loops back into the refining of platinum and palladium on an abbreviated circuit an additional amount of these metals.

Replacement of purchased ammonium chloride solution in the preparation of the rhodium-refining middlings does not degrade the quality of commercial products.

CLAIM

1. A method of processing solutions, industrial products refinery production of platinum group metals, including palladium precipitation from solution in the form tetraamminpalladohlorida palladozammine (SHA) with hydrochloric acid, precipitation of rhodium from a solution of its sodium geksanitrita ammonium chloride in the form of ammonium, sodium geksanitrita (ENG) rhodium separation of precipitation SHA and ENG rhodium filtration, additional recovery of noble metals from the mother liquors refining PGM methods carburizing-precious elements, characterized in that the mother liquor from the precipitation palladozammine neutralized with ammonia until a pH in the range from 1 to 5, the neutralized solution is filtered off from the precipitate, and used as a chloride during the deposition of ammonium ENG rhodium.

2. The method of claim. 1, characterized in that the neutralized mother liquor from the precipitation before use SHA evaporated The evaporated solution was further cooled and the precipitate was separated.

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Publication date 14.03.2007gg