RU2306347C1 - Method of processing catalysts containing platinum metals and rhenium on aluminum oxide carriers - Google Patents

Abstract

FIELD: metallurgy of noble metals; refining in processing deactivated catalysts containing platinum metals and rhenium on aluminum oxide carriers.

SUBSTANCE: proposed method includes roasting of catalysts, leaching in sulfuric acid, adding the concentrate of dust of refining electric precipitators into pulp thus obtained in the amount of 30-60 kg/m³, cleaning the solution from platinum metals by carburizing on aluminum powder. After separation of sulfuric acid solution by filtration from indissoluble residue, rhenium is extracted from solution by sorption and indissoluble residue is used for extraction of platinum metals by melting. Amount of platinum metals extracted from starting products into target product is about 95.47%.

EFFECT: facilitated procedure of separation of sulfuric acid solution from indissoluble residue; reduced consumption of filtering materials.

2 cl, 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).

Catalysts containing platinum metals on alumina supports are widely used in the petrochemical, chemical and several other industries. The platinum content in various grades of catalysts varies from 0.05 to 1.0%. In some brands of catalysts along with platinum contains palladium, rhodium, ruthenium, as well as rhenium, molybdenum or nickel.

During operation, the catalysts gradually lose their catalytic activity and enter the metallurgical industry for processing in order to extract valuable components.

A large number of hydro- and pyrometallurgical processes are known for processing deactivated catalysts containing platinum metals [M.A. Meretukov, A.M. Orlov. Metallurgy of precious metals (foreign experience). - M .: Metallurgy, 1990, p. 341-343]. However, the use of these methods for processing catalysts containing rhenium along with platinum metals encounters significant technical difficulties and is associated with large losses of the latter.

Closest to the technical nature of the claimed is a method of processing catalysts containing platinum metals and rhenium on alumina supports, according to which spent catalysts are calcined at a temperature of 500-600 ° C, the calcined product is leached in sulfuric acid. Platinum is isolated from the resulting solution by cementation on aluminum powder, the purified sulfate solution is separated from the insoluble residue, the sulfate solution is sent to extract rhenium by sorption on low-basic anion exchange resin, and the insoluble residue is used to extract platinum [Bukin V.I., Igumnov MS, Safonov V.V., Safonov Vl.V. Recycling of industrial waste and secondary raw materials containing rare, noble and non-ferrous metals. - M.: Publishing. Business Capital, 2002 .-- 224 p. (p. 157-159)]. This method is adopted as a prototype.

The disadvantages of the prototype method include serious difficulties in separating the purified sulfate solution from the insoluble residue due to the formation of colloidal precipitates of platinum and aluminum oxide at the stage of leaching of the catalyst burn in sulfuric acid. Separation of such a system with the necessary completeness into a solution and an insoluble residue either requires special expensive equipment, or, using simple filtration, leads to a large consumption of filter materials and the cost of processing them due to extremely difficult and slow filtration, the need to dilute solutions and rinse the filters.

The proposed method is aimed at obtaining a technical result, which consists in facilitating and accelerating the operation of separating a sulfate solution from an insoluble residue, reducing the consumption of filter materials and the cost of processing them. The achievement of the technical result is ensured by the fact that after leaching the calcined catalyst in sulfuric acid, the dust pulp is added to the resulting pulp of electrostatic precipitators of refining production (in the amount of 30-60 kg / m ³ pulp calculated on the dry weight of the KPI), the resulting mixture is cemented with aluminum powder, then separated sulfate solution from insoluble residue by filtration.

Refined Dust Concentrate (KPI) is an industrial product containing noble metals and also needs to be processed. KPIs are inevitably formed as a result of the aggregate implementation of a complex of various technological operations, accumulated in a dust and gas tunnel and a gas purification system for refineries.

A characteristic feature of KPI is that its base is represented by a large number of different chemical elements and their compounds, mainly ammonium and silver chlorides, volatile non-precious metal chalcogenides, silica, and black carbon. This intermediate product contains from 0.5 to 3% PGM (in total), from 3 to 10% silver.

It is known that the processing of dust flares 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 essence of the proposed method lies in the fact that when KPI is added to the pulp formed during the leaching of the cinder of catalysts in sulfuric acid, the aggregate stability of the entire colloidal system changes. This, in turn, causes such changes in the nature of colloidal sediments that lead to a sharp increase in the ability of the spatial separation of the system into a sulfate solution and an insoluble residue using simple filtration, which is carried out without any difficulties after cementation of the solution from precious metals to aluminum powder.

The achievement of the technical result is ensured when the value of the KPI addition of refining production is from 30 to 60 kg / m ^{3 of} pulp (calculated on the dry weight of the KPI).

When adding less than 30 kg of KPI per 1 m ^{3 of} pulp, the ability of the resulting system to separate into a sulfate solution and insoluble residue by filtration is reduced.

The addition of KPIs in an amount of more than 60 kg / m ^{3 of} pulp is also impractical, since it leads to an unjustified increase in the mass of insoluble residue and a decrease in the efficiency of using filter equipment.

The sulfuric acid solution purified by cementation with aluminum powder (as in the prototype method) is sent to extract rhenium by sorption on a low basic anion exchange resin, and the insoluble residue is used to extract platinum.

Usage example.

50.0 g of the deactivated catalyst on an alumina carrier containing 0.30% platinum and 0.38% rhenium were taken and calcined in an electric furnace in an atmosphere of air at a temperature of 600 ° C for 1 h. The calcined product was pulp in 85 ml of water , 85 ml of sulfuric acid (d = 1.82 g / cm ³ ) was added and kept under stirring at a temperature of 135 ° C for 1 hour, after which it was diluted with water to a volume of 750 ml. To the resulting pulp with stirring and a temperature of 80-90 ° C was added 55.0 g of wet dust concentrate of electrostatic precipitators (KPIs) of refining production (W = 42.8%).

Thus, the estimated dry weight of the KPI additive was 31.5 g per 750 ml of pulp. KPI according to the analysis contained (by dry weight), wt.%: Pt - 0.53; Pd 0.79; Rh 0.03; Ir - 0.01; Ru - 0.04; PGM (in total) - 1.40%; 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%.

0.75 g of aluminum powder was added to the resulting mixture. The cementation process of the resulting mixture was carried out for 1 hour, after which the pulp was filtered using a laboratory vacuum funnel and a paper filter. Filtration proceeded without any complications. The specific filtration rate was 79.8 l / (m ² · h), which is 8-10 times higher than the specific filtration rate when implementing the prototype method (under comparable conditions).

41.0 g of a wet (W = 32%) insoluble residue and 750 ml of a sulfuric acid solution containing 228 mg / L of rhenium, 0.4 mg / L of platinum, 0.5 mg / L of palladium, 2.0 mg / L were obtained. Rhodium, 0.5 mg / L of iridium, 4.0 mg / L of ruthenium, 1.0 mg / L of silver. Thus, about 90% of rhenium from the initial catalysts passed into the solution. The solution was directed to the extraction of rhenium by sorption on low basic anion exchange resin.

The resulting insoluble residue (BUT) was dried in an oven at a temperature of 110 ° C for 3 hours and then used to extract platinum metals from it by concentration-separation melting.

To dry BUT (weight was 27.9 g) fluxes were added (14.0 g of crushed silicate-sodium glass, 5.6 g of soda ash, 5.6 g of calcium oxide) and 2.8 g of carbonic reducing agent - coke. 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 for 45 minutes at a temperature of 1300 ° C. After melting, the crucible was unloaded from the furnace.

After cooling, hardened melting products were removed from the crucible:

- 3.16 g of the target heavy alloy of platinum metals and silver with the following content of the analyzed elements (according to ICP),%: Pt - 9.88; Pd - 7.42; Rh 0.23; Ir 0.08; Ru - 0.25; PGM (in total) - 17.86%; Ag 34.51;

- 3.66 g of matte-like light alloy containing (according to ICP),%: Pt - 0.03; Pd 0.25; Rh - 0.01; Ir 0.007; Ru - 0.04; PGM (in total) - 0.337%; Ag - 18.6;

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

Thus, in the target heavy alloy from the initial poor products - alumina-platinum catalysts and KPIs of refining production, extracted,%: Pt - 98.52; Pd 94.14; Rh 77.89; Ir 77.42; Ru - 62.78. Extracting the amount of PGM amounted to 95.47%. The obtained target heavy alloy of platinum metals is easily crushed into powder and can be processed as a concentrate of refining production.

A matte-like light alloy may be subjected to further recovery of the noble metals using known methods.

The use of the present invention in the processing of catalysts containing platinum metals and rhenium can simplify and significantly accelerate the separation of the sulfuric acid solution from the insoluble residue by filtration, reduce the consumption of filter materials and the cost of processing the resulting intermediate products.

Claims (2)

1. A method of processing catalysts containing platinum metals and rhenium on alumina supports, comprising burning catalysts, leaching the calcined product in sulfuric acid, cementing platinum metals with aluminum powder, separating the resulting pulp into a sulfate solution and insoluble, filtering the residue, extracting rhenium from sulfate solution by sorption on low-basic anion exchange resin, the extraction of platinum metals from an insoluble residue, characterized in that after leaching the calcined product in sulfuric acid in the resulting pulp is added a dust concentrate of electrostatic precipitators of refining production in the amount of 30-60 kg / m ³ pulp and cementation of platinum metals with aluminum powder is carried out from the resulting mixture. 2. The method according to claim 1, characterized in that the platinum metals from the insoluble residue are extracted by the method of concentration-separation melting, for which a charge of the following composition is used,%: insoluble sulfate leach residue 50-60 soda ash 10-15 calcium oxide 5-15 carbonic reducing agent in the form of coke 3-7 silicate sodium glass rest