The method of processing of spent catalysts containing metals of platinum group

 

(57) Abstract:

The invention relates to the metallurgy of noble metals and can be used when extracting platinum group metals from spent catalysts, including automotive, on the basis of the oxides of aluminium, silicon and magnesium, containing platinum or palladium. The technical result is to simplify the hardware design process, reducing the loss of platinum metals, improving the quality of the final product is a concentrate of platinum metals and recyclability of the catalysts based on various modifications of aluminum oxide. The method of processing of spent catalysts containing platinum metal, based on the oxides of aluminium, silicon and magnesium is in the grinding of the catalyst, acid treatment, rihtovanie solid residue with a hydroxide of an alkali metal, sintering, water leaching SPECA and filtering to obtain a concentrate of platinum metals. According to the invention the grinding lead to -3 mm, acid - sulfuric acid solution with a concentration of 2 to 2.5 mol/DM3with the introduction of inorganic reductant, rihtovanie solid residue when the ratio of the alkaline hydroxide is CA - in the presence of an alkaline reagent. The sulfuric acid treatment of the catalyst is carried out at a temperature of 50-90oC for 4-6 h at T : W 1 : (3-5) as an inorganic reductant use of copper compounds (I), for example, copper oxide (I), particle size of 0.5 mm in relation to the platinum group metals 0,2 -0,5 from the stoichiometry of reaction recovery. As a hydroxide of an alkali metal during sintering using sodium hydroxide or potassium hydroxide as the alkaline reagent in aqueous leaching using sodium hydroxide or potassium hydroxide with a concentration of 10-20 g/l, water leaching is carried out at T : W 1 : (3-5) for 1-2 h 6 C.p. f-crystals, 3 tables.

The invention relates to the metallurgy of noble metals and can be used when extracting platinum group metals from spent catalysts, including automotive, on the basis of the oxides of aluminium, silicon and magnesium, containing platinum or palladium.

There is a method of processing waste of platinum-containing catalysts based on alumina by sintering with sodium hydroxide in the recovery environment. Sintering is carried out at a temperature of 900-950oC with the introduction of the carbon. Spec leached with a solution of sulfuric acid in prisutstvie the 2100072 C1 (Omsk state University), 27.12.97).

The disadvantages of the method are its high energy consumption and high consumption of reagents on stage leaching of cake. When using the method for recycling of automotive catalysts containing as the basis magnesium oxide, receive trudnoobrabatyvaemyh concentrate platinum metals of low quality, as magnesium oxide during sintering transformed into an insoluble form, together with the associated oxides of aluminium and silicon. The content of platinum in concentrate does not exceed 20-25%.

There is a method of processing of spent catalysts based on alumina containing platinum group metals, including sintering with caustic soda to convert the aluminum oxide to sodium aluminate. Spec leached with water, with sodium aluminate goes into solution, and the platinum group metals remain in the solid residue. The residue is separated by filtration, treated with hydrochloric acid to remove any remaining impurities, filtered off, washed and dried (see I. N. Malinetskii, L. C. Chugaev. Metallurgy of noble metals. M. metallurgy, 1972, S. 356-357). The resulting concentrate of platinum metals sent for refining.

The disadvantages of the method are Nesbit.to. at the stage of water leaching SPECA possible hydrolysis of sodium aluminate, and the recycling of automotive catalysts concentrate contains trudnoperevarivaema complex compounds of magnesium, aluminum and silicon.

There is a method for processing of spent automotive catalysts based on oxides of aluminum, magnesium, silicon, containing platinum metals, including opening the basics of the catalyst by treatment with a solution of sulfuric acid (34%) in an autoclave at a temperature of 150oC, a pressure of 10 ATM for 90 minutes Before opening the catalyst is subjected to fine grinding (-100 mesh). The base components into solution, and the platinum metals remain in the solid residue. After filtering receive the concentrate of platinum metals (see Precious Metals '89. Ed. by M. C. Jha and S. D. Hill. The Minerals, Metals and Materials Soc., 1988, S. 491-492).

The disadvantages of the method are the need for fine grinding of the starting material (-100 mesh), the complexity of the hardware design, the inevitability of the loss of platinum metals on stage acid treatment, low enriched concentrate and restrictions on modification of aluminum oxide.

The technical result of the claimed invention is the simplification and the congestion without limitation on modifications of aluminum oxide, reduced losses of platinum metals, improving the quality of the final product is a concentrate of platinum metals and selective extraction of magnesium.

This is achieved by a method for processing of spent catalysts containing platinum group metals, on the basis of the oxides of aluminium, silicon and magnesium, which includes grinding, processing of the crushed catalyst sulfuric acid solution, filtering to obtain a concentrate of platinum metal according to the invention the grinding lead to -3 mm, treated with a solution of sulphuric acid is carried out in the presence of inorganic reducing agent, insoluble residue after filtration sitout with alkali metal hydroxide in the ratio of 1: (0,8-1,2) and is sintered at a temperature of 400-700oC for 1-2 hours followed by water leaching SPECA in the presence of an alkaline reagent, while acid treatment catalysts are sulfuric acid solution at T:W 1:(3-5), the temperature of 50-90oC and stirring for 4-6 hours, and as a reductant use of copper compounds (I) of size -0,05 mm in relation to the platinum group metals 0.2 to 0.5 from the stoichiometry of the reduction reaction of platinum metals, as hydroxide y is m leach solution using sodium hydroxide or potassium hydroxide with a concentration of 10-20 g/DM3and water leaching is carried out at T:W 1 :(3-5) for 1-2 hours.

The invention consists in the following.

The claimed combination of features allows you to replace the complicated hardware design pressure way of opening the basics of the catalyst with a solution of sulfuric acid at a more economical way - sintering with the alkaline reagent, and the introduction of pre-treatment of the catalyst with a solution of sulfuric acid eliminates the possibility of formation of resistant forms complex compounds of magnesium, aluminum, silicon at the stage of sintering, and the presence of inorganic reducing agents, compounds of copper (I) prevents the loss of platinum metals when dissolved. In addition, achieves selective extraction of magnesium and platinum group metals. All components of the framework after acid treatment at the stage of sintering turn into water-soluble form, thereby obtaining a concentrate of platinum metals not only with a high degree of enrichment, but also suitable for subsequent refining without additional costs for refractory components.

Sulfuric acid treatment in the presence of a reducing agent eliminates the possibility perehodah processing provides high performance extraction of magnesium and purification from impurities and primary enrichment concentrate.

The introduction of the reductant at the stage acid treatment residue creates in the system redox potential, preventing oxidation and transfer of platinum metals in solution.

During sintering of the solid residue with alkali remaining in it after acid treatment of the oxides of aluminum and silicon is transferred into water-soluble compounds. The declared parameters - temperature 400 - 700oC, the ratio of the alkaline reagent and the solid residue (0,8-1,2):1 and a process time of 1-2 hours to ensure complete opening of the base. Water leaching of SPECA in the presence of an alkaline reagent prevents the hydrolysis of sodium aluminate and thereby provides the most complete transition of aluminum in the solution.

The combination of the claimed methods and modes allows you to get suitable for refining the concentrate with the PGM content of not less than 40%, while the extraction of platinum metals a 99.0-99.4 per cent.

Substantiation of the parameters

The grinding of the catalyst to -3 mm is necessary for its full opening. Acid treatment of the crushed catalyst at a concentration of sulfuric acid of less than 2.0 mol/DM3worsens the conditions of transition in a solution of magnesium and impurity components and reduced the UP> not increase the cleaning efficiency.

The specified temperature acid treatment (50-70oC) intensifies the process of dissolution.

The use of copper oxide (I) as a reducing agent at a given its size and the flow creates a redox potential that prevented platinum metals found in high-level and fine form in the solution.

The decrease of the ratio of alkaline reagent to the solid residue in the mixture is less than 0.8:1 does not provide for a full transition oxides of aluminium and silicon in water-soluble compounds, and an increase of more than 1.2:1 leads to unsustainable consumption of the reagent.

At temperatures below 400oC and time of sintering less than 1 hour does not fully opening the basics, and the temperature increase of more than 700oC and time more than 2 hours does not improve the performance of the autopsy process, but leads to waste of energy.

When the concentration of the alkaline reagent is less than 10 g/DM3at the stage of water leaching possible hydrolysis of sodium aluminate and the incomplete transition in a solution of aluminium, and the concentration is higher than 20 g/DM3not intensifies its dissolution, and the flow rate of the reagent Neratovice, because it creates the conditions most complete leaching of soluble components without irrational increase material flows.

Example

The spent catalyst based on alumina, containing (wt.%): Pd - 1,4; Fe, Ni, Cu and 1.1; SiO2- 17,9; MgO - 5,6; Al2O3- else, particle size 3 mm leached in sulphuric acid with a concentration of 2.0 mol/DM3at a temperature of 70oC T:W 1:4 for 5 h in the presence of copper oxide (I). The copper oxide (I) particle size of 0.05 mm is imposed at the rate of 0.3 from the stoichiometry of the reduction reaction of palladium. After the treatment the pulp was filtered and the residue dried. The solid residue is mixed with sodium hydroxide in the ratio of 1: 1 and is sintered at a temperature of 550oC for 1.5 hours. Spec leached water with the introduction of 15 g/DM3sodium hydroxide at T:W 1:4 for 1.5 hours and then filtered. The residue is dried.

Extraction of palladium in concentrate makes up to 99.2%, and the content of palladium in concentrate - 53%.

The results of the method at other values of the declared parameters are presented in tables (see below).

In table. 1 shows the results of extraction of platinum group metals at the opening of the catalysis is di (I). Sintering was carried out at the ratio of sodium hydroxide with the solid residue in 1:1, a temperature of 500oC, time of 1.5 hours.

Water leaching care was implemented with the introduction of the sodium hydroxide solution with a concentration of 15 g/DM3T:W 1:4, time 1 hour.

In table. 2 results of the extraction of platinum group metals in the catalyst recycling size -3 mm Sintering of the solid residue with sodium hydroxide was carried out in the stated values of the parameters.

The sulfuric acid treatment of the catalyst was carried out with a solution of sulfuric acid in the presence of copper oxide (I) in relation to the platinum group metals of 0.3 from the stoichiometry of reaction, recovery, temperature 70oC T:W 1:4 with stirring. Water leaching SPECA was carried out in the presence of alkali in amount of 15 g/DM3if T:W 1:4, time 1.5 hours

In table. 3 results of the extraction of platinum group metals in the waste catalyst particle size 3 mm with an aqueous leaching SPECA in the presence of sodium hydroxide in the claimed values of the parameters.

The original catalyst was subjected to an acid treatment with sulfuric acid solution with a concentration of 2.0 moles of platinum group 0,3 from the stoichiometry of reaction recovery.

The solid residue was shatavari with sodium hydroxide in the ratio of 1:1 and specaly at a temperature of 600oC.

1. The method of processing of spent catalysts containing platinum metal, based on the oxides of aluminium, silicon and magnesium, comprising grinding the original catalyst, treated with a solution of sulfuric acid, filtering to obtain a concentrate, wherein the grinding is carried out to -3 mm, treated with a solution of sulphuric acid is carried out in the presence of inorganic reducing agent, insoluble residue after filtration sitout with alkali metal hydroxide at a ratio of 1:(0,8-1,2) and is sintered at a temperature of 400-700oC for 1-2 h followed by water leaching in the presence of an alkaline reagent.

2. The method according to p. 1, characterized in that as a hydroxide of an alkali metal during sintering using sodium hydroxide or potassium.

3. The method according to p. 1 or 2, characterized in that as the alkaline reagent in aqueous leaching using sodium hydroxide or potassium hydroxide with a concentration of 10-20 g/DM3.

4. The method according to any of paragraphs. 1-3, characterized in that .as inorganic reductant use of copper compounds (I).

6. The method according to any of paragraphs. 1-5, characterized in that the water leaching is carried out at T:W = 1:(3-5) for 1-2 hours

7. The method according to any of paragraphs. 1-7, characterized in that the acid treatment is carried out with sulfuric acid solution at T:W = 1:(3-5), the temperature of 50-90oC and stirring for 4-6 hours

 

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