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INVENTION
Patent of the Russian Federation RU2138568
METHOD FOR PROCESSING PROCESSED CATALYSTS CONTAINING
METALS OF THE PLATINUM GROUP
The name of the inventor: Godzhiev SE (RU); Kovtun VA (RU); Paretsky VM (RU); Gregory F.Gorbulsky (US); Ari E. Mikhelson (US); Yefim L. Fishkin (US)
The name of the patent owner: Valeriy Paretsky (RU); Yefim L. Fishkin (US)
Address for correspondence: 129515, Moscow, ul.akad.Koroleva 13, GINTSVETMET, Paretsky VM.
Date of commencement of the patent: 1998.07.13
The invention relates to the metallurgy of noble metals and can be used in the recovery of platinum group metals from spent catalysts, including automotive, based on alumina, silicon and magnesium oxides containing platinum or palladium.
The technical result is simplification of the process design, reduction of losses of platinum metals, improvement of the quality of the final product - concentrate of platinum metals and the possibility of processing catalysts based on various modifications of aluminum oxide. The method for processing spent catalysts containing platinum metals based on aluminum, silicon and magnesium oxides consists of grinding the catalyst, acidizing, laminating the solid residue with alkali metal hydroxide, sintering, aqueous leaching of the sinter and filtration to produce a concentrate of platinum metals. According to the invention, grinding is performed up to- 3 mm , acid treatment with a solution of sulfuric acid with a concentration of 2 to 2.5 mol / dm 3 with the introduction of an inorganic reducing agent, solid residue clumping - with an alkali metal hydroxide ratio: a solid residue of 0.8-1.2 , Sintering at a temperature of 400-700 ° C for 1-2 hours , aqueous leaching of the cake in the presence of an alkaline reagent. Sulfuric acid treatment of the catalyst is carried out at a temperature of 50-90 ° C for 4-6 hours at T: G 1: (3-5) , as an inorganic reducing agent, copper (I) compounds, for example copper (I) oxide, , 5 mm in relation to the metals of the platinum group 0.2-0.5 from the stoichiometry of the reduction reaction. As an alkali metal hydroxide, sodium or potassium hydroxide is used for sintering, sodium hydroxide or potassium hydroxide is used as an alkaline reagent in aqueous leaching at a concentration of 10-20 g / l , water leaching is conducted at T: F 1: (3-5) for 1-2 hours
DESCRIPTION OF THE INVENTION
The invention relates to the metallurgy of noble metals and can be used in the recovery of platinum group metals from spent catalysts, including automotive, based on alumina, silicon and magnesium oxides containing platinum or palladium.
A method for processing spent platinum-containing catalysts based on aluminum oxide by sintering with sodium hydroxide in a reducing medium is known. Sintering is carried out at a temperature of 900-950 ° C. with the introduction of carbon. Speck is leached with a solution of sulfuric acid in the presence of aluminum to cement the platinum, which has passed into the solution. Platinum remains in the insoluble residue ( see patent RU 2100072 C1 (Omsk State University), 27.12.97 ).
Disadvantages of the method are its high energy intensity and high consumption of reagents in the leaching stage of the sinter. When using the process for the processing of automotive catalysts containing magnesium oxide as base, a hard-to-concentrate concentrate of low-quality platinum metals is obtained, since magnesium oxide, when sintered, becomes insoluble together with the alumina and silicon oxides bound thereto. The content of platinum in the concentrate does not exceed 20-25% .
A method for processing spent catalysts based on aluminum oxide containing platinum group metals is known, including sintering with caustic soda to convert aluminum oxide to sodium aluminate. Speck is leached with water, while sodium aluminate passes into solution, and the metals of the platinum group remain in the solid residue. The residue is separated by filtration, treated with hydrochloric acid to remove any remaining impurities, filtered, washed and dried ( see I.N. Maslenitsky, L.V. Chugaev, Metallurgy of Noble Metals, M. Metallurgiya, 1972, pp.356-357 ). The obtained concentrate of platinum metals is directed to refining.
The drawbacks of the method are the inevitability of loss of platinum metals at the stage of acid treatment and a low degree of concentration of the concentrate, At the stage of aqueous leaching of the sintering, hydrolysis of sodium aluminate is possible, and when processing automotive catalysts, the concentrate contains difficult-to-work complex compounds of magnesium, aluminum and silicon.
A method for processing spent automotive catalysts based on aluminum , magnesium, silicon oxides containing platinum metals, comprising opening the catalyst base by treatment with a solution of sulfuric acid ( 34% ) in an autoclave at a temperature of 150 ° C , a pressure of 10 atm for 90 minutes is known . Before opening, the catalyst is finely ground ( -100 mesh ). Elements of the base pass into the solution, and the platinum metals remain in the solid residue. After filtration, a concentrate of platinum metals is obtained ( see Precious Metals' 89, Ed. By MC Jha and SD Hill, The Minerals, Metals and Materials Soc., 1988, pp. 491-492 ).
Disadvantages of the method are the need for fine grinding of the starting material ( -100 mesh ), the complexity of the instrumentation, the inevitability of loss of platinum metals in the acid treatment stage, the low degree of concentrate enrichment, and the limitations on the modification of aluminum oxide.
The technical result of the claimed invention is the simplification of the process design of the process, the expansion of raw materials due to the ability to process catalysts without restriction on the modification of aluminum oxide, reducing losses of platinum metals, increasing the quality of the final product, the concentrate of platinum metals and selective magnesium recovery.
This is achieved by the fact that in the process for processing spent catalysts containing platinum group metals based on alumina, silicon and magnesium oxides including grinding, treating the crushed catalyst with sulfuric acid solution, filtering to produce a platinum metal concentrate, according to the invention, grinding is conducted up to- 3 mm , Treatment with a solution of sulfuric acid is carried out in the presence of an inorganic reductant, the insoluble residue after filtration is mixed with an alkali metal hydroxide in a ratio of 1: ( 0.8-1.2 ) and sintered at 400-700 ° C for 1-2 hours followed by Aqueous leaching of the sinter in the presence of an alkaline reagent, wherein the acid treatment of the catalyst is carried out with a solution of sulfuric acid at T: M 1
3-5) , at a temperature of 50-90 ° C and stirring for 4-6 hours , and copper (I) compounds of a size of 0.05 mm are used as the reducing agent in the ratio with metals of the platinum group of 0.2-0.5 of The stoichiometry of the reduction reaction of platinum metals, sodium hydroxide or potassium hydroxide is used as an alkali metal hydroxide during sintering, a solution of sodium or potassium hydroxide with a concentration of 10-20 g / dm 3 is used as an alkaline reagent in aqueous leaching, and aqueous leaching is carried out at T: F 1
3-5) for 1-2 hours .
SUMMARY OF THE INVENTION
The claimed set of characteristics allows replacing the complex autoclave method for opening the catalyst base with a solution of sulfuric acid in a more economical way, sintering with an alkaline reagent, and the introduction of preliminary treatment of the catalyst with a solution of sulfuric acid makes it possible to eliminate the possibility of formation of persistent forms of complex compounds of magnesium, aluminum, Sintering step, and the presence of an inorganic reducing agent, a copper (I) compound, prevents loss of platinum metals upon dissolution. In addition, selective recovery of magnesium and platinum metals is achieved. All components of the base after acid treatment in the sintering stage become water soluble, thereby providing a concentrate of platinum metals, not only with a high degree of enrichment, but also suitable for subsequent refining without additional costs for difficult-to-open components.
Sulfuric acid treatment in the presence of a reducing agent eliminates the possibility of the transition of platinum metals to the solution. Maintaining a sulfuric acid concentration of 2-2.5 mol / dm 3 at the acid treatment stage provides high magnesium recovery and purification from impurities and primary concentrate enrichment.
The introduction of the reducing agent in the acid treatment of the residue creates a redox potential in the system, which prevents oxidation and the transition of platinum metals to the solution.
When the solid residue is sintered with alkali, the oxides of aluminum and silicon that remain in it after acid treatment are converted into water-soluble compounds. The declared parameters are a temperature of 400-700 ° C , the ratio of alkaline reagent and solid residue (0.8-1.2): 1 and the process time of 1-2 hours - ensure the completeness of the opening of the substrate. The aqueous leaching of the sinter in the presence of an alkaline reagent prevents the hydrolysis of sodium aluminate and thus provides the most complete transition of aluminum to the solution.
The combination of the claimed techniques and regimes makes it possible to obtain a concentrate suitable for refining with a content of platinum metals of at least 40% , with the extraction of platinum metals 99.0-99.4% .
JUSTIFICATION OF PARAMETERS
Crushing of the catalyst to - 3 mm is necessary for its full opening. Acid treatment of the crushed catalyst at a sulfuric acid concentration of less than 2.0 mol / dm 3 worsens the conditions for the transition of magnesium and impurity components into the solution and reduces the degree of primary concentration of the concentrate, and an increase in the sulfuric acid concentration of more than 2.5 mol / dm 3 does not improve the purification efficiency.
This temperature regime of acid treatment ( 50-70 o C ) intensifies the dissolution process.
The use of copper (I) oxide as a reducing agent at a given particle size and flow rate creates a redox potential that prevents the transition of platinum metals in highly active and finely dispersed form to the solution.
Reducing the ratio of alkaline reagent to solid residue in a charge of less than 0.8: 1 does not ensure a complete transition of aluminum and silicon oxides to water-soluble compounds, and an increase of more than 1.2: 1 leads to an irrational consumption of the reagent.
At temperatures below 400 ° C and a sintering time of less than 1 hour, the substrate is not completely opened, and an increase in temperature of over 700 ° C and a time of more than 2 hours does not improve the performance of the dissection process, but leads to an overuse of electricity.
At an alkaline reagent concentration of less than 10 g / dm 3, the hydrolysis of sodium aluminate and the incompleteness of the transition to an aluminum solution are possible in the aqueous leaching stage, and a concentration above 20 g / dm 3 does not intensify its dissolution and the reagent consumption is not rational.
The relation T: M 1
3: 5) with sulfuric acid treatment and aqueous leaching is the most technologically feasible, because Creates conditions for the most complete leaching of soluble components without an unreasonable increase in material flows.
Example
Spent catalyst based on alumina containing ( wt.% ):
- the rest, 3 mm in size, is treated with sulfuric acid at a concentration of 2.0 mol / dm 3 at a temperature of 70 ° C., T: F 1: 4 for 5 hours in the presence of copper (I) oxide. Copper oxide (I) of 0.05 mm in size is introduced at a rate of 0.3 from the stoichiometry of the palladium reduction reaction. After finishing the treatment, the pulp is filtered and the residue is dried. The solid residue is mixed with sodium hydroxide in a ratio of 1: 1 and sintered at 550 ° C. for 1.5 hours . Speck is leached with water with 15 g / dm 3 sodium hydroxide at T: F 1: 4 for 1.5 hours and then filtered. The residue is dried.
The extraction of palladium into the concentrate is 99.2% , and the content of palladium in the concentrate is 53% .
The results of the implementation of the method with other values of the claimed parameters are presented in the tables (see the description at the end of the description).
In Table. 1 shows the results of extraction of platinum group metals upon opening of catalysts with a size of 3 mm sulfuric acid solution at the stated values of the parameters in the presence of copper (I) oxide. Sintering was carried out at a ratio of sodium hydroxide to a solid residue of 1: 1 , a temperature of 500 ° C. , and a time of 1.5 hours.
Water leaching of guardianship was carried out with the introduction of a solution of sodium hydroxide at a concentration of 15 g / dm 3 , T: F 1: 4 , time 1 hour .
In Table. 2 shows the results of extraction of platinum group metals during the processing of catalysts with a size of 3 mm . Sintering of the solid residue with sodium hydroxide was carried out in the declared 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 (I) oxide in a ratio with metals of the platinum group of 0.3 from the stoichiometry of the reduction reaction, at a temperature of 70 ° C., T: F 1: 4 with stirring. The water leaching of the cake was carried out in the presence of alkali in an amount of 15 g / dm 3 at T: F 1: 4 , time 1.5 h
In Table. 3 shows the results of extraction of platinum group metals during processing of spent catalysts with a size of 3 mm during aqueous leaching of the sinter in the presence of sodium hydroxide in the declared values of the parameters.
The starting catalyst was acid treated with a solution of sulfuric acid at a concentration of 2.0 mol / dm 3 with stirring, T: F 1: 4 , temperature 70 ° C and introduction of copper (I) oxide in a ratio with metals of the platinum group of 0.3 from the stoichiometry of the reaction Recovery.
The solid residue was sacrificed with sodium hydroxide in a 1: 1 ratio and sintered at a temperature of 600 ° C
CLAIM
Method for processing spent catalysts containing platinum metals based on alumina, silicon and magnesium oxides, comprising grinding the starting catalyst, treating it with a solution of sulfuric acid, filtering to obtain a concentrate, characterized in that grinding is conducted up to- 3 mm , treatment with sulfuric acid solution is carried out in Presence of an inorganic reductant, the insoluble residue after filtration is mixed with an alkali metal hydroxide at a ratio of 1
0.8-1.2) and sintered at a temperature of 400-700 ° C for 1-2 hours , followed by aqueous leaching in the presence of an alkaline reagent. The process according to claim 1, characterized in that sodium hydroxide or potassium hydroxide is used as an alkali metal hydroxide during sintering.
print version
Date of publication 07.11.2006гг
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