The method of extracting platinum group metals from automobile catalysts

 

(57) Abstract:

A method for extracting amounts of precious metals from scrap scrap catalytic converters. It provides for the transfer of platinum metals in water-soluble state by pre-wetting the catalyst with hydrochloric acid to further oxidative dissolution carried out by a known oxidizing agents such as nitric acid or hydrogen peroxide solution. The process is conducted under heating for continuous circulation steam-leach mixture. The method is quite simple and allows you to engage in the recycling of catalysts with different combination of platinum metals at low reagent cost reduction of losses recoverable metals. 2 C. p. F.-ly.

The invention relates to the field of metallurgy of platinum metals, using as a secondary source of technogenic raw materials, namely scrap automotive exhaust catalysts, where the platinum group metals are used as double or triple systems, such as Pt/Rh, Pd/Rh, Pt/Pd/Rh deposited on a honeycomb blocks, made of cordierite.

Known methods of removing the catalytic components of the platinum group metals by them about the Institute 54-14571 from 08.06.79, U.S. patent 4069040 from 17.01.78, U.S. patent 4077800 from 07.03.78, the applicant Czechoslovakia, Precious Metals 89. Proc. Int. Symp. TMS Annu. Meet., Las Vegas, 483-501] their subsequent separation from the basics. In these cases, such as chlorination, conduct heat treatment prior to the formation of volatile carbonylchloride platinum, which trap absorption and produce metal recovery deposition. Considering the detailed information about the modes of execution of these processes using gaseous oxidants, it is fair to say that they are not quite suitable for processing catalysts-converters of motor fuels. Highly aggressive gaseous reagents is very dangerous in the work and require the use of expensive equipment, compliance with the heightened security, the need for strict disposal of toxic compounds.

Widely presents the methods of extraction of precious metals by oxidation and leaching liquid solvents, such as Royal vodka, nitric acid, a mixture of hydrochloric acid and hydrogen peroxide, chlorine solutions in acids, hypochlorites [Precious and Rare Metal Technol., Proc Symp. Precious and Rare Metals Albuguergue, N. M., Apr. 6-8, 1988./Amsterdam etc., 1989. -P. 345-363, Precious Metals 89. Proc. Int. Svmp. IMS Annu Meet., Las Vegas, Nev, Febr. 27 - March 2, 1989. - Warrendale (Pa), 1989. - p. 483-501, ncacii for a certain type of raw material at a sufficiently low degree of extraction of valuable components. In this case, as a rule, these processes are characterized by complex hardware and technological design, multistage and power consuming.

Closest to the claimed method is leaching of precious metals oxidizing liquid solutions or mixtures, for example the Royal vodka [Thematic review. The extraction of valuable metals from used heterogeneous catalysts. Tsniiteneftehim, M., 1988, S. 29]. Despite the cheapness of the used acids and tional work with Imperial vodka in refining industries, including subsequent gas cleaning, this method is not devoid of significant drawbacks when it is used for recycling of autocatalysts. The presence of blocks cell catalysts-catalysts exhaust engines sublayer of the active aluminum oxide, to which are applied the catalytic elements, determines the difficulty of the complete removal of these noble metals. Liquid-phase leaching due to high values of the surface gamma-aluminum oxide (up to 200 m2/g) always occur two competitive processes: the desorption of the compounds of the platinum metals in solution with the catalyst surface and the reverse sorption on it. It is a reversible equilibrium for its sits removal of metals. The latter fact also leads to the inevitable reagent and energy costs due to the need to process large volumes of low concentration of valuable components. These shortcomings, in the end, determine the high irreversible loss of recoverable metals.

The main objective of the present invention, the solution of which leads to the technical result is the realization of the leaching process, so that constantly changing the concentration of the oxidized metal in the direction of a solution to reduce losses recoverable metals.

The technical result is achieved by a method of extracting platinum group metals from automobile catalysts, including the dissolution of acid-oxidizing mixture according to the invention before the dissolution is carried out wetting the catalyst with an aqueous solution of hydrochloric acid in the ratio of Hcl:H2O=1: 1-5, dissolution of lead followed by heating with the addition of oxidants during boiling in pairs oxidizing reagents, and after washing the precipitate with water from the resulting solution precipitated metals by cementation in the bulk concentrate.

In addition, the dissolution is carried out in dependence on the composition of the raw material from IP is and, as well as the dissolution is carried out in a closed cycle by evaporation and condensation.

Known acid mixture, oxidizing the platinum metals, is used as a liquid and as a vapor. It is translated into a gaseous state removes diffusion problems contact of the reactants with the catalyst metals and ensures completeness of their translation into the solution. For this catalyst blocks are loaded into the reactor at a special slatted shelf, irrigate previously prepared solution of hydrochloric acid in the role and complexing agents and impregnating solution. Its volume is adjusted so that the catalyst is always located above the liquid level. Then turn on the electrical circuit of the heating of the reactor and the reaction liquid is brought to a boil. The process is conducted for a certain period of time for which there is repeated circulation of the vapor oxidizer in the channels and pores of the catalyst and the subsequent discharge of the condensate. The role of the condenser myself to the blocks, until then, until it reaches thermal equilibrium. Upon completion of this stage the resulting solution is directed to filtration, and the catalyst washed with water and prambody about the land of cerium from the resulting solution are known ways.

Thus, the main feature of the proposed method is the use of standard oxidizing mixtures, taking into account the chemical activity of the metal included in the composition of the catalyst in the vapor and liquid States. This allows not only to increase the penetrating ability of the gas mixture, but also to carry out repeated washing of fine particles of platinum metals are always "fresh" solution. Another difference lies in the strict dosage of oxidant, for example, nitric acid and the use of "depleted" NGO3Aqua Regia, sufficient only for the dissolution of the target metals and other impurities formed during operation of the unit. The implementation of these signs is possible because of work on the principle of the closed cycle: evaporation-condensation-wash. The technical result of the invention is achieved by special design of the reactor to obtain the solution, which is a modified column, where the role of reflux plates perform the channels of the blocks of the catalyst. Partly in essence, it reminds modified to the specific conditions of the task to conventional Soxhlet extractions used in organic chemistry d is, the main consequence in determining the merits of the proposed method is the high degree of extraction in a solution of platinum group metals, to obtain solutions with high concentration, low consumption of reagents in comparison with other peers. The inventive method is General, because it allows not only to engage in processing block catalysts with any combination of noble metals, but along the way to highlight the cerium included in these compositions to reduce the coefficient of thermal expansion. The calculated dosage quantities of highly aggressive oxidants dramatically reduces the load on the treatment system and can successfully solve the environmental problems of production in the form of gaseous emissions and drain solutions.

Example 1

The spent catalyst with a car "Mercedes-Benz" weight 1.2 kg has as catalytic metals platinum and rhodium, the residual content of 0.12 and 0.008 wt.% respectively. Due to the small amounts of carbon, not more than 2.2 wt.%, advance preparation by burning is not carried out. The catalyst is placed in a reactor made of PTFE, dipped in an aqueous solution of Hcl (1:1) in the amount of 260 ml (25% of the initial mass of the cat is sledovatelno enter 60 ml of concentrated NGO3and in parts 150 ml of 30% hydrogen peroxide solution. The leaching process continued for 1.5 hours Then heat is removed and the catalyst is washed with distilled water in the ratio of W:t, as 2:1. From the main solution, combined with Promode, precipitated collective platinum-rhodium concentrate cementation aluminum powder. Through the extraction of metals in concentrate amounts to 98.6% for platinum and 94.8% rhodium.

Example 2

Palladium-rhodium catalyst car "Volvo" according to chemical analysis contains 0.08 wt.% palladium and 0.006 wt.% rhodium. In addition, the catalyst contains significant deposits of pyrocarbon, mass fraction which is 8.7 wt.%. Due to the high content of carbon black prior to the recycling process, the catalyst is subjected to preliminary firing at a temperature of 540oC for 45 minutes Subsequent impregnation of the cooled catalyst is carried out with a solution by mixing 46 ml of Hcl conc. and 230 ml of N2O. After making 184 ml of a 30% aqueous solution of N2ABOUT2the reaction mixture of a total number of 460 ml is placed on the heating. Thermal processing after the start of boiling should be performed within 1 h, the Output of refined metals 99.5% purity stood the truck "Honda" is composed of 0.04% of platinum, 0,06% palladium 0,007% rhodium and 1.4% of cerium. The catalyst is poured on cold 250 ml aqueous Hcl (1:1). After reaching the boiling temperature is consistently treated with a solution of Aqua Regia, followed by the introduction of hydrogen peroxide under the conditions of example 1. As a result of further processing total extraction of refined metals to the original content is platinum 0,3878 g (98,0%), palladium 0,5831 g (98.2 per cent) and rhodium 0,0653 g (94,1%).

Thus laboratory and pilot plant testing process chain processing catalysts-catalysts exhaust of motor fuels from their leaching to produce a marketable metal mobiles platinum metals can significantly reduce the cost of reagents and reduce costs for gas treatment. In addition, it is possible to reuse the cordierite - valuable material carrier of the catalyst for production of new units-converters.

1. The method of extracting platinum group metals from automobile catalysts, including the dissolution of acid-oxidizing mixture, characterized in that before the dissolution is carried out wetting the catalyst with an aqueous solution of hydrochloric acid in the ratio of HCl:N

2. The method according to p. 1, wherein the dissolution is carried out in dependence on the composition of the raw materials used as oxidant concentrated nitric acid and/or a 30% solution of hydrogen peroxide.

3. The method according to p. 1, wherein the dissolution is carried out in a closed cycle by evaporation and condensation.

 

Same patents:
The invention relates to a cleaning method of a slag generated in an electric furnace in metallurgical processes with non-ferrous metals, in particular, the method relates to a semi-continuous method of cleaning

The invention relates to ferrous metallurgy and can be used in the production of magnesium and chlorine by electrolysis of anhydrous chlorides

The invention relates to powder metallurgy, to a device for the production of fine metal powders by condensation from the vapor phase

The invention relates to the field of metallurgy of non-ferrous metals, more specifically to the field of obtaining gold and silver from clay-salt sludge generated by the processing of chloride raw material alkali and alkaline earth metals, mainly sylvinite, carnallite and halite

The invention relates to ferrous metallurgy, in particular to the extraction of lead from secondary raw materials, and can be used in the processing of waste resource rechargeable batteries
The invention relates to ferrous and nonferrous metallurgy, in particular to the field of processing of toxins and can be used to extract metals and sand from the waste
The invention relates to ferrous and nonferrous metallurgy, in particular to the field of processing of toxins and can be used to extract metals and sand from the waste
The invention relates to the utilization of granulated slag and can be used for extraction of Nickel, cobalt and other valuable components from granulated slag dump Nickel production, as well as in the production of building materials

The invention relates to ferrous metallurgy and can be used to produce castings of pig iron

The invention relates to the extraction and selective extraction of metal components, such as uranium, thorium, scandium and zirconium, from the source material, which consists of these components
The invention relates to technology radiochemical processing of structural materials of a fusion reactor

The invention relates to technology for processing titanosilicates raw materials, in particular to the decomposition stanovova concentrate

The invention relates to the extraction of metals from ores, in particular to the processing of uranium ores

The invention relates to the preparation of iron ore concentrates for metallurgical treatment by improving their quality due to the removal of undesirable impurities contained in concentrates, primarily phosphorus

The invention relates to chemical technology of obtaining compounds of rare metals

The invention relates to a process for recovering valuable metals from metal-containing materials, such as ore, ore sludge and slag

The invention relates to the field of metallurgy of non-ferrous metals, more specifically to the field of obtaining gold and silver from clay-salt sludge generated by the processing of chloride raw material alkali and alkaline earth metals, mainly sylvinite, carnallite and halite
Up!