RU2531333C2 - Method of extraction of platinoids from spent automotive catalysts - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to pyrometallurgy. The spent automotive catalysts milled to obtain the fraction 3-5 mm, the mix material is prepared by agitation of milled catalysts with cuprum or iron-based metal chips and live lime as a fluxing stone, in the arc furnace the accelerant from cuprum or iron-based metal grab iron or metal chips is built-up, mix material is melted in the arc furnace with the heating to the melting temperature, then the heating is performed up to the temperature 1600-1700°C with the equalising at this temperature for a settling-down of drops of the metal phase on the hearth of the arc furnace with obtaining of concentrate of platinoids; dross is drained, and then the concentrate of platinoids is poured.

EFFECT: increase of extraction of platinoids is provided.

Description

The invention relates to the processing of secondary raw materials, in particular to a pyrometallurgical method for processing spent automotive catalysts (OAK) based on honeycomb ceramic blocks consisting of aluminum, silicon and magnesium oxides and containing platinum group metals (PGMs), where PGMs are used in the form of double or triple systems, for example: Pt / Rh; Pd / Rh; Pt / Pd / Rh, with the extraction of the latter.

There is a method of extracting PGM from spent catalysts, including automotive, based on aluminum, silicon and magnesium oxides containing platinum or palladium, which consists in grinding the catalyst, acidizing, blending the solid residue with alkali metal hydroxide, sintering, aqueous leaching of cake and filtering to obtain a platinum metal concentrate (patent RU 2138568 C1, C22B 11/00, 09/27/1999).

The disadvantages of this method:

- the use of expensive, toxic, chemically hazardous reagents;

- receipt of a large amount of hazardous waste;

- the occurrence of problems with the disposal of waste;

- the complexity of waste recovery.

There are also known methods for the extraction of PGMs from spent catalysts by their oxidation with gaseous reagents (oxidative calcination with oxygen, chlorination, fluorination), followed by their separation from the base. In these cases, for example, during chlorination, a high-temperature treatment is carried out until the formation of volatile platinum carbonyl chlorides, which are captured by absorption and emit metal by reductive deposition (JP patent 5414571 from 08.06.79, US patent 4069040 from 17.01.78., US patent 4077800 from 07.03.78 )

The disadvantages of this method:

- highly aggressive gaseous reagents are very dangerous in operation and require the use of expensive equipment;

- compliance with enhanced security measures;

- the need for disposal of toxic compounds.

The claimed invention is directed to the development of a faster, simpler, cheaper and more environmentally friendly way to separate PGM from OAK; Exclusion from the OAK processing process of expensive, toxic, chemically hazardous reagents and their waste products; increasing the concentration of PGM in the metal phase for its subsequent refining; reduction of PGM losses during their extraction from OAK, improving the quality of the final product - metal PGM concentrate.

The method includes melting a mixture consisting of crushed OAK mixed with metal shavings based on copper or iron and quicklime as flux, with the concentration of extracted PGMs in the metal phase on the hearth of the furnace.

The implementation of the OAK processing method is as follows:

- crush OAK to obtain a fraction of 3-5 mm;

- prepare a batch charge, for this crushed OAK is mixed with metal chips based on copper or iron and quicklime as a flux. Metal shavings are introduced into the charge onto certain brands of catalysts. Metal shavings in the charge are necessary for more complete extraction of PGMs from slag melt - drops of molten metal attract microscopic drops of PGMs. The choice of material for metal chips based on copper or iron is made depending on the composition (grade) of OAK;

- melting the charge is carried out in an arc furnace (direct or alternating current).

At the beginning of the process in the arc furnace, the collector is fused from scrap metal or metal chips based on copper or iron. Then, the first portion of the previously prepared mixture is introduced into the furnace. The mixture is introduced evenly into the zone of stable arc burning. After the entire portion of the charge has been introduced, it is completely melted, heated to a temperature of 1600-1700 ° C and a thermal time soaking (TBB) is given at this temperature to precipitate drops of the metal phase formed during the smelting on the bottom of the arc furnace.

After the TVV, the “empty slag” (ie, slag not containing PGM) is poured into metal molds. The metal concentrate remains in the furnace.

Then, a second portion of the charge is introduced onto the liquid metal concentrate and all the above operations of melting, heating, and TBB are repeated. Etc. with the third and subsequent servings. At the same time, the concentration of PGMs in a metal bath is constantly increasing.

The result is a concentrated metal phase with an PGM content of up to 2%, which is poured into special molds. The resulting concentrate ingots go to refining. At refineries, pure PGM is recovered by conventional chemical or electrochemical methods.

"Empty slag" is also processed: crushed; passes magnetic separation to extract possible unorganized leaks of the PGM concentrate together with slag.

Crushed slag can be used as crushed stone for roads.

Claims (1)

A method of extracting platinum group metals from spent automotive catalysts, including grinding these catalysts, mixing with additives, heating to high temperatures, characterized in that the spent automotive catalysts are crushed to obtain a 3-5 mm fraction, a charge is prepared by mixing the crushed spent automotive catalysts with metal shavings based on copper or iron and quicklime as flux are melted in an arc furnace a collector made of scrap metal or and metal chips based on copper or iron, the mixture is melted in an arc furnace with the mixture heated to the melting temperature, then the melt is heated to a temperature of 1600-1700 ° C and thermal exposure is performed at this temperature to precipitate drops of the metal phase on the bottom of the arc furnace to obtain of a platinum group metal concentrate, empty slag is drained from the arc furnace, and then a platinum group metal concentrate is drained.