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DEVICES AND METHODS OF EXTRACTING COLORFUL AND NOBLE METALS
INVENTION
Patent of the Russian Federation RU2180011

METHOD OF PROCESSING THE SCRAP OF ELECTRONIC EQUIPMENT PRODUCTS

The name of the inventor: Sidorenko Yu.A. Efimov VN; Shukhovtsev VI; Moskalev A.V .; Agafonov DA; Yeltsin, S.I.
The name of the patent owner: OJSC "Krasnoyarsk Plant of Non-Ferrous Metals named after VN Gulidov"
Address for correspondence: 660123, Krasnoyarsk, Transport pr-d, 1, OAO Krastsvetmet, Science Department
Date of commencement of the patent: 2000.05.03

The invention relates to metallurgy of metals and can be used in the processing of scrap of electronic products, mainly microelectronic circuits containing gold, silver and platinum group metals. The method involves grinding electronic scrap, magnetic separation, melting of the non-magnetic fraction in a mixture with noble metal slag with concentration of the latter in the resulting heavy alloy. The magnetic fraction of the electron scrap is melted with the addition of silicon, the resulting silicon-containing alloy is then used as a platinum group metal collector. The method allows to reduce the duration of the recovery cycle of precious metals.

DESCRIPTION OF THE INVENTION

The invention relates to the metallurgy of noble metals and can be used in the processing of scrap of electronic products, preferably microelectronic circuits containing gold, silver and platinum group metals (PGM).

Microcircuits are the most common elements of electronic technology and are multi-layered, small-sized devices assembled in plastic or ceramic enclosures. Current leads are usually made of magnetic iron-nickel alloys such as "platinum" or "covar", are coated with a thin layer of gold or silver and are attached to a semiconductor crystal fixed on a substrate of corundum or duralumin. The content of precious metals ( Au, Ag, Pd ) in microcircuits is usually small ( 0.1-1.0% ) and depends on the type of products. The plastic used for manufacturing the chip body contains up to 60-70% of the filler (silica, alumina, talc). Similar to the described device have also transistors, diodes and connectors.

A method for processing scrap of electronic industry products containing gold in the form of coatings on metal parts is known [ I.N. Maslenitsky, L.V. Chugayev, V.F. Borbat and others. Metallurgy of precious metals. Ed. 2, ed. L.V. Chugayeva. - Moscow: Metallurgy, 1987, p.349-350 ]. This method involves selectively dissolving the gold coating in a solvent that is inert to the base material. As a solvent, solutions of thiourea, ammonium thiocyanate or iodine can be used.

The use of an analog method for the processing of microcircuits, transistors and other electronic products containing noble metals, usually on the inner surfaces of products in combination with glass, cermet and plastic, does not allow the transfer of precious metals into the solution with sufficient completeness.

The closest in technical essence to the claimed is the method for processing scrap of electronic products, according to which the electronic scrap is first ground in a hammermill to a particle size of 25.4-6.35 mm, then the ground material is subjected to magnetic separation to obtain a magnetic and non-magnetic fractions that are processed apart. A magnetic fraction containing noble metals on an iron-nickel base is used as a metallurgical reagent-a cementing agent in the process of copper carburizing from its solutions. From the non-magnetic fraction, metal components are isolated as the precious metal concentrate by using electrostatic separation and separation by eddy currents. [ Meretukov MA, Orlov A.M. Metallurgy of precious metals. Foreign experience. - M.: Metallurgy, 1991, p. 308-318 ]. This method is taken as a prototype.

The shortcomings of the prototype method include: the need to use complex expensive equipment, a long duration of the recovery cycle of precious metals, which is facilitated, in particular, by their low content in the target scrap separation products.

The present invention is aimed at obtaining a technical result consisting in increasing the efficiency of the processing of scrap of electronic products, preferably microelectronic circuits, by reducing the duration of the recovery cycle of precious metals.

The technical result is achieved by the fact that in a known method for processing scrap of electronic products, which includes grinding scrap, magnetic separation of the crushed material, separation of its metal part from the non-magnetic fraction as a concentrate of precious metals and using a magnetic fraction as a metallurgical reagent:

- Concentration of precious metals from products of magnetic separation is carried out using melting;

- the non-magnetic fraction is melted in a mixture with noble metal slag and a heavy alloy is extracted from the smelting products, which is a precious metal concentrate;

- the magnetic fraction is fused with silicon as a reagent before use, and the silicon-containing alloy is used as a platinum group metal collector;

- Chopping of scrap chips before magnetic separation is conducted until the size is obtained from minus 1 mm to minus 5 mm .

The essence of the proposed invention is as follows . The presence of nickel in the magnetic fraction makes it possible to use it as a reagent for the preparation of a triple iron-nickel-silicate collector, which, as established by special studies, can be effectively used for the concentration and activation of platinum-group metals in the smelting process of noble metal products.

The use of the "triple" iron-nickel-silicon collector (as well as the "double" nickel-silicon) as a result of dressing the industrial products of noble metals produces a decrease in the melting temperature of the charge, the brittleness of the resulting alloys (which is a prerequisite for grinding the alloys to a powder state), increasing the chemical activity of PGM - To subsequent dissolution by chlorination in a hydrochloric acid medium.

Non-magnetic fraction - shredded plastic and ceramic enclosures of microcircuits. The gold content in this fraction is small and amounts to 200-1500 g / t . The basis of the non-magnetic fraction is ceramics (silica, alumina) and hydrocarbon plastics. The presence of hydrocarbon components in the non-magnetic fraction makes it possible to use it as reagent-reductant in the course of lean remelting of slags. In the process of lethal melting of slag in conjunction with the non-magnetic fraction of microcircuits, the concentration of metallic fusible inclusions (microdroplets) contained in the slag melt increases due to inclusions of copper, gold, silver and other metals from the non-magnetic fraction, which leads to an increase in the coalescence rate of the droplets, and, as The consequence contained in both products is that precious metals are efficiently collected, deposited in the slag melt and form a heavy bottom alloy, the PGM concentrate.

Crushing the old chips before obtaining the specified optimum size allows to provide the necessary and sufficient degree of disclosure of parts made of magnetic iron-nickel alloy from their non-magnetic basis. This enables then, by means of magnetic separation, to effectively separate the ground material into two fractions: magnetic and non-magnetic.

The optimum range of size, to which the chips are crushed before magnetic separation, is determined experimentally. A finer grinding (less than minus 1 mm) is inexpedient, since it requires additional costs, accompanied by increased dust formation with subsequent magnetic separation, but does not lead to an increase in the extraction of magnetic components in the magnetic fraction. Insufficient grinding (with a particle size of more than 5 mm) leads to a deterioration in the magnetic separation - the yield of the magnetic fraction increases, and the concentration of magnetic components in it decreases.

Example 1
On a hammer crusher equipped with a replaceable grating with a mesh size of 2.5 mm to remove fines, 767.5 kg of chips in plastic and ceramic casings were crushed. Grinding was carried out with a continuous removal of a material of minus 2.5 mm in size .

The ground material was subjected to separation into magnetic and non-magnetic fractions on a large-scale magnetic separator. In this case, 211.9 kg of magnetic fraction - contacts of microchips based on the "platinum" alloy and 555.6 kg of non-magnetic fraction were obtained. The content in the magnetic fraction, %: gold - 0,77; Nickel - 35; Iron - 35; Tin - 4,3; Lead - 2.5; Copper - 0.5; Selenium - 1,1. The non-magnetic fraction contained 280.0 g / t gold .

As a result of grinding and magnetic separation of microcircuits, 91.2% of gold was extracted into the magnetic fraction. The degree of enrichment of the magnetic fraction in gold was 3.35 .

The non-magnetic fraction of the microcircuits was further processed by joint depletion melting with noble metal waste products (as a reducing additive). For melting we used a charge of the following composition, %: nonmagnetic fraction - 15, lime - 15, the rest - slag of noble metals production based on sodium, calcium and iron silicates.

Four meltings were carried out in a fuel-reflecting furnace. For each melting, 140 kg of non-magnetic fraction of microcircuits were added to the charge. All the slags obtained in the smelting are referred to the category of conditionally salvage by results of testing and analysis. The residual gold content in the slag varied from 3.0 to 3.6 g / t . The products of the smelting were merged from the furnace into cast iron buckets-settlers, from which, after cooling, bottom heavy alloys were separated at the natural interfaces. Heavy alloys in their composition and technological properties were classified as a concentrate of the production of precious metals.

Thus, at the melting stage, almost complete gold recovery from the non-magnetic fraction of the chips to the bottom heavy alloy, the concentrate of precious metals, was achieved, which was further processed using known methods.

The magnetic fraction of the microcircuits ( 211.9 kg ) was mixed with 85 kg of silicon, the mixture was loaded into an electric arc furnace. A top flux, consisting of soda ash, silicate glass, lime and a reducing agent, was loaded from above. The charge had the following composition, % :

Magnetic fraction of microcircuits - 48

Silicon - 16

Calcined soda - 10

Glass - 15

Lime - 8

Coke - 3

The furnace was turned on for heating and melted the loaded materials.

Draining of the melting products was carried out in a cast-iron ladle-settler.

After cooling, the casting of the nickel-silica-containing alloy was separated from the slag. 280 kg of iron-silicon-containing alloy were obtained, which was crushed and then used as a collector reagent when melting industrial products containing noble metals.

The products obtained were successfully processed by known methods.

CLAIM

  1. A method for processing scrap of electronic products, preferably microelectronic circuits containing noble metals, comprising grinding the scrap, magnetic separation of the crushed material, separating its metal part from the non-magnetic fraction as a noble metal concentrate, and using a magnetic fraction as a metallurgical reagent, characterized in that The concentration of noble metals from the products of magnetic separation is carried out using melting, the non-magnetic fraction is melted in admixture with the noble metal slag, and the heavy alloy, which is a noble metal concentrate, is separated from the smelting products and the magnetic fraction is fused with silicon as a reagent and the silicon-containing alloy is used As a collector of platinum group metals.

  2. A method according to claim 1, characterized in that grinding the scrap of microcircuits before the magnetic separation is conducted until the size is obtained from minus 1 mm to minus 5 mm .

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Date of publication 05.12.2006гг