RU2323065C2 - Hard-alloy articles production method of lumpy waste of cobalt-containing hard alloys - Google Patents

Abstract

FIELD: powder metallurgy, namely production of hard alloys, possibly manufacture of wear resistant hard-alloy articles of waste material of hard alloys.

SUBSTANCE: method comprises steps of preparing charge by breaking lumpy waste material containing 4, 6, 8 or 10 mass % of cobalt; screening it for separating fraction with size 60- 120 micrometers and subjecting to electromagnetic concentration; adding to concentrated powder 20 - 30 mass% of hard-alloy charge with the same content of cobalt as waste material or adding 20 -30 mass % of hard-alloy charge having cobalt content exceeding by 2 mass% or 4 mass% cobalt content of waste material while adding the same content of cobalt to concentrated powder. Fine grinding is realized in vibration grinding mill till mean size of particles 3 - 4 micrometers. The blanks are pressed, dried and sintered in vacuum at temperature 1390 - 1420°C.

EFFECT: high hardness, improved bending strength, decreased cost price of produced hard alloy article.

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Description

The invention relates to the production of hard alloys and can be used mainly for re-production of wear-resistant carbide products from solid alloy waste.

There are a number of methods for processing solid alloy waste, the main of which is the method of chemical regeneration. Its preliminary stage is the enrichment of waste [Collection and processing of solid alloy waste / N.A. Kudrya, G.V. Lindo, Yu.N. Yurkevich et al. - M .: Mintsvetmet. - 1977. - 44 s]. The mixture enriched mechanically contains a significant amount of iron, which is removed by treatment in sulfuric acid, converting it into a solution. The obtained tungsten concentrate contains up to 60% tungsten and is then subjected to heat treatment - oxidation of the concentrate in air at 800-900 ° С, reduction of the oxidized product with hydrogen at 700-1100 ° С to obtain metallic tungsten and cobalt, carbidization of the reduced product to obtain a WC- mixture So [Tarakanov B.M., Balakir E.A., Denisov NB Oxidation of crushed solid alloy wastes in a fluidized (filtering) layer // Sat. Proceedings of VNIITS. - M. - 1991. - S. 92-97].

The known method [Zelikman A.N., Kasparova T.V., Binder S.I. Preparation of hard alloys from regenerated WC-Co mixtures obtained from lumpy wastes using the “zinc method” // Tsv. metals. - 1993, No. 1. - S.47-49], according to which lump waste (waste rolls, dies, dies) is proposed to recycle the so-called the zinc method, based on the destruction of the hard alloy and the extraction of cobalt into a zinc melt with its subsequent distillation.

In Russian patent No. 2157741, it is proposed to anneal carbide scrap in a protective atmosphere or vacuum at a temperature above 2000 ° C, crush it, grind it to a fraction of ≤40 μm, and the annealing temperature is determined depending on the cobalt content. The method provides for obtaining commodity mixtures suitable for the manufacture of high-quality carbide products.

To extract tungsten and cobalt from solid alloy waste in the form of scrap, as well as powdery and dusty waste (Russian patent No. 2190678), the feedstock is treated with a solution of sodium hypochlorite in an alkaline medium, followed by their separation in a solution (filtrate) and solid sediment. This technical solution avoids energy, resource and time costs associated with their grinding or separation into fractions.

The closest in technical essence to the claimed invention is the method proposed in the patent of Russia No. 2170646, published July 20, 2001 (prototype). The method includes heat treatment of lumpy waste of hard alloys by heating and cooling in an aqueous solution of sodium chloride, followed by mechanical grinding in a jaw crusher or in an inertial cone crusher. The method allows to obtain powders of various fractional composition and sintered hard alloys from them according to traditional technology, including pressing the blanks, their drying and sintering at 1390-1420 ° C.

The disadvantages of this method include the need for preliminary heat treatment, which increases the cost and can lead to the oxidation of powders.

The objective of the proposed technical solution is to reduce the cost of carbide products while maintaining a high level of physical and mechanical properties and improving environmental safety.

The solution to this problem is provided by the fact that in the method of manufacturing carbide products from lumpy waste of hard alloys containing cobalt, including the preparation of a mixture by crushing lump waste on a cone-inertia crusher, subsequent fine grinding, pressing of the blanks, drying and sintering at 1390-1420 ° С , according to the invention, lumpy waste containing 4, 6, 8 or 10 wt.% cobalt is used, after crushing, the waste is screened, isolating a fraction with a particle diameter of 60-120 μm, and electromagnetic enrichment, then wasp The enriched powder is finely milled in a vibratory mill to an average particle size of 3-4 microns, after having previously introduced 20-30 wt.% of the alloy mixture with the same cobalt content as in the waste, or 20-30 wt.% of the alloy mixture with a cobalt content of 2 or 4 wt.% higher than its content in the waste, while the same amount of cobalt is added to the enriched powder, and sintering is carried out in vacuum.

The inventive method allows to obtain carbide products of low cost with high hardness and strength in bending from waste solid alloys, without the use of acids and other chemical compounds, which increases the environmental friendliness of the technology.

In the study of the prior art, no similar technical solutions were identified that would have been characterized by an identical set of essential features with the achievement of the same technical result as obtained in the proposed technical solution, which allows us to conclude that it meets the criteria of "novelty" and "inventive step". The inventive method can be implemented in industry with the aim of manufacturing carbide products from spent hard alloys using known materials and technical means, which indicates the compliance of the proposed technical solution with the criterion of "industrial applicability".

Examples of the proposed method

Example 1

Lumpy wastes of VK4 grade hard alloy (96% WC + 4% Co) are crushed using an inertial cone crusher, followed by sieving and separation of a fraction with a particle diameter of 60-120 microns. The selected fraction is subjected to electromagnetic enrichment in order to remove iron impurities. The enriched powder is subjected to fine grinding in a vibratory mill to an average particle size of 3-4 microns, while 20 wt.% Of the VK4 solid alloy charge and 4 wt.% Cobalt are introduced into the charge (GOST 9721-79). From the dried and plasticized mixture, blanks of articles are pressed that are sintered in vacuum at 1420 ° C. The obtained carbide material has a bending strength of 1600 MPa and a Vickers hardness of 16 GPa.

The remaining examples were carried out analogously to example 1 and are shown in the table.

As a result of the method, a carbide material with high hardness (up to 17 GPa) and a flexural strength of 1600-1900 MPa was obtained.

The inventive method allows to obtain a hard alloy recovered from waste, comparable in strength and hardness to a standard hard alloy VK8, intended for the manufacture of dies (die-cutting and bending), dies and dies, anti-skid studs for winter tires. It should be considered promising to manufacture, according to this technology, inserts of high-pressure chambers for the synthesis of diamonds and cubic boron nitride.

Example No. Waste mark The addition of cobalt, wt.% Carbide charge additive Hard alloy sintering temperature, ° С Bending Strength, MPa Vickers hardness, GPa mark amount, wt.% one VK4 four VK4 twenty 1420 1600 16 2 - VK8 twenty 1420 1650 17 3 - 25 1420 1650 17 four - thirty 1420 1650 17 5 four twenty 1420 1650 17 6 four 25 1420 1650 17 7 four thirty 1420 1700 16 8 VK6 2 VK6 twenty 1420 1650 17 9 - VK8 twenty 1420 1700 17 10 - 25 1420 1700 17 eleven - thirty 1420 1700 17 12 2 twenty 1410 1700 17 13 2 25 1410 1750 17 fourteen 2 thirty 1410 1750 17 fifteen VK8 2 VK8 twenty 1410 1750 16 16 - VK10 twenty 1410 1800 16 17 - 25 1410 1800 16 eighteen - thirty 1410 1800 16 19 2 twenty 1400 1800 fifteen twenty 2 25 1400 1850 16 21 2 thirty 1400 1850 16 22 VK10 2 VK10 twenty 1400 1800 16 23 - VK12 twenty 1400 1850 fifteen 24 - 25 1400 1850 fifteen 25 - thirty 1400 1850 fifteen 26 2 twenty 1390 1850 fifteen 27 2 25 1390 1900 fifteen 28 2 thirty 1390 1900 fifteen Prototype VK8 - - - 1400 1800 16

Claims (1)

A method of manufacturing carbide products from lumpy wastes of hard alloys containing cobalt, including preparing the mixture by crushing lumpy wastes on a cone-inertia crusher, subsequent fine grinding, pressing the blanks, drying and sintering at 1390-1420 ° C, characterized in that they use lumpy wastes containing 4, 6, 8 or 10 wt.% cobalt, after crushing, the waste is screened, isolating a fraction with a particle diameter of 60-120 microns, and electromagnetic enrichment, then a fine grinding of the enriched powder into vibromel is carried out down to an average particle size of 3-4 microns, having previously introduced into it 20-30 wt.% the charge of the hard alloy with the same cobalt content as in the waste, or 20-30 wt.% the charge of the hard alloy with the cobalt content, by 2 or 4 wt.% exceeding its content in the waste, while the same amount of cobalt is added to the enriched powder, and sintering is carried out in vacuum.