KR20120106882A - A process for recycling of tungsten carbide alloy - Google Patents

Abstract

The present disclosure is a process for recycling tungsten carbide alloys. The method is cost effective and environmentally friendly.

Description

Process for recycling tungsten carbide alloys {A PROCESS FOR RECYCLING OF TUNGSTEN CARBIDE ALLOY}

The present disclosure relates to the recycling of metal alloys. In particular, the present disclosure relates to a method for recycling tungsten carbide alloys. The method is actually cost effective and environmentally friendly.

Huge amounts of tungsten carbide scraps are old inserts and rejections, manufacturers of machine shops, oil exploration companies and machine tools. Generated by them.

Recently scraps have been recycled by following methods-by regrinding of inserts. This method limits the application beyond a certain point, and it is not possible to regrind them. Chemical methods are also available for recycling of the scraps. This includes the oxidation of the scrap followed by alkaline leaching to convert the scrap from the recovered raw tungsten to sodium tungstate. Another method involves fusion using sodium nitrite or sodium nitrate as oxidant and sodium carbonate as diluent to recover tungsten compounds. This method requires high temperatures in the process of extraction. The scrapes are also recycled by a zinc process to directly obtain the tungsten carbide powder. But this is an expensive process and requires huge investment. Other processes prefer leach milling, acid leaching and electrolysis. Various methods Despite the availability, about 35% of the scraps are not recycled because of a lack of capacity.

There is therefore a need for a cost effective process for the extraction of tungsten carbide.

The present disclosure thus discloses oxidizing a tungsten carbide alloy to obtain tungsten oxide and other metallic oxides, grinding the tungsten oxide and other metallic oxides to obtain a powder and purified tungsten carbide alloy. Providing a process for recycling of a tungsten carbide alloy comprising treating the powder with a carburizing gaseous mixture for reducing and carburizing tungsten oxides and other metallic oxides to obtain a powder. .

The present disclosure is directed to oxidizing a tungsten carbide alloy to obtain tungsten oxide and other metallic oxides, to grinding the tungsten oxide and other metallic oxides to obtain a powder, purified tungsten carbide alloy powder A process for recycling of tungsten carbide alloys comprising treating the powder with a carburizing mixture for reducing and carburizing the tungsten oxide and other metallic oxide powders to obtain.

The method is cost effective and environmentally friendly.

The features of the present disclosure will become more fully apparent from the following description with reference to the accompanying drawings. The drawings are to be regarded as only illustrative of various embodiments in accordance with the disclosure, and therefore should not be considered as limiting its scope, and the present disclosure will be described in further specificity and detail through the use of the accompanying drawings. .
1 shows a recycling process of a tungsten carbide alloy in a flowchart.
2 is a microstructure of the powder recycled from Example 1 analyzed by the EDS method.
FIG. 3 is a graph showing the quantity of electrons diffracted diffracted by a particular element during an EDS study from the recycled powder from Example 1. FIG.
4 is a microstructure of the powder recycled from Example 2 analyzed by the EDS method.
5 is a graph showing the amount of electrons diffracted by a particular component during the EDS study from the recycled powder from Example 2. FIG.
6 is a microstructure of the powder recycled from Example 3 analyzed by the EDS method.
FIG. 7 is a graph showing the amount of electrons diffracted by a particular component during the EDS study from the recycled powder from Example 3. FIG.

The present disclosure is directed to oxidizing a tungsten carbide alloy to obtain tungsten oxide and other metallic oxides, to grinding the tungsten oxide and other metallic oxides to obtain a powder, purified tungsten carbide alloy powder A process for recycling of tungsten carbide alloys comprising treating the powder with a carburizing mixture for reducing and carburizing the tungsten oxide and other metallic oxide powders to obtain.

In one embodiment of the present disclosure, the oxidation is carried out in an oxidation furnace in a temperature range of about 400 ° C. to about 1000 ° C., preferably at about 950 ° C.

In another embodiment of the present disclosure, the oxidation is carried out using an oxidizing agent selected from the group comprising air and oxygen, preferably air.

In another embodiment of the present disclosure, the milling step, ball mill, Attritor Mill, High Speed Intensive mill (High Speed Intensive mill); Preferably by a method selected from the group comprising a ball mill.

In another embodiment of the present disclosure, the milling step is performed for period ranging from about 0.5 hours to about 10 hours, preferably for about 2 hours.

In another embodiment of the present disclosure, the carburizing mixture comprises hydrogen, nitrogen, carbon monoxide, methane, carbon dioxide, compressed natural gas (CNG), liquefied petroleum gas (LPG) and mixtures thereof. It is selected from the group containing.

In still another embodiment of the present disclosure, the carburizing mixture is a combination of about 10% liquefied petroleum gas and 90% nitrogen.

In another embodiment of the present disclosure, the treating with the carburized mixture is performed for a period ranging from about 1 hour to about 15 hours, preferably for 3 hours.

In another embodiment of the present disclosure, the treating with the carburized mixture to obtain the purified tungsten carbide alloy powder is carried out at a temperature in a range from about 800 ° C to about 1400 ° C, preferably at about 1050 ° C. It is carried out in a reduction furnace.

In another embodiment of the present disclosure, the purified tungsten carbide alloy powder has a temperature range of about 300 ° C. to about 200 ° C. in nitrogen, preferably up to about 200 ° C., and then about 35 ° C. to about 25 in air. C, preferably to about 25 ° C.

In one embodiment of the present disclosure, the tungsten carbide alloy includes tungsten carbide alloy scraps, residual and off-quality wires, turnings, grindings, worn inserts Any forms of worry out machine tools that process drill outs, drill bits, cutters, die blocks and tungsten carbide alloys Physically varying items such as Thus, for purposes of this disclosure, the term "tungsten carbide alloy" is used to include some and all of the various forms mentioned above, but is not limited thereto.

In one embodiment of the present disclosure, recycling of the tungsten carbide alloy includes recycling of the tungsten carbide alloy to obtain a pure form of tungsten carbide alloy powder from tungsten carbide alloy scraps. Thus, for the purposes of this disclosure, the term "recycling tungsten carbide alloy" is used to include some and all of the various forms mentioned above, but is not limited thereto.

In one embodiment of the present disclosure, the present disclosure provides an initial powder as compared to other processes for recycling the tungsten carbide alloy from worn out inserts and rejected products. It is a very cost effective solution to obtain quality at par.

One embodiment of the present disclosure is directed to converting the tungsten carbide into a mixed powder having exactly the same chemical composition as the mixture produced from the initial powders and having other qualitative parameters pressurized back into inserts ( convert back Use thermo mechanical treatment. The proposed process is a thermomechanical process and therefore produces no effluent.

In one embodiment of the present disclosure, the proposed process uses simpler and less expensive machines and operations, thus greatly reducing the cost of recycling.

In another embodiment, the present disclosure includes the oxidation of the tungsten carbide scraps at a suitable temperature for converting the alloy elements into their oxides. The oxides are milled to convert them into powders. The oxidized powders are mixed with reducing agents such as carburized gas and reduced at appropriate temperatures and environments to convert back to the original alloy powder mixture.

In another embodiment of the present disclosure, the principle behind the present disclosure is to convert the components into their oxides which are very light and easily crushable. The oxide powders are then reduced to convert back to the original components. Carbon present in the tungsten carbide alloy as carbides escapes as carbon-di-oxide during oxidation. This problem is addressed using carbothermic reduction. This process can produce a high quality powder mixture at a very low cost, due to the rare requirement that more expensive initial powders can be replaced since the process does not require any more expensive equipment or consumables. can produce a high quality powder mix at a very cheaper rate by which the requirement for scarce, costlier virgin powders can be substituted, since the process is not calling for any costlier equipments or consumables).

In one embodiment of the present disclosure, during oxidation, tungsten oxide, cobalt oxide and other metallic oxides are formed. In the reduction process, which is a carbon heat process, the carburizing atmosphere can be maintained with the help of hydrogen, nitrogen, carbon monoxide, methane, carbon dioxide, compressed natural gas (CNG), liquefied petroleum gas (LPG) and mixtures thereof. will be.

The wide range of percentages of carburized gas of the hydrogen mixture is from 0.7% to 30%.

In another embodiment of the present disclosure, the oxidant present in the furnace chamber is air.

In one embodiment of the present disclosure, the final properties of the tungsten carbide powder include the following:

1. Chemical analysis for finding percentages of tungsten, carbon, cobalt & oxygen using Electron Diffraction Studies;

2. Microstructural analysis (in mass production, this may not be required)

3. Particle size analysis.

One embodiment of the present disclosure is further described by the following examples, which should not be construed to limit the scope of the present disclosure.

10 kgs of tungsten carbide alloy scraps were oxidized in 950 ° C., atmospheric pressure, air for 10 hours. The oxidized powder was then ground in a ball mill for about 2 hours. This oxide powder was simultaneously reduced and carburized by a carburizing mixture consisting of 10% LPG and 90% nitrogen at 1050 ° C. for 6 hours and then cooled to 200 ° C. in nitrogen and then to room temperature in air.

Comparative Analysis of Initial Powder and Recycled Powder of Tungsten Carbide Alloy Powder

2 is a microstructure of the powder recycled from Example 1 analyzed by EDS method. 3 is a graph showing the amount of electrons diffracted by a specific component from the recycled powder extracted from Example 1. FIG.

Table 2, shown below, shows the results of the quantitative analysis of the recycled powder from Experiment 1.

ZAF Method Standardless Quantitative Analysis

10 Kgs of tungsten carbide alloy scraps were oxidized in air at 950 ° C., atmospheric pressure for 10 hours. The oxidized powder was then ground in a ball mill for about 2 hours. This oxide powder was simultaneously reduced and carburized with a carburizing mixture consisting of 10% LPG and 90% nitrogen at 1050 ° C. for 2 hours and cooled to 200 ° C. in nitrogen and then to room temperature in air.

Comparative Analysis of Initial Powder and Recycled Powder of Tungsten Carbide Alloy Powder

4 is the microstructure of the powder recycled from Example 2 analyzed by the EDS method. FIG. 5 is a graph showing the amount of electrons diffracted by a specific component from recycled powder extracted from Example 2. FIG.

Table 4, shown below, shows the results of the quantitative analysis of the recycled powder from Experiment 2.

ZAF Method Nonstandard Quantitative Analysis

10 Kgs of tungsten carbide alloy scraps were oxidized in air at 950 ° C., atmospheric pressure, for 10 hours. The oxidized powder was then ground in a ball mill for about 2 hours. This oxide powder was simultaneously reduced and carburized with a carburizing mixture consisting of 10% LPG and 90% nitrogen at 1050 ° C. for 3 hours and then cooled to 200 ° C. in nitrogen and then to room temperature in air.

Analysis of the leached and reduced powder revealed that the reduction was complete and the carbon content was found at 6.3%, the exact stochiometric composition. Furthermore, Cobalt found at around 9%, titanium found at 1.3% which confirms to the requirements of a ready to press Tungsten to confirm the need to pressurize tungsten carbide powder. Carbide powder).

Comparative Analysis of Initial Powder and Recycled Powder of Tungsten Carbide Alloy Powder

6 is the microstructure of the powder recycled from Example 3 analyzed by the EDS method. FIG. 7 is a graph showing the amount of electrons diffracted by a specific component from the powder extracted from Example 3. FIG.

Table 6, shown below, shows the results of the quantitative analysis of the recycled powder from Experiment 3.

ZAF Method Nonstandard Quantitative Analysis

Claims (10)

a) oxidizing a tungsten carbide alloy to obtain tungsten oxides and other metallic oxides;
b) grinding the tungsten oxides and other metallic oxides to obtain a powder; And
c) treating the powder with a carburizing mixture for reducing and carburizing the tungsten oxides and other metallic oxides of the powder to obtain a purified tungsten carbide alloy powder
Process for recycling of tungsten carbide alloy, comprising.
The method of claim 1,
Wherein said oxidation is carried out in an oxidation furnace in a temperature range of about 400 ° C. to about 1000 ° C., preferably at about 950 ° C. 18.
The method of claim 1,
Wherein said oxidation is carried out with an oxidizing agent selected from the group comprising air and oxygen, preferably air.
The method of claim 1,
The milling step, ball mill, attrition mill, high speed intensive mill; Process for recycling of tungsten carbide alloys, preferably carried out by a method selected from the group comprising a ball mill.
The method of claim 1,
Wherein said grinding is carried out for a period ranging from about 0.5 hours to about 10 hours, preferably for about 2 hours.
The method of claim 1,
The carburizing mixture is selected from the group consisting of air, hydrogen, nitrogen, carbon monoxide, methane, carbon dioxide, compressed natural gas (CNG), liquefied petroleum gas (LPG) and mixtures thereof for recycling of tungsten carbide alloys. process.
The method according to claim 6,
And wherein the carburized mixture is a combination of about 10% liquefied petroleum gas and about 90% nitrogen.
The method of claim 1,
Wherein said treating with said carburized mixture is carried out for a period ranging from about 1 hour to about 15 hours, preferably for 3 hours.
9. The method of claim 8,
The step of treating with the carburizing mixture to obtain the purified tungsten carbide alloy powder is carried out in a reduction furnace at a temperature range of about 800 ° C. to about 1400 ° C., preferably at about 1050 ° C. Process for recycling of carbide alloys.
10. The method of claim 9,
The purified tungsten carbide alloy powder is cooled to about 300 ° C. to about 200 ° C. in nitrogen, preferably to about 200 ° C., and then to about 40 ° C. to about 20 ° C., preferably about 25 ° C. in air. Process for recycling the tungsten carbide alloy.

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