1. A method for recycling hard alloy scrap, wherein the hard alloy scrap contains elemental tungsten and/or tungsten carbide, and is characterized in that: the method comprises the following steps:

step 1: mixing the hard alloy waste with sodium silicate and an additive to obtain a mixture, wherein the additive contains at least one of calcium element or magnesium element;

step 2: roasting the mixture at 400-1000 ℃ for 1-24 h in an oxygen-containing atmosphere to obtain a roasted material, wherein during roasting, elemental tungsten and/or tungsten carbide in the hard alloy waste, sodium silicate and an additive react at a high temperature to generate sodium tungstate, calcium silicate and/or magnesium silicate;

and step 3: and (3) soaking the roasted material in water to obtain a solid-liquid mixture, and removing filter residues after solid-liquid separation to obtain a sodium tungstate solution.

2. The method for recycling cemented carbide scrap according to claim 1, characterized in that: the hard alloy waste is at least one of a floor material, a dust collecting material, a grinding material, a waste material, a soft waste material or hard alloy generated in the production process of hard alloy, a high-specific gravity alloy hard waste material or tungsten powder, and a floor material, a dust collecting material, a grinding material and a waste material generated in the production process of tungsten carbide powder.

3. The method for recycling cemented carbide scrap according to claim 1, characterized in that: the mass content of tungsten in the hard alloy waste is 5-120% calculated by tungsten oxide, and the tungsten exists in the form of tungsten carbide and/or tungsten simple substance.

4. The method for recycling cemented carbide scrap according to claim 1, characterized in that: in the step 1, the additive is at least one of calcium carbonate, calcium oxide, calcium hydroxide and calcium hypochlorite;

optionally, the additive is added in a ratio of the amount of Ca in the additive to the amount of Si in the sodium silicate of 1.1 to 3, preferably 1.5 to 2.

5. The method for recycling cemented carbide scrap according to claim 1, characterized in that: in the step 1, the additive is at least one of basic magnesium carbonate, magnesium oxide, magnesium hydroxide, magnesium chloride and magnesium sulfate;

optionally, the additive is added in an amount such that the ratio of the amount of Mg in the additive to the amount of Si in the sodium silicate is 1.1 to 3, preferably 1.5 to 2.

6. The method for recycling cemented carbide scrap according to any one of claims 1-5, characterized by: in the step 1, the addition amount of sodium silicate is 2.1-6, preferably 3-4.5, based on the amount of Na in sodium silicate to W in the cemented carbide scrap.

7. The method for recycling cemented carbide scrap according to claim 1, characterized in that: in the roasting process in the step 2, the calcium element or the magnesium element in the additive is utilized to drive silicon in the sodium silicate to a slag phase, and formed calcium silicate and/or magnesium silicate is used as a wrapping agent to be combined with viscous substances in the hard alloy waste material for slagging, so that the inner wall of the roasting furnace is prevented from being caked.

8. The method for recycling cemented carbide scrap according to claim 1 or 7, characterized in that: in the step 2, the oxygen-containing atmosphere is air or oxygen-enriched air or oxygen.

9. The method for recycling cemented carbide scrap according to claim 1 or 7, characterized in that: in the step 2, the temperature is 600-800 ℃, and the time is 8-12 h.

10. The method for recycling cemented carbide scrap according to claim 1, characterized in that: and in the step 3, the water leaching is to mix the roasted material with water, and an acidic or alkaline reagent is not required to be added for assisting leaching.

Background

Cemented carbide is an alloy material made from a hard compound of refractory metals and a binder metal by a powder metallurgy process. The production process of the hard alloy comprises the steps of producing a floor material, a dust collecting material, a grinding material and a waste material in the production process of the hard alloy or producing the floor material, the dust collecting material, the grinding material and the waste material in the production process of tungsten powder and tungsten carbide powder, and is called hard alloy waste for short. Tungsten carbide and simple substance tungsten are widely applied in the preparation of hard alloy, and the generated hard alloy waste mainly contains the tungsten carbide and the simple substance tungsten, and the hard alloy waste is recycled, thereby being beneficial to the full utilization of resources and solving the problems of waste accumulation and pollution.

The existing hard alloy waste recovery technology has various defects, for example, the zinc melting method is based on that zinc and binding phase metals (cobalt and nickel) in hard alloy can form low-melting-point alloy, so that the binding metals are separated from the hard alloy and form zinc-cobalt solid solution alloy liquid with the zinc, thereby destroying the structure of the hard alloy, compact alloy becomes a loose hard phase framework, and the zinc cannot react with various refractory metal carbides, thereby achieving the purpose of recovering tungsten. However, the method is only suitable for processing hard alloy with cobalt content lower than 10%, and has high power consumption, high requirement on zinc steam recovery equipment and large zinc volatilization pollution.

The method for smelting the saltpeter is to convert tungsten carbide in the hard alloy into sodium tungstate at high temperature by using the saltpeter as an oxidant, and oxidize other impurity elements into metal oxides which are insoluble in water, thereby achieving the purpose of recovering tungsten. However, the method has long industrial process, the used raw and auxiliary materials are expensive, the production cost is high, and the discharged tail gas causes pollution to the environment; and the waste water produced in the subsequent APT production process is more, and the loss of raw and auxiliary materials is large.

The roasting alkali leaching method is to convert hard alloy into tungsten oxide through oxidation roasting, and the tungsten oxide is subjected to alkali leaching reaction to generate sodium tungstate, so that the aim of tungsten recovery is fulfilled. However, in the treatment process of the method, the roasting equipment is seriously caked, the tungsten content in the slag is high, the recovery rate is low, and the treatment cost of the secondary slag is high; and APT is produced by the traditional metallurgical process subsequently, so that more waste water is produced in the production process, and the loss of raw and auxiliary materials is large.

Disclosure of Invention

The invention aims to overcome the problems in the existing hard alloy waste recovery, and provides a hard alloy waste recovery method, wherein tungsten in the hard alloy waste is recovered, the hard alloy waste is mainly tungsten carbide or simple substance tungsten, other elements are mainly cobalt, nickel, iron, copper, chromium and the like, the waste is conventional commercial hard alloy waste, and the hard alloy waste is mainly soft waste such as a floor slab, a dust collecting material, a grinding material and a waste material generated in the production process of hard alloy, high-specific gravity alloy or tungsten powder and hard waste such as a floor slab, a dust collecting material, a grinding material and a waste material generated in the production process of hard alloy, high-specific gravity alloy or tungsten powder and tungsten carbide powder.

In order to recover tungsten element in the hard alloy waste material, the existing zinc melting method, saltpeter melting method and roasting alkaline leaching method all have problems of different degrees. The inventors have tried, based on practical experience, to accomplish the main extraction operation in one step by the pyrometallurgical method, introducing sodium silicate and additives, wherein sodium silicate is not generally used in pyrometallurgical methods because it is prone to furnace accretion problems, and sodium carbonate is generally used when sodium salt addition is required.

In the invention, the inventor utilizes the additive containing calcium and/or magnesium elements, tungsten or tungsten carbide in the waste material reacts with sodium silicate and calcium and/or magnesium containing substances to generate sodium tungstate and calcium silicate and/or magnesium silicate under the high temperature condition, and silicon is forced to enter slag phase, namely forms calcium silicate and/or magnesium silicate with calcium or magnesium, so that other adhesive raw materials of the hard alloy such as oxides or salt forms of cobalt nickel iron copper chromium and the like can be wrapped, the effect of avoiding sintering and sintering is achieved, and meanwhile, the one-step pyrogenic process is realized to generate sodium tungstate, and the tungsten loss caused by the formation of calcium tungstate and magnesium tungstate is avoided. Finally, the sodium tungstate solution can be obtained by water leaching without alkaline or acidic condition leaching.

Through a great deal of research, the inventor develops a method for recycling hard alloy waste, which can recycle valuable metal tungsten element in the hard alloy waste by using sodium silicate. In the development process, it is generally considered that sodium silicate has weak alkalinity and activity, and the viscosity of sodium silicate in a high-temperature environment is high, so that sodium silicate cannot be used for pyrogenically recovering valuable metal tungsten in hard alloy scrap, and the inventors have tried to recover valuable metal tungsten in hard alloy scrap by using sodium silicate in a pyrometallurgical process. In the course of the inventors 'continuous trial, it was surprisingly found that the addition of calcium-and/or magnesium-containing substances in the pyrometallurgical process with the addition of sodium silicate can promote the reaction, and valuable metal tungsten in the cemented carbide scrap can be effectively recovered without causing a sticking phenomenon, so that the applicant's research is a significant progress in the recovery of cemented carbide scrap.

The specific scheme is as follows:

a method for recycling cemented carbide scrap containing elemental tungsten and/or tungsten carbide, comprising the steps of:

step 1: mixing the hard alloy waste with sodium silicate and an additive to obtain a mixture, wherein the additive contains at least one of calcium element or magnesium element;

step 2: roasting the mixture at 400-1000 ℃ for 1-24 h in an oxygen-containing atmosphere to obtain a roasted material, wherein during roasting, elemental tungsten and/or tungsten carbide in the hard alloy waste, sodium silicate and an additive react at a high temperature to generate sodium tungstate, calcium silicate and/or magnesium silicate;

and step 3: and (3) soaking the roasted material in water to obtain a solid-liquid mixture, and removing filter residues after solid-liquid separation to obtain a sodium tungstate solution.

Further, the hard alloy waste is at least one of a floor material, a dust collecting material, a grinding material, a waste material, a soft waste or hard alloy, a high specific gravity alloy hard waste or tungsten powder, and a floor material, a dust collecting material, a grinding material and a waste material produced in a tungsten carbide powder production process.

Further, the mass content of tungsten in the hard alloy waste is 5-120% in terms of tungsten oxide, and the tungsten exists in the form of tungsten carbide and/or tungsten simple substance.

Further, in the step 1, the additive is at least one of calcium carbonate, calcium oxide, calcium hydroxide and calcium hypochlorite;

optionally, the additive is added in a ratio of the amount of Ca in the additive to the amount of Si in the sodium silicate of 1.1 to 3, preferably 1.5 to 2.

Further, in the step 1, the additive is at least one of basic magnesium carbonate, magnesium oxide, magnesium hydroxide, magnesium chloride and magnesium sulfate;

optionally, the additive is added in an amount such that the ratio of the amount of Mg in the additive to the amount of Si in the sodium silicate is 1.1 to 3, preferably 1.5 to 2.

Further, in step 1, the amount of sodium silicate added is 2.1 to 6, preferably 3 to 4.5, in terms of the ratio of Na in sodium silicate to the amount of W in the cemented carbide scrap.

Further, in the roasting process in the step 2, calcium element or magnesium element in the additive is utilized to drive silicon in the sodium silicate to a slag phase, and formed calcium silicate and/or magnesium silicate is used as a wrapping agent to be combined with viscous substances in the hard alloy waste material for slagging, so that the inner wall of the roasting furnace is prevented from being sintered.

Further, in the step 2, the oxygen-containing atmosphere is air or oxygen-enriched air or oxygen. Under the oxygen-containing atmosphere, tungsten in the tungsten simple substance and/or tungsten carbide is oxidized, thereby promoting the generation of sodium tungstate.

Furthermore, the temperature in the step 2 is 600-800 ℃, and the time is 8-12 h.

Further, the water leaching in step 3 is to mix the roasted material with water, and no acidic or alkaline reagent is added for assisting leaching.

Has the advantages that: the method provided by the invention can recover tungsten in the hard alloy waste material, and the recovery rate can reach more than 98%. In addition, the method provided by the invention is simple to operate, low in investment cost, low in medicament consumption, low in decomposition cost, free of the problem of roasting and furnace forming, suitable for industrial production and has great popularization significance.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available. In the following examples, "%" means weight percent, unless otherwise specified.

The hard alloy waste materials adopted in the embodiment are waste materials generated in the production process of tungsten carbide, and comprise floor plates, dust collecting materials, grinding materials, waste materials and the like generated in the production process. The main element contents of the cemented carbide scrap are shown in table 1:

table 1 hard alloy scrap composition table

Note: due to the composition difference of the hard alloy scraps of different batches, the content of each element is changed, wherein the content of tungsten is related to the addition amount of the additive and the decomposition rate, only the content of tungsten is marked in the following examples, and according to the convention in the field, the tungsten oxide content is measured by tungsten oxide, and it is noted that the tungsten oxide content is a representation method of the tungsten content in the scraps, and the tungsten element exists in the form of tungsten simple substance and/or tungsten carbide substantially regardless of the existence form of tungsten.

Example 1

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2Kg of hard alloy waste (the mass content of tungsten oxide is 5 percent), and uniformly mixing the hard alloy waste with 0.36Kg of calcium carbonate and 0.15Kg of sodium silicate to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 900 ℃, and the roasting time is 1 h;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.18%.

Example 2

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2.5Kg of hard alloy waste (the mass content of tungsten oxide is 30 percent), and uniformly mixing the hard alloy waste with 1.12Kg of calcium oxide and 0.98Kg of sodium silicate glass to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting at 800 ℃ for 16 h;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.32%.

Example 3

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2Kg of hard alloy waste (the mass content of tungsten oxide is 50 percent), and uniformly mixing the hard alloy waste with 0.95Kg of calcium hydroxide and 1.05Kg of sodium silicate to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 1000 ℃, and the roasting time is 8 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.63%.

Example 4

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: 1.50Kg of hard alloy waste (the mass content of tungsten oxide is 80%) is uniformly mixed with 1.22Kg of calcium hypochlorite and 0.94Kg of sodium silicate glass to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 600 ℃, and the roasting time is 4 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.35%.

Example 5

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: 1.80Kg of hard alloy waste (the mass content of tungsten oxide is 100%) is uniformly mixed with 0.55Kg of calcium carbonate, 0.31Kg of calcium oxide and 1.00Kg of sodium silicate glass to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 500 ℃, and the roasting time is 12 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.78%.

Example 6

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2.20Kg of hard alloy waste (the mass content of tungsten oxide is 120 percent), and uniformly mixing the hard alloy waste with 1.50Kg of calcium carbonate and 1.66Kg of sodium silicate to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 400 ℃, and the roasting time is 24 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching out to remove residue by using solid-liquid separation equipment to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.85%.

Example 7

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2.10Kg of hard alloy waste (the mass content of tungsten oxide is 5 percent), and uniformly mixing the hard alloy waste with 0.35Kg of basic magnesium carbonate and 0.16Kg of sodium silicate to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 1000 ℃, and the roasting time is 2 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.07%.

Example 8

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2.70Kg of hard alloy waste (the mass content of tungsten oxide is 32 percent), and uniformly mixing the hard alloy waste with 0.80Kg of magnesium oxide and 1.00Kg of sodium silicate glass to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 900 ℃, and the roasting time is 12 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.25%.

Example 9

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2.00Kg of hard alloy waste (the mass content of tungsten oxide is 48 percent), and uniformly mixing the hard alloy waste with 0.75Kg of magnesium hydroxide and 1.00Kg of sodium silicate to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 800 ℃, and the roasting time is 8 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.55%.

Example 10

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: 1.50Kg of hard alloy waste (the mass content of tungsten oxide is 80%) is taken and evenly mixed with 0.81Kg of magnesium chloride and 0.95Kg of sodium silicate glass to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 600 ℃, and the roasting time is 4 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.33%.

Example 11

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: 1.80Kg of hard alloy waste (the mass content of tungsten oxide is 100%) is uniformly mixed with 1.26Kg of magnesium sulfate and 1.00Kg of sodium silicate glass to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 400 ℃, and the roasting time is 16 h;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.28%.

Example 12

A method of recycling cemented carbide scrap comprising:

the method comprises the following steps: taking 2.00Kg of hard alloy waste (the mass content of tungsten oxide is 120 percent), and uniformly mixing the hard alloy waste with 0.60Kg of magnesium oxide and 1.65Kg of sodium silicate to obtain a mixture;

step two: placing the mixture obtained in the step one in a roasting furnace for roasting, wherein the roasting temperature is 500 ℃, and the roasting time is 24 hours;

step three: and (5) soaking the roasted material obtained in the step two in water. And filtering the feed liquid after water leaching by using solid-liquid separation equipment to remove material residues to obtain a sodium tungstate solution, wherein the tungsten recovery rate is 98.55%.

Comparative example 1

Referring to example 6, the other conditions were not changed, and the final recovery rate of tungsten was only 58.75% by changing the addition amount of calcium carbonate to 0.50Kg in example 6.

Comparative example 2

Referring to example 1, the calcination temperature in example 1 was changed to 200 ℃ alone without changing other conditions, and the final recovery rate of tungsten was only 63.17%.

Comparative example 3

Referring to example 1, except for the change of the other conditions, only sodium silicate in example 1 was replaced with sodium carbonate, and as a result, it was found that the sintering was severe and the loss of the fired material was large during firing.

Comparative example 4

Referring to example 1, the calcium carbonate in example 1 was removed to find that the material was strongly bonded and the decomposition rate was low, and the final recovery rate of tungsten was only 75.83%

Comparative example 5

Referring to example 12, the magnesium oxide addition amount in example 12 was changed to 0.20Kg, and the final tungsten recovery rate was only 63.48% without changing other conditions.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.