Treatment method of hard alloy waste tungsten powder

Abstract

The invention relates to the technical field of solid waste recovery treatment, in particular to a treatment method of hard alloy waste tungsten powder. The invention provides a treatment method of hard alloy waste tungsten powder, which comprises the following steps: mixing the hard alloy waste tungsten powder and an acidic oxidant into slurry, and roasting at the temperature of more than 180 DEG C and less than 300 DEG C to obtain an oxidized roasted material; and immersing the oxidizing roasting material into water, stirring, and separating to obtain a tungstic acid solid. According to the method, the waste is roasted in concentrated sulfuric acid at low temperature, so that the oxidation reaction can be enhanced, the defects of high energy consumption and low recovery rate in the traditional high-temperature air roasting process are avoided, and the method has the advantages of short flow, low energy consumption and high recovery rate.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste recycling and treatment, and particularly to a method for treating waste tungsten powder of cemented carbide. Background Art

[0003] Since cemented carbide has high hardness, high density and is difficult to be dissolved by common inorganic acids and alkalis. At present, the main methods for recycling cemented carbide are: zinc melting method, high-temperature treatment method, cracking sintering method, mechanical crushing method, chemical treatment method, electrolysis method, as well as methods such as passing high-pressure oxygen, leaching with ammonia water or ammonium solution, and carbonyl compound method and sublimation of tungsten trioxide with water vapor. The zinc melting method has a simple process, but it is easy to introduce impurities, has a low recovery rate and high energy consumption. Moreover, the ratio control of zinc and cemented carbide is crucial. If there is insufficient zinc, the cemented carbide cannot be completely melted and dispersed, and too much zinc is likely to remain in the recycled product and affect its performance. This method is applicable to cemented carbide with a cobalt content of less than 12%. The electrochemical method is applicable to cemented carbide with a cobalt content greater than 10%. The recycling process requires corrosive chemical agents, and the surface passivation effect is likely to cause the reaction rate to decrease. The mechanical crushing method has a simple process, but due to the high hardness and high density of cemented carbide, the crushing is difficult. In the crushing process, some metal devices are inevitably used, which is easy to introduce impurities. The acid leaching method has a long subsequent regeneration process, high cost and produces harmful gases.

[0004] At present, the mainstream method is the redox method, mainly using a rotary kiln to calcine in the air to oxidize tungsten carbide powder or tungsten powder and then leach with alkali for recovery. However, in the production process of cemented carbide, in order to improve the hardness and other properties of the alloy material, a coating is added or other antioxidant substances are incorporated, resulting in incomplete oxidation. Moreover, high-temperature oxidation roasting will cause the silicon-containing phase to melt, resulting in furnace caking, affecting the roasting operation, restricting the effective recycling of waste materials, and the tungsten recovery is incomplete, with high energy consumption and problems such as waste gas pollution. In this regard, the current research direction mainly focuses on treating the products after roasting, such as acid leaching treatment of the roasted materials, etc., and often ignores the improvement before and during roasting;

[0005] Therefore, it is particularly important to develop an innovative method for treating waste tungsten powder of cemented carbide with a short process, low energy consumption and high recovery rate. Summary of the Invention

[0006] In order to solve the deficiencies in the above-mentioned prior art that the redox method is affected by adding a coating or incorporating other antioxidant substances in the production process of cemented carbide to improve the hardness and other properties of the alloy material, resulting in incomplete oxidation, and high-temperature oxidation roasting will cause the silicon-containing phase to melt, resulting in furnace caking, affecting the roasting operation, and restricting the effective recycling of waste materials, the present invention provides a method for treating waste tungsten powder of cemented carbide.

[0007] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0008] The present invention provides a method for treating hard alloy waste tungsten powder, comprising the following steps:

[0009] Mix the hard alloy waste tungsten powder with an acidic oxidant to form a slurry, and then calcine at a temperature above 180°C and below 300°C to obtain an oxidized calcined material;

[0010] Immerse the oxidized calcined material in water, stir and separate to obtain tungsten acid solid.

[0011] In one embodiment, the proportion of tungsten content in the hard alloy waste tungsten powder is above 70%.

[0012] In one embodiment, the cobalt-nickel content in the hard alloy waste tungsten powder is 1% - 2%, and the silicon content in the hard alloy waste tungsten powder is 5% - 10%.

[0013] In one embodiment, the particle size of the hard alloy waste tungsten powder is between 30 mesh and 50 mesh.

[0014] In one embodiment, the mass ratio of the acidic oxidant to the acid material of the waste tungsten powder is 1.5 - 4.0:1.0.

[0015] In one embodiment, the acidic oxidant is an acidic oxidant with an oxidizing property greater than or equal to concentrated sulfuric acid with a mass fraction of 98% or more.

[0016] In one embodiment, the acidic oxidant is concentrated sulfuric acid with a mass fraction of 98% or more, and the calcination time is 100 - 150 min.

[0017] In one embodiment, the solid-liquid ratio of the water to the oxidized calcined material is 3 - 6.

[0018] In one embodiment, the stirring temperature is 0 - 100°C, and the stirring time is 60 - 120 min.

[0019] In one embodiment, the separation is solid-liquid separation.

[0020] Based on the above, the treatment method provided by the present invention utilizes the superior physical and chemical properties of concentrated sulfuric acid, which can greatly improve the activity of reactants. Based on the fact that sulfuric acid is an asymmetric molecule, its H + has a very small volume and has a strong polarization effect on O -2The electron cloud of [substance] deforms and penetrates into it, neutralizing part of the negative charge of the -2 valence O, weakening the binding force between the -2 valence O and the central atom +6 valence S, thus destroying the stability of the sulfuric acid molecule, making the +6 valence S easily accept external electrons and be reduced. Therefore, concentrated sulfuric acid is a rather strong acidic oxidant. Especially when heated, its oxidizing ability is particularly remarkable and it can react with some non-metals and the vast majority of metals. Therefore, on the one hand, metals such as Zn, Fe, and Al in the waste tungsten powder can form sulfates and enter the solution, while tungsten carbide and tungsten in the waste tungsten powder are oxidized to WO3 and react with the acid to form tungstic acid solids, thereby realizing the separation of tungsten from other impurities and then achieving the efficient recovery of tungsten.

[0021] Other features and beneficial effects of the present invention will be described in the subsequent specification, and partly will become obvious from the specification, or can be understood by implementing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts; in the following description of the positional relationship of the drawings, unless otherwise specified, the directions shown by the components in the drawings are used as the reference.

[0023] Figure 1 It is a flowchart of a method for treating waste tungsten powder of cemented carbide provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention; the technical features designed in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention pertains, and should not be construed as a limitation to the present invention; it should be further understood that the terms used in the present invention should be understood as having meanings consistent with their meanings in the context of this specification and the relevant fields, and should not be understood in an idealized or overly formal sense, unless clearly defined as such in the present invention.

[0026] In the prior art, after most traditional tungsten waste materials are calcined, tungsten or tungsten carbide is oxidized to WO3, and then in subsequent stages, acid leaching is used to make the acid react with WO3 to obtain tungstic acid.

[0027] However, the inventor found through research that by adding concentrated sulfuric acid to make a slurry in advance before calcination, the concentrated sulfuric acid can play the following three roles at the calcination temperature: 1. Oxidize tungsten or tungsten carbide to WO3; 2. React the acid with WO3 to generate solid tungstic acid to separate tungsten from other impurities; 3. Make metals such as zinc (Zn), iron (Fe), and aluminum (Al) in the waste tungsten powder materials form sulfates and enter the solution.

[0028] Please refer to Figure 1 , an embodiment of the present invention provides a method for treating waste tungsten powder materials of cemented carbide, including the following steps:

[0029] Step 1: Mix the waste tungsten powder materials of cemented carbide with an acidic oxidant to make a slurry, and then calcine at a temperature above 180°C and below 300°C to obtain an oxidized calcined material;

[0030] The waste tungsten powder materials refer to powdery tungsten-containing wastes generated during the production, processing, or use of cemented carbide; more specifically, the waste tungsten powder materials of cemented carbide are at least one of floor materials, dust collection materials, grinding materials, waste products, soft wastes generated during the production of cemented carbide, or floor materials, dust collection materials, grinding materials, waste products generated during the production of cemented carbide, high specific gravity alloy hard wastes, or tungsten powder and tungsten carbide powder. The proportion of tungsten content in the waste tungsten powder materials of cemented carbide is above 70%, the cobalt-nickel content is 1% - 2%, and the silicon content is 5% - 10%; in some preferred embodiments, control the particle size of the waste tungsten powder materials of cemented carbide to be between 30 mesh and 50 mesh to increase the contact area between the waste tungsten powder materials of cemented carbide and the acidic oxidant. The particle size of the waste tungsten powder materials of cemented carbide can specifically be 30, 35, 40, 45, 50 mesh, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable; more preferably, control the particle size of the waste tungsten powder materials of cemented carbide to be 40 mesh.

[0031] In specific implementation, control the acid-to-material mass ratio of the acidic oxidant to the waste tungsten powder material to be 1.5 - 4.0:1.0; specifically, this acid-to-material ratio can be 1.5:1.0, 2.0:1.0, 2.5:1.0, 3.0:1.0, 3.5:1.0, 4.0:1.0, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable; controlling this acid-to-material ratio can, on the one hand, ensure that the tungsten in the waste tungsten powder material can be completely oxidized by the acid and react to obtain tungstic acid, and on the other hand, can fully react with impurities such as zinc (Zn), iron (Fe), and aluminum (Al) in the waste material.

[0032] In some preferred embodiments, the acidic oxidant is an acidic oxidant with an oxidizing property greater than or equal to concentrated sulfuric acid with a mass fraction of 98% or more; specifically, the acidic oxidant can be concentrated sulfuric acid with a mass fraction of 98%, etc.

[0033] In some preferred embodiments, the acidic oxidant is concentrated sulfuric acid with a mass fraction of 98% or more, the roasting temperature is above 180°C and below 300°C, and the roasting time is 100 - 150 min. It should be noted that within this temperature range, the tungsten therein can be completely oxidized. However, since the boiling point of concentrated sulfuric acid is 337°C, in order to avoid the boiling of concentrated sulfuric acid, the roasting temperature is controlled at a temperature below the boiling point of concentrated sulfuric acid, such as within 300°C.

[0034] It should also be noted that since the waste tungsten powder material of cemented carbide contains antioxidants such as nickel, the effect of oxidative calcination in air is not very ideal. According to the conventional method, even after roasting and then leaching with ordinary acid, it is impossible to oxidize tungsten or tungsten carbide, and most of the existing roasting is carried out at a temperature of 800°C and above, with extremely high energy consumption. However, the embodiment of the present invention, in cooperation with the strong oxidizing property of concentrated sulfuric acid, can not only achieve roasting at a low temperature, but also because the acid can better react with other metals during this process, eliminating the influence, so the oxidation effect is better, and finally the efficient recovery of tungsten is realized.

[0035] Step 2: Immerse the oxidation roasting material in water, stir, and separate to obtain tungstic acid solid.

[0036] In some preferred embodiments, the solid-to-liquid ratio of the water to the oxidation roasting material is 3 - 6. Specifically, this solid-to-liquid ratio can be 3, 4, 5, 6, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable; the stirring temperature is 0 - 100°C, and the stirring time is 60 - 120 min; further, through solid-liquid separation, tungstic acid solid and waste liquid are obtained.

[0037] Step 3: Dissolve the tungstic acid solid in alkali to obtain a sodium tungstate solution, detect the WO3 concentration in the sodium tungstate solution, and calculate the recovery rate.

[0038] Example 1

[0039] The waste tungsten powder material (with a converted WO3 content of 85.2%) was ground fine, passed through a 40-mesh sieve, and 100 g was weighed and put into a corundum crucible. The mass ratio of acid to material was controlled at 1.5, and concentrated sulfuric acid with a mass fraction of 98% was added and mixed evenly with the waste tungsten powder material. It was placed in a vertical furnace, heated to 180 °C, calcined for 150 min, then the heating was stopped, and it was naturally cooled to below 100 °C and taken out. 2 L of water was added for leaching, and solid-liquid separation was carried out. Metals such as Zn, Fe, and Al formed corresponding sulfates and entered the solution. The solid obtained was tungsten carbide in the waste tungsten powder material and tungstic acid solid formed by the oxidation of tungsten to WO3 and its reaction with the acid. This tungstic acid solid was dissolved with a 300 g / L sodium hydroxide solution to obtain 1 L of sodium tungstate solution and a small amount of waste residue. The WO3 concentration in the sodium tungstate solution was detected to be 84.8 g / L, and the recovery rate was calculated to be 99.5%.

[0040] Example 2

[0041] The waste tungsten powder material (with a converted WO3 content of 81.4%) was ground fine, passed through a 40-mesh sieve, and 100 g was weighed and put into a corundum crucible. The mass ratio of acid to material was controlled at 4, and concentrated sulfuric acid with a mass fraction of 98% was added and mixed evenly with the waste tungsten powder material. It was placed in a vertical furnace, heated to 300 °C, calcined for 100 min, then the heating was stopped, and it was naturally cooled to below 100 °C and taken out. 2 L of water was added for leaching, and solid-liquid separation was carried out. Metals such as Zn, Fe, and Al formed corresponding sulfates and entered the solution. The solid obtained was tungsten carbide in the waste tungsten powder material and tungstic acid solid formed by the oxidation of tungsten to WO3 and its reaction with the acid. This tungstic acid solid was dissolved with a 300 g / L sodium hydroxide solution to obtain 1 L of sodium tungstate solution and a small amount of waste residue. The WO3 concentration in the sodium tungstate solution was detected to be 81.1 g / L, and the recovery rate was calculated to be 99.6%.

[0042] Example 3

[0043] The waste tungsten powder material (with a converted WO3 content of 75.1%) was ground fine, passed through a 40-mesh sieve, and 100 g was weighed and put into a corundum crucible. The mass ratio of acid to material was controlled at 2.5, and concentrated sulfuric acid with a mass fraction of 98% was added and mixed evenly with the waste tungsten powder material. It was placed in a vertical furnace, heated to 250 °C, calcined for 120 min, then the heating was stopped, and it was naturally cooled to below 100 °C and taken out. 2 L of water was added for leaching, and solid-liquid separation was carried out. Metals such as Zn, Fe, and Al formed corresponding sulfates and entered the solution. The solid obtained was tungsten carbide in the waste tungsten powder material and tungstic acid solid formed by the oxidation of tungsten to WO3 and its reaction with the acid. This tungstic acid solid was dissolved with a 300 g / L sodium hydroxide solution to obtain 1 L of sodium tungstate solution and a small amount of waste residue. The WO3 concentration in the sodium tungstate solution was detected to be 74.9 g / L, and the recovery rate was calculated to be 99.7%.

[0044] Comparative Example 1

[0045] The waste tungsten powder of Example 1 was ground fine, passed through a 40-mesh sieve, and then 100 g was weighed and spread out flat. It was put into a muffle furnace and calcined at 800 °C. During the calcination, the air circulation in the furnace was ensured to make the material fully contact with the air. After calcining for 4 h, the material was taken out and put into 1 L of aqueous solution. 500 g of NaOH was added, and it was heated to 95 °C and stirred for reaction for 2 h. Then, solid-liquid separation was carried out to obtain a high-alkali sodium tungstate solution and waste residue. After the waste residue was washed and dried, its weight was 45.1 g. The tungsten content in the residue was detected to be 11.7%, and the recovery rate was 92.2%.

[0046] Comparative Example 2

[0047] The waste tungsten powder (with a WO3 content of 85.2% after conversion, the same powder as in Example 1) was ground fine, passed through a 40-mesh sieve, and then 100 g was weighed and spread out flat. It was put into a muffle furnace and calcined at 800 °C. During the calcination, the air circulation in the furnace was ensured to make the material fully contact with the air. After calcining for 4 h, the material was taken out and put into 1 L of concentrated sulfuric acid with a mass fraction of 98%. It was heated to 95 °C and stirred for reaction for 2 h. Then, solid-liquid separation was carried out. The obtained solid was tungstic acid solid and a small amount of waste residue. After this solid was dissolved with a 300 g / L sodium hydroxide solution, 1 L of sodium tungstate solution and a small amount of waste residue were obtained. The WO3 concentration in the sodium tungstate solution was detected to be 79.5 g / L, and the calculated recovery rate was 93.4%.

[0048] It can be seen from the comparison between Example 1 and Comparative Examples 1-2 that due to the existence of antioxidant substances and coatings in the hard alloy waste, such as nickel, etc., it will hinder the contact and oxidation of tungsten in the hard alloy waste with oxygen. Therefore, the calcination temperature is very high, usually above 800 °C. And due to the existence of antioxidant substances, even at a high temperature above 800 °C, the oxidation of tungsten is not complete. Even when leaching with hot concentrated sulfuric acid later, if the conventional treatment temperature of hot concentrated sulfuric acid is adopted, it is still impossible to completely oxidize the tungsten or tungsten carbide in the hard alloy waste.

[0049] The present application can realize the calcination reaction at a lower temperature by heating and oxidizing with concentrated sulfuric acid. On the one hand, the acid can corrode antioxidant substances such as nickel in the waste, so that tungsten can be fully oxidized; more notably, when the temperature is above 180 °C, it is found through experiments that the tungsten carbide and tungsten in the waste tungsten powder can be completely oxidized to WO3 and further react with the acid to obtain tungstic acid solid, and the recovery rate is as high as over 99%; the technical solution provided by the present application realizes low-temperature calcination, and has the effects of significantly improving the oxidation rate of tungsten and increasing the recovery rate.

[0050] In summary, compared with the prior art, the method for treating waste tungsten carbide powder provided by the present invention can strengthen the oxidation reaction by roasting waste materials in concentrated sulfuric acid at low temperature, avoiding the defects of high energy consumption and low recovery rate in the traditional high-temperature air roasting process, and having the advantages of short process, low energy consumption and high recovery rate.

[0051] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved only in one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be regarded as a limitation to that claim.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating waste tungsten powder of cemented carbide, characterized in that it includes the following steps: Mix the waste tungsten powder of cemented carbide with an acidic oxidant to form a slurry, and then calcine at a temperature above 180°C and below 300°C to obtain an oxidized calcined material; Immerse the oxidized calcined material in water, stir and separate to obtain tungstic acid solid.

2. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the proportion of tungsten content in the waste tungsten powder of cemented carbide is above 70%.

3. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the cobalt and nickel content in the waste tungsten powder of cemented carbide is 1% - 2%, and the silicon content in the waste tungsten powder of cemented carbide is 5% - 10%.

4. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the particle size of the waste tungsten powder of cemented carbide is between 30 mesh and 50 mesh.

5. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the mass ratio of the acidic oxidant to the waste tungsten powder is 1.5 - 4.0:1.

0.

6. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the acidic oxidant is an acidic oxidant with an oxidizing property greater than or equal to concentrated sulfuric acid with a mass fraction of more than 98%.

7. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the acidic oxidant is concentrated sulfuric acid with a mass fraction of more than 98%, and the calcination time is 100 - 150 min.

8. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the solid-liquid ratio of water to the oxidized calcined material is 3 - 6.

9. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the stirring temperature is 0 - 100°C, and the stirring time is 60 - 120 min.

10. The method for treating waste tungsten powder of cemented carbide according to claim 1, characterized in that the separation is solid-liquid separation.

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