Method for treating hard alloy waste tungsten powder

Abstract

The invention belongs to the field of energy and environmental protection, and discloses a method for treating hard alloy waste tungsten powder, which comprises the following steps: mixing the hard alloy waste tungsten powder with high-concentration alkali with the mass percent concentration of 75-85%, introducing oxygen, and reacting to obtain reaction feed liquid; and separating the reaction feed liquid to obtain a sodium tungstate solution and waste residues. According to the method, tungsten in the hard alloy waste tungsten powder can be efficiently recycled while low cost and operation convenience are kept, and therefore cyclic utilization and sustainable development of resources are powerfully promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of tungsten resource recycling and utilization, and specifically relates to a method for treating waste tungsten powder of cemented carbide. Background Art

[0003] Due to the high hardness, high density and difficulty in being dissolved by common inorganic acids and alkalis of cemented carbide. Currently, the main methods for recycling cemented carbide are: zinc melting method, high-temperature treatment method, pyrolysis sintering method, mechanical crushing method, chemical treatment method, electrolysis method, and methods such as leaching with high-pressure oxygen, ammonia water or ammonium solution, carbonyl compound method and sublimation of tungsten trioxide with water vapor. However, each of these methods has its own advantages and disadvantages. The zinc melting method has a simple process, but it is easy to introduce impurities, has a low recovery rate and high energy consumption. More critically, the ratio control of zinc to cemented carbide needs to be extremely precise. If the amount of zinc is insufficient, the alloy is difficult to completely melt and disperse, while if the zinc is excessive, it will remain in the recovered product, damaging its performance. This method is more suitable for cemented carbide with a cobalt content of less than 12%. The electrochemical method is more effective for alloys with a cobalt content greater than 10%, but corrosive chemical agents need to be used during the recovery process, and it is easily affected by surface passivation, resulting in a slow reaction rate. Although the mechanical crushing method has a simple process, due to the high hardness and density of cemented carbide, the crushing is extremely difficult, and impurities are easily introduced during the process. Although the acid leaching method is feasible, the subsequent regeneration process is long, costly, and harmful gases will be generated. The current 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, due to the coatings or other antioxidant substances added during the production process of cemented carbide, the oxidation process is difficult to be thorough. At the same time, high-temperature (above 800°C) oxidative roasting is likely to cause the melting of silicon-containing phases, resulting in furnace caking, affecting the roasting operation, and thus restricting the effective recovery of waste materials. In addition, this method also has problems such as incomplete tungsten recovery, high energy consumption and waste gas pollution.

[0004] Therefore, it is particularly important to develop a method for treating waste tungsten powder of cemented carbide with a simple process, low energy consumption and high recovery rate. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for treating waste tungsten powder of cemented carbide, which can achieve efficient recovery of tungsten in waste tungsten powder of cemented carbide while maintaining low cost and simplicity of operation, thereby strongly promoting the recycling and sustainable development of resources.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for treating waste tungsten powder of cemented carbide, comprising the following steps:

[0008] Mix the cemented carbide waste tungsten powder with a high-concentration alkali having a mass percentage concentration of 75%-85%, and then react after introducing oxygen to obtain a reaction liquor; separate the reaction liquor to obtain a sodium tungstate solution and waste residue.

[0009] In some embodiments, the particle size of the cemented carbide waste tungsten powder is above 40 mesh.

[0010] In some embodiments, the high-concentration alkali is at least one of sodium hydroxide or potassium hydroxide.

[0011] In some embodiments, the volume-mass ratio of the high-concentration alkali to the cemented carbide waste tungsten powder is 8 mL / g - 15 mL / g.

[0012] In some embodiments, the reaction pressure is 0.5 MPa - 1.4 MPa.

[0013] In some embodiments, the reaction temperature is 220°C - 250°C.

[0014] In some embodiments, the reaction time after introducing oxygen is 360 min - 480 min.

[0015] In some embodiments, the oxygen purity is above 99.9%, and the oxygen flow rate is 1.5 L / min - 2 L / min.

[0016] In some embodiments, the separation is solid-liquid separation, and water is added to the reaction liquor before the solid-liquid separation.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0018] By using a high-concentration alkali with a mass percentage concentration of 75%-85% to treat the cemented carbide waste tungsten powder, and utilizing the enhanced oxidation effect of the high-concentration alkali, the present invention overcomes the defects of high energy consumption and low recovery rate in the traditional high-temperature roasting process, realizes the efficient recovery of tungsten with a simple process and low energy consumption, and the tungsten recovery rate can reach 99.8%. Specific Embodiments

[0019] The present invention provides a method for treating cemented carbide waste tungsten powder, comprising the following steps:

[0020] Mix the cemented carbide waste tungsten powder with a high-concentration alkali having a mass percentage concentration of 75%-85%, and then react after introducing oxygen to obtain a reaction liquor; separate the reaction liquor to obtain a sodium tungstate solution and waste residue.

[0021] Specifically, after the hard alloy waste tungsten powder is ground to more than 40 meshes, it is mixed with at least one of high-concentration sodium hydroxide or potassium hydroxide with a mass percentage concentration of 75%-85% according to the volume-mass ratio of the high-concentration alkali to the hard alloy waste tungsten powder of 8 mL / g - 15 mL / g. Then, under the conditions of a reaction pressure of 0.5 MPa - 1.4 MPa, a stirring speed of 700 r / min - 900 r / min, a reaction temperature of 220°C - 250°C, an oxygen purity of more than 99.9%, and an oxygen flow rate of 1.5 L / min - 2 L / min, the reaction continues for 360 - 480 min to obtain a reaction liquor. Subsequently, the reaction liquor is diluted with water and then subjected to solid-liquid separation to obtain a high-alkali sodium tungstate solution and waste residue.

[0022] It should be noted that the volume-mass ratio of the high-concentration alkali used in the present invention to achieve efficient recovery of tungsten sources in hard alloy waste tungsten powder is 8 mL / g - 15 mL / g, and the reaction temperature is 220°C - 250°C. When the ratio is lower than 8 mL / g or the reaction temperature is lower than 220°C, there will be a problem that the reaction is incomplete and part of the tungsten cannot be oxidized; when the ratio is higher than 15 mL / g or the reaction temperature is higher than 250°C, it will cause waste of energy and increase the recovery cost.

[0023] It should be noted that the present invention can achieve efficient recovery of tungsten sources in hard alloy waste tungsten powder at a relatively low pressure (0.5 MPa - 1.4 MPa) and a relatively low temperature (220°C - 250°C) by using a high-concentration alkali with a mass percentage concentration of 75%-85%. If a high-concentration alkali with a mass percentage concentration of 75%-85% is not used and only the temperature is increased, the reaction time is prolonged, or both the temperature and the reaction time are increased simultaneously, efficient recovery of tungsten cannot be achieved at a relatively low pressure (0.5 MPa - 1.4 MPa). Among them, the high-concentration alkali with a mass percentage concentration of 75%-85% can exhibit some characteristics similar to those of sub-molten salts. Its functions are as follows: on the one hand, it can greatly increase the activity of the reactants and simultaneously provide HO2 - 、O2 - 、O 2- 、O2 2- and other active oxygen anions, which greatly strengthen the oxidation of tungsten powder or tungsten carbide powder in the waste tungsten powder, improve the reaction rate and conversion rate, and enable a relatively high reaction efficiency to be achieved at a relatively low temperature; on the other hand, the high-concentration alkali with a mass percentage concentration of 75%-85% is a highly mobile ionized solvent, which can strengthen the mass transfer of oxygen, making it easier for oxygen to contact the reactants, so that the reaction can be achieved at a relatively low pressure. Compared with the gas-solid reaction of traditional roasting, the reaction mass transfer is strengthened, the reaction efficiency is improved, and the energy consumption is lower.

[0024] In addition, the reason why the particle size of the cemented carbide waste tungsten powder in the present invention needs to be ground to more than 40 mesh is that the particle size of the waste tungsten powder is crucial for subsequent treatment. When the particle size is large, the tungsten inside the particle size is not easily contacted with the solution, which will affect the tungsten content in the slag.

[0025] In the present invention, the particle size of the cemented carbide waste tungsten powder needs to be ground to more than 40 mesh, which means that the particle size of the cemented carbide waste tungsten powder needs to be ground to not more than 0.425 mm.

[0026] The reason for adding water before the solid-liquid separation of the reaction feed liquid in the present invention is that the alkalinity of the reaction feed liquid is too high. When the alkalinity is too high, the feed liquid is not easily filtered, and the moisture content of the filtered slag is high. Therefore, it is necessary to dilute the reaction feed liquid with water before the solid-liquid separation of the reaction feed liquid.

[0027] The method provided by the present invention is applicable to cemented carbide waste tungsten powders with various cobalt contents and tungsten contents.

[0028] In the present invention, unless otherwise specifically stated, the contents of all substances mentioned refer to their mass percentage contents.

[0029] The calculation method of the tungsten recovery rate in the present invention is as follows:

[0030] Tungsten recovery rate (%) = 1 - weight of waste residue × tungsten content in the waste residue detected / (weight of waste tungsten powder × WO3 content of waste tungsten powder)

[0031] The present invention will be further described in detail with specific examples and comparative examples. The following examples and comparative examples can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

[0032] Example 1:

[0033] This example provides a method for treating cemented carbide waste tungsten powder, including the following steps:

[0034] After grinding the waste tungsten powder (with a WO3 content of 83.1% after conversion) and passing it through a 40-mesh sieve, 100 g was weighed and put into a reaction kettle. 800 mL of NaOH solution was added, the NaOH concentration was controlled at 85%, the stirring speed was 900 r / min, it was heated to 250 °C, oxygen was introduced, the oxygen flow rate was 2 L / min, and the reaction was carried out under heat preservation for 480 min, and the reaction pressure was 1.2 MPa. After the reaction ended, 2 L of water was added to dilute the reaction feed liquid, and then solid-liquid separation was carried out to obtain a high-alkali sodium tungstate solution and waste residue. The alkali concentration of the high-alkali sodium tungstate solution was 232.6 g / L. The waste residue was washed, dried, and weighed to be 31.1 g. The tungsten content in the detected slag was 0.47%, and the tungsten recovery rate was 99.8%.

[0035] Example 2:

[0036] Compared with Example 1, the concentration of NaOH used was 75%, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 207.3 g / L. After washing and drying the waste residue, its weight was 31.5 g. The tungsten content in the detected residue was 0.54%, and the tungsten recovery rate was 99.7%.

[0037] Example 3:

[0038] Compared with Example 1, the concentration of the NaOH solution used was 80%, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 218.3 g / L. After washing and drying the waste residue, its weight was 31.2 g. The tungsten content in the detected residue was 0.51%, and the tungsten recovery rate was 99.8%.

[0039] Example 4:

[0040] Compared with Example 1, the heating temperature was 220 °C, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 235.1 g / L. After washing and drying the waste residue, its weight was 32.6 g. The tungsten content in the detected residue was 0.61%, and the tungsten recovery rate was 99.7%.

[0041] Example 5:

[0042] Compared with Example 1, the heating temperature was 235 °C, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 233.7 g / L. After washing and drying the waste residue, its weight was 31.8 g. The tungsten content in the detected residue was 0.41%, and the tungsten recovery rate was 99.8%.

[0043] Example 6:

[0044] Compared with Example 1, the volume of the NaOH solution used was 1000 mL, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 273.8 g / L. After washing and drying the waste residue, its weight was 30.8 g. The tungsten content in the detected residue was 0.42%, and the tungsten recovery rate was 99.8%.

[0045] Example 7:

[0046] Compared with Example 1, the volume of the NaOH solution used was 1500 mL, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 356.1 g / L. After washing and drying the waste residue, its weight was 30.7 g. The tungsten content in the detected residue was 0.42%, and the tungsten recovery rate was 99.8%.

[0047] Example 8:

[0048] This example provides a method for treating waste tungsten powder of cemented carbide, including the following steps:

[0049] The waste tungsten powder material (with a converted WO3 content of 76.4%) was ground fine, screened through a 40-mesh sieve, and then 100 g was weighed and put into an atmospheric pressure reactor. 1000 mL of KOH solution was added, the KOH concentration was controlled at 75%, the stirring speed was 700 r / min, it was heated to 220 °C, oxygen was introduced, the oxygen flow rate was 1.5 L / min, and the reaction was carried out under insulation for 360 min. After the reaction ended, the reaction liquid was diluted with 2 L of water, and then solid-liquid separation was carried out to obtain a high-alkali sodium tungstate solution and waste residue. The alkali concentration of the high-alkali sodium tungstate solution was 238.1 g / L, the waste residue was washed, dried, and weighed to be 30.6 g. The tungsten content in the detected residue was 0.41%, and the tungsten recovery rate was 99.8%.

[0050] Example 9:

[0051] This example provides a method for treating waste tungsten powder materials of cemented carbide, including the following steps:

[0052] The waste tungsten powder material (with a converted WO3 content of 80.7%) was ground fine, screened through a 40-mesh sieve, and then 100 g was weighed and put into an atmospheric pressure reactor. 1500 mL of NaOH solution was added, the NaOH concentration was controlled at 80%, the stirring speed was 800 r / min, it was heated to 240 °C, oxygen was introduced, the oxygen flow rate was 1.8 L / min, and the reaction was carried out under insulation for 400 min. After the reaction ended, the reaction liquid was diluted with 2 L of water, and then solid-liquid separation was carried out to obtain a high-alkali sodium tungstate solution and waste residue. The alkali concentration of the high-alkali sodium tungstate solution was 334.9 g / L, the waste residue was washed, dried, and weighed to be 31.5 g. The tungsten content in the detected residue was 0.49%, and the tungsten recovery rate was 99.8%.

[0053] Example 10:

[0054] Compared with Example 1, the concentration of NaOH used was 90%, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 246.9 g / L, the waste residue was washed, dried, and weighed to be 30.8 g. The tungsten content in the detected residue was 0.39%, and the tungsten recovery rate was 99.8%. Comparative Example 1:

[0055] Compared with Example 1, the concentration of NaOH used was 70%, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 190.1 g / L, the waste residue was washed, dried, and weighed to be 38.2 g. The tungsten content in the detected residue was 5.6%, and the tungsten recovery rate was 96.8%. Comparative Example 2:

[0056] Compared with Example 1, the waste tungsten powder material (with a converted WO3 content of 83.1%) was ground fine and screened through a 35-mesh sieve, and other conditions remained unchanged. The alkali concentration of the high-alkali sodium tungstate solution was measured to be 232.6 g / L, the waste residue was washed, dried, and weighed to be 32.1 g. The tungsten content in the detected residue was 1.83%, and the tungsten recovery rate was 99.1%.

[0057] Comparative Example 3:

[0058] Compared with Example 1, after the same waste tungsten powder was ground and sieved through a 40-mesh sieve, 100 g was weighed and spread out, then put into a muffle furnace and calcined at 800 °C. During the calcination, the air in the furnace was ensured to circulate so that the material could fully contact with the air. After 4 hours of calcination, the material was taken out and put into 2 L of aqueous solution. 500 g of NaOH was added, and after heating to 95 °C and stirring for reaction for 2 hours, solid-liquid separation was carried out to obtain a high-alkali sodium tungstate solution and waste residue. The alkali concentration of the high-alkali sodium tungstate solution was 473.5 g / L. After the waste residue was washed and dried, its weight was 46.7 g. The tungsten content in the detected slag was 10.7%, and the tungsten recovery rate was 92.4%.

[0059] It can be seen from Example 1, Example 10 and Comparative Example 1 that when the alkali concentration is lower than 75%, the tungsten recovery rate is relatively low, while when the alkali concentration is higher than 85%, the tungsten recovery rate basically remains unchanged. Considering tungsten recovery and effective utilization of resources comprehensively, the alkali concentration of 75%-85% is adopted in this application. By comparing Example 1 and Comparative Example 2, it is found that when the particle size of the waste tungsten powder is below 40 mesh, the tungsten recovery rate is relatively low, and the tungsten in the waste tungsten powder with a particle size below 40 mesh is not easy to contact with the solution, thus affecting the tungsten content in the slag. In addition, by comparing the tungsten recovery rates of Example 1 and Comparative Example 3, it is proved that the method used in the present invention is more conducive to the recovery of tungsten in the waste tungsten powder compared with the currently commonly used redox method (a method of oxidizing tungsten carbide powder or tungsten powder by calcining in the air using a rotary kiln, etc. and then recovering by alkali leaching).

[0060] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes 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 hard alloy waste tungsten powder with a high-concentration alkali with a mass percentage concentration of 75%-85%, and then react after introducing oxygen to obtain a reaction liquor; After separating the reaction liquor, a sodium tungstate solution and waste residue are obtained.

2. The method for treating hard alloy waste tungsten powder according to claim 1, wherein The particle size of the hard alloy waste tungsten powder is above 40 mesh.

3. The method for processing hard alloy waste tungsten powder materials according to claim 1, characterized in that, The high-concentration alkali is at least one of sodium hydroxide or potassium hydroxide.

4. The method for processing waste tungsten carbide powder according to claim 1, wherein The volume-mass ratio of the high-concentration alkali to the hard alloy waste tungsten powder is 8 mL / g - 15 mL / g.

5. The method for treating hard alloy waste tungsten powder according to claim 1, characterized in that, The reaction pressure is 0.5 MPa - 1.4 MPa.

6. The method for treating hard alloy waste tungsten powder materials according to claim 1, wherein The reaction temperature is 220°C - 250°C.

7. The method for treating hard alloy waste tungsten powder according to claim 1, characterized in that, The reaction time after introducing oxygen is 360 min - 480 min.

8. The method for treating hard alloy waste tungsten powder according to claim 1, characterized in that, The purity of the oxygen is above 99.9%, and the oxygen flow rate is 1.5 L / min - 2 L / min.

9. The method for treating hard alloy waste tungsten powder according to claim 1, characterized in that, The separation is solid-liquid separation, and water is added to the reaction liquor before the solid-liquid separation.