A method for producing an oxide from tungsten-containing waste material using a kiln

Abstract

The present application relates to the technical field of tungsten waste recovery, and particularly relates to a method for preparing oxide from tungsten-containing waste by using a kiln. The method for preparing oxide from tungsten-containing waste by using a kiln is as follows: tungsten waste is placed in a kiln and rapidly heated to 750-1250 DEG C, oxygen is introduced into the kiln, air in the kiln is exhausted, and oxygen is continuously introduced, so that the tungsten waste is calcined and oxidized at 750-1250 DEG C for 2-4 hours in an oxygen atmosphere, after the calcination and oxidation reaction is completed, the kiln stops electric heating, oxygen is continuously introduced, and the kiln is opened after being cooled to 100 DEG C in the oxygen atmosphere, and the tungsten waste is cooled to room temperature, ball milling and gravity screening are performed on the calcined tungsten waste to obtain high-purity tungsten oxide powder. The tungsten waste recovery process provided by the present application has small investment, low consumption cost, low manual operation difficulty, and the equipment is easy to realize automation, the process flow is short, the metal recovery rate is high, and the tungsten waste is suitable for large-scale recovery.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of tungsten waste recovery, in particular to a method for preparing tungsten-containing waste into an oxide by using a kiln. BACKGROUND

[0002] Metal tungsten has the advantages of high melting point, high hardness, high strength, high-temperature oxidation resistance, corrosion resistance, creep resistance, low thermal expansion coefficient, good electrical conductivity and thermal conductivity, and is widely used in alloy manufacturing, photovoltaic industry, electronic industry, military equipment, chemical catalysis, medical equipment and other fields.

[0003] In the process of tungsten material processing, tungsten-containing waste is inevitably produced, which mainly includes tungsten wire after nickel removal, substandard waste tungsten wire in the production process, and tungsten-nickel diamond wire produced in the photovoltaic industry. The tungsten content in the tungsten-containing waste is high, and its recovery value is high. Tungsten waste recovery has important significance and value. Through the recovery of waste tungsten products, not only the exploitation of primary tungsten resources can be reduced to protect limited natural resources, but also the pollution of waste to the environment can be reduced, and the risk of ecological damage can be reduced.

[0004] At present, the recovery process of the wire-shaped tungsten-containing waste produced in the tungsten material processing link in the existing industrial technology mainly uses the sulfuric acid roasting-water leaching-calcination method to prepare tungsten oxide. Although this method can extract tungsten oxide with high purity from the tungsten-containing waste, the operation of the above-mentioned process is complex and difficult, industrial waste is produced in the recovery process, the environmental protection performance is poor, and the recovery cost of the tungsten-containing waste is high. Therefore, the inventor provides a method for preparing tungsten-containing waste into an oxide by using a kiln. SUMMARY

[0005] In order to solve the problems of the existing technology, such as complex operation, high difficulty, generation of industrial waste in the recovery process, poor environmental protection performance, and high recovery cost of tungsten-containing waste, the application provides a method for preparing tungsten-containing waste into an oxide by using a kiln, which has small investment, low consumption cost, low manual operation difficulty, short process flow, high recovery rate, good environmental protection performance, and is suitable for large-scale recovery of tungsten waste.

[0006] The method for preparing tungsten-containing waste into an oxide by using a kiln provided by the application is realized by the following technical scheme:

[0007] A method for preparing tungsten-containing waste into an oxide by using a kiln, the steps are as follows:

[0008] Step one, place the tungsten waste on the silicon carbide shelf in the kiln, and close the kiln;

[0009] Step two, turn on the electric heating to quickly raise the temperature in the kiln to 750-1250 DEG C;

[0010] Step three, oxygen is introduced into the kiln, and the air in the kiln is exhausted, oxygen is continuously introduced, the electric heating power of the kiln is controlled under the oxygen atmosphere, the temperature in the kiln is maintained at 750-1250℃, and the calcination oxidation reaction is carried out at 750-1250℃ for 2-6h;

[0011] Step four, after the calcination oxidation reaction is completed, stop the electric heating, continuously introduce oxygen, and after the temperature in the kiln is reduced to 100-200℃ under the oxygen atmosphere, open the kiln and naturally cool to room temperature to obtain calcined tungsten waste;

[0012] Step five, the calcined tungsten waste in step four is ball milled and gravity screened to obtain high-purity tungsten oxide powder.

[0013] The present application is particularly suitable for tungsten-containing waste materials such as nickel-removed tungsten wire, waste tungsten wire generated during production, and tungsten-nickel diamond wire generated in the photovoltaic industry, etc. The tungsten-containing waste materials are prepared into tungsten oxide by the method of preparing oxides from tungsten-containing waste materials in a kiln, realizing the large-scale recovery of tungsten waste materials.

[0014] In the present method, the tungsten-containing waste materials are placed on a high-temperature-resistant waste material placing rack. The high-temperature-resistant silicon carbide waste material placing rack can provide good support for the bundled and stranded tungsten-containing waste materials, so that the bundled and stranded tungsten-containing waste materials can still maintain the state of being bundled and stranded after calcination, thereby reducing the generation of a large amount of dust during calcination and taking out, and reducing the adverse effects generated during the preparation of tungsten oxide.

[0015] In the present method, the tungsten-containing waste materials are calcined by introducing oxygen into the kiln. The kiln is a relatively closed space, which can make the calcination more complete, reduce the heat energy required for calcination, and improve the calcination efficiency. At the same time, the introduced oxygen can be better retained in the kiln, so that the oxygen can be well combined with the tungsten-containing waste materials under the condition of high-temperature calcination, and the combination of tungsten itself and oxygen can also release a large amount of heat, which can fully promote the calcination. The pre-set temperature range and pre-set time range are used as the calcination conditions to ensure that the tungsten-containing waste materials can achieve the expected calcination effect, and the recovery efficiency of the tungsten waste materials is effectively improved.

[0016] After the calcined tungsten-containing waste materials are ball milled, powdery oxides can be obtained. Then, the non-oxide impurities with relatively low density are screened by gravity screening. The powder screened by gravity screening is high-purity tungsten oxide powder (a small amount of tungsten particles). The high-purity tungsten oxide powder is subsequently calcined and reduced in hydrogen or carbon monoxide to obtain high-purity tungsten particles.

[0017] In summary, the tungsten waste material recovery process provided by the present application has the advantages of small investment, low consumption cost, low manual operation difficulty, easy automation of equipment, short process flow, high metal recovery rate, and is suitable for large-scale recovery of tungsten waste materials.

[0018] Preferably, the volume of the kiln is 4-8.0 m³. 3 The load mass of tungsten waste on the silicon carbide placement rack in the kiln is 1.5-4.0t; the heating rate of the kiln is 0.1-8.33℃ / min, and the output power is 0-450kW.

[0019] Preferably, the elemental composition of the tungsten waste in step one includes tungsten and M, wherein M is one or more combinations of C, N, S, Si, Ni, Fe, Cu, Co, Ag, Ti, Ta, Ru, Rh, Zr, Mo, Al, Hf, Ir, Te, and Ga.

[0020] By adopting the above technical solution, various tungsten alloy wastes can be recycled.

[0021] Preferably, before step one, elemental analysis is performed on the tungsten waste to be recycled. This analysis reveals the content of tungsten and methyl oxidase (M) in the waste. The calcination oxidation reaction equation for tungsten is 2W + 3O₂ = 2WO₃; the calcination oxidation reaction equation for methyl oxidase is XM + 0.5Y*O₂ = M. X O Y The amount of oxygen required for the complete calcination and oxidation of tungsten and M in tungsten waste was calculated using the calcination and oxidation reaction equation of tungsten and M. 标 In steps three and four, the total mass M of oxygen input into the kiln is... 实 The amount of oxygen used by the complete calcination and oxidation of tungsten and M in tungsten waste 标 The mass ratio is (99-104):100.

[0022] By adopting the above technical solutions, the recovery rate of tungsten metal can be effectively improved, and the reaction process can be better controlled, thereby optimizing the calcination process, reducing overall power consumption, and lowering the recycling cost of tungsten waste.

[0023] Preferably, in step three, oxygen is introduced into the kiln to purge the air inside the kiln. Oxygen is continuously introduced, and the pressure inside the kiln is maintained at 100-102 kPa. Under the oxygen atmosphere, the electric heating power of the kiln is controlled to maintain the temperature inside the kiln at 750-1250°C. The calcination oxidation reaction is carried out at 750-1250°C for 2-6 hours.

[0024] Preferably, in step four, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, the pressure inside the kiln is maintained at 100-102 kPa, and after the temperature inside the kiln drops to 100°C in the oxygen atmosphere, the kiln is opened and allowed to cool naturally to room temperature, thus obtaining calcined tungsten waste.

[0025] Preferably, in step two, the kiln is electrically heated at a rate of 7.5-8.2℃ / min, so that the temperature inside the kiln rises rapidly to 750-1250℃.

[0026] Further preferably, in the step two, the kiln is electrically heated at a heating rate of 7.5-8.2℃ / min to rapidly raise the temperature in the kiln to 950-1050℃; in the step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and the oxygen is continuously introduced to maintain the pressure in the kiln at 100-102KPa, and the electric heating power of the kiln is controlled at 2.0-3.5kW in the oxygen atmosphere to maintain the temperature in the kiln at 950-1250℃, and the calcination oxidation reaction is performed at 950-1250℃ for 4.0h.

[0027] By adopting the above technical solution, the recovery rate of tungsten metal is effectively improved, and the electric energy consumption of the kiln in the process of oxidizing and calcining the tungsten waste material is reduced, thereby the recovery cost of the tungsten waste material can be optimized.

[0028] Preferably, in the step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and the oxygen is continuously introduced to maintain the pressure in the kiln at 100-102KPa, and the electric heating power of the kiln is controlled at 1.0-3.5kW in the oxygen atmosphere to maintain the temperature in the kiln at 750-1250℃ to perform the calcination oxidation reaction, until the cumulative oxygen V 时 introduced into the kiln in the step three is equal to 0.70-0.90 times of the oxygen consumption M 标 resulted from the complete calcination oxidation of tungsten and M in the tungsten waste material.

[0029] Preferably, in the step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and the oxygen is continuously introduced to maintain the pressure in the kiln at 100-102KPa, and the electric heating power of the kiln is controlled at 1.0-3.5kW in the oxygen atmosphere to maintain the temperature in the kiln at 750-1250℃ to perform the calcination oxidation reaction, until the cumulative oxygen V 时 introduced into the kiln in the step three is equal to 0.75-0.80 times of the oxygen consumption M 标 resulted from the complete calcination oxidation of tungsten and M in the tungsten waste material.

[0030] By controlling the cumulative oxygen V 时 introduced into the kiln, the calcination procedure is optimized, the time for oxidizing and calcining the tungsten waste material is shortened under the premise of ensuring a high recovery rate of tungsten metal, thereby the electric energy consumption of the kiln in the process of oxidizing and calcining the tungsten waste material can be effectively reduced, and the recovery cost of the tungsten waste material can be optimized.

[0031] Preferably, in the step four, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, the oxygen is continuously introduced, and the pressure in the kiln is maintained at 100-102KPa, when the oxygen introduction amount is ≤50sccm, the emptying pipe is opened after 0.5-1h, low-temperature nitrogen is introduced to replace the oxygen, and the nitrogen flow rate is 0.2-0.6m 3 / min, so that the temperature in the kiln is rapidly reduced to 100 DEG C, and then the kiln is opened for natural cooling to room temperature, and the calcined tungsten waste material is obtained.

[0032] By the way of rapid cooling of low-temperature nitrogen, the particle size of the ball-milled powder can be refined, and tungsten particles and tungsten oxide can be screened out by gravity, and the screened material is non-tungsten metal and its oxide, so that the tungsten metal recovery rate can be improved.

[0033] In summary, the application has the following advantages:

[0034] 1. The tungsten waste recovery process provided by the application has small investment, low total energy consumption and operation difficulty, short process flow, high metal recovery rate, and is easy to realize automation, and is suitable for large-scale recovery of tungsten waste.

[0035] 2. The device used in the application is a kiln, the volume of the kiln is six cubic meters, and two tons of tungsten waste can be treated, which is suitable for large-scale recovery of tungsten waste, thereby reducing the cost of tungsten waste recovery.

[0036] 3. The application of the kiln to prepare the tungsten-containing waste into an oxide is high-purity (≥99.5%) tungsten oxide prepared by calcining, ball-milling and gravity screening of the tungsten waste, which has relatively high application value and can be applied to the field of optoelectronic information, and can be used to produce electrochromic windows and other photoelectric products. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a temperature-time curve relationship diagram in the tungsten waste calcination process in the embodiment of the application. DETAILED DESCRIPTION

[0038] In order to further understand the creativity and technical progress of the application, the preferred embodiment of the application is discussed in detail below in combination with examples and comparative examples.

[0039] Embodiment: A method for preparing tungsten-containing waste into an oxide by using a kiln, comprising the following steps:

[0040] Step one, place the tungsten waste on the silicon carbide placing rack in the kiln, and close the kiln;

[0041] The volume of the kiln is 4.0-8.0 m 3 , the heating rate of the kiln is 0.1-8.33 DEG C / min, and the output power is 0-450 kW;

[0042] The load mass of the tungsten waste on the silicon carbide placing rack in the kiln is 1.5-3 t, and the preferred load mass is 2 t;

[0043] The method is suitable for the element composition of the tungsten waste material, which includes tungsten and M, M is at least one of C, N, S, Si, Ni, Fe, Cu, Co, Ag, Ti, Ta, Ru, Rh, Zr, Mo, Al, Hf, Ir, Te, Ga;

[0044] Preferably, before step one, element determination is performed on the tungsten waste material to be recycled, and the content of tungsten and M in the tungsten waste material to be recycled is known through the element determination, the calcination oxidation reaction equation of tungsten is 2W+3O2=2WO3, and the calcination oxidation reaction equation of M is XM+0.5Y*02=M X O Y The oxygen consumption M 标 resulted from the complete calcination oxidation of tungsten and M in the tungsten waste material is calculated through the calcination oxidation reaction equation of tungsten and M;

[0045] Step two, the kiln is electrically heated, and the temperature in the kiln is rapidly increased to 750-1250℃ at a heating rate of 7.5-8.2℃ / min;

[0046] Step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and the oxygen is continuously introduced, the electric heating power of the kiln is controlled under the oxygen atmosphere, the temperature in the kiln is maintained at 750-1250℃, and the calcination oxidation reaction is performed at 750-1250℃ for 2.0-6.0h;

[0047] Preferably, in step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and the oxygen is continuously introduced to maintain the pressure in the kiln at 100-102Kpa, the electric heating power of the kiln is controlled under the oxygen atmosphere, the temperature in the kiln is maintained at 950-1250℃, and the calcination oxidation reaction is performed at 950-1250℃ for 4h;

[0048] Or preferably, in step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and the oxygen is continuously introduced to maintain the pressure in the kiln at 100-102Kpa, the electric heating power of the kiln is controlled under the oxygen atmosphere, the temperature in the kiln is maintained at 750-1250℃, and the calcination oxidation reaction is performed until the cumulative oxygen V 时 introduced into the kiln in step three is equal to 0.65-0.90 times the oxygen consumption M 标 resulted from the complete calcination oxidation of tungsten and M in the tungsten waste material;

[0049] Further preferably, the temperature in the kiln is maintained at 750-1250℃ for the calcination oxidation reaction until the cumulative oxygen V 时 introduced into the kiln in step three is equal to 0.75-0.80 times the oxygen consumption M 标 resulted from the complete calcination oxidation of tungsten and M in the tungsten waste material;

[0050] Step four, after the calcination oxidation reaction is completed, the kiln stops electric heating, continues to input oxygen, maintains the pressure in the kiln at 100-102 KPa, and the temperature in the kiln is reduced to 100℃. After the kiln is opened, it is cooled to room temperature in the air cooling mode, and the calcined tungsten waste material is obtained.

[0051] Or preferably, step four, after the calcination oxidation reaction is completed, the kiln stops electric heating, continues to input oxygen, maintains the pressure in the kiln at 100-102 KPa, and the temperature in the kiln is reduced to 100℃. After the kiln is opened, it is cooled to room temperature in the air cooling mode, and the calcined tungsten waste material is obtained.

[0052] Or preferably, step four, after the calcination oxidation reaction is completed, the kiln stops electric heating, continues to input oxygen, maintains the pressure in the kiln at 100-102 KPa, and the temperature in the kiln is reduced to 100℃. After the kiln is opened, it is cooled to room temperature in the air cooling mode, and the calcined tungsten waste material is obtained. 3

[0053] The total mass M of oxygen input into the kiln in steps three and four 实 The mass ratio of the oxygen used for complete calcination oxidation of tungsten and M in the tungsten waste material is (99-104):100. 标 It should be noted that the total mass M of oxygen 实 is related to the calcination temperature, holding time, kiln pressure, and cooling mode.

[0054] Step five, the calcined tungsten waste material in step four is ball milled and gravity separated to obtain high-purity tungsten oxide powder.

[0055] Example 1: A method for preparing an oxide from tungsten-containing waste material using a kiln, comprising the following steps:

[0056] The tungsten waste material is a discarded tungsten-nickel diamond wire in the photovoltaic industry. Before the tungsten waste material is loaded into the silicon carbide holder in the kiln, the elements of the tungsten waste material are determined. The tungsten (W) in the recovered tungsten-nickel diamond wire is 91.78%, the nickel (Ni) is 7.15%, and the oxygen (O) is 0.85%. Through the element determination of the tungsten waste material, the content of tungsten and nickel in the tungsten waste material to be recovered is known. The calcination oxidation reaction equation of tungsten is 2W+3O2=2WO3; the calcination oxidation reaction equation of M is XM+0.5Y*02=M X O Y The amount of oxygen used for complete calcination oxidation of tungsten and nickel in the tungsten waste material is calculated by the calcination oxidation reaction equation of tungsten and nickel. 标 ​, 2 tons of tungsten nickel diamond wire discarded in the above photovoltaic industry needs the oxygen obtained by complete calcination oxidation M 标， M 标 == 32 * {【1.5 * 2 * 10 6 * 0.9178 / 183.84】+【0.5 * 2 * 10 6 * 0.0715 / 58.69】-【0.5 * 2 * 10 6 * 0.0085 / 32】} / 1000 = 509.75 kg.

[0057] The volume of the kiln used in the present application is 6.0m 3 , the tungsten waste load mass on the silicon carbide placement rack in the kiln is 2t, the output power is 0-450kW, and the kiln heating rate is 0.1-8.33℃ / min by controlling the output power;

[0058] Step one, place the tungsten waste in the kiln on the silicon carbide placement rack, close the kiln;

[0059] Step two, turn on the electric heating of the kiln, and make the temperature in the kiln rise rapidly to 750℃ at a rate of 8℃ / min;

[0060] Step three, open the exhaust pipe, introduce industrial oxygen into the kiln, exhaust the air in the kiln, close the exhaust pipe, continuously introduce industrial oxygen into the kiln, maintain the pressure in the kiln between 100-102Kpa, control the electric heating power of the kiln to be 1.5kW in the oxygen atmosphere, and the calcination oxidation reaction is 6h, the temperature in the kiln increases from the initial 750℃ to 879.6℃ after 6h due to the release of a large amount of heat by the reaction of tungsten and oxygen, and the amount of industrial oxygen introduced is 400.68kg;

[0061] Step four, after 6h of calcination oxidation reaction, stop the electric heating of the kiln, continue to introduce oxygen, maintain the pressure in the kiln between 100-102Kpa in the oxygen atmosphere, after 196min, it is observed that the oxygen flow is 42sccm (≤50sccm), at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the mass of industrial oxygen introduced into the kiln is 506.94kg, the oxygen is pressurized into the kiln until the pressure in the kiln reaches 120Kpa, then the oxygen input is stopped, and the temperature in the kiln decreases to 100℃, then the kiln is opened, and the air cooling method is used to reduce the temperature to room temperature, and the calcined tungsten waste is obtained;

[0062] Step five, place the calcined tungsten waste in step four in an industrial ball mill, use corundum grinding balls for ball milling, and ball mill at 240rpm for 0.5h to obtain a calcined powder with a particle size distribution of 27-81 microns (D 50 52 microns), and separate the ball-milled material in a gravity sieve machine for gravity screening, and screen out a calcined powder with a density of ≥7g / cm3 The powder obtained in the step 1 is calcined to obtain the high-purity tungsten oxide powder.

[0063] The pressure control method in the kiln in the step two is as follows: when the pressure sensor in the kiln detects that the pressure in the kiln is lower than 100 KPa, the pressure sensor and the electromagnetic valve on the oxygen input pipe are connected to the PLC chip, the feedback electric signal of the pressure sensor controls the electromagnetic valve on the oxygen input pipe to open, until the pressure sensor in the kiln detects that the pressure in the kiln is greater than or equal to 120 KPa, the feedback electric signal of the pressure sensor controls the electromagnetic valve on the oxygen input pipe to close.

[0064] The difference between the example 2 and the example 1 is that: in the step four, after the calcination and oxidation reaction for 6 hours, the kiln stops the electric heating, the oxygen is continuously input, the pressure in the kiln is maintained between 100-102 KPa under the oxygen atmosphere, after 196 minutes, it is observed that the oxygen input amount is 43 sccm (≤50 sccm), at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the cumulative mass of the industrial oxygen input into the kiln is 506.97 kg, the oxygen is input into the kiln in the pressurization mode, the pressure in the kiln is maintained between 115-120 KPa, under the oxygen atmosphere, the temperature in the kiln is reduced to 100 ℃, at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the cumulative mass of the industrial oxygen input into the kiln is 510.07 kg, the exhaust pipe is opened to release to the normal pressure, then the kiln is started to naturally cool to the room temperature, and the calcined tungsten waste material is obtained.

[0065] The pressure control method in the kiln in the step four is as follows: when the pressure sensor in the kiln detects that the pressure in the kiln is lower than 115 KPa, the pressure sensor and the electromagnetic valve on the oxygen input pipe are connected to the PLC chip, the feedback electric signal of the pressure sensor controls the electromagnetic valve on the oxygen input pipe to open, until the pressure sensor in the kiln detects that the pressure in the kiln is greater than or equal to 120 KPa, the feedback electric signal of the pressure sensor controls the electromagnetic valve on the oxygen input pipe to close.

[0066] The difference between the example 3 and the example 1 is that: in the step four, after the calcination and oxidation reaction for 6 hours, the kiln stops the electric heating, the oxygen is continuously input, the pressure in the kiln is maintained between 100-102 KPa under the oxygen atmosphere, after 196 minutes, it is observed that the oxygen input amount is 45 sccm (≤50 sccm), at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the cumulative mass of the industrial oxygen input into the kiln is 506.86 kg, the oxygen is continuously input for 0.5 hours, the pressure in the kiln is maintained between 100-102 KPa under the oxygen atmosphere, after 0.5 hours, the exhaust pipe is opened, the nitrogen at 4 ℃ is input to replace the oxygen, the nitrogen flow rate is 0.4 m 3 / min, after 15 minutes, the oxygen in the kiln is completely replaced, the nitrogen is continuously input at the flow rate of 0.4 m 3 / min flow rate of nitrogen into the kiln, so that the temperature in the kiln is rapidly reduced to 100°C, and then the kiln is opened and cooled to room temperature by natural cooling, to obtain the calcined tungsten waste material.

[0067] Example 4 differs from Example 1 in that: in step two, the kiln is turned on and electrically heated, so that the temperature in the kiln is rapidly increased to 900°C at a rate of 8°C / min; in step three, the exhaust pipe is opened, industrial oxygen is introduced into the kiln, and the air in the kiln is exhausted, the exhaust pipe is closed, and industrial oxygen is continuously introduced into the kiln, so that the pressure in the kiln is maintained at 100-102 KPa, the electric heating power of the kiln is controlled at 2.2 kW, and the calcination oxidation reaction is performed for 5 h, the temperature in the kiln is gradually increased to 1024.9°C after 5 h, due to the release of a large amount of heat from the reaction of tungsten and oxygen, the amount of industrial oxygen introduced is 424.09 kg;

[0068] In step four, after the calcination oxidation reaction is performed for 5 h, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the pressure in the kiln is maintained at 100-102 KPa in an oxygen atmosphere, after 128 min, it is observed that the amount of oxygen introduced is 38 sccm (≤50 sccm), at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the mass of industrial oxygen introduced into the kiln is 507.11 kg, the oxygen is introduced into the kiln until the pressure in the kiln is 120 KPa, and then the oxygen introduction is stopped, the temperature in the kiln is reduced to 100°C, the kiln is opened, and the kiln is cooled to room temperature by air cooling, to obtain the calcined tungsten waste material.

[0069] Example 5 differs from Example 4 in that: in step four, after the calcination oxidation reaction is performed for 5.0 h, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the pressure in the kiln is maintained at 100-102 KPa in an oxygen atmosphere, after 128 min, it is observed that the amount of oxygen introduced is 36 sccm (≤50 sccm), at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the mass of industrial oxygen introduced into the kiln is 507.34 kg, the oxygen is introduced into the kiln by pressurization, the pressure in the kiln is maintained at 115-120 KPa, the temperature in the kiln is reduced to 100°C in an oxygen atmosphere, at this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the mass of industrial oxygen introduced into the kiln is 510.36 kg, the exhaust pipe is opened to release to normal pressure, then the kiln is opened and cooled to room temperature by natural cooling, to obtain the calcined tungsten waste material.

[0070] Example 6 differs from Example 1 in that: step two, the furnace is turned on and heated to 1000°C at a rate of 8°C / min; step three, the exhaust pipe is opened and industrial oxygen is introduced into the furnace to exhaust the air in the furnace, the exhaust pipe is closed and industrial oxygen is continuously introduced into the furnace to maintain the pressure in the furnace between 100-102 KPa, the power of the electric heating of the furnace is controlled to be 3.0 kW in an oxygen atmosphere, the calcination oxidation reaction is 4.0 h, the temperature in the furnace increases from the initial 1080°C to 1189.5°C after 4 h due to the release of a large amount of heat during the reaction of tungsten and oxygen, the amount of industrial oxygen introduced is 393.71 kg;

[0071] Step four, after 4 h of calcination oxidation reaction, the furnace stops heating, oxygen is continuously introduced, the pressure in the furnace is maintained between 100-102 KPa in an oxygen atmosphere, after 93 min, it is observed that the oxygen flow is 30 sccm (≤50 sccm), at this time, the gas flow meter on the industrial oxygen inlet pipe is observed, and it is calculated that the mass of industrial oxygen introduced into the furnace is 507.84 kg, the oxygen is introduced into the furnace until the pressure in the furnace reaches 120 KPa, then the oxygen introduction is stopped, and the furnace is opened when the temperature in the furnace decreases to 100°C, and the furnace is cooled to room temperature in an air cooling manner, to obtain calcined tungsten waste.

[0072] Comparative Example 1 differs from Example 1 in that: step two, the furnace is turned on and heated to 600°C at a rate of 8°C / min; step three, the exhaust pipe is opened and industrial oxygen is introduced into the furnace to exhaust the air in the furnace, the exhaust pipe is closed and industrial oxygen is continuously introduced into the furnace to maintain the pressure in the furnace between 100-102 KPa, the power of the electric heating of the furnace is controlled to be 1.2 kW in an oxygen atmosphere, the calcination oxidation reaction is 10 h, the temperature in the furnace increases from the initial 600°C to 692.5°C after 5 h due to the release of a large amount of heat during the reaction of tungsten and oxygen, the amount of industrial oxygen introduced is 340.74 kg, the temperature gradually increases to 748.1°C after 10 h, and the amount of industrial oxygen introduced is 392.17 kg;

[0073] Step four, after 10 h of calcination oxidation reaction, the furnace stops heating, oxygen is continuously introduced, the pressure in the furnace is maintained between 100-102 KPa in an oxygen atmosphere, after 312 min, it is observed that the oxygen flow is ≤50 sccm, at this time, the gas flow meter on the industrial oxygen inlet pipe is observed, and it is calculated that the mass of industrial oxygen introduced into the furnace is 494.21 kg, the temperature in the furnace decreases to 100°C, the furnace is opened, and the furnace is cooled to room temperature in an air cooling manner, to obtain calcined tungsten waste.

[0074] The difference between Comparative Example 2 and Example 6 is that in Step 2, the furnace is opened and electric heating is turned on to rapidly increase the temperature in the furnace to 1300℃ at a rate of 8℃ / min; in Step 3, the exhaust pipe is opened, industrial oxygen is introduced into the furnace to exhaust the air in the furnace, the exhaust pipe is closed, and industrial oxygen is continuously introduced into the furnace to maintain the pressure in the furnace between 100-102Kpa, the electric heating power of the furnace is controlled to be 1.2kW in the oxygen atmosphere, the calcination oxidation reaction is 4h, the temperature in the furnace is gradually increased to 1408.5℃ after 4h due to the release of a large amount of heat during the reaction of tungsten and oxygen, and the amount of industrial oxygen introduced is 400.35kg;

[0075] In Step 4, after 4h of calcination oxidation reaction, the furnace stops electric heating, oxygen is continuously introduced, and the pressure in the furnace is maintained between 100-102Kpa in the oxygen atmosphere. After 78min, it is observed that the oxygen flow rate is 42sccm (≤50sccm), at which time the gas flow meter on the industrial oxygen inlet pipe is observed, and it is calculated that the total amount of industrial oxygen introduced into the furnace is 507.94kg. The oxygen is introduced into the furnace until the pressure in the furnace reaches 120Kpa, and then the oxygen introduction is stopped. The temperature in the furnace is reduced to 100℃, the furnace is opened, and the temperature is reduced to room temperature in an air cooling manner to obtain the calcined tungsten waste material.

[0076] The recovery rate is calculated as follows: The high-purity tungsten oxide powder obtained in the tungsten waste recovery process in Examples 1-6 and Comparative Examples 1-2 is weighed as M 测 , M 标 is 0.9178*2*10 6 *231.84 / 183.84=2314868.9g, the recovery rate P(%) is M 测 *100 / M 标 . The particle size distribution and median diameter D 50 of the high-purity tungsten oxide powder are measured by NKT2010-L dry method particle size analyzer. The time consumed in the tungsten waste recovery process is taken as the time consumed / h when the temperature is reduced to 100℃ in Step 4, which is used to compare the efficiency differences between the various groups in the table.

[0077] Table 1: Comparison of parameters in the tungsten waste recovery process in Examples 1-6 and Comparative Examples 1-2

[0078] Particle size distribution / pm Median diameter D 50 / μm Recovery time Recovery rate / % Example 1 32～94 66 15h 32min 32s 99.04 Example 2 30～87 59 15h 25min 30s 99.11 Example 3 25～74 50 11h 6min 55s 98.78 Example 4 27～81 52 15h 18min 48s 99.46 Example 5 23～76 49 15h 11min 29s 99.52 Example 6 19～64 43 15h 35min 56s 99.69 Comparative Example 1 36～102 72 18h 19min 49s 97.21 Comparative Example 2 18～64 41 15h 20min 48s 99.71

[0079] As can be seen from Examples 1-5 and Comparative Example 1 and Table 1, in Step 2, the temperature in the furnace is rapidly increased to above 700℃ and the calcination oxidation reaction is carried out for 2-6h at above 700℃, which can more fully calcine and oxidize the tungsten metal in the tungsten waste to ensure that the recovery rate of the tungsten metal is above 99%.

[0080] From the combination of Example 1 and Example 2 and in combination with Table 1, it can be seen that the oxygen pressurization treatment in step four can further calcine and oxidize the residual tungsten metal, thereby further improving the recovery rate of tungsten metal.

[0081] From the combination of Example 1 and Example 3 and in combination with Table 1, it can be seen that the low-temperature nitrogen gas used in step four to accelerate cooling can refine the particle size of the milled powder, and more target product-tungsten oxide can be screened out by gravity, while the tungsten waste recovery process time is also shortened, but the recovery rate of tungsten metal is slightly decreased.

[0082] From the combination of Example 1 and Example 4 and in combination with Table 1, it can be seen that the recovery process of Example 4 takes a little shorter time, but the overall time is not much shortened. Although the calcination time of Example 4 in step three is reduced by 1 h, Example 4 is heated to 900°C, while Example 1 is heated to 750°C. Example 4 has 18.75 min more in heating time, and in the power-off cooling stage, Example 4 also needs to be power-off cooled by 150°C.

[0083] From the combination of Example 1 and Example 6 and in combination with Table 1, it can be seen that the recovery process of Example 5 takes a little longer time, although the calcination time of Example 6 in step three is reduced by 2 h, but Example 6 is heated to 1000°C, while Example 1 is heated to 750°C. Example 6 has 41.25 min more in heating time, and in the power-off cooling stage, Example 6 also needs to be power-off cooled by 250°C.

[0084] From the combination of Example 1 and Example 4, Example 6 and in combination with Table 1, it can be seen that the recovery rate of tungsten metal of Example 6 is better than that of Example 4 and Example 1, and it is appropriate to use the recovery process of Example 6.

[0085] From the combination of Example 6 and Comparative Example 2 and in combination with Table 1, it can be seen that when the calcination temperature exceeds 1250°C, the recovery rate of the final tungsten metal is less affected, but the overall tungsten waste recovery process energy consumption increases, thereby leading to an increase in the cost of tungsten waste recovery. Therefore, it is appropriate to control the calcination temperature in the tungsten waste recovery process to be between 700-1250°C, and preferably, the calcination temperature in the tungsten waste recovery process is controlled to be between 900-1100°C.

[0086] From the perspective of improving the recovery rate of tungsten metal, the oxygen flow rate in step four is ≤50sccm, the pressurization method is to introduce oxygen into the kiln, the pressure in the kiln is maintained at 115-120KPa, and the temperature in the kiln is reduced to 100°C under the oxygen atmosphere. The kiln is naturally cooled to room temperature to obtain calcined tungsten waste, which has a higher recovery rate of tungsten metal.

[0087] From the perspective of optimizing the tungsten waste recovery time, the oxygen flow rate in step four is ≤50sccm, the emptying pipe is opened after 30 min, low-temperature nitrogen gas is introduced to replace oxygen, the nitrogen gas flow rate is 0.2-0.6m3 / min, so that the temperature in the kiln is rapidly reduced to 100 DEG C after opening the furnace and the calcined tungsten waste is naturally cooled to room temperature, the overall process time can be reduced by about 4h, but the recovery rate is less than 99%, the tungsten particles are more, and it is only suitable as a raw material instead of tungsten concentrate, resulting in a decrease in the overall application value. The high-purity tungsten oxide powder in examples 5-6, 5 with a recovery rate of less than 99.5% can be applied to the field of optoelectronic information, and the production of electrochromic windows and other photoelectric products.

[0088] In summary, the tungsten waste recovery process provided by the present application has the advantages of small investment, low consumption cost, low manual operation difficulty, easy automation of equipment, short process flow, high metal recovery rate, and is suitable for large-scale recovery of tungsten waste.

Claims

1. A method for preparing oxides from tungsten-containing waste using a kiln, characterized in that: The steps are as follows: Step 1: Place the clumps and strands of tungsten-containing waste into the silicon carbide rack in the kiln and close the kiln. Step 2: Turn on the electric heating to rapidly raise the temperature inside the kiln to 750-1250℃; Step 3: Introduce oxygen into the kiln to purge the air inside. Continue to introduce oxygen and maintain the pressure inside the kiln at 100-102 kPa. Control the electric heating power of the kiln under the oxygen atmosphere to maintain the temperature inside the kiln at 750-1250℃. Calcinate and oxidize at 750-1250℃ for 2-6 hours. Step 4: After the calcination and oxidation reaction is completed, stop the electric heating and continue to introduce oxygen. Maintain the pressure inside the kiln at 100-102 kPa. Under the oxygen atmosphere, after the temperature inside the kiln drops to 100-200℃, open the furnace and let it cool naturally to room temperature to obtain calcined tungsten waste. Step 5: The calcined tungsten waste from Step 4 is ball-milled and gravity-screened to obtain high-purity tungsten oxide powder; The purity of the high-purity tungsten oxide is ≥99.5%.

2. The method for preparing tungsten-containing waste into oxides using a kiln according to claim 1, characterized in that: The kiln has a volume of 4-8.0 m³. 3 The load mass of tungsten waste on the silicon carbide placement rack in the kiln is 1.5-4.0t; the heating rate of the kiln is 0.1-8.33℃ / min, and the output power is 0-450kW.

3. The method for preparing tungsten-containing waste into oxides using a kiln according to claim 1, characterized in that: The elemental composition of the tungsten waste in step one includes tungsten and M, wherein M is one or more combinations of C, N, S, Si, Ni, Fe, Cu, Co, Ag, Ti, Ta, Ru, Rh, Zr, Mo, Al, Hf, Ir, Te, and Ga.

4. The method for preparing tungsten-containing waste into oxides using a kiln according to claim 3, characterized in that: Before step one, elemental analysis is performed on the tungsten waste to be recycled. This analysis reveals the content of tungsten and methyl sulfide (M) in the waste. The calcination oxidation reaction equation for tungsten is 2W + 3O₂ = 2WO₃; the calcination oxidation reaction equation for methyl sulfide is XM + 0.5Y*O₂ = M. X O Y The amount of oxygen required for the complete calcination and oxidation of tungsten and M in tungsten waste was calculated using the calcination and oxidation reaction equation of tungsten and M. 标 In steps three and four, the total mass M of oxygen input into the kiln 实 The amount of oxygen used by the complete calcination and oxidation of tungsten and M in tungsten waste 标 The mass ratio is (99-104):

100.

5. A method for preparing tungsten-containing waste into oxides using a kiln according to claim 4, characterized in that: In step four, after the calcination and oxidation reaction is completed, the electric heating of the kiln is stopped, and oxygen is continuously introduced. The pressure inside the kiln is maintained at 100-102 kPa. Under the oxygen atmosphere, the temperature inside the kiln drops to 100°C and then the kiln is opened to allow it to cool naturally to room temperature, thus obtaining calcined tungsten waste.

6. A method for preparing tungsten-containing waste into oxides using a kiln according to claim 4, characterized in that: In step two, the kiln is electrically heated at a rate of 7.5-8.2℃ / min to rapidly raise the temperature inside the kiln to 950-1050℃. In step three, oxygen is introduced into the kiln to purge the air inside. Oxygen is continuously introduced to maintain the pressure inside the kiln at 100-102 kPa. Under the oxygen atmosphere, the electric heating power of the kiln is controlled at 2.0-3.5 kW to maintain the temperature inside the kiln between 950 and 1200℃. The calcination oxidation reaction is carried out at 950-1200℃ for 4.0 hours.

7. A method for preparing tungsten-containing waste into oxides using a kiln according to claim 4, characterized in that: In step three, oxygen is introduced into the kiln to purge the air inside. Oxygen is continuously introduced to maintain the kiln pressure at 100-102 kPa. Under this oxygen atmosphere, the electric heating power of the kiln is controlled at 1.0-3.5 kW to maintain the kiln temperature between 750 and 1250°C for the calcination and oxidation reaction until the cumulative oxygen input V to the kiln in step three is reached. 时 The amount of oxygen used is equal to the amount of tungsten and M completely calcined and oxidized in tungsten waste. 标 0.70-0.90 times.

8. A method for preparing tungsten-containing waste into oxides using a kiln according to claim 7, characterized in that: In step four, after the calcination and oxidation reaction is completed, the electric heating of the kiln is stopped, and oxygen is continuously introduced. The pressure inside the kiln is maintained at 100-102 kPa. When the oxygen supply is ≤50 sccm, oxygen is introduced into the kiln by pressurization, and the pressure inside the kiln is maintained at 115-120 kPa. Under the oxygen atmosphere, the temperature inside the kiln drops to 100°C, and then the kiln is opened and allowed to cool naturally to room temperature to obtain calcined tungsten waste.

9. A method for preparing tungsten-containing waste into oxides using a kiln according to claim 7, characterized in that: In step four, after the calcination and oxidation reaction is completed, the electric heating of the kiln is stopped, and oxygen is continuously introduced. The pressure inside the kiln is maintained at 100-102 kPa. When the oxygen introduction rate is ≤50 sccm, the vent pipe is opened after 0.5-1 hour to introduce low-temperature nitrogen to replace the oxygen. The nitrogen flow rate is 0.2-0.6 m / s. 3 The furnace temperature is reduced to 100℃ by a speed of 0.5 min, after which the furnace is opened and allowed to cool naturally to room temperature, thus obtaining calcined tungsten waste.

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