Method for preparing oxide from tungsten-containing waste by adopting kiln

Abstract

The invention relates to the technical field of tungsten waste recovery, in particular to a method for preparing tungsten-containing waste into oxide by adopting a kiln. The method for preparing the oxide from the tungsten-containing waste by adopting the kiln comprises the following steps: putting the tungsten waste into the kiln, rapidly heating to 750-1250 DEG C, introducing oxygen into the kiln, exhausting air in the kiln, continuously introducing oxygen, carrying out calcination oxidation reaction on the tungsten waste at 750-1250 DEG C in an oxygen atmosphere for 2-4 hours, stopping electric heating in the kiln after the calcination oxidation reaction is finished, and carrying out heat preservation for 2-4 hours; and continuously introducing oxygen, cooling to 100 DEG C in the oxygen atmosphere, opening the furnace, cooling to room temperature, and carrying out ball milling and gravity screening on the calcined tungsten waste to obtain the high-purity tungsten oxide powder. The tungsten waste material recovery process provided by the invention is small in investment, low in consumption cost, low in manual operation difficulty, easy to realize automation of equipment, short in process flow, high in metal recovery rate and suitable for large-scale recovery of tungsten waste materials.

Description

Technical Field

[0001] The present application relates to the technical field of tungsten waste recovery, and in particular to a method for preparing tungsten-containing waste into oxides using a kiln. Background Art

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

[0003] In the process of tungsten material processing, tungsten-containing waste is inevitably generated. These tungsten-containing wastes mainly include tungsten wire after nickel removal, waste tungsten wire that does not meet the standards during the production process, and tungsten-nickel diamond wires produced in the photovoltaic industry. Tungsten-containing waste has a high tungsten content and high recycling value. Tungsten waste recycling is of great significance and value. By recycling waste tungsten products, it can not only reduce the mining of primary tungsten resources and protect limited natural resources, but also help reduce the pollution of waste to the environment and reduce the risk of ecological damage.

[0004] At present, the existing industrial technology for recycling the tungsten-containing waste in the form of wire produced in the tungsten material processing link 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 tungsten-containing waste, the operation of the above process is complicated and difficult, and industrial waste is generated during the recycling process, which is less environmentally friendly and leads to high recycling costs for tungsten-containing waste. To this end, the inventor provides a method for preparing tungsten-containing waste into oxide using a kiln. Summary of the invention

[0005] In order to solve the problems in the prior art of complex operation, high difficulty, generation of industrial waste during the recycling process, poor environmental performance, and high cost of recycling tungsten-containing waste, the present invention provides a method for preparing tungsten-containing waste into oxides using a kiln, which has small investment, low consumption cost, low difficulty in manual operation, short process flow, high recovery rate, good environmental performance, and is suitable for large-scale recycling of tungsten waste.

[0006] The present invention provides a method for preparing tungsten-containing waste into oxides using a kiln, which is achieved by the following technical solutions:

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

[0008] Step 1: Place the tungsten waste on the silicon carbide placement rack in the kiln and close the kiln;

[0009] Step 2: Turn on the electric heating to quickly raise the temperature in the kiln to 750-1250°C;

[0010] Step 3, introducing oxygen into the kiln, exhausting the air in the kiln, continuously introducing oxygen, controlling the electric heating power of the kiln in the oxygen atmosphere, maintaining the temperature in the kiln at 750-1250° C., and calcining the oxidation reaction at 750-1250° C. for 2-6 hours;

[0011] Step 4: After the calcination oxidation reaction is completed, the electric heating is stopped and oxygen is continuously introduced. In the oxygen atmosphere, the temperature in the kiln is reduced to 100°C-200°C and then the kiln is opened to cool naturally to room temperature to obtain calcined tungsten waste;

[0012] Step 5: ball milling and gravity screening the calcined tungsten waste in step 4 to obtain high-purity tungsten oxide powder.

[0013] The present invention is particularly suitable for tungsten-containing waste materials in the form of wire-shaped tungsten wires after nickel removal, waste tungsten wires generated in the production process, and tungsten-nickel diamond wires generated in the photovoltaic industry. These tungsten-containing waste materials can be prepared into tungsten oxide using a kiln to prepare tungsten-containing waste into oxides, thereby realizing large-scale recovery of tungsten waste materials.

[0014] According to the method, the tungsten-containing waste is stacked on a high-temperature resistant waste placement rack. The high-temperature resistant silicon carbide waste placement rack can play a good supporting role for the tungsten-containing waste in the form of agglomerates or strands, so that the tungsten-containing waste in the form of agglomerates or strands can still maintain the state of being agglomerated or stranded when fed after calcination, and thus a large amount of dust will not be generated during the calcination process and when it is taken out, thereby reducing the adverse effects of the tungsten oxide preparation process.

[0015] In the process of introducing oxygen into the kiln for calcination of tungsten-containing waste in the method, 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 under the condition of high-temperature calcination, the oxygen can be well combined with the tungsten-containing waste, and the combination of tungsten itself and oxygen can also release a large amount of heat, which can fully promote the calcination; the preset temperature range and the predetermined time range are used as the calcination conditions, which ensures that the tungsten-containing waste can achieve the expected calcination effect, and effectively improves the recovery efficiency of tungsten waste.

[0016] The calcined tungsten-containing waste can be ball-milled to obtain powdered oxides, and then the non-oxide impurities with relatively low density are screened by gravity. The powder screened by gravity is high-purity tungsten oxide powder (a very small amount of tungsten particles). Subsequently, the high-purity tungsten oxide powder is calcined and reduced under hydrogen or carbon monoxide to obtain high-purity tungsten particles.

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

[0018] Preferably, the volume of the kiln is 4-8.0m 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 the step 1 includes tungsten and M, and 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 1, the tungsten waste to be recycled is subjected to element determination. By determining the elements of the tungsten waste, the contents of tungsten and M in the tungsten waste to be recycled can be known. The calcination oxidation reaction equation of tungsten is 2W+3O 2 =2WO 3 ; The calcination oxidation reaction equation of M is XM+0.5Y*0 2 =M X O Y The oxygen consumption M obtained by complete calcination and oxidation of tungsten and M in tungsten waste is calculated by the calcination and oxidation reaction equation of tungsten and M. 标 The total mass M of oxygen input into the kiln in step 3 and step 4 is 实 The amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 The mass ratio is (99-104):100.

[0022] By adopting the above technical solution, the recovery rate of tungsten metal can be effectively improved, and it is also convenient to control the reaction process, thereby optimizing the calcination procedure, reducing the overall energy consumption, and reducing the recovery cost of tungsten waste.

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

[0024] Preferably, in step 4, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the pressure inside the kiln is maintained at 100-102 KPa. In the oxygen atmosphere, the temperature inside the kiln drops to 100°C and then the kiln is opened to cool naturally to room temperature to obtain calcined tungsten waste.

[0025] Preferably, in the step 2, the kiln is electrically heated at a heating rate of 7.5-8.2°C / min, so that the temperature inside the kiln is rapidly raised to 750-1250°C.

[0026] Further preferably, in the step 2, the kiln is electrically heated at a heating rate of 7.5-8.2°C / min, so that the temperature inside the kiln is rapidly raised to 950-1050°C; in the step 3, oxygen is introduced into the kiln to exhaust the air in the kiln, and oxygen is continuously introduced to maintain the pressure inside the kiln at 100-102Kpa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 2.0-3.5kW, and the temperature inside the kiln is maintained between 950 and 1250°C. The calcination oxidation reaction is carried out at 950-1250°C for 4.0h.

[0027] By adopting the above technical solution, the recovery rate of tungsten metal can be effectively improved while reducing the power consumption of the kiln in the process of oxidative calcination to recover tungsten waste, thereby optimizing the recovery cost of tungsten waste.

[0028] Preferably, in step 3, oxygen is introduced into the kiln to exhaust the air in the kiln, and oxygen is continuously introduced to maintain the pressure in the kiln at 100-102 KPa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 1.0-3.5 kW, and the temperature in the kiln is maintained between 750 and 1250° C. to calcine the oxidation reaction until the cumulative oxygen V input into the kiln in step 3 reaches 时 Equal to the amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 0.70-0.90 times of.

[0029] Preferably, in step 3, oxygen is introduced into the kiln to exhaust the air in the kiln, and oxygen is continuously introduced to maintain the pressure in the kiln at 100-102 KPa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 1.0-3.5 kW, and the temperature in the kiln is maintained between 750 and 1250° C. to calcine the oxidation reaction until the cumulative oxygen V input into the kiln in step 3 reaches 时 Equal to the amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 0.75-0.80 times of.

[0030] By controlling the cumulative input of oxygen V into the kiln 时 , optimize the calcination procedure, and shorten the time for oxidative calcination to recover tungsten waste while ensuring a high recovery rate of tungsten metal. This can effectively reduce the power consumption of the kiln during the oxidative calcination process to recover tungsten waste, thereby optimizing the recovery cost of tungsten waste.

[0031] Preferably, in step 4, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the internal pressure of the kiln is maintained at 100-102 KPa. When the oxygen introduction amount is ≤50 sccm, the exhaust pipe is opened after 0.5-1h, and low-temperature nitrogen is introduced to replace the oxygen. The nitrogen flow rate is 0.2-0.6m 3 / min, so that the temperature in the kiln quickly drops to 100℃, then the furnace is opened and naturally cooled to room temperature to obtain calcined tungsten waste.

[0032] By using low-temperature nitrogen to quickly cool down the powder, the particle size of the powder after ball milling can be refined, and the tungsten particles and tungsten oxide can be screened out by gravity. The screened materials are non-tungsten metals and their oxides, which can increase the recovery rate of tungsten metal.

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

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

[0035] 2. The equipment used in the present invention is a kiln with a capacity of six cubic meters, which can process two tons of tungsten waste and is suitable for large-scale recycling of tungsten waste, thereby reducing the cost of recycling tungsten waste.

[0036] 3. The present invention adopts a kiln to prepare tungsten-containing waste into oxide, which is a high-purity* (≥99.5%) tungsten oxide obtained by calcining tungsten waste and then ball milling and gravity screening. Its application value is relatively high and can be applied to the field of optoelectronic information to produce optoelectronic products such as electrochromic windows. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 1 is a graph showing the relationship between temperature and time during the calcination of tungsten waste in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to further understand the creativity and technical advancement of the present invention, the preferred embodiments of the present invention are discussed in detail below in conjunction with examples and comparative examples.

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

[0040] Step 1: Place the tungsten waste on the silicon carbide placement rack in the kiln and close the kiln;

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

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

[0043] The element composition of the tungsten waste suitable for this method includes tungsten and M, where 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, and Ga;

[0044] Preferably, before step 1, the tungsten waste to be recycled is subjected to element determination, and the tungsten and M contents in the tungsten waste to be recycled can be known through element determination. The calcination oxidation reaction equation of tungsten is 2W+3O 2 =2WO 3 ; The calcination oxidation reaction equation of M is XM+0.5Y*0 2 =M X O Y The oxygen consumption M obtained by complete calcination and oxidation of tungsten and M in tungsten waste is calculated by the calcination and oxidation reaction equation of tungsten and M. 标 ;

[0045] Step 2: The kiln is electrically heated at a rate of 7.5-8.2°C / min, so that the temperature in the kiln is rapidly raised to 750-1250°C;

[0046] Step 3, introducing oxygen into the kiln, exhausting the air in the kiln, continuously introducing oxygen, controlling the electric heating power of the kiln in the oxygen atmosphere, maintaining the temperature in the kiln between 750 and 1250° C., and calcining the oxidation reaction at 750 to 1250° C. for 2.0 to 6.0 hours;

[0047] Preferably, in step three, oxygen is introduced into the kiln to exhaust the air in the kiln, oxygen is continuously introduced to maintain the pressure in the kiln at 100-102 KPa, and in the oxygen atmosphere, the electric heating power of the kiln is controlled to be 2.0-3.5 kW, the temperature in the kiln is maintained at 950-1250° C., and the calcination oxidation reaction is carried out at 950-1250° C. for 4 hours;

[0048] Alternatively, preferably, in step 3, oxygen is introduced into the kiln to exhaust the air in the kiln, and oxygen is continuously introduced to maintain the pressure in the kiln at 100-102 KPa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 1.0-3.5 kW, and the temperature in the kiln is maintained between 750 and 1250° C. to calcine the oxidation reaction until the cumulative oxygen V input into the kiln in step 3 reaches 时 Equal to the amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 0.65-0.90 times;

[0049] Preferably, the temperature in the kiln is maintained between 750°C and 1250°C for calcination oxidation reaction until the cumulative oxygen V input into the kiln in step 3 is 时 Equal to the amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 0.75-0.80 times;

[0050] Step 4: After the calcination oxidation reaction is completed, the kiln stops electric heating and continues to introduce oxygen. In the oxygen atmosphere, the pressure in the kiln is maintained at 100-102Kpa. After the temperature in the kiln drops to 100°C, the kiln is opened and cooled by air to room temperature to obtain calcined tungsten waste.

[0051] Or preferably, in step 4, after the calcination oxidation reaction is completed, the kiln stops electric heating, oxygen is continuously introduced, and the pressure in the kiln is maintained at 100-102 KPa. When the oxygen introduction amount is ≤50 sccm, oxygen is introduced into the kiln in a pressurized manner, and the pressure in the kiln is maintained at 115-120 KPa. In the oxygen atmosphere, the temperature in the kiln drops to 100° C. and then the kiln is opened to naturally cool to room temperature, thereby obtaining calcined tungsten waste;

[0052] Or preferably, in step 4, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the internal pressure of the kiln is maintained at 100-102KPa. When the oxygen introduction amount is ≤50sccm, the exhaust pipe is opened after 0.5-1h, and low-temperature nitrogen is introduced to replace the oxygen. The nitrogen flow rate is 0.2-0.6m 3 / min, so that the temperature in the kiln quickly drops to 100°C, then the furnace is opened and naturally cooled to room temperature to obtain calcined tungsten waste;

[0053] The total mass of oxygen M input into the kiln in steps 3 and 4 实 The amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 The mass ratio is (99-104):100; it should be noted that the total mass of oxygen M 实 It is related to calcination temperature, holding time, pressure in the kiln, and cooling method;

[0054] Step 5: ball milling and gravity screening the calcined tungsten waste in step 4 to obtain high-purity tungsten oxide powder.

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

[0056] The tungsten waste is the tungsten-nickel diamond wire discarded in the photovoltaic industry. Before the tungsten waste is loaded on the silicon carbide placement rack in the kiln, the tungsten waste is subjected to element determination. The tungsten (W) content of the tungsten-nickel diamond wire to be recycled is 91.78%, the nickel (Ni) content is 7.15%, and the oxygen (O) content is 0.85%. The tungsten and nickel content in the tungsten waste to be recycled can be determined by element determination. The calcination oxidation reaction equation of tungsten is 2W+3O 2 =2WO 3 ; The calcination oxidation reaction equation of M is XM+0.5Y*0 2 =M X O Y The oxygen consumption M obtained by complete calcination and oxidation of tungsten and nickel in tungsten waste is calculated by the calcination and oxidation reaction equation of tungsten and nickel. 标 , the amount of oxygen required for the complete calcination and oxidation of 2 tons of the above-mentioned discarded tungsten-nickel diamond wire in the photovoltaic industry 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=509.75kg.

[0057] The volume of the kiln used in the present invention 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 1: Place the tungsten waste on the silicon carbide placement rack in the kiln and close the kiln;

[0059] Step 2: The kiln is electrically heated to rapidly raise the temperature in the kiln to 750°C at a rate of 8°C / min.

[0060] Step 3: Open the exhaust pipe, introduce industrial oxygen into the kiln, exhaust the air in the kiln, close the exhaust pipe, continue to introduce industrial oxygen into the kiln, maintain the pressure in the kiln between 100-102Kpa, control the electric heating power of the kiln to 1.5kW in the oxygen atmosphere, and perform the calcination oxidation reaction for 6h. The temperature in the kiln gradually rises from the initial 750℃ to 879.6℃ after 6h as a large amount of heat is released as tungsten and oxygen react. The amount of industrial oxygen introduced is 400.68kg;

[0061] Step 4: After the calcination oxidation reaction is completed for 6 hours, the kiln stops electric heating and continues to introduce oxygen. The pressure in the kiln is maintained between 100-102Kpa in an oxygen atmosphere. After 196 minutes, the oxygen introduction amount is observed to be 42sccm (≤50sccm). At this time, the gas flow meter on the industrial oxygen input pipe is observed. It is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 506.94kg. Oxygen is supplied into the kiln under pressure until the pressure in the kiln reaches 120Kpa, then the oxygen input is stopped. After the temperature in the kiln drops to 100°C, the kiln is opened and cooled to room temperature by air to obtain calcined tungsten waste.

[0062] Step 5: Place the calcined tungsten waste in step 4 in an industrial ball mill and perform ball milling with corundum grinding balls at 240 rpm for 0.5 h to obtain a calcined powder (D 50 52 microns), the ball milled particles are transferred to a specific gravity screening machine for gravity screening, and the particles with a density of ≥7g / cm 3 High-purity tungsten oxide powder can be obtained by mixing the powder.

[0063] The method for controlling the internal pressure of the kiln in step 2 is as follows: when the internal pressure sensor detects that the internal pressure of the furnace is lower than 100Kpa, the internal pressure sensor and the solenoid valve on the oxygen input pipe are connected to the PLC chip, and the internal pressure sensor feedbacks an electrical signal to control the solenoid valve on the oxygen input pipe to open, until the internal pressure sensor detects that the internal pressure of the furnace is ≥120Kpa, and the internal pressure sensor feedbacks an electrical signal to control the solenoid valve on the oxygen input pipe to close.

[0064] The difference between Example 2 and Example 1 is that: in step 4, after the calcination oxidation reaction is completed for 6 hours, the electric heating of the kiln is stopped, and oxygen is continuously introduced to maintain the internal pressure of the kiln between 100-102KPa in the oxygen atmosphere. After 196 minutes, the oxygen introduction amount is observed to be 43sccm (≤50sccm). At this time, the gas flowmeter on the industrial oxygen inlet pipe is observed, and it is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 506.97kg. Oxygen is introduced into the kiln in a pressurized manner, and the internal pressure of the kiln is maintained at 115-120KPa. In the oxygen atmosphere, the temperature in the kiln drops to 100°C. At this time, the gas flowmeter on the industrial oxygen inlet pipe is observed, and it is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 510.07kg. The exhaust pipe is opened to discharge to normal pressure, and then the furnace is opened to cool naturally to room temperature to obtain calcined tungsten waste.

[0065] The method for controlling the internal pressure of the kiln in step 4 is as follows: when the internal pressure sensor detects that the internal pressure of the furnace is lower than 115Kpa, the internal pressure sensor and the solenoid valve on the oxygen input pipe are connected to the PLC chip, and the internal pressure sensor feedbacks an electrical signal to control the solenoid valve on the oxygen input pipe to open, until the internal pressure sensor detects that the internal pressure of the furnace is ≥120Kpa, and the internal pressure sensor feedbacks an electrical signal to control the solenoid valve on the oxygen input pipe to close.

[0066] The difference between Example 3 and Example 1 is that: Step 4, after the calcination oxidation reaction is completed for 6 hours, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the pressure in the kiln is maintained between 100-102KPa in an oxygen atmosphere. After 196 minutes, the oxygen introduction amount is observed to be 45sccm (≤50sccm). At this time, the gas flow meter on the industrial oxygen inlet pipe is observed, and it is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 506.86kg. Oxygen is continuously introduced for 0.5h, and the pressure in the kiln is maintained at 100-102KPa in an oxygen atmosphere. After 0.5h, the exhaust pipe is opened, and 4°C nitrogen is introduced to replace the oxygen, and the nitrogen flow rate is 0.4m 3 / min, and completely replace the oxygen in the kiln after 15 minutes, and continue at 0.4m 3 / min flow rate to input nitrogen into the kiln, so that the temperature in the kiln quickly drops to 100 ° C, then the kiln is opened and naturally cooled to room temperature to obtain calcined tungsten waste.

[0067] The difference between Example 4 and Example 1 is that: in step 2, the kiln is turned on for electric heating, and the temperature in the kiln is quickly raised to 900°C at 8°C / min; in step 3, the exhaust pipe is opened, industrial oxygen is introduced into the kiln, the air in the kiln is exhausted, the exhaust pipe is closed, and industrial oxygen is continuously introduced into the kiln to maintain the pressure in the kiln between 100-102Kpa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 2.2kW, the calcination oxidation reaction is 5h, and the temperature in the kiln gradually rises from the initial 900°C to 1024.9°C after 5h as a large amount of heat is released as tungsten and oxygen react. The amount of industrial oxygen introduced is 424.09kg;

[0068] Step 4: After the calcination oxidation reaction is completed for 5 hours, the electric heating of the kiln is stopped, and oxygen is continuously introduced. The pressure in the kiln is maintained between 100-102Kpa in the oxygen atmosphere. After 128 minutes, the oxygen introduction amount is observed to be 38sccm (≤50sccm). At this time, the gas flow meter on the industrial oxygen input pipe is observed. It is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 507.11kg. Oxygen is pressurized into the kiln until the pressure in the kiln reaches 120Kpa, then the oxygen input is stopped. After the temperature in the kiln drops to 100°C, the kiln is opened and cooled to room temperature by air to obtain calcined tungsten waste.

[0069] The difference between Example 5 and Example 4 is that: in step 4, after the calcination oxidation reaction is completed for 5.0 hours, the electric heating of the kiln is stopped, and oxygen is continuously introduced to maintain the internal pressure of the kiln between 100-102KPa in the oxygen atmosphere. After 128 minutes, the oxygen introduction amount is observed to be 36sccm (≤50sccm). At this time, the gas flowmeter on the industrial oxygen input pipe is observed, and it is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 507.34kg. Oxygen is introduced into the kiln in a pressurized manner, and the internal pressure of the kiln is maintained at 115-120KPa. In the oxygen atmosphere, the temperature in the kiln drops to 100°C. At this time, the gas flowmeter on the industrial oxygen input pipe is observed, and it is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 510.36kg. The exhaust pipe is opened to discharge to normal pressure, and then the furnace is opened to cool naturally to room temperature to obtain calcined tungsten waste.

[0070] The difference between Example 6 and Example 1 is that: in step 2, the kiln is turned on for electric heating, and the temperature in the kiln is quickly raised to 1000°C at 8°C / min; in step 3, the exhaust pipe is opened, industrial oxygen is introduced into the kiln, the air in the kiln is exhausted, the exhaust pipe is closed, and industrial oxygen is continuously introduced into the kiln to maintain the pressure in the kiln between 100-102Kpa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 3.0kW, the calcination oxidation reaction is 4.0h, and the temperature in the kiln gradually rises from the initial 1080°C to 1189.5°C after 4h as a large amount of heat is released as tungsten and oxygen react. The amount of industrial oxygen introduced is 393.71kg;

[0071] Step 4: After the calcination oxidation reaction is completed for 4 hours, the electric heating of the kiln is stopped, and oxygen is continuously introduced. The pressure in the kiln is maintained between 100-102Kpa in an oxygen atmosphere. After 93 minutes, the oxygen introduction amount is observed to be 30sccm (≤50sccm). At this time, the gas flow meter on the industrial oxygen input pipe is observed. It is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 507.84kg. Oxygen is pressurized into the kiln until the pressure in the kiln reaches 120Kpa, then the oxygen input is stopped. After the temperature in the kiln drops to 100°C, the kiln is opened and cooled to room temperature by air to obtain calcined tungsten waste.

[0072] The difference between Comparative Example 1 and Example 1 is that: in step 2, the kiln is turned on for electric heating, and the temperature in the kiln is quickly raised to 600°C at 8°C / min; in step 3, the exhaust pipe is opened, industrial oxygen is introduced into the kiln, the air in the kiln is exhausted, the exhaust pipe is closed, and industrial oxygen is continuously introduced into the kiln to maintain the pressure in the kiln between 100-102Kpa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 1.2kW, the calcination oxidation reaction is 10h, the temperature in the kiln gradually rises from the initial 600°C to 692.5°C after 5h as a large amount of heat is released as tungsten and oxygen react, and the amount of industrial oxygen introduced is 340.74kg, and the temperature gradually rises to 748.1°C after 10h, and the amount of industrial oxygen introduced is 392.17kg;

[0073] Step 4: After the calcination oxidation reaction is completed for 10 hours, the electric heating of the kiln is stopped and oxygen is continuously introduced. The pressure in the kiln is maintained between 100-102Kpa in an oxygen atmosphere. After 312 minutes, it is observed that the oxygen introduction amount is ≤50sccm. At this time, the gas flow meter on the industrial oxygen inlet pipe is observed. It is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 494.21kg. After the temperature in the kiln drops to 100°C, the kiln is opened and cooled to room temperature by air to obtain calcined tungsten waste.

[0074] The difference between Comparative Example 2 and Example 6 is that: in step 2, the kiln is turned on for electric heating, and the temperature in the kiln is quickly raised to 1300°C at 8°C / min; in step 3, the exhaust pipe is opened, industrial oxygen is introduced into the kiln, the air in the kiln is exhausted, the exhaust pipe is closed, and industrial oxygen is continuously introduced into the kiln to maintain the pressure in the kiln between 100-102Kpa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 1.2kW, the calcination oxidation reaction is 4h, and the temperature in the kiln gradually rises from the initial 1300°C to 1408.5°C after 4h as a large amount of heat is released as tungsten and oxygen react. The amount of industrial oxygen introduced is 400.35kg;

[0075] Step 4: After the calcination oxidation reaction is completed for 4 hours, the electric heating of the kiln is stopped, and oxygen is continuously introduced. The pressure in the kiln is maintained between 100-102Kpa in an oxygen atmosphere. After 78 minutes, the oxygen introduction amount is observed to be 42sccm (≤50sccm). At this time, the gas flow meter on the industrial oxygen input pipe is observed, and it is calculated that the cumulative mass of industrial oxygen introduced into the kiln is 507.94kg. Oxygen is pressurized into the kiln until the pressure in the kiln reaches 120Kpa, then the oxygen input is stopped. After the temperature in the kiln drops to 100°C, the kiln is opened and cooled to room temperature by air to obtain calcined tungsten waste.

[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 Example 1 is weighed as M 测 , M标 =0.9178*2*10 6 *231.84 / 183.84=2314868.9g, recovery rate P(%)=M 测 *100 / M 标 The particle size distribution and median diameter D of high-purity tungsten oxide powder were measured using NKT2010-L dry particle size analyzer. 50 The time consumption of the tungsten waste recycling process is the time taken to reduce the temperature to 100°C in step 4 as the recycling time / h, which is used to compare the differences in work efficiency between the various groups in the table.

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

[0078] Particle size distribution / μm <![CDATA[Median diameter D 50 / μm]]> Recycling time Recovery rate / % Example 1 32～94 66 15h32min32s 99.04 Example 2 30～87 59 15h25min30s 99.11 Example 3 25～74 50 11h6min55s 98.78 Example 4 27～81 52 15h18min48s 99.46 Example 5 23～76 49 15h11min29s 99.52 Example 6 19～64 43 15h35min56s 99.69 Comparative Example 1 36～102 72 18h19min49s 97.21 Comparative Example 2 18～64 41 15h20min48s 99.71

[0079] Combining Examples 1-5 with Comparative Example 1 and Table 1, it can be seen that the temperature in the kiln in step 2 is quickly raised to above 700°C and the calcination oxidation reaction is carried out at above 700°C for 2-6 hours, so that the tungsten metal in the tungsten oxide waste can be more fully calcined to ensure that the recovery rate of the tungsten metal is above 99%.

[0080] Combining Example 1 with Example 2 and Table 1, it can be seen that the oxygen pressurization treatment in step 4 can further calcine and oxidize the residual tungsten metal, thereby further improving the recovery rate of the tungsten metal.

[0081] Combining Example 1 with Example 3 and Table 1, it can be seen that the use of low-temperature nitrogen to accelerate cooling in step 4 can refine the particle size of the powder after ball milling, and gravity screen out relatively more target product-tungsten oxide, while also shortening the time of the tungsten waste recycling process, but the recovery rate of tungsten metal is slightly reduced.

[0082] Combining Example 1 with Example 4 and Table 1, it can be seen that the recovery process of Example 4 is shortened, but the overall shortening time is not much. Although the calcination time in step 3 of Example 4 is reduced by 1 hour, Example 4 is heated to 900°C, while Example 1 is heated to 750°C. Example 4 has an additional heating time of 18.75 minutes. In the power-off and cooling stage, Example 4 also needs to be powered off and cooled by 150°C more.

[0083] Combining Example 1 with Example 6 and Table 1, it can be seen that the recovery process of Example 5 takes longer. Although the calcination time in step 3 of Example 6 is reduced by 2 hours, Example 6 is heated to 1000°C, while Example 1 is heated to 750°C. Example 6 has an additional heating time of 41.25 minutes. In the power-off and cooling stage, Example 6 also needs to be powered off and cooled by 250°C more.

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

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

[0086] From the perspective of improving the recovery rate of tungsten metal, after the oxygen introduction amount in step 4 is ≤50sccm, oxygen is introduced into the kiln by means of pressurization, and the pressure in the kiln is maintained at 115-120KPa in an oxygen atmosphere. After the temperature in the kiln drops to 100°C, the kiln is opened and naturally cooled to room temperature to calcine the tungsten waste, which has a higher recovery rate of tungsten metal.

[0087] From the perspective of improving and optimizing the recovery time of tungsten waste, the oxygen intake in step 4 is ≤50sccm. After 30 minutes, the exhaust pipe is opened and low-temperature nitrogen is introduced to replace oxygen. The nitrogen flow rate is 0.2-0.6m 3 / min, so that the temperature in the kiln quickly drops to 100°C, then the furnace is opened and naturally cooled to room temperature to obtain calcined tungsten waste. The overall process time can be reduced by about 4 hours, but its recovery rate is lower than 99%, and there are too many doped tungsten particles, which is only suitable as a raw material to replace tungsten concentrate, resulting in a decrease in the overall application value. The high-purity tungsten oxide powder in Examples 5-6 and 5 with a recovery rate lower than 99.5% can be used in the field of optoelectronic information to produce optoelectronic products such as electrochromic windows.

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

Claims

1. A method for preparing tungsten-containing waste into oxides using a kiln, characterized in that: Here are the steps: Step 1: Place the tungsten waste on the silicon carbide placement rack in the kiln and close the kiln; Step 2: Turn on the electric heating to quickly raise the temperature in the kiln to 750-1250°C; Step 3, introducing oxygen into the kiln, exhausting the air in the kiln, continuously introducing oxygen, controlling the electric heating power of the kiln in the oxygen atmosphere, maintaining the temperature in the kiln at 750-1250° C., and calcining the oxidation reaction at 750-1250° C. for 2-6 hours; Step 4: After the calcination oxidation reaction is completed, the electric heating is stopped and oxygen is continuously introduced. In the oxygen atmosphere, the temperature in the kiln is reduced to 100°C-200°C and then the kiln is opened to cool naturally to room temperature to obtain calcined tungsten waste; Step 5: ball milling and gravity screening the calcined tungsten waste in step 4 to obtain high-purity tungsten oxide powder.

2. The method of preparing tungsten-containing waste into oxides using a kiln according to claim 1, characterized in that: The volume of the kiln is 4-8.0m 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 of preparing tungsten-containing waste into oxides using a kiln according to claim 1, characterized in that: The elemental composition of the tungsten waste in the step 1 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 of preparing tungsten-containing waste into oxides using a kiln according to claim 1, characterized in that: Before the step 1, the tungsten waste to be recycled is subjected to element determination. By determining the elements of the tungsten waste, the contents of tungsten and M in the tungsten waste to be recycled can be 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 oxygen consumption M obtained by complete calcination and oxidation of tungsten and M in tungsten waste is calculated by the calcination and oxidation reaction equation of tungsten and M. 标 The total mass M of oxygen input into the kiln in step 3 and step 4 is 实 The amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 The mass ratio is (99-104):

100.

5. The method of preparing oxides from tungsten-containing waste using a kiln according to claim 4, characterized in that: In the step three, oxygen is introduced into the kiln to exhaust the air in the kiln, and oxygen is continuously introduced to maintain the pressure in the kiln at 100-102 KPa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to maintain the temperature in the kiln at 750-1250°C, and the calcination oxidation reaction is carried out at 750-1250°C for 2-6 hours.

6. The method of preparing oxides from tungsten-containing waste using a kiln according to claim 4, characterized in that: In the step 4, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the pressure inside the kiln is maintained at 100-102KPa. After the temperature inside the kiln drops to 100°C in an oxygen atmosphere, the kiln is opened and naturally cooled to room temperature to obtain calcined tungsten waste.

7. The method of preparing oxides from tungsten-containing waste using a kiln according to claim 4, characterized in that: In the step 2, the kiln is electrically heated at a heating rate of 7.5-8.2°C / min, so that the temperature inside the kiln is rapidly raised to 950-1050°C. In the step 3, oxygen is introduced into the kiln to exhaust the air inside the kiln, and oxygen is continuously introduced to maintain the pressure inside the kiln at 100-102KPa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 2.0-3.5kW, and the temperature inside the kiln is maintained between 950 and 1200°C. The calcination oxidation reaction is carried out at 950-1200°C for 4.0h.

8. The method of preparing tungsten-containing waste into oxides using a kiln according to claim 4, characterized in that: In the step 3, oxygen is introduced into the kiln to exhaust the air in the kiln, and oxygen is continuously introduced to maintain the pressure in the kiln at 100-102 KPa. In the oxygen atmosphere, the electric heating power of the kiln is controlled to be 1.0-3.5 kW, and the temperature in the kiln is maintained between 750 and 1250° C. to calcine the oxidation reaction until the cumulative oxygen V input into the kiln in step 3 reaches 时 Equal to the amount of oxygen M obtained by completely calcining and oxidizing tungsten and M in tungsten waste 标 0.70-0.90 times of.

9. The method of preparing oxides from tungsten-containing waste using a kiln according to claim 8, characterized in that: In the step 4, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the pressure in the kiln is maintained at 100-102KPa. When the oxygen introduction amount is ≤50sccm, oxygen is introduced into the kiln in a pressurized manner, and the pressure in the kiln is maintained at 115-120KPa. In the oxygen atmosphere, the temperature in the kiln drops to 100°C and then the kiln is opened to naturally cool to room temperature to obtain calcined tungsten waste.

10. The method of preparing tungsten-containing waste into oxides using a kiln according to claim 8, characterized in that: In step 4, after the calcination oxidation reaction is completed, the electric heating of the kiln is stopped, oxygen is continuously introduced, and the internal pressure of the kiln is maintained at 100-102KPa. When the oxygen introduction amount is ≤50sccm, the exhaust pipe is opened after 0.5-1h, and low-temperature nitrogen is introduced to replace the oxygen. The nitrogen flow rate is 0.2-0.6m 3 / min, so that the temperature in the kiln quickly drops to 100℃, then the furnace is opened and naturally cooled to room temperature to obtain calcined tungsten waste.

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