Segmented temperature control and oxygen-rich deep oxidation process for waste WC and W powder

Abstract

The application discloses a waste WC and W powder segmented temperature control oxygen-enriched deep oxidation process and belongs to the technical field of oxidation processes.The process comprises the following steps: first, raw material pretreatment; second, segmented oxygen-enriched oxidation; the pretreated powder is continuously fed into a segmented temperature control oxidation furnace; third, product collection; and fourth, tail gas purification; the tail gas generated in the segmented oxygen-enriched oxidation process is treated by a three-stage purification system including water washing, alkali absorption and activated carbon adsorption and then discharged. The segmented temperature control oxidation mode is adopted to divide the oxidation process into a low-temperature pretreatment section, a medium-temperature pre-oxidation section, a high-temperature deep oxidation section and a cooling and stabilizing section, and the parameters such as the temperature, oxygen-enriched concentration and residence time of each section are accurately matched to gradually promote the oxidation reaction of WC and W. In combination with a specific proportion of oxidation accelerators, the oxidation activation energy is effectively reduced, the deep oxidation of the waste WC and W powder is realized, no unoxidized WC and W residues are detected by XRD, and the problem of insufficient oxidation in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of oxidation process technology, specifically involving a segmented temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder. Background Technology

[0002] Tungsten and its carbides (WC) are widely used in industrial fields such as cemented carbide, tungsten electrodes, and machining due to their excellent properties such as high hardness, high melting point, wear resistance, and corrosion resistance. With the continuous advancement of industrial production, a large amount of waste materials containing WC and W powder are generated, such as industrial waste cemented carbide grinding waste, waste tungsten electrodes, and tungsten processing waste. These waste materials contain a high content of tungsten resources. Tungsten is a scarce strategic metal resource with limited reserves, high mining difficulty, and high costs. Therefore, recycling and reusing waste WC and W powder can not only save resources and reduce production costs, but also reduce environmental pollution caused by waste material stockpiling, which has significant economic value and environmental significance.

[0003] Currently, the main recycling processes for waste WC and W powder include oxidation, reduction, and acid-base leaching. Oxidation is the core step in converting waste WC and W powder into WO3, which is then used in subsequent reduction processes to recover metallic tungsten. The oxidation effect directly determines the tungsten recovery rate and product purity. However, existing oxidation processes often employ single-temperature, single-oxygen-concentration oxidation methods, which have several shortcomings: First, oxidation is insufficient; WC and W in waste WC and W powder are difficult to completely convert into WO3, and the remaining unoxidized WC and W will reduce the tungsten recovery rate and affect the efficiency of subsequent recycling processes. Second, improper temperature control during oxidation can easily lead to localized overheating, causing WO3 grain growth and agglomeration, reducing product quality, or excessively low temperatures resulting in a slow oxidation rate, increasing production energy consumption and time. Third, inaccurate oxygen concentration adjustment; excessively high oxygen concentrations lead to energy waste, while excessively low concentrations cannot meet the requirements for deep oxidation. Fourth, the exhaust gas treatment effect is poor; particulate matter and NO generated during the oxidation process... X If harmful gases such as SO2 are directly emitted, it will cause serious air pollution and will not meet environmental emission standards; fifth, the raw material pretreatment is not refined enough and the impurities are not completely removed, which will affect the progress of the oxidation reaction and the purity of the product.

[0004] Furthermore, the selection and proportioning of oxidation promoters in existing processes are unreasonable, making it difficult to effectively reduce the oxidation activation energy of WC and W, further restricting the improvement of oxidation conversion rate. Therefore, developing a waste WC and W powder oxidation process that can achieve deep oxidation, improve tungsten recovery rate and product purity, reduce energy consumption, and meet environmental protection requirements has become an urgent technical problem to be solved in the industry. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems and provide a staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder, which improves the oxidation conversion rate and tungsten recovery rate, and produces high-quality products with low energy consumption and good economic efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder includes the following steps: The first step is raw material pretreatment: Waste WC / W powder is taken and crushed using airflow crushing. It is then sieved through 100-mesh and 300-mesh multi-layer vibrating screens to obtain 100-300 mesh powder. Iron filings and ceramic fragments are removed by magnetic separation and gravity separation. Oil stains are removed by organic solvent cleaning, and the powder is then dried in a hot air drying oven until the moisture content is ≤0.5%. The waste WC / W powder originates from industrial waste cemented carbide grinding waste, waste tungsten electrodes, or tungsten processing waste, with a WC content of 40-85 wt%, a W content of 10-55 wt%, and an impurity content of ≤5 wt%. The second step is segmented oxygen-enriched oxidation: the pretreated powder is continuously fed into a segmented temperature-controlled oxidation furnace. The third step is product collection: collect the oxidation product WO3, wherein the WO3 has a purity ≥99.0%, a particle size of 0.5-2.0μm, an oxidation conversion rate ≥99.5%, and a tungsten recovery rate ≥99.2%; The fourth step is exhaust gas purification: the exhaust gas generated during the segmented oxygen-enriched oxidation process is treated by a three-stage purification system of water washing + alkaline absorption + activated carbon adsorption before being discharged. After treatment, the particulate matter emission is ≤9mg / m³. 3 NO X Emissions ≤26mg / m³ 3 SO2 emissions ≤46mg / m³ 3 .

[0007] Furthermore, the powder fed into the segmented temperature-controlled oxidation furnace passes through four stages in sequence: Low-temperature pretreatment section: temperature 200-300℃, oxygen concentration 25-30 vol%, residence time 30-60 min, gas-solid ratio 8-12 m³ / s. 3 / kg; Medium-temperature pre-oxidation section: temperature 500-600℃, oxygen concentration 35-45 vol%, residence time 60-90 min, gas-solid ratio 15-20 m³ / s. 3 / kg; High-temperature deep oxidation section: temperature 800-950℃, oxygen concentration 50-70 vol%, residence time 90-120 min, gas-solid ratio 22-28 m. 3 / kg, add 0.5-1.5wt% of oxidation accelerator; the oxidation accelerator is a mixture of V2O5 and Na2CO3 in a mass ratio of 1:2-3; Cooling stabilization phase: Cool down to 150-200℃, cooling rate 5-8℃ / min, residence time 20-30min.

[0008] Furthermore, in the first step, the pressure of airflow crushing is 0.6-0.8 MPa, and the impurity removal rate is ≥99%; the drying temperature of the hot air drying oven is 120-150℃, and the drying time is 40-60 min.

[0009] Furthermore, in the second step, the pretreated powder is continuously fed into a segmented temperature-controlled oxidation furnace via a screw conveyor. The screw conveyor rotates at a speed of 15-25 r / min, and the powder feeding rate is 100-300 kg / h.

[0010] Furthermore, the segmented temperature-controlled oxidation furnace adopts a horizontal series structure, with a temperature control accuracy of ±5℃ and a gas flow control accuracy of ±0.5m³. 3 / kg.

[0011] Furthermore, the oxygen-enriched gas used in the segmented oxygen-enriched oxidation process is prepared by mixing industrial pure oxygen with air, and the purity of the industrial pure oxygen is ≥99.9%.

[0012] Furthermore, in the third step, WO3 was detected using XRD analysis and gravimetric method; oxidation conversion rate = (mass of tungsten in WO3 after oxidation / total mass of tungsten in raw material) × 100%, tungsten recovery rate = (mass of tungsten in collected WO3 / total mass of tungsten in raw material) × 100%.

[0013] Furthermore, in the first step, ethanol or acetone is used as the organic solvent, and the cleaning time is 10-20 minutes to ensure that the oil stains are completely removed.

[0014] Furthermore, in the second step, the amount of oxidation accelerator added in the high-temperature deep oxidation section is 0.5-1.5 wt%, and it increases with the increase of WC content.

[0015] The beneficial effects of this invention are as follows: (1) The segmented temperature-controlled oxidation mode is adopted, which divides the oxidation process into a low-temperature pretreatment section, a medium-temperature pre-oxidation section, a high-temperature deep oxidation section and a cooling and stabilization section. The parameters such as temperature, oxygen concentration and residence time of each section are precisely matched to gradually promote the oxidation reaction of WC and W. Combined with a specific ratio of oxidation promoter (a mixture of V2O5 and Na2CO3), the oxidation activation energy is effectively reduced, and the deep oxidation of waste WC and W powder is achieved. The oxidation conversion rate can reach more than 99.5%, the tungsten recovery rate can reach more than 99.2%, and XRD detection shows no unoxidized WC and W residues, which completely solves the problem of insufficient oxidation in the existing process.

[0016] (2) By precisely controlling the temperature and cooling rate of each stage, the growth and agglomeration of WO3 grains are avoided. At the same time, the fine raw material pretreatment removes impurities such as iron filings, ceramic fragments, and oil stains, so that the purity of the final product WO3 can reach more than 99.0%, the particle size is controlled between 0.5-2.0μm, and the packing density is uniform, which meets the requirements of the subsequent reduction and recovery process for WO3 quality. It can be directly used for the preparation of metallic tungsten, improving the quality of subsequent products.

[0017] (3) The segmented temperature control design can precisely adjust the temperature and oxygen concentration according to the different stages of the oxidation reaction, avoiding energy waste caused by single high-temperature oxidation; the oxygen-enriched gas is prepared by mixing industrial pure oxygen with air, which reduces the cost of oxygen use compared with pure oxygen oxidation; at the same time, the raw material pretreatment adopts efficient processes such as airflow crushing, multi-layer screening, magnetic separation and gravity separation, and the impurity removal rate can reach more than 99%, which reduces the interference of impurities on the oxidation reaction, reduces production energy consumption and subsequent processing costs, and improves the economic efficiency of the process. Attached Figure Description

[0018] Figure 1 This is a diagram of the segmented temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] refer to Figure 1 As shown in the figure, this embodiment provides a segmented temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder.

[0021] In the following embodiments, the waste WC / W powder used is derived from industrial waste cemented carbide grinding waste, waste tungsten electrodes, or tungsten processing waste. Testing revealed a WC content of 40-85 wt%, a W content of 10-55 wt%, and an impurity content of ≤5 wt%. The oxidation promoter is a mixture of V₂O₅ and Na₂CO₃ in a mass ratio of 1:2-3. The oxygen-enriched gas is prepared by mixing industrial pure oxygen (purity ≥99.9%) with air. The segmented temperature-controlled oxidation furnace adopts a horizontal series structure with a temperature control accuracy of ±5℃ and a gas flow control accuracy of ±0.5m³. 3 / kg; the exhaust gas purification device adopts a three-stage purification system of water washing + alkaline absorption + activated carbon adsorption; the oxidation product WO3 is detected by XRD analysis and gravimetric method, the oxidation conversion rate = (mass of tungsten in WO3 after oxidation / total mass of tungsten in raw materials) × 100%, and the tungsten recovery rate = (mass of tungsten in collected WO3 / total mass of tungsten in raw materials) × 100%.

[0022] Example 1 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 40wt%, W content 55wt%, impurity content 3wt%), crush it by air crushing at a crushing pressure of 0.6MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99%. Send the powder into a hot air drying oven and dry it at 120℃ for 60min. The moisture content after drying is 0.5%.

[0023] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 100 kg / h via a screw conveyor (speed 15 r / min), passing through each segment in sequence: low temperature pretreatment segment (200℃, oxygen concentration 25 vol%, residence time 60 min, gas-solid ratio 8 m). 3 / kg); Medium-temperature pre-oxidation section (500℃, oxygen concentration 35 vol%, residence time 90 min, gas-solid ratio 15 m). 3 / kg); High-temperature deep oxidation section (800℃, oxygen concentration 50 vol%, residence time 120 min, gas-solid ratio 22 m). 3 / kg, with the addition of 0.5wt% oxidation promoter, and a V2O5 to Na2CO3 mass ratio of 1:2; cooling stabilization phase (cooling to 150℃, cooling rate 5℃ / min, residence time 30min).

[0024] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.0%, the particle size was 0.5-2.0μm, and the bulk density was 1.2g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.5%, and tungsten recovery rate was 99.2%.

[0025] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 8 mg / m³. 3 NO X Emissions 25mg / m³ 3 SO2 emissions 45 mg / m³ 3 It meets environmental protection standards.

[0026] Example 2 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 50wt%, W content 45wt%, impurity content 2.5wt%), crush it by air jet crushing at a crushing pressure of 0.65MPa, and screen it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.2%. Send the powder into a hot air drying oven and dry it at 130℃ for 50min. The moisture content after drying is 0.4%.

[0027] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 150 kg / h via a screw conveyor (speed 18 r / min), passing through each segment in sequence: low temperature pretreatment segment (220℃, oxygen concentration 26 vol%, residence time 50 min, gas-solid ratio 9 m). 3 / kg); Medium-temperature pre-oxidation section (520℃, oxygen concentration 38 vol%, residence time 80 min, gas-solid ratio 16 m). 3 / kg); High-temperature deep oxidation section (830℃, oxygen concentration 55 vol%, residence time 110 min, gas-solid ratio 23 m). 3 / kg, with the addition of 0.8wt% oxidation promoter, and a V2O5 to Na2CO3 mass ratio of 1:2.2; cooling stabilization phase (cooling to 160℃, cooling rate 6℃ / min, residence time 28min).

[0028] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.1%, the particle size was 0.5-2.0 μm, and the bulk density was 1.3 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.6%, and tungsten recovery rate was 99.3%.

[0029] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 7 mg / m³. 3 NO X Emissions 24mg / m³ 3 SO2 emissions: 42 mg / m³ 3 It meets environmental protection standards.

[0030] Example 3 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 60wt%, W content 35wt%, impurity content 2wt%), crush it by air crushing at a crushing pressure of 0.7MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.3%. Send the powder into a hot air drying oven and dry it at 135℃ for 45min. The moisture content after drying is 0.35%.

[0031] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 200 kg / h via a screw conveyor (speed 20 r / min), passing through each segment in sequence: low temperature pretreatment segment (240℃, oxygen concentration 27 vol%, residence time 45 min, gas-solid ratio 10 m). 3 / kg); Medium-temperature pre-oxidation section (540℃, oxygen concentration 40 vol%, residence time 75 min, gas-solid ratio 17 m). 3 / kg); High-temperature deep oxidation section (860℃, oxygen concentration 60 vol%, residence time 105 min, gas-solid ratio 24 m). 3 / kg, with 1.0wt% added oxidation promoter, V2O5 to Na2CO3 mass ratio 1:2.5; cooling stabilization section (cooling to 170℃, cooling rate 6℃ / min, residence time 26min).

[0032] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.2%, the particle size was 0.5-2.0 μm, and the bulk density was 1.35 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.7%, and tungsten recovery rate was 99.4%.

[0033] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 6 mg / m³. 3 NO X Emissions 23mg / m³ 3 SO2 emissions 40 mg / m³ 3 It meets environmental protection standards.

[0034] Example 4 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 70wt%, W content 25wt%, impurity content 1.5wt%), crush it by air jet crushing at a crushing pressure of 0.7MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.4%. Send the powder into a hot air drying oven and dry it at 140℃ for 45min. The moisture content after drying is 0.3%.

[0035] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 200 kg / h via a screw conveyor (speed 20 r / min), passing through each segment in sequence: low temperature pretreatment segment (250℃, oxygen concentration 28 vol%, residence time 40 min, gas-solid ratio 10 m). 3 / kg); Medium-temperature pre-oxidation section (550℃, oxygen concentration 40 vol%, residence time 70 min, gas-solid ratio 18 m). 3 / kg); High-temperature deep oxidation section (880℃, oxygen concentration 60 vol%, residence time 100 min, gas-solid ratio 25 m). 3 / kg, with 1.0wt% oxidation promoter added, V2O5 to Na2CO3 mass ratio 1:2.5; cooling stabilization section (cooling to 175℃, cooling rate 7℃ / min, residence time 25min).

[0036] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.2%, the particle size was 0.5-2.0 μm, and the bulk density was 1.4 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.7%, and tungsten recovery rate was 99.4%.

[0037] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 5mg / m³. 3 NO X Emissions 22mg / m³ 3 SO2 emissions: 38 mg / m³ 3 It meets environmental protection standards.

[0038] Example 5 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 80wt%, W content 15wt%, impurity content 1wt%), crush it by air jet crushing at a crushing pressure of 0.75MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.5%. Send the powder into a hot air drying oven and dry it at 140℃ for 40min. The moisture content after drying is 0.25%.

[0039] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 250 kg / h via a screw conveyor (speed 22 r / min), passing through the following segments in sequence: low temperature pretreatment segment (260℃, oxygen concentration 28 vol%, residence time 38 min, gas-solid ratio 11 m). 3 / kg); Medium-temperature pre-oxidation section (560℃, oxygen concentration 42 vol%, residence time 68 min, gas-solid ratio 18 m). 3 / kg); High-temperature deep oxidation section (900℃, oxygen concentration 65 vol%, residence time 98 min, gas-solid ratio 26 m). 3 / kg, with 1.2wt% added oxidation promoter, V2O5 to Na2CO3 mass ratio 1:2.8; cooling stabilization section (cooling to 180℃, cooling rate 7℃ / min, residence time 24min).

[0040] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.3%, the particle size was 0.5-2.0 μm, and the bulk density was 1.4 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.8%, and tungsten recovery rate was 99.5%.

[0041] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 4 mg / m³. 3 NO X Emissions 21 mg / m³ 3 SO2 emissions: 35 mg / m³ 3 It meets environmental protection standards.

[0042] Example 6 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 85wt%, W content 10wt%, impurity content 0.5wt%), crush it by air jet crushing at a crushing pressure of 0.8MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.6%. Send the powder into a hot air drying oven and dry it at 150℃ for 40min. The moisture content after drying is 0.2%.

[0043] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 300 kg / h via a screw conveyor (speed 25 r / min), passing through the following segments in sequence: low temperature pretreatment segment (300℃, oxygen concentration 30 vol%, residence time 30 min, gas-solid ratio 12 m). 3 / kg); Medium-temperature pre-oxidation section (600℃, oxygen concentration 45 vol%, residence time 60 min, gas-solid ratio 20 m³ / kg); 3 / kg); High-temperature deep oxidation section (950℃, oxygen concentration 70 vol%, residence time 90 min, gas-solid ratio 28 m). 3 / kg, with 1.5wt% oxidation promoter added, V2O5 to Na2CO3 mass ratio 1:3; cooling stabilization section (cooling to 200℃, cooling rate 8℃ / min, residence time 20min).

[0044] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.5%, the particle size was 0.5-2.0 μm, and the bulk density was 1.5 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.9%, and tungsten recovery rate was 99.6%.

[0045] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 3mg / m³. 3 NOx emissions 20 mg / m³ 3 SO2 emissions 30 mg / m³ 3 It meets environmental protection standards.

[0046] Example 7 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 55wt%, W content 40wt%, impurity content 4wt%), crush it by air jet crushing at a crushing pressure of 0.65MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.1%. Send the powder into a hot air drying oven and dry it at 125℃ for 55min. The moisture content after drying is 0.45%.

[0047] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 120 kg / h via a screw conveyor (speed 16 r / min), passing through the following segments in sequence: low temperature pretreatment segment (210℃, oxygen concentration 25 vol%, residence time 55 min, gas-solid ratio 8.5 m 3 / kg); Medium-temperature pre-oxidation section (510℃, oxygen concentration 36 vol%, residence time 85 min, gas-solid ratio 15.5 m 3 / kg); High-temperature deep oxidation section (820℃, oxygen concentration 52 vol%, residence time 115 min, gas-solid ratio 22.5 m 3 / kg, with the addition of 0.6wt% oxidation promoter, and a V2O5 to Na2CO3 mass ratio of 1:2.1; cooling stabilization phase (cooling to 155℃, cooling rate 5.5℃ / min, residence time 29min).

[0048] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.0%, the particle size was 0.5-2.0μm, and the bulk density was 1.25g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.5%, and tungsten recovery rate was 99.2%.

[0049] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 9 mg / m³. 3 NO X Emissions 26mg / m³ 3 SO2 emissions: 46 mg / m³ 3 It meets environmental protection standards.

[0050] Example 8 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 65wt%, W content 30wt%, impurity content 3.5wt%), crush it by air jet crushing at a crushing pressure of 0.7MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.2%. Send the powder into a hot air drying oven and dry it at 130℃ for 50min. The moisture content after drying is 0.35%.

[0051] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 180 kg / h via a screw conveyor (speed 19 r / min), passing through the following segments in sequence: low temperature pretreatment segment (230℃, oxygen concentration 27 vol%, residence time 48 min, gas-solid ratio 9.5 m). 3 / kg); Medium-temperature pre-oxidation section (530℃, oxygen concentration 39 vol%, residence time 78 min, gas-solid ratio 16.5 m 3 / kg); High-temperature deep oxidation section (850℃, oxygen concentration 58 vol%, residence time 108 min, gas-solid ratio 23.5 m 3 / kg, with the addition of 0.9wt% oxidation promoter, and a V2O5 to Na2CO3 mass ratio of 1:2.4; cooling stabilization phase (cooling to 165℃, cooling rate 6.5℃ / min, residence time 27min).

[0052] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.1%, the particle size was 0.5-2.0 μm, and the bulk density was 1.3 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.6%, and tungsten recovery rate was 99.3%.

[0053] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 6 mg / m³. 3 NO X Emissions 23mg / m³ 3 SO2 emissions: 41 mg / m³ 3 It meets environmental protection standards.

[0054] Example 9 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 75wt%, W content 20wt%, impurity content 2.5wt%), crush it by air jet crushing at a crushing pressure of 0.75MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.4%. Send the powder into a hot air drying oven and dry it at 140℃ for 45min. The moisture content after drying is 0.3%.

[0055] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 220 kg / h via a screw conveyor (speed 21 r / min), passing through the following segments in sequence: low temperature pretreatment segment (270℃, oxygen concentration 29 vol%, residence time 36 min, gas-solid ratio 11.5 m 3 / kg); Medium-temperature pre-oxidation section (570℃, oxygen concentration 43 vol%, residence time 66 min, gas-solid ratio 18.5 m 3 / kg); High-temperature deep oxidation section (910℃, oxygen concentration 62 vol%, residence time 96 min, gas-solid ratio 26.5 m 3 / kg, with 1.1wt% oxidation promoter added, V2O5 to Na2CO3 mass ratio 1:2.6; cooling stabilization section (cooling to 185℃, cooling rate 7.5℃ / min, residence time 23min).

[0056] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.3%, the particle size was 0.5-2.0 μm, and the bulk density was 1.4 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.8%, and tungsten recovery rate was 99.5%.

[0057] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 4 mg / m³. 3 NO X Emissions 21 mg / m³ 3 SO2 emissions: 36 mg / m³ 3 It meets environmental protection standards.

[0058] Example 10 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 45wt%, W content 50wt%, impurity content 3.5wt%), crush it by air jet crushing at a crushing pressure of 0.6MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.0%. Send the powder into a hot air drying oven and dry it at 120℃ for 60min. The moisture content after drying is 0.5%.

[0059] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 110 kg / h via a screw conveyor (speed 15 r / min), passing through the following segments in sequence: low temperature pretreatment segment (205℃, oxygen concentration 26 vol%, residence time 58 min, gas-solid ratio 8.2 m). 3 / kg); Medium-temperature pre-oxidation section (505℃, oxygen concentration 37 vol%, residence time 88 min, gas-solid ratio 15.2 m 3 / kg); High-temperature deep oxidation section (810℃, oxygen concentration 51 vol%, residence time 118 min, gas-solid ratio 22.2 m 3 / kg, with the addition of 0.55wt% oxidation promoter, and a V2O5 to Na2CO3 mass ratio of 1:2.0; cooling stabilization phase (cooling to 152℃, cooling rate 5.2℃ / min, residence time 29min).

[0060] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.0%, the particle size was 0.5-2.0μm, and the bulk density was 1.22g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.5%, and tungsten recovery rate was 99.2%.

[0061] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 8.5 mg / m³. 3 NO X Emissions: 25.5 mg / m³ 3 SO2 emissions: 45.5 mg / m³ 3 It meets environmental protection standards.

[0062] Example 11 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 70wt%, W content 28wt%, impurity content 1.8wt%), crush it by air jet crushing at a crushing pressure of 0.7MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.3%. Send the powder into a hot air drying oven and dry it at 135℃ for 48min. The moisture content after drying is 0.32%.

[0063] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 210 kg / h via a screw conveyor (speed 20 r / min), passing through the following segments in sequence: low temperature pretreatment segment (250℃, oxygen concentration 28 vol%, residence time 42 min, gas-solid ratio 10.5 m 3 / kg); Medium-temperature pre-oxidation section (550℃, oxygen concentration 41 vol%, residence time 72 min, gas-solid ratio 17.5 m 3 / kg); High-temperature deep oxidation section (880℃, oxygen concentration 60 vol%, residence time 102 min, gas-solid ratio 24.5 m 3 / kg, with 1.0wt% added oxidation promoter, V2O5 to Na2CO3 mass ratio 1:2.5; cooling stabilization section (cooling to 175℃, cooling rate 6.8℃ / min, residence time 25min).

[0064] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.2%, the particle size was 0.5-2.0 μm, and the bulk density was 1.38 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.7%, and tungsten recovery rate was 99.4%.

[0065] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 5.5 mg / m³. 3 NO X Emissions: 22.5 mg / m³ 3 SO2 emissions: 39 mg / m³ 3 It meets environmental protection standards.

[0066] Example 12 This embodiment provides a segmented, temperature-controlled, oxygen-enriched deep oxidation process for waste WC / W powder, the specific steps of which are as follows: (1) Raw material pretreatment: Take waste WC / W powder (WC content 82wt%, W content 13wt%, impurity content 0.8wt%), crush it by air jet crushing at a crushing pressure of 0.8MPa, and sieve it through a multi-layer vibrating screen of 100 mesh and 300 mesh to obtain 100-300 mesh powder. Remove iron filings and ceramic fragments by magnetic separation and gravity separation, and remove oil stains by organic solvent cleaning. The impurity removal rate is 99.5%. Send the powder into a hot air drying oven and dry it at 145℃ for 42min. The moisture content after drying is 0.22%.

[0067] (2) Segmented oxygen-enriched oxidation: The pretreated powder is continuously fed into the segmented temperature-controlled oxidation furnace at a rate of 280 kg / h via a screw conveyor (speed 24 r / min), passing through the following segments in sequence: low temperature pretreatment segment (280℃, oxygen concentration 29 vol%, residence time 32 min, gas-solid ratio 11.8 m 3 / kg); Medium-temperature pre-oxidation section (580℃, oxygen concentration 44 vol%, residence time 64 min, gas-solid ratio 19 m). 3 / kg); High-temperature deep oxidation section (930℃, oxygen concentration 68 vol%, residence time 94 min, gas-solid ratio 27 m). 3 / kg, with 1.4wt% added oxidation promoter, V2O5 to Na2CO3 mass ratio 1:2.9; cooling stabilization section (cooling to 190℃, cooling rate 7.8℃ / min, residence time 22min).

[0068] (3) Product collection: The oxidation product WO3 was collected. After testing, the purity of WO3 was 99.4%, the particle size was 0.5-2.0 μm, and the bulk density was 1.45 g / cm³. 3 XRD analysis showed no unoxidized WC and W; oxidation conversion rate was 99.8%, and tungsten recovery rate was 99.5%.

[0069] (4) Exhaust gas purification: After three-stage purification treatment, the particulate matter emission is 3.5 mg / m³. 3 NO X Emissions: 20.5 mg / m³ 3 SO2 emissions: 32 mg / m³ 3 It meets environmental protection standards.

Claims

1. A staged, temperature-controlled, oxygen-enriched deep oxidation process for waste WC and W powder, characterized in that, Includes the following steps: The first step is raw material pretreatment: Waste WC / W powder is taken and crushed using airflow crushing. It is then sieved through 100-mesh and 300-mesh multi-layer vibrating screens to obtain 100-300 mesh powder. Iron filings and ceramic fragments are removed by magnetic separation and gravity separation. Oil stains are removed by organic solvent cleaning, and the powder is then dried in a hot air drying oven until the moisture content is ≤0.5%. The waste WC / W powder originates from industrial waste cemented carbide grinding waste, waste tungsten electrodes, or tungsten processing waste, with a WC content of 40-85 wt%, a W content of 10-55 wt%, and an impurity content of ≤5 wt%. The second step is segmented oxygen-enriched oxidation: the pretreated powder is continuously fed into a segmented temperature-controlled oxidation furnace. The third step is product collection: collect the oxidation product WO3, wherein the WO3 has a purity ≥99.0%, a particle size of 0.5-2.0μm, an oxidation conversion rate ≥99.5%, and a tungsten recovery rate ≥99.2%; The fourth step is exhaust gas purification: the exhaust gas generated during the segmented oxygen-enriched oxidation process is treated by a three-stage purification system of water washing + alkaline absorption + activated carbon adsorption before being discharged. After treatment, the particulate matter emission is ≤9mg / m³. 3 NO X Emissions ≤26mg / m³ 3 SO2 emissions ≤46mg / m³ 3 .

2. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, The powder fed into the segmented temperature-controlled oxidation furnace passes through four stages in sequence: Low-temperature pretreatment section: temperature 200-300℃, oxygen concentration 25-30 vol%, residence time 30-60 min, gas-solid ratio 8-12 m³ / s. 3 / kg; Medium-temperature pre-oxidation section: temperature 500-600℃, oxygen concentration 35-45 vol%, residence time 60-90 min, gas-solid ratio 15-20 m³ / s. 3 / kg; High-temperature deep oxidation section: temperature 800-950℃, oxygen concentration 50-70 vol%, residence time 90-120 min, gas-solid ratio 22-28 m. 3 / kg, add 0.5-1.5wt% of oxidation accelerator; the oxidation accelerator is a mixture of V2O5 and Na2CO3 in a mass ratio of 1:2-3; Cooling stabilization phase: Cool down to 150-200℃, cooling rate 5-8℃ / min, residence time 20-30min.

3. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, In the first step, the pressure of airflow crushing is 0.6-0.8 MPa, and the impurity removal rate is ≥99%; the drying temperature of the hot air drying oven is 120-150℃, and the drying time is 40-60 min.

4. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, In the second step, the pretreated powder is continuously fed into a segmented temperature-controlled oxidation furnace via a screw conveyor. The screw conveyor rotates at a speed of 15-25 r / min, and the powder feeding rate is 100-300 kg / h.

5. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, The segmented temperature-controlled oxidation furnace adopts a horizontal series structure, with a temperature control accuracy of ±5℃ and a gas flow control accuracy of ±0.5m³. 3 / kg.

6. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, The oxygen-enriched gas used in the segmented oxygen-enriched oxidation process is prepared by mixing industrial pure oxygen with air, and the purity of the industrial pure oxygen is ≥99.9%.

7. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 6, characterized in that, In the third step, WO3 was detected using XRD analysis and gravimetric method; oxidation conversion rate = (mass of tungsten in WO3 after oxidation / total mass of tungsten in raw material) × 100%, tungsten recovery rate = (mass of tungsten in collected WO3 / total mass of tungsten in raw material) × 100%.

8. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, In the first step, use ethanol or acetone as the organic solvent and clean for 10-20 minutes to ensure that the oil stains are completely removed.

9. The staged temperature-controlled oxygen-enriched deep oxidation process for waste WC and W powder according to claim 1, characterized in that, In the second step, the amount of oxidation accelerator added in the high-temperature deep oxidation section is 0.5-1.5 wt%, and it increases with the increase of WC content.

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