Method for preparing tungsten compound from artificial tungsten ore
By using low-concentration sulfuric acid leaching and impurity removal technology, the problems of high acid consumption and difficult filtration in traditional tungsten smelting have been solved, enabling the clean and efficient recovery of low-grade tungsten resources and reducing costs and environmental pressure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CENT SOUTH UNIV
- Filing Date
- 2026-02-11
- Publication Date
- 2026-05-15
AI Technical Summary
Traditional tungsten smelting processes suffer from problems such as high acid consumption, difficult filtration, severe tungsten loss, and significant environmental pressure, and are particularly ineffective in processing low-grade tungsten resources.
Tungsten was leached by reacting artificial tungsten ore with low-concentration sulfuric acid, with the pH value controlled at 0.2~4.0, the temperature at 25~100℃, the liquid-to-solid ratio at 1:1~10:1, and the reaction time at 30min~6h. Subsequently, a purifying agent was added to remove impurity ions, resulting in a pure metatungstic acid solution.
Significantly reduce acid consumption, minimize tungsten loss, simplify process flow, reduce energy consumption, reduce pollutant emissions, improve tungsten recovery rate, and achieve clean and efficient tungsten resource recycling.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for preparing tungsten compounds from synthetic tungsten ore. Background Technology
[0002] Tungsten is an important strategic rare metal, widely used in cemented carbide, aerospace, and electronic information industries. Traditional tungsten smelting processes for wolframite and scheelite primarily employ alkaline leaching or alkaline melting to convert tungsten into soluble sodium tungstate. Tungsten is then extracted using ion exchange or dissolution extraction, but this process simultaneously discharges large amounts of saline wastewater. To address the problems arising from the traditional alkaline tungsten smelting process, acid processes have also been used to treat tungsten ore. The acid decomposition process for tungsten ore requires strongly acidic conditions to convert tungsten into insoluble flavonoid acid (H₂WO₄) precipitate, while impurities such as calcium, iron, and manganese are separated into the solution. This method has significant drawbacks: ① Extremely high acid consumption, requiring large amounts of concentrated hydrochloric acid; ② The generated tungstic acid is in the form of fine colloidal particles, making filtration and washing difficult, resulting in significant tungsten loss; ③ It generates large amounts of chlorine-containing wastewater and chlorine gas, placing significant environmental pressure on the environment; ④ Tungstic acid requires secondary alkaline dissolution before entering subsequent ion exchange or extraction processes, resulting in additional alkali consumption and a lengthy process; ⑤ It is ineffective at decomposing other sparingly soluble tungstates containing lead, barium, rare earth elements, etc., leaving them as insoluble tungstic acid residues.
[0003] Although improved technologies such as mechanical activation, seed crystal control, and additives have emerged in recent years, they still essentially rely on the traditional route of "tungstic acid precipitation under high-concentration acid conditions," failing to fundamentally reduce acid consumption and solve filtration problems. Against this backdrop, this invention, through systematic research, discovers that highly efficient soluble leaching of synthetic tungsten ore can be achieved under low-concentration acid conditions, significantly reducing acid consumption and completely overcoming the bottlenecks of traditional tungstic acid precipitation processes. This provides a completely new technical route for the clean and efficient recovery and preparation of qualified tungsten compounds from low-grade and secondary tungsten resources. Summary of the Invention
[0004] In view of the above shortcomings, the present invention uses sulfuric acid to react with artificial tungsten ore to leach tungsten, and the resulting metatungstic acid leachate can be purified to obtain a pure metatungstic acid solution.
[0005] To achieve the above-mentioned technical effects, the present invention adopts the following technical means:
[0006] This invention first discloses a method for preparing tungsten compounds from synthetic tungsten ore, comprising:
[0007] (1) Preparation of artificial tungsten ore: Prepare artificial tungsten ore, wherein the artificial tungsten ore is selected from any one or a mixture of CaWO4, Ca2WO5, Ca3WO6, PbWO4, and BaWO4;
[0008] (2) Sulfuric acid leaching: The artificial tungsten ore is mixed with sulfuric acid for leaching reaction. The reaction conditions are controlled as follows: pH value 0.2~4.0, temperature 25~100℃, reaction time 30min~6h, liquid-solid ratio 1:1~10:1. After the reaction is completed, metatungstic acid leaching solution is obtained.
[0009] (3) Impurity removal and purification: Add a purifying agent to the metatungstic acid leachate and react for 1 to 60 minutes to remove impurity ions and obtain a pure metatungstic acid solution.
[0010] Further, the artificial tungsten ore described in step (1) is synthesized using any of the following methods:
[0011] ① Precipitation reaction method: Add a soluble salt, oxide or hydroxide containing the target metal cation to an aqueous solution of tungstate to produce artificial tungsten ore through a precipitation reaction;
[0012] ② Aqueous phase transformation method: using solid tungstic acid or tungsten oxide as the tungsten source, it is mixed with a slightly soluble or sparingly soluble compound of the target metal in an aqueous medium, and reacted under heating or stirring conditions to transform into artificial tungsten ore; the target metal is any one or more of Ca, Pb, and Ba; the slightly soluble or sparingly soluble compound is selected from any one of the hydroxides, oxides, carbonates, and basic carbonates of the target metal;
[0013] ③ High-temperature roasting method: Tungsten source is mixed with oxides or salts of the target metal and roasted at high temperature to synthesize artificial tungsten ore; the tungsten source is selected from any one or more of tungsten oxide, tungstic acid, scheelite, and wolframite; the target metal is any one or more of Ca, Pb, and Ba;
[0014] ④ Special process synthesis method: Synthetic artificial tungsten ore is synthesized by sol-gel process or hydrothermal reactor reaction.
[0015] Further, the tungstate in step ① is selected from any one of sodium tungstate, ammonium tungstate, and potassium tungstate; the target metal cation is Ca. 2+ Pb 2+ Ba 2+ Any one or more of the following.
[0016] Further, the target metal in step ② is any one or more of Ca, Pb, and Ba; the slightly soluble or sparingly soluble compound is selected from any one of the hydroxides, oxides, carbonates, and basic carbonates of the target metal.
[0017] Furthermore, the tungsten source in step ③ is selected from any one or more of tungsten oxide, tungstic acid, scheelite, and wolframite; the target metal is any one or more of Ca, Pb, and Ba.
[0018] Furthermore, the leaching reaction in step (2) is carried out under stirring conditions, with a stirring rate of 100~600 rpm.
[0019] Furthermore, the metatungstic acid leachate obtained in step (2) can be used to extract tungsten compounds by ion exchange or dissolution extraction, wherein:
[0020] The ion exchange resin is a macroporous weakly basic anion exchange resin.
[0021] The extractant is selected from amine extractants or neutral phosphorus extractants.
[0022] Furthermore, the purifying agent in step (3) is selected from any one of cation exchange resin, chelating resin, and organophosphorus extractant.
[0023] Further, the impurity ions in step (3) include: Fe 3+ Al 3+ Ca 2+ Pb 2+ Ba 2+ One or more of phosphorus, arsenic, and silicon; the metatungstic acid leachate is purified to obtain a pure metatungstic acid solution.
[0024] The present invention also discloses a pure metatungstic acid solution prepared according to any of the above methods.
[0025] The present invention also discloses the application of the pure metatungstic acid solution described above in the preparation of solid metatungstic acid, phosphotungstic acid, ammonium phosphotungstate, tungsten oxide, ammonium metatungstate, ammonium paratungstate, and tungstic acid.
[0026] Further, the preparation of solid metatungstic acid includes the following method: drying a pure metatungstic acid solution at 30~90℃ to obtain solid metatungstic acid;
[0027] Further, the preparation of phosphotungstic acid includes the following method: adding phosphoric acid to a pure metatungstic acid solution, controlling the molar ratio of W to P to be 12:1, stirring the reaction at 20~100℃ for 10 min~4 hours, and concentrating and crystallizing to obtain phosphotungstic acid.
[0028] Furthermore, the preparation of ammonium phosphotungstate includes the following method: adding ammonium phosphate to a pure metatungstic acid solution, controlling the molar ratio of W to P to be 12:1, stirring and reacting at 20~100℃ for 10 min~4 hours, and directly precipitating ammonium phosphotungstate crystals.
[0029] Further, the preparation of ammonium metatungstate includes the following method: adding ammonia water to a pure metatungstate solution, adjusting the pH of the solution to 3-5, stirring the reaction at 20-100℃ for 10 min-4 hours, and spray drying to obtain ammonium metatungstate crystals.
[0030] Furthermore, the preparation of ammonium paratungstate includes the following method: adding ammonia water to a pure metatungstic acid solution, adjusting the pH of the solution to 5-7, stirring the reaction at 20-100℃ for 10 min-4 hours, and directly precipitating ammonium paratungstate (APT) crystals.
[0031] Further, the preparation of tungstic acid or tungsten oxide includes the following method: adding 0~1 mol / L hydrogen peroxide and 0~2 mol / L acid to the pure metatungstic acid solution, wherein the acid is selected from any one of sulfuric acid, hydrochloric acid, nitric acid, and oxalic acid; and then hydrothermally treating at 100~200℃ for 0.5~24 hours to obtain tungstic acid or tungsten oxide.
[0032] Furthermore, the preparation of tungsten oxide includes the following steps:
[0033] The pure metatungstic acid solution was dried at 30-90℃ to obtain solid metatungstic acid.
[0034] Solid metatungstic acid is calcined in air at 300-900°C for 1-4 hours to obtain hexagonal tungsten oxide or tungsten trioxide.
[0035] Furthermore, the preparation of phosphotungstic acid includes the following steps:
[0036] Phosphoric acid was added to a pure metatungstic acid solution, and the molar ratio of W to P was controlled at 12:1. The mixture was stirred at 20~100℃ for 10 min~4 hours, and then crystallized to obtain phosphotungstic acid.
[0037] Furthermore, the preparation of ammonium phosphotungstenate includes the following steps:
[0038] Ammonium phosphate was added to a pure metatungstic acid solution, and the molar ratio of W to P was controlled at 12:1. The mixture was stirred at 20~100℃ for 10 min to 4 hours to directly precipitate ammonium phosphotungstate crystals.
[0039] Furthermore, the preparation of ammonium metatungstate includes the following steps:
[0040] Ammonia was added to a pure metatungstic acid solution to adjust the pH to 3-5. The solution was stirred and reacted at 20-100℃ for 10 min-4 hours, and then spray-dried to obtain ammonium metatungstate crystals.
[0041] Furthermore, the preparation of ammonium paratungstate (APT) includes the following steps:
[0042] Add ammonia to a pure metatungstic acid solution to adjust the pH to 5-7, and stir the reaction at 20-100℃ for 10 min-4 hours to directly precipitate ammonium paratungstate (APT) crystals.
[0043] Furthermore, the preparation of tungstic acid or tungsten oxide includes the following steps:
[0044] The steps for preparing tungstic acid or tungsten oxide include: adding 0-1 mol / L hydrogen peroxide and 0-2 mol / L acid to the pure metatungstic acid solution, wherein the acid is selected from any one of sulfuric acid, hydrochloric acid, nitric acid, and oxalic acid; and then hydrothermally treating the solution at 100-200°C for 0.5-24 hours to obtain tungstic acid or tungsten oxide.
[0045] The present invention also discloses a metatungstate leaching solution prepared according to any of the above methods.
[0046] This invention also discloses the application of the above-described metatungstic acid leachate in the preparation of tungsten compounds, comprising:
[0047] Tungsten compounds are prepared by extracting tungsten from metatungstic acid leachate using ion exchange or dissolution extraction, wherein:
[0048] The ion exchange resin is a macroporous weakly basic anion exchange resin.
[0049] The extractant is selected from amine extractants or neutral phosphorus extractants.
[0050] The beneficial effects of this invention are as follows:
[0051] 1. This invention significantly reduces acid consumption and saves costs: It eliminates the need for high-concentration acids required in traditional processes, enabling efficient soluble leaching of tungsten under low-concentration acid conditions. This eliminates the need for large amounts of concentrated hydrochloric acid, significantly reducing acid consumption and raw material costs. It provides a completely new technical route, departing from the traditional path of "tungstic acid precipitation under high-concentration acid conditions," offering an innovative technical solution for the clean and efficient recovery of low-grade and secondary tungsten resources, and contributing to the sustainable development of the tungsten smelting industry.
[0052] 2. This invention solves the filtration problem and reduces tungsten loss: Tungsten enters the leachate in a soluble form, eliminating the need for cumbersome filtration and washing processes. This completely solves the filtration difficulties of traditional processes, significantly reducing tungsten loss and increasing tungsten recovery rate. It abandons the hydrochloric acid decomposition process, producing no large amounts of chlorine-containing wastewater or chlorine gas, reducing pollutant emissions at the source, alleviating environmental protection pressure, and meeting clean production requirements. Simultaneously, it simplifies the process flow, reduces energy consumption, and eliminates the need for secondary alkaline dissolution of tungstic acid, directly obtaining a metatungstic acid solution that can be further purified. This shortens the production process, reduces additional alkali consumption and corresponding energy consumption, and improves production efficiency.
[0053] 3. This invention constructs a clean and short-process technical route of "artificial tungsten ore → metatungstic acid solution → multi-component tungsten chemicals", realizing highly flexible and modular production from raw materials to end products, and providing a new paradigm for the high-value utilization of tungsten resources. Detailed Implementation
[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0055] Example 1
[0056] Synthesis of artificial tungsten ore by precipitation reaction and tungsten leaching purification
[0057] (1) Preparation of artificial tungsten ore: Take 1000 mL of 0.5 mol / L sodium tungstate aqueous solution and place it in a 2000 mL beaker. Under stirring conditions of 25 ℃ and 300 r / min, slowly add 850 mL of 0.6 mol / L calcium chloride solution (theoretical Ca) dropwise. 2+ :WO4 2- = 1.02:1), after the addition was completed, the reaction was stirred for 2 h. After the precipitate was allowed to stand and separate into layers, it was filtered. The filter cake was washed with deionized water until no sodium ions were detected in the filtrate (no turbidity was detected by AgNO3 detection). It was dried at 105 ℃ for 4 h to obtain white artificial tungsten ore CaWO4 powder with a yield of 99.6%. XRD showed that it was a pure phase scheelite structure.
[0058] (2) Sulfuric acid leaching: Take 50 g of the above CaWO4 powder, add 250 mL of 1 mol / L sulfuric acid solution (liquid-solid ratio 5:1), adjust the pH of the system to 3.5, raise the temperature to 80 ℃, and react for 2 h at a stirring rate of 500 r / min. After the reaction is completed, filter while hot to obtain metatungstic acid leaching solution. The tungsten leaching rate is 99.5% (ICP-OES determination of W concentration is 28.3 g / L).
[0059] (3) Impurity removal and purification: A cation exchange resin (model 732) was added to the above leachate at a volume of 1 / 10 of the leachate (i.e., 25 mL resin / 250 mL solution). The mixture was reacted for 30 minutes at 35 ℃ and 200 r / min with stirring. The resin was then removed by filtration to obtain a pure metatungstic acid solution. ICP-MS analysis showed that the impurity ion Fe... 3+ The content was 3.2 ppm, Ca 2+ The content was 4.8 ppm, all of which were below 5 ppm.
[0060] Example 2
[0061] Synthesis of artificial tungsten ore by aqueous phase conversion and tungsten leaching purification
[0062] (1) Preparation of artificial tungsten ore: using solid tungstic acid (H2WO4) as the tungsten source, 20 g of tungstic acid powder and 15 g of barium hydroxide (Ba(OH)2·8H2O) were added to 500 mL of deionized water, heated to 90 ℃, and reacted for 4 h under stirring at 400 r / min. After the reaction was completed, the mixture was filtered, the filter cake was washed with hot water until pH≈7, and dried at 80 ℃ for 6 h to obtain white BaWO4 powder with a yield of 94.8%. XRD confirmed that it was a pure phase barite structure.
[0063] (2) Sulfuric acid leaching: Take 40 g of the above BaWO4 powder, add sulfuric acid solution, liquid-solid ratio 2:1, adjust pH to 0.5, heat to 90 ℃, stir reaction at 600 r / min for 3 h, filter to obtain metatungstic acid leaching solution, tungsten leaching rate is 99.3% (W concentration 106.8 g / L).
[0064] (3) Impurity removal and purification: A chelating resin (Lewatit TP 207, EDTA type) was selected and added to the leachate at a resin-to-leaching-solution mass ratio of 1:20 (approximately 16 g resin / 320 g solution). The mixture was stirred at 25 ℃ and 150 r / min for 45 minutes. After filtration, a pure metatungstic acid solution was obtained, containing Fe... 3+ Al 3+ Ba 2+ The total removal rate of impurity ions reached 99.8%, and the total impurity content in the final solution was < 6 ppm.
[0065] Example 3
[0066] Synthetic artificial tungsten ore by high-temperature roasting and tungsten leaching purification
[0067] (1) Preparation of artificial tungsten ore: Take 30 g of tungsten oxide (WO3) powder and 22 g of lead oxide (PbO) powder (molar ratio W:Pb = 1:1), grind and mix them thoroughly and place them in a corundum crucible. Calcine them at 800 ℃ for 4 h in an air atmosphere in a muffle furnace. After cooling naturally to room temperature, grind them through a 200-mesh sieve to obtain yellow PbWO4 powder with a yield of 99.1%. XRD shows that it has a pure phase scheelite structure.
[0068] (2) Hydrochloric acid leaching: Take 70 g of the above PbWO4 powder, add 175 mL of hydrochloric acid solution (concentration 0.5 mol / L, liquid-solid ratio 2:1), adjust pH to 1.5 (fine-tune with hydrochloric acid), heat to 70 ℃, stir at 300 r / min for 4 h, filter to remove insoluble residue (mainly unreacted PbCl2), and obtain metatungstic acid leaching solution with tungsten leaching rate of 99.7% (W concentration 124.5 g / L).
[0069] (3) Tungsten extraction: An amine extractant (trioctylamine, TOA) was dissolved in sulfonated kerosene (30% v / v) and added at a volume ratio of 1:5 between the extractant and the leachate. The mixture was reacted for 20 minutes at 50 °C and 250 r / min with stirring. Then, ammonia water was used for back-extraction to obtain a pure ammonium tungstate solution, which was then evaporated and crystallized to obtain APT. The APT was tested and found to meet the national grade 0 standard.
[0070] Example 4
[0071] Preparation of pure metatungstic acid solution by a combined hydrothermal synthesis-sulfuric acid leaching-solvent extraction method
[0072] (1) Preparation of artificial tungsten ore: Using industrial crude tungstic acid (H2WO4, WO3 content approximately 85%, containing impurities such as Fe, As, Si, and P) as the tungsten source, 47.0 g of crude tungstic acid powder (equivalent to 40.0 g of WO3, approximately 0.172 mol) and 13.0 g of calcium hydroxide (Ca(OH)2, Ca:W molar ratio = 1.05:1) were added to 350 mL of deionized water. After stirring evenly, the mixture was transferred to a 500 mL polytetrafluoroethylene-lined hydrothermal reactor, sealed, and heated to 110 ℃. The reaction was carried out at a constant temperature for 2 h. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered, and the filter cake was washed with deionized water until pH ≈ 7. The mixture was then dried at 90 ℃ for 5 h to obtain white CaWO4 artificial tungsten ore powder. XRD analysis showed that the structure was pure-phase scheelite, with impurity elements significantly enriched in the residue. The product contained Fe < 150 ppm and As < 30 ppm, with a yield of 96.1%.
[0073] (2) Sulfuric acid leaching: Take 50.0 g of the above-mentioned high-purity CaWO4 powder (containing approximately 42.5 g of WO3), add 210 mL of 2.5 mol / L sulfuric acid solution prepared with deionized water (liquid-to-solid ratio ≈ 4.2:1), adjust the pH of the system to 2.0, raise the temperature to 95 ℃, and react for 3 h at a stirring rate of 600 r / min. After the reaction is complete, filter while hot. The filter residue is slightly soluble CaSO4, and the filtrate is metatungstic acid leaching solution. ICP-OES determination shows that the WO3 concentration in the leaching solution is 202 g / L, the tungsten leaching rate reaches 98.2%, and the content of the main impurity ions in the solution is: Fe 3+ 85 ppm, Al 3+ 22 ppm, Ca 2+ 180 ppm, As 12 ppm, P8 ppm, Si 15 ppm.
[0074] (3) Impurity removal and purification: The above leachate was purified using a mixed extraction system. The organic phase of the extract consisted of 20% P2O4 + 50% TBP + 30% sulfonated kerosene. With a phase ratio of O / A = 1:1 (organic phase: aqueous phase = 1:1), 210 mL of leachate and 210 mL of organic phase were placed in a separatory funnel and extracted by shaking at 45 ℃ and 250 r / min for 10 minutes. After standing for 15 minutes to separate the layers, a pure metatungstic acid solution was obtained. ICP-MS analysis showed a significant reduction in impurity content in this solution: Fe 3+ < 2 ppm, Al 3+ < 1 ppm, Ca 2+ < 3 ppm, As < 0.5 ppm, P < 0.3 ppm, Si < 1 ppm, total impurities < 8 ppm, and WO3 concentration remains at 201 g / L (tungsten loss rate < 0.5%), meeting the requirements for the preparation of high-purity tungsten chemicals.
[0075] Application examples
[0076] Preparation of various tungsten compounds using pure metatungstic acid solution
[0077] The pure metatungstic acid solutions used in the following application examples were all prepared in Example 1 (concentration of 0.25 mol / L, approximately 30 g / L as WO3).
[0078] Application Example 1
[0079] Preparation of solid metatungstate and tungsten oxide
[0080] (1) Take 100 mL of pure metatungstic acid solution, place it in a vacuum drying oven, and dry it under reduced pressure at 60 °C for 6 h to obtain white fluffy solid metatungstic acid powder with a purity of 99.95% (GB / T 3459-2006).
[0081] (2) Take 10 g of the above solid metatungstate powder, place it in a muffle furnace, calcine at 600 °C for 2 h in an air atmosphere, and after natural cooling, obtain yellow hexagonal tungsten trioxide (WO3). XRD test (JCPDS No. 83-0950) shows that the crystal purity is good, there are no impurities, and the BET specific surface area is 8.3 m² / g.
[0082] Application Example 2
[0083] Preparation of phosphotungstic acid
[0084] Take 200 mL of pure metatungstic acid solution and add 2.8 mL of 85% phosphoric acid solution (concentration 14.7 mol / L, calculated based on a W:P molar ratio of 12:1). Heat to 80 °C and stir at 300 r / min for 2 h. After the reaction is complete, cool and crystallize in an ice-water bath for 4 h. Filter, wash with ethanol, and dry at 40 °C to obtain white phosphotungstic acid (H3PW). 12 O 40 The purity of the ·nH2O crystals was determined to be 99.94% by titration.
[0085] Application Example 3
[0086] Preparation of ammonium phosphotungstate
[0087] Take 200 mL of pure metatungstic acid solution, add ammonium phosphate solid ((NH4)3PO4, calculated according to W:P molar ratio of 12:1, i.e., add 4.1 g), heat to 60 ℃, stir at 250 r / min for 1.5 h, white crystals gradually precipitate during the reaction, continue to keep warm and stir for 30 minutes, filter, dry at 60 ℃ for 4 h to obtain ammonium phosphotungstic acid crystals with a purity of 99.96% (verified by ICP and P elemental analysis).
[0088] Application Example 4
[0089] Preparation of ammonium metatungstate
[0090] Take 300 mL of pure metatungstic acid solution, slowly add 25% ammonia water dropwise, adjust the pH of the system to 4.0 (monitored with a pH meter), raise the temperature to 70 ℃, stir the reaction at 200 r / min for 2 h, after the reaction is complete, treat with a spray dryer (inlet air temperature 180 ℃, outlet air temperature 80 ℃) to obtain white ammonium metatungstate ((NH4)2WO4 or polymerized state) crystals with a particle size D 50 = 15 μm, purity reaches 99.95%, meeting the national Class 0 product requirements.
[0091] Application Example 5
[0092] Preparation of ammonium paratungstate (APT)
[0093] Take 400 mL of pure metatungstic acid solution, add 25% ammonia water to adjust the pH to 6.0, heat to 80 ℃, stir at 300 r / min for 3 h. During the reaction, white needle-like crystals precipitate. After standing and cooling to room temperature, filter, wash the crystals 2–3 times with 5% ammonia water, and dry at 80 ℃ for 4 h to obtain ammonium paratungstate ((NH4)2). 10 W 12 O 41 It crystallizes with 5H2O, achieving a purity of 99.96%, meeting the national Class 0 product requirements.
[0094] Application Example 6
[0095] Preparation of tungstate
[0096] Take 200 mL of pure metatungstic acid solution, add 10 mL of 30% hydrogen peroxide solution (approximately 0.88 mol / L) and 20 mL of 1 mol / L sulfuric acid solution, stir well, and transfer to a 250 mL hydrothermal reactor. Heat to 150 ℃ and hydrothermally treat for 6 h. After cooling to room temperature, filter, wash with deionized water until pH=6, and dry at 60 ℃ to obtain white tungstic acid (H2WO4) solid with a purity of 99.96% (verified by TG-DSC and XRD).
[0097] Application Example 7
[0098] Hydrothermal preparation of tungsten oxide
[0099] Take 250 mL of pure metatungstic acid solution, add 15 mL of 30% hydrogen peroxide solution and 30 mL of 0.5 mol / L oxalic acid solution, mix well and transfer to a 300 mL hydrothermal reactor, hydrothermally treat at 180 ℃ for 4 h, cool and filter to obtain a pale yellow solid product, which was identified by XRD as tetragonal tungsten oxide (WO3·0.33H2O, JCPDS No. 89-4484) with a purity of 99.95%, and SEM showed that it had a nanosheet morphology.
[0100] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; however, any combination of these technical features that does not contradict each other should be considered within the scope of this specification.
Claims
1. A method for preparing tungsten compounds from synthetic tungsten ore, comprising: (1) Preparation of artificial tungsten ore: Prepare artificial tungsten ore, wherein the artificial tungsten ore is selected from any one or a mixture of CaWO4, Ca2WO5, Ca3WO6, PbWO4, and BaWO4; (2) Sulfuric acid leaching: The artificial tungsten ore is mixed with sulfuric acid and stirred for leaching reaction. The reaction conditions are controlled as follows: pH value 0.2~4.0, temperature 25~100℃, reaction time 30min~6h, liquid-solid ratio 1:1~10:1, stirring speed 100~600rpm. After the reaction is completed, metatungstic acid leaching solution is obtained. (3) Impurity removal and purification: Add a purifying agent to the metatungstic acid leachate and react for 1 to 60 minutes to remove impurity ions and obtain a pure metatungstic acid solution.
2. The method according to claim 1, wherein: The artificial tungsten ore in step (1) is synthesized using any of the following methods: ① Precipitation reaction method: A soluble salt, oxide, or hydroxide containing the target metal cation is added to an aqueous solution of tungstate, resulting in a precipitation reaction to form artificial tungsten ore; the tungstate is selected from any one of sodium tungstate, ammonium tungstate, and potassium tungstate; the target metal cation is Ca. 2+ Pb 2+ Ba 2+ Any one or more of the following; ② Aqueous phase transformation method: using solid tungstic acid or tungsten oxide as the tungsten source, it is mixed with a slightly soluble or sparingly soluble compound of the target metal in an aqueous medium, and reacted under heating or stirring conditions to transform into artificial tungsten ore; the target metal is any one or more of Ca, Pb, and Ba; the slightly soluble or sparingly soluble compound is selected from any one of the hydroxides, oxides, carbonates, and basic carbonates of the target metal; ③ High-temperature roasting method: Tungsten source is mixed with oxides or salts of the target metal and roasted at high temperature to synthesize artificial tungsten ore; the tungsten source is selected from any one or more of tungsten oxide, tungstic acid, scheelite, and wolframite; the target metal is any one or more of Ca, Pb, and Ba; ④ Special process synthesis method: Synthetic artificial tungsten ore is synthesized by sol-gel process or hydrothermal reactor reaction.
3. The method according to claim 1, wherein: The purifying agent in step (3) is selected from any one of cation exchange resin, chelating resin, and organophosphorus extractant.
4. The method according to claim 1, wherein: The impurity ions in step (3) include: Fe 3+ Al 3+ Ca 2+ Pb 2+ Ba 2+ One or more of phosphorus, arsenic, and silicon; The metatungstic acid leachate was purified to obtain a pure metatungstic acid solution.
5. A pure metatungstic acid solution prepared according to any one of claims 1 to 4.
6. The application of the pure metatungstic acid solution according to claim 5 in the preparation of solid metatungstic acid, phosphotungstic acid, ammonium phosphotungstate, tungsten oxide, ammonium metatungstate, ammonium paratungstate, and tungstic acid.
7. The application according to claim 6, wherein: The preparation of solid metatungstic acid includes the following method: drying a pure metatungstic acid solution at 30~90℃ to obtain solid metatungstic acid; The preparation of phosphotungstic acid includes the following method: adding phosphoric acid to a pure metatungstic acid solution, controlling the molar ratio of W to P to be 12:1, stirring the reaction at 20~100℃ for 10 min~4 hours, concentrating and crystallizing to obtain phosphotungstic acid; The preparation of ammonium phosphotungstate includes the following method: adding ammonium phosphate to a pure metatungstic acid solution, controlling the molar ratio of W to P to be 12:1, stirring and reacting at 20~100℃ for 10 min~4 hours, and directly precipitating ammonium phosphotungstate crystals; The preparation of ammonium metatungstate includes the following method: adding ammonia water to a pure metatungstate solution, adjusting the pH of the solution to 3-5, stirring the reaction at 20-100℃ for 10 min-4 hours, and spray drying to obtain ammonium metatungstate crystals; The preparation of ammonium paratungstate includes the following method: adding ammonia water to a pure metatungstic acid solution, adjusting the pH of the solution to 5-7, stirring the reaction at 20-100℃ for 10 min-4 hours, and directly precipitating ammonium paratungstate crystals; The preparation of tungstic acid or tungsten oxide includes the following method: adding 0~1 mol / L hydrogen peroxide and 0~2 mol / L acid to a pure metatungstic acid solution, wherein the acid is selected from any one of sulfuric acid, hydrochloric acid, nitric acid, and oxalic acid; and then hydrothermally treating at 100~200℃ for 0.5~24 hours to obtain tungstic acid or tungsten oxide.
8. A metatungstate leaching solution prepared by the method according to any one of claims 1 to 6.
9. An application of the metatungstate leaching solution according to claim 8 in the preparation of tungsten compounds, comprising: Tungsten compounds are prepared by extracting tungsten from metatungstic acid leachate using ion exchange or dissolution extraction, wherein: The ion exchange resin is a macroporous weakly basic anion exchange resin. The extractant is selected from amine extractants or neutral phosphorus extractants.