A method for decomposing wolframite by sulfuric acid enhancement

Abstract

The present invention belongs to the field of hydrometallurgy technology, and specifically relates to a method for strengthening the decomposition of wolframite with sulfuric acid, comprising the steps of: S1, grinding the wolframite, adding a decomposition aid, mixing with sulfuric acid, and heating and low-temperature roasting; S2, mixing the roasted material with water, stirring and leaching, and filtering to obtain a filter residue; S3, washing the filter residue with water and then dissolving it with ammonia to obtain an ammonium tungstate solution. The present invention uses a single sulfuric acid, and strengthens the decomposition through low-temperature roasting, thereby enhancing the decomposition efficiency. Compared with conventional acid decomposition, the tungsten conversion rate is greater than 99%, and the tungsten leaching rate is greater than 98%; the added cerium-based decomposition aid does not generate gas, is not flammable and explosive, and completely enters the solution after water immersion, and has no effect on the quality of subsequent products; the leaching process of the present invention is carried out at normal pressure, without the need for high pressure, and the operation process is safe and reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for decomposing wolframite by enhanced sulfuric acid. Background Art

[0002] The classic method for processing wolframite in the industry at present is high temperature and high pressure sodium hydroxide pressure cooking to obtain crude sodium tungstate and alkali cooking residue, and the crude sodium tungstate solution is transformed into ammonium tungstate solution by ion exchange or solvent extraction. However, this method has the following problems: first, the alkali used is expensive, resulting in high alkali decomposition costs; second, a large amount of alkali cooking residue is produced, which is solid hazardous waste and needs to be outsourced to qualified enterprises for treatment, which greatly increases the treatment cost; third, a large amount of sodium hydroxide is added, and sodium salt is added outside the system, which produces a large amount of high-salt wastewater, and the cost of wastewater treatment is high.

[0003] In order to reduce the decomposition cost of wolframite and achieve the reduction of slag, the acid treatment technology is a more reasonable process. Patent 201610341064.7 discloses a method of using sulfuric acid to decompose black and white tungsten mixed ore, adding wolframite to a certain concentration of sulfuric acid solution for transformation reaction, obtaining transformation filtrate and transformation material, adding a certain concentration of ammonium salt or sodium salt solution to the transformation material, obtaining ammonium tungstate solution or sodium tungstate solution, and achieving most of the decomposition of black and white tungsten ore; Patent 201810360985.7 discloses a method for preparing tungsten products by acid decomposition of black and white tungsten mixed ore, through leaching-filtration washing-hydrogen peroxide extraction-decomposition and extraction of tungsten, thereby obtaining relatively pure tungstic acid, the decomposition slag produced by this process is gypsum, which does not belong to hazardous waste, but this process uses a large amount of hydrogen peroxide, and the production cost is relatively high. Patent 201810331171.0 discloses a method for extracting tungsten by decomposing wolframite or black wolframite under pressure with sulfur-phosphorus mixed acid. A mixed acid of phosphoric acid and sulfuric acid is used as the reaction medium, and the reaction system is pressurized to make the reaction temperature 110-250°C. The extraction process does not require the addition of calcium-containing compounds to transform the wolframite, which simplifies the production process. However, the invention uses high-pressure processing technology, which places higher requirements on the reaction equipment and operation.

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing ammonium tungstate solution by acid decomposing wolframite. The preparation method is simple, has a short process flow, uses less reagents, and reduces the generation of high-salt wastewater. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a method for decomposing wolframite by enhanced sulfuric acid.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A method for decomposing wolframite by sulfuric acid enhancement comprises the following steps:

[0008] S1, grinding wolframite, adding decomposition aid, mixing with sulfuric acid, heating and low-temperature roasting;

[0009] S2, mixing the roasted material with water, stirring and leaching, and filtering to obtain a filter residue;

[0010] S3, washing the filter residue with water and then dissolving it with ammonia to obtain an ammonium tungstate solution;

[0011] The decomposition aid is one of CeO2 and Ce(SO4)2 or a mixture of the two in any proportion, and the mass used is 0.1% to 5% of the mass of wolframite.

[0012] The present invention generates complex cerium-tungsten compounds by adding a cerium-based decomposition aid to react with wolframite, collectively known as cerium tungstate (Ce2W3O 12 ), cerium tungstate decomposes into cerium sulfate and tungstic acid in high temperature and concentrated sulfuric acid, thereby realizing efficient conversion of wolframite. The decomposition aid not only forms new compounds with tungsten, but also oxidizes Fe(II) to Fe(III), destroying the crystal phase structure of wolframite, further improving the decomposition rate of tungsten ore, and realizing enhanced decomposition of wolframite under normal pressure and single sulfuric acid system. The tungsten conversion rate is greater than 99%, and the tungsten leaching rate is greater than 98%.

[0013] The reactions involved are as follows:

[0014] FeWO4+ Ce(IV)→ Ce2W3O 12 + Fe(III)

[0015] Ce2W3O 12 + H2SO4→ Ce(III)+ H2WO4+ SO3

[0016] As a preferred embodiment of the method for decomposing wolframite with sulfuric acid, the content of tungsten trioxide in the wolframite is 1wt% to 80wt%, and the particle size of the wolframite is 10 mesh to 400 mesh. More preferably, the content of tungsten trioxide in the wolframite is 40wt% to 70wt%, and the particle size of the wolframite is 100 mesh to 300 mesh.

[0017] As a preferred embodiment of the method for decomposing wolframite with enhanced sulfuric acid according to the present invention, the decomposition aid is CeO2, and the mass used is 0.5% to 1% of the mass of the wolframite.

[0018] As a preferred embodiment of the method for decomposing wolframite with enhanced sulfuric acid according to the present invention, in step S1, the mass concentration of sulfuric acid is 80% to 96%, and the weight ratio of sulfuric acid to wolframite is 20% to 200%. More preferably, the mass concentration of sulfuric acid is 90% to 96%, and the weight ratio of sulfuric acid to wolframite is 100% to 150%.

[0019] As a preferred embodiment of the method for decomposing wolframite with sulfuric acid intensified according to the present invention, in step S1, the roasting temperature is 150°C to 280°C, and the roasting time is 30 to 300 minutes. More preferably, the roasting temperature is 200°C to 250°C, and the roasting time is 60 to 120 minutes.

[0020] As a preferred embodiment of the method for decomposing wolframite with enhanced sulfuric acid according to the present invention, in step S2, the mass of water used is 1 to 10 times the mass of wolframite, the leaching temperature is from room temperature to 100°C, and the leaching time is 30 to 300 minutes. More preferably, the mass used is 3 to 6 times the mass of wolframite, the leaching temperature is 50°C to 80°C, and the leaching time is 60 minutes to 120 minutes.

[0021] As a preferred embodiment of the method for decomposing wolframite with enhanced sulfuric acid according to the present invention, in step S3, the water washing is performed by countercurrent washing until the acid content in the filter residue is less than 0.1 mol / L.

[0022] As a preferred embodiment of the method for decomposing wolframite with enhanced sulfuric acid according to the present invention, the washing liquid after washing is returned to step S2 to be mixed with water and leached.

[0023] As a preferred embodiment of the method for decomposing wolframite with enhanced sulfuric acid according to the present invention, in step S3, when performing ammonia dissolution, the ratio of the amount of ammonia used to the amount of tungsten trioxide in the filter residue is 2 to 20:1, the ammonia dissolution time is 30 min to 300 min, the temperature is room temperature to 70°C, and the solid-liquid ratio is 1:1 to 1:10. More preferably, the ratio of the amount of ammonia used to the amount of tungsten trioxide in the filter residue is 2 to 5:1, the ammonia dissolution time is 30 min to 60 min, the temperature is 50 to 70°C, and the solid-liquid ratio is 1:2 to 1:6.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The present invention adopts auxiliary decomposition aids and sulfuric acid low-temperature roasting to strengthen decomposition, thereby enhancing the decomposition efficiency. Compared with the decomposition of the conventional acid system, the tungsten conversion rate is greater than 99%, and the tungsten leaching rate is greater than 98%. Compared with alkaline pressure cooking, it saves a lot of energy, reduces the generation of high-salt wastewater, and thus saves wastewater treatment costs.

[0026] 2. The cerium-based decomposition aid added in the present invention does not generate gas, is not flammable or explosive, and completely enters the solution after being immersed in water, without affecting the quality of subsequent products.

[0027] 3. The present invention adopts a single sulfuric acid system for treatment, and does not require other acids for treatment. It replaces high-valent alkali and volatile acid, saves treatment costs, and reduces equipment corrosion. The leaching process of the present invention is carried out at normal pressure, does not require high pressure, and the operation process is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0029] Figure 1 It is a process flow chart of the present invention.

[0030] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0031] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1 According to one aspect of the present invention, the present invention provides the following technical solution:

[0033] A method for decomposing wolframite by sulfuric acid enhancement comprises the following steps:

[0034] S1, grinding wolframite, adding decomposition aid, mixing with sulfuric acid, heating and low-temperature roasting;

[0035] S2, mixing the roasted material with water, stirring and leaching, and filtering to obtain a filter residue;

[0036] S3, washing the filter residue with water and then dissolving it with ammonia to obtain an ammonium tungstate solution;

[0037] The decomposition aid is one of CeO2 and Ce(SO4)2 or a mixture of the two in any proportion, and the mass used is 0.1% to 5% of the mass of the ore.

[0038] The present invention uses a single sulfuric acid system, adds a cerium-based decomposition aid, strengthens decomposition through low-temperature roasting, and enhances decomposition efficiency. Compared with conventional multi-system acid decomposition, the tungsten conversion rate is greater than 99%, and the tungsten leaching rate after ammonia dissolution is greater than 98%, thereby realizing efficient conversion of wolframite. The added cerium-based decomposition aid does not generate gas, is not flammable or explosive, and completely enters the solution after water immersion, without affecting the quality of subsequent products. The present invention has a high reaction rate, and the leaching process is carried out at normal pressure, so that efficient conversion of wolframite can be realized without high pressure, and the equipment cost is low, and the operation process is safe and reliable.

[0039] Preferably, the content of tungsten trioxide in wolframite is 1wt%~80wt%, and the particle size of wolframite is 10 mesh~400 mesh. More preferably, the content of tungsten trioxide in wolframite is 40wt%~70wt%, and the particle size of wolframite is 100 mesh~300 mesh.

[0040] Preferably, in step S1, the decomposition aid is CeO2, and the mass used is 0.5% to 1% of the mass of wolframite.

[0041] Preferably, in step S1, the mass concentration of sulfuric acid is 80% to 96%, and the weight ratio of sulfuric acid to wolframite is 20% to 200%. More preferably, the mass concentration of sulfuric acid is 90% to 96%, and the weight ratio of sulfuric acid to wolframite is 100% to 150%.

[0042] Preferably, in step S1, the calcination temperature is 150°C to 280°C, and the calcination time is 30 to 300 min. More preferably, the calcination temperature is 200°C to 250°C, and the calcination time is 60 min to 120 min.

[0043] Preferably, in step S2, the mass of water used is 1 to 10 times the mass of wolframite, the leaching temperature is room temperature to 100°C, and the leaching time is 30 min to 300 min. More preferably, the mass of water used is 3 to 6 times the mass of wolframite, the leaching temperature is 50°C to 80°C, and the leaching time is 60 min to 120 min.

[0044] Preferably, in step S3, the water washing is performed by countercurrent washing until the acid content in the filter residue is less than 0.1 mol / L.

[0045] Preferably, the washing liquid after washing is returned to step S2 to be mixed with water and leached. The washing liquid contains acid, which can be further utilized in the leaching process, thereby reducing the processing cost.

[0046] Preferably, in step S3, when performing ammonia dissolution, the ratio of ammonia to tungsten trioxide in the filter residue is 2 to 20:1, the ammonia dissolution time is 30 to 300 minutes, the temperature is room temperature to 70°C, and the solid-liquid ratio is 1:1 to 1:10. More preferably, the ratio of ammonia to tungsten trioxide in the filter residue is 2 to 5:1, the ammonia dissolution time is 30 minutes to 60 minutes, the temperature is 50°C to 70°C, and the solid-liquid ratio is 1:2 to 1:6.

[0047] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0048] Example 1

[0049] The specific operation process in this embodiment is as follows:

[0050] Take 1000g of wolframite (WO3%=65wt%) and grind it to obtain 300-mesh wolframite, add 10g of CeO2 solid, mix it, and then add 1000g of industrial sulfuric acid (mass concentration is 96%), stir it evenly, put it into a muffle furnace and roast it for 2h (temperature is 200℃), take it out while hot, rinse it with 4000mL of water and transfer it to the reactor, heat it to 80℃ and stir it for 2h, filter it, and obtain 3460mL of leachate and 920g of wet leachate residue; add 4000mL of water to the leachate residue for washing, the washing temperature is room temperature, the washing time is 30min, and 3970mL of primary washing liquid is obtained after filtering. With 890g of primary washing slag, the obtained primary washing can be used for the leaching water of the next batch of roasted ore; add 4000mL of water to the primary washing slag for secondary washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 3950mL of secondary washing liquid and 880g of secondary washing slag are obtained, and the obtained secondary washing liquid can be used for the next batch of primary washing water; add 4000mL of water to the secondary washing slag for washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 3960mL of tertiary washing liquid and 850g of tertiary washing slag are obtained, and the obtained tertiary washing liquid can be used for the next batch of secondary washing water. Add 3000mL of 6mol / L ammonia water to the tertiary washing slag, stir at room temperature for 60min, dissolve in ammonia, and after filtering, 2890mL of ammonium tungstate solution and 265g of ammonia slag are obtained.

[0051] In this embodiment, it was determined that the leaching rate of tungsten was 98.34%.

[0052] Example 2

[0053] The specific operation process in this embodiment is as follows:

[0054] Take 1000g of wolframite (WO3%=1wt%) and grind it to get 30 mesh wolframite, add 10g of Ce(SO4)2 solid, add 2000g of industrial sulfuric acid (mass concentration is 80%) after mixing, stir evenly and put it into a muffle furnace for roasting for 30h (temperature is 280℃), take it out while hot, rinse it with 10000mL of water and transfer it to the reactor, stir it at room temperature for 2h, filter it, and get 9320mL of leaching liquid and 436g of wet leaching residue; add 1000mL of water to the leaching residue for washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 970mL of primary washing liquid and 421g of primary washing residue are obtained. The obtained primary washing can be Used as leaching water for the next batch of roasted ore; add 1000mL of water to the first washing slag for secondary washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 950mL of secondary washing liquid and 415g of secondary washing slag are obtained, and the obtained secondary washing liquid can be used for the next batch of primary washing water; add 1000mL of water to the secondary washing slag for washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 960mL of tertiary washing liquid and 418g of tertiary washing slag are obtained, and the obtained tertiary washing liquid can be used for the next batch of secondary washing water. Add 1000mL of 6mol / L ammonia water to the tertiary washing slag, stir at room temperature for 60min, dissolve in ammonia, and after filtering, 290mL of ammonium tungstate solution and 380g of ammonia-dissolved slag are obtained.

[0055] In this embodiment, it was determined that the leaching rate of tungsten was 99.01%.

[0056] Example 3

[0057] The specific operation process in this embodiment is as follows:

[0058] Take 1000g of wolframite (WO3%=80wt%) and grind it to obtain 300-mesh wolframite, add 50g of CeO2 solid, mix it, and then add 2000g of industrial sulfuric acid (mass concentration is 96%), stir it evenly, put it into a muffle furnace and roast it for 2h (temperature is 250℃), take it out while hot, rinse it with 4000mL of water and transfer it to the reactor, heat it to 80℃ and stir it for 2h, filter it, and obtain 3250mL of leachate and 980g of wet leachate residue; add 4000mL of water to the leachate residue for washing, the washing temperature is room temperature, the washing time is 30min, and 3890mL of primary washing liquid is obtained after filtering. With 934g of primary washing slag, the primary washing can be used for the next batch of leaching water for roasted ore; add 4000mL of water to the primary washing slag for secondary washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 3930mL of secondary washing liquid and 921g of secondary washing slag are obtained, and the secondary washing liquid can be used for the next batch of primary washing water; add 4000mL of water to the secondary washing slag for washing, the washing temperature is room temperature, the washing time is 30min, and after filtering, 3940mL of tertiary washing liquid and 920g of tertiary washing slag are obtained, and the tertiary washing liquid can be used for the next batch of secondary washing water. Add 5000mL of 6mol / L ammonia water to the tertiary washing slag, stir at room temperature for 300min, dissolve in ammonia, and after filtering, 4820mL of ammonium tungstate solution and 162g of ammonia slag are obtained.

[0059] In this embodiment, it was determined that the leaching rate of tungsten was 98.11%.

[0060] Comparative Example 1

[0061] The other operations were the same as those in Example 1, except that no cerium oxide decomposition aid was added. The tungsten leaching rate was measured to be 94.62%, which was 3.72% less than that when the aid was added.

[0062] From the above comparison, it can be seen that the addition of decomposition aids can effectively improve the conversion of tungsten in tungsten ore, thereby improving the leaching efficiency of tungsten. This is because the method generates cerium tungstate (Ce2W3O 12 ), cerium tungstate decomposes into cerium sulfate and tungstic acid in high temperature and concentrated sulfuric acid, thereby realizing the efficient conversion of wolframite. The decomposition aid not only forms new compounds with tungsten, but also oxidizes Fe(II) to Fe(III), destroying the crystal phase structure of wolframite and further improving the decomposition rate of tungsten ore.

[0063] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for decomposing wolframite by sulfuric acid enhancement, characterized in that: The steps include: S1, grind wolframite, add decomposition aid, mix with sulfuric acid, heat and roast at low temperature; S2, mixing the roasted material with water, stirring and leaching, and filtering to obtain a filter residue; S3, washing the filter residue with water and then dissolving it with ammonia to obtain an ammonium tungstate solution; The decomposition aid is one of CeO2 and Ce(SO4)2 or a mixture of the two in any proportion, and the mass used is 0.1% to 5% of the mass of wolframite.

2. The method for decomposing wolframite with sulfuric acid according to claim 1, characterized in that: The content of tungsten trioxide in wolframite is 1wt%~80wt%, and the particle size of wolframite is 10 mesh~400 mesh.

3. The method for decomposing wolframite by sulfuric acid enhancement according to claim 1, characterized in that: The decomposition aid is CeO2, and the mass used is 0.5% to 1% of the mass of wolframite.

4. The method for decomposing wolframite with sulfuric acid according to claim 1, characterized in that: In the step S1, the mass concentration of sulfuric acid is 80% to 96%, and the weight ratio of sulfuric acid to wolframite is 20% to 200%.

5. The method for decomposing wolframite with sulfuric acid according to claim 1, characterized in that: In the step S1, the calcination temperature is 150° C. to 280° C., and the calcination time is 30 min to 300 min.

6. The method for decomposing wolframite by enhanced sulfuric acid according to any one of claims 1 to 5, characterized in that: In step S2, the mass of water used is 1 to 10 times the mass of wolframite, the leaching temperature is room temperature to 100° C., and the leaching time is 30 min to 300 min.

7. The method for decomposing wolframite by enhanced sulfuric acid according to any one of claims 1 to 5, characterized in that: In step S3, the water washing is performed by countercurrent washing until the acid content in the filter residue is less than 0.1 mol / L.

8. The method for decomposing wolframite with sulfuric acid according to claim 7, characterized in that: The washing liquid after washing is returned to step S2 to be mixed with water and leached.

9. The method for decomposing wolframite with sulfuric acid according to claim 1, characterized in that: In step S3, when ammonia dissolution is performed, the ratio of ammonia to tungsten trioxide in the filter residue is 2-20:1, the ammonia dissolution time is 30-300 minutes, the temperature is room temperature to 70°C, and the solid-liquid ratio is 1:1-1:10.

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