Method for removing fluorine from high-fluorine tungsten ore

Abstract

The invention discloses a method for removing fluorine from high-fluorine tungsten ore, which comprises the following steps of: S1, carrying out ball milling on the high-fluorine tungsten ore to enable the granularity of ore pulp to be less than 325 meshes, and enabling the obtained ore pulp to enter the next procedure; on one hand, fluorine is removed from the source, the fluorine is concentrated and enriched from the source, the fluorine is removed by adding the fluorine removal agent, the fluorine element is prevented from entering the main process to pollute the production process and the product, and compared with the fluorine removal in the production wastewater, the fluorine removal difficulty and the wastewater fluorine removal treatment cost are reduced; on the other hand, excessive sodium hydroxide after the soda boiling decomposition process is concentrated, enriched and recycled, and the defluorinated sodium hydroxide mother liquor is returned to the main process for pulp mixing and soda boiling for use, so that the use amount of new alkali in the soda decomposition process is greatly reduced, the production cost is saved, and the economic benefits of enterprises are increased; the method is simple to operate, cheap in raw materials, low in energy consumption and easy to industrialize.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for removing fluorine from high-fluorine tungsten ore. Background Art

[0002] China is a country with abundant tungsten resources, and its total tungsten reserves account for more than 50% of the world's total reserves. With the continuous development and utilization of tungsten resources, the black tungsten resources that are easy to smelt are gradually exhausted, and the raw materials for tungsten smelting have transitioned to low-grade black and white tungsten or scheelite. Most black and white tungsten ores or scheelite have poor resource endowments, and the co-existence relationship is very complex. They are often accompanied by impurities such as molybdenum, phosphorus, arsenic, silicon, and fluorine, and the embedded particles are fine and the grade is low (more than 80% of the grade is less than 0.4%). In particular, the fluorine content in tungsten raw materials has become higher and higher in recent years. The existing tungsten smelting process treats such low-grade and complex high-fluorine tungsten minerals. The main production processes are alkaline decomposition ion exchange, sodium carbonate decomposition acid extraction, sodium carbonate decomposition alkaline extraction and other production processes. The production wastewater produced by the above production processes contains a large amount of fluorine. In order to ensure that the production wastewater meets the discharge standards, the production wastewater needs to be defluorinated, which increases the production cost. Therefore, how to effectively remove impurities in low-grade complex black and white tungsten mixed ores, thereby efficiently extracting tungsten resources, is conducive to the high-quality and sustainable development of the tungsten industry.

[0003] In order to solve the problem that the fluorine element in high-fluorine tungsten ore enters the solution during the production process and finally enters the production wastewater. In order to ensure that the production wastewater meets the discharge standards, how to remove fluorine from the source, reduce the cost of removing fluorine from production wastewater, and at the same time eliminate the impact of fluorine on the production process, reduce the corrosion of fluorine-containing liquid on equipment in the production process, and further prevent the fluorine element from entering the product and affecting the product quality. The present invention provides a method for removing fluorine from high-fluorine tungsten ore. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a method for removing fluorine from high-fluorine tungsten ore, which effectively solves the problems raised by the background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for removing fluorine from high-fluorine tungsten ore, comprising the following steps:

[0006] Step S1: ball milling the high-fluorine tungsten ore to make its slurry particle size less than 325 mesh, and the obtained slurry enters the next process;

[0007] Step S2: adding sodium hydroxide to the high-fluorine tungsten slurry ball-milled in step S1 to adjust the slurry to a liquid-solid ratio of 1.2:1-4:1, and adding the adjusted slurry to a reactor for heating reaction, the reaction temperature is controlled at 140-180°C, and the reaction is carried out for 3-4 hours;

[0008] Step S3: Put the slurry reacted in step S2 into a dilution tank with water added, dilute the volume to 2-6 times the volume of the slurry and filter, concentrate the filtered concentrated solution through an evaporator, and when the sodium hydroxide concentration in the solution is greater than 300g / L, cool and filter the solution to obtain sodium tungstate crystals and high-fluorine sodium hydroxide mother liquor, the sodium tungstate crystals are dissolved in water to obtain a sodium tungstate solution that enters the main process for preparing ammonium paratungstate products, and the obtained high-fluorine sodium hydroxide mother liquor enters the next process;

[0009] Step S4: adding a defluorinating agent to the high-fluorine sodium hydroxide mother liquor, heating and stirring the reaction for 1-2 hours, and then filtering to obtain a filter residue and a low-fluorine sodium tungstate solution, and the low-fluorine sodium hydroxide solution is returned to the slurry adjustment and alkali boiling process.

[0010] Preferably, the high-fluorine tungsten ore in step S1 contains 10.0-65.0% WO3 and 0.5-15.0% F;

[0011] Tungsten ore particle size <325 mesh is greater than 95.0%.

[0012] Preferably, sodium hydroxide is added in step S2 for slurry adjustment, and the amount of sodium hydroxide used is 1.5-4 times the theoretical amount.

[0013] Preferably, in step S2, the ore pulp is added into a reactor and heated for reaction at a temperature of 140-180° C. for 1-5 hours.

[0014] Preferably, in step S3, the solution is concentrated by an evaporator, and the concentration of sodium hydroxide in the solution is 300-500 g / L.

[0015] Preferably, the defluorination agent in step S4 is carbonate and calcium salt, the amount of carbonate added is 0.1%-0.5% of the solution mass, and the amount of calcium salt added is 1.5-3.0 times the theoretical amount of fluorine content in the solution;

[0016] The carbonate is sodium carbonate and the calcium salt is calcium oxide.

[0017] Preferably, in step S4, the heating and stirring are performed at a temperature of 60-90°C.

[0018] Preferably, in step S2, the heating method in the reactor is one of electric heating, steam heating, far infrared heating or thermal oil heating.

[0019] Preferably, in step S3, the evaporator performs concentration, the evaporator is heated by steam or by thermal oil, and the evaporator is single-effect, double-effect, triple-effect or multi-effect.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. On the one hand, the present invention removes fluorine from the source, concentrates and enriches fluorine at the source, and adds a defluorinating agent to remove fluorine, thereby preventing fluorine from entering the main process and polluting the production process and products. Compared with removing fluorine from production wastewater, the difficulty of removing fluorine and the cost of wastewater defluorination treatment are reduced; on the other hand, the excess sodium hydroxide after the alkali boiling and decomposition process is recovered by concentration and enrichment, and the sodium hydroxide mother liquor after defluorination is returned to the main process for slurry mixing and alkali boiling, which greatly reduces the amount of new alkali in the alkali decomposition process, saves production costs, and increases the economic benefits of the enterprise; the method of the present invention is simple to operate, has cheap raw materials, low energy consumption, and is easy to industrialize;

[0022] 2. In the method of step S2 of the present invention, sodium hydroxide is added to the ore pulp for slurry adjustment. The sodium hydroxide used for slurry adjustment is the low-fluorine sodium hydroxide solution concentrated and recovered in step S3. The sodium hydroxide is recovered by alkali concentration, which greatly reduces the amount of auxiliary solid sodium hydroxide, reduces the amount of environmentally friendly neutralization and acid addition, reduces the salt content in production wastewater, and increases economic benefits;

[0023] 3. In step S3 of the method of the present invention, the solution is cooled and solid-liquid separated to obtain sodium tungstate crystals. The sodium tungstate crystals are dissolved to generate a sodium tungstate solution with a very low impurity content. The low-alkali and low-impurity sodium tungstate solution enters the main process for ion exchange, which increases the ion exchange adsorption capacity and the desorption ammonium tungstate concentration, and correspondingly reduces the consumption of various auxiliary materials for ion exchange and the power consumption of the evaporation crystallization process, thereby increasing the economic benefits;

[0024] 4. In step S3 of the method of the present invention, the solution is cooled and solid-liquid separated to obtain sodium tungstate crystals. The sodium tungstate crystals are dissolved to generate sodium tungstate solution which enters the main process for ion exchange and tungsten absorption. The high-purity ammonium tungstate solution obtained by the analysis is evaporated and crystallized to prepare a high-purity ammonium paratungstate product, thereby improving the quality of the ammonium paratungstate product.

[0025] 5. In step S3 of the method of the present invention, the solution is cooled and solid-liquid separated to obtain sodium tungstate crystals and sodium hydroxide mother liquor. The sodium tungstate crystal solution generates a sodium tungstate solution with an alkali concentration of less than 2 g / L. The wastewater generated after ion exchange treatment contains less than 0.005 g / L of fluorine, which reduces the amount of acid used for neutralizing alkali in environmental protection treatment, reduces the amount of auxiliary materials such as defluorinating agents, and reduces the amount of salt entering the water, thereby reducing the cost of environmental protection sewage treatment and increasing the economic benefits of the enterprise.

[0026] 6. The auxiliary materials of the present invention are common calcium salts, carbonates and sodium hydroxide, etc., which are low in cost, high in reliability and suitable for large-scale production;

[0027] 7. The method for removing fluorine from high-fluorine tungsten ore of the present invention achieves zero emission during the fluorine removal process;

[0028] 8. Compared with the environmentally friendly sewage treatment which needs to consume a large amount of alkali to adjust the pH of the sewage before defluorination, the method for defluorination of high-fluorine tungsten ore described in the present invention makes full use of the solution in strong alkaline defluorination, uses less reagents, and removes fluoride at the source, achieving the advantages of obvious defluorination effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0030] In the attached picture:

[0031] Figure 1 This is a schematic flow diagram of a method for removing fluorine from high-fluorine tungsten ore according to the present invention; DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Depend on Figure 1 The present invention relates to a method for removing fluorine from high-fluorine tungsten ore, comprising the following steps:

[0034] Step S1: ball milling the high-fluorine tungsten ore to make its slurry particle size less than 325 mesh, and the obtained slurry enters the next process;

[0035] Step S2: adding sodium hydroxide to the high-fluorine tungsten slurry ball-milled in step S1 to adjust the slurry to a liquid-solid ratio of 1.2:1-4:1, and adding the adjusted slurry to a reactor for heating reaction, the reaction temperature is controlled at 140-180°C, and the reaction is carried out for 3-4 hours;

[0036] Step S3: Put the slurry reacted in step S2 into a dilution tank with water added, dilute the volume to 2-6 times the volume of the slurry and filter, concentrate the filtered concentrated solution through an evaporator, and when the sodium hydroxide concentration in the solution is greater than 300g / L, cool and filter the solution to obtain sodium tungstate crystals and high-fluorine sodium hydroxide mother liquor, the sodium tungstate crystals are dissolved in water to obtain a sodium tungstate solution that enters the main process for preparing ammonium paratungstate products, and the obtained high-fluorine sodium hydroxide mother liquor enters the next process;

[0037] Step S4: adding a defluorinating agent to the high-fluorine sodium hydroxide mother liquor, heating and stirring the reaction for 1-2 hours, and then filtering to obtain a filter residue and a low-fluorine sodium tungstate solution, and the low-fluorine sodium hydroxide solution is returned to the slurry adjustment and alkali boiling process.

[0038] In step S1 of this embodiment, the high-fluorine tungsten ore contains 10.0-65.0% WO3 and 0.5-15.0% F;

[0039] Tungsten ore particle size <325 mesh is greater than 95.0%.

[0040] In step S2 of this embodiment, sodium hydroxide is added to adjust the slurry, and the amount of sodium hydroxide used is 1.5-4 times the theoretical amount.

[0041] In step S2 of this embodiment, the slurry is added into the reactor and heated for reaction at a temperature of 140-180° C. for 1-5 hours.

[0042] In step S3 of this embodiment, the solution is concentrated by an evaporator, and the concentration of sodium hydroxide in the solution is 300-500 g / L.

[0043] In step S4 of this embodiment, the defluorination agent is carbonate and calcium salt, the amount of carbonate added is 0.1%-0.5% of the solution mass, and the amount of calcium salt added is 1.5-3.0 times the theoretical amount of fluorine content in the solution;

[0044] The carbonate is sodium carbonate and the calcium salt is calcium oxide.

[0045] In step S4 of this embodiment, heating and stirring are performed at a temperature of 60-90°C.

[0046] In step S2 of this embodiment, the heating method in the reactor is one of electric heating, steam heating, far infrared heating or thermal oil heating.

[0047] In step S3 of this embodiment, the evaporator performs concentration, and the evaporator adopts one of steam heating and thermal oil heating, and the evaporator adopts one of single effect, double effect, triple effect or multiple effect.

[0048] Embodiment 1:

[0049] The high-fluorine tungsten ore containing 56.2% WO3 and 5.2% F was ball-milled to make its slurry particle size less than 325 mesh and greater than 95%. Sodium hydroxide was added to the obtained slurry to adjust the liquid-solid ratio to 1.3:1, and the adjusted slurry was added to the reactor for heating reaction. The reaction temperature was controlled at 140-180℃ and the reaction was carried out for 3.5 hours. The slurry with good reaction was placed in a dilution tank with water added. The dilution volume was 3 times the slurry volume and filtered. The filtered concentrated solution was concentrated by an evaporator. When the sodium hydroxide concentration in the concentrated solution reached 360g / L, the concentrated solution was cooled and filtered to obtain sodium tungstate crystals and 5m sodium hydroxide mother liquor containing 1.8g / L fluorine. 3Sodium tungstate crystals are dissolved in water to obtain sodium tungstate solution, which enters the main process to prepare ammonium paratungstate products. Add 5 kg carbonate and 14 kg calcium oxide to the sodium hydroxide mother liquor, control the heating temperature at 85 ° C, stir and react for 1 hour, and then filter to obtain filter residue and low-fluorine sodium hydroxide solution containing 0.06 g / L fluorine. The low-fluorine sodium hydroxide solution is returned to the pulping and alkali boiling process.

[0050] Embodiment 2:

[0051] The high-fluorine tungsten ore containing 42.2% WO3 and 8.7% F was ball-milled to make its slurry particle size less than 325 mesh and greater than 95%. Sodium hydroxide was added to the obtained slurry to adjust the liquid-solid ratio to 1.2:1, and the adjusted slurry was added to the reactor for heating reaction. The reaction temperature was controlled at 150-180℃ and the reaction was carried out for 4 hours. The slurry with good reaction was placed in a dilution tank with water added. The dilution volume was 4 times the slurry volume and filtered. The filtered concentrated solution was concentrated by an evaporator. When the sodium hydroxide concentration in the concentrated solution reached 350g / L, the concentrated solution was cooled and filtered to obtain sodium tungstate crystals and 6m sodium hydroxide mother liquor containing 2.6g / L fluorine. 3 Sodium tungstate crystals are dissolved in water to obtain sodium tungstate solution, which enters the main process to prepare ammonium paratungstate products. Add 10 kg carbonate and 22 kg calcium oxide as defluoridation agent to the sodium hydroxide mother liquor, control the heating temperature at 90 ° C, stir and react for 1 hour, and then filter to obtain filter residue and low-fluorine sodium hydroxide solution containing 0.1 g / L fluorine. The sodium hydroxide solution is returned to the pulping and alkali boiling process.

[0052] Embodiment 3:

[0053] The high-fluorine tungsten ore containing 58.0% WO3 and 3.7% F was ball-milled to make its slurry particle size <325 mesh and greater than 95%. Sodium hydroxide was added to the obtained slurry to adjust the liquid-solid ratio to 1.2:1, and the adjusted slurry was added to the reactor for heating reaction. The reaction temperature was controlled at 140-180℃ and the reaction was carried out for 3.5 hours. The reacted slurry was placed in a dilution tank with water added, and the dilution volume was 3 times the slurry volume and filtered. The filtered concentrated solution was concentrated by an evaporator. When the sodium hydroxide concentration in the concentrated solution reached 340g / L, the concentrated solution was cooled and filtered to obtain sodium tungstate crystals and 5m sodium hydroxide mother liquor containing 1.6g / L fluorine. 3 Sodium tungstate crystals are dissolved in water to obtain sodium tungstate solution, which enters the main process to prepare ammonium paratungstate products. Add 6 kg carbonate and 16 kg calcium oxide to the sodium hydroxide mother liquor, control the heating temperature at 88 ° C, stir and react for 1 hour, and then filter to obtain filter residue and low-fluorine sodium hydroxide solution containing 0.07 g / L fluorine. The sodium hydroxide solution is returned to the pulping and alkali boiling process.

[0054] Embodiment 4:

[0055] The high-fluorine tungsten ore containing 36.4% WO3 and 11.2% F was ball-milled to make its slurry particle size less than 325 mesh and greater than 95%. Sodium hydroxide was added to the obtained slurry to adjust the liquid-solid ratio to 1.3:1, and the adjusted slurry was added to the reactor for heating reaction. The reaction temperature was controlled at 150-180℃ and the reaction was carried out for 3.5 hours. The reacted slurry was placed in a dilution tank with water added, and the dilution volume was 3.5 times the slurry volume and filtered. The filtered concentrated solution was concentrated by an evaporator. When the sodium hydroxide concentration in the concentrated solution reached 350g / L, the concentrated solution was cooled and filtered to obtain sodium tungstate crystals and 5m sodium hydroxide mother liquor containing 4.2g / L fluorine. 3 Sodium tungstate crystals are dissolved in water to obtain sodium tungstate solution, which enters the main process to prepare ammonium paratungstate products. Add 11 kg carbonate and 35 kg calcium oxide to the sodium hydroxide mother liquor, control the heating temperature at 85 ° C, stir and react for 1 hour, and then filter to obtain filter residue and 0.09 g / L low-fluorine sodium hydroxide solution, which is returned to the pulping and alkali boiling process.

[0056] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for removing fluorine from high-fluorine tungsten ore, comprising the following steps: Step S1: ball milling the high-fluorine tungsten ore to make its slurry particle size less than 325 mesh, and the obtained slurry enters the next process; Step S2: adding sodium hydroxide to the high-fluorine tungsten slurry ball-milled in step S1 to adjust the slurry to a liquid-solid ratio of 1.2:1-4:1, and adding the adjusted slurry to a reactor for heating reaction, the reaction temperature is controlled at 140-180°C, and the reaction is carried out for 3-4 hours; Step S3: Put the slurry reacted in step S2 into a dilution tank with water added, dilute the volume to 2-6 times the volume of the slurry and filter, concentrate the filtered concentrated solution through an evaporator, and when the sodium hydroxide concentration in the solution is greater than 300g / L, cool and filter the solution to obtain sodium tungstate crystals and high-fluorine sodium hydroxide mother liquor, the sodium tungstate crystals are dissolved in water to obtain a sodium tungstate solution that enters the main process for preparing ammonium paratungstate products, and the obtained high-fluorine sodium hydroxide mother liquor enters the next process; Step S4: adding a defluorinating agent to the high-fluorine sodium hydroxide mother liquor, heating and stirring the reaction for 1-2 hours, and then filtering to obtain a filter residue and a low-fluorine sodium tungstate solution, and the low-fluorine sodium hydroxide solution is returned to the slurry adjustment and alkali boiling process.

2. The method for defluorination of high-fluorine tungsten ore according to claim 1, characterized in that: In step S1, the high-fluorine tungsten ore contains 10.0-65.0% WO3 and 0.5-15.0% F; and the particle size of the tungsten ore is greater than 95.0% of 325 mesh.

3. The method for defluorination of high-fluorine tungsten ore according to claim 2, characterized in that: In the step S2, sodium hydroxide is added to adjust the slurry, and the amount of sodium hydroxide used is 1.5-4 times the theoretical amount.

4. The method for defluorination of high-fluorine tungsten ore according to claim 1, characterized in that: In step S2, the ore pulp is added into the reactor and heated for reaction at a temperature of 140-180° C. for 1-5 hours.

5. The method for defluorination of high-fluorine tungsten ore according to claim 1, characterized in that: In step S3, the solution is concentrated by an evaporator, and the concentration of sodium hydroxide in the solution is 300-500 g / L.

6. The method for defluorination of high-fluorine tungsten ore according to claim 1, characterized in that: In step S4, the defluorination agent is carbonate and calcium salt, the amount of carbonate added is 0.1%-0.5% of the solution mass, and the amount of calcium salt added is 1.5-3.0 times the theoretical amount of fluorine content in the solution; The carbonate is sodium carbonate and the calcium salt is calcium oxide.

7. The method for defluorination of high-fluorine tungsten ore according to claim 1, characterized in that: In step S4, the heating and stirring are performed at a temperature of 60-90°C.

8. The method for defluorination of high-fluorine tungsten ore according to claim 1, characterized in that: In step S2, the heating method in the reactor is one of electric heating, steam heating, far infrared heating or thermal oil heating.

9. The method for removing fluorine from high-fluorine tungsten ore according to claim 1, characterized in that: In step S3, the evaporator is used for concentration, and the evaporator is heated by steam or by thermal oil, and the evaporator is used by single effect, double effect, triple effect or multiple effect.

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