Method for recovering tungsten from aluminum salt phosphorus removal slag of sodium tungstate solution

Abstract

The invention relates to the technical field of tungsten smelting and waste residue recycling, in particular to a method for recycling tungsten from aluminum salt dephosphorization slag of a sodium tungstate solution, which comprises the following steps: S1, uniformly mixing the aluminum salt dephosphorization slag with activated carbon to obtain a mixture; s2, performing aerobic roasting on the mixture to obtain a roasted material; s3, adding a first volume of water and an alkali adjusting agent into the roasted material to obtain a premix, and performing wet grinding and crushing on the premix to obtain a wet grinding material; and S4, water is added into the wet grinding material to obtain a second volume of feed liquid, the feed liquid is heated to a preset temperature and subjected to heat preservation, filtering is conducted after cooling, and a sodium tungstate solution and filter residues are obtained. The method has the beneficial effects that the tungsten in the aluminum salt dephosphorization slag is recycled; the method has the advantages of being short in technological process, efficient and low in cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tungsten smelting and waste residue recycling, and particularly relates to a method for recovering tungsten from aluminum salt dephosphorization residue of a sodium tungstate solution. BACKGROUND

[0002] In the smelting process of tungsten, a sodium tungstate solution is a common intermediate product. However, in the preparation and subsequent treatment process of the sodium tungstate solution, impurity elements such as phosphorus are often introduced. In production, calcium salts, magnesium salts, aluminum salts and the like are usually used for dephosphorization. Aluminum salt dephosphorization residue is waste residue generated in the treatment process of the sodium tungstate solution, which is generated by adding aluminum salts (such as sodium aluminate, aluminum chloride and the like) to react with phosphate ions in the solution to generate insoluble aluminum phosphate precipitate, thereby achieving the purpose of dephosphorization. These waste residues usually contain a high content of tungsten elements, which have significant recycling value.

[0003] Researchers have conducted related research in the prior art. For example, a Chinese patent with the publication number CN115679128A discloses a method for efficiently recovering tungsten and ammonia from tungsten-containing dephosphorization precipitate residue, which includes the following steps: acid dissolution, adding dephosphorization residue into acid solution, and adjusting the pH value to less than 2 by water to achieve full dissolution of the residue so that tungsten can enter the solution as much as possible, after settling, the supernatant is separated and purified by resin adsorption to separate and purify tungsten in the solution. After the exchange, the liquid is added to the alkali solution to precipitate the metal ions, and after filtration, the filtrate is heated to volatilize the ammonia, and ammonia is recovered by condensation to obtain ammonia water. This method has a long process, and acid and alkali are required to recover tungsten and ammonia. Moreover, the method of heating and volatilizing ammonia causes a large amount of water vapor to be mixed with ammonia gas due to the water vapor brought in by water vapor, and the ammonia concentration of the ammonia liquid recovered by condensation is relatively low, which is not conducive to returning to production. This method is not suitable for aluminum salt dephosphorization residue, because in the acid dissolution, the aluminum salt dephosphorization residue will react with the acid to generate aluminum chloride and sodium metatungstate dissolved in the solution, and the separation of tungsten and aluminum cannot be achieved.

[0004] A Chinese patent with the publication number CN109881012A discloses a treatment method for recovering tungsten from dephosphorization residue in tungsten metallurgy, which includes the following steps: the dephosphorization residue is slurried with water and heated to 40-90℃; then dilute acid is added to adjust the pH to 2-4, and stirred for 0.5-4h; filtration is performed to obtain a decomposition liquid and a small amount of undecomposed residue, the undecomposed residue is returned to the slurry heating step for continuous decomposition, and the valuable metal tungsten enters the decomposition liquid; then the decomposition liquid is subjected to macroporous anion exchange resin adsorption to recover tungsten, and then alkali desorption is performed to obtain a sodium tungstate solution for subsequent process use. This method is not suitable for aluminum salt dephosphorization residue, because in the acid dissolution, the aluminum salt dephosphorization residue will react with the acid to generate aluminum chloride and sodium metatungstate dissolved in the solution, and the separation of tungsten and aluminum cannot be achieved.

[0005] A tungsten smelting phosphorus removal slag treatment method is disclosed in Chinese Patent No. CN103451434B, which is mainly a method for extracting and separating tungsten from the tungsten-containing phosphorus removal slag generated in the dephosphorization process of ammonium paratungstate production. Specifically, the phosphorus removal slag generated in the dephosphorization process of ammonium paratungstate production is immersed in an aqueous solution, a specific leaching agent and an activator are used, and after sufficient reaction in a reaction kettle, a decomposition solution and a phosphorus removal decomposition residue are obtained by filtration. The phosphorus removal decomposition residue contains WO3≤1.5% after washing, and the generated decomposition solution enters the subsequent tungsten extraction process. The comprehensive utilization rate of mineral resources is improved, the recovery rate of valuable metal tungsten is high, and the process flow of tungsten reuse is shortened. Chinese Patent No. CN118637664B discloses a tungsten smelting phosphorus removal slag treatment method and application, which directly recovers WO3 in tungsten smelting phosphorus removal slag by high-concentration alkali leaching. The leached sodium tungstate does not need to be dephosphorized and can be directly used. After leaching WO3, concentrated sulfuric acid is added to the phosphorus removal slag for activation. The activated phosphorus removal slag can be used for dephosphorization of sodium tungstate solution.

[0006] Chinese Patent No. CN118684267A discloses a tungsten acid ammonium solution phosphorus removal slag treatment method. The method realizes the transformation of the phosphorus removal slag by oxygen roasting after drying the tungsten acid ammonium solution phosphorus removal slag to obtain transformed slag. The transformed slag is mixed with a decomposition-promoting reagent and then subjected to high-temperature high-pressure ammonia dissolution. After solid-liquid separation, tungsten acid ammonium solution is obtained. This method not only obtains relatively pure tungsten acid ammonium solution, but also leaches tungsten while not leaching phosphorus. The tungsten acid ammonium solution can be directly returned to the main process for use. In addition, this method does not produce ammonia-nitrogen waste liquid, reducing the treatment pressure of waste water and production cost. The WO3 content in the ammonia-dissolved slag is high, and secondary recovery is required.

[0007] Currently, there is no method for recovering tungsten from tungsten sodium solution aluminum salt phosphorus removal slag in the prior art. The tungsten sodium solution aluminum salt phosphorus removal slag contains aluminum hydroxide colloid and a large amount of sodium tungstate solution. When recovering sodium tungstate solution, the aluminum hydroxide colloid makes it difficult to recover the sodium tungstate solution. SUMMARY

[0008] To solve the above technical problems, the present application provides a method for recovering tungsten from tungsten sodium solution aluminum salt phosphorus removal slag, comprising the following steps: S1, uniformly mixing aluminum salt phosphorus removal slag and activated carbon to obtain a mixture; S2, oxygen roasting the mixture to obtain a roasted material; S3, adding a first volume of water and an alkali adjusting agent to the roasted material to obtain a premix, wet grinding and crushing the premix to obtain a wet ground material; S4, adding water to the wet ground material to obtain a second volume of slurry, heating to a preset temperature and maintaining the temperature, cooling and filtering to obtain a sodium tungstate solution and a filter residue.

[0009] As a preferred scheme of the method for recovering tungsten from the aluminum salt dephosphorization residue in the sodium tungstate solution according to the application, in step S1, the water content of the aluminum salt dephosphorization residue is 38wt%-42wt%.

[0010] As a preferred scheme of the method for recovering tungsten from the aluminum salt dephosphorization residue in the sodium tungstate solution according to the application, in step S1, the mesh number of the activated carbon is 200-400, and the mass ratio of the activated carbon to the aluminum salt dephosphorization residue is 1:100-2:100. Preferably, the mass ratio of the activated carbon to the aluminum salt dephosphorization residue is any one or a range between any two of 1.0:100, 1.2:100, 1.4:100, 1.6:100, 1.8:100, and 2.0:100.

[0011] As a preferred scheme of the method for recovering tungsten from the aluminum salt dephosphorization residue in the sodium tungstate solution according to the application, in step S2, the temperature of the roasting is 900-1200℃, and the time of the roasting is 2-4h. Preferably, the temperature of the roasting is any one or a range between any two of 900℃, 1000℃, 1100℃, and 1200℃. Preferably, the time of the roasting is any one or a range between any two of 2.0h, 2.5h, 3.0h, 3.5h, and 4.0h.

[0012] As a preferred scheme of the method for recovering tungsten from the aluminum salt dephosphorization residue in the sodium tungstate solution according to the application, in step S3, the ratio of the first volume to the mass of the aluminum salt dephosphorization residue is (0.5-1.5)mL:1g. Preferably, the ratio of the first volume to the mass of the aluminum salt dephosphorization residue is any one or a range between any two of 0.5mL:1g, 0.6mL:1g, 0.7mL:1g, 0.8mL:1g, 0.9mL:1g, 1.0mL:1g, 1.1mL:1g, 1.2mL:1g, 1.3mL:1g, 1.4mL:1g, and 1.5mL:1g.

[0013] As a preferred scheme of the method for recovering tungsten from the aluminum salt dephosphorization residue in the sodium tungstate solution according to the application, in step S3, the alkali adjusting agent includes at least one of a soluble carbonate, a soluble bicarbonate, sodium hydroxide, and potassium hydroxide, and the pH of the premix is 9-14.

[0014] As a preferred scheme of the method for recovering tungsten from the aluminum salt dephosphorization residue in the sodium tungstate solution according to the application, in step S4, the ratio of the second volume to the mass of the aluminum salt dephosphorization residue is (2.5-5)mL:1g.

[0015] Preferably, the ratio of the second volume to the mass of the aluminum salt dephosphorization slag is any one of 2.5mL:1g, 3mL:1g, 3.5mL:1g, 4mL:1g, 4.5mL:1g, 5mL:1g, or a range between two of them.

[0016] As a preferred embodiment of the method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to the present invention, in step S4, a water bath is used for heating, the preset temperature is 60~100℃, and the holding time is 1~2h. Preferably, the preset temperature is any one of 60℃, 70℃, 80℃, 90℃, 100℃, or a range between two of them.

[0017] As a preferred embodiment of the method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to the present invention, the tungsten recovery rate is greater than or equal to 98%.

[0018] The beneficial effects of this invention are as follows: This invention proposes a method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution. The aluminum salt dephosphorization slag is uniformly mixed with activated carbon, and then the aluminum hydroxide colloid in the slag is converted into porous α-Al₂O₃, which is sparingly soluble in water and alkali, through high-temperature calcination. Next, water and an alkali adjuster are added for wet grinding and crushing. Then, water is added for dilution and heating, and finally, solid-liquid separation is performed to obtain a solid slag containing elements such as aluminum, iron, calcium, and phosphorus, as well as a sodium tungstate solution, thereby achieving the recovery of tungsten from the aluminum salt dephosphorization slag. This invention achieves a tungsten recovery rate greater than 98% and has the advantages of a short process flow, high efficiency, and low cost. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of the method for recovering tungsten from the phosphorus removal slag of sodium tungstate solution aluminum salt according to the present invention.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1 , Figure 1 This is a schematic flowchart of the method for recovering tungsten from the dephosphorization slag of sodium tungstate solution aluminum salt according to the present invention. The present invention proposes a method for recovering tungsten from the dephosphorization slag of sodium tungstate solution aluminum salt, comprising the following steps: S1. Mix aluminum salt dephosphorization slag with activated carbon evenly to obtain a mixture; In the aluminum salt dephosphorization slag of sodium tungstate, aluminum mainly exists in the form of aluminum hydroxide colloid. The negatively charged surface of the aluminum hydroxide colloid causes the colloidal particles to flocculate and agglomerate, forming a three-dimensional network of loose flocs. A large amount of free sodium tungstate solution is physically encapsulated within the pores of this floc structure.

[0024] The purpose of adding activated carbon in this invention is to obtain porous α-Al2O3 by calcination in step S2; S2. The mixture is calcined under aerobic conditions to obtain calcined material; During the roasting process, the aluminum hydroxide colloid coated with sodium tungstate is first converted into hygroscopic and alkali-sensitive γ-Al2O3, and finally into porous α-Al2O3, which is sparingly soluble in water and weak alkalis. The porous structure is conducive to the diffusion and leaching of sodium tungstate in steps S3 and S4. The conversion of aluminum hydroxide colloid into α-Al2O3 can inhibit the leaching of aluminum in steps S3 and S4, thereby achieving the purpose of separating tungsten and aluminum. The chemical composition of sodium tungstate and aluminum phosphate in the residue remains unchanged before and after roasting. S3. Add a first volume of water and alkali adjuster to the roasted material to obtain a premix, and then wet grind the premix to obtain a wet ground material. In step S3, sodium tungstate is partially leached under alkaline conditions. Sodium tungstate will form paratungstate when the pH value is 4-6, and will form metatungstate when the pH value is less than 4. Alkaline conditions can prevent sodium tungstate from being converted into large molecular clusters of paratungstate that are easily adsorbed by porous α-Al2O3 under neutral conditions, making it difficult to leach. S4. Add water to the wet abrasive to obtain a second volume of liquid material, heat it to a preset temperature and keep it at that temperature, cool it and then filter it to obtain a sodium tungstate solution and filter residue. Diluting with water and then heating can accelerate the diffusion of sodium tungstate from the porous structure. The main components of the solid slag are Al2O3, aluminum phosphate, and vanadium-iron-aluminum impurities.

[0025] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0026] The sodium tungstate solution used in the embodiments and comparative examples of this invention for dephosphorizing aluminum salts mainly consists of water, sodium tungstate, aluminum phosphate, aluminum hydroxide, and impurities such as vanadium, iron, and calcium. XRF analysis of the dried aluminum salt dephosphorizing slag revealed the following composition: Example 1 A method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution includes the following steps: S1. The aluminum salt dephosphorization slag and activated carbon are mixed evenly to obtain a mixture; wherein the aluminum salt dephosphorization slag has a moisture content of 39.8 wt% and a mass of 200 g; the activated carbon has a mesh size of 200 and a mass of 2.0 g; the mixture is stirred evenly using mechanical stirring. S2. The mixture is calcined with oxygen to obtain calcined material; wherein the mixture is placed in a crucible and calcined in a muffle furnace at a calcination temperature of 900°C for 2 hours. S3. Add a first volume of water and an alkali adjuster to the calcined material to obtain a premix. Wet-mill the premix to obtain wet-milled material. The calcined material is placed in a planetary ball mill jar with a ball-to-material ratio of 8:1, a first volume of 200mL, and an alkali adjuster of 10g sodium carbonate to obtain a premix with a pH of 12. Wet-mill for 120min to obtain wet-milled material.

[0027] S4. Add water to the wet abrasive to obtain a second volume of liquid material, heat to a preset temperature and keep warm, cool and filter to obtain sodium tungstate solution and filter residue; wherein, the second volume is 500 mL, the preset temperature is 90℃, and the holding time is 1 h.

[0028] Experimental results: The filter residue was washed with water, dried and weighed to obtain 24.22g. The WO3 content in the residue was detected to be 6.30wt%, and the WO3 recovery rate was 98.10%.

[0029] Example 2 The difference from Example 1 is that in step S2, the calcination temperature is 1000℃ and the calcination time is 4h; in step S3, the first volume is 300mL.

[0030] Experimental results: The filter residue was washed with water, dried and weighed to obtain 23.85g. The WO3 content in the residue was tested to be 4.74wt%, and the WO3 recovery rate was 98.60%.

[0031] Example 3 The difference from Example 1 is that: in step S1, the mass of activated carbon is 3.0g; in step S2, the calcination temperature is 1100℃ and the calcination time is 4h; in step S3, the first volume is 100mL.

[0032] Experimental results: The filter residue was washed with water, dried and weighed to obtain 23.66g. The WO3 content in the residue was tested to be 3.55wt%, and the WO3 recovery rate was 98.96%.

[0033] Example 4 The difference from Example 1 is as follows: in step S1, the mass of activated carbon is 3.0g; in step S2, the calcination temperature is 1200℃ and the calcination time is 2h; in step S3, the alkali adjuster is 8g of sodium carbonate, and a premix with a pH of 11.6 is obtained.

[0034] Experimental results: The filter residue was washed with water, dried and weighed to obtain 22.30g. The WO3 content in the residue was tested to be 2.53wt%, and the WO3 recovery rate was 99.30%.

[0035] Example 5 The difference from Example 1 is as follows: in step S1, the mass of activated carbon is 4.0g; in step S2, the calcination temperature is 1200℃ and the calcination time is 4h; in step S3, the alkali adjuster is 8g of sodium carbonate, and a premix with a pH of 11.6 is obtained.

[0036] Experimental results: The filter residue was washed with water, dried and weighed to obtain 22.30g. The WO3 content in the residue was tested to be 2.03wt%, and the WO3 recovery rate was 99.44%.

[0037] Example 6 The difference from Example 1 is as follows: in step S1, the mass of activated carbon is 4.0g; in step S2, the calcination temperature is 1100℃ and the calcination time is 4h; in step S3, the alkali adjuster is 8g of sodium carbonate, and a premix with a pH of 11.6 is obtained; in step S4, the preset temperature is 80℃ and the holding time is 1h.

[0038] Experimental results: The filter residue was washed with water, dried and weighed to obtain 22.45g. The WO3 content in the residue was tested to be 2.87wt%, and the WO3 recovery rate was 99.20%.

[0039] Comparative Example 1 The difference from Example 1 is that: in step S1, the mass of activated carbon is 4.0g; in step S2, the calcination temperature is 700℃ and the calcination time is 4h; in step S4, the preset temperature is 80℃ and the holding time is 1h.

[0040] Experimental results: The filter residue was washed with water, dried and weighed to obtain 46.54g. The WO3 content in the residue was tested to be 26.00wt%, and the WO3 recovery rate was 85.00%.

[0041] Comparative Example 2 The difference from Example 1 is that: in step S1, activated carbon is not added to mix with the phosphorus removal slag; in step S2, the calcination temperature is 1000℃ and the calcination time is 4h; in step S4, the preset temperature is 100℃ and the holding time is 1h.

[0042] Experimental results: The filter residue was washed with water, dried and weighed to obtain 28.15g. The WO3 content in the residue was tested to be 27.46wt%, and the WO3 recovery rate was 90.42%.

[0043] Comparative Example 3 The difference from Example 1 is that: in step S1, activated carbon is not added to mix with the phosphorus removal slag; in step S2, the calcination temperature is 600℃ and the calcination time is 4h; in step S4, the preset temperature is 100℃ and the holding time is 1h.

[0044] Experimental results: The filter residue was washed with water, dried and weighed to obtain 50.74g. The WO3 content in the residue was tested to be 62.25wt%, and the WO3 recovery rate was 60.84%.

[0045] Comparative Example 4 Unlike Example 1, no alkali adjuster is added in step S3.

[0046] Experimental results: The filter residue was washed with water, dried and weighed to obtain 26.77g. The WO3 content in the residue was tested to be 14.51wt%, and the WO3 recovery rate was 95.18%.

[0047] Comparative Example 5 The difference from Example 1 is as follows: in step S1, the activated carbon has a mesh size of 100 mesh; in step S3, the first volume is 100 mL, the alkali adjuster is 1 g sodium hydroxide, and a premix with a pH of 13.4 is obtained; in step S4, the second volume is 300 mL, the preset temperature is 60℃, and the heat preservation time is 0.5 h.

[0048] Experimental results: The filter residue was washed with water, dried and weighed to obtain 25.47g. The WO3 content in the residue was tested to be 9.31wt%, and the WO3 recovery rate was 97.06%.

[0049] As can be seen from the above embodiments and comparative examples, the present invention proposes a method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution. After the aluminum salt dephosphorization slag is mixed evenly with activated carbon, the aluminum hydroxide colloid in the aluminum salt dephosphorization slag is converted into porous α-Al2O3, which is sparingly soluble in water and weak alkali, by high-temperature calcination. Then, water and alkali adjuster are added for wet grinding and crushing, followed by dilution with water and heating. Finally, solid-liquid separation is performed to obtain solid slag containing elements such as aluminum, iron, calcium, and phosphorus, as well as sodium tungstate solution, thereby realizing the recovery of tungsten from aluminum salt dephosphorization slag. The tungsten recovery rate of the present invention is greater than 98%, and it has the advantages of short process flow and high efficiency and low cost.

[0050] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution, characterized in that, Includes the following steps: S1. Mix aluminum salt dephosphorization slag with activated carbon evenly to obtain a mixture; S2. The mixture is calcined under aerobic conditions to obtain calcined material; S3. Add a first volume of water and alkali adjuster to the roasted material to obtain a premix, and then wet grind the premix to obtain a wet ground material. S4. Add water to the wet abrasive to obtain a second volume of liquid material, heat to a preset temperature and keep warm, cool and filter to obtain sodium tungstate solution and filter residue.

2. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S1, the water content of the aluminum salt dephosphorization slag is 38wt%~42wt%.

3. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S1, the activated carbon has a mesh size of 200-400, and the mass ratio of the activated carbon to the aluminum salt dephosphorization slag is 1:100-2:

100.

4. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S2, the roasting temperature is 900~1200℃ and the roasting time is 2~4h.

5. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S3, the ratio of the first volume to the mass of the aluminum salt dephosphorization slag is (0.5~1.5) mL:1g.

6. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S3, the alkali adjuster includes at least one of alkaline potassium or sodium salts, and the pH of the premix is ​​9-14.

7. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S4, the ratio of the second volume to the mass of the aluminum salt dephosphorization slag is (2.5~5) mL:1g.

8. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, In step S4, a water bath is used for heating, the preset temperature is 60~100℃, and the heat preservation time is 1~2h.

9. The method for recovering tungsten from aluminum salt dephosphorization slag in sodium tungstate solution according to claim 1, characterized in that, The tungsten recovery rate is greater than or equal to 98%.

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