Method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag

Abstract

The application discloses a method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag, and aims at solving the problems that the existing method for recovering valuable metals from the tungsten slag needs a high temperature and the recovery rate of the valuable metals tungsten and tin needs to be improved. The recovery method comprises the following steps: S1, stirring and uniformly mixing tungsten slag powder with a reducing agent and a sulfidizing agent A; S2, placing the slag agent mixture of S1 in a tube furnace to perform high-temperature reduction treatment; S3, performing slag sulfuric acid leaching treatment; S4, repeatedly performing the high-temperature reduction treatment and the sulfuric acid leaching treatment for multiple times by taking the acid leaching slag as a sulfidizing agent B; and S5, stirring the tungsten-enriched sulfidized slag with sodium hydroxide and then roasting, obtaining a sodium tungstate solution through water leaching of the product, and finally evaporating and crystallizing. The valuable metal tin in the hazardous waste tungsten slag is extracted through high-temperature sulfidizing reduction. In the sulfidizing reduction reaction, tin is recovered, lead and arsenic oxides are oxidized to form sulfides, and the sulfides are separated from scheelite slag and enter the flue dust, and iron and manganese oxides are subjected to sulfidizing reduction reaction to enter the slag system, so that the hazardous waste is harmlessly treated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling, and particularly relates to a process method for recovering valuable metals tungsten and tin from tungsten slag hazardous waste. BACKGROUND

[0002] When tungsten ore is decomposed by sodium alkali pressure boiling method, tungsten is converted into soluble sodium tungstate into the solution, and through filtration, alkali decomposition pressure boiling residue, commonly known as tungsten slag, is obtained. Elements such as iron, manganese, scandium, molybdenum, tantalum, niobium, lead and arsenic associated with tungsten ore enter the tungsten slag. The tungsten content in the tungsten slag is continuously reduced with the development of tungsten smelting process level. The tungsten oxide content in the old tungsten slag in stock is as high as 5% or more. The tungsten oxide content in the current new tungsten slag is between 1% and 3%. Compared with the tungsten content of 0.2% to 0.3% in the raw ore, the grade of the tungsten slag is more than 10 times higher than that of the tungsten raw ore. At the same time, the tungsten slag contains valuable metal element tin, which accounts for about 0.4% to 1.5% in the tungsten slag. Therefore, the tungsten slag can be used as a secondary resource of tungsten and tin and has recycling value. Research on the recovery of valuable metals in the tungsten slag can on the one hand treat the stockpiled tungsten slag and reduce the impact on the environment, and on the other hand can alleviate the decreasing of mineral resources.

[0003] Some methods for recovering valuable metals from tungsten slag are disclosed in the prior art. For example, Chinese patent CN113737027A discloses a method for recovering valuable metals tungsten, iron and manganese from tungsten-containing slag material. After high-temperature reduction smelting with limestone and carbon reducing agent, tungsten is further reacted with an alkaline oxidizing agent at high temperature under oxygen-rich conditions to form tungstate salt dross and separate from iron-manganese alloy. Finally, sodium tungstate product is obtained by leaching. However, this method requires secondary high-temperature, and the first high-temperature reaches 1200-1400℃, which has high energy consumption. For example, Chinese patent CN115261627A discloses a method for recovering tin and tungsten from scheelite leaching residue and recovering sodium sulfite. White tungsten slag, sodium sulfate and anthracite material are reduced and smelted at a high temperature of 1400-1500℃. Tin is volatilized into flue gas in the form of stannous sulfide, and reduced slag is obtained by further water quenching and ball milling. Sodium tungstate product is obtained by leaching. However, this method requires a relatively high temperature, and the highest tin recovery rate is only 85.84%, and the tungsten metal recovery rate is 78.65%. SUMMARY

[0004] The present application is to solve the problem that the existing method for recovering valuable metals from tungsten slag requires a relatively high temperature, and the recovery rate of valuable metals tungsten and tin needs to be improved. A method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag is provided, which simultaneously realizes the harmless and resourceful treatment of tungsten slag.

[0005] The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to the present application is realized according to the following steps:

[0006] S1, the tungsten slag powder after fine grinding and drying is fully stirred with a reducing agent and a sulfidizing agent A to obtain a slag agent mixture;

[0007] S2, the slag agent mixture in S1 is placed in a heating zone of a tube furnace, a quartz filter screen is placed at a condensing end of the tube furnace, a heating mode is started, high-temperature reduction treatment is performed at 800-1200 DEG C, and the reduction furnace slag and tin-containing smoke dust on the quartz filter screen are collected after cooling to room temperature;

[0008] S3, the reduction furnace slag in S2 is broken, and then sulfuric acid leaching treatment is performed, and acid leaching slag is obtained after sulfuric acid leaching and filtration;

[0009] S4, the acid leaching slag obtained in S3 is used as a sulfidizing agent B, and is fully mixed with the tungsten slag powder and the reducing agent, and the high-temperature reduction treatment of S2 and the sulfuric acid leaching treatment of S3 are repeated multiple times, and finally high-temperature reduction treatment is performed to obtain tungsten-enriched sulfidized slag;

[0010] S5, the tungsten-enriched sulfidized slag obtained in S4 is uniformly stirred with sodium hydroxide, is placed in a crucible, and is calcined at 700 DEG C, the calcined product is immersed in water and filtered, a sodium tungstate solution is obtained, the filtrate is evaporated and crystallized to obtain sodium tungstate crystals, and thus the valuable metals tungsten and tin in the tungsten slag are recovered;

[0011] The reducing agent is carbon particles, carbon powder or activated carbon, and the sulfidizing agent A is calcium sulfate.

[0012] The application uses high-temperature sulfidizing reduction to react tin dioxide in white tungsten slag to generate low-boiling-point stannous sulfide which is volatilized into smoke and separated from the slag. The high-temperature sulfidizing reduction process not only achieves the purpose of recovering tin in the tungsten slag, but also harmless treats the white tungsten slag, and can realize the dual effects of resource utilization and environmental protection.

[0013] 2SnO2+2CaSO4+5C=2SnS↑+2CaO+5CO2↑

[0014] PbO+CaSO4+2C=PbS↑+CaO+2CO2↑

[0015] 2As2O3+4CaSO4+9C=4AsS↑+4CaO+9CO2↑

[0016] 2Fe2O3+4CaSO4+9C=4FeS+4CaO+9CO2↑

[0017] 2MnO2+2CaSO4+5C=2MnS+2CaO+5CO2↑

[0018] The sulfidation slag is further subjected to sulfuric acid leaching, the iron and manganese compounds in the sulfidation slag react with sulfuric acid to become ions in the solution, and calcium generates calcium sulfate precipitate, and calcium tungstate is basically insoluble in dilute sulfuric acid. After leaching, the tungsten-containing slag mainly containing calcium sulfate is obtained by filtration. The calcium sulfate containing tungsten slag can be recycled to high-temperature sulfidation reduction of scheelite slag by replacing lime, and with the increase of the number of cycles, tungsten is enriched in the slag system, and finally sodium tungstate is recovered by alkali decomposition.

[0019] FeO+H2SO4=H2O+FeSO4

[0020] MnS+H2SO4=MnSO4+H2S

[0021] CaO+H2SO4=CaSO4+H2O

[0022] FeS+H2SO4=H2S+FeSO4

[0023] Compared with the prior art, the beneficial effects of the present application are that the valuable metal tin in the hazardous waste tungsten slag is extracted by high-temperature sulfidation reduction. The sulfidation reduction reaction recovers tin, and lead and arsenic oxides generate sulfides and are separated from scheelite slag, which also enters the flue dust, and iron and manganese oxides undergo sulfidation reduction reaction to generate sulfides and enter the slag system, achieving harmless treatment of hazardous waste. In addition, the waste slag is recycled after acid leaching treatment, and tungsten enrichment is realized through multiple cycles. Further alkali decomposition of tungsten-enriched slag can recover tungsten. The present application not only achieves the purpose of recovering tin and tungsten resources from tungsten slag, but also harmless treatment of scheelite slag, which can play a dual role of resource utilization and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The process flow diagram for recovering valuable metals tungsten and tin from hazardous waste tungsten slag of the present application. DETAILED DESCRIPTION

[0025] Specific implementation method one: the method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag in the present embodiment is implemented according to the following steps:

[0026] S1, the finely ground and dried tungsten slag powder is fully stirred and mixed with a reducing agent and a sulfidizing agent A to obtain a slag agent mixture;

[0027] S2, the slag agent mixture in step S1 is placed in the heating zone of a tube furnace, a quartz filter screen is placed on the condensing end of the tube furnace, the heating mode is started, and the temperature is heated to 800-1200 DEG C for high-temperature reduction treatment, and then cooled to room temperature. The reduction furnace slag and the tin-containing flue dust on the quartz filter screen are collected;

[0028] S3, crushing the reduced furnace slag in step S2, and then performing sulfuric acid leaching treatment, to obtain an acid leaching residue by filtering the sulfuric acid leaching;

[0029] S4, mixing the acid leaching residue obtained in step S3 as a sulfidizing agent B with tungsten slag powder and a reducing agent, and repeatedly performing the high-temperature reduction treatment of step S2 and the sulfuric acid leaching treatment of step S3 for multiple times, and finally performing high-temperature reduction treatment to obtain a tungsten-enriched sulfidized residue;

[0030] S5, uniformly stirring the tungsten-enriched sulfidized residue obtained in step S4 with sodium hydroxide, and then placing the mixture in a crucible to perform calcination at 700°C, and obtaining a sodium tungstate solution by filtering the calcination product after water leaching, and obtaining sodium tungstate crystals by evaporating and crystallizing the filtrate, thereby completing the recovery of valuable metals tungsten and tin from the tungsten slag;

[0031] The reducing agent is carbon particles, carbon powder or activated carbon, and the sulfidizing agent A is calcium sulfate.

[0032] The embodiment provides a sulfidation-reduction-acid leaching cycle-sodium alkali melting-water leaching-evaporative crystallization process for recovering tin and tungsten in white tungsten slag. The process is as follows: calcium sulfate, carbon particles and white tungsten slag are mixed to obtain a mixture, and the mixture is calcined by high-temperature sulfidation reduction process to obtain stannous sulfide dust, so as to realize the separation and enrichment of tin elements. The stannous sulfide dust is used as a product and sold to a tin smelting enterprise. The reduced slag is further subjected to sulfuric acid leaching to obtain a tungsten-containing acid leaching residue mainly composed of calcium sulfate, and the tungsten-containing acid leaching residue is used as calcium sulfate for high-temperature sulfidation reduction, so as to achieve the purpose of tungsten enrichment. Finally, the tungsten-enriched slag is subjected to sodium hydroxide sodium melting-water leaching-evaporative crystallization process to obtain sodium tungstate crystals.

[0033] The embodiment can separate toxic metal elements lead and arsenic in white tungsten slag while recovering tin and tungsten in the white tungsten slag, and simultaneously realize resource utilization and harmless treatment of the white tungsten slag.

[0034] Specific embodiment two: different from the specific embodiment one, the particle size of the tungsten slag powder after fine grinding in step S1 is 1-10 μm.

[0035] Specific embodiment three: different from the specific embodiment one or two, in the tungsten slag powder in step S1, the mass fraction of Sn is 0.5%-1.5%, the mass content of W is 1%-5%, the mass content of Ca is 10%-40%, the mass content of Fe is 10%-30%, the mass content of Mn is 5%-15%, the mass content of Si is 5%-10%, the mass content of Nb is 0.5%-2%, and the mass content of Ta is 1%-5%.

[0036] Specific embodiment four: different from any one of the specific embodiments one to three, the mass ratio of the tungsten slag powder to the reducing agent in step S1 is (1-20):1.

[0037] In this embodiment, the optimized mass ratio of tungsten slag powder to reducing agent is (5-10):1.

[0038] Specific Implementation Method 5: This implementation method differs from Specific Implementation Method 4 in that the mass ratio of tungsten slag powder to sulfiding agent A in step S1 is 100:(4-15).

[0039] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the high-temperature reduction treatment time in step S2 is 1 to 3 hours.

[0040] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Five in that, in step S3, during the sulfuric acid leaching process, the reducing residue and sulfuric acid with a mass percentage of 20% are leached at a liquid-to-solid ratio of 5 mL to 15 mL / g, the leaching temperature is 60 to 95°C, and the leaching time is 1 to 4 hours.

[0041] Specific Implementation Method Eight: This implementation method differs from one of the specific implementation methods one to seven in that the mass ratio of sulfiding agent B to tungsten slag in step S4 is (1-2):(1-2).

[0042] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the mass ratio of tungsten-enriched acid leaching residue to sodium hydroxide in step S5 is 1:(1.1~3), and it is calcined at 700℃ for 2 hours.

[0043] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the water immersion temperature in step S5 is 90°C and the water immersion time is 4 hours.

[0044] Example 1: The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag in this example is implemented according to the following steps:

[0045] S1. Using tungsten slag (white) produced by a tungsten smelter in Hunan as raw material, 100g of finely ground and dried tungsten slag powder is thoroughly mixed with 10g of carbon particles and 4.1g of calcium sulfate to obtain a slag-agent mixture.

[0046] S2. Place the slag-agent mixture from step S1 into the heating zone of the tubular furnace, place the quartz filter screen at the condensing end of the tubular furnace, start the heating mode, heat to 1200℃ for high-temperature reduction treatment for 1 hour, cool to room temperature, and collect the reduced slag and the dust on the quartz filter screen.

[0047] Analysis of the slag and dust enriched with valuable metals was performed. According to ICP-AES testing, the tin volatilization rate was calculated to be 90.03%, indicating a high recovery rate.

[0048] Example 2: The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag is implemented according to the following steps:

[0049] S1, taking tungsten slag generated by a tungsten smelting plant in Hunan as raw material, 100g of finely ground and dried tungsten slag powder is fully stirred and mixed with 20g of carbon particles and 4.1g of calcium sulfate to obtain a slag agent mixture;

[0050] S2, the slag agent mixture in step S1 is placed in the heating zone of the tube furnace, a quartz filter screen is placed at the condensing end of the tube furnace, the heating mode is started, heated to 1200℃ for high temperature reduction treatment for 1h, cooled to room temperature, and the reduced slag and the dust on the quartz filter screen are collected.

[0051] The obtained slag and dust enriched in valuable metals are analyzed, and the main component of the recovered dust is SnS by ICP-AES test, and the content of tin in the dust is 60.62%. By calculation, the volatilization rate of tin is 96.79%, and the recovery rate is high.

[0052] Example 3: The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag is implemented according to the following steps:

[0053] S1, taking tungsten slag generated by a tungsten smelting plant in Hunan as raw material, 100g of finely ground and dried tungsten slag powder is fully stirred and mixed with 20g of carbon particles and 4.1g of calcium sulfate to obtain a slag agent mixture;

[0054] S2, the slag agent mixture in step S1 is placed in the heating zone of the tube furnace, a quartz filter screen is placed at the condensing end of the tube furnace, the heating mode is started, heated to 1200℃ for high temperature reduction treatment for 1h, cooled to room temperature, and the reduced slag and the dust on the quartz filter screen are collected.

[0055] S3, the reduced slag in step S2 is crushed, then 20% sulfuric acid by mass percentage is used for leaching at 95℃ for 1h under the condition of liquid-solid ratio of 5mL / g, the sulfuric acid leaching filtrate is obtained, and the particle size is controlled to be more than 98% passing through a 320 mesh sieve after fine grinding;

[0056] S4, 25g of the acid leaching slag obtained in step S3 is used as sulfidizing agent B, and is fully mixed with 50g of scheelite slag powder and 5g of carbon particles, and the high temperature reduction treatment of step S2 is repeated to obtain tungsten-enriched sulfidized slag;

[0057] S5, 5g of the tungsten-enriched sulfidized slag obtained in step S4 is uniformly stirred with 10g of sodium hydroxide, and then is placed in a crucible and calcined at 700℃ for 2h, the calcined product is ground, and then is immersed in water at 90℃ for 4h, the filtrate is evaporated and crystallized to obtain sodium tungstate crystals, thereby completing the recovery of valuable metals tungsten and tin from tungsten slag.

[0058] The obtained valuable metal-enriched fumes are analyzed, and the volatilization rate of tin is calculated to be 96.79% by ICP-AES test, and the recovery rate is high. 0.54 g of sodium tungstate is collected from 5 g of enrichment slag, and the average grade of sodium tungstate is 90.05%.

[0059] Example 4: The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag is implemented according to the following steps:

[0060] S1, taking the tungsten slag generated by a tungsten smelting plant in Hunan as raw material, 100 g of finely ground and dried tungsten slag powder is fully stirred and mixed with 20 g of carbon particles and 4.1 g of calcium sulfate to obtain a slag agent mixture;

[0061] S2, the slag agent mixture in step S1 is placed in the heating zone of the tube furnace, a quartz filter screen is placed at the condensing end of the tube furnace, and the heating mode is started to heat to 1200℃ for high temperature reduction treatment for 1 h, and then cooled to room temperature. The reduction furnace slag and the fumes on the quartz filter screen are collected;

[0062] S3, the reduction furnace slag in step S2 is crushed, and then leached with 20% sulfuric acid by mass fraction at 95℃ for 1 h under the condition of liquid-solid ratio of 5 mL / g. The acid leaching slag is obtained by sulfuric acid leaching and filtration, and is finely ground to a particle size of more than 98% passing through a 320 mesh screen;

[0063] S4, 25 g of the acid leaching slag obtained in step S3 is used as sulfidation agent B, and is fully mixed with 50 g of white tungsten slag powder and 5 g of carbon particles. The high temperature reduction treatment of step S2 and the sulfuric acid leaching treatment of step S3 are repeated for 3 times, and then a high temperature reduction treatment is further carried out (a total of 5 high temperature reduction treatments are carried out in this example) to obtain tungsten-enriched sulfidation slag;

[0064] S5, 5 g of the tungsten-enriched sulfidation slag obtained in step S4 is uniformly stirred with 10 g of sodium hydroxide and then placed in a crucible for calcination at 700℃ for 2 h. The calcination product is ground and then immersed in water at 90℃ for 4 h to obtain a sodium tungstate solution. The filtrate is evaporated and crystallized to obtain sodium tungstate crystals, thereby completing the recovery of valuable metals tungsten and tin from tungsten slag.

[0065] The obtained valuable metal-enriched fumes are analyzed, and the volatilization rate of tin is calculated to be 96.79% by ICP-AES test, and the recovery rate is high. 0.54 g of sodium tungstate is collected from 5 g of enrichment slag, and the average grade of sodium tungstate is 90.05%.

Claims

1. A method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag, characterized in that... The method for recycling valuable metals tungsten and tin is implemented according to the following steps: S1. Thoroughly mix the finely ground and dried tungsten slag powder with reducing agent and sulfiding agent A to obtain a slag-agent mixture; S2. Place the slag-agent mixture from step S1 into the heating zone of the tubular furnace, place the quartz filter screen at the condensing end of the tubular furnace, start the heating mode, heat to 800℃~1200℃ for high-temperature reduction treatment, cool to room temperature, and collect the reduction slag and tin-containing dust on the quartz filter screen. S3. Take the reducing slag from step S2, crush it, and then perform sulfuric acid leaching treatment. The sulfuric acid leaching and filtration process yields acid leaching residue. S4. The acid leaching residue obtained in step S3 is used as sulfiding agent B, and then fully mixed with tungsten slag powder and reducing agent. The mass ratio of sulfiding agent B to tungsten slag is (1~2):(1~2). The high temperature reduction treatment in step S2 and the sulfuric acid leaching treatment in step S3 are repeated multiple times. Finally, a high temperature reduction treatment is performed to obtain tungsten-enriched sulfided residue. S5. After the tungsten-enriched sulfide slag obtained in step S4 is stirred evenly with sodium hydroxide, it is placed in a crucible and roasted at 700°C. The roasted product is filtered after being soaked in water to obtain a sodium tungstate solution. The filtrate is evaporated and crystallized to obtain sodium tungstate crystals, thereby completing the recovery of valuable metals tungsten and tin from tungsten slag. The reducing agent is carbon granules, carbon powder or activated carbon, and the sulfiding agent A is calcium sulfate; In step S3, during the sulfuric acid leaching process, the reducing residue and sulfuric acid with a mass percentage of 20% are leached at a liquid-to-solid ratio of 5-15 mL / g, a leaching temperature of 60-95℃, and a leaching time of 1-4 h.

2. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 1, characterized in that... The particle size of the finely ground tungsten slag powder in step S1 is 1–10 μm.

3. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 1, characterized in that... In step S1, the tungsten slag powder contains Sn at a mass fraction of 0.5%–1.5%, W at a mass fraction of 1%–5%, Ca at a mass fraction of 10%–40%, Fe at a mass fraction of 10%–30%, Mn at a mass fraction of 5%–15%, Si at a mass fraction of 5%–10%, Nb at a mass fraction of 0.5%–2%, and Ta at a mass fraction of 1%–5%.

4. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 1, characterized in that... In step S1, the mass ratio of tungsten slag powder to reducing agent is (1-20):

1.

5. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 4, characterized in that... In step S1, the mass ratio of tungsten slag powder to sulfiding agent A is 100:(4-15).

6. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 1, characterized in that... The high-temperature reduction treatment time in step S2 is 1 to 3 hours.

7. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 1, characterized in that... In step S5, the mass ratio of tungsten-enriched acid leaching residue to sodium hydroxide is 1:(1.1~3), and it is calcined at 700℃ for 2 hours.

8. The method for recovering valuable metals tungsten and tin from hazardous waste tungsten slag according to claim 1, characterized in that... In step S5, the water immersion temperature is 90℃ and the immersion time is 4 hours.

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