Method for reducing amount and volume of arsenic sulfide slag in copper smelting

Abstract

The invention provides a copper smelting arsenic sulfide slag decrement and volume reduction method, which comprises the steps of pretreatment, main reaction and post-treatment, and specifically comprises the following steps: adding water into to-be-treated copper smelting arsenic sulfide slag for size mixing to obtain a material a; putting the material a into a high-pressure reaction kettle, controlling the filling rate to be 60-80%, and performing hydrothermal reaction under the conditions that the pressure is 0.6-1.2 MPa and the rotating speed is 400-800r / min to obtain reaction liquid b; and filtering the reaction liquid b to obtain volume-reduced harmless slag.

Description

Technical Field

[0001] The invention belongs to the field of metallurgy and chemical industry, and in particular relates to a method for reducing the amount and volume of copper smelting arsenic sulfide slag. Background Art

[0002] Common treatments for arsenic sulfide slag include solidification treatment technology and encapsulation coating technology. The former uses cement, gypsum, glass and other curing agents and chemicals to achieve the purpose of solidifying arsenic, but the use of a large amount of curing agents increases the weight and volume of the waste; the latter uses a highly complete sealing structure system such as gel materials to further coat the stabilized arsenic-containing solids to ensure that they will not cause secondary pollution to the environment during the landfill process, but the technical cost is high and the operation is complicated. Arsenic sulfide slag has a high arsenic content and can be used to produce arsenic-containing products such as orpiment, arsenic trioxide, and elemental arsenic. However, due to the very limited demand for arsenic consumption, the production of arsenic products is uneconomical and unapplicable, and is usually treated as hazardous solid waste for harmless treatment. Arsenic sulfide slag is fluffy and moist, and the moisture content is still as high as 50~70% after filtration. Storage requires a lot of space, and harmless treatment increases the treatment cost. Therefore, in addition to considering pollution reduction during the treatment of arsenic sulfide slag, volume reduction and quantity reduction are also key issues. Summary of the invention

[0003] The object of the present invention is to provide a method for reducing the amount and volume of copper smelting arsenic sulfide slag.

[0004] The object of the present invention is achieved in that the method for reducing the amount and volume of copper smelting arsenic sulfide slag comprises pretreatment, main reaction and post-treatment steps, specifically comprising: A. Pretreatment: Add water to the copper smelting arsenic sulfide slag to be treated and prepare the slurry to obtain material a; B. Main reaction: Place material a in a high-pressure reactor, control the filling rate to 60-80%, and perform hydrothermal reaction at a pressure of 0.6-1.2 MPa and a rotation speed of 400-800 r / min to obtain reaction solution b; By synergistically controlling appropriate technical conditions, the nano-scale fluffy arsenic sulfide slag with a water content of 50~70% has its grains grown, the crystallinity greatly improved, and the microstructure and morphology changed under suitable mineralization technical conditions. Therefore, the water absorption rate is greatly reduced, and the density and stability are greatly improved, thereby achieving reduction in amount and volume and reducing leaching toxicity.

[0005] C. Post-treatment: The reaction solution b was filtered to obtain harmless slag with reduced volume. The harmless slag was tested for arsenic, selenium, fluoride, cyanide and other 15 items before and after treatment according to the detection methods of "Determination of mercury, arsenic, selenium, bismuth and antimony in solid waste", "Determination of 22 metal elements in solid waste" and "Determination of fluoride in solid waste". After treatment, arsenic was reduced from 330-400 mg / L to 120-135 mg / L, and the toxic leaching indicators of the remaining elements were reduced to meet the concentration limits of the leaching toxicity identification standard of the "Identification Standard for Hazardous Waste Identification" (GB 5085.3-2007).

[0006] The specific operations are as follows: (1) arsenic sulfide slag is slurried at a solid-liquid ratio of 1:1 to 1:10, the pH value is adjusted to 2 to 5, a stirring paddle is started to stir evenly, and the mixture is transferred to a high-pressure reactor for hydrothermal reaction; (2) The filling rate is 60-80%, the reaction temperature is controlled at 160-200°C, the rotation speed is 400-800 r / min, the pressure is 0.6-1.2 MPa, the reaction time is 2-5 h, and cold water is passed through for cooling after the reaction is completed; (3) Take out the slurry and filter it with a vacuum filter. Weigh the mass of the slag sample. Calculate the reduction of the wet weight of the slag after treatment compared with the wet weight of the slag before treatment, and calculate the volume reduction with the aid of the stockpile density.

[0007] In recent years, attempts have been made to treat arsenic sulfide slag with hydrothermal arsenic fixation. This method uses hydrothermal technology to chemically react with arsenic-containing aqueous solution under high temperature and high pressure to generate highly stable calcium arsenate or other complexes to achieve the effect of arsenic fixation. This method has the advantages of short process flow and good arsenic precipitation effect. The generated arsenic fixation minerals can remain stable in a wide pH range and under strong reducing conditions, and are not easy to release arsenic again. Its stabilization mechanism can be summarized as follows: after hydrothermal treatment, arsenic sulfide gradually grows from aggregates of nanoparticles into large spherical particles, and the crystallinity is greatly improved, thereby reducing internal defects, reducing the leaching concentration of arsenic, and improving the stability of arsenic sulfide slag. This method usually adds oxidants and stabilizers such as aluminum salts, sodium salts, and iron salts to generate compounds such as sodium arsenic alum and scorodite. Its reaction mechanism is: hydrogen peroxide decomposes into oxygen and water at high temperature, and arsenic sulfide slag is oxidized and dissolved at high temperature to generate sulfur and arsenate ions. Under the action of hydrothermal, AsO4 3- It reacts with Fe(III) to form scorodite with a particle size of about 25μm, and replaces the sulfate group in sodium alumite NaAl3(SO4)2(OH)6 to form sodium arsenic alumite.

[0008] The method of the present invention treats arsenic sulfide slag, and by reasonably controlling the liquid-solid ratio, pH value, reaction temperature, rotation speed, reaction time, and reaction pressure, no oxidant and stabilizer need to be added, and significant reduction in quantity and volume can be achieved, so that the arsenic sulfide slag tends to be stable, and the leaching toxicity of arsenic is reduced. The method has a simple process flow, does not add wastewater, waste gas, and waste residue in the whole process, and has the characteristics of cleanliness, high efficiency, and low operating cost.

[0009] The present invention uses a pressure autoclave to directly achieve the transformation of the microstructure and appearance of amorphous arsenic sulfide slag under high temperature and high pressure without adding stabilizers and catalysts, making it stable, and achieving a volume reduction of 70-85% and a volume reduction of 60-76% in a short process, low cost and high efficiency. The toxicity of arsenic sulfide slag is also reduced, and the As content of the toxic leaching solution is reduced from 330-400 mg / L to 120-135 mg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The XRD test of arsenic sulfide slag before treatment showed only a small amount of sodium bisulfate peak, and As2S3 was an unstable amorphous substance; Figure 2 The arsenic sulfide slag treated by the present invention is transformed into a crystal form, showing a more stable As2S3 quasicrystal phase. DETAILED DESCRIPTION

[0011] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0012] The method for reducing the amount and volume of copper smelting arsenic sulfide slag of the present invention comprises pretreatment, main reaction and post-treatment steps, specifically comprising: A. Pretreatment: Add water to the copper smelting arsenic sulfide slag to be treated and prepare the slurry to obtain material a; B. Main reaction: Place material a in a high-pressure reactor, control the filling rate to 60-80%, and perform hydrothermal reaction at a pressure of 0.6-1.2 MPa and a rotation speed of 400-800 r / min to obtain reaction solution b; C. Post-treatment: The reaction solution b is filtered to obtain harmless slag with reduced volume and quantity.

[0013] In step A, the solid-liquid mass volume ratio of the copper smelting arsenic sulfide slag to be treated and water is 1: (1-10) g / ml.

[0014] The pH value of material a in step A is 2~5.

[0015] The temperature of the hydrothermal reaction in step B is 160-200°C.

[0016] The time of the hydrothermal reaction described in step B is 2 to 5 hours.

[0017] The filtration described in step C is suction filtration, centrifugal filtration or pressure filtration.

[0018] The composition of the copper smelting arsenic sulfide slag is shown in the following table: .

[0019] The present invention is further described below with specific implementation cases: Example 1 The raw material is arsenic sulfide slag from a company in Yuxi, Yunnan, with a stockpile density of 0.59 g / cm 3 , the toxic leaching solution test results showed that As was 365 mg / L.

[0020] According to the mass volume ratio of arsenic sulfide slag to water of 1g:1ml, 600g of arsenic sulfide slag was mixed with 600ml of water for slurry preparation. After stirring evenly, it was placed in a 2L autoclave for hydrothermal reaction. The hydrothermal reaction parameters were set as follows: reaction temperature 170°C, rotation speed 500r / min, reaction time 2h, pressure control at 0.7~0.8MPa, and filling rate 60%. After the reaction was completed, cold water was passed to cool to room temperature, and then filtered using a suction filtration device. The wet slag weight was measured to be 193.24g and the stockpile density was 0.87g / cm 3 , the toxic leaching leachate test result As is 137mg / L. After calculation, the reduction, volume reduction and arsenic toxicity leaching leachate test results after treatment by this method are as follows: Weight reduction: (600g-193.24g) / 600g×100%=67.79% Reduction: 1-[(193.24÷0.87)÷(600÷0.59)]=78.16% Toxicity: The toxic leaching solution test results showed that As was reduced from 365 mg / L to 137 mg / L, and the leaching toxicity was reduced to 36.53% of the original.

[0021] Example 2 The raw material is arsenic sulfide slag from a company in Chuxiong, Yunnan, with a stockpile density of 0.57 g / cm 3 , the toxic leaching solution test results showed that As was 345 mg / L.

[0022] According to the mass volume ratio of arsenic sulfide slag to water of 1g:2ml, 1000g of arsenic sulfide slag was mixed with 2000ml of water for slurry preparation. After stirring evenly, it was placed in a 5L autoclave for hydrothermal reaction. The hydrothermal reaction parameters were set as follows: reaction temperature 180°C, rotation speed 600r / min, reaction time 2.5h, pressure control at 0.8~0.9MPa, and filling rate 60%. After the reaction was completed, cold water was passed to cool to room temperature, and then filtered using a filter press. The wet slag weight was measured to be 345.37g and the stockpile density was 0.92g / cm 3 , the toxic leaching leachate test result As is 126mg / L. After calculation, the reduction, volume reduction and arsenic toxicity leaching leachate test results after treatment by this method are as follows: Weight reduction: (1000g-345.37g) / 1000g×100%=65.46% Reduction: 1-[(345.37÷0.92)÷(1000÷0.57)]=78.60% Toxicity: The toxicity leaching solution test results showed that As was reduced from 345 mg / L to 126 mg / L, and the leaching toxicity was reduced to 36.52% of the original.

[0023] Example 3 The raw material is arsenic sulfide slag from a company in Yuxi, Yunnan, with a stockpile density of 0.54 g / cm 3 , the toxic leaching solution test results showed that As was 388 mg / L.

[0024] According to the mass volume ratio of arsenic sulfide slag to water of 1g:3ml, 350g of arsenic sulfide slag was mixed with 1050ml of water for slurry preparation. After stirring evenly, it was placed in a 2L autoclave for hydrothermal reaction. The hydrothermal reaction parameters were set as follows: reaction temperature 190°C, rotation speed 600r / min, reaction time 3h, pressure control at 0.9~1.0MPa, and filling rate 70%. After the reaction was completed, cold water was passed through to cool to room temperature, and then filtered using a filter press. The wet slag weight was measured to be 109.03g and the stock density was 0.87g / cm 3 , the toxic leaching leachate test result As is 122mg / L. After calculation, the reduction, volume reduction and arsenic toxicity leaching leachate test results after treatment by this method are as follows: Weight reduction: (350g-109.03g) / 350g×100%=68.85% Reduction: 1-[(109.03÷0.87)÷(350÷0.54)]=80.66% Toxicity: The toxic leaching solution test results showed that As was reduced from 388 mg / L to 122 mg / L, and the leaching toxicity was reduced to 31.44% of the original.

Claims

1. A method for reducing the amount and volume of copper smelting arsenic sulfide slag, characterized in that: The method for reducing the amount and volume of copper smelting arsenic sulfide slag includes pretreatment, main reaction and post-treatment steps, specifically including: A. Pretreatment: Add water to the copper smelting arsenic sulfide slag to be treated and prepare the slurry to obtain material a; B. Main reaction: Place material a in a high-pressure reactor, control the filling rate to 60-80%, and perform hydrothermal reaction at a pressure of 0.6-1.2 MPa and a rotation speed of 400-800 r / min to obtain reaction solution b; C. Post-treatment: The reaction solution b is filtered to obtain harmless slag with reduced volume and quantity.

2. The method for reducing the amount and volume of copper smelting arsenic sulfide slag according to claim 1, characterized in that: In step A, the solid-liquid mass volume ratio of the copper smelting arsenic sulfide slag to be treated and water is 1: (1-10) g / ml.

3. The method for reducing the amount and volume of copper smelting arsenic sulfide slag according to claim 1, characterized in that: The pH value of material a in step A is 2~5.

4. The method for reducing the amount and volume of copper smelting arsenic sulfide slag according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step B is 160-200°C.

5. The method for reducing the amount and volume of copper smelting arsenic sulfide slag according to claim 1, characterized in that: The time of the hydrothermal reaction described in step B is 2 to 5 hours.

6. The method for reducing the amount and volume of copper smelting arsenic sulfide slag according to claim 1, characterized in that: The filtration described in step C is suction filtration, centrifugal filtration or pressure filtration.

7. The method for reducing the amount and volume of copper smelting arsenic sulfide slag according to claim 1, characterized in that: The composition of the copper smelting arsenic sulfide slag is shown in the following table: 。

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