Treatment method of amorphous arsenic sulfide slag

Abstract

The invention relates to the technical field of environmental protection, and particularly discloses an amorphous arsenic sulfide slag treatment method which comprises the following steps: S1, solid-liquid mixing: mixing arsenic sulfide slag and water according to a solid-liquid ratio of 1: (2-4) to form a suspension; s2, adding a mineralizing agent: adding the mineralizing agent sodium sulfate which is 1-6% of the mass of the arsenic sulfide slag; s3, high-pressure reaction: mixing the solution in the step S1 and the solution in the step S2, transferring the mixed solution into a high-pressure reaction kettle, controlling the temperature to be 100-280 DEG C, and reacting for 30-240 minutes; and S4, post-treatment: filtering the substance after the high-pressure reaction, drying the solid product to obtain a black powder substance, cooling, and sealing and storing with a self-sealing bag. The arsenic sulfide slag is mixed with water to form a suspension, arsenic sulfide slag particles can be uniformly dispersed, the contact area with a mineralizer is increased, the reaction efficiency is improved, excessive water can prevent the arsenic sulfide slag from being sintered or agglomerated at high temperature, a porous structure is maintained, and subsequent solid-liquid separation is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technologies, and particularly to a method for treating amorphous arsenic sulfide slag. Background Art

[0002] Arsenic sulfide slag mainly comes from hazardous waste generated in arsenic-related process in industries such as metallurgy, chemical industry and electronics industry. Its main components are amorphous arsenic sulfides (such as As2S3, As4S4, etc.), which are highly toxic, unstable, and easily oxidized to release arsenic. In addition to the main As-S clusters, there may also be a small amount of oxides, arsenates, etc. Arsenic may form complexes with other metal ions, especially complexes with heavy metal ions, such as arsenic-cadmium complex, arsenic-lead complex, etc. If directly landfilled, it will pollute the environment. Therefore, it is necessary to solidify the arsenic sulfide slag before landfilling.

[0003] Hydrothermal arsenic solidification technology is currently an effective means to solve the potential pollution of arsenic sulfide slag and heavy metal ions. Compared with the traditional method of using lime cement or iron salts to combine arsenic with calcium, iron and aluminum to reduce its toxicity, which uses a large amount of oxidants and stabilizers, resulting in a significant increase in the mass and volume of the slag, the hydrothermal technology can directly convert arsenic sulfide slag into more stable arsenic sulfides or solidify arsenic in the solution into a stable form. Treating arsenic sulfide slag by hydrothermal method can change its phase, microstructure and the form of heavy metal ions, and then the density, form, toxicity and volume of the product will change significantly, making its properties more stable.

[0004] In order to reduce the leaching toxicity of arsenic slag, reduce the solid volume of arsenic slag, and at the same time realize the resource recovery of elemental sulfur, the Chinese invention patent with the authorized publication number of "CN110407179B" discloses a method for synchronous solidification and stabilization of arsenic sulfide slag and sulfur resource recovery. Using the hydrothermal method, by introducing a mixed solution of mineralizing agents aluminum sulfate, sodium sulfate and hydrogen peroxide, adjusting the pH, reacting in a high-pressure reactor, and drying, a yellow solid is obtained as elemental sulfur and a white filter residue is obtained as sodium aluminoarsenate. Sodium aluminoarsenate is a very stable mineral. This method realizes the stabilization disposal of arsenic-containing waste residue in one step and recovers and reuses sulfur resources. Since the arsenic sulfide slag is directly mixed with the mineralizing agent and the composition of the mineralizing agent is less and the water content is insufficient, the mineralizing agent cannot fully contact with the arsenic sulfide slag, and the arsenic sulfide slag is prone to sintering or caking at high temperature, which is not conducive to subsequent solid-liquid separation. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for treating amorphous arsenic sulfide slag to solve the problems of easy secondary pollution and large land occupation area when using inert materials to wrap arsenic sulfide slag for sanitary landfill.

[0006] To solve the above problems, the following technical solutions are provided:

[0007] A method for treating amorphous arsenic sulfide residue, comprising the following steps:

[0008] S1: Solid-liquid mixing: Mix the arsenic sulfide residue with water at a solid-liquid ratio of 1:(2-4) to form a suspension;

[0009] S2: Adding mineralizer: Add sodium sulfate as a mineralizer accounting for 1-6% of the mass of the arsenic sulfide residue;

[0010] S3: High-pressure reaction: Mix the solutions in steps S1 and S2, transfer the mixed solution to a high-pressure reactor, control the temperature at 100-280°C, and react for 30-240 min;

[0011] S4: Post-treatment: Filter the material after the high-pressure reaction, the solid product is dried to obtain a black powder material, and after cooling, it is sealed and stored in a self-sealing bag.

[0012] Preferred solution 1: As a further optimization of the basic solution, the solid-liquid ratio in step S1 is 1:3.

[0013] Preferred solution 2: As a further optimization of preferred solution 1, in step S2, a sodium sulfate solution with a preferably 5% mass fraction is used as the mineralizer.

[0014] Preferred solution 3: As a further optimization of preferred solution 2, in step S3, the preferably temperature is 180°C.

[0015] Preferred solution 4: As a further optimization of preferred solution 3, in step S3, the preferably reaction time is 180 min.

[0016] The beneficial effects of the above technical solutions are as follows:

[0017] 1. Compared with directly mixing the existing arsenic sulfide residue with the mineralizer, in this technical solution, the arsenic sulfide residue first forms a suspension through water mixing, which can evenly disperse the arsenic sulfide residue particles. The suspension can increase the contact area with the mineralizer, improve the reaction efficiency, and the excessive water can prevent the arsenic sulfide residue from sintering or caking at high temperature, maintain the porous structure, and facilitate subsequent solid-liquid separation;

[0018] 2. Through the combined action of high temperature and high pressure with the mineralizer, amorphous arsenic sulfide is converted into stable crystalline minerals;

[0019] 3. The optimized combination of the solid-liquid ratio and reaction parameters can synchronously reduce the arsenic leaching toxicity, moisture content, and increase the bulk density. Description of the drawings

[0020] Figure 1 It is a physical diagram of the arsenic sulfide residue before treatment of the present invention;

[0021] Figure 2 This is the physical diagram after the treatment of arsenic sulfide slag in the present invention. Specific embodiments

[0022] The present invention will be further described below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto.

[0023] The specific operation steps are as follows:

[0024] Embodiment 1

[0025] A method for treating amorphous arsenic sulfide slag, comprising the following steps:

[0026] S1: Solid-liquid mixing: Take 70 g of arsenic sulfide slag (as Figure 1 shown) and mix it with 210 g of water (solid-liquid ratio 1:3);

[0027] S2: Adding mineralizer: Add 0.7 g of ferric sulfate (1% of the slag weight) as the mineralizer;

[0028] S3: High-pressure reaction: Mix the solutions in steps S1 and S2, transfer the mixed solution to a high-pressure reactor, and control the temperature at five temperature gradients of 100 °C, 150 °C, 180 °C, 230 °C, and 280 °C, and react for 30 min respectively;

[0029] S4: Post-treatment: Filter the material after the high-pressure reaction, and the solid product is dried to obtain a black powder material (as Figure 2 shown), and store it sealed in a self-sealing bag after cooling;

[0030] S5: Product detection: Measure the arsenic leaching toxicity, moisture content, and bulk density of the black powder material.

[0031] Embodiment 2

[0032] The difference between Embodiment 2 and Embodiment 1 is that 2.1 g of ferric sulfate (3% of the slag weight) is added, and the reaction time in the autoclave is 70 min.

[0033] Embodiment 3

[0034] The difference between Embodiment 3 and Embodiment 1 is that 2.8 g of ferric sulfate (4% of the slag weight) is added, and the reaction time in the autoclave is 100 min.

[0035] Embodiment 4

[0036] The difference between Embodiment 4 and Embodiment 1 is that 3.5 g of ferric sulfate (5% of the slag weight) is added, and the reaction time in the autoclave is 180 min.

[0037] Embodiment 5

[0038] Example 5 is different from Example 1 in that 4.2 g of ferric sulfate (6% of the slag weight) is added, and the autoclave reaction time is 240 min.

[0039] The detection indexes of the arsenic leaching toxicity of the residues obtained in Examples 1 - 5 (unit: mg / L) are shown in Table 1 below:

[0040]

[0041] The test results of the moisture content (gravimetric method) of the arsenic sulfide slag in Examples 1 - 5 after the reaction is completed at each parameter gradient are shown in Table 2 below:

[0042]

[0043] The bulk density (unit: g / cm 3 ) test results of the arsenic sulfide slag in Examples 1 - 5 after the reaction is completed at each parameter gradient are as follows

[0044] shown in Table 3:

[0045]

[0046] It can be seen from the data in Table 1 that after adding 5% of the mineralizer, at a reaction temperature of 180 °C and a reaction time of 180 min, the lowest arsenic leaching is 4.19 mg / L;

[0047] It can be seen from the data in Table 2 that after adding 5% of the mineralizer, at a temperature of 180 °C and a reaction time of 180 min, the moisture content of the sample is measured to be the lowest, which is 0.23%;

[0048] It can be seen from the data in Table 3 that after adding 5% of the mineralizer, at a temperature of 180 °C and a reaction time of 180 min, the lowest bulk density of the sample is tested, which is 1.26 g / cm 3 .

[0049] The original bulk density of the arsenic sulfide slag is 0.92 g / cm 3 , and the best bulk density after hydrothermal treatment is 1.26 g / cm 3 , so the arsenic sulfide slag can save 26.98% of the storage capacity after being landfilled after hydrothermal treatment; the original moisture content of the arsenic sulfide slag is 55.71% water, and the best moisture content after hydrothermal treatment is 0.24%, so the moisture is reduced by 99%.

[0050] In this solution, water is mixed with the arsenic sulfide slag to form a suspension, which can evenly disperse the arsenic sulfide slag particles, increase the contact area with the mineralizer, and reduce the arsenic leaching toxicity (<5 mg / L, meeting the GB 5085.3 standard), moisture content (<15%) and increase the bulk density after the reaction. It meets the landfill standard and saves landfill space.

[0051] The above are only embodiments of the present invention, and common knowledge such as specific structures and characteristics known in the solutions is not described in detail herein. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A method for treating amorphous arsenic sulfide slag, characterized in that, Including the following steps: S1: Solid-liquid mixing: Mix arsenic sulfide residue with water at a solid-liquid ratio of 1:(2 - 4) to form a suspension; S2: Mineralizer addition: Add sodium sulfate as a mineralizer at 1 - 6% of the mass of the arsenic sulfide residue; S3: High-pressure reaction: Mix the solutions in steps S1 and S2, transfer the mixed solution to a high-pressure reactor, control the temperature at 100 - 280 °C, and react for 30 - 240 min; S4: Post-treatment: Filter the material after the high-pressure reaction, the solid product is dried to obtain a black powder material, and after cooling, it is sealed and stored in a self-sealing bag.

2. The treatment method of an amorphous arsenic sulfide residue according to claim 1, characterized in that: The solid-liquid ratio in step S1 is 1:

3.

3. The treatment method of amorphous arsenic sulfide slag according to claim 2, characterized in that: In step S2, a sodium sulfate solution with a mass fraction of 5% is used as the mineralizer.

4. The treatment method of amorphous arsenic sulfide slag according to claim 3, characterized in that: In step S3, the temperature is 180 °C.

5. The treatment method of amorphous arsenic sulfide residue according to claim 4, characterized in that: The reaction time in step S3 is 180 min.

Images