A method for immobilizing arsenic using copper slag

Abstract

This invention discloses a method for solidifying arsenic using copper slag. The method involves adding arsenic-containing substances to copper slag, mixing it thoroughly, adding a sulfuric acid solution with a mass concentration of 10-25%, stirring evenly at room temperature, molding, demolding, and curing to achieve the purpose of solidifying arsenic. This invention utilizes the chemical reaction between copper slag and sulfuric acid solution to harden the material, thereby generating strength. When used as a casting material, it not only has the characteristics of fast setting time, good stability, and good durability, but also has excellent adhesion, realizing the comprehensive utilization of industrial waste.

Description

Technical Field

[0001] This invention relates to a method for solidifying arsenic using copper slag, belonging to the field of solid waste and arsenic pollution control technology. Background Technology

[0002] Arsenic, as a metalloid, poses a global environmental and health problem due to its pollution and toxic effects. Against this backdrop, solidification / stabilization technology has been widely researched and applied. This technology, by adding a solidification substrate, firmly fixes or encapsulates arsenic within a stable matrix, thereby reducing the risk of its migration into the environment.

[0003] Copper plays a crucial role in electrical, mechanical, construction, and defense industries due to its excellent electrical, thermal, and ductile properties. Currently, copper smelting is primarily done through pyrometallurgy, accounting for approximately 85% of production; while hydrometallurgy is mostly used to process low-grade ores or secondary resources. Long-term storage of copper slag not only occupies land, but improper storage can also lead to the release and migration of harmful elements, polluting soil and groundwater, causing serious environmental damage.

[0004] Among chemically bonded materials, phosphate systems are among the most extensively studied and have relatively mature processing techniques. These materials are typically prepared from phosphoric acid or acid phosphates with magnesium oxide powder, retarders, and admixtures. When these components are mixed in an aqueous medium, a rapid bonding reaction occurs, forming a dense, ceramic-like structure. This structure not only exhibits high early strength and rapid setting but also demonstrates excellent properties in terms of resistance to salt corrosion, freeze-thaw cycles, wear, and acid corrosion.

[0005] In practical applications of chemically bonded materials for arsenic fixation, key challenges include low long-term stability, poor environmental adaptability, and uneconomical processing. Specifically, traditional cement-based solidified materials are susceptible to damage in highly alkaline environments due to their porous structure, leading to secondary arsenic release. Novel iron-based materials are prone to competition from coexisting ions, resulting in significant pH fluctuations in arsenic fixation efficiency, and the materials themselves may experience performance degradation due to phase transitions. Furthermore, existing systems lack sufficient capacity to fix highly toxic and easily migrating trivalent arsenic, and their long-term reliability in complex real-world environments has not been fully proven. In addition, most technologies are costly and struggle to synergistically achieve arsenic stabilization and product resource utilization, hindering their large-scale engineering application. Summary of the Invention

[0006] This invention provides a method for solidifying arsenic using copper slag. The method involves adding arsenic-containing substances to copper slag, mixing it thoroughly, adding a sulfuric acid solution with a mass concentration of 10-25%, stirring evenly at room temperature, casting it into shape, demolding it, and then curing it to achieve the purpose of solidifying arsenic.

[0007] The copper slag is the main solid waste generated during the copper pyrometallurgical process. The copper slag is ground to a particle size that passes through a 120-mesh sieve and the residue on the sieve is no more than 5%.

[0008] The arsenic-containing substance is an arsenic-containing reagent or arsenic-containing pollutant. The mass ratio of copper slag to arsenic-containing substance is 1:0.03-1:0.1, and the amount of sulfuric acid solution added is 30-40% of the mass of copper slag.

[0009] Fe in the method of this invention 2+ Fe 3+ These can react with arsenate ions to form insoluble compounds (such as FeHAsO4, Fe4As2O4). 11 (Fe3AsO7), further solidifying arsenic in the crystal lattice, thereby reducing the toxic leaching of arsenic.

[0010] Advantages and positive effects of the present invention: (1) The main raw material used in this invention is copper slag, which greatly reduces the production cost. In addition, copper slag is a waste material and can only be simply piled up. The copper slag and sulfuric acid can effectively solidify / stabilize arsenic, which can realize the comprehensive utilization of solid waste and the treatment of pollution with waste. (2) This invention utilizes the chemical reaction between copper slag and sulfuric acid solution to harden the material, thereby generating strength. When used as a casting material, it not only has the characteristics of fast setting time, good stability and good durability, but also has good adhesion, realizing the comprehensive utilization of industrial waste. Attached Figure Description

[0011] Figure 1 XRD pattern of copper slag; Figure 2 The image shows the XRD pattern of the solidified arsenic product in Example 1. Detailed Implementation

[0012] The present invention will be further described in detail below with reference to examples, but the scope of protection of the present invention is not limited to the content described therein; The main components of the copper slag used in the following examples are Fe2O3 63.99%, SiO2 20.22%, Al2O3 3.42%, CaO 2.24%, ZnO 3.04%, SO3 1.76% ( Figure 1 ); Example 1: Method for solidifying arsenic using copper slag 1. 100g copper slag, 3g sodium arsenate, 36.05g sulfuric acid solution with a mass concentration of 20%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 3. Add sodium arsenate to copper slag powder, mix well, then add sulfuric acid solution, stir evenly at room temperature, and pour into molds. Demold after 12 hours, and test its mechanical properties after curing in a 45℃ oven for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 1.4, 2.9, and 4.7 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 1.116, 0.698, and 0.454 mg / L, respectively. XRD analysis of the material yields the following results: Figure 2 As shown in the figure, the material contains FeHAsO4 and Fe4As2O. 11 mineral phases.

[0013] Example 2: Method for solidifying arsenic using copper slag 1. 100g copper slag, 5g sodium arsenate, 36.75g sulfuric acid with a mass concentration of 20%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 2. Add sodium arsenate to copper slag powder, mix well, add sulfuric acid solution, stir evenly at room temperature, and then cast into molds. Demold after 12 hours, and test its mechanical properties after curing in an oven at 45℃ for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 1.2, 2.1, and 3.4 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 1.849, 1.189, and 0.721 mg / L, respectively.

[0014] Example 3: Method for solidifying arsenic using copper slag 1. 100g copper slag, 8g sodium arsenate, 37.8g sulfuric acid with a mass concentration of 20%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 2. Add sodium arsenate to copper slag powder, mix well, add sulfuric acid solution, stir evenly at room temperature, and then cast into molds. Demold after 12 hours, and test its mechanical properties after curing in an oven at 45℃ for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 1.1, 1.7, and 2.7 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 2.803, 2.601, and 2.133 mg / L, respectively.

[0015] Example 4: Method for solidifying arsenic using copper slag 1. 100g copper slag, 10g sodium arsenate, 38.5g sulfuric acid with a mass concentration of 20%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 2. Add sodium arsenate to copper slag powder, mix well, add sulfuric acid solution, stir evenly at room temperature, and then cast into molds. Demold after 12 hours, and test its mechanical properties after curing in an oven at 45℃ for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 1.0, 1.2, and 1.5 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 4.523, 3.516, and 2.863 mg / L, respectively.

[0016] Example 5: Method for solidifying arsenic using copper slag 1. 100 g copper slag, 8 g sodium arsenate, 37.8 g sulfuric acid with a mass concentration of 10%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 2. Add sodium arsenate to copper slag powder, mix well, add sulfuric acid solution, stir evenly at room temperature, and then cast into molds. Demold after 12 hours, and test its mechanical properties after curing in an oven at 45℃ for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 0.5, 0.6, and 1.0 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 1.420, 1.204, and 1.094 mg / L, respectively.

[0017] Example 6: Method for solidifying arsenic using copper slag 1. 100g copper slag, 8g sodium arsenate, 37.8g sulfuric acid with a mass concentration of 15%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 2. Add sodium arsenate to copper slag powder, mix well, add sulfuric acid solution, stir evenly at room temperature, and then cast into molds. Demold after 12 hours, and test its mechanical properties after curing in an oven at 45℃ for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 0.5, 0.6, and 1.1 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 2.734, 2.439, and 2.065 mg / L, respectively.

[0018] Example 7: Method for solidifying arsenic using copper slag 1. 100 g copper slag, 8 g sodium arsenate, 37.8 g sulfuric acid with a mass concentration of 25%. The copper slag should be ground to a particle size of no more than 5% on a 120-mesh sieve. 2. Add sodium arsenate to copper slag powder, mix well, add sulfuric acid solution, stir evenly at room temperature, and then cast into molds. Demold after 12 hours, and test its mechanical properties after curing in an oven at 45℃ for 3d, 7d, and 28d. The compressive strengths at 3d, 7d, and 28d are 1.2, 2.9, and 4.3 MPa, respectively. In the toxicity leaching test, the As leaching concentrations at 3d, 7d, and 28d are 6.579, 4.412, and 3.181 mg / L, respectively.

Claims

1. A method for solidifying arsenic using copper slag, characterized in that: Arsenic-containing substances are added to copper slag, mixed well, and then a sulfuric acid solution with a mass concentration of 10-25% is added. The mixture is stirred evenly at room temperature, molded, demolded, and cured to achieve the purpose of solidifying arsenic.

2. The method for solidifying arsenic using copper slag according to claim 1, characterized in that: Copper slag is ground to a particle size that passes through a 120-mesh sieve with a residue of no more than 5%.

3. The method for solidifying arsenic using copper slag according to claim 1, characterized in that: Arsenic-containing substances are arsenic-containing reagents or arsenic-containing pollutants.

4. The method for solidifying arsenic using copper slag according to claim 1, characterized in that: The mass ratio of copper slag to arsenic-containing substances is 1:0.03-1:0.1, and the amount of sulfuric acid solution added is 30-40% of the mass of copper slag.

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