A solidification treatment agent for electrolytic cell overhaul slag and a resource treatment method

Abstract

The application belongs to the technical field of solid waste resource processing, and specifically discloses a solidification treatment agent for electrolytic cell overhaul slag and a resource processing method. The solidification treatment agent is composed of calcium chloride, calcium hypochlorite, cement and gypsum in a mass ratio of (1-1.2):(5-6):(2-3):(1-2). The processing method comprises the following steps: grinding and grading and sorting electrolytic cell overhaul slag to obtain carbon-rich material and electrolyte-fire-resistant material mixture; adding water to the solidification treatment agent to prepare a suspension, adding the mixture into the suspension at 45-61% of the mass of the overhaul slag, and stirring and reacting to realize harmless solidification. The solidification treatment agent can comprehensively and harmlessly dispose of fluorides and cyanides in the overhaul slag, has a long-lasting solidification and stabilization effect, and is low in cost. The processing method realizes resource recycling of carbonaceous materials through grading and sorting, and the remaining mixture is safe and stable after being solidified by the solidification treatment agent. The process is simple and easy to implement industrially, and gives consideration to resource recycling, harmless disposal and economy, and is suitable for large-scale safe disposal and resource utilization of electrolytic cell overhaul slag.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a solidification treatment agent and resource utilization method for electrolytic cell overhaul residue. Background Technology

[0002] Electrolytic cell overhaul slag is a hazardous solid waste generated during the periodic replacement of the lining material of electrolytic cells in a high-temperature, highly corrosive environment during the electrolytic aluminum production process. Its main components include ineffective cathode carbon blocks, damaged refractory materials, and highly hazardous pollutants, primarily soluble fluoride salts and cyanides. Fluorides are highly corrosive and have strong environmental mobility, easily causing water pollution and ecological damage; cyanides are extremely toxic, posing a serious threat to human health. Given its significant environmental risks, this waste slag has been explicitly listed by the state as a key non-ferrous metal smelting waste requiring special control in the "Hazardous Waste List" (HW48 category). Its safe disposal is a critical environmental challenge that the electrolytic aluminum industry must address to ensure sustainable development.

[0003] Currently, while treatment technologies for this type of waste have made some progress, they all have significant limitations. Cement kiln co-processing technology can decompose some organic matter using a high-temperature environment and integrate the residue into cement clinker, but its solidification rate for fluorides is greatly affected by raw material compatibility, its stability is insufficient, and its effectiveness in completely decomposing cyanides is limited. Wet treatment processes achieve pollutant separation through strong acid or strong alkali leaching, but suffer from severe equipment corrosion, complex process flows, and the potential generation of high-concentration secondary wastewater. High-temperature roasting technology can achieve thermal decomposition of pollutants, but it consumes a lot of energy and may lead to the secondary release of pollutants such as fluorine and cyanide due to volatilization or incomplete reactions, making its economic efficiency and environmental safety unsatisfactory.

[0004] In summary, existing technologies struggle to achieve the simultaneous, efficient stabilization and detoxification of characteristic pollutants—fluorides and cyanides—in electrolytic cell overhaul slag while remaining economically feasible, process-simplified, and environmentally friendly. In particular, existing processes generally fail to adequately address the effective separation and resource recovery of valuable components (such as carbon materials and metals) from the waste slag while achieving detoxification. Therefore, developing a comprehensive treatment process capable of synergistically solidifying fluorides, oxidatively degrading cyanides, and enabling the separate recovery of each component has become a pressing technical challenge in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a solidification treatment agent and a resource utilization method for electrolytic cell overhaul residue.

[0006] The present invention provides a curing agent for the overhaul residue of an electrolytic cell. The curing agent comprises calcium chloride, calcium hypochlorite, cement and gypsum, wherein the mass ratio of calcium chloride, calcium hypochlorite, cement and gypsum is (1~1.2):(5~6):(2~3):(1~2).

[0007] The solidifying agent for electrolytic cell overhaul slag of this invention uses calcium chloride, calcium hypochlorite, cement, and gypsum as core raw and auxiliary materials, supplemented with gypsum. Through synergistic and complementary effects, the components achieve efficient and harmless treatment of fluorides and cyanides in the electrolytic cell overhaul slag, while also controlling costs, thus improving treatment effectiveness and practicality. Specifically, calcium chloride, through the chemical reaction CaCl2 + 2NaF → CaF2↓ + 2NaCl, converts fluorides in the overhaul slag into insoluble calcium fluoride precipitate, completely blocking the migration and pollution pathways of fluorides; calcium hypochlorite simultaneously passes through CN... - + ClO - → N2 + CO2 + Cl - Oxidation decomposes cyanide, converting harmful cyanide ions into harmless products. After calcium chloride and calcium hypochlorite complete the conversion of harmful components, cement generates CSH gel and other products through the C3S + H2O → CSH gel + Ca(OH)2 hydration reaction. This tightly binds the overhaul slag particles, the harmless precipitates generated by the two reactions, and the unreacted components, forming a dense solidified body. This further encapsulates and fixes the harmful component residues, preventing secondary leaching and migration, and ensuring the mechanical stability of the solidified body, thus achieving long-term harmless treatment. Gypsum, as an auxiliary component, contains effective calcium that can partially replace calcium chloride, assisting in the fluoride removal reaction and reducing the amount of calcium chloride used. At the same time, its curing properties can partially replace cement, assisting in the formation of the solidified body. This curing agent achieves comprehensive harmless treatment of fluorides and cyanides in overhaul slag through the synergistic and complementary interaction of four components: calcium chloride, calcium hypochlorite, cement, and gypsum. It also ensures the long-term effectiveness of the treatment through curing and optimizes the components to control costs. Ultimately, it achieves the goal of harmless, long-term, and low-cost treatment of electrolytic cell overhaul slag.

[0008] Preferably, the mass ratio of calcium chloride, calcium hypochlorite, cement, and gypsum is 1:5.5:2:1.5.

[0009] Furthermore, the cement is ordinary Portland cement with a grade of not less than 42.5; the gypsum is at least one of desulfurized gypsum, natural gypsum, or building gypsum.

[0010] Furthermore, the mass ratio of the curing agent component to water is 1:(1~1.5), and the amount of the curing agent mixed suspension added accounts for 45~61% of the mass of the electrolytic cell overhaul residue.

[0011] Another aspect of the present invention provides a method for the resource utilization of electrolytic cell overhaul residue, comprising the following steps:

[0012] S1 involves crushing and classifying the overhaul residue from the electrolytic cell to obtain carbonaceous enriched material and electrolyte-refractory material mixture, respectively.

[0013] S2 Preparation of curing agent: Add the curing agent to water and mix evenly to form a curing agent suspension;

[0014] S3. Add the curing agent mixed suspension to the electrolyte-refractory material mixture at 45-61% of the mass of the electrolytic cell overhaul residue, stir, react, and obtain the treated electrolytic cell overhaul residue.

[0015] This invention relates to a method for the resource-based treatment of electrolytic cell overhaul slag. Through a decomposition and sorting process involving grinding and grading, the slag is precisely separated into carbonaceous enriched material and an electrolyte-refractory material mixture. This allows for the separate resource utilization of the two components: the carbonaceous enriched material can be recycled as a secondary energy source or raw material, while the electrolyte-refractory material mixture is treated by adding a scientifically proportioned solidifying agent to form a suspension, followed by stirring and reaction to achieve harmless treatment. This method effectively taps into the resource potential of overhaul slag, avoids resource waste, and achieves efficient and harmless disposal of the slag through a simple and easy-to-operate process, thus balancing resource utilization, environmental protection, and practicality.

[0016] Furthermore, the particle size of the crushed electrolytic cell overhaul slag is ≤10mm. This prevents the fluorine and cyanide components encapsulated in large lining blocks from failing to fully react and be removed.

[0017] Furthermore, the grading and sorting includes magnetic separation and air separation; the magnetic separation uses magnets to adsorb and remove metal debris from the overhaul slag of the electrolytic cell; the air separation uses different air forces to separate the carbonaceous enrichment material from the electrolyte-refractory material. The crushed coarse material is subjected to magnetic separation to separate water-contaminated debris such as iron and aluminum, which are then recycled for use as metallurgical auxiliary materials, and to remove metal impurities that could interfere with subsequent processes. Based on the density difference between the carbonaceous enrichment material and the electrolyte, a mixture of carbonaceous enrichment material and electrolyte-refractory material is separated, laying the foundation for their separate utilization in the future.

[0018] Furthermore, the carbonaceous enriched material is acid-washed and then calcined to obtain modified carbonaceous material.

[0019] Furthermore, the pickling uses 3-5% dilute hydrochloric acid; the calcination is carried out under inert gas protection at a temperature of 800-900℃ for 2-3 hours.

[0020] In some embodiments of the present invention, the carbonaceous enriched material is fed into an acid washing tank, dilute hydrochloric acid is added, and the mixture is stirred at room temperature for 30-60 minutes to remove surface-adhered fluoride salts and impurities. The mixture is then filtered and washed until neutral to obtain purified carbon. The purified carbon is then sent to a calcining furnace, and under inert gas protection, the calcination temperature is controlled at 800-900°C for 2-3 hours to remove residual moisture and trace impurities, increasing the graphitization of the carbon to over 90%, thus obtaining modified carbon. The modified carbon can be directly reused in the production of cathode carbon blocks for electrolytic aluminum, or it can be used to process graphite products.

[0021] Furthermore, the electrolytic cell overhaul slag processed in step S3 can be directly used as refractory brick material.

[0022] In some embodiments of the present invention, the electrolytic cell overhaul slag processed in step S3 is directly sent to a pressing and molding equipment to be pressed into standard brick blanks, and oxidized at room temperature for 36 hours to obtain refractory bricks.

[0023] The beneficial effects of this invention are:

[0024] 1) Simultaneous and Efficient Detoxification of Pollutants: The solidification agent provided by this invention, through the synergistic effect of calcium chloride, calcium hypochlorite, cement, and gypsum, can simultaneously achieve efficient stabilization treatment of fluorides and cyanides in the overhaul residue of electrolytic cells. Specifically, fluorides are removed by conversion into insoluble calcium fluoride precipitates (removal rate ≥85%), and cyanides are removed by oxidative decomposition into harmless products (removal rate ≥99%). The leaching toxicity after treatment meets the "Standard for Pollution Control of Hazardous Waste Landfill" (GB 18598-2019), achieving safe disposal of hazardous waste.

[0025] 2) Low processing cost and environmental benefits: As an industrial solid waste, gypsum partially replaces calcium chloride and cement, which not only reduces raw material costs (by about 40% compared to traditional methods) but also realizes the resource utilization of industrial by-products, resulting in good environmental benefits. The processing cycle is shortened to 3-5 days, improving overall processing efficiency and economy.

[0026] 3) Segmented Resource Utilization for Full Component Recycling: Through grading and sorting processes such as crushing, magnetic separation, and air classification, overhaul slag is separated into metal scrap, carbonaceous enriched material, and electrolyte-refractory material mixture. The carbonaceous enriched material, after acid washing and calcination, yields modified carbon material, which can be reused in cathode carbon blocks or graphite products. The electrolyte-refractory material mixture, after treatment with a curing agent, can be directly used to prepare refractory bricks. This achieves full component resource utilization of overhaul slag.

[0027] 4) Excellent properties of the cured body: The cured body possesses good mechanical properties and low permeability, with an unconfined compressive strength of ≥0.5MPa at 7 days, a compressive strength of ≥2.0MPa at 28 days, and a permeability coefficient of ≤10.-7 The speed of cm / s meets the basic performance requirements for refractory bricks and other building materials, and has good long-term stability, effectively preventing the secondary release of pollutants. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the resource utilization process of electrolytic cell overhaul residue according to the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments thereof. 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 protection scope of the present invention.

[0030] Example 1

[0031] This embodiment provides a solidification treatment agent for electrolytic cell overhaul residue, which includes 1 kg of calcium chloride, 5 kg of calcium hypochlorite, 2 kg of cement, and 1 kg of desulfurized gypsum.

[0032] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0033] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0034] S2 Curing Agent Preparation: Mix the above curing agent components, add 9 kg of deionized water, and stir to form a uniform curing agent suspension;

[0035] S3 Curing treatment: Add 5 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0036] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0037] Example 2

[0038] This embodiment provides a curing agent for the overhaul residue of an electrolytic cell, which includes 1.2 kg of calcium chloride, 6 kg of calcium hypochlorite, 3 kg of cement, and 2 kg of natural gypsum.

[0039] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0040] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0041] S2 Curing Agent Preparation: Mix the above curing agent components, add 18.3 kg of deionized water, and stir to form a uniform curing agent suspension;

[0042] S3 Curing treatment: Add 6.1 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0043] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0044] Example 3

[0045] This embodiment provides a curing agent for the overhaul residue of an electrolytic cell, which includes 1 kg of calcium chloride, 5.5 kg of calcium hypochlorite, 2 kg of cement, and 1.5 kg of building gypsum.

[0046] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0047] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0048] S2 Curing Agent Preparation: Mix the above curing agent components, add 12kg of deionized water, and stir to form a uniform curing agent suspension;

[0049] S3 Curing treatment: Add 4.5 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0050] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0051] Example 4

[0052] This embodiment provides a solidification treatment agent for electrolytic cell overhaul residue, which includes 1.1 kg of calcium chloride, 5.8 kg of calcium hypochlorite, 2.5 kg of cement, and 1.8 kg of desulfurized gypsum.

[0053] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0054] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0055] S2 Curing Agent Preparation: Mix the above curing agent components, add 14 kg of deionized water, and stir to form a uniform curing agent suspension;

[0056] S3 Curing treatment: Add 5.5 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0057] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0058] Comparative Example 1

[0059] This comparative example provides a curing agent for the overhaul residue of an electrolytic cell, which includes 5 kg of calcium hypochlorite, 2 kg of cement, and 1 kg of desulfurized gypsum.

[0060] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0061] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0062] S2 Curing Agent Preparation: Mix the above curing agent components, add 8 kg of deionized water, and stir to form a uniform curing agent suspension;

[0063] S3 Curing treatment: Add 5 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0064] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0065] Comparative Example 2

[0066] This comparative example provides a solidification treatment agent for the overhaul residue of an electrolytic cell, which includes 1 kg of calcium chloride, 2 kg of cement, and 1 kg of desulfurized gypsum.

[0067] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0068] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0069] S2 Curing Agent Preparation: Mix the above curing agent components, add 4 kg of deionized water, and stir to form a uniform curing agent suspension;

[0070] S3 Curing treatment: Add 5 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0071] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0072] Comparative Example 3

[0073] This comparative example provides a solidification treatment agent for electrolytic cell overhaul residue, which includes 1 kg of calcium chloride, 5 kg of calcium hypochlorite, and 2 kg of cement.

[0074] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0075] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0076] S2 Curing Agent Preparation: Mix the above curing agent components, add 8 kg of deionized water, and stir to form a uniform curing agent suspension;

[0077] S3 Curing treatment: Add 5 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0078] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0079] Comparative Example 4

[0080] This embodiment provides a solidification treatment agent for electrolytic cell overhaul residue, which includes 1 kg of calcium chloride, 5 kg of calcium hypochlorite, 2 kg of cement, and 1 kg of desulfurized gypsum.

[0081] A method for resource utilization of electrolytic cell overhaul residue includes the following steps:

[0082] S1 Raw material preparation: Take 10kg of electrolytic cell overhaul slag, crush it to make its particle size ≤10mm, then remove metal debris by magnetic separation, and then separate about 3.5kg of carbonaceous enrichment material and about 6.5kg of electrolyte-refractory material mixture by air separation.

[0083] S2 Curing Agent Preparation: Mix the above curing agent components, add 9 kg of deionized water, and stir to form a uniform curing agent suspension;

[0084] S3 Curing treatment: Add 3 kg of curing agent suspension to the electrolyte-refractory material mixture, stir thoroughly for 30 min, and let stand for 24 h to obtain the treated electrolytic cell overhaul slag solid.

[0085] S4 Carbon Material Processing: The carbon-enriched material is acid-washed with 3% dilute hydrochloric acid at room temperature for 40 minutes, filtered and washed until neutral, and then calcined at 850℃ for 2.5 hours under nitrogen protection to obtain modified carbon material.

[0086] The above-mentioned electrolytic cell overhaul slag originated from mixed waste slag generated during a major overhaul of an aluminum electrolytic cell. The components were analyzed as follows:

[0087] Fluorides (in F) - (Calculated as CN): 8200 mg / kg, cyanide (as CN) - (Total content): 65 mg / kg, carbon content: 38%, metal scrap: 2%, the remainder is refractory material and electrolyte.

[0088] The fluoride removal rate, cyanide removal rate, fluoride concentration in the leachate, cyanide concentration in the leachate, 7-day compressive strength, 28-day compressive strength, and permeability coefficient of the electrolytic cell overhaul residue after resource recovery treatment in the above embodiments and comparative examples were tested. The test methods are as follows:

[0089] Fluorides: GB / T 15555.11-1995 "Determination of Fluorides - Ion-Selective Electrode Method"

[0090] Cyanide: HJ 484-2009 "Determination of Cyanide in Water - Isonicotinic Acid-Barbituric Acid Spectrophotometric Method"

[0091] Leaching toxicity: HJ / T 299-2007 "Leaching Toxicity of Solid Waste - Leaching Methods - Sulfuric Acid and Nitric Acid Methods"

[0092] Compressive strength: GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete"

[0093] Permeability coefficient: GB / T 50123-2019 Standard for Geotechnical Testing Methods (Variable Head Method)

[0094] The results are shown in Table 1.

[0095] Table 1

[0096] Example 1 86.2 99.2 1.32 Not detected 0.55 2.32 <![CDATA[7.53×10 -8 ]]> Example 2 87.1 99.5 1.28 Not detected 0.58 2.48 <![CDATA[6.18×10 -8 ]]> Example 3 88.4 99.6 1.21 Not detected 0.60 2.61 <![CDATA[5.76×10 -8 ]]> Example 4 87.6 99.4 1.26 Not detected 0.57 2.42 <![CDATA[6.49×10 -8 ]]> Comparative Example 1 41.8 98.5 4.78 Not detected 0.45 2.31 <![CDATA[2.13×10 -7 ]]> Comparative Example 2 85.3 27.9 1.35 46.8 0.57 2.28 <![CDATA[1.82×10 -7 ]]> Comparative Example 3 83.5 99.0 1.34 Not detected 0.50 1.97 <![CDATA[1.51×10 -7 ]]> Comparative Example 4 71.6 94.3 2.34 11.2 0.35 1.58 <![CDATA[3.47×10 -7 ]]>

[0097] As can be seen from the comparison of the test results of Examples 1-3 and Comparative Examples 1-5 in Table 1, the fluoride leaching concentration and cyanide leaching concentration of the electrolytic cell overhaul residue solids treated in the embodiments of the present invention are significantly lower than the limits specified in the "Hazardous Waste Landfill Standard" (GB 18598-2019) (where fluoride ≤120 mg / L and cyanide ≤6 mg / L), and the fluoride removal rate is stably above 85%, and the cyanide removal rate is as high as above 99%, achieving efficient stabilization of fluoride and cyanide pollutants.

[0098] In this embodiment of the invention, after gypsum was used to replace part of the calcium chloride and cement, the mechanical properties and impermeability of the solidified body both met the standards for safe landfill entry, specifically, the 7-day compressive strength ≥ 0.5 MPa, the 28-day compressive strength ≥ 2.0 MPa, and the permeability coefficient ≤ 10. -7 The speed of cm / s ensures the structural stability of the solidified body during landfilling, preventing secondary leakage and pollution. Meanwhile, compared to traditional solidification processes, this invention reduces raw material costs by 40% and shortens the processing cycle to 3-5 days, significantly improving the economic efficiency and engineering applicability of the process.

[0099] The above comparison results fully demonstrate that the curing agent formulation and corresponding treatment method disclosed in this invention are significantly superior to the comparative proportions in terms of fluoride and cyanide removal efficiency, and the mechanical properties and anti-permeability properties of the cured body are also more advantageous. More importantly, the introduction of gypsum components not only reduces raw material costs, but also further improves the long-term stability and environmental safety of the cured body.

[0100] The test results of each comparative example show that the absence of any key component (such as gypsum) in the curing agent of the present invention, or the change of the ratio range of each component, will lead to a significant decrease in the pollutant removal rate, a decrease in the mechanical and anti-permeability properties of the cured body, or a significant increase in the treatment cost. This fully demonstrates that there is a synergistic effect among the components in the curing agent of the present invention, and that each component is indispensable. Together, they achieve multiple technical goals of simultaneous and efficient stabilization of fluorine and cyanide, compliance with the performance standards of the cured body, and cost optimization.

[0101] In summary, this invention, by rationally introducing gypsum components into the curing agent formulation and optimizing the distribution ratio of each component, not only effectively solves the technical defects existing in the traditional co-curing treatment of hazardous waste fluorocyanide, achieving efficient and stable curing of fluorocyanide pollutants, but also significantly reduces disposal costs and treatment cycles, taking into account harmless treatment, resource utilization and economic benefits, and possesses outstanding inventiveness and practicality.

[0102] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A solidifying agent for electrolytic cell overhaul residue, characterized in that, The curing agent components include calcium chloride, calcium hypochlorite, cement and gypsum, and the mass ratio of calcium chloride, calcium hypochlorite, cement and gypsum is (1~1.2):(5~6):(2~3):(1~2).

2. The electrolytic cell overhaul slag solidifying agent according to claim 1, characterized in that, The mass ratio of calcium chloride, calcium hypochlorite, cement, and gypsum is 1:5.5:2:1.

5.

3. The curing agent for electrolytic overhaul tanks according to claim 1 or 2, characterized in that, The cement is ordinary Portland cement with a grade of not less than 42.5; the gypsum is at least one of desulfurized gypsum, natural gypsum, or building gypsum.

4. The electrolytic cell overhaul residue solidifying agent according to claim 1, characterized in that, The mass ratio of the curing agent component to water is 1:(1~1.5), and the amount of the curing agent mixed suspension added accounts for 45~61% of the mass of the electrolytic cell overhaul residue.

5. A method for resource utilization of electrolytic cell overhaul residue, characterized in that, Includes the following steps: S1 grinds and classifies the slag from the electrolytic cell overhaul to obtain carbonaceous enriched material and electrolyte-refractory material mixture, respectively. S2 Preparation of curing agent: Add the curing agent according to any one of claims 1-4 to water and mix evenly to form a curing agent mixed suspension; S3. Add the curing agent mixed suspension to the electrolyte-refractory material mixture at 45-61% of the mass of the electrolytic cell overhaul residue, stir, react, and obtain the treated electrolytic cell overhaul residue.

6. The method for resource utilization of electrolytic cell overhaul residue according to claim 5, characterized in that, The particle size of the overhaul residue from the electrolytic cell after grinding is ≤10mm.

7. The method for resource utilization of electrolytic cell overhaul residue according to claim 5, characterized in that, The grading and sorting includes magnetic separation and air separation; the magnetic separation is to remove metal debris from the overhaul slag of the electrolytic cell by adsorption with a magnet; the air separation is to separate the carbonaceous enriched material from the electrolyte-refractory material by using different air forces.

8. The method for resource utilization of electrolytic cell overhaul residue according to claim 5, characterized in that, After acid washing, the carbonaceous enriched material is calcined to obtain the modified carbon material.

9. The method for resource utilization of electrolytic cell overhaul residue according to claim 5, characterized in that, The electrolytic cell overhaul residue processed in step S3 is used as refractory brick material.

10. The method for resource utilization of electrolytic cell overhaul residue according to claim 8, characterized in that, The pickling uses 3-5% dilute hydrochloric acid; the calcination is carried out under inert gas protection at a temperature of 800-900℃ for 2-3 hours.

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