Innocent treatment process of solid waste

Abstract

The invention discloses a harmless treatment process of solid waste, and relates to the technical field of solid waste treatment, the process comprises the following steps: crushing the solid waste into small blocks, drying to obtain dried solid waste, and crushing the dried solid waste to obtain pretreated solid waste; and then at room temperature, spraying the liquid A on the surface of the pretreated solid waste by using a nanoscale spray gun, stirring, spraying the liquid B, continuously stirring, finally adding a neutralizing solution, treating, and naturally ventilating to finish the harmless treatment of the solid waste. The pH value of the solid waste obtained through the harmless treatment process for the solid waste is remarkably reduced, the leaching concentration of heavy metal is far lower than the standard limit value, and the treatment process has the good cost advantage.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment technology, and more specifically to a harmless treatment process for solid waste. Background Technology

[0002] Strongly alkaline solid wastes generated during industrial production (such as aluminum red mud) are classified as highly alkaline hazardous wastes. They contain large amounts of soluble alkalis such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium aluminate, and sodium silicate. Once released into the environment, these substances pollute the soil, hinder vegetation growth, damage aquatic ecosystems, and corrode buildings, pipelines, and seepage prevention facilities. Under alkaline conditions, some heavy metals migrate in anionic form (such as arsenate and chromate), which are highly unstable and easily leach into aquatic environments with rainwater, posing a threat to human health through the food chain. Large-scale stockpiling of solid waste not only occupies land resources but also requires significant investment in the construction and maintenance of stockpiles, posing substantial environmental risks and resulting in challenging, time-consuming, and costly remediation processes.

[0003] Currently, the most common method for treating solid waste (such as highly alkaline solid waste) is acid-base neutralization. However, strong acids are costly, highly corrosive, and easily damage equipment. Furthermore, acid neutralization can lead to the re-dissolution of heavy metals, causing secondary pollution. Carbon dioxide neutralization is inefficient, slow, and difficult to deeply remove alkali; it can only adjust pH and cannot stabilize heavy metals. Resource utilization of solid waste, producing cement, bricks, and roadbed materials, and recovering iron, aluminum, rare earth elements, etc., shows promising research prospects.

[0004] However, highly alkaline solid wastes such as aluminum red mud affect the strength and durability of building materials. Heavy metals in solid waste pose a potential risk of excessive leaching, which limits their application scenarios. Moreover, current agents for reducing heavy metal leaching can usually only stabilize some heavy metals and are prone to failure in highly alkaline environments. In addition, the high cost of these agents also limits the engineering promotion and application of solid waste treatment processes.

[0005] Therefore, there is an urgent need for a harmless treatment process that is low-cost, effective, and free from secondary pollution, and can simultaneously reduce the pH of solid waste and the concentration of heavy metal leaching. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a process for the harmless treatment of solid waste.

[0007] The objective of this invention can be achieved through the following technical solutions: A process for the harmless treatment of solid waste includes the following steps: Step (1): Crush the solid waste into small pieces and dry them to obtain dried solid waste; then crush the dried solid waste to obtain pretreated solid waste. Step (2): At room temperature, use a nano-spray gun to spray liquid A onto the surface of the pretreated solid waste, stir, then spray liquid B, continue stirring, and finally add neutralizing liquid, stir evenly, and after natural ventilation, the harmless treatment of solid waste is completed.

[0008] Furthermore, the harmless treatment process for solid waste includes the following specific steps: Step (1): Crush the solid waste into small pieces and dry them at 105-110℃ for 4-6 hours to obtain dried solid waste; then crush the dried solid waste to obtain pretreated solid waste. Furthermore, the solid waste is selected from one of the following: aluminum red mud, fly ash, coal gangue, polluted river mud, polluted soil, and solid waste from rare earth production. Furthermore, the solid waste is selected from aluminum red mud or fly ash; Furthermore, the dimensions of the small pieces are: thickness ranging from 1-3 cm, side length ranging from 3-5 cm; the moisture content of the solid waste is 28-40%; the moisture content of the dried solid waste is less than 10%. Furthermore, the particle size of the pretreated solid waste is 95-105 mesh; Step (2): At room temperature, use a nano-level spray gun to spray liquid A onto the surface of the pretreated solid waste and stir for 30-40 minutes. Then spray liquid B and continue stirring for 30-40 minutes. Finally, add the neutralizing liquid and stir for 1-1.5 hours. After natural ventilation for 36-48 hours, the harmless treatment of the solid waste is completed. Furthermore, the ratio of the amount of pretreated solid waste, liquid A, liquid B, and neutralization solution is 100-105g: 10-12mL: 13-15mL: 15-20mL; Furthermore, the neutralization solution is obtained by mixing and stirring desulfurized gypsum, citric acid, and water in a ratio of 10-12g: 1-3g: 20-30mL.

[0009] Further, solution A comprises the following raw materials in parts by weight: 15-25 parts ferrous sulfate, 5-10 parts calcium chloride, 65-75 parts deionized water, 0.3-0.5 parts trisodium citrate, and 0.2-0.4 parts nonionic surfactant.

[0010] Furthermore, the preparation method of solution A is as follows: mix trisodium citrate and deionized water, add ferrous sulfate and stir, then add calcium chloride and stir, add nonionic surfactant, stir evenly, and let stand to obtain solution A.

[0011] Furthermore, the specific preparation method of solution A is as follows: mix trisodium citrate and deionized water and stir for 5-7 minutes, then add ferrous sulfate and stir for 3-5 minutes, add calcium chloride and stir for 8-10 minutes, add nonionic surfactant and stir for 10-12 minutes, and let stand for 5-7 minutes to obtain solution A.

[0012] Furthermore, solution B comprises the following raw materials in parts by weight: 10-15 parts diammonium hydrogen phosphate, 5-7 parts additives, 80-90 parts deionized water, and 0.2-0.4 parts nonionic surfactant.

[0013] Furthermore, the preparation method of solution B is as follows: diammonium hydrogen phosphate and deionized water are mixed and stirred, additives are added and stirred, then nonionic surfactants are added, stirred evenly, and allowed to stand to obtain solution B.

[0014] Furthermore, the specific preparation method of solution B is as follows: mix diammonium hydrogen phosphate and deionized water and stir for 3-5 minutes, add additives and stir for 15-20 minutes, then add nonionic surfactants and stir for 15-17 minutes, let stand for 8-10 minutes to obtain solution B.

[0015] Furthermore, the nonionic surfactant is Tween 80 or PEG-400.

[0016] Furthermore, the preparation method of the additive includes the following steps: Step A1: In a protective gas atmosphere, sodium hydroxide and anhydrous ethanol are mixed and stirred, and allyl mercaptan is added dropwise while controlling the temperature during the addition. After the addition is complete, the mixture is stirred, rotary evaporated, and dried with anhydrous sodium sulfate to obtain product a. Step A2: Mix benzotriazole and anhydrous ethanol, add potassium carbonate and stir, add allyl bromide, maintain temperature, stir at room temperature after addition, filter, rotary evaporate the filtrate, and dry with anhydrous sodium sulfate to obtain product b; Step A3: Add sodium acrylate, product a, and product b to deionized water, stir under a protective gas atmosphere, heat in a water bath, add initiator, stir at a constant temperature, cool, add anhydrous ethanol and stir, let stand, filter, wash with anhydrous ethanol, and vacuum dry to obtain the additive.

[0017] Furthermore, the preparation method of the additive includes the following specific steps: Step A1: In a protective gas atmosphere, sodium hydroxide and anhydrous ethanol are mixed and stirred for 40-45 min. Allyl mercaptan is added dropwise, with the temperature controlled at ≤30℃ during the addition. After the addition is complete, the mixture is stirred for 0.5-1 h, rotary evaporated, and dried with anhydrous sodium sulfate to obtain product a. Furthermore, the ratio of sodium hydroxide, anhydrous ethanol, and allyl mercaptan is 4.5-5g: 45-50mL: 7.5-8g; In step A1, the thiols of allyl mercaptan are converted into sodium thiolate to obtain product a; Step A2: Mix benzotriazole and anhydrous ethanol and stir for 5-7 min. Add potassium carbonate and stir for 20-25 min. Add allyl bromide and keep the temperature ≤35℃. Add the bromide over 15-20 min. Stir at room temperature for 4-5 h. Filter the mixture. Rotary evaporate the filtrate and dry it with anhydrous sodium sulfate to obtain product b. Furthermore, the ratio of benzotriazole, anhydrous ethanol, potassium carbonate, and allyl bromide used is 12-12.5g: 50-60mL: 17-17.5g: 13.5-14g; In step A2, benzotriazole reacts with allyl bromide to give benzotriazole containing a terminal double bond, i.e., product b; Step A3: Add sodium acrylate, product a, and product b to deionized water, stir for 15-20 min in a protective gas atmosphere, heat to 50-60℃ in a water bath, add initiator, stir at constant temperature for 4-5 h, cool to room temperature, add anhydrous ethanol and stir for 10-12 min, let stand for 5-7 min, filter, wash with anhydrous ethanol, and vacuum dry for 6-8 h to obtain the additive; Furthermore, the ratio of sodium acrylate, product a, product b, deionized water, and initiator is 7.5-8g: 1-1.5g: 1.8-2.3g: 40-50mL: 0.35-0.4g; the initiator is ammonium persulfate. In step A3, sodium acrylate, product a, and product b are polymerized by an initiator to obtain an additive.

[0018] This invention discloses a harmless treatment process for solid waste. The process involves crushing the solid waste into small pieces and drying it to obtain dried solid waste. The dried solid waste is then pulverized to obtain pretreated solid waste. At room temperature, liquid A is first sprayed onto the surface of the pretreated solid waste using a nano-scale spray gun and stirred. Then, liquid B is sprayed and stirred again. Finally, a neutralizing liquid is added for further treatment. After natural ventilation, the harmless treatment of the solid waste is completed.

[0019] The beneficial effects of this invention are: 1. The A solution used in this invention is prepared from ferrous sulfate, calcium chloride, deionized water, trisodium citrate, and nonionic surfactants; the B solution is prepared from diammonium hydrogen phosphate, additives, deionized water, and nonionic surfactants; and the neutralization solution is obtained by mixing desulfurized gypsum, citric acid, and water. This invention involves spraying the pretreated solid waste with the A solution first, followed by the B solution, and then adding the neutralization solution at room temperature. This operation not only avoids the direct mixing of ions in the A and B solutions, preventing precipitation and ineffectiveness, but also reduces the treatment cost of solid waste, significantly reduces the leaching concentration of heavy metals and alkalinity in the solid waste, and has good harmless and environmentally friendly properties.

[0020] 2. In this invention, solution A is first sprayed onto the surface of the pretreated solid waste. Ferrous ions provided by ferrous sulfate in solution A reduce hexavalent chromium ions in the pretreated solid waste to trivalent chromium ions, while the ferrous ions are oxidized to ferric ions. Calcium ions in solution A react with arsenate ions in the pretreated solid waste to form an insoluble calcium arsenate precipitate. Under the alkaline conditions of the pretreated solid waste, ferric ions form ferric hydroxide gel, further leading to an iron-arsenic coprecipitate. Then, solution B is sprayed. Diammonium hydrogen phosphate in solution B provides phosphate ions, which can react with trivalent chromium ions to form chromium phosphate. The sparingly soluble precipitate can also form mercuric phosphate precipitate with mercury ions in the pretreated solid waste, reducing the leaching concentration of heavy metal ions in the pretreated solid waste. Finally, a neutralizing solution is added, in which the addition of citric acid helps to form a uniform slurry with desulfurized gypsum and water, and can also gently reduce the concentration of hydroxide and carbonate ions, avoiding a sudden drop in pH that could lead to the re-dissolution of heavy metals. Desulfurized gypsum can replenish calcium ions, further precipitating residual arsenate ions, and at the same time reacting with residual carbonate and hydroxide ions to form precipitates, thereby effectively reducing the pH of the pretreated solid waste.

[0021] 3. The additive used in solution B of this invention is obtained by polymerizing sodium acrylate, product a, and product b under the action of an initiator. Sodium thiolate in product a is oxidized to disulfide bonds. The additive not only enhances dispersion, making the prepared solution B more uniform and stable, eliminating the need for additional dispersants, but also chelates mercury ions through disulfide bonds, converting them into stable, insoluble chelates. Benzotriazole not only synergistically chelates mercury ions but also forms stable complexes with trivalent chromium ions through the nitrogen atom on the triazole ring, significantly reducing the leaching concentrations of mercury and chromium ions and achieving simultaneous stabilization of mercury and chromium. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all 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 scope of protection of the present invention.

[0023] Example 1 The preparation method of the additive includes the following steps: Step A1: In nitrogen atmosphere, sodium hydroxide and anhydrous ethanol were mixed and stirred for 40 min. Allyl mercaptan was added dropwise, with the temperature controlled at 25℃ during the addition. After the addition was complete, the mixture was stirred for 0.5 h, rotary evaporated at 30℃, and dried with anhydrous sodium sulfate to obtain product a. The ratio of sodium hydroxide, anhydrous ethanol, and allyl mercaptan was 4.5 g: 45 mL: 7.5 g. Step A2: Mix benzotriazole and anhydrous ethanol and stir for 5 min. Add potassium carbonate and stir for 20 min. Add allyl bromide and maintain the temperature at 30℃. Add the mixture over 15 min. Stir at room temperature for 4 h. Filter the mixture. Rotate the filtrate at 35℃ and dry it with anhydrous sodium sulfate to obtain product b. The ratio of benzotriazole, anhydrous ethanol, potassium carbonate, and allyl bromide is 12 g: 50 mL: 17 g: 13.5 g. Step A3: Add sodium acrylate, product a, and product b to deionized water, stir for 15 min in a nitrogen atmosphere, heat to 50°C in a water bath, add ammonium persulfate, stir at a constant temperature for 4 h, cool to room temperature, add anhydrous ethanol and stir for 10 min, let stand for 5 min, filter, wash three times with anhydrous ethanol, and vacuum dry at 40°C for 6 h to obtain the additive; the ratio of sodium acrylate, product a, product b, deionized water, and ammonium persulfate is 7.5 g: 1 g: 1.8 g: 40 mL: 0.35 g.

[0024] Example 2 The preparation method of the additive includes the following steps: Step A1: In nitrogen atmosphere, sodium hydroxide and anhydrous ethanol were mixed and stirred for 43 min. Allyl mercaptan was added dropwise, with the temperature controlled at 25℃ during the addition. After the addition was complete, the mixture was stirred for 0.7 h, rotary evaporated at 30℃, and dried with anhydrous sodium sulfate to obtain product a. The ratio of sodium hydroxide, anhydrous ethanol, and allyl mercaptan was 4.8 g: 47 mL: 7.8 g. Step A2: Mix benzotriazole and anhydrous ethanol and stir for 6 min. Add potassium carbonate and stir for 23 min. Add allyl bromide and maintain the temperature at 30℃. Add the mixture over 17 min. Stir at room temperature for 4.5 h. Filter the mixture. Rotate the filtrate at 35℃ and dry it with anhydrous sodium sulfate to obtain product b. The ratio of benzotriazole, anhydrous ethanol, potassium carbonate, and allyl bromide is 12.3 g: 55 mL: 17.3 g: 13.7 g. Step A3: Add sodium acrylate, product a, and product b to deionized water, stir for 17 min under a nitrogen atmosphere, heat to 55°C in a water bath, add ammonium persulfate, stir at a constant temperature for 4.5 h, cool to room temperature, add anhydrous ethanol and stir for 11 min, let stand for 6 min, filter, wash three times with anhydrous ethanol, and vacuum dry at 40°C for 7 h to obtain the additive; the ratio of sodium acrylate, product a, product b, deionized water, and ammonium persulfate is 7.8 g: 1.2 g: 2.0 g: 45 mL: 0.37 g.

[0025] Example 3 The preparation method of the additive includes the following steps: Step A1: In nitrogen atmosphere, sodium hydroxide and anhydrous ethanol are mixed and stirred for 45 min. Allyl mercaptan is added dropwise, and the temperature is controlled at 25℃ during the dropwise addition. After the addition is complete, the mixture is stirred for 1 h, rotary evaporated at 30℃, and dried with anhydrous sodium sulfate to obtain product a. The ratio of sodium hydroxide, anhydrous ethanol, and allyl mercaptan is 5 g: 50 mL: 8 g. Step A2: Mix benzotriazole and anhydrous ethanol and stir for 7 min. Add potassium carbonate and stir for 25 min. Add allyl bromide and maintain the temperature at 30℃. Add the mixture over 20 min. Stir at room temperature for 5 h. Filter the mixture. Rotate the filtrate at 35℃ and dry it with anhydrous sodium sulfate to obtain product b. The ratio of benzotriazole, anhydrous ethanol, potassium carbonate, and allyl bromide is 12.5 g: 60 mL: 17.5 g: 14 g. Step A3: Add sodium acrylate, product a, and product b to deionized water, stir for 20 min in a nitrogen atmosphere, heat to 60°C in a water bath, add ammonium persulfate, stir at a constant temperature for 5 h, cool to room temperature, add anhydrous ethanol and stir for 12 min, let stand for 7 min, filter, wash three times with anhydrous ethanol, and vacuum dry at 40°C for 8 h to obtain the additive; the ratio of sodium acrylate, product a, product b, deionized water, and ammonium persulfate is 8 g: 1.5 g: 2.3 g: 50 mL: 0.4 g.

[0026] Example 4 A process for the harmless treatment of solid waste includes the following steps: Step (1): Mechanically crush the aluminum red mud into small pieces and dry them at 105℃ for 4 hours to obtain dried aluminum red mud; pulverize the dried aluminum red mud to obtain pretreated aluminum red mud; the size of the small pieces is: thickness range of 1-3cm, side length range of 3-5cm; the moisture content of the aluminum red mud is 28%; the moisture content of the dried aluminum red mud is 4%; the particle size of the pretreated aluminum red mud is 95 mesh; Step (II): At room temperature, using a nano-level spray gun (supplier: Henan Riyi Hardware Tools Co., Ltd., model: T-AGPZ spray gun), first spray liquid A onto the surface of the pretreated aluminum red mud at a spray rate of 4 mL / min, stir for 30 min, then spray liquid B at a spray rate of 2 mL / min, continue stirring for 30 min, finally add neutralizing liquid, stir for 1 h, and after natural ventilation for 36 h, the harmless treatment of solid waste is completed; the ratio of pretreated aluminum red mud, liquid A, liquid B, and neutralizing liquid is 100 g: 10 mL: 13 mL: 15 mL; the neutralizing liquid is obtained by mixing desulfurized gypsum, citric acid, and water in a ratio of 10 g: 1 g: 20 mL and stirring for 20 min.

[0027] Solution A comprises the following raw materials in parts by weight: 15 parts ferrous sulfate, 5 parts calcium chloride, 65 parts deionized water, 0.3 parts trisodium citrate, and 0.2 parts Tween 80. The preparation method for Solution A is as follows: Mix trisodium citrate and deionized water and stir for 5 minutes; then add ferrous sulfate and stir for 3 minutes; add calcium chloride and stir for 8 minutes; add Tween 80 and stir for 10 minutes; let stand for 5 minutes to obtain Solution A.

[0028] Solution B comprises the following raw materials in parts by weight: 10 parts diammonium hydrogen phosphate, 5 parts additive obtained in Example 1, 80 parts deionized water, and 0.2 parts Tween 80. Solution B is prepared by mixing and stirring diammonium hydrogen phosphate and deionized water for 3 minutes, adding the additive obtained in Example 1, stirring for 15 minutes, then adding Tween 80, stirring for 15 minutes, and letting stand for 8 minutes to obtain solution B.

[0029] Example 5 A process for the harmless treatment of solid waste includes the following steps: Step (1): Mechanically crush the aluminum red mud into small pieces and dry them at 107℃ for 5 hours to obtain dried aluminum red mud; pulverize the dried aluminum red mud to obtain pretreated aluminum red mud; the size of the small pieces: thickness range 1-3cm, side length range 3-5cm; the moisture content of the aluminum red mud is 33%; the moisture content of the dried aluminum red mud is 5.2%; the particle size of the pretreated aluminum red mud is 100 mesh; Step (II): At room temperature, using a nano-level spray gun (supplier: Henan Riyi Hardware Tools Co., Ltd., model: T-AGPZ spray gun), first spray liquid A onto the surface of the pretreated aluminum red mud at a spray rate of 4 mL / min, stir for 35 min, then spray liquid B at a spray rate of 2 mL / min, continue stirring for 35 min, finally add neutralizing liquid, stir for 1.3 h, and after natural ventilation for 42 h, the harmless treatment of solid waste is completed; the ratio of pretreated aluminum red mud, liquid A, liquid B, and neutralizing liquid is 103 g: 11 mL: 14 mL: 17 mL; the neutralizing liquid is obtained by mixing desulfurized gypsum, citric acid, and water in a ratio of 11 g: 2 g: 25 mL and stirring for 20 min.

[0030] Solution A comprises the following raw materials in parts by weight: 20 parts ferrous sulfate, 8 parts calcium chloride, 70 parts deionized water, 0.4 parts trisodium citrate, and 0.3 parts PEG-400. The preparation method for Solution A is as follows: Mix trisodium citrate and deionized water and stir for 6 minutes; then add ferrous sulfate and stir for 4 minutes; add calcium chloride and stir for 9 minutes; add PEG-400 and stir for 11 minutes; let stand for 6 minutes to obtain Solution A.

[0031] Solution B comprises the following raw materials in parts by weight: 13 parts diammonium hydrogen phosphate, 6 parts additive obtained in Example 2, 85 parts deionized water, and 0.3 parts PEG-400. Solution B is prepared as follows: diammonium hydrogen phosphate and deionized water are mixed and stirred for 4 minutes, the additive obtained in Example 2 is added, and the mixture is stirred for 17 minutes. Then PEG-400 is added, and the mixture is stirred for 16 minutes. After standing for 9 minutes, solution B is obtained.

[0032] Example 6 A process for the harmless treatment of solid waste includes the following steps: Step (1): Mechanically crush the aluminum red mud into small pieces and dry them at 110℃ for 6 hours to obtain dried aluminum red mud; pulverize the dried aluminum red mud to obtain pretreated aluminum red mud; the size of the small pieces: thickness range 1-3cm, side length range 3-5cm; the moisture content of the aluminum red mud is 40%; the moisture content of the dried aluminum red mud is 3.6%; the particle size of the pretreated aluminum red mud is 105 mesh; Step (II): At room temperature, using a nano-level spray gun (supplier: Henan Riyi Hardware Tools Co., Ltd., model: T-AGPZ spray gun), first spray liquid A onto the surface of the pretreated aluminum red mud at a spray rate of 4 mL / min, stir for 40 min, then spray liquid B at a spray rate of 2 mL / min, continue stirring for 40 min, finally add neutralizing liquid, stir for 1.5 h, and after natural ventilation for 48 h, the harmless treatment of solid waste is completed; the ratio of pretreated aluminum red mud, liquid A, liquid B, and neutralizing liquid is 105 g: 12 mL: 15 mL: 20 mL; the neutralizing liquid is obtained by mixing desulfurized gypsum, citric acid, and water in a ratio of 12 g: 3 g: 30 mL and stirring for 20 min.

[0033] Solution A comprises the following raw materials in parts by weight: 25 parts ferrous sulfate, 10 parts calcium chloride, 75 parts deionized water, 0.5 parts trisodium citrate, and 0.4 parts PEG-400. The preparation method for Solution A is as follows: Mix trisodium citrate and deionized water and stir for 7 minutes; then add ferrous sulfate and stir for 5 minutes; add calcium chloride and stir for 10 minutes; add PEG-400 and stir for 12 minutes; let stand for 7 minutes to obtain Solution A.

[0034] Solution B comprises the following raw materials in parts by weight: 15 parts diammonium hydrogen phosphate, 7 parts additive obtained in Example 3, 90 parts deionized water, and 0.4 parts PEG-400. Solution B is prepared as follows: diammonium hydrogen phosphate and deionized water are mixed and stirred for 5 minutes, the additive obtained in Example 3 is added, and the mixture is stirred for 20 minutes. Then PEG-400 is added, and the mixture is stirred for 17 minutes. The mixture is then allowed to stand for 10 minutes to obtain solution B.

[0035] Comparative Example 1 Compared with Example 6, in step (ii), liquid B is sprayed first, followed by liquid A, and the rest is exactly the same as in Example 6, thus completing the harmless treatment of solid waste; Specifically, at room temperature, using a nano-level spray gun (supplier: Henan Riyi Hardware Tools Co., Ltd., model: T-AGPZ spray gun), liquid B was first sprayed onto the surface of the pretreated solid waste at a spraying rate of 2 mL / min, and stirred for 40 min. Then, liquid A was sprayed at a spraying rate of 4 mL / min, and stirring was continued for 40 min. Finally, neutralizing liquid was added, and stirring was carried out for 1.5 h. After natural ventilation for 48 h, the harmless treatment of solid waste was completed. The ratio of pretreated aluminum red mud, liquid A, liquid B, and neutralizing liquid was 105 g: 12 mL: 15 mL: 20 mL. The neutralizing liquid was obtained by mixing desulfurized gypsum, citric acid, and water in a ratio of 12 g: 3 g: 30 mL and stirring for 20 min.

[0036] Comparative Example 2 Compared with Example 6, in step (ii), the neutralizing liquid is added first, then liquid A is sprayed, and then liquid B is sprayed. The rest is exactly the same as in Example 6, thus completing the harmless treatment of solid waste. Specifically, at room temperature, the pretreated solid waste and neutralization solution were mixed and stirred for 1.5 hours. Then, using a nano-level spray gun (supplier: Henan Riyi Hardware Tools Co., Ltd., model: T-AGPZ spray gun), solution A was sprayed at a spray rate of 4 mL / min, and stirring was continued for 40 minutes. Then, solution B was sprayed at a spray rate of 2 mL / min, and stirring was continued for 40 minutes. After natural ventilation for 48 hours, the harmless treatment of the solid waste was completed. The ratio of pretreated aluminum red mud, solution A, solution B, and neutralization solution was 105 g: 12 mL: 15 mL: 20 mL. The neutralization solution was obtained by mixing desulfurized gypsum, citric acid, and water in a ratio of 12 g: 3 g: 30 mL and stirring for 20 minutes.

[0037] Comparative Example 3 Compared with Example 6, the benzotriazole used in the preparation process of the additive was replaced with 2-amino-4,6-methoxy-1,3,5-triazine, and the rest was completely the same as in Example 6, thus completing the harmless treatment of solid waste.

[0038] Comparative Example 4 Compared with Example 6, product a in the preparation process of the additive used was replaced with allyl methyl sulfide, and the rest was completely the same as in Example 6, thus completing the harmless treatment of solid waste.

[0039] Comparative Example 5 Compared with Example 6, the A liquid used was replaced with A liquid-1, and everything else was exactly the same as in Example 6, thus completing the harmless treatment of solid waste; The preparation method of solution A-1 is as follows: ferrous sulfate and deionized water are mixed and stirred for 7 min, calcium chloride is added and stirred for 10 min, trisodium citrate is added and stirred for 5 min, PEG-400 is added and stirred for 12 min, and then allowed to stand for 7 min to obtain solution A-1; solution A-1 includes the following raw materials in parts by weight: 25 parts ferrous sulfate, 10 parts calcium chloride, 75 parts deionized water, 0.5 parts trisodium citrate, and 0.4 parts PEG-400.

[0040] The following is a further effect test on the solid waste obtained by the harmless treatment process of solid waste in Examples 4-6 and Comparative Examples 1-5 of the present invention. The test results are shown below.

[0041] The pH value of the solid waste obtained after treatment was tested in accordance with GB 5085.1-2007 "Identification Standard for Hazardous Waste - Corrosivity Identification".

[0042] The leaching concentration of heavy metals in the treated solid waste was tested in accordance with GB 5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification".

[0043] The results are recorded in Table 1; Table 1: Performance Test Results

[0044] Note: ND indicates not detected.

[0045] According to the data in Table 1, the solid waste treated by the harmless treatment process of the present invention has a significantly reduced pH value and the heavy metal leaching concentration is far below the standard limit.

[0046] Comparing Example 6 with Comparative Example 1, it can be seen that in step (ii), liquid B is sprayed first and then liquid A is sprayed. This shows that the method of spraying liquid A first and then liquid B in this invention is more conducive to reducing the leaching concentration of heavy metals in solid waste.

[0047] Comparing Example 6 with Comparative Example 2, it can be seen that in step (ii), the neutralizing liquid is added first, then liquid A is sprayed, and then liquid B is sprayed. This shows that the method of spraying liquid A first, then liquid B, and then adding the neutralizing liquid in this invention is more conducive to reducing the pH value of solid waste and the leaching concentration of heavy metals.

[0048] A comparison of Example 6 and Comparative Example 3 shows that replacing benzotriazole in the additive preparation process with 2-amino-4,6-methoxy-1,3,5-triazine demonstrates that the use of benzotriazole in this invention is more beneficial in reducing the leaching concentration of mercury and chromium ions in solid waste.

[0049] A comparison of Example 6 and Comparative Example 4 shows that replacing product a in the preparation process of the additive with allyl methyl sulfide demonstrates that using product a in this invention is more beneficial for reducing the leaching concentration of mercury ions in solid waste.

[0050] A comparison of Example 6 and Comparative Example 5 shows that replacing the A solution used with A solution-1 indicates that the A solution used in this invention is more effective in reducing the leaching concentration of chromium ions in solid waste.

[0051] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A harmless treatment process for solid waste, characterized in that: Includes the following steps: Step (1): Crush the solid waste into small pieces and dry them to obtain dried solid waste; then crush the dried solid waste to obtain pretreated solid waste. Step (2): At room temperature, use a nano-spray gun to spray liquid A onto the surface of the pretreated solid waste, stir, then spray liquid B, continue stirring, and finally add neutralizing liquid, stir evenly, and after natural ventilation, the harmless treatment of solid waste is completed.

2. The solid waste harmless treatment process according to claim 1, characterized in that: The neutralizing solution is prepared by mixing desulfurized gypsum, citric acid, and water in a ratio of 10-12g: 1-3g: 20-30mL.

3. The solid waste harmless treatment process according to claim 1, characterized in that: Solution A comprises the following raw materials in parts by weight: 15-25 parts ferrous sulfate, 5-10 parts calcium chloride, 65-75 parts deionized water, 0.3-0.5 parts trisodium citrate, and 0.2-0.4 parts nonionic surfactant.

4. The solid waste harmless treatment process according to claim 1, characterized in that: The B solution comprises the following raw materials in parts by weight: 10-15 parts diammonium hydrogen phosphate, 5-7 parts additives, 80-90 parts deionized water, and 0.2-0.4 parts nonionic surfactant.

5. The solid waste harmless treatment process according to claim 1, characterized in that: The preparation method of solution A is as follows: mix trisodium citrate and deionized water, add ferrous sulfate and stir, then add calcium chloride and stir, add nonionic surfactant, stir evenly, and let stand to obtain solution A.

6. The solid waste harmless treatment process according to claim 1, characterized in that: The preparation method of solution B is as follows: diammonium hydrogen phosphate and deionized water are mixed and stirred, additives are added and stirred, then nonionic surfactants are added, stirred evenly, and allowed to stand to obtain solution B.

7. The solid waste harmless treatment process according to claim 4, characterized in that: The preparation method of the additive includes the following steps: Step A1: In a protective gas atmosphere, sodium hydroxide and anhydrous ethanol are mixed and stirred, and allyl mercaptan is added dropwise while controlling the temperature during the addition. After the addition is complete, the mixture is stirred, rotary evaporated, and dried with anhydrous sodium sulfate to obtain product a. Step A2: Mix benzotriazole and anhydrous ethanol, add potassium carbonate and stir, add allyl bromide, maintain temperature, stir at room temperature after addition, filter, rotary evaporate the filtrate, and dry with anhydrous sodium sulfate to obtain product b; Step A3: Add sodium acrylate, product a, and product b to deionized water, stir under a protective gas atmosphere, heat in a water bath, add initiator, stir at a constant temperature, cool, add anhydrous ethanol and stir, let stand, filter, wash with anhydrous ethanol, and vacuum dry to obtain the additive.

8. The solid waste harmless treatment process according to claim 7, characterized in that: In step A1, the ratio of sodium hydroxide, anhydrous ethanol, and allyl mercaptan is 4.5-5g: 45-50mL: 7.5-8g.

9. The solid waste harmless treatment process according to claim 7, characterized in that: In step A2, the ratio of the amount of benzotriazole, anhydrous ethanol, potassium carbonate, and allyl bromide is 12-12.5g: 50-60mL: 17-17.5g: 13.5-14g.

10. The solid waste harmless treatment process according to claim 7, characterized in that: In step A3, the ratio of sodium acrylate, product a, product b, deionized water, and initiator is 7.5-8g: 1-1.5g: 1.8-2.3g: 40-50mL: 0.35-0.4g.

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