A recycling method and system for fireworks and firecracker hazardous waste

Abstract

The application discloses a kind of fireworks and firecrackers hazardous waste recycling processing method and recycling processing system, comprising: waste water treatment step: waste water treatment step includes chemical precipitation step, A2O biochemical treatment step, Fenton oxidation step and BAF biological filter step, remove perchlorate, COD and heavy metal;Waste residue treatment step: waste residue treatment step includes wet grinding step, high temperature digestion step, flotation step, hydrocyclone separation step, wet leaching and step-by-step precipitation step, recover carbon powder, titanium, barium, aluminum, magnesium resources;Synergistic coupling mechanism: the bottom slag generated in waste water treatment step is transported to waste residue treatment step for processing, and the filtrate generated in waste residue treatment step is transported to waste water treatment step for processing.The application is to harmless treatment and resource recovery of fireworks and firecrackers hazardous waste.

Description

Technical Field

[0001] This invention pertains to the field of hazardous waste treatment from fireworks and firecrackers, and more specifically, relates to a method and system for recycling and treating hazardous waste from fireworks and firecrackers. Background Technology

[0002] Hazardous waste from fireworks and firecrackers encompasses various types. Waste generated during the production process includes waste gunpowder, waste black powder, waste fuses, waste display shells, waste rocket products, other waste fireworks and firecracker products, and waste semi-finished products containing explosives. Hazardous liquid waste is also present in areas such as sedimentation tanks, soaking tanks, and wastewater ditches. Waste raw materials discarded by enterprises are divided into waste reducing agents (such as aluminum powder, aluminum-magnesium alloy powder, metallic titanium powder, sulfur, etc.) and waste oxidizing agents (such as potassium nitrate, barium nitrate, potassium chlorate, etc.). In addition, wastewater generated from sedimentation, soaking, and filtration, as well as daily floor cleaning wastewater, also fall under the category of hazardous waste.

[0003] Currently, most fireworks and firecracker manufacturers use a three-stage sedimentation tank soaking method to treat waste. This method involves flushing the dry waste with water to remove its flammability and explosiveness, then introducing the supernatant from the sedimentation tank into an artificial wetland for biochemical treatment using aquatic plants such as Myriophyllum spicatum. While this method can meet local emission standards for characteristic pollutants, artificial wetlands have drawbacks such as requiring large areas, being affected by climate conditions, and having a treatment capacity that is mismatched with the amount of wastewater discharged by the manufacturers. Furthermore, the large amount of insoluble sludge generated by the three-stage sedimentation tank (mainly composed of sulfur, metal powder, and insoluble salts) still lacks effective treatment methods.

[0004] Existing related patent technologies also have limitations. Chinese patent CN110966902A discloses a safe treatment method for hazardous solid waste from fireworks and firecrackers, which involves dissolving the hazardous solid waste in water, mixing it with yellow mud to form a slurry, filtering it, drying it, and then crushing and sieving it. This method addresses the flammability and explosiveness of the hazardous waste, but it only addresses the flammability and explosiveness and does not recover any useful substances. Chinese patent CN115254916A discloses a treatment method for hazardous waste from fireworks and firecrackers, using flotation pretreatment to separate sulfur powder, charcoal powder, and metal powder. The bottom slag is reacted in a reactor before resource recovery. However, this method only recovers a portion of the usable resources using physical methods and does not effectively separate soluble salts and other components. Chinese patent CN119259662A discloses a harmless treatment method for hazardous solid waste from fireworks and firecracker production, using acid dissolution, alkali dissolution, and oxidation filtration to render the hazardous solid waste harmless, but it does not involve resource recovery.

[0005] Because current technologies have failed to simultaneously overcome the challenges of safe disposal and resource recycling of waste from the fireworks and firecrackers industry, and because there is a lack of mature industrialized treatment solutions in China, many fireworks companies have accumulated large amounts of waste awaiting disposal. This not only puts enormous pressure on production and operations but also poses serious safety hazards and environmental risks. Therefore, conducting research on the harmless and resource-based treatment of hazardous waste from fireworks and firecrackers can not only create considerable economic benefits but also has profound significance for ecological and environmental protection. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] Based on this, the present invention provides a method and system for recycling and processing hazardous waste from fireworks and firecrackers. The purpose of this invention is to harmlessly treat and recycle hazardous waste from fireworks and firecrackers.

[0008] (II) Technical Solution

[0009] To address the aforementioned technical problems, this invention proposes a method for recycling and treating hazardous waste from fireworks and firecrackers, comprising: a wastewater treatment step, including chemical precipitation, A2O biochemical treatment, Fenton oxidation, and BAF biological filter steps to remove perchlorate, COD, and heavy metals; a waste residue treatment step, including wet grinding, high-temperature digestion, flotation, hydrocyclone separation, wet leaching, and stepwise sedimentation steps to recover carbon powder, titanium, barium, aluminum, and magnesium resources; and a synergistic coupling mechanism, wherein the bottom slag generated in the wastewater treatment step is transported to the waste residue treatment step for processing, and the filtrate generated in the waste residue treatment step is transported to the wastewater treatment step for processing.

[0010] Furthermore, in the chemical precipitation step, sulfate and oxidant are added to the wastewater to form sulfate precipitate, and then the precipitate is separated from the liquid phase to obtain the first filtrate and the first bottom residue; the first filtrate is discharged after being treated in sequence through the A2O biochemical treatment step, the Fenton oxidation step, and the BAF biological filter step; the first bottom residue is transported to the flotation step for treatment.

[0011] Furthermore, the wet grinding step involves mixing waste residue and grinding aids to produce slurry through wet grinding; the high-temperature digestion step involves mixing the slurry and oxidant for a high-temperature digestion reaction, and the product after reaction undergoes solid-liquid separation to obtain a second filtrate and a second bottom slag, with the second filtrate being sent to the chemical precipitation step for treatment; the flotation step includes separating and recovering carbon powder from the slurry containing the second bottom slag using an airlift microbubble aeration method; the hydrocyclone separation step involves using hydrocyclone to perform solid-liquid separation on the bottom sludge from which carbon powder has been separated, obtaining an underflow portion and an overflow portion; the flotation step also includes separating and recovering barium sulfate and titanium dioxide from the underflow portion using a combination of airlift microbubbles and flotation reagents; the wet leaching step and the stepwise precipitation step involve reacting the overflow portion with the leachate, adding dilute acid after the reaction to precipitate aluminum salts first, adding dilute alkali after separating the aluminum salt precipitate to precipitate magnesium salts, and sending the third filtrate after magnesium salt precipitation and separation to the chemical precipitation step for treatment.

[0012] Furthermore, it also includes an exhaust gas treatment step, which involves absorbing the waste gas generated by the wet grinding step and the high-temperature digestion step, and spraying the waste gas with an alkaline absorption liquid to absorb and recover sulfur from the waste gas.

[0013] A recycling system for hazardous waste from fireworks and firecrackers, employing the aforementioned recycling and treatment method, comprises: a wastewater treatment subsystem, including chemical precipitation, A2O biochemical treatment, Fenton oxidation, and BAF biological filter; and a waste residue treatment subsystem, including wet grinding, high-temperature digestion, flotation, hydrocyclone separation, wet leaching, and stepwise sedimentation.

[0014] Furthermore, the chemical precipitation involves treating wastewater in a stirred reaction tank by adding sulfate and oxidant to the wastewater; controlling the reaction pH to 8.5~11.0 to precipitate barium salt-containing waste residue; separating the precipitate from the liquid phase using a solid-liquid separation device to obtain a first filtrate and a first bottom residue; the first bottom residue is then transported to flotation for treatment; the first filtrate is then discharged after sequentially undergoing A2O biochemical treatment, Fenton oxidation, and BAF biological filter treatment.

[0015] Furthermore, the wet grinding includes: grinding the waste residue using a wet grinding mill, adding grinding aids to the wet grinding mill; controlling the pH of the slurry formed by grinding to be 10.0~12.0; the high-temperature digestion includes: putting the slurry generated by wet grinding into a high-temperature digestion kettle; adding an oxidant to the high-temperature digestion kettle, and heating the high-temperature digestion kettle to 80~150℃; the heating is carried out in a stepwise manner: pre-oxidizing at 60~100℃ for 10~20 minutes, then heating to the target temperature at 3~5℃ / min, and after the reaction is completed, the cooling rate is controlled by a stepwise cooling method, first cooling to 100℃ at 2~3℃ / min, then naturally cooling to below 80℃ and then discharging to a filter press, and performing solid-liquid separation through the filter press to obtain a second filtrate and a second bottom residue, and the second filtrate is sent to a chemical precipitation treatment.

[0016] Furthermore, it also includes exhaust gas treatment, wherein the exhaust gas treatment steps involve absorbing the waste gas generated in the wet grinding step and the high-temperature digestion step through a gas absorption tower, and spraying the waste gas with an alkaline absorption liquid with a pH value of 10-13 in a three-stage countercurrent spraying manner to absorb and recover sulfur in the waste gas.

[0017] Furthermore, the flotation and hydrocyclone separation includes: conveying a slurry containing the first and second bottom slag to a microbubble flotation machine; then injecting a 30-100 μm bubble cluster into the slurry through an airlift microbubble generator system for gas-solid adsorption separation in the flotation cell; collecting the carbon powder-enriched foam layer formed on the surface of the flotation cell for dewatering; drying and packaging the dewatered carbon powder for recycling; inputting the bottom sludge from the microbubble flotation machine into a hydrocyclone, guiding the bottom sludge tangentially into a hydrocyclone separation system, and achieving liquid-solid separation using liquid rotation and centrifugal force; achieving solid-phase fractionation separation through density differences to obtain an underflow portion and an overflow portion; conveying the underflow portion to the flotation machine, sequentially adding a carboxylic acid collector and a polyether defoamer to the slurry; injecting a 20-80 μm bubble cluster through an airlift microbubble generator system, collecting the surface-enriched titanium dioxide foam layer, obtaining titanium dioxide product after dewatering and drying, and collecting and recovering barium sulfate from the flotation machine.

[0018] Furthermore, the wet leaching and stepwise precipitation process includes: reacting the overflow portion with the leachate to obtain the reacted leachate; adjusting the pH of the leachate to 4.0-5.0 to precipitate aluminum salts; separating the aluminum salts and then adjusting the pH to 9.5-10.5 to precipitate magnesium salts; and sending the third filtrate after magnesium salt separation to chemical precipitation treatment.

[0019] (III) Beneficial Effects

[0020] Compared with existing technologies, the recycling and treatment method and system for hazardous waste from fireworks and firecrackers of the present invention have the following advantages:

[0021] This invention designs a method and system for recycling and treating hazardous waste from fireworks and firecrackers. Through the synergistic effect of chemical precipitation, A2O biochemical treatment, Fenton oxidation, and BAF biological filter, it effectively removes perchlorate, heavy metals (such as barium, aluminum, and magnesium), and organic matter (COD) from wastewater, ensuring that the effluent meets the discharge standards of "DB43 / 3001-2024 Industrial Wastewater Perchlorate Pollutant Discharge Standard" and "GB 8978-1996 Integrated Wastewater Discharge Standard". Through flotation, cyclone separation, and stepwise sedimentation, carbon powder, titanium dioxide, barium sulfate, aluminum salts, and magnesium salts are recovered from the waste residue, improving the overall resource recovery rate. The waste residue (such as barium salt precipitate) of the wastewater system is used as raw material for the waste residue system, and the treated liquid (such as high-temperature digestion filtrate) of the waste residue system is returned to the wastewater system for recycling, realizing "waste treatment with waste" and reducing the overall treatment cost. Attached Figure Description

[0022] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0023] Figure 1 This is a flowchart illustrating the recycling and disposal method for hazardous waste from fireworks and firecrackers. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Example 1: As Figure 1As shown, this invention discloses a method for recycling and treating hazardous waste from fireworks and firecrackers, including: a wastewater treatment step: the wastewater treatment step includes a chemical precipitation step, an A2O biochemical treatment step, a Fenton oxidation step, and a BAF biological filter step to remove perchlorate, COD, and heavy metals; a waste residue treatment step: the waste residue treatment step includes a wet grinding step, a high-temperature digestion step, a flotation step, a hydrocyclone separation step, a wet leaching step, and a stepwise sedimentation step to recover carbon powder, titanium, barium, aluminum, and magnesium resources; a synergistic coupling mechanism: the bottom slag generated in the wastewater treatment step is transported to the waste residue treatment step for treatment, and the filtrate generated in the waste residue treatment step is transported to the wastewater treatment step for treatment. In this embodiment, the wastewater comes from the supernatant wastewater of the sedimentation tank of a fireworks and firecrackers enterprise, which contains barium salts and perchlorate. The waste residue comes from the bottom slag of the sedimentation tank of a fireworks and firecrackers enterprise, which contains various heavy metals, sulfur, and carbon powder. The supernatant wastewater of the sedimentation tank of the fireworks and firecrackers enterprise is first collected in a collection tank for convenient subsequent centralized treatment.

[0026] The collected wastewater is first treated through a chemical precipitation step. In this step, sulfate and an oxidant are added to the wastewater to treat barium ions, sulfur ions, and polysulfide ions in the water, forming sulfate precipitates. The sulfate is used as a precipitant, and it is at least one of sodium sulfate, potassium sulfate, potassium aluminum sulfate, or calcium sulfate. The oxidant is at least one of sodium hypochlorite, hydrogen peroxide, or ozone. The precipitate is then separated from the liquid phase to obtain a first filtrate and a first bottom residue. The first bottom residue is waste residue containing barium salts, and the first filtrate is wastewater containing perchlorate. The first filtrate is then treated sequentially through an A2O biochemical treatment step, a Fenton oxidation step, and a BAF biological filter step before being discharged. The A2O biochemical treatment step degrades pollutants (such as perchlorate) through a microbial membrane. The Fenton oxidation step catalyzes the generation of hydroxyl radicals to degrade recalcitrant organic matter. The BAF biological filter step performs denitrification and decarbonization treatment, and the treated water meets the discharge standards. The first bottom residue is then transported to a flotation step for further treatment.

[0027] The collected waste residue is first treated by wet grinding. The wet grinding step involves mixing the waste residue with a grinding aid, which is at least one of sodium hydroxide, sodium sulfate, calcium hydroxide, or calcium sulfate, to produce a slurry. The high-temperature digestion step involves mixing the slurry with an oxidant for a high-temperature digestion reaction. This high-temperature oxidation reaction converts sulfur and metal powder into corresponding soluble ionic substances. The oxidant is selected from at least one of concentrated nitric acid, hydrogen peroxide, and sodium hypochlorite. The reaction product undergoes solid-liquid separation to obtain a second filtrate and a second bottom residue. The second filtrate is then sent to a chemical precipitation step for further treatment. The flotation step… The process includes separating and recovering carbon powder from sludge containing a second bottom sludge using an airlift microbubble aeration method; the hydrocyclone separation step involves using hydrocyclone to perform solid-liquid separation on the bottom sludge from which carbon powder has been separated, resulting in an underflow portion and an overflow portion; the flotation step further includes separating and recovering barium sulfate and titanium dioxide from the underflow portion using a combination of airlift microbubbles and flotation reagents; the wet leaching step and the stepwise precipitation step involve reacting the overflow portion with the leachate, adding dilute acid after the reaction to precipitate aluminum salts first, adding dilute alkali after separating the aluminum salt precipitate to precipitate magnesium salts, and then sending the third filtrate after magnesium salt precipitation to the chemical precipitation step for further treatment.

[0028] It also includes an exhaust gas treatment step, which involves absorbing the waste gas generated by the wet grinding step and the high-temperature digestion step. The wet grinding step generates sulfide-containing dust, and the high-temperature digestion generates sulfur-containing waste gas. The waste gas is then sprayed with an alkaline absorption liquid to absorb and recover the sulfur in the waste gas.

[0029] Example 2: Figure 1 As shown, a recycling system applying the above-mentioned method for recycling and treating hazardous waste from fireworks and firecrackers includes: a wastewater treatment subsystem, comprising chemical precipitation, A2O biochemical treatment, Fenton oxidation, and BAF biological filter; and a waste residue treatment subsystem, comprising wet grinding, high-temperature digestion, flotation, hydrocyclone separation, wet leaching, and stepwise sedimentation. In this embodiment, the wastewater originates from the supernatant wastewater of the sedimentation tank of a fireworks and firecrackers enterprise, containing barium salts and perchlorates. The waste residue originates from the bottom sludge of the sedimentation tank of a fireworks and firecrackers enterprise, containing various heavy metals, sulfur, and carbon powder. The supernatant wastewater of the sedimentation tank of the fireworks and firecrackers enterprise is first collected in a collection tank for convenient subsequent centralized treatment.

[0030] The chemical precipitation process includes a stirred reaction tank and a solid-liquid separation device connected in sequence. The stirred reaction tank is equipped with a sulfate and oxidant dosing device. Wastewater from the collection tank is introduced into the stirred reaction tank for recycling and treatment. The stirred reaction tank also preferentially replenishes the second and third filtrates transported from the waste residue treatment plant. A 0.3-2% sulfate-containing solution and an oxidant-containing solution are added to the stirred reaction tank to treat barium ions, sulfur ions, and polysulfide ions in the water, forming a sulfate precipitate. The sulfate is at least one of sodium sulfate, potassium sulfate, potassium aluminum sulfate, or calcium sulfate, and its dosage is 1.1-1.5 times the total molar amount of barium ions. The oxidant is at least one of sodium hypochlorite, hydrogen peroxide, or ozone, and its dosage is based on the total molar amount of sulfur ions. The concentration is 1.5 to 2 times the standard concentration. The stirring reaction tank is stirred by a mechanical stirring device or a hydraulic stirring device. A pH online monitoring device is installed in the reaction tank to control the reaction pH to 8.5 to 11.0. The barium salt-containing waste residue is precipitated. The precipitate is separated from the liquid phase by a solid-liquid separation device to obtain the first filtrate and the first bottom residue. The solid-liquid separation device is selected from at least one of inclined tube sedimentation tank, centrifuge, or plate and frame filter press. In this embodiment, a filter press is used for separation. The operating pressure of the filter press is 0.4 to 0.8 MPa, the filtration time is 10 to 30 minutes, and the moisture content of the filter cake is controlled at 25% to 45%. The first bottom residue is transported to flotation for treatment. The first filtrate is discharged after sequentially undergoing A2O biochemical treatment, Fenton oxidation, and BAF biological filter treatment.

[0031] Main reaction equations in the stirred tank:

[0032] Ba 2+ + SO4 2− → BaSO4(s)↓

[0033] 3S 2− + 4ClO 4− + 16H + → 3SO4 2− + 4Cl − + 8H2O

[0034] The A2O biological treatment system comprises an anaerobic tank, an anoxic tank, an aerobic tank, and a sedimentation tank connected in sequence. Each of the anaerobic, anoxic, and aerobic tanks contains biological packing material with a functional microbial membrane attached to its surface. When the first filtrate flows through these tanks, pollutants are degraded through the biochemical action of the microbial membrane. The biological packing material is at least one of elastic three-dimensional packing material, combined fiber packing material, or suspended porous packing material, with a filling rate of 30% to 70% of the tank volume. Hydraulic stirring devices are installed in the anaerobic and anoxic tanks, and a microporous aeration device is installed at the bottom of the aerobic tank, with the aeration rate controlled at a dissolved oxygen concentration of 2.0 to 4.0 mg / L. A pretreatment unit is also included, connected to the anaerobic tank via a pipeline, for performing grid filtration and pH adjustment on the water entering the A2O biological treatment system. A mixed liquor return pipeline is provided between the sedimentation tank and the anoxic tank, with a return ratio of 50% to 200%; a sludge return pipeline is provided between the sedimentation tank and the anaerobic tank, with a return ratio of 30% to 100%, and the total retention time of A2O biochemical treatment is 8 to 24 hours.

[0035] Main reaction equations for A2O biochemical treatment:

[0036] 6NO3 − + 5CH3OH → 3N2↑ + 5CO2+ 7H2O + 6OH -

[0037] ClO4 − + 8H + +8e − → Cl − + 4H2O

[0038] 2HS − + 4O2→ 2SO4 2− + 2H +

[0039] 5HS − + 8NO3 − + 3H + → 5SO4 2− + 4N2↑+4H2O

[0040] Fenton oxidation comprises a Fenton reaction unit, a flocculation unit, and a precipitation unit connected in sequence; water treated by A2O biochemical treatment is transported to the Fenton reaction unit, where Fe is added... 2+ The H2O2 catalytic system initiates a hydroxyl radical oxidation reaction to degrade recalcitrant organic matter in wastewater. The influent is equipped with a multi-stage filtration system and an online ORP monitor to control the influent oxidation-reduction potential at 200-400 mV. The main body of the Fenton reaction unit is a multi-stage mechanical mixing reactor, internally containing Fe...2+ Online dosing device and H2O2 gradient injection pipeline to control Fe 2+ The molar ratio of ferrous salt to H2O2 is 1:5 to 1:15, and an automatic pH adjustment device is provided to maintain the pH value of the reaction zone at 2.0 to 4.0, with a reaction time of 30 to 120 minutes. The flocculation unit promotes the hydrolysis of ferrous salt to form flocs by adjusting the pH. The sedimentation unit achieves solid-liquid separation of the flocs from the treated water. The flocculation unit is equipped with an alkaline reagent dosing system to raise the pH of the wastewater to 8.0 to 9.5, and adds polyacrylamide flocculant at a dosage of 0.5 to 2.0 mg / L. The sedimentation unit is an inclined plate sedimentation tank or a high-efficiency clarifier, with a sludge thickening hopper and sludge discharge pump at the bottom.

[0041] The main reaction equation for Fenton oxidation is: ClO4 − + 8Fe 2+ + 8H + → Cl − + 8Fe 3+ + 4H2O

[0042] The water treated by Fenton oxidation is transported to a BAF biological filter. The BAF biological filter treatment system includes a denitrification-type DN-BAF tank and a decarbonization-type DC-BAF tank connected in series. The DN-BAF tank is set as a denitrification functional zone, with an anoxic environment and denitrifying bacteria enrichment packing material for removing total nitrogen (TN). The packing material is porous ceramsite or polyurethane-based modified packing material with a porosity of 60-85% and a specific surface area of ​​300-800 m² / m³. The DC-BAF tank is filled with volcanic rock or activated carbon composite packing material with a particle size of 3-8 mm and a filling height of 2.5-4.0 m. The DC-BAF tank is designed as an aerobic decarbonization zone, equipped with an aeration device and organic pollutant degradation packing material to remove COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand), and SS (Suspended Solids). It is equipped with a carbon source replenishment device to control the influent C / N ratio at 4:1 to 6:1. A rotary aerator is installed at the bottom of the DC-BAF tank, with an aeration intensity of 0.3 to 0.8 m³ / (m²·h), maintaining a dissolved oxygen concentration of 2.5 to 4.5 mg / L, and ensuring a hydraulic retention time greater than 8 hours. After sequential treatment by two stages of filters, the wastewater achieves synergistic deep denitrification and decarbonization. The treated water, after A2O biological treatment, Fenton oxidation, and BAF biological filter treatment, meets discharge standards.

[0043] The main reaction equation for the BAF biological filter is: ClO4 − + 8e − + 8H + → Cl + + 4H2O (microorganisms)

[0044] The waste residue is first ground using a wet grinding mill, which is equipped with a feeding system and a grinding aid mixing tank to assist in the operation of the wet grinding mill. The wet grinding includes: grinding the waste residue using the wet grinding mill; the feeding system injects the waste residue and grinding aid into the wet grinding mill in a preset ratio through a quantitative conveying module; the feeding system includes a raw material weighing module, an aid flow control, and a premixing tank; the premixing tank is equipped with a stirring device with a stirring speed of 30-90 rpm. The grinding aid is at least one of sodium hydroxide, sodium sulfate, calcium hydroxide, or calcium sulfate, and its addition amount is 0.5%-5.0% of the raw material mass; the reaction temperature is controlled at 30-80℃. The wet grinding mill has a speed adjustment range of 800-3000 rpm during mechanical grinding and has a built-in pH sensor to dynamically control the pH value of the slurry within the range of 10.0-12.0 according to the grinding process.

[0045] The main reaction equation for wet grinding is: 3S + 6OH⁻ − → 2SO3 2− + 3H2O + S 2−

[0046] The slurry produced by grinding is transported to a high-temperature digestion vessel for high-temperature digestion. The high-temperature digestion includes: putting the slurry produced by wet grinding into the high-temperature digestion vessel; adding 1-10% oxidant to the high-temperature digestion vessel; raising the temperature of the high-temperature digestion vessel to 80-150°C; maintaining the reaction pressure in the range of 0.1-0.5 MPa; and the reaction time is 30-120 minutes. The oxidizing agent is selected from at least one of concentrated nitric acid, hydrogen peroxide, and sodium hypochlorite, with a mass concentration of 10% to 50%. Through a high-temperature oxidation reaction, sulfur and metal powder are converted into corresponding soluble ionic substances. During the reaction stage in the high-temperature digestion vessel, a stepped heating method is used: pre-oxidation at 60-100℃ for 10-20 minutes, followed by heating to the target temperature at 3-5℃ / min. After the reaction, the cooling rate is controlled by a stepped cooling method: first cooling to 100℃ at 2-3℃ / min, then naturally cooling to below 80℃. The exhaust valve is then opened, and after the gas is released, the material is discharged to a filter press. Solid-liquid separation is performed in the filter press to obtain a second filtrate and a second bottom slag. The second filtrate is then transported to a chemical precipitation tank for treatment. Specifically, it is transported to a stirred reaction tank for treatment. The operating pressure of the filter press is 0.4-0.8 MPa, the filtration time is 10-30 minutes, and the moisture content of the filter cake is controlled at 25%-45%.

[0047] Main reaction equations for the high-temperature digestion reactor:

[0048] S + 3H2O2+ Ca(OH)2 → CaSO4+ 4H2O

[0049] C + 2H₂O₂ → CO₂ + 2H₂O

[0050] CO2 + Ca(OH)2 → CaCO3 + H2O

[0051] Cu(OH)₂ → CuO + H₂O

[0052] CuO + H2O2 → Cu 2+ + O2 + 2OH −

[0053] It also includes exhaust gas treatment, wherein the exhaust gas treatment step involves absorbing the waste gas generated in the wet grinding step and the high-temperature digestion step through a gas absorption tower. The wet grinding step generates sulfide-containing dust, and the high-temperature digestion generates sulfur-containing waste gas. The waste gas is absorbed by the gas absorption tower, and the waste gas drawn into the tower is sprayed with an alkaline absorbent liquid with a pH value of 10-13 in a three-stage countercurrent spraying manner, so that the sulfur-containing gas and the absorbent liquid undergo a neutralization reaction, and the sulfur in the waste gas is absorbed and recovered. The alkaline absorbent liquid contains a sodium hydroxide solution with a mass fraction of 5%-32%, the spray density is controlled at 8-15 m³ / (m²·h), and the gas-liquid volume ratio is 100:1-300:1.

[0054] The flotation and hydrocyclone separation process includes: conveying a slurry containing the first and second bottom slags to a microbubble flotation machine; using an airlift microbubble aeration method to separate and recover carbon powder from the slurry; first, conditioning the slurry to a solid content of 10%~25%; conditioning includes adding 0.01%~0.1% (w / w) of seed crystals to the slurry and controlling the slurry temperature within the range of 25~45℃; then injecting a 30~100μm bubble cluster into the slurry through an airlift microbubble generation system, with the gas flow rate controlled at 0. 0.5~3.0 m3 / (m2 / min); gas-solid adsorption separation is carried out in the flotation cell, maintaining a stirring intensity of 200~400 rpm and a flotation time of 10~30 minutes; the carbon powder enriched foam layer formed on the surface of the flotation cell is collected and dehydrated; the dehydrated carbon powder is dried to a moisture content ≤5% and then packaged for recycling. The working gas of the microbubble generation system is selected from compressed air, nitrogen, or a mixture of both, and the gas pressure is maintained at 0.15~0.35 MPa; the bottom sediment in the microbubble flotation machine is fed into a hydrocyclone, utilizing the rotational flow of the liquid and separation... The process achieves liquid-solid separation by pre-treating the input sediment. Sediment pre-treatment includes adjusting the solid content to 15%–30%; controlling the slurry density within the range of 1.2–1.6 g / cm³; tangentially introducing the slurry into the hydrocyclone separation system at a flow rate of 3–8 m / s; achieving solid-phase fractional separation through density differences; and collecting the underflow and overflow slurries for further processing. The separation process employs multi-stage cyclones in series to improve separation efficiency. The underflow portion is then fed into a flotation machine, where airlift microbubbles combined with flotation reagents are used to separate carbon dioxide. Titanium dioxide is separated and recycled from the underflow. The underflow slurry is also treated with soil to adjust the solids content to 15%–35% and control the pH to 6.0–8.5. A carboxylic acid collector with a mass concentration of 50–150 ppm and a polyether-type defoamer with a mass concentration of 20–80 ppm are added sequentially to the slurry. A 20–80 μm bubble cluster is injected through an airlift microbubble generator system, with the gas flux controlled at 0.8–2.5 m³ / (m²·h). The surface-enriched titanium dioxide foam layer is collected, and after dehydration and drying, a titanium dioxide product with a purity ≥95% is obtained. The microbubble generator system uses a mixture of compressed air and nitrogen in a ratio of 3:1–5:1, with the gas pressure stabilized at 0.2–0.4 MPa. Barium sulfate in the flotation machine is then collected and recovered.

[0055] Furthermore, the wet leaching and stepwise precipitation process includes: the overflow portion is an aluminum-magnesium slurry, which reacts with the leachate, controlling the liquid-solid ratio at 3:1 to 8:1, the temperature at 60 to 90°C, and the leaching time at 1 to 4 hours to obtain a leachate containing aluminum and magnesium ions. The leachate is a 5% to 20% sulfuric acid solution or hydrochloric acid solution. A dilute alkali is added to the leachate to adjust the pH to 4.0 to 5.0, and the mixture is stirred for 30 to 60 minutes to allow aluminum salts to precipitate preferentially. After separating the aluminum salt precipitate, a dilute alkali is added to the remaining solution to adjust the pH to 9.5 to 10.5, and the mixture is stirred for 20 to 40 minutes to allow magnesium salts to precipitate selectively. The dilute alkali is a 20% to 50% sodium hydroxide solution or potassium hydroxide solution, thereby recovering and utilizing aluminum and magnesium. The third filtrate after precipitation separation is sent to a chemical precipitation treatment for recycling.

[0056] The main reaction equations for wet leaching and stepwise precipitation are as follows:

[0057] Al2(SO4)3+ 6NaOH → 2Al(OH)3↓ + 3Na2SO4 (at pH ≈ 6)

[0058] MgSO4+ 2NaOH → Mg(OH)2↓ + Na2SO4 (pH ≈ 9–10)

[0059] CuSO4+ 2NaOH → Cu(OH)2↓ + Na2SO4

[0060] Example 3: Example 3 is a specific example. The chemical precipitation process is equipped with a stirred reaction tank and a solid-liquid separation device connected in sequence. The stirred reaction tank is equipped with a sulfate and oxidant dosing device. Wastewater in the collection tank is introduced into the stirred reaction tank for recycling and treatment. The stirred reaction tank is preferentially supplemented with the second and third filtrates transported by the waste residue treatment. 0.5% sodium sulfate solution and oxidant solution are added to the stirred reaction tank and reacted for 30 minutes. At this time, the pH value is 9.2. Then, solid-liquid separation is performed to obtain the first filtrate and the first filter residue.

[0061] The first filtrate is placed in an A2O reactor with a 50% filling rate of combined fiber packing. The reflux ratio between the sedimentation tank and the anoxic tank is controlled at about 120%, and the reflux ratio between the sedimentation tank and the anaerobic tank is controlled at 70%. The dissolved oxygen concentration in the aerobic tank is controlled between 3.0 and 3.5 mg / L through aeration. A sludge return pipeline is provided between the sedimentation tank and the anaerobic tank, with a reflux ratio of 30% to 100%. The total retention time is 8 to 24 hours. The first treated filtrate is obtained after the reaction.

[0062] The oxidation-reduction potential of the first-treatment filtrate is 293 mV. The Fenton reaction is carried out at a pH of about 3.2 for 60 min, with a molar ratio of Fe2+ to H2O2 of 1:10. After the reaction is completed, the pH is adjusted to 8.3, 1 mg / L of polyacrylamide is added, and then the mixture is separated into solid and liquid by a plate sedimentation tank to obtain sludge at the bottom of the tank and the second-treatment filtrate.

[0063] The second-treated filtrate was retained for 12 hours in a secondary biological filter with porous ceramic granules having a porosity of 65%, with an aeration rate of 0.4 m³ / (m²·h) and a dissolved oxygen concentration maintained at approximately 2.9 mg / L, yielding the third-treated filtrate. Testing revealed that the concentration of perchlorate, a characteristic pollutant in the third-treated filtrate, was 0.08 mg / L, far below the emission limit requirements of the "DB43 / 3001-2024 Industrial Wastewater Perchlorate Pollutant Discharge Standard." The COD concentration was 42 mg / L, and the concentrations of other heavy metal ions all met the requirements of the "GB8978-1996 Integrated Wastewater Discharge Standard."

[0064] The bottom slag from the sedimentation tank of a fireworks and firecracker factory is placed in a mixer, along with 20% by mass of the third-treatment filtrate and 3.2% by mass of calcium hydroxide. The mixture is stirred at 80 rpm for 30 minutes, then fed into a wet grinder at approximately 1350 rpm. After grinding, a slurry is obtained with a pH of 11.87. Utilizing the third-treatment filtrate for wet grinding achieves "waste-to-waste treatment," reducing overall treatment costs.

[0065] The slurry is put into a high-temperature digestion vessel, 6.4% hydrogen peroxide is added, and it is pre-oxidized in the range of 60~100℃ for 10 minutes. Then, the temperature is increased to 130℃ at a rate of 5℃ / min and reacted for 30 minutes. After the reaction is completed, it is first cooled to 100℃ at a rate of 3℃ / min, and then naturally cooled to below 80℃. The exhaust valve is opened, and the material is discharged after the gas is absorbed, thus obtaining the slurry after high-temperature digestion.

[0066] The waste gas generated during wet grinding and high-temperature digestion is absorbed and treated in an absorption tower with a 32% sodium hydroxide solution. The spray density of the absorption tower is 9.3 m³ / (m²·h).

[0067] After high-temperature digestion, the sludge undergoes solid-liquid separation using a filter press, yielding a second filtrate and a second bottom residue. The second filtrate is returned to the stirred reaction tank in the wastewater treatment section for further processing. The first bottom residue and the second filter residue are mixed, and the third-treatment filtrate is added to condition the sludge to a solids content of approximately 20%. The third-treatment filtrate is then used for conditioning, achieving "waste-to-waste treatment," which can reduce overall treatment costs.

[0068] Then it enters the flotation machine process. Compressed air of 0.22 MPa is added to the flotation unit and the gas flow rate is controlled at 0.9 m3 / (m2 / min) for flotation. The total flotation time is 30 min. The carbon powder foam layer formed on the surface of the flotation cell is collected and filtered to obtain carbon mud product with a water content of 56%.

[0069] The sediment from the microbubble flotation machine is fed into a hydrocyclone with a slurry concentration of approximately 18%. 0.08% barium sulfate fine powder is added. The slurry is flowed at a velocity of 3–8 m / s and subjected to hydrocyclone separation at 35°C. The underflow portion of the slurry is obtained from the bottom of the secondary hydrocyclone. The overflow portion of the slurry is obtained by mixing the liquids from the primary and secondary hydrocyclone outlets. This underflow portion is then subjected to flotation separation in the flotation machine. During flotation, 120 ppm of salicylic acid and 50 ppm of polypropylene glycol are added, and the gas flow rate is controlled at 1.2 m³ / (m²·h). Barium sulfate and titanium dioxide slurries are separated and filtered to obtain the corresponding products.

[0070] Add 20% sulfuric acid to the overflow slurry, control the acidity at 1.2 mol / L, control the liquid-solid ratio at 4:1, leach at 70℃ for 2 hours to obtain a leachate containing aluminum and magnesium ions. Then adjust the pH to 4.0~5.0 with 32% liquid alkali, react for 30 min, filter to obtain aluminum salt precipitate, then continue to add liquid alkali to adjust the pH to 10, stir and react for 30 min to obtain magnesium salt precipitate. After solid-liquid separation, obtain the third filtrate, return the third filtrate to the stirred reaction tank for further treatment.

Claims

1. A method for recycling and disposing of hazardous waste from fireworks and firecrackers, characterized in that, include: Wastewater treatment steps: The wastewater treatment steps sequentially include a chemical precipitation step, an A2O biochemical treatment step, a Fenton oxidation step, and a BAF biological filter step to remove perchlorate, COD, and heavy metals; In the chemical precipitation step, sulfate and oxidant are added to the wastewater to form sulfate precipitate, and then the precipitate is separated from the liquid phase to obtain a first filtrate and a first bottom sludge. The first filtrate is discharged after being treated sequentially through the A2O biochemical treatment step, the Fenton oxidation step, and the BAF biological filter step; Waste residue treatment steps: The waste residue treatment steps include wet grinding, high-temperature digestion, flotation, hydrocyclone separation, wet leaching and stepwise sedimentation. The product obtained from the high-temperature digestion step is separated into solid and liquid to obtain a second filtrate and a second bottom residue. The second bottom residue is then subjected to flotation, hydrocyclone separation, wet leaching and stepwise sedimentation to recover carbon powder, titanium, barium, aluminum and magnesium resources. Synergistic coupling mechanism: The first bottom slag generated in the wastewater treatment step is transported to the flotation step in the waste residue treatment step, and the second filtrate generated in the waste residue treatment step is transported to the wastewater treatment step for treatment.

2. The method for recycling and disposing of hazardous waste from fireworks and firecrackers according to claim 1, characterized in that, The wet grinding step involves mixing waste residue and grinding aids to produce slurry through wet grinding; The high-temperature digestion step involves mixing the mud and oxidant to carry out a high-temperature digestion reaction. The product after the reaction is separated into solid and liquid to obtain a second filtrate and a second bottom slag. The second filtrate is then sent to a chemical precipitation step for further treatment. The flotation step includes separating and recovering carbon powder from the slurry containing the second bottom slag by airlift microbubble aeration. The hydrocyclone separation step involves using hydrocyclone to perform solid-liquid separation on the sediment from which carbon powder has been separated, resulting in an underflow portion and an overflow portion. The flotation step also includes separating and recovering barium sulfate and titanium dioxide from the underflow by using airlift microbubbles in combination with flotation reagents; The wet leaching step and the stepwise precipitation step involve reacting the overflow portion with the leachate, adding dilute acid after the reaction to precipitate the aluminum salt first, adding dilute alkali after separating the aluminum salt precipitate to precipitate the magnesium salt, and then sending the third filtrate after separating the magnesium salt precipitate to the chemical precipitation step for further processing.

3. The method for recycling and disposing of hazardous waste from fireworks and firecrackers according to claim 2, characterized in that, It also includes an exhaust gas treatment step, which involves absorbing the waste gas generated by the wet grinding step and the high-temperature digestion step, and spraying the waste gas with an alkaline absorption liquid to absorb and recover sulfur from the waste gas.

4. A recycling system for hazardous waste from fireworks and firecrackers according to any one of claims 1 to 3, characterized in that, include: Wastewater treatment subsystem: The wastewater treatment subsystem includes chemical precipitation, A2O biochemical treatment, Fenton oxidation, and BAF biological filter; Waste residue treatment subsystem: The waste residue treatment subsystem includes wet grinding, high-temperature digestion, flotation, hydrocyclone separation, wet leaching and stepwise sedimentation.

5. The recycling system according to claim 4, characterized in that, The chemical precipitation process involves treating wastewater in a stirred reaction tank by adding sulfate and oxidant to the wastewater; controlling the reaction pH to 8.5~11.0 to precipitate barium salt-containing waste residue; and separating the precipitate from the liquid phase using a solid-liquid separation device to obtain a first filtrate and a first bottom residue, with the first bottom residue being transported to flotation for further treatment. The first filtrate is discharged after sequentially undergoing A2O biochemical treatment, Fenton oxidation, and BAF biological filter treatment.

6. The recycling system according to claim 5, characterized in that, The wet grinding includes: The waste residue is ground using a wet grinding mill, and grinding aids are added to the wet grinding mill. The pH of the slurry formed during grinding should be controlled to be 10.0~12.0; The high-temperature digestion includes: The slurry produced by wet grinding is put into a high-temperature digestion reactor; Add an oxidant to the high-temperature digestion vessel and heat the high-temperature digestion vessel to 80~150℃; During the heating process, a stepped heating method is adopted: pre-oxidation at 60~100℃ for 10~20 minutes, then heating to the target temperature at 3~5℃ / min. After the reaction is completed, the cooling rate is controlled by a stepped cooling method, first cooling to 100℃ at 2~3℃ / min, then naturally cooling to below 80℃ before discharging to a filter press. Solid-liquid separation is carried out through the filter press to obtain the second filtrate and the second bottom residue. The second filtrate is then sent to a chemical precipitation treatment.

7. The recycling system according to claim 6, characterized in that, It also includes exhaust gas treatment, wherein the exhaust gas treatment steps involve absorbing the waste gas generated by the wet grinding step and the high-temperature digestion step through a gas absorption tower, and spraying the waste gas with an alkaline absorption liquid with a pH value of 10-13 in a three-stage countercurrent spraying manner to absorb and recover sulfur in the waste gas.

8. The recycling system according to claim 6, characterized in that, The flotation and hydrocyclone separation includes: The slurry containing the first and second bottom slags is fed into a microbubble flotation machine; Then, a group of bubbles of 30~100μm is injected into the slurry through an airlift microbubble generation system, and gas-solid adsorption separation is carried out in the flotation cell; the carbon powder enriched foam layer formed on the surface of the flotation cell is collected and dehydrated; the dehydrated carbon powder is dried and packaged for recycling. The sediment in the microbubble flotation machine is fed into a hydrocyclone and guided tangentially into the hydrocyclone separation system. Liquid-solid separation is achieved by the rotational flow of the liquid and centrifugal force. Solid phase separation is achieved by density difference to obtain the underflow and overflow portions. The underflow portion is fed into the flotation machine, where a carboxylic acid collector and a polyether defoamer are added sequentially to the slurry. A bubble cluster of 20-80 μm is injected through an airlift microbubble generation system, and the surface-enriched titanium dioxide foam layer is collected. After dehydration and drying, titanium dioxide product is obtained, and barium sulfate in the flotation machine is collected and recovered.

9. The recycling system according to claim 8, characterized in that, The wet leaching and stepwise precipitation include: The overflow portion reacts with the leachate to obtain the reacted leachate. The pH of the leachate is adjusted to 4.0~5.0 to precipitate aluminum salts. After separating the aluminum salts, the pH is adjusted to 9.5~10.5 to precipitate magnesium salts. The third filtrate after magnesium salt separation is sent to chemical precipitation treatment.

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