Rapid detoxification and resource utilization method of waste incineration fly ash based on Joule heat

Abstract

The present invention relates to hazardous waste treatment technology, and aims to provide a method for rapid detoxification and resource utilization of fly ash from garbage incineration based on Joule heat. The method mainly includes: fly ash acid washing and reduction, fly ash material compatibility, Joule heat efficient detoxification, heavy metal recovery, and preparation of high-performance gelling materials of activated fly ash. Compared with the prior art, the present invention utilizes the Joule heat principle to extract heavy metals and degrade dioxins through the heat energy generated by the self-exothermic heat inside the fly ash material, with low energy consumption and no secondary pollution during the disposal process; the heavy metal extraction efficiency is high, and the collected particles have a high concentration of heavy metals, which greatly reduces the subsequent smelting and purification costs of heavy metals; the heavy metals are separated from the fly ash, and the regeneration of dioxins is avoided, while the pollution problems of heavy metals and dioxins in the fly ash are completely solved; the obtained fly ash after disposal has a high resource utilization value, simple process steps, low cost, and low carbon and environmental protection.

Description

Technical Field

[0001] The invention relates to a hazardous waste treatment technology, in particular to a method for rapid detoxification and resource utilization of waste incineration fly ash based on Joule heat, and belongs to the technical field of harmless treatment and resource utilization of waste incineration fly ash. Background Art

[0002] Municipal solid waste incineration technology plays an important role in the harmless treatment process, but waste incineration fly ash is rich in heavy metals (lead, zinc, chromium, cadmium, nickel, selenium, etc.), organic pollutants (dioxin, etc.), chloride salts, etc., and is a hazardous waste. In the past, the disposal was mainly based on cement / chelating agent solidification landfill. In recent years, with the promotion of waste-free city construction, fly ash also contains rich calcium, chlorine, silicon, metals, etc., and has resource attributes, so the resource recycling of fly ash has received extensive attention.

[0003] High-temperature thermal treatment technology for waste incineration fly ash is considered to be an efficient means of fly ash resource disposal, which can simultaneously solve the problems of heavy metal and dioxin pollution. However, high-temperature thermal treatment has problems such as high energy consumption, serious flue gas pollution, ineffective recovery of heavy metals, and dioxin regeneration. For example, the Chinese invention patent "A system for the coordinated recovery of non-ferrous metals from fly ash and slag from domestic waste incineration" (CN202022974595) introduces a method for high-temperature melting to recover Zn, Pb and Cd from waste incineration fly ash. This method sets a condensing device in the flue gas treatment system to recover solid particulate matter in the flue gas, thereby enriching a large amount of heavy metals. However, this method uses electric melting for heat treatment, which has high energy consumption and the recovered solid heavy metal content is low.

[0004] Therefore, in view of the shortcomings of existing fly ash resource disposal methods, an efficient, low-energy consumption, environmentally friendly fly ash high-temperature detoxification, heavy metal recovery and resource disposal method is proposed, which is of great practical application value. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for rapid detoxification and resource utilization of waste incineration fly ash based on Joule heat.

[0006] In order to solve the technical problem, the solution of the present invention is:

[0007] A method for rapid detoxification and resource utilization of waste incineration fly ash based on Joule heat is provided, comprising the following steps:

[0008] (1) After the waste incineration fly ash is pickled, the pickling mixed solution is separated into solid and liquid, and the solid is dried to obtain pickled fly ash and pickling liquid;

[0009] (2) adding sodium carbonate to the pickling solution for hardness removal, and then mechanically compressing, evaporating and crystallizing to obtain potassium chloride and sodium chloride;

[0010] (3) weighing the pickling fly ash, the sodium chloride obtained in step (2), and the petroleum coke in a mass ratio of 40-50:25-35:20-30, adding the mixture into a ball mill for mechanical ball milling; compressing the obtained mixed powder so that the resistance value of the compressed material is between 1 and 3Ω;

[0011] (4) placing the compressed material in the Joule heat generating section of the Joule heat flash evaporation device, setting the voltage to 120V to 180V, the treatment time to 1 to 3 seconds, the temperature to above 3000°C, and the number of discharges to 5 to 10 times; after high-temperature discharge treatment, the heavy metal-rich steam is condensed and collected to obtain heavy metal condensed particles; at the same time, the dioxins contained in the compressed material are degraded under high temperature conditions, and the petroleum coke is converted into graphene, and finally a detoxified activated fly ash is obtained;

[0012] (5) using hydrochloric acid solution to dissolve heavy metal condensed particles to obtain heavy metal chloride solution; adding sodium sulfide thereto to convert all heavy metal ions into sulfide precipitates; after filtering, collecting and drying, sending the sulfide to the lead-zinc ore metallurgical process for metal purification;

[0013] (6) washing the detoxified activated fly ash with water, and after solid-liquid separation, drying the solid to obtain desalted detoxified activated fly ash; subjecting the washing liquid to steam mechanical recompression evaporation crystallization, recovering the obtained sodium chloride and reusing it in step (3) for material matching;

[0014] (7) Desalted and detoxified activated fly ash, cement clinker and waste incinerator slag are weighed in a mass ratio of 20-30:40-50:20-40; then, the three materials are mixed with water at a water-cement ratio of 0.3-0.4 L / kg to obtain cement slurry, which is used to prepare cement slurry blocks.

[0015] As a preferred embodiment of the present invention, in the step (1), 1-2 mol / L hydrochloric acid solution is added at a liquid-to-solid ratio of 3-5:1 L / kg to carry out pickling treatment on the waste incineration fly ash; stirring is continued during the pickling process, and the change in the pH value of the pickling solution is monitored until it stabilizes in the range of 9-10, and then stirring is stopped to end the pickling.

[0016] As a preferred embodiment of the present invention, in the step (1), a filter press is selected for solid-liquid separation of the pickling mixed solution, and a drying condition is selected at 105° C. for 24 hours.

[0017] As a preferred embodiment of the present invention, in the step (2), when the pickling solution is subjected to a hardness removal treatment, the calcium ion concentration in the pickling solution is ultimately controlled to be below 100 mg / L.

[0018] As a preferred embodiment of the present invention, in step (3), the ball mill is a planetary ball mill, and the speed is set at 400 to 600 rpm during the ball milling process for 1 to 2 hours.

[0019] As a preferred embodiment of the present invention, in step (4), ice water bath or liquid nitrogen condensation is used for condensation collection; the main components of the heavy metal condensate particles are chlorides of zinc, lead, copper, cadmium and nickel, and also contain heavy metal oxides.

[0020] As a preferred embodiment of the present invention, in the step (5), the concentration of the hydrochloric acid solution used to dissolve the heavy metal condensed particles is 0.1-0.2 mol / L, and the added amount is controlled to be a liquid-to-solid ratio of 5-10:1 L / kg; the sulfides include zinc sulfide, lead sulfide, copper sulfide, cadmium sulfide and nickel sulfide.

[0021] As a preferred embodiment of the present invention, in the step (6), a filter press is selected for solid-liquid separation, and a drying temperature of 105° C. and drying for 24 hours are selected as the drying condition.

[0022] As a preferred embodiment of the present invention, in the step (7), the operation of preparing the cement slurry block includes: filling the cement slurry into a cement block mold and vibrating it, placing it in a steam curing box and curing it for 1 day before demoulding; then continuing steam curing for 27 days to finally obtain a cement slurry block with a compressive strength greater than 50 MPa.

[0023] Description of the invention principle:

[0024] Joule heat flash technology is based on the principle of Joule heat effect. It uses electric current pulses to pass through conductive samples to cause high-temperature reactions. It is mostly used in the preparation of nano-carbon materials and catalysts. Waste incineration fly ash has complex components, contains many calcium high-boiling point components, is non-conductive, and contains a variety of toxic and polluting components. The existing Joule heat process is difficult to directly use for fly ash disposal, so there has been no report on the successful treatment of waste incineration fly ash.

[0025] The present invention innovatively adopts Joule heat technology to perform multi-stage pretreatment of fly ash in view of the complex component characteristics of fly ash, and recover chloride salts and calcium carbonate. According to the basic conductivity requirements of Joule heat technology for materials and the purpose of achieving the volatilization of heavy metals in fly ash, the fly ash materials are targetedly matched and the fly ash is subjected to Joule heat high-temperature treatment. In addition, according to the characteristics of the fly ash after Joule heat treatment, subsequent treatment is carried out, and the fly ash after high-temperature activation is used as an active cementitious material to prepare high-performance solid waste-based cement, ultimately achieving fly ash detoxification, resource recovery and high-value utilization. The specific technical principles are as follows:

[0026] (1) Fly ash pickling reduction:

[0027] A large amount of soluble chloride salts (sodium chloride, potassium chloride) and calcium-containing acid-soluble components (calcium hydroxide and calcium carbonate) in fly ash are removed by pickling, so that the fly ash is reduced by more than 50%. Since the calcium-containing components have high resistance and high vapor pressure, removing most of the calcium-containing components by pickling is beneficial to the subsequent Joule heat treatment of fly ash. By adjusting the pH of the pickling solution within the range of 9 to 10, the fly ash is reduced to the maximum extent while the heavy metal release is minimized, and more than 99% remains in the solid phase of the fly ash, which not only reduces the heavy metal pollution in the wastewater, but also facilitates the subsequent high-temperature volatilization of heavy metals. The pickling solution after the fly ash is pickled is rich in calcium chloride, sodium chloride and potassium chloride inorganic salt components. After decalcification / magnesium de-hardening, it enters the MVR system, and sodium chloride and potassium chloride are obtained by evaporation and crystallization. Potassium chloride has a higher market price and can be sold directly, and sodium chloride can be used as an inorganic halogenating agent in the material matching process before Joule heat treatment, thereby avoiding the use of expensive chlorinating agents or iodizing agents.

[0028] (2) Fly ash material compatibility:

[0029] The remaining components of fly ash after pickling are mainly calcium sulfate, silicon dioxide, aluminum oxide and activated carbon. Although its conductivity is improved compared with the original fly ash, it is still necessary to add conductive materials to regulate its resistance during the Joule heat treatment process. Compared with the commonly used conductive additive carbon black powder, the present invention selects petroleum coke, which is regarded as industrial tailings, as a conductive material, which is cheaper. The appropriate amount of petroleum coke can not only adjust the resistance of the material, so that the material emits a large amount of heat during the flash Joule heat process, and the temperature reaches above 3000°C, but also can provide graphene raw materials for subsequent cement preparation. When there is too little petroleum coke, the material resistance is too large, the current passing through the material is small, and a large amount of heat cannot be generated; when there is too much petroleum coke, the resistance is too small, the Joule heat is too low, and the petroleum coke consumption is too large, and the fly ash disposal amount is reduced. In addition, the sodium chloride obtained in the pickling liquid after the fly ash is pickled is selected as a halogen additive and added to the fly ash, and the fly ash, petroleum coke and sodium chloride are fully ball-milled and mixed at high speed by mechanical ball milling. During the mechanical ball milling process, petroleum coke is fully contacted and mixed with non-conductive fly ash and sodium chloride, so that the materials can heat evenly during the Joule heat process. Under the condition of high-speed collision between sodium chloride and fly ash to generate a large amount of internal energy, chloride ions and a large amount of heavy metals (Pb, Zn, Cd, Ni, Cu, etc.) in the fly ash are halogenated, and the heavy metals are transformed from the non-volatile oxidation state to the low-boiling point volatile chloride form, which is conducive to the removal of heavy metals in the Joule heat process. In addition, during the mechanical ball milling process, dioxins adsorbed in the fly ash particles are destroyed or exposed in small amounts, which is conducive to the full high-temperature degradation of dioxins during the Joule heat treatment process. Therefore, through appropriate compatibility and mechanical ball milling, the optimal working conditions of fly ash Joule heat and the subsequent resource utilization of materials can be achieved.

[0030] (3) Joule heat efficient detoxification and heavy metal recovery:

[0031] Put the reasonably matched materials into the flash Joule heat device, adjust the resistance of the Joule heat generating section within the range of 1 to 3Ω by compressing the materials, and set the flash Joule heat voltage between 120V and 180V to avoid the breakdown of the device due to excessive current caused by too small resistance, and to avoid the Joule heat generated by too small current caused by too large resistance that cannot meet the disposal requirements. Set the flash Joule heat duration to 1 to 3 seconds. On the one hand, choosing a short Joule heat treatment of 1 to 3 seconds can save energy consumption. On the other hand, the material cools down quickly after power failure to avoid the rearrangement of the generated graphene to form a multi-layer carbon structure. Due to the high content of heavy metals in fly ash, multiple flash treatments are used. Most heavy metals have a boiling point below 3000℃, especially heavy metals after chlorination, with a boiling point below 1000℃. Therefore, most heavy metals can volatilize at high temperatures after multiple flash Joule heat treatments above 3000℃. The use of nitrogen condensation or ice water condensation, on the one hand, condenses the high-temperature vapor of heavy metals, which is conducive to the collection of heavy metal particles. On the other hand, rapid cooling avoids the resynthesis of dioxins degraded by high temperature, completely eliminating the problem of dioxin pollution. The heavy metals in the heavy metal condensate particles collected after flash Joule heat treatment mainly include zinc, lead, copper, cadmium, and nickel, and exist in the form of chlorides and a small amount of oxides. Through appropriate hydrochloric acid leaching, it is easy to extract a solution rich in the above heavy metals. Sodium sulfide is added to the above heavy metal solution. Since the sulfide forms of heavy metals such as zinc, lead, copper, cadmium, and nickel are difficult / insoluble, the heavy metal ions are converted into sulfide precipitation and recovered. The zinc and lead content in the recovered heavy metal solids accounts for more than 90%, which can be entered into the lead-zinc ore smelting process to further purify the metals.

[0032] (4) Preparation of high-performance cementitious materials from activated fly ash:

[0033] The silicon-calcium-aluminum components in fly ash are activated by high temperatures above 3000°C to generate active gelling components such as calcium silicate and calcium aluminosilicate. Since the silicon-calcium-aluminum components in fly ash have high volcanic ash activity after activation, reducing the amount of cement clinker can also achieve high mechanical strength. During the flash Joule heat treatment of petroleum coke, the instantaneous temperature rise weakens the van der Waals force between carbon atoms in petroleum coke, thermal vibrations occur in carbon atoms, the layered structure gradually dissociates, the bonds between carbon atoms break, and free carbon atoms are formed. In addition, due to the rapid cooling during the treatment process, the free carbon atoms are prevented from reforming into a multilayer carbon structure, and finally exist in the form of a single-layer graphene structure. The graphene component in the activated fly ash has a high specific surface area and a unique two-dimensional structure, and can be evenly dispersed in cement-based materials. This dispersion effect helps to improve the uniformity and fluidity of cement paste, thereby improving its workability and final mechanical properties. Graphene can serve as a crystal nucleus for the formation of cement hydration products, promote the hydration process, and can improve the microstructure of cement materials, reduce porosity, and increase density. Graphene forms a good interface with cement hydration products, effectively transferring stress, thereby improving the compressive and tensile strength of the material. In addition, before activated fly ash is used to replace part of cement clinker to prepare cementitious materials, the sodium chloride in the material is washed with water and evaporated and crystallized to avoid the negative impact of chloride salts on the cement hydration process. The rational combination of activated fly ash, cement clinker and waste incinerator slag can greatly reduce the amount of cement clinker while ensuring the high mechanical properties of cement-based products.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The method of the present invention utilizes the Joule heat principle to extract heavy metals and degrade dioxins through the heat energy generated by the self-exothermic heat inside the fly ash material, with low energy consumption and no secondary pollution during the disposal process;

[0036] (2) The method of the present invention has high heavy metal extraction efficiency, and the collected particles have high heavy metal concentration, which greatly reduces the subsequent smelting and purification costs of heavy metals;

[0037] (3) The method of the present invention separates heavy metals from fly ash and avoids dioxin regeneration, thereby completely solving the pollution problem of heavy metals and dioxins in fly ash.

[0038] (4) The fly ash obtained by the method of the present invention has a high resource utilization value, simple process steps, low cost, low carbon and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a process flow chart of the fly ash Joule heat treatment method and building material utilization;

[0040] Figure 2It is a simplified process schematic diagram of the Joule heat flash evaporation device in the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0042] In each embodiment, the waste incineration fly ash is selected from a waste incineration plant in Zhejiang, and the heavy metal content of the fly ash and the heavy metal leaching concentration under the HJ / T 557-2010 standard are shown in Table 1. The total dioxin toxicity equivalent of the original fly ash is 185ng-TEQ / kg.

[0043] Table 1 Heavy metal content and leaching concentration of raw waste incineration fly ash

[0044]

[0045] ND: Not Detected

[0046] The Joule heat flash evaporation device in the present invention adopts the existing technology without special requirements. The operating parameters in the reaction process are adjusted, and an ice water bath or liquid nitrogen condensation is used for condensation collection. The heavy metal condensate particles obtained by condensation collection are mainly composed of chlorides of zinc, lead, copper, cadmium, and nickel, and also contain a small amount of heavy metal oxides. The sulfide sent to the lead-zinc ore metallurgical process for metal purification contains components such as zinc sulfide, lead sulfide, copper sulfide, cadmium sulfide and nickel sulfide. When the mixture after washing is subjected to solid-liquid separation, a filter press method is selected.

[0047] Example 1

[0048] The waste incineration fly ash treatment process in this embodiment specifically includes the following steps:

[0049] (1) The waste incineration fly ash is treated with acid washing. A 1.5 mol / L hydrochloric acid solution is added and stirred at a liquid-to-solid ratio of 3:1 L / kg. The pH of the acid washing solution is monitored. When the pH is within the range of 10, stirring is stopped to end the acid washing. The acid washing mixed solution is then subjected to solid-liquid separation. A filter press is selected for solid-liquid separation. The solid is dried at 105°C for 24 hours to obtain acid washing fly ash and acid washing solution.

[0050] (2) The pickling solution is treated to remove hardness by adding sodium carbonate, and the calcium ion concentration in the pickling solution is finally controlled to be below 100 mg / L. The de-hardening pickling solution is mechanically compressed, evaporated and crystallized to obtain potassium chloride and sodium chloride.

[0051] (3) The pickled fly ash, the sodium chloride obtained in step (2), and the petroleum coke are mixed in a mass percentage of 40%, 30%, and 30%, respectively, and a planetary ball mill is selected for mechanical ball milling at a rotation speed of 400 rpm for 2 hours; the obtained mixed powder is compressed and molded so that the resistance value of the compressed material is 1Ω.

[0052] (4) The compressed material is placed in the Joule heat generating section of the Joule heat flash device for high-temperature Joule heat treatment, with a voltage of 120 V, a time of 3 seconds, a temperature of more than 3000 degrees Celsius, and a discharge number of 8 times; after high-temperature discharge treatment, the heavy metal-rich steam is condensed and collected to obtain heavy metal condensation particles, dioxins are degraded at high temperature, and petroleum coke is converted into graphene, and finally detoxified activated fly ash is obtained.

[0053] (5) The heavy metal condensate particles collected by condensation are dissolved in a 0.1 mol / L hydrochloric acid solution with a liquid-to-solid ratio of 10:1 (L / kg) to obtain a heavy metal chloride solution; sodium sulfide is added to the heavy metal chloride solution to convert all heavy metal ions into sulfide precipitates, which are filtered, collected, dried, and then enter the lead-zinc ore metallurgical process.

[0054] (6) The detoxified activated fly ash is washed with water, and after solid-liquid separation, the solid is dried at 105° C. for 24 hours to obtain desalted detoxified activated fly ash, and the liquid is a washing liquid. The washing liquid is subjected to steam mechanical recompression evaporation crystallization, and the sodium chloride is recovered and reused in step (3) for material matching.

[0055] (7) Desalinated and detoxified activated fly ash, cement clinker, and waste incinerator slag are mixed in a mass percentage ratio of 20%, 40%, and 40%, and water is added according to a water-cement ratio of 0.4 (L / kg) to prepare cement slurry, which is then filled into a cement block mold and compacted by vibration. The mixture is placed in a steam curing box and cured for 1 day before demolding. The mixture is then steam cured for 27 days to obtain a cement slurry block.

[0056] Product performance test:

[0057] The fly ash after Joule heat treatment was subjected to heavy metal leaching test using HJ / T 557-2010 standard, and the leaching results are shown in Table 2. The fly ash after Joule heat treatment was fully digested to determine the heavy metal content and calculate the heavy metal removal rate, and the removal rate results are shown in Table 2.

[0058] The fly ash after Joule heat treatment was tested for dioxin equivalent toxicity. By converting the proportion of fly ash in the material, the overall dioxin equivalent toxicity was 2ng-TEQ / kg, and the dioxin degradation rate was 98.9%.

[0059] The compressive strength of the cement paste specimen tested using a pressure testing machine was 55MPa.

[0060] Table 2 Fly ash leaching concentration and heavy metal recovery rate after treatment in Example 1

[0061]

[0062] ND: Not Detected

[0063] Example 2

[0064] In this embodiment, the waste incineration fly ash is selected the same as that in Embodiment 1.

[0065] The operation process of this embodiment is consistent with that of embodiment 1, and some parameters in each step are adjusted as follows:

[0066] (1) The waste incineration fly ash is treated with acid washing. A 2 mol / L hydrochloric acid solution is added and stirred at a liquid-to-solid ratio of 4:1 L / kg. The pH of the acid washing solution is monitored. When the pH is within the range of 9, stirring is stopped to end the acid washing. The acid washing mixed solution is then subjected to solid-liquid separation. A filter press is selected for solid-liquid separation. The solid is dried at 105°C for 24 hours to obtain acid washing fly ash and acid washing solution.

[0067] (2) The pickling solution is treated to remove hardness by adding sodium carbonate, and the calcium ion concentration of the pickling solution is finally controlled to be below 100 mg / L. The de-hardening pickling solution is mechanically compressed, evaporated and crystallized to obtain potassium chloride and sodium chloride.

[0068] (3) The pickled fly ash, the sodium chloride obtained in step (2), and the petroleum coke are mixed in a mass percentage of 45%, 35%, and 20%, respectively, and a planetary ball mill is selected for mechanical ball milling at a rotation speed of 500 rpm for 1.5 hours; the obtained mixed powder is compressed and molded so that the resistance value of the compressed material is 3Ω.

[0069] (4) The compressed material is placed in the Joule heat generating section of the Joule heat flash device for high-temperature Joule heat treatment, with a voltage of 150 V, a time of 1.5 seconds, a temperature of more than 3000 degrees Celsius, and a discharge number of 5 times; after the high-temperature discharge treatment, the heavy metal-rich steam is condensed and collected to obtain heavy metal condensation particles, dioxins are degraded at high temperature, and petroleum coke is converted into graphene, and finally detoxified activated fly ash is obtained.

[0070] (5) The heavy metal condensate particles collected by condensation are dissolved in a 0.15 mol / L hydrochloric acid solution with a liquid-to-solid ratio of 7.5:1 (L / kg) to obtain a heavy metal chloride solution; sodium sulfide is added to the heavy metal chloride solution to convert all heavy metal ions into sulfide precipitates, which are filtered, collected, dried, and then enter the lead-zinc ore metallurgical process.

[0071] (6) The detoxified activated fly ash is washed with water, and after solid-liquid separation, the solid is dried at 105° C. for 24 hours to obtain desalted detoxified activated fly ash, and the liquid is a washing liquid. The washing liquid is subjected to steam mechanical recompression evaporation crystallization, and the sodium chloride is recovered and reused in step (3) for material matching.

[0072] (7) Desalinated and detoxified activated fly ash, cement clinker, and waste incinerator slag are mixed in mass percentages of 25%, 45%, and 30%, and water is added at a water-cement ratio of 0.35 (L / kg) to prepare cement slurry, which is then put into a cement block mold and vibrated, placed in a steam curing box and cured for 1 day before demolding, and then steam cured for 27 days to obtain a cement slurry block.

[0073] Product performance test:

[0074] The fly ash after Joule heat treatment was subjected to heavy metal leaching test using HJ / T 557-2010 standard, and the leaching results are shown in Table 3. The fly ash after Joule heat treatment was fully digested to determine the heavy metal content and calculate the heavy metal removal rate, and the removal rate results are shown in Table 3.

[0075] The fly ash after Joule heat treatment was tested for dioxin equivalent toxicity. By converting the proportion of fly ash in the material, the overall dioxin equivalent toxicity was 3ng-TEQ / kg, and the dioxin degradation rate was 98.4%.

[0076] The compressive strength of the cement paste specimen tested using a pressure testing machine was 60MPa.

[0077] Table 3 Fly ash leaching concentration and heavy metal recovery rate after treatment in Example 2

[0078]

[0079] ND: Not Detected

[0080] Example 3

[0081] In this embodiment, the waste incineration fly ash is selected the same as that in Embodiment 1.

[0082] The operation process of this embodiment is consistent with that of embodiment 1, and some parameters in each step are adjusted as follows:

[0083] (1) The waste incineration fly ash is treated with acid washing. A 1 mol / L hydrochloric acid solution is added and stirred at a liquid-to-solid ratio of 5:1 L / kg. The pH of the acid washing solution is monitored. When the pH is within the range of 9.5, stirring is stopped and the acid washing is terminated. The acid washing mixed solution is then subjected to solid-liquid separation. A filter press is selected for solid-liquid separation. The solid is dried at 105°C for 24 hours to obtain acid washing fly ash and acid washing solution.

[0084] (2) The pickling solution is treated to remove hardness by adding sodium carbonate, and the calcium ion concentration of the pickling solution is finally controlled to be below 100 mg / L. The de-hardening pickling solution is mechanically compressed, evaporated and crystallized to obtain potassium chloride and sodium chloride.

[0085] (3) The pickled fly ash, the sodium chloride obtained in step (2), and the petroleum coke are mixed in a mass percentage of 50%, 25%, and 25%, respectively, and a planetary ball mill is selected for mechanical ball milling at a rotation speed of 600 rpm for 1 hour; the obtained mixed powder is compressed and molded so that the resistance value of the compressed material is 2Ω.

[0086] (4) The compressed material is placed in the Joule heat generating section of the Joule heat flash device for high-temperature Joule heat treatment, with the voltage set to 180 V, the time to 1 second, the temperature to above 3000 degrees Celsius, and the number of discharges to 10 times; after the high-temperature discharge treatment, the heavy metal-rich steam is condensed and collected to obtain heavy metal condensed particles, dioxins are degraded at high temperature, and the petroleum coke is converted into graphene, and finally detoxified activated fly ash is obtained.

[0087] (5) The heavy metal condensate particles collected by condensation are dissolved in a 0.2 mol / L hydrochloric acid solution with a liquid-to-solid ratio of 5:1 (L / kg) to obtain a heavy metal chloride solution; sodium sulfide is added to the heavy metal chloride solution to convert all heavy metal ions into sulfide precipitates, which are filtered, collected, dried, and then enter the lead-zinc ore metallurgical process.

[0088] (6) The detoxified activated fly ash is washed with water, and after solid-liquid separation, the solid is dried at 105° C. for 24 hours to obtain desalted detoxified activated fly ash, and the liquid is a washing liquid. The washing liquid is subjected to steam mechanical recompression evaporation crystallization, and the sodium chloride is recovered and reused in step (3) for material matching.

[0089] (7) Desalted and detoxified activated fly ash, cement clinker, and waste incinerator slag are mixed in a mass percentage ratio of 30%, 50%, and 20%, and water is added according to a water-cement ratio of 0.3 (L / kg) to prepare cement slurry, which is then filled into a cement block mold and compacted by vibration. The mixture is placed in a steam curing box and cured for 1 day before demolding. The mixture is then steam cured for 27 days to obtain a cement slurry block.

[0090] Product performance test:

[0091] The fly ash after Joule heat treatment was subjected to heavy metal leaching test using HJ / T 557-2010 standard, and the leaching results are shown in Table 4. The fly ash after Joule heat treatment was fully digested to determine the heavy metal content and calculate the heavy metal removal rate, and the removal rate results are shown in Table 4.

[0092] The fly ash after Joule heat treatment was tested for dioxin equivalent toxicity. Based on the proportion of fly ash in the material, the overall dioxin equivalent toxicity was 0.5ng-TEQ / kg, and the dioxin degradation rate was 99.7%.

[0093] The compressive strength of the cement paste specimen tested using a pressure testing machine was 70MPa.

[0094] Table 4 Fly ash leaching concentration and heavy metal recovery rate after treatment in Example 3

[0095]

[0096] ND: Not Detected

[0097] It can be seen from the analysis and test results of each embodiment that the heavy metal extraction efficiency of the process proposed by the present invention is generally greater than 50%, especially Zn and Cd exceed 80%, and the dioxin degradation efficiency exceeds 98%. The heavy metal leaching toxicity and dioxin toxicity equivalent of the samples prepared by the present invention are much lower than the resource utilization requirements specified in the "Technical Specifications for Pollution Control of Fly Ash from Incineration of Municipal Waste" (HJ1134-2020). In addition, using the activated fly ash obtained by the present invention as a cement substitute, the strength of the prepared cement slurry test block can reach more than 50MPa.

[0098] Therefore, the Joule heat-based rapid detoxification and resource utilization method for waste incineration fly ash provided by the present invention has the function of efficiently extracting heavy metals and degrading dioxins, and the fly ash after disposal has high potential for resource utilization. At the same time, the prepared cement slurry test block has excellent mechanical properties. It is a waste incineration fly ash resource utilization technology with great practical engineering application prospects, low cost, low energy consumption, high efficiency, low carbon and environmental protection.

[0099] Obviously, those skilled in the art may make various subsequent applications, supplements, modifications and variations to the present invention without departing from the spirit and scope of the present invention. If various applications, supplements, modifications and variations based on the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such applications, supplements, modifications and variations.

Claims

1. A method for rapid detoxification and resource utilization of waste incineration fly ash based on Joule heat, characterized in that: The following steps are involved: (1) After the waste incineration fly ash is pickled, the pickling mixed solution is separated into solid and liquid, and the solid is dried to obtain pickled fly ash and pickling liquid; (2) Sodium carbonate is added to the pickling solution for hardness removal, and the calcium ion concentration in the pickling solution is finally controlled to be below 100 mg / L; then mechanical compression evaporation crystallization is performed to obtain potassium chloride and sodium chloride; (3) weighing the pickling fly ash, the sodium chloride obtained in step (2), and the petroleum coke in a mass ratio of 40-50:25-35:20-30, adding the mixture into a ball mill for mechanical ball milling; compressing the obtained mixed powder so that the resistance value of the compressed material is between 1 and 3 Ω; (4) placing the compressed material in the Joule heat generating section of the Joule heat flash evaporation device, setting the voltage to 120V~180V, the processing time to 1~3 seconds, the temperature to above 3000°C, and the number of discharges to 5~10 times; after high-temperature discharge treatment, using an ice water bath or liquid nitrogen condensation to collect the heavy metal-rich vapor to obtain heavy metal condensate particles; the main components of the heavy metal condensate particles are chlorides of zinc, lead, copper, cadmium, and nickel, and also contain heavy metal oxides; at the same time, the dioxins contained in the compressed material are degraded under high temperature conditions, and the petroleum coke is converted into graphene, and finally a detoxified activated fly ash is obtained; (5) using hydrochloric acid solution to dissolve heavy metal condensed particles to obtain heavy metal chloride solution; adding sodium sulfide thereto to convert all heavy metal ions into sulfide precipitates; after filtering, collecting and drying, sending the sulfide to the lead-zinc ore metallurgical process for metal purification; (6) washing the detoxified activated fly ash with water, and after solid-liquid separation, drying the solid to obtain desalted detoxified activated fly ash; subjecting the washing liquid to steam mechanical recompression evaporation and crystallization, recovering the obtained sodium chloride and reusing it in step (3) for material matching; (7) Desalinated and detoxified activated fly ash, cement clinker and waste incinerator slag are weighed in a mass ratio of 20-30:40-50:20-40; then, the three materials are mixed with water at a water-cement ratio of 0.3-0.4 L / kg to prepare cement paste, which is used to prepare cement paste blocks.

2. The method according to claim 1, characterized in that In the step (1), 1-2 mol / L hydrochloric acid solution is added at a liquid-to-solid ratio of 3-5:1 L / kg to carry out pickling treatment on the waste incineration fly ash; stirring is continued during the pickling process, and the change in the pH value of the pickling solution is monitored until it stabilizes in the range of 9-10, and then stirring is stopped to end the pickling.

3. The method according to claim 1, characterized in that In the step (1), a filter press method is selected for solid-liquid separation of the pickling mixed solution, and a drying condition is selected at 105° C. and a time of 24 hours.

4. The method according to claim 1, characterized in that: In the step (3), the ball mill is a planetary ball mill, and the speed is set at 400-600 rpm for 1-2 hours during the ball milling process.

5. The method according to claim 1, characterized in that In the step (5), the concentration of the hydrochloric acid solution used to dissolve the heavy metal condensed particles is 0.1-0.2 mol / L, and the added amount is controlled to be a liquid-solid ratio of 5-10:1 L / kg; the sulfides include zinc sulfide, lead sulfide, copper sulfide, cadmium sulfide and nickel sulfide.

6. The method according to claim 1, characterized in that In the step (6), filter pressing is selected for solid-liquid separation, and the drying condition is selected at 105° C. and dried for 24 hours.

7. The method according to claim 1, characterized in that In the step (7), the operation of preparing the cement paste block includes: filling the cement paste into a cement block mold, vibrating it, placing it in a steam curing box for curing for 1 day and then demoulding it; then continuing steam curing for 27 days, and finally obtaining a cement paste block with a compressive strength greater than 50 MPa.

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