A method for harmless co-disposal of acidic mine wastewater and incineration fly ash

Abstract

The present application belongs to the field of solid waste and wastewater treatment technology, and specifically relates to a method for harmless co-disposal of acid mine wastewater and incineration fly ash, comprising the following steps: adding an alkaline solution to the incineration fly ash to be treated at room temperature to obtain a mixed slurry; heating and stirring the mixed slurry; adding acid mine wastewater to the mixed slurry obtained in the above step until the pH value is adjusted to neutral; transferring the neutral mixed slurry to a microwave hydrothermal reactor for microwave-assisted hydrothermal treatment, and cooling the mixed slurry to room temperature after the treatment; subjecting the cooled mixed slurry to solid-liquid separation, discharging the obtained liquid phase product as waste liquid, and drying the obtained solid phase product for reuse as an adsorbent. The harmless co-disposal method of the present application simultaneously solves the problem of harmless and stabilization treatment of two hazardous wastes, acid mine wastewater and waste incineration fly ash, and the treated fly ash also has extremely strong stability and adsorption properties.

Description

Technical Field

[0001] The present application belongs to the field of solid waste and wastewater treatment technology, and specifically relates to a method for harmlessly co-disposing of acidic mine wastewater and incineration fly ash. Background Art

[0002] Mineral resources are important natural resources that promote the rapid development of human society. However, due to long-term disordered and destructive mining, they have induced a series of ecological and environmental problems. Acid mine drainage (AMD) is a kind of wastewater with low pH and high concentration of sulfate (SO4) produced by oxidation or rainwater erosion of ore during the mining, processing and tailings accumulation process. 2- ) and various toxic heavy metal ions (such as Fe 2+ 、Cu 2+ 、Mn 2+ 、Cd 2+ Industrial wastewater with AMD characteristics (such as sulfide precipitation, neutralization precipitation, electrolysis, ion exchange, and redox methods) can be divided into two main categories. Active treatment technologies include sulfide precipitation, neutralization precipitation, electrolysis, ion exchange, and redox methods. While these technologies offer advantages such as ease of operation, convenient treatment, and short treatment cycles, they can cause secondary pollution during the treatment process and have high operating and maintenance costs. Passive treatment technologies include constructed wetlands, microbial reduction, and BST (Biological Source Treatment) microbial integrated technologies. These technologies offer advantages such as low operating costs, strong applicability, and no secondary pollution. However, due to the inherent tolerance of plants or microorganisms, they have limitations such as a narrow pH range, poor treatment effectiveness for some heavy metal ions, and low treatment efficiency.

[0003] Incineration has become a widely adopted domestic waste treatment technology in my country due to its advantages, including low land occupation, significant waste reduction, and heat recovery. The incineration process produces fly ash, which accounts for 3-5% of the waste mass. Because fly ash contains significant amounts of toxic heavy metals (such as Pb, Cd, and Cr) and volatile organic pollutants like dioxins, it has been listed on the National List of Hazardous Wastes as HW18. Therefore, achieving harmless disposal and resource utilization of fly ash from incineration has become a pressing industry need.

[0004] At present, the harmless treatment technologies for fly ash mainly include cement solidification, chemical stabilization and vitrification / melt solidification. Among them, cement solidification technology uses inorganic / organic solidifying agents to form a solid body with fly ash, and achieves the purpose of heavy metal stabilization by saponification reaction or hydration reaction with heavy metals in fly ash. However, the volume of fly ash treated by this technology is relatively large, and it cannot completely eliminate dioxin-type persistent organic pollutants. At the same time, it is not effective in solidifying amphoteric heavy metals such as lead and zinc. Chemical stabilization technology mainly decomposes toxic substances into low-mobility, low-solubility and low-toxic substances through a series of chemical reactions between organic / inorganic agents and fly ash. However, this technology is difficult to achieve simultaneous stabilization of multiple heavy metals, and the treated waste liquid contains soluble salts and suspended heavy metals, which will cause secondary pollution. Vitrification / melt solidification technology heats fly ash to a melting temperature (700 ~ 2200°C), and then the slag is quickly cooled. During this process, organic pollutants such as fly dioxins will be thermally decomposed and gasified, and the treated fly ash will form a dense and stable glassy slag, which will permanently seal the toxic heavy metals. However, the high melting temperature will cause the heavy metals to volatilize, causing secondary pollution.

[0005] In summary, although there are treatment methods for acid mine drainage and fly ash respectively in the existing technology, they all have the above-mentioned shortcomings. Moreover, the current existing technology does not have a relatively effective method for the harmless co-disposal of acid mine drainage and fly ash at the same time. Summary of the Invention

[0006] In order to solve at least one technical problem existing in the prior art, the present application provides a method for harmless co-disposal of acid mine wastewater and incineration fly ash.

[0007] The present application discloses a method for harmlessly co-disposing acid mine wastewater and incineration fly ash, comprising the following steps:

[0008] Step 1: adding an alkaline solution to the incineration fly ash to be treated at room temperature to obtain a mixed slurry;

[0009] Step 2: heating and stirring the mixed slurry obtained in step 1;

[0010] Step 3: adding acidic mine wastewater to the mixed slurry obtained by stirring in step 2 until the pH value of the mixed slurry is adjusted to neutral;

[0011] Step 4: transferring the neutral mixed slurry obtained in step 3 to a microwave hydrothermal reactor for microwave-assisted hydrothermal treatment;

[0012] Step 5: Cooling the mixed slurry obtained in step 4 to room temperature;

[0013] Step 6: performing solid-liquid separation on the mixed slurry after cooling in step 5, wherein the separated liquid product is discharged as waste liquid, and the separated solid product is dried and reused as an adsorbent.

[0014] According to at least one embodiment of the present application, the heavy metals contained in the acid mine drainage are one or more of Cu, Pb, Zn, Cd, Mn, and Fe.

[0015] According to at least one embodiment of the present application, in step 1, the alkaline solution added is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 0.1-0.3 mol / L, and the liquid-solid ratio is 3-10 mL:1 g.

[0016] According to at least one embodiment of the present application, in step 2, heating and stirring the mixed slurry includes:

[0017] The mixed slurry is transferred to a stirred hydrothermal reactor and stirred at a temperature of 50-90°C and a rotation speed of 200-600 r / min for 1-6 hours; preferably 70-90°C, 300-500 r / min and 2-5 hours; more preferably 90°C, 400 r / min and 3 hours.

[0018] According to at least one embodiment of the present application, in the step 4, the microwave-assisted hydrothermal treatment includes:

[0019] The temperature of the mixed slurry in the microwave hydrothermal reactor is maintained at 100-370°C for 10-120 minutes; more preferably, the temperature is 130-200°C and the microwave hydrothermal reaction time is 10-120 minutes; further preferably, the temperature is 150°C and the microwave hydrothermal reaction time is 20 minutes.

[0020] According to at least one embodiment of the present application, in step six, drying the solid phase product includes:

[0021] The solid phase product was dried at 105±5°C for 12-24h.

[0022] This application has at least the following beneficial technical effects:

[0023] 1) The harmless co-disposal method of acid mine wastewater and incineration fly ash of the present application utilizes the strong alkalinity of sodium hydroxide solution to modify the surface structure of waste incineration fly ash under low temperature conditions, and is conducive to the dissolution of elements such as calcium, silicon and aluminum required for the subsequent microwave hydrothermal synthesis of zeolite minerals; in addition, the alkalinity of the mixed slurry obtained by waste incineration fly ash and sodium hydroxide solution is used to neutralize the acid mine wastewater and adjust the pH to near neutral; further, microwave hydrothermal technology is used to deeply treat the acid mine wastewater and waste incineration fly ash, while simultaneously degrading organic pollutants such as dioxins in the fly ash, effectively converting the heavy metals in the acid mine wastewater and incineration fly ash into a residual state, thereby achieving simultaneous stabilization of the heavy metals; in summary, the disposal method of the present application simultaneously solves the problems of harmless and stabilization treatment of two hazardous wastes, acid mine wastewater and waste incineration fly ash, and the treated fly ash also has extremely strong stability and adsorption properties.

[0024] 2) The harmless co-disposal method of acid mine wastewater and incineration fly ash of the present application is simpler to operate, and only includes two steps: alkaline pretreatment of fly ash and microwave hydrothermal treatment of incineration fly ash and acid mine wastewater; in addition, the present application uses silicon, aluminum and calcium dissolved in fly ash to form zeolite minerals to stabilize heavy metal ions, and does not require the addition of additional heavy metal stabilizers: further, while achieving heavy metal stabilization, the present application can also efficiently degrade persistent organic matter such as dioxins in fly ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of the harmless co-disposal method of acid mine wastewater and incineration fly ash in this application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be understood as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] Example 1:

[0028] In this embodiment, the initial pH value of the acid mine wastewater is 2.43, and the main heavy metal types and concentrations thereof are: Fe: 162.1 mg / L, Cu: 10.21 mg / L, Pb: 5.26 mg / L; the waste incineration fly ash is collected from the fly ash generated by the incineration of domestic waste in a fluidized bed, and the dioxin toxicity equivalent is: 36.20 TEQ μg / g; the fly ash is subjected to a heavy metal leaching toxicity test using the "Solid Waste Leaching Toxicity Leaching Method - Acetate Buffer Solution Method" (HJ / T 300-2007), and the heavy metal concentrations in the leachate are detected to be: Zn: 38.26 mg / L, Pb: 0.37 mg / L, Cu: 12.26 mg / L, Cd: 0.42 mg / L, Cr: 2.10 mg / L, and Ni: 0.28 mg / L.

[0029] like Figure 1 As shown, the method for harmless co-disposal of acid mine wastewater and incineration fly ash in this embodiment includes the following steps:

[0030] Step 1: At room temperature, accurately weigh 20 g of waste incineration fly ash, and evenly mix the fly ash with 0.3 mol / L sodium hydroxide concentrated solution at a liquid-to-solid ratio of 5:1 mL / g to obtain a mixed slurry;

[0031] Step 2: The mixed slurry was transferred to a stirred hydrothermal reactor and reacted at a temperature of 70°C and a stirring speed of 200 r / min for 2 h;

[0032] Step 3: After the reaction in step 2 is completed, adding acidic mine wastewater to the obtained mixed slurry until the pH value of the mixed slurry is adjusted to neutral;

[0033] Step 4: Transfer the mixed slurry in step 3 to a microwave hydrothermal reactor and react at 140° C. for 40 minutes;

[0034] Step 5: Cool the mixed slurry obtained in step 4 naturally to room temperature;

[0035] In step six, the mixed slurry after cooling in step five is subjected to solid-liquid separation to obtain a hydrothermal solid phase product and a hydrothermal liquid phase product, wherein the separated liquid phase product is discharged as waste liquid, and the solid phase product is dried at 100±5°C.

[0036] It should also be noted here that in step 1, the strong alkalinity of the sodium hydroxide solution is used to modify the surface structure of the waste incineration fly ash under low temperature conditions, mainly changing the specific surface area and pore volume of the incineration fly ash, making its specific surface area and pore volume larger, making it easier to adsorb heavy metal ions in the co-treatment process of acidic wastewater.

[0037] Furthermore, the microwave hydrothermal treatment technology involved in step four uses subcritical water as the reaction medium, and utilizes the characteristics of water in the subcritical state (T=100~374°C, P=0.1~22.1 Mpa) such as fast motion acceleration, large ion product constant, and high diffusion coefficient, so that it can be better miscible with organic matter, greatly improving the degradation rate of organic pollution. At the same time, water can change the dielectric properties of waste incineration fly ash, so that it can absorb microwaves well, greatly shortening the dissolution-recrystallization process of elements such as calcium, silicon and aluminum in the fly ash, thereby effectively achieving the stabilization of toxic heavy metals; in addition, microwave hydrothermal treatment technology also has the advantages of simple operation, high treatment efficiency, and low secondary pollution.

[0038] Furthermore, the reason for using a microwave hydrothermal reactor rather than supercritical hydrothermal treatment in step 4 of this application is that supercritical hydrothermal treatment is used to treat fly ash and wastewater mixtures. Wastewater typically contains a large number of difficult-to-degrade organic pollutants. This technology primarily utilizes the changes in density, viscosity, and dielectric constant of water molecules in a supercritical state to alter the polarity of water, making it a good solvent for organic matter and thereby degrading the organic pollutants. However, the wastewater involved in this application contains a large number of metal ions. As the reaction temperature rises to near-critical temperatures (~350-400°C), the reaction medium transforms from water into a supercritical metal fluid. This causes silicon, aluminum, and calcium dissolved from the fly ash to rapidly precipitate and crystallize during the supercritical gas-liquid separation process, hindering the nucleation of zeolite-like minerals and thus reducing the stabilization efficiency of heavy metals. The advantage of microwave hydrothermal technology over supercritical hydrothermal technology lies primarily in energy consumption. Microwave hydrothermal reaction temperatures typically range from 100-200°C, and the reactor operating power is generally 1 kW. In contrast, supercritical hydrothermal reaction temperatures are ≥ 374°C, and the reactor operating power is ≥ 3 kW. Therefore, the use of microwave hydrothermal can significantly reduce energy consumption and operating costs.

[0039] Finally, the dioxin content in the hydrothermal solid phase product was analyzed by high-resolution gas chromatography / high-resolution mass spectrometry HRGC / MS. The analytical results showed that the dioxin toxicity equivalent of the hydrothermal solid phase product was 1.52ng-TEQ / g, which was 95.80% lower than that of the original fly ash. The heavy metal leaching toxicity experiment was carried out on the dried solid phase product according to the "Solid Waste Leaching Toxicity Leaching Method Acetate Buffer Solution Method" (HJ / T 300-2007). The heavy metal leaching concentrations in the solid phase product were as follows: Zn: 2.27 mg / L, Pb: 0.18 mg / L, Cu: 1.16 mg / L, Cd: 0.022 mg / L, Cr: 0.086 mg / L, Ni: 0.024 mg / L; further, inductively coupled plasma mass spectrometry ICP-MS was used to analyze the concentrations of heavy metals in the leachate and waste liquid, and the pH of the hydrothermal liquid phase product was 7.81, and the heavy metal concentrations were: Zn: 1.42 mg / L, Pb: 0.86 mg / L, Cu: 0.32 mg / L, Cd: 0.042 mg / L, Cr: 0.057 mg / L, Ni: 0.036 mg / L; Fe: 4.12 mg / L.

[0040] In summary, the leaching concentration of heavy metals in the hydrothermal solid phase product after treatment is far lower than the limit required by the "Pollution Control Standard for Municipal Waste Landfill" (GB16889-2008); the concentration of heavy metals in the hydrothermal liquid phase fully meets the "Integrated Wastewater Discharge Standard" (GB8978-1996).

[0041] In addition, through the cation exchange capacity and heavy metal adsorption experiments on the hydrothermal solid phase product, it can be seen that the cation exchange capacity of the incineration fly ash after treatment by the process of this embodiment is 0.812meq / g, which has good adsorption performance and has a full application prospect as an adsorbent resource utilization.

[0042] Example 2:

[0043] In this embodiment, the initial pH value of the acid mine wastewater is 3.21, and the main heavy metal types and concentrations contained in it are: Fe: 126.1 mg / L, Mn: 6.21 mg / L, Pb: 3.41 mg / L; the waste incineration fly ash is collected from the fly ash generated by the incineration of domestic waste in a fluidized bed, and the dioxin toxicity equivalent is: 40.81 TEQ μg / g; through the heavy metal leaching toxicity test on the fly ash, the heavy metal concentrations in the leachate are detected to be: Zn: 16.32 mg / L, Pb: 0.35 mg / L, Cu: 6.21 mg / L, Cd: 0.16 mg / L, Cr: 0.85 mg / L, Ni: 0.46 mg / L.

[0044] Similarly, the method for harmlessly co-disposing acid mine wastewater and incineration fly ash of this embodiment includes the following steps:

[0045] Step 1: At room temperature, accurately weigh 20 g of waste incineration fly ash, and evenly mix the fly ash with 0.2 mol / L sodium hydroxide concentrate at a liquid-to-solid ratio of 7:1 ml / g to obtain a mixed slurry;

[0046] Step 2: The mixed slurry was transferred to a stirred hydrothermal reactor and reacted at a temperature of 70°C and a stirring speed of 300 r / min for 4 hours;

[0047] Step 3: After the reaction in step 2 is completed, adding acidic mine wastewater to the obtained mixed slurry until the pH value of the mixed slurry is adjusted to neutral;

[0048] Step 4: Transfer the mixed slurry in step 3 to a microwave hydrothermal reactor and react at 200° C. for 30 minutes;

[0049] Step 5: Cool the mixed slurry obtained in step 4 naturally to room temperature;

[0050] In step six, the mixed slurry after cooling in step five is subjected to solid-liquid separation to obtain a hydrothermal solid phase product and a hydrothermal liquid phase product, wherein the separated liquid phase product is discharged as waste liquid, and the solid phase product is dried at 100±5°C.

[0051] Finally, the dioxin content in the hydrothermal solid phase product was analyzed by high-resolution gas chromatography / high-resolution mass spectrometry HRGC / MS. The analytical results showed that the dioxin toxicity equivalent of the hydrothermal solid phase product was 1.66ng-TEQ / g, which was 95.93% lower than that of the original fly ash. The heavy metal leaching toxicity experiment was carried out on the dried solid phase product according to the "Solid Waste Leaching Toxicity Leaching Method Acetate Buffer Solution Method" (HJ / T 300-2007). The heavy metal leaching concentrations in the solid phase product were as follows: Zn: 3.26 mg / L, Pb: 0.13 mg / L, Cu: 0.96 mg / L, Cd: 0.046 mg / L, Cr: 0.053 mg / L, Ni: 0.082 mg / L; further, inductively coupled plasma mass spectrometry ICP-MS was used to analyze the concentrations of heavy metals in the leachate and waste liquid, and the pH of the hydrothermal liquid phase product was 8.16, and the heavy metal concentrations were: Zn: 1.62 mg / L, Pb: 0.79 mg / L, Cu: 0.44 mg / L, Cd: 0.032 mg / L, Cr: 0.061 mg / L, Ni: 0.091 mg / L, Fe: 5.63 mg / L, and Mn: 0.62 mg / L.

[0052] Similarly, in this embodiment, the leaching concentration of heavy metals in the hydrothermal solid phase product after treatment is much lower than the limit required by the "Pollution Control Standard for Municipal Waste Landfill" (GB16889-2008); the concentration of heavy metals in the hydrothermal liquid phase fully meets the "Integrated Sewage Discharge Standard" (GB8978-1996); in addition, through the cation exchange capacity and heavy metal adsorption experiments on the hydrothermal solid phase product, it can be seen that the cation exchange capacity of the incineration fly ash after treatment by the process of this embodiment is 0.796meq / g, which has good adsorption performance and has complete application prospects as an adsorbent resource utilization.

[0053] Example 3:

[0054] In this embodiment, the initial pH value of the acid mine wastewater is 2.96, and the main heavy metal types and concentrations contained in it are: Fe: 141.8 mg / L, Mn: 7.32 mg / L, Pb: 3.41 mg / L, Cd: 1.32 mg / L; the waste incineration fly ash is collected from the fly ash generated by the incineration of domestic waste in a fluidized bed, and the dioxin toxicity equivalent is: 39.12 TEQ μg / g; through the heavy metal leaching toxicity test on the fly ash, the heavy metal concentrations in the leachate are detected to be: Zn: 40.51 mg / L, Pb: 0.66 mg / L, Cu: 18.61 mg / L, Cd: 0.28 mg / L, Cr: 0.54 mg / L, Ni: 0.39 mg / L.

[0055] Similarly, the method for harmlessly co-disposing acid mine wastewater and incineration fly ash of this embodiment includes the following steps:

[0056] Step 1: At room temperature, accurately weigh 20 g of waste incineration fly ash, and evenly mix the fly ash with 0.1 mol / L sodium hydroxide concentrate at a liquid-to-solid ratio of 10:1 ml / g to obtain a mixed slurry;

[0057] Step 2: The mixed slurry was transferred to a stirred hydrothermal reactor and reacted at a temperature of 90°C and a stirring speed of 400 r / min for 6 hours;

[0058] Step 3: After the reaction in step 2 is completed, adding acidic mine wastewater to the obtained mixed slurry until the pH value of the mixed slurry is adjusted to neutral;

[0059] Step 4: Transfer the mixed slurry in step 3 to a microwave hydrothermal reactor and react at 150° C. for 20 min;

[0060] Step 5: Cool the mixed slurry obtained in step 4 naturally to room temperature;

[0061] In step six, the mixed slurry after cooling in step five is subjected to solid-liquid separation to obtain a hydrothermal solid phase product and a hydrothermal liquid phase product, wherein the separated liquid phase product is discharged as waste liquid, and the solid phase product is dried at 100±5°C.

[0062] Finally, the dioxin content in the hydrothermal solid phase product was analyzed by high-resolution gas chromatography / high-resolution mass spectrometry HRGC / MS. The analytical results showed that the dioxin toxicity equivalent of the hydrothermal solid phase product was 1.89 ng-TEQ / g, which was 95.17% lower than that of the original fly ash. The heavy metal leaching toxicity experiment was carried out on the dried solid phase product according to the "Solid Waste Leaching Toxicity Leaching Method Acetate Buffer Solution Method" (HJ / T 300-2007). The heavy metal leaching concentrations in the solid phase product were as follows: Zn: 6.26 mg / L, Pb: 0.21 mg / L, Cu: 2.45 mg / L, Cd: 0.051 mg / L, Cr: 0.060 mg / L, Ni: 0.074 mg / L; further, inductively coupled plasma mass spectrometry ICP-MS was used to analyze the concentrations of heavy metals in the leachate and waste liquid, and the pH of the hydrothermal liquid phase product was 8.23, and the heavy metal concentrations were: Zn: 1.49 mg / L, Pb: 0.85 mg / L, Cu: 0.38 mg / L, Cd: 0.065 mg / L, Cr: 0.072 mg / L, Ni: 0.088 mg / L, Fe: 6.98 mg / L, and Mn: 0.71 mg / L.

[0063] Similarly, in this embodiment, the leaching concentration of heavy metals in the hydrothermal solid phase product after treatment is much lower than the limit required by the "Pollution Control Standard for Municipal Waste Landfill" (GB16889-2008); the concentration of heavy metals in the hydrothermal liquid phase fully meets the "Integrated Sewage Discharge Standard" (GB8978-1996); in addition, through the cation exchange capacity and heavy metal adsorption experiments on the hydrothermal solid phase product, it can be seen that the cation exchange capacity of the incineration fly ash after treatment by the process of this embodiment is 0.788meq / g, which has good adsorption performance and has complete application prospects as an adsorbent resource utilization.

[0064] Example 4:

[0065] In this embodiment, the initial pH value of the acid mine drainage is 2.89, and the main heavy metal types and concentrations contained in it are: Fe: 132.6 mg / L, Cu: 9.84 mg / L, Pb: 2.98 mg / L; the waste incineration fly ash is collected from the fly ash generated by the incineration of domestic waste in a fluidized bed, and the dioxin toxicity equivalent is: 39.26 TEQμg / g; through the heavy metal leaching toxicity test on the fly ash, the heavy metal concentrations in the leachate are detected to be: Zn: 67.32 mg / L, Pb: 0.55 mg / L, Cu: 26.51 mg / L, Cd: 0.19 mg / L, Cr: 0.75 mg / L, and Ni: 0.66 mg / L.

[0066] Similarly, the method for harmlessly co-disposing acid mine wastewater and incineration fly ash of this embodiment includes the following steps:

[0067] Step 1: At room temperature, accurately weigh 20 g of waste incineration fly ash, and evenly mix the fly ash with 0.25 mol / L sodium hydroxide concentrate at a liquid-to-solid ratio of 6:1 mL / g to obtain a mixed slurry;

[0068] Step 2: The mixed slurry was transferred to a stirred hydrothermal reactor and reacted at a temperature of 60°C and a stirring speed of 300 r / min for 3 h;

[0069] Step 3: After the reaction in step 2 is completed, adding acidic mine wastewater to the obtained mixed slurry until the pH value of the mixed slurry is adjusted to neutral;

[0070] Step 4: Transfer the mixed slurry in step 3 to a microwave hydrothermal reactor and react at 350° C. for 30 min;

[0071] Step 5: Cool the mixed slurry obtained in step 4 naturally to room temperature;

[0072] In step six, the mixed slurry after cooling in step five is subjected to solid-liquid separation to obtain a hydrothermal solid phase product and a hydrothermal liquid phase product, wherein the separated liquid phase product is discharged as waste liquid, and the solid phase product is dried at 100±5°C.

[0073] Finally, the dioxin content in the hydrothermal solid phase product was analyzed by high-resolution gas chromatography / high-resolution mass spectrometry HRGC / MS. The analytical results showed that the dioxin toxicity equivalent of the hydrothermal solid phase product was 0.96 ng-TEQ / g, which was 97.55% lower than that of the original fly ash. The heavy metal leaching toxicity experiment was carried out on the dried solid phase product according to the "Solid Waste Leaching Toxicity Leaching Method Acetate Buffer Solution Method" (HJ / T 300-2007). The heavy metal leaching concentrations in the solid phase product were as follows: Zn: 9.07 mg / L, Pb: 0.091 mg / L, Cu: 5.69 mg / L, Cd: 0.016 mg / L, Cr: 0.035 mg / L, Ni: 0.078 mg / L; further, inductively coupled plasma mass spectrometry ICP-MS was used to analyze the concentrations of heavy metals in the leachate and waste liquid, and the pH value of the hydrothermal liquid phase product was 8.09, and the heavy metal concentrations were: Zn: 1.33 mg / L, Pb: 0.65 mg / L, Cu: 0.39 mg / L, Cd: 0.018 mg / L, Cr: 0.054 mg / L, Ni: 0.078 mg / L, Fe: 5.28 mg / L, and Mn: 0.58 mg / L.

[0074] Similarly, in this embodiment, the leaching concentration of heavy metals in the hydrothermal solid phase product after treatment is far lower than the limit required by the "Pollution Control Standard for Municipal Waste Landfill" (GB16889-2008); the concentration of heavy metals in the hydrothermal liquid phase fully meets the "Integrated Sewage Discharge Standard" (GB8978-1996); in addition, through the cation exchange capacity and heavy metal adsorption experiments on the hydrothermal solid phase product, it can be seen that the cation exchange capacity of the incineration fly ash after treatment by the process of this embodiment is 0.857 meq / g, which has good adsorption performance and has full application prospects for resource utilization as an adsorbent.

[0075] However, it should be noted that the temperature in the microwave hydrothermal reactor in Example 4 is 350° C. Although the harmless treatment of incineration fly ash and mine acidity can be achieved simultaneously, compared with Examples 1-3, the excessively high reaction temperature in Example 4 will correspondingly increase energy consumption.

[0076] It can be seen from the above four embodiments that the method for harmless co-disposal of acidic mine wastewater and incineration fly ash of the present application can effectively achieve the simultaneous removal of toxic substances in mineral acidic wastewater and waste incineration fly ash, and has the advantages of simple operation, high disposal efficiency, and low disposal cost. In addition, the treated hydrothermal solid phase product can also be used as an adsorbent for resource recycling, making the value created by this application more adapted to my country's national conditions, and providing a theoretical basis and technical support for the industrial development of harmless disposal and resource utilization of acidic mine wastewater and waste incineration fly ash.

[0077] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for harmless co-disposal of acid mine wastewater and incineration fly ash, characterized in that: The steps include: Step 1: adding an alkaline solution to the incineration fly ash to be treated at room temperature to obtain a mixed slurry; Step 2: heating and stirring the mixed slurry obtained in step 1; Step 3: adding acidic mine wastewater to the mixed slurry obtained by stirring in step 2 until the pH value of the mixed slurry is adjusted to neutral; Step 4: transferring the neutral mixed slurry obtained in step 3 to a microwave hydrothermal reactor for microwave-assisted hydrothermal treatment; Step 5: Cooling the mixed slurry obtained in step 4 to room temperature; Step 6: performing solid-liquid separation on the mixed slurry after cooling in step 5, wherein the separated liquid product is discharged as waste liquid, and the separated solid product is dried and reused as an adsorbent.

2. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 1, characterized in that: The heavy metals contained in the acid mine wastewater are one or more of Cu, Pb, Zn, Cd, Mn and Fe.

3. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 2, characterized in that: In the step 1, the alkaline solution added is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 0.1-0.3 mol / L, and the liquid-solid ratio is 3-10 mL:1 g.

4. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 3, characterized in that: In the step 2, heating and stirring the mixed slurry comprises: The mixed slurry is transported to a stirred hydrothermal reactor and stirred at a temperature of 50-90° C. and a rotation speed of 200-600 r / min for 1-6 hours.

5. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 4, characterized in that: The mixed slurry is subjected to a heating and stirring process comprising: The mixed slurry is transported to a stirred hydrothermal reactor and stirred at a temperature of 70-90° C. and a rotation speed of 300-500 r / min for 2-5 hours.

6. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 5, wherein the heating and stirring treatment of the mixed slurry comprises: The mixed slurry was transferred to a stirred hydrothermal reactor and stirred at a temperature of 90° C. and a rotation speed of 400 r / min for 3 h.

7. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 4, characterized in that: In the step 4, the microwave-assisted hydrothermal treatment includes: The temperature of the mixed slurry in the microwave hydrothermal reaction kettle is maintained at 100-370° C. for 10-120 minutes.

8. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 7, characterized in that: The microwave-assisted hydrothermal treatment comprises: The temperature of the mixed slurry in the microwave hydrothermal reaction kettle is maintained at 130-200° C. for 15-60 minutes.

9. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 7, characterized in that: In the step 4, the microwave-assisted hydrothermal treatment includes: The temperature of the mixed slurry in the microwave hydrothermal reactor was maintained at 150° C. for 20 minutes.

10. The method for harmless co-disposal of acid mine wastewater and incineration fly ash according to claim 7, characterized in that: In the step 6, drying the solid phase product comprises: The solid phase product was dried at 105±5°C for 12-24h.

Images