Method for innocent treatment of household garbage incineration fly ash

Abstract

The invention discloses a method for innocent treatment of household garbage incineration fly ash, which comprises the following steps: (1) fly ash pretreatment: taking household garbage incineration fly ash as a raw material, and drying to obtain a pretreated fly ash raw material; (2) preparation of a methanesulfonic acid-iron methanesulfonate extracting solution: firstly adding lead oxide into a methanesulfonic acid solution to form lead methanesulfonate, then adding ferric sulfate to mutually convert soluble salts into iron methanesulfonate and precipitate lead sulfate, and taking the light pink supernatant as an extraction stock solution which is a methanesulfonic acid-iron methanesulfonate stock solution; and (3) metal extraction and dechlorination are conducted, specifically, the fly ash raw material and the methanesulfonic acid-iron methanoate solution are mixed to react, and after the reaction is completed, a leaching solution is obtained through filtering. According to the invention, the use of chemical agents is effectively reduced, and the energy consumption is low. And the obtained leachate is subjected to subsequent treatment, so that a methanesulfonic acid-iron methanoate solution can be reused for metal leaching and dechlorination steps, and the whole method is more green and feasible.

Description

Technical Field

[0001] This invention relates to the field of municipal solid waste incineration fly ash treatment technology, specifically to a method for harmlessly treating municipal solid waste incineration fly ash. Background Technology

[0002] Currently, the main methods of domestic waste disposal in China are incineration, landfill, and composting. Among them, incineration technology has become the most effective and mainstream method due to its advantages in achieving harmlessness and volume reduction of domestic waste.

[0003] It is worth noting that secondary pollutants—fly ash—are generated during the incineration of municipal solid waste. Fly ash contains highly toxic elements such as Pb, Cd, Cr, Hg, Sb, and As, as well as trace amounts of persistent organic pollutants. Currently, the main method for treating fly ash both domestically and internationally is to render it harmless before landfilling. However, landfilling not only occupies a large amount of land resources but also poses an environmental risk of heavy metal infiltration. The diverse types of heavy metals in fly ash and the difficulty in its treatment have always been a hot topic of concern in my country and worldwide.

[0004] Currently, another common method for treating fly ash from municipal solid waste incineration is to render it harmless before recycling it. Based on its chemical composition, fly ash has significant resource utilization value. Compared to using fly ash to prepare soil conditioners or adsorbents, its utilization in building materials is more promising in terms of disposal volume, environmental benefits, and economic benefits. This involves using fly ash directly to replace raw materials in traditional building material production, or converting it into raw materials for building material production, including cement, concrete, and expanded clay aggregate. This requires that the fly ash undergo appropriate harmless treatment before entering the building material production line. The main factor affecting the utilization of fly ash as a building material is its high chlorine content. This can cause equipment corrosion during production and make building materials made from fly ash easily corroded during use, significantly affecting their strength. Therefore, pre-treatment of fly ash from waste incineration for dechlorination is a prerequisite for achieving harmless treatment and resource utilization of fly ash.

[0005] Currently, the common methods for dechlorination treatment of fly ash are water washing and acid washing. Acid washing is considered one of the most promising pretreatment technologies for resource recovery because it can effectively remove heavy metals and chloride salts and recover valuable metals. While existing water washing pretreatment can remove some chlorine, a large amount of acid-soluble chlorine (such as...) remains in the fly ash after washing. Furthermore, during subsequent pickling, chloride ions (Cl⁻) form complexes with heavy metal ions (such as Pb²⁺), altering their chemical behavior. This not only affects the leaching efficiency of heavy metals but may also generate more difficult-to-treat chloride-containing byproducts. Pickling also results in large amounts of elements such as Ca, Al, and Si entering the pickling solution, consuming significant amounts of acid and increasing processing costs. It also complicates the composition of subsequent pickling solutions, severely interfering with the separation and recovery of target heavy metals (such as Pb and Zn). The high acidity environment places extremely high demands on the corrosion resistance of equipment such as reactors, pipelines, pumps, and valves, significantly increasing investment and maintenance costs.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a method for harmlessly treating fly ash from municipal solid waste incineration, thereby effectively reducing the chlorine and heavy metal content in the fly ash and overcoming the disadvantages of fly ash from municipal solid waste incineration as a building material raw material, such as low strength and easy corrosion of equipment.

[0008] To achieve the above objectives, the present invention provides a method for harmlessly treating fly ash from municipal solid waste incineration, comprising the following steps:

[0009] (1) Fly ash pretreatment: using fly ash from municipal solid waste incineration as raw material, drying it to obtain pretreated fly ash raw material;

[0010] (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: First, lead oxide is added to the methanesulfonic acid solution to form lead methanesulfonate salt, and then ferric sulfate is added to convert the soluble salts into ferric methanesulfonate, precipitating insoluble lead sulfate. The light pink supernatant is used as the extraction reserve solution, which is the methanesulfonic acid-ferric methanesulfonate reserve solution.

[0011] The reaction process for preparing the methanesulfonic acid-ferric methanesulfonate extract is as follows:

[0012] (1)

[0013] (2)

[0014] (3) Metal extraction and dechlorination: fly ash raw material and methanesulfonic acid-ferric methane solution are mixed and reacted. After the reaction is completed, the leachate is obtained by filtration.

[0015] Preferably, in the above technical solution, step (1) involves grinding the fly ash raw material and drying it at a temperature of 90-120°C until it reaches a constant weight, then cooling it to room temperature and sieving it.

[0016] Preferably, in the above technical solution, the methanesulfonic acid-ferric methanesulfonate stock solution in step (2) contains 0.1-1 mol / L Fe. 3+ The concentration of free methanesulfonic acid is 0.5-2 mol / L, and it contains at least 1 g / L of Pb. 2+ The presence of a small amount of soluble lead ensures that sulfates (from the added ferric sulfate) are completely removed from the stock solution.

[0017] Preferably, in the above technical solution, the methanesulfonic acid-ferric methanesulfonate stock solution in step (2) contains 0.5 mol / L Fe. 3+ The concentration of free methanesulfonic acid is 1.2-1.5 mol / L, and it contains at least 1 g / L of Pb. 2+ The presence of a small amount of soluble lead ensures that sulfates (from the added ferric sulfate) are completely removed from the stock solution.

[0018] Preferably, in the above technical solution, the liquid-solid ratio of the methanesulfonic acid-ferric methaneate solution to fly ash in step (3) is 8-15:1.

[0019] Preferably, in the above technical solution, the liquid-solid ratio (mL / g) of the mixture of methanesulfonic acid-ferric methaneate solution and fly ash in step (3) is 9:1.

[0020] Preferably, in the above technical solution, step (3) of mixing fly ash with methanesulfonic acid-ferric methaneate extract is carried out by stirring at 40-60℃ for 30-120 min. After the mixing reaction is completed, the metal leachate is obtained by filtration.

[0021] Preferably, in the above technical solution, the reaction of fly ash with methanesulfonic acid-ferric methane extract in step (3) is carried out by stirring at 50-60°C for 40-80 minutes. After the reaction is completed, the metal leachate is obtained by filtration.

[0022] Preferably, in the above technical solution, the stirring speed is 450-700 r / min.

[0023] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a method for the harmless treatment of municipal solid waste incineration fly ash by simultaneously performing metal extraction and dechlorination operations on the fly ash using a methanesulfonic acid-ferric methanesulfonate system. Methanesulfonic acid, as a green and environmentally friendly organic acid, has the advantages of strong acidity and low toxicity and corrosiveness. The methanesulfonic acid-ferric methanesulfonate system can effectively leach lead from galena and zinc from sphalerite (ZnS). Applying this extraction system to municipal solid waste incineration fly ash can achieve dechlorination and detoxification effects. Compared with traditional water washing dechlorination and pyrometallurgical metal extraction, this invention effectively reduces the use of chemical agents and has lower energy consumption. The obtained leachate can be further treated to allow the methanesulfonic acid-ferric methanesulfonate solution to be reused in the metal leaching and dechlorination steps, making the entire method more environmentally friendly and feasible. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the method for harmlessly treating fly ash from municipal solid waste incineration according to the present invention. Detailed Implementation

[0025] The following detailed description of specific embodiments is provided in conjunction with the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0026] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" will be understood to include the stated elements or components without excluding other elements or other components. Unless otherwise specified, all raw materials and reagents used in the embodiments are commercially available. Example 1

[0027] The process flow diagram of the method for harmlessly treating fly ash from municipal solid waste incineration using methanesulfonic acid-ferric methanesulfonate solution is as follows: Figure 1 As shown, the process includes three parts: pretreatment of fly ash from municipal solid waste incineration, preparation of methanesulfonic acid-ferric methanesulfonate extract, and metal extraction reaction. Specifically, it includes the following steps:

[0028] (1) Pretreatment of fly ash from municipal solid waste incineration: The fly ash from municipal solid waste incineration obtained from the incineration plant is ground and passed through a 100-mesh sieve, placed in a glass beaker, and dried in an oven at 105°C until constant weight to obtain the original fly ash material.

[0029] The fly ash sample from the municipal solid waste incineration contained 47.7927 wt% CaO, 21.7899 wt% Cl, and 0.9247 wt% ZnO. The content is 0.9749 wt%. The content is 2.7029 wt%, and the CuO content is 0.0782 wt%.

[0030] (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: Lead oxide was added to the methanesulfonic acid solution to form lead methanesulfonate salt, followed by the addition of ferric sulfate, which caused the soluble salts to interconvert into ferric methanesulfonate, precipitating out insoluble lead sulfate. The pink supernatant was used as the extraction stock solution in the extraction experiment. The free methanesulfonic acid concentration in the obtained extract was 1.5 mol / L, and the free Fe concentration was... 3+ The concentration was 0.5 mol / L, and the solution also contained Pb at a concentration of 1 g / L. 2+ .

[0031] (3) Metal extraction and dechlorination reaction: fly ash raw material and methanesulfonic acid-ferric methanesulfonate solution were mixed and reacted under the following conditions: 2 g fly ash sample was taken and 18 ml methanesulfonic acid-ferric methanesulfonate extract was added (liquid-solid ratio of 9:1), the temperature was 50℃, the reaction time was 60 min, the stirring rate was 600 r / min, and the leachate was obtained by filtration after the reaction was completed.

[0032] In this embodiment, the leaching rates of Al, Zn, and Cu can all reach over 97%, with Zn leaching rate at 99.82%, Al leaching rate at 97.35%, and Cu leaching rate at 98.24%. The removal rate of soluble chlorine in fly ash reaches 98.82%, and the treated fly ash meets the kiln entry standards stipulated in the "Technical Specification for Environmental Protection of Solid Waste Co-processing in Cement Kilns". Example 2

[0033] The process flow diagram of the method for harmlessly treating fly ash from municipal solid waste incineration using methanesulfonic acid-ferric methanesulfonate solution is as follows: Figure 1 As shown, the process includes three parts: pretreatment of fly ash from municipal solid waste incineration, preparation of methanesulfonic acid-ferric methanesulfonate extract, and metal extraction reaction. Specifically, it includes the following steps:

[0034] (1) Pretreatment of fly ash from municipal solid waste incineration: The fly ash from municipal solid waste incineration obtained from the incineration plant is ground and passed through a 100-mesh sieve, placed in a glass beaker, and dried in an oven at 105°C until constant weight to obtain the original fly ash material.

[0035] The fly ash sample from the municipal solid waste incineration contained 47.7927 wt% CaO, 21.7899 wt% Cl, and 0.9247 wt% ZnO. The content is 0.9749 wt%. The content is 2.7029 wt%, and the CuO content is 0.0782 wt%.

[0036] (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: Lead oxide was added to the methanesulfonic acid solution to form lead methanesulfonate salt, followed by the addition of ferric sulfate, which caused the soluble salts to interconvert into ferric methanesulfonate, precipitating out insoluble lead sulfate. The pink supernatant was used as the extraction stock solution in the extraction experiment. The free methanesulfonic acid concentration in the obtained extract was 1.0 mol / L, and the free Fe concentration was... 3+ The concentration was 0.5 mol / L, and the solution also contained Pb at a concentration of 1 g / L. 2+ .

[0037] (3) Metal extraction and dechlorination reaction: fly ash raw material and methanesulfonic acid-ferric methanesulfonate solution were mixed and reacted under the following conditions: 2 g fly ash sample was taken and 18 ml methanesulfonic acid-ferric methanesulfonate extract was added (liquid-solid ratio of 9:1), the temperature was 50℃, the reaction time was 60 min, the stirring rate was 600 r / min, and the leachate was obtained by filtration after the reaction was completed.

[0038] In this embodiment, the leaching rates of Al, Zn, and Cu can all reach over 80%, with Zn leaching rate at 82.04%, Al leaching rate at 81.56%, and Cu leaching rate at 84.35%. The removal rate of soluble chlorine in fly ash reaches 97.73%, and the treated fly ash meets the kiln entry standards stipulated in the "Technical Specification for Environmental Protection of Solid Waste Co-processing in Cement Kilns". Example 3

[0039] The process flow diagram of the method for harmlessly treating fly ash from municipal solid waste incineration using methanesulfonic acid-ferric methanesulfonate solution is as follows: Figure 1 As shown, the process includes three parts: pretreatment of fly ash from municipal solid waste incineration, preparation of methanesulfonic acid-ferric methanesulfonate extract, and metal extraction reaction. Specifically, it includes the following steps:

[0040] (1) Pretreatment of fly ash from municipal solid waste incineration: The fly ash from municipal solid waste incineration obtained from the incineration plant is ground and passed through a 100-mesh sieve, placed in a glass beaker, and dried in an oven at 105°C until constant weight to obtain the original fly ash material.

[0041] The fly ash sample from the municipal solid waste incineration contained 47.7927 wt% CaO, 21.7899 wt% Cl, and 0.9247 wt% ZnO. The content is 0.9749 wt%. The content is 2.7029 wt%, and the CuO content is 0.0782 wt%.

[0042] (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: Lead oxide was added to the methanesulfonic acid solution to form lead methanesulfonate salt, followed by the addition of ferric sulfate, which caused the soluble salts to interconvert into ferric methanesulfonate, precipitating out insoluble lead sulfate. The pink supernatant was used as the extraction stock solution in the extraction experiment. The free methanesulfonic acid concentration in the obtained extract was 1.5 mol / L, and the free Fe concentration was... 3+ The concentration was 0.5 mol / L, and the solution also contained Pb at a concentration of 1 g / L. 2+ .

[0043] (3) Metal extraction and dechlorination reaction: fly ash raw material and methanesulfonic acid-ferric methanesulfonate solution were mixed and reacted under the following conditions: 2 g fly ash sample was taken and 18 ml methanesulfonic acid-ferric methanesulfonate extract was added (liquid-solid ratio of 9:1), the temperature was 40℃, the reaction time was 60 min, the stirring rate was 600 r / min, and the leachate was obtained by filtration after the reaction was completed.

[0044] In this embodiment, the leaching rates of Al, Zn, and Cu can all reach over 90%, with Zn leaching rate at 94.11%, Al leaching rate at 91.27%, and Cu leaching rate at 92.34%. The removal rate of soluble chlorine in fly ash reaches 97.93%, and the treated fly ash meets the kiln entry standards stipulated in the "Technical Specification for Environmental Protection of Solid Waste Co-processing in Cement Kilns". Example 4

[0045] The process flow diagram of the method for harmlessly treating fly ash from municipal solid waste incineration using methanesulfonic acid-ferric methanesulfonate solution is as follows: Figure 1 As shown, the process includes three parts: pretreatment of fly ash from municipal solid waste incineration, preparation of methanesulfonic acid-ferric methanesulfonate extract, and metal extraction reaction. Specifically, it includes the following steps:

[0046] (1) Pretreatment of fly ash from municipal solid waste incineration: The fly ash from municipal solid waste incineration obtained from the incineration plant is ground and passed through a 100-mesh sieve, placed in a glass beaker, and dried in an oven at 105°C until constant weight to obtain the original fly ash material.

[0047] The fly ash sample from the municipal solid waste incineration contained 47.7927 wt% CaO, 21.7899 wt% Cl, and 0.9247 wt% ZnO. The content is 0.9749 wt%. The content is 2.7029 wt%, and the CuO content is 0.0782 wt%.

[0048] (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: Lead oxide was added to the methanesulfonic acid solution to form lead methanesulfonate salt, followed by the addition of ferric sulfate, which caused the soluble salts to interconvert into ferric methanesulfonate, precipitating out insoluble lead sulfate. The pink supernatant was used as the extraction stock solution in the extraction experiment. The free methanesulfonic acid concentration in the obtained extract was 1.5 mol / L, and the free Fe concentration was... 3+ The concentration was 0.5 mol / L, and the solution also contained Pb at a concentration of 1 g / L. 2+ .

[0049] (3) Metal extraction and dechlorination reaction: fly ash raw material and methanesulfonic acid-ferric methanesulfonate solution were mixed and reacted under the following conditions: 2 g fly ash sample was taken and 18 ml methanesulfonic acid-ferric methanesulfonate extract was added (liquid-solid ratio of 9:1), the temperature was 50℃, the reaction time was 40 min, the stirring rate was 600 r / min, and the leachate was obtained by filtration after the reaction was completed.

[0050] In this embodiment, the leaching rates of Al, Zn, and Cu can all reach over 87%, with Zn leaching rate at 91.04%, Al leaching rate at 91.95%, and Cu leaching rate at 87.79%. The removal rate of soluble chlorine in fly ash reaches 97.89%, and the treated fly ash meets the kiln entry standards stipulated in the "Technical Specification for Environmental Protection of Solid Waste Co-processing in Cement Kilns". Example 5

[0051] The process flow diagram of the method for harmlessly treating fly ash from municipal solid waste incineration using methanesulfonic acid-ferric methanesulfonate solution is as follows: Figure 1 As shown, the process includes three parts: pretreatment of fly ash from municipal solid waste incineration, preparation of methanesulfonic acid-ferric methanesulfonate extract, and metal extraction reaction. Specifically, it includes the following steps:

[0052] (1) Pretreatment of fly ash from municipal solid waste incineration: The fly ash from municipal solid waste incineration obtained from the incineration plant is ground and passed through a 100-mesh sieve, placed in a glass beaker, and dried in an oven at 105°C until constant weight to obtain the original fly ash material.

[0053] The fly ash sample from the municipal solid waste incineration contained 47.7927 wt% CaO, 21.7899 wt% Cl, and 0.9247 wt% ZnO. The content is 0.9749 wt%. The content is 2.7029 wt%, and the CuO content is 0.0782 wt%.

[0054] (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: Lead oxide was added to the methanesulfonic acid solution to form lead methanesulfonate salt, followed by the addition of ferric sulfate, which caused the soluble salts to interconvert into ferric methanesulfonate, precipitating out insoluble lead sulfate. The pink supernatant was used as the extraction stock solution in the extraction experiment. The free methanesulfonic acid concentration in the obtained extract was 1.5 mol / L, and the free Fe concentration was... 3+ The concentration was 0.5 mol / L, and the solution also contained Pb at a concentration of 1 g / L. 2+ .

[0055] (3) Metal extraction and dechlorination reaction: fly ash raw material and methanesulfonic acid-ferric methanesulfonate solution were mixed and reacted under the following conditions: 2 g fly ash sample was taken and 12 ml methanesulfonic acid-ferric methanesulfonate extract was added (liquid-solid ratio of 6:1), the temperature was 50℃, the reaction time was 60 min, the stirring rate was 600 r / min, and the leachate was obtained by filtration after the reaction was completed.

[0056] In this embodiment, the leaching rates of Al, Zn, and Cu can all reach over 87%, with Zn leaching rate at 90.92%, Al leaching rate at 80.59%, and Cu leaching rate at 83.67%. The removal rate of soluble chlorine from fly ash reaches 94.75%.

[0057] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for harmlessly treating fly ash from municipal solid waste incineration, characterized in that, Includes the following steps: (1) Fly ash pretreatment: using fly ash from municipal solid waste incineration as raw material, drying it to obtain pretreated fly ash raw material; (2) Preparation of methanesulfonic acid-ferric methanesulfonate extract: First, lead oxide is added to the methanesulfonic acid solution to form lead methanesulfonate salt, and then ferric sulfate is added to convert the soluble salts into ferric methanesulfonate, precipitating insoluble lead sulfate. The light pink supernatant is used as the extraction reserve solution, which is the methanesulfonic acid-ferric methanesulfonate reserve solution. (3) Metal extraction and dechlorination: fly ash raw material and methanesulfonic acid-ferric methane solution are mixed and reacted. After the reaction is completed, the leachate is obtained by filtration.

2. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, Step (1) First, grind the fly ash raw material and then dry it at a temperature of 90-120℃ until constant weight. After cooling to room temperature, sieve it.

3. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, Step (2) The methanesulfonic acid-ferric methanesulfonate stock solution contains 0.1-1 mol / L Fe. 3+ The concentration of free methanesulfonic acid is 0.5-2 mol / L, and it contains at least 1 g / L of Pb. 2+ .

4. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, Step (2) The methanesulfonic acid-ferric methanesulfonate stock solution contains 0.5 mol / L Fe 3+ The concentration of free methanesulfonic acid is 1.2-1.5 mol / L, and it contains at least 1 g / L of Pb. 2+ .

5. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, In step (3), the liquid-solid ratio of the methanesulfonic acid-ferric methaneate solution to fly ash is 8-15:1 (mL / g).

6. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, In step (3), the liquid-solid ratio of the methanesulfonic acid-ferric methaneate solution to fly ash is 9:1 (mL / g).

7. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, Step (3) The fly ash and methanesulfonic acid-ferric methane extract are mixed and reacted at 40-60℃ for 30-120 min. After the mixing reaction is completed, the metal leachate is obtained by filtration.

8. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 1, characterized in that, Step (3) The fly ash and methanesulfonic acid-ferric methane extract are mixed and reacted at 50-60℃ for 40-80 min. After the mixing reaction is completed, the metal leachate is obtained by filtration.

9. The method for harmlessly treating fly ash from municipal solid waste incineration according to claim 7 or 8, characterized in that, The stirring speed is 450-700 r / min.

Images