Harmless deep utilization method for household garbage incineration fly ash

Abstract

The invention discloses a harmless deep utilization method for household garbage incineration fly ash. The harmless deep utilization method comprises the steps that firstly, fly ash and water are mixed and pulped, and then the fly ash and water are fed into a ball mill to be subjected to ball milling; step 2, putting the slurry into a stirring kettle, then adding washing liquor into the stirring kettle, starting to stir, adding a heavy metal chelating agent and a flocculating agent, and then carrying out primary solid-liquid separation; 3, sodium carbonate is added into clear liquid obtained in the primary solid-liquid separation, the PH value is controlled to range from 10 to 12, and then secondary solid-liquid separation is conducted; step 4, uniformly mixing solid substances obtained in the primary solid-liquid separation and the secondary solid-liquid separation with a curing agent and reducing powder, preparing sintered balls by using a calcium-based adhesive, feeding the sintered balls into a sintering kiln for melting and sintering, and cooling to obtain sintered blocks; and step five, crushing and grinding the sintered block to obtain the cement-reinforced admixture finished product. According to the mode, the combined cement reinforcing material can be obtained, so that the pollution of heavy metals to the environment is reduced while the deep treatment of the garbage is realized.

Description

Technical Field

[0001] The invention relates to the field of resource recovery and reuse, and in particular to a method for harmless deep utilization of fly ash from incineration of domestic waste. Background Art

[0002] Although waste incineration power generation can realize resource processing of most of the waste, the final products fly ash and slag produced in the process still have strong pollution to the environment. The reason is that on the one hand, the strong carcinogenic dioxins produced in the flue gas generated by waste incineration during the process of flue gas temperature drop will be fly ash when the flue gas temperature drops. Secondly, the sources of waste are complex. Fly ash and slag are generally enriched with various heavy metal salts and chlorine elements. If these substances are disposed of at will, they will often cause serious pollution to the surrounding environment. In order to eliminate the above problems, our company has developed a harmless treatment method "CN112845498A". After the above treatment, the solidified sintered body enriched with heavy metals is obtained. However, when this solidified sintered body enriched with heavy metals is turned into powder by grinding and other methods and added to cement and other building materials, it is found that it has a great impact on the performance of the building materials themselves. Therefore, it cannot be promoted and can only be piled up and landfilled. Summary of the invention

[0003] The main technical problem solved by the present invention is to provide a fly ash harmless treatment method, which can deeply utilize fly ash and slag, realize maximum utilization of resources, and reduce landfill occupancy.

[0004] In order to solve the above technical problems, a technical solution adopted by the present invention is to provide a method for harmless and deep utilization of fly ash from incineration of domestic waste, and the method for harmless and comprehensive utilization of fly ash from domestic waste comprises:

[0005] Step 1: Mix fly ash and water to make slurry and then send them into a ball mill to grind until the particle size of the slurry is no more than 10 μm;

[0006] Step 2: Put the slurry obtained in step 1 into a stirring tank, then add the washing liquid into the stirring tank and start stirring. During the stirring process, add the heavy metal chelating agent and the flocculant in turn, stir for 0.5 to 1 hour, and use a centrifuge to perform solid-liquid separation after the reaction is complete;

[0007] Step 3: adding soda ash to the clear liquid obtained in the first solid-liquid separation, controlling the pH value to be between 10 and 12, and then using a centrifuge to perform a second solid-liquid separation. The clear liquid obtained from the second solid-liquid separation is desalted and reused as pulping water in step 1 and washing liquid in step 2;

[0008] Step 4: Evenly mix the solid matter obtained from the primary solid-liquid separation and the secondary solid-liquid separation with the curing agent and the reducing powder, and then use a calcium-based adhesive to make sintered balls, which are sent to a sintering kiln for melting and sintering, and then cooled to obtain sintered blocks;

[0009] Step 5: crushing and grinding the sintered block to obtain cement reinforced admixture.

[0010] In a preferred embodiment of the present invention, the fly ash is further mixed with slag material not exceeding 10% of the total fly ash.

[0011] In a preferred embodiment of the present invention, the ratio of fly ash to water during slurrying in step one is 2-3:1, and the amount of water added in step two is 3-5 times the amount of fly ash in step one.

[0012] In a preferred embodiment of the present invention, the amount of the heavy metal chelating agent added in step 2 is 0.5-1.5% of the amount of fly ash.

[0013] In a preferred embodiment of the present invention, the flocculant used in the step 2 is an anionic organic flocculant, and the amount of the flocculant added is 0.01-0.5% of the amount of fly ash added.

[0014] In a preferred embodiment of the present invention, the mixing ratio of the solid substance to the curing agent and the reducing powder in step 4 is 6-10:2-4:1.

[0015] In a preferred embodiment of the present invention, the components of the curing agent in step 4 are proportioned by mass as follows: 5-10 parts of kaolin, 30-40 parts of quartz powder / glass powder, 5-10 parts of borax, and 3-5 parts of calcium oxide.

[0016] In a preferred embodiment of the present invention, the reducing powder is a mixture of activated carbon powder and anthracite powder in any proportion.

[0017] In a preferred embodiment of the present invention, the clear liquid obtained by the secondary solid-liquid separation in step three is separated and desalted by a reverse osmosis device, and the concentrated brine obtained in the separation process is evaporated and crystallized to recover inorganic salts, and the clear liquid is reused.

[0018] In a preferred embodiment of the present invention, the end point of the grinding in step 5 is an average particle size not greater than 500 meshes.

[0019] The beneficial effect of the present invention is that the present invention is a further optimization of the original treatment method of the company. By modifying the existing process, the fly ash is treated before sintering, the chloride ions in the fly ash are removed while enriching and capturing heavy metal elements, and then the part enriched with heavy metal elements is sintered and solidified and then ground into powder for use as a reinforcing agent for cement materials. There is no need for landfill and other treatment methods, so the deep treatment of domestic waste is achieved, which is more environmentally friendly. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0021] The contents of the embodiments of the present invention include:

[0022] Example 1

[0023] A method for harmless and comprehensive utilization of fly ash from incineration of domestic waste, comprising:

[0024] Step 1: Mix fly ash and water in a ratio of 2:1 to prepare a slurry, and then feed the mixture into a ball mill and grind the mixture until the particle size of the slurry is no more than 10 μm, wherein the fly ash is mixed with about 10% of slag material;

[0025] Step 2: Put the slurry obtained in step 1 into a stirring kettle, then add washing liquid 3 times the mass of fly ash into the stirring kettle and start stirring, and add heavy metal chelating agent and flocculant into the stirring kettle in sequence during the stirring process, stir for 0.5 to 1 hour, and use a centrifuge to perform solid-liquid separation after the reaction is complete, wherein the heavy metal chelating agent is sodium hexametaphosphate, and the addition amount is 1% of the fly ash addition amount, and the flocculant is sodium polyacrylate, and the addition amount is 0.2% of the fly ash addition amount;

[0026] Step 3: adding soda ash to the clear liquid obtained in the first solid-liquid separation, controlling the pH value to be between 10 and 12, and then using a centrifuge to perform a second solid-liquid separation, and separating and desalting the clear liquid obtained by the second solid-liquid separation through a reverse osmosis device; the concentrated brine obtained in the separation process of the reverse osmosis device is evaporated and crystallized to obtain inorganic salts, and the clear liquid is used as pulping water in step 1 and washing liquid in step 2;

[0027] Step 4: Evenly mix the solid matter obtained from the primary solid-liquid separation and the secondary solid-liquid separation with the curing agent and the reducing powder, and then use a calcium-based adhesive to make sintered balls, which are sent to a sintering kiln for melting and sintering, and then cooled to obtain sintered blocks;

[0028] Step 5: crushing and grinding the sintered block to an average particle size of no more than 500 meshes to obtain a finished cement reinforced admixture.

[0029] The mixing ratio of the solid matter in step 4 to the curing agent and the reducing powder is 10:4:1. The components of the curing agent are proportioned by mass as follows: 5 parts of kaolin, 40 parts of glass powder, 50 parts of borax, and 5 parts of calcium oxide. The role of kaolin, quartz powder and borax in the curing agent is to help the sintered ball to become a glassy substance after high-temperature melting, solidify the heavy metal components therein, and the role of calcium oxide is to absorb chloride ions in the process when dioxins are decomposed, preventing secondary reactions from occurring. The reducing powder is a mixture of activated carbon powder and anthracite powder in any proportion. By mixing the reducing powder, the entire sintered ball can be quickly burned through to reduce the generation of harmful smoke.

[0030] Example 2

[0031] A method for harmless and comprehensive utilization of fly ash from incineration of domestic waste, comprising:

[0032] Step 1: Mix fly ash and water in a ratio of 3:1 to prepare a slurry, and then feed the mixture into a ball mill and grind the mixture until the particle size of the slurry is no more than 10 μm, wherein the fly ash is mixed with about 20% of slag material;

[0033] Step 2: Put the slurry obtained in step 1 into a stirring kettle, then add a washing liquid 5 times the mass of fly ash into the stirring kettle, start the stirrer to stir, and add a heavy metal chelating agent and a flocculant into the stirring kettle in sequence during the stirring process, and then stir for 0.5 to 1 hour. After the reaction is complete, use a centrifuge to perform a solid-liquid separation, wherein the heavy metal chelating agent is sodium hexametaphosphate, and the addition amount is 1% of the fly ash addition amount, and the flocculant is sodium polyacrylate, and the addition amount is 0.3% of the fly ash addition amount;

[0034] Step 3: adding soda ash to the clear liquid obtained in the first solid-liquid separation, controlling the pH value to be between 10 and 12, and then using a centrifuge to perform a second solid-liquid separation, and separating and desalting the clear liquid obtained by the second solid-liquid separation through a reverse osmosis device; the concentrated brine obtained in the separation process of the reverse osmosis device is evaporated and crystallized to obtain recovered inorganic salts, and the clear liquid is used as pulping water in step 1 and washing liquid in step 2;

[0035] Step 4: Evenly mix the solid matter obtained from the primary solid-liquid separation and the secondary solid-liquid separation with the curing agent and the reducing powder, and then use a calcium-based adhesive to make sintered balls, which are sent to a sintering kiln for melting and sintering, and then cooled to obtain sintered blocks;

[0036] Step 5: crushing and grinding the sintered block to an average particle size of no more than 500 meshes to obtain a finished cement reinforced admixture.

[0037] The mixing ratio of the solid matter in step 4 to the curing agent and the reducing powder is 6:2:1. The components of the curing agent are proportioned by mass as follows: 10 parts of kaolin, 30 parts of quartz powder, 10 parts of borax, and 3 parts of calcium oxide. The role of kaolin, quartz powder and borax in the curing agent is to help the sintered ball to become a glassy substance after high-temperature melting, solidify the heavy metal components therein, and the role of calcium oxide is to absorb chloride ions in the process when dioxin decomposes, preventing secondary reactions from occurring. The reducing powder is a mixture of activated carbon powder and anthracite powder in any proportion. By mixing the reducing powder, the entire sintered ball can be quickly burned through to reduce the generation of harmful smoke.

[0038] The above-mentioned embodiments 1 and 2 are two implementation process routes adjusted based on the different filling amounts of slag materials. In the process route of the present invention, compared with the initial harmless treatment route of the company, the main difference is that in step 1 and step 2, the chloride salt in the fly ash and slag is washed out, and the harmful substances are preliminarily dissociated by ball milling, and the solid matter obtained by the centrifuge is mixed with the curing agent and the reducing agent, and the difficulty of sintering is reduced. When heated at 1200°C for 4 to 6 hours, the degree of vitrification can reach more than 40%, and the heavy metal elements are solidified in the glass phase, which can significantly reduce the leaching rate of heavy metals and have little effect on the environment. The sintered material obtained by the above method is ground to 500 mesh and then added to cement at a ratio of 5% to 10%. It is used as a reinforcing agent. In practical applications, it not only has high molding strength, but also does not crack on the surface, and has no effect on the service life of cement. This not only reduces the cost of raw materials for construction but also realizes the deep comprehensive utilization of waste.

[0039] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for harmless deep utilization of fly ash from incineration of domestic waste, characterized in that: The method for harmless comprehensive utilization of domestic waste fly ash comprises: Step 1: Mix fly ash and water to make slurry and then send them into a ball mill to grind until the particle size of the slurry is no more than 10 μm; Step 2: Put the slurry obtained in step 1 into a stirring tank, then add the washing liquid into the stirring tank and start stirring. During the stirring process, add the heavy metal chelating agent and the flocculant in turn, stir for 0.5 to 1 hour, and use a centrifuge to perform solid-liquid separation after the reaction is complete; Step 3: adding soda ash to the clear liquid obtained in the first solid-liquid separation, controlling the pH value to be between 10 and 12, and then using a centrifuge to perform a second solid-liquid separation. The clear liquid obtained from the second solid-liquid separation is desalted and reused as pulping water in step 1 and washing liquid in step 2; Step 4: Evenly mix the solid matter obtained from the primary solid-liquid separation and the secondary solid-liquid separation with the curing agent and the reducing powder, and then use a calcium-based adhesive to make sintered balls, which are sent to a sintering kiln for melting and sintering, and then cooled to obtain sintered blocks; Step 5: crushing and grinding the sintered block to obtain a finished cement reinforced admixture.

2. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The fly ash is also mixed with slag material not exceeding 10% of the total fly ash.

3. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: In the step 1, the ratio of fly ash to water during slurrying is 2-3:1, and the amount of water added in the step 2 is 3-5 times the amount of fly ash in the step 1.

4. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The amount of the heavy metal chelating agent added in step 2 is 0.5-1.5% of the fly ash amount.

5. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The flocculant used in the step 2 is an anionic organic flocculant, and the amount of the flocculant added is 0.01-0.5% of the amount of fly ash added.

6. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The mixing ratio of the solid matter to the curing agent and the reducing powder in the step 4 is 6-10:2-4:

1.

7. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The components of the curing agent in step 4 are proportioned as follows by mass: 5-10 parts of kaolin, 30-40 parts of quartz powder / glass powder, 5-10 parts of borax, and 3-5 parts of calcium oxide.

8. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The reducing powder is a mixture of activated carbon powder and anthracite powder in any proportion.

9. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The clear liquid obtained from the secondary solid-liquid separation in step three is separated and desalted using a reverse osmosis device, and the concentrated brine obtained during the separation process is evaporated and crystallized to recover inorganic salts, and the clear liquid is reused.

10. The method for harmless deep utilization of fly ash from incineration of domestic waste according to claim 1, characterized in that: The end point of the grinding in step 5 is that the average particle size is no more than 500 meshes.