Washing-free sintering resourceful treatment method for household garbage incineration fly ash

Abstract

The invention discloses industrial solid waste treatment and resource utilization, and particularly relates to a washing-free sintering resource treatment method for household garbage incineration fly ash. Fly ash which is not washed with water, a silicon-aluminum hardening and tempering agent and solid fuel are mixed according to a specific proportion, granulated and sintered, and dioxin control and heavy metal directional migration are achieved through the temperature gradient of a material layer. According to the invention, low-temperature (1t, 150 DEG C) and low-pollution flue gas is shunted for common purification according to the temperature and component difference of flue gas at each sintering section, and dust (product dust) is returned for utilization; high-temperature (more than or equal to 150 DEG C) and high-pollution flue gas is divided for quenching and activated carbon deep purification, and dust (heavy metal concentrated ash) of the flue gas is sold for metallurgy. According to the invention, the fly ash washing link is thoroughly omitted, and the consumption of the adsorbent and the operation cost are greatly reduced while ultra-low emission is ensured through a flue gas quality-dividing and flow-dividing technology, so that low-cost, thorough harmlessness and high-value recycling of the fly ash are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial solid waste treatment and resource utilization, in particular to a water-washing-free sintering resource utilization treatment method for municipal solid waste incineration fly ash. BACKGROUND

[0002] Fly ash is listed as hazardous waste (HW18) due to its high concentration of heavy metals and dioxin pollutants. The current mainstream disposal methods are "water washing pretreatment + cement kiln co-disposal", "stabilization / solidification followed by safe landfill", "water washing pretreatment + low-temperature sintering + subsequent process", "water washing pretreatment + high-temperature sintering", and "water washing-free + high-temperature sintering or high-temperature melting in a rotary kiln". These technologies have inherent defects: the water washing process produces high-salinity wastewater that is difficult to dispose of, and the investment and operating costs are high; the landfill method occupies land resources and poses a long-term environmental risk, and does not achieve resource utilization; and the cost of high-temperature sintering or high-temperature melting in a rotary kiln is prohibitively high.

[0003] Directly incorporating fly ash into the steel sintering process has been explored, but faces two major bottlenecks: (1) the high chlorine content (10-20%) in fly ash leads to an increase in chlorine in sintered ash, which is not conducive to the production of subsequent ironmaking processes; and (2) some heavy metals in fly ash affect the product quality of subsequent ironmaking processes. Therefore, existing technologies require control of the total amount and elements of fly ash incorporation, resulting in poor feasibility and difficulty in popularization.

[0004] In addition, the traditional sintering flue gas treatment method is to mix all the flue gas extracted from the wind boxes in a large flue and then uniformly purify it. However, the flue gas characteristics of each wind box in the sintering process are not homogeneous: the flue gas at the front end is low in temperature (<150℃) and low in dust chloride and heavy metal content; the flue gas at the back end is high in temperature (≥150℃) and rich in volatilized heavy metal chlorides, which are the core source of pollutants. Mixing low-pollution flue gas with high-pollution flue gas and then uniformly treating it according to the highest standard is a huge waste of adsorbents and funds.

[0005] Therefore, it has become an urgent technical need in the field to develop a new fly ash disposal process and system that does not require water washing pretreatment, can simultaneously achieve complete harmless of pollutants, directional resource utilization of heavy metals, and significantly reduce the cost of end purification. SUMMARY

[0006] Due to the defects of the above-mentioned prior art, the present application aims to overcome these defects in the prior art and provide a municipal solid waste incineration fly ash sintering disposal method and system that has low investment and operating costs, does not require water washing pretreatment, can simultaneously achieve efficient decomposition of dioxins, sintering and solidification or directional enrichment and recovery of heavy metals, and can separate and purify flue gas according to its quality, thereby truly realizing an industrial method. The present application is realized by the following technical solutions: A waste incineration fly ash sintering recycling method without water washing, characterized in that it comprises the following steps: (1) mixing materials: The waste incineration fly ash, silicon-aluminum modifier and solid fuel are mixed in a mass ratio of 6-8:1-3:0.5-0.9, and then granulated after being wetted with water to obtain a sintering mixture; the silicon-aluminum modifier is one or more of waste incinerator slag, fly ash, coal gangue or waste asbestos; the solid fuel is one or more of coke powder, anthracite or waste activated carbon coal gangue; (2) preparing sintering: A layer of bottom material is first laid on the sintering machine trolley, and then the sintering mixture obtained in step (1) is laid on the bottom material, followed by ignition and sintering; the outlet of the sintering machine trolley is separately provided with a flue gas shunt and quality outlet and a high-temperature fly ash sintering material outlet; the flue gas shunt and quality outlet is further divided into a low-temperature flue dust outlet and a high-temperature flue dust outlet; the flue gas below 150℃ in the flue is shunted as low-temperature flue dust, and the flue gas above 150℃ in the flue is shunted as high-temperature flue dust; the material of the low-temperature flue dust outlet is mixed with the mixture of step (1); the high-temperature flue dust is discharged through the outlet and used for other purposes; the high-temperature fly ash sintering material is cooled, and the solid material is sieved and used as a finished product; the hot gas generated during the cooling process is discharged from the system for other purposes.

[0007] As a preferred embodiment, in step (1) of the method, the mixture is fed into a cylindrical mixer, wetted with water to a water content of 6-10%, and formed into spherical particles with a particle size of 1-3 mm.

[0008] As a preferred embodiment, in step (2) of the method, a bottom material with a thickness of 10-80 mm and a particle size of 5-20 mm is laid on the sintering machine; the bottom material is sintered ore return or gravel; as a more preferred embodiment, a mixture with a thickness of 400-1200 mm is laid on the bottom material; after ignition, the sintering is carried out under negative pressure, and the sintering end temperature is controlled below 400℃.

[0009] As a preferred embodiment, in the sintering process of step (2) of the method, the highest temperature of the combustion zone is controlled at 1000℃-1350℃, and the molar ratio of CaO / Cl - in the sintering mixture is greater than 1.2 to ensure that the water-soluble chloride content in the sintered product is less than 2%.

[0010] As a preferred embodiment, in step (2) of the method, the low-temperature flue dust is treated by a first bag filter at the outlet, and the collected dust is mixed with the mixture of step (1); the flue gas after dedusting is discharged after "semi-dry desulfurization + SCR denitrification".

[0011] As preferred, the cooling of the high-temperature fly ash sinter in step (2) of the above-mentioned processing method is rapid cooling to below 200 DEG C within 0.5 s, and the collected sinter is used as a finished product; the flue gas after the dust collector is treated by adsorption on an activated carbon bed before being discharged.

[0012] In the present application, in order to remove the environmental impact of pollutants, dioxin control is required in the sintering process: dioxin in the low-temperature wind box zone fly ash is completely decomposed in the combustion zone at >1000 DEG C at the upper part of the sintering layer; the decomposed flue gas is rapidly cooled when penetrating the lower part of the low-temperature material layer, and quickly passes through the dioxin recombination temperature range (250-450 DEG C), thereby inhibiting its reformation; the high-temperature wind box zone sintering layer has reached the bedding material, and the bedding material is a sintering product returned to the mill, and does not contain dioxin, and does not produce a dioxin decomposition reaction.

[0013] Heavy metal sintering solidification or migration enrichment: heavy metals in the fly ash are partially sintered and solidified at high temperatures, and partially gaseous chlorides, which migrate downward with the airflow, condense in the low-temperature material layer; with the downward movement of the combustion zone, the condensate is volatilized again, and undergoes multiple cycles of "volatilization-condensation-revolatilization", and this "distillation effect" ultimately drives the heavy metal chlorides to penetrate the bedding material layer and enter the flue gas; In the present application, the smoke is divided into two branches and subjected to a staged purification process: the process is monitored and divided in real time, the flue gas temperature of different wind boxes in the sintering machine is monitored in real time, and the flue gas is divided into at least a first flue gas branch with a temperature below 150 DEG C and a second flue gas branch with a temperature above 150 DEG C; The first flue gas branch is purified as follows: the flue gas of the first flue gas branch is introduced into a first bag filter, and the collected dust is returned to the batching system for recycling as a product with clean composition; the dusted flue gas is purified by a conventional desulfurization and denitrification process; The second flue gas branch is purified as follows: the flue gas of the second flue gas branch is introduced into a rapid cooling tower and rapidly cooled to below 200 DEG C within 0.5 s, and then introduced into a second bag filter; the collected dust is used for hydrometallurgical recovery of valuable metals as concentrated ash enriched with heavy metal chlorides; the dusted flue gas is subjected to deep desulfurization, denitrification and dioxin removal by an activated carbon process; The flue gas after purification of the two branches is combined and discharged from the chimney by the induced draft fan, meeting the environmental protection requirements.

[0014] The remaining products are resourceized: the produced sinter is used as a building material after passing the detection, ensuring no harm to the environment.

[0015] Advantages: Compared with the prior art, the present application has the following advantages: 1. Economy: The expensive and secondary pollution (high-salt wastewater) fly ash water washing pretreatment link is completely eliminated. Through the smoke quality and quantity separation technology, only about 30-40% of the high-pollution flue gas is deeply purified by using expensive activated carbon, which can save 40%-70% of the activated carbon consumption, and has absolute economic advantages.

[0016] 2. Harmless: Through the dual mechanism of high-temperature decomposition and in-situ rapid cooling, the decomposition and inhibition of dioxin recombination are fundamentally solved.

[0017] 3. High degree of resource utilization: The sintered product (Cl - <3%) meets the general solid waste requirements and can be used as a building material resource. The dispersed heavy metals are concentrated in a small amount of dust, forming a high-grade "artificial rich ore". Through the separation technology, fine classification of dust is achieved: product dust (low pollution) is recycled internally, and concentrated ash (high pollution, high value) is sold to metallurgy externally, maximizing resource utilization efficiency.

[0018] 4. Reliable and intelligent process: The core equipment is a mature steel sintering machine with low technical risk. The automatic quality and quantity separation system based on temperature sensors is intelligent and efficient, easy to industrialize. DETAILED DESCRIPTION

[0019] The following will make a specific description of the implementation of the present application Example 1

[0020] A sintering production line for treating 100,000 tons of fly ash from municipal solid waste incineration per year is built in a certain place. It includes two steps of mixing materials and preparing sintering: (1) Mixing materials: According to the mass percentage, the fly ash (65%) without water washing, fly ash (28%), and anthracite (7%) are accurately proportioned by a belt scale, mixed uniformly, and wet granulated by adding 10% water to obtain sintering mixture and form spherical objects with a particle size of 2 mm; (2) Preparing sintering: A 60 mm thick bottom layer with a particle size of 10 mm is laid on the sintering machine, and the bottom layer is sintered or crushed stone; then ignition sintering is carried out; The outlet of the sintering machine trolley is divided into a flue gas separation and quality separation outlet and a high-temperature fly ash sintering outlet; the flue gas separation and quality separation outlet is further divided into a low-temperature flue dust outlet and a high-temperature flue dust outlet; the flue gas below 150℃ in the flue is separated as low-temperature flue dust, and the flue gas above 150℃ in the flue is separated as high-temperature flue dust; the material of the low-temperature flue dust outlet is mixed with the mixture of step (1); the high-temperature flue dust is discharged through the outlet and used for other purposes; the high-temperature fly ash sintering material is cooled and then screened to obtain solid material for use as a finished product; the hot gas generated during the cooling process is discharged from the system for other purposes.

[0021] Finally, the fly ash treated by the present application is discharged, which no longer has harm to the environment, and the waste can be utilized. Example 2

[0022] A sintering production line for treating 100,000 tons of household waste incineration fly ash per year is constructed in a certain place, and the production line includes two process steps: (1) Mixing materials: The materials are proportioned by mass percentage, and the fly ash without water washing (70%), incineration slag (23%), and coke powder (7%) are accurately proportioned by a belt scale. Then, the mixed materials are sent into a cylinder mixer, wetted with water to about 8% moisture, and formed into small balls of 2 or 3 mm in diameter.

[0023] (2) Preparing sintering: First, the materials are laid and sintered: on a 28 m² sintering machine, 50 mm thick sintering ore return material with a particle size of 5-20 mm is laid as a bottom material, and then 700 mm thick mixed materials prepared in step (1) are laid. After ignition, the sintering is carried out under negative pressure, and the sintering end temperature is controlled below 400℃.

[0024] In this process, the flue gas is divided and treated according to its quality: The operation of dividing: through the temperature sensor arranged on the branch pipe of the wind box, the flue gas (about 65% of the total air volume) from the front low-temperature wind box (40-150℃) is introduced into the first purification branch, and the flue gas (about 35% of the total air volume) from the rear high-temperature wind box (150-400℃) is introduced into the second purification branch.

[0025] Graded purification: First branch: the low-temperature flue gas passes through the first bag filter, and the collected dust (0.5 t / h) is returned to the proportioning system. After dust removal, the flue gas is discharged after "semi-dry desulfurization + SCR denitration".

[0026] Second branch: the high-temperature flue gas passes through the quenching tower (cooled to 180℃ within 0.5 s) and the second bag filter, and the concentrated ash (about 0.2 t / h, rich in Pb, Zn, and Cd) is sold to the metallurgical industry. After dust removal, the flue gas is deeply purified by activated carbon bed adsorption.

[0027] The purified gas from the two branches is combined and discharged through the chimney.

[0028] Final product disposal: the sintered ore is used as a building material raw material. The concentrated ash is sold, achieving the purpose of overall harmlessness. After being treated according to the present application, there is obvious economic efficiency: the direct cost of treating one ton of fly ash by this process is about 320 yuan, and about 3000 tons of activated carbon can be saved per year due to the quality division and flow division technology, saving operating costs of more than 15 million yuan, and the economic and environmental benefits are extremely significant. Example 3

[0029] The same mixture as in Example 2 (step 1) is laid on the sintering pallet, and then a layer of bedding material is laid on the pallet, and then the sintering mixture obtained in step (1) is laid on the bedding material, and then ignition and sintering are carried out; a flue gas shunt and a high-temperature fly ash sintered material outlet are arranged at the outlet of the sintering pallet; the flue gas shunt and the high-temperature fly ash sintered material outlet are further divided into a low-temperature flue dust outlet and a high-temperature flue dust outlet; the flue gas below 150℃ in the flue is shunted as low-temperature flue dust, and the flue gas above 150℃ in the flue is shunted as high-temperature flue dust; the material in the low-temperature flue dust outlet is mixed with the mixture in step (1); the high-temperature flue dust is discharged through the outlet and used for other purposes; The high-temperature fly ash sintered material is cooled, and the solid material is sieved and used as finished product ore; the hot gas generated during cooling is discharged from the system for other purposes.

[0030] During sintering, a bedding material with a thickness of 20mm and a particle size of 15mm is laid on the sintering pallet, and the bedding material is gravel. After ignition, the sintering is carried out under negative pressure, and the sintering end temperature is controlled below 400℃.

[0031] At the same time, during sintering, the highest temperature of the combustion zone is controlled between 1200℃-1300℃, and the molar ratio of CaO / Cl⁻ in the sintering mixture is greater than 1.2, to ensure that the content of water-soluble chloride ions in the sintered final product is less than 2%.

[0032] In the shunt operation: through the temperature sensor arranged on the air box branch pipe, the flue gas (about 65% of the total air volume) from the front low-temperature air box (below 150℃) is introduced into the first purification branch; the flue gas (about 35% of the total air volume) from the rear high-temperature air box (above 150℃ and below 400℃) is introduced into the second purification branch.

[0033] The specific process of grading purification is as follows: First branch: low-temperature flue gas passes through the first bag filter, and the collected dust (0.5t / h) is returned to the batching system. After dust removal, the flue gas is discharged after "semi-dry desulfurization + SCR denitration".

[0034] Second branch: high-temperature flue gas passes through the quench tower (cooled to 180℃ within 0.5s) and the second bag filter, and the collected concentrated ash (about 0.2t / h, rich in Pb, Zn, Cd) is sold to metallurgy. After dust removal, the flue gas is deeply purified by "activated carbon bed adsorption".

[0035] The purified gas from the two branches is combined and discharged through the chimney. The economic effect of this embodiment can also achieve better value compared to the prior art.

Claims

1. A water-washing-free sintering resourceful treatment method for municipal solid waste incineration fly ash, characterized in that, The method comprises the following steps: (1) mixing materials: The household waste incineration fly ash, the silicon-aluminum modifier, and the solid fuel are mixed according to a mass ratio of 6-8:1-3:0.5-0.9, and then granulated after being wetted with water to obtain sintered mixture; the silicon-aluminum modifier is one or more of household waste incinerator slag, fly ash, coal gangue, or waste asbestos; the solid fuel is one or more of coke powder, anthracite, or waste activated carbon coal gangue; (2) preparing sintering: A layer of bottoming material is first laid on the sintering machine trolley, and then the sintered mixture obtained in step (1) is laid on the bottoming material, and then ignition sintering is performed; The outlet of the sintering machine trolley is separately provided with a flue gas shunt and quality outlet and a high-temperature fly ash sintered material outlet; the flue gas shunt and quality outlet is further divided into a low-temperature flue dust outlet and a high-temperature flue dust outlet; the flue gas below 150 DEG C in the flue is shunted as low-temperature flue dust, and the flue gas above 150 DEG C in the flue is shunted as high-temperature flue dust; the material of the low-temperature flue dust outlet is mixed with the mixture of step (1); the high-temperature flue dust is discharged through the outlet and used for other purposes; The high-temperature fly ash sintered material is cooled, and the solid material is screened and used as finished product ore; the hot gas generated during the cooling process is discharged from the system and used for other purposes.

2. A process according to claim 1, characterized in that, The mixture in step (1) is sent to a cylindrical mixer, wetted with water to a water content of 6-10%, and formed into spherical particles with a particle size of 1-3 mm.

3. The method of claim 1, wherein, In step (2), the bottoming material with a thickness of 10-80 mm and a particle size of 5-20 mm is laid on the sintering machine; the bottoming material is sintered ore return or gravel.

4. A method of treatment according to claim 3, wherein, The mixture with a thickness of 400-1200 mm is laid on the bottoming material; after ignition, the sintering is performed under negative pressure, and the final sintering temperature is controlled below 400 DEG C.

5. The method of claim 1, wherein, In the sintering process of step (2), the highest temperature of the combustion zone is controlled at 1000°C-1350°C, and the molar ratio of CaO / C1 - in the sintering mixture is controlled to be greater than 1.2 to ensure that the water-soluble chloride ion content in the final sintered product is less than 2%.

6. The method of claim 1, wherein, In step (2), the low-temperature flue dust is treated by a first bag dust collector at the outlet, and the collected dust removal ash is mixed with the mixture of step (1); the flue gas after dust removal is discharged after being treated by "semi-dry desulfurization + SCR denitration".

7. The method of claim 1, wherein, In step (2), the high-temperature fly ash sintered material is cooled to below 200 DEG C within 0.5 s, and the sintered material is collected and used as finished product ore; the flue gas after the dust collector is discharged after being treated by an activated carbon bed.