阅读说明：本技术 一种烧结协同处置垃圾焚烧飞灰过程中二恶英控制方法 (Method for controlling dioxin in process of sintering and co-processing waste incineration fly ash ) 是由 卢四平 汤明慧 徐莉 陆胜勇 钟伟 何豪 许醴鸣 于 2021-07-26 设计创作，主要内容包括：本发明公开了一种烧结协同处置垃圾焚烧飞灰过程中二恶英控制方法,首先将垃圾焚烧飞灰、石灰乳和硫脲混合造粒后得到飞灰小球；然后将飞灰小球与铁矿烧结原料混合均匀后得到混合料,布料,在混合料料面点火,点火温度为1000～1150℃,在混合料底部抽风条件下烧结,烧结最高温度为1200～1350℃,控制烧结过程中的升温速率不低于220℃/min。该方法在保证烧结矿品质和产量的前提下,实现飞灰的有效处置及飞灰中二恶英的高效降解,实现垃圾焚烧飞灰的高效清洁处置,同时抑制烧结过程中二恶英的从头合成,实现真正意义上的飞灰无害化资源化处置。(The invention discloses a dioxin control method in the process of sintering and co-processing waste incineration fly ash, which comprises the steps of mixing and granulating waste incineration fly ash, lime milk and thiourea to obtain fly ash pellets; and then uniformly mixing the fly ash pellets with the iron ore sintering raw material to obtain a mixture, distributing the mixture, igniting the mixture on the surface of the mixture, wherein the ignition temperature is 1000-1150 ℃, sintering the mixture under the condition of air draft at the bottom of the mixture, the highest sintering temperature is 1200-1350 ℃, and the heating rate in the sintering process is controlled to be not lower than 220 ℃/min. The method realizes effective treatment of the fly ash and efficient degradation of dioxin in the fly ash on the premise of ensuring the quality and yield of the sintered ore, realizes efficient clean treatment of the waste incineration fly ash, simultaneously inhibits the de novo synthesis of dioxin in the sintering process, and realizes the harmless resource treatment of the fly ash in the true sense.)

1. A dioxin control method in the process of sintering and co-processing waste incineration fly ash is characterized by comprising the following steps:

(1) mixing and granulating the waste incineration fly ash, lime milk and thiourea to obtain fly ash pellets;

(2) and uniformly mixing the fly ash pellets with an iron ore sintering raw material to obtain a mixture, distributing the mixture, igniting the mixture on the surface of the mixture, wherein the ignition temperature is 1000-1150 ℃, sintering the mixture under the condition of air draft at the bottom of the mixture, the highest sintering temperature is 1200-1350 ℃, and the heating rate in the sintering process is controlled to be not lower than 220 ℃/min.

2. The method for controlling dioxin during the fly ash incineration process of the waste incineration in the sintering cooperative disposal manner according to claim 1, wherein in the step (1), the lime milk is measured by CaO and accounts for 50-66% of the mass of the fly ash pellets; and/or

In the step (1), the purity of the thiourea is more than or equal to 99%, and the thiourea is in an industrial grade and accounts for 0.1-2.5% of the mass of the fly ash pellets.

3. The method for controlling dioxin during sintering co-disposal of fly ash from waste incineration according to claim 1, wherein in the step (1), the chlorine content of the fly ash from waste incineration is less than 0.5 wt%, and the water content is less than 5 wt%.

4. The method for controlling dioxin during co-fired waste incineration fly ash sintering treatment according to claim 3, wherein the waste incineration fly ash is subjected to secondary countercurrent water washing and drying treatment, and has a chlorine content of less than 0.5 wt% and a water content of less than 5 wt%.

5. The method for controlling dioxin during co-fired waste incineration fly ash disposal according to claim 4, wherein the water-ash ratio is controlled to be 2: 1-4: 1 during the secondary countercurrent water washing; and/or

In the drying treatment, the drying temperature is controlled to be 100-120 ℃, and the drying time is 60-90 min.

6. The method for controlling dioxin during co-firing and disposal of waste incineration fly ash according to claim 1, wherein in the step (1), the particle size of the fly ash pellets is 4 to 8 mm.

7. The method for controlling dioxin during the process of co-firing and disposing waste incineration fly ash according to claim 1, wherein in the step (2), the mass of the fly ash pellets accounts for 1 to 3 wt% of the mass of the iron ore sintering raw material.

8. The method for controlling dioxin during co-fired waste incineration fly ash disposal according to claim 1, wherein in the step (2), the iron ore sintering raw material includes iron ore, limestone/quicklime, coke and return fines.

9. The method for controlling dioxin during the process of sintering co-disposal of fly ash from waste incineration according to any one of claims 1 to 8, wherein in the step (2), after the sintering treatment, the degradation rate of dioxin contained in the fly ash from waste incineration is greater than 94%.

Technical Field

The invention belongs to the field of fly ash disposal, and particularly relates to a dioxin control method in a process of sintering and co-disposing waste incineration fly ash.

Background

According to the annual book of statistics in China, the clearing amount of urban domestic garbage in 2017 in China is as high as 21520 ten thousand tons, compared with 2016, the clearing amount is increased by 5.69%, the harmless treatment rate of the domestic garbage reaches 97.7%, and the annual treatment capacity of garbage incineration is remarkably increased from 2599 ten thousand tons/year to 8463 ten thousand tons/year in 5 years of 2011-one-year 2017. The waste incineration disposal rate will continuously rise, and along with the continuous enlargement of the construction and proposed scale, the fly ash problem brought by the method is not ignored while the problem of 'waste surrounding city' is solved. As the fly ash contains easily leached heavy metals and trace persistent organic pollutant dioxin, the fly ash is listed in national hazardous waste records in China, belongs to HW18 hazardous wastes, and causes air pollution and adverse effect on human beings if the hazardous wastes are not effectively treated, thereby restricting the development of waste incineration power generation.

The prior fly ash disposal mainly depends on the synergy of cement chelation solidification and a cement kiln, wherein the cement solidification can inhibit the leaching of heavy metals in the fly ash but can not degrade dioxin in the fly ash, and the solidified fly ash has obvious capacity increase, is not beneficial to transportation and landfill, and does not have the condition of subsequent resource utilization. The cement kiln cooperative treatment is a main mode for recycling the fly ash, but because the chlorine is strictly controlled by cement, the addition amount of the fly ash is very low, so that the cement kiln can only realize the recycling of limited fly ash; china actively encourages domestic waste incineration power generation on a policy level, however, the lack of reasonable fly ash disposal technology becomes one of important factors restricting the development of the waste incineration power generation industry.

Chinese patent CN 107159678B discloses a dioxin control method in the process of iron ore sintering synergistic disposal of waste incineration fly ash, which comprises mixing, granulating and drying four components of waste fly ash, lime milk, combustible solid fuel and sludge to prepare pellets, uniformly mixing the pellets with sintering raw materials for preparing the pellets, distributing the materials, igniting and sintering; although the method realizes the high-efficiency degradation of the dioxin in the fly ash, ensures the effective consolidation of the garbage fly ash and realizes the clean treatment of the garbage fly ash, the Cl and Cu in the fly ash are introduced in the sintering process, the dioxin can be synthesized again from the beginning in the sintering process, if the treatment is not proper, the harm of the dioxin in the fly ash can not be eliminated, and the total discharge amount of the dioxin in the sintering flue gas can be increased.

In view of the above circumstances, there is a need in the art to develop a method for treating fly ash from waste incineration by using a sintering process in cooperation, which can efficiently degrade dioxin in fly ash during the sintering process, and simultaneously inhibit the de novo synthesis of dioxin during the sintering process, thereby realizing the harmless recycling treatment of fly ash in a real sense.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a method for controlling dioxin in the process of sintering and co-disposing waste incineration fly ash, which realizes effective disposal of fly ash and efficient degradation of dioxin in fly ash on the premise of ensuring the quality and yield of sintered ore, realizes efficient clean disposal of waste incineration fly ash, simultaneously inhibits the de novo synthesis of dioxin in the sintering process, and realizes harmless recycling disposal of fly ash in the real sense.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a dioxin control method in the process of sintering and co-processing waste incineration fly ash, which comprises the following steps:

(1) mixing and granulating the waste incineration fly ash, lime milk and thiourea to obtain fly ash pellets;

(2) and uniformly mixing the fly ash pellets with an iron ore sintering raw material to obtain a mixture, distributing the mixture, igniting the mixture on the surface of the mixture, wherein the ignition temperature is 1000-1150 ℃, sintering the mixture under the condition of air draft at the bottom of the mixture, the highest sintering temperature is 1200-1350 ℃, and the heating rate in the sintering process is controlled to be not lower than 220 ℃/min.

Preferably, in the step (1), the lime milk is measured by CaO and accounts for 50-66% of the mass of the fly ash pellets; and/or

In the step (1), the purity of the thiourea is more than or equal to 99%, and the thiourea is in an industrial grade and accounts for 0.1-2.5% of the mass of the fly ash pellets.

Preferably, in the step (1), the chlorine content of the waste incineration fly ash is lower than 0.5 wt%, and the water content is lower than 5 wt%.

Preferably, after the waste incineration fly ash is subjected to secondary countercurrent washing and drying treatment, the chlorine content is lower than 0.5 wt%, and the water content is lower than 5 wt%.

Preferably, the water-cement ratio is controlled to be 2: 1-4: 1 in the secondary countercurrent washing process; and/or

In the drying treatment, the drying temperature is controlled to be 100-120 ℃, and the drying time is 60-90 min.

Preferably, in the step (1), the particle size of the fly ash pellets is 4-8 mm.

Preferably, in the step (2), the mass of the fly ash pellets accounts for 1-3 wt% of the mass of the iron ore sintering raw material.

Preferably, in the step (2), the iron ore sintering raw material includes iron ore, limestone/quicklime, coke, and return ores.

Preferably, in the step (2), after the sintering treatment, the degradation rate of dioxin contained in the waste incineration fly ash is greater than 94%.

The method for controlling dioxin in the process of sintering and co-processing waste incineration fly ash provided by the invention also has the following beneficial effects:

1. according to the dioxin control method in the process of sintering and disposing the waste incineration fly ash cooperatively, the fly ash is disposed by utilizing the high-temperature sintering process of the iron ore, so that the normal sintering of the iron ore is realized, the fly ash is effectively and safely disposed, particularly, the dioxin in the fly ash can be degraded, the activity of a metal catalyst in the fly ash is inhibited, and the fly ash is inhibited from synthesizing dioxin from the beginning in the sintering process; the method has the following specific advantages: 1) On the premise of not influencing sintering indexes, the fine garbage incineration fly ash is consolidated into blocks under the high-temperature condition in the sintering process; 2) CaO, Ca (OH) in fly ash₂Is a good fluxing agent, and realizes the resource utilization of the fly ash; 3) dioxin in the fly ash is efficiently degraded; 4) the introduction of the fly ash can not cause the increase of pollutant discharge types in the sintering process, and a tail flue gas treatment device does not need to be changed;

2. the method for controlling dioxin in the process of sintering and co-processing waste incineration fly ash, disclosed by the invention, prepares the pretreated waste incineration fly ash, lime milk and thiourea into fly ash pellets, and regulates and controls the components so that the components are efficiently matched: the addition of lime milk increases the CaO content of the fly ash pellets, so that the fly ash pellets can generate enough liquid phase to be consolidated at high temperature, and meanwhile, the excessive CaO can be combined with HCl and Cl in the sintering process₂Reacting to reduce chlorine source needed by dioxin generation; thiourea as S, N composite inhibitor is added into the fly ash pellet A in proper amount to react with the chlorides of Cu, Fe, etc. on the fly ash surface effectively and to react with CuCl with strongest catalytic activity₂Conversion to CuSO with weaker catalytic activity₄The de novo synthesis of dioxin is inhibited and NH generated by decomposition of thiourea is simultaneously inhibited₃Reacting with HCl in the sintering process to form NH₄Cl, further reduces the chlorine source required for dioxin generation, and in addition, Cu ions react with NH₃Forming a complex, and inhibiting the generation of dioxin again through metal catalyst poisoning; therefore, the reaction conditions in the fly ash incineration process are optimized in the aspects of small ball composition, retardant and the like, so that the high-efficiency degradation of dioxin in the fly ash is realized, and the de novo synthesis of dioxin in the sintering process is inhibited.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic flow chart of a dioxin control method in the process of sintering and co-processing waste incineration fly ash according to the invention.

Detailed Description

In order to better understand the technical solutions of the present invention, the following further describes the technical solutions of the present invention with reference to the accompanying drawings and examples.

Referring to fig. 1, the method for controlling dioxin during the process of co-processing waste incineration fly ash by sintering provided by the invention comprises the following steps:

(1) mixing and granulating the waste incineration fly ash, lime milk and thiourea to obtain fly ash pellets;

the specific process is as follows: firstly, performing secondary countercurrent washing and drying treatment on the waste incineration fly ash to obtain the waste incineration fly ash with the chlorine content of less than 0.5 wt% and the water content of less than 5 wt%, controlling the water-ash ratio to be 2: 1-4: 1 in the secondary countercurrent washing process, and controlling the drying temperature to be 100-120 ℃ and the drying time to be 60-90 min in the drying treatment process; then uniformly mixing the treated waste incineration fly ash with lime milk and thiourea, and granulating to obtain fly ash pellets, wherein the lime milk is measured by CaO and accounts for 50-66% of the mass of the fly ash pellets; the purity of thiourea is more than or equal to 99 percent, and the thiourea is of industrial grade and accounts for 0.1-2.5 percent of the mass of the fly ash pellets; the particle size of the prepared fly ash pellets is controlled to be 4-8 mm, and the smaller comparative area reduces the contact points of the waste incineration fly ash and the iron ore sintering raw materials, namely the catalytic sites for generating dioxin are reduced, and the probability of generating dioxin is reduced;

(2) uniformly mixing the fly ash pellets with the iron ore sintering raw material to obtain a mixture, distributing the mixture, igniting the mixture on the surface of the mixture, wherein the ignition temperature is 1000-1150 ℃, sintering the mixture under the condition of air draft at the bottom of the mixture, the highest sintering temperature is 1200-1350 ℃, and the heating rate in the sintering process is controlled to be not lower than 220 ℃/min.

The specific process is as follows: uniformly mixing the fly ash pellets prepared in the step (1) with an iron ore sintering raw material to obtain a mixture, and then carrying out ignition and sintering treatment on the obtained mixture after material distribution; wherein the mass of the fly ash pellets accounts for 1-3 wt% of the mass of the iron ore sintering raw material; the iron ore sintering raw materials comprise iron ore, limestone/quicklime, coke, return fines and the like; igniting the mixture on the charge level during ignition, and controlling the ignition temperature to be 1000-1150 ℃; and during sintering treatment, the sintering is carried out under the condition of air draft at the bottom of the mixture, the highest sintering temperature is 1200-1350 ℃, and the heating rate of the mixture is controlled to be not lower than 220 ℃/min by controlling the negative air draft pressure and the material layer air permeability of the mixture. After the sintering treatment is finished, the emission reduction rate of the dioxin in the flue gas reaches more than 50 percent, and the degradation rate of the dioxin contained in the waste incineration fly ash is more than 94 percent.

In the process, in the step (1), most soluble chlorine salt in the waste incineration fly ash is removed after secondary countercurrent washing, the chlorine content is reduced to be below 0.5%, the introduction of chlorine element is greatly reduced, then the waste incineration fly ash after drying treatment can be rapidly heated in the subsequent sintering process, dioxin can be rapidly decomposed at high temperature, and the high-efficiency degradation of the dioxin is realized. Proper amount of lime milk, thiourea, etc. is mixed with garbage incinerating flyash for pelletizing, and the added lime milk raises the CaO content in the flyash pellet to make the flyash pellet capable of producing enough liquid phase at high temperature for solidification and excessive CaO capable of being mixed with HCl and Cl in the subsequent sintering process₂Reacting to reduce chlorine source needed by dioxin generation; thiourea as S, N composite inhibitor is added into the fly ash pellet to react with the chlorides of Cu, Fe, etc. on the fly ash surface effectively and to react with CuCl with strongest catalytic activity₂Conversion to CuSO with weaker catalytic activity₄The de novo synthesis of dioxin is inhibited and NH generated by decomposition of thiourea is simultaneously inhibited₃Reacting with HCl in the sintering process to form NH₄Cl, further reduces the chlorine source required for dioxin generation, and in addition, Cu ions react with NH₃Complex formation and the inhibition of dioxin regeneration through the poisoning of metal catalyst. By the pelletizing formula, volatilization and secondary generation of dioxin can be effectively reduced, so that high-efficiency degradation of dioxin in fly ash is realized, and generation of dioxin in the sintering process is inhibited. In addition, the reaction time of the fly ash from the waste incineration for synthesizing the dioxin from the beginning is about 1-5 s, the optimal temperature for synthesizing the dioxin from the beginning by the solid incineration is 300-350 ℃, the temperature rise rate of the mixture is increased by means of bottom air draft, the transmission rate from a high temperature zone to the lower part (1200-1350 ℃) in the sintering process is increased, and the sintering time is shortened, so that the secondary generation of the dioxin is reduced.

In addition, an air draft sintering method is adopted in the step (2), firstly, a sintering material layer is ignited at the temperature of 1000-1150 ℃, after the fuel in the mixture is ignited, the high-temperature zone of fuel combustion is gradually transferred from the surface of the material layer to the material layer under the action of air draft, the sintering process is sequentially completed, the highest sintering temperature is required to be 1200-1350 ℃, and the sintering temperature rise rate is not lower than 220 ℃/min.

The dioxin control method in the process of the invention for sintering and co-disposing the fly ash from waste incineration is further described with reference to specific examples; the reagents and materials used in the following examples are commercially available products or products that are publicly known.

TABLE 1 sintering raw material ratio

Datum

The iron ore sintering raw materials shown in the table 1 are adopted, ignition and sintering are carried out after material distribution, the ignition temperature is controlled to be 1150 ℃, the sintering maximum temperature is 1350 ℃, the heating rate is 240 ℃/min, and the final sintering index is shown in the table 2.

Comparative example 1: direct addition of waste incineration fly ash

Drying the waste incineration fly ash until the water content is less than 5 wt%, then preparing fly ash pellets with the granularity of 6mm, then uniformly mixing the fly ash pellets with the iron ore sintering raw material shown in table 1 to obtain a mixture, wherein the mass of the fly ash pellets is 3% of that of the iron ore sintering raw material, igniting and sintering the obtained mixture after distributing, controlling the ignition temperature to 1150 ℃, the maximum sintering temperature to 1350 ℃, the heating rate to 240 ℃/min, and the final sintering index shown in table 2.

Comparative example 2: the waste incineration fly ash is directly added after being washed by water

Performing secondary countercurrent washing on the waste incineration fly ash, and controlling the water-ash ratio to be 3: 1, filter-pressing the garbage incineration fly ash after washing, drying for 90min at 100 ℃ (drying until the water content is less than 5 wt%), preparing fly ash pellets with the granularity of 6mm, uniformly mixing the fly ash pellets with the iron ore sintering raw materials shown in table 1 to obtain a mixture, wherein the mass of the fly ash pellets is 3% of that of the iron ore sintering raw materials, distributing the mixture, igniting and sintering, controlling the ignition temperature to 1150 ℃, the sintering maximum temperature to 1350 ℃, the heating rate to 240 ℃/min, and the final sintering index shown in table 2.

Example 1

Performing secondary countercurrent washing on the waste incineration fly ash, and controlling the water-ash ratio to be 3: 1, filter-pressing the garbage incineration fly ash after washing, drying for 90min at 100 ℃ (the chlorine content is lower than 0.5 wt% after washing, and the water content is less than 5% after drying), then uniformly mixing the garbage incineration fly ash with lime milk and thiourea, and preparing fly ash pellets with the particle size of 6mm, wherein the lime milk (measured by CaO) accounts for 50% of the mass of the fly ash pellets, and the thiourea accounts for 0.1% of the mass of the fly ash pellets; then uniformly mixing the prepared fly ash pellets with the iron ore sintering raw materials shown in the table 1 to obtain a mixture, wherein the mass of the fly ash pellets is 2 percent of that of the iron ore sintering raw materials, the obtained mixture is ignited and sintered after being distributed, the ignition temperature is controlled to be 1100 ℃, the highest sintering temperature is 1300 ℃, the heating rate is 220 ℃/min, the sintering indexes and the dioxin degradation effects in the waste incineration fly ash and in the flue gas are shown in the table 2, it can be known that the washed and dried fly ash from waste incineration can be added to the sintering process to obtain the sintering index equivalent to the standard, the degradation rate of dioxin in the fly ash from waste incineration is 94.56%, the dioxin content in the flue gas is reduced by 50.47%, compared with the method of directly adding fly ash or adding fly ash after washing and sintering in the sintering process, the method of the embodiment, can greatly improve the degradation rate of dioxin in the waste incineration fly ash in the sintering process and inhibit the re-synthesis of dioxin in the sintering process.

Example 2

Performing secondary countercurrent washing on the waste incineration fly ash, and controlling the water-ash ratio to be 3: 1, filter-pressing the garbage incineration fly ash after washing, drying for 90min at 100 ℃ (the chlorine content is lower than 0.5 wt% after washing, and the water content is less than 5% after drying), then uniformly mixing the garbage incineration fly ash with lime milk and thiourea, and preparing fly ash pellets with the particle size of 6mm, wherein the lime milk (measured by CaO) accounts for 50% of the mass of the fly ash pellets, and the thiourea accounts for 2.5% of the mass of the fly ash pellets; then, the prepared fly ash pellets are uniformly mixed with the iron ore sintering raw material shown in table 1 to obtain a mixture, the mass of the fly ash pellets is 3% of that of the iron ore sintering raw material, the obtained mixture is subjected to ignition and sintering after distribution, the ignition temperature is controlled to 1150 ℃, the sintering highest temperature is 1350 ℃, the temperature rise rate is 240 ℃/min, the sintering index and the dioxin degradation effect in the waste incineration fly ash and in the flue gas are shown in table 2, it can be known that the sintering index equivalent to the reference can be obtained by adding the washed and dried waste incineration fly ash into the sintering process, the degradation rate of the dioxin contained in the waste incineration fly ash is 96.37%, the dioxin content in the flue gas is reduced by 51.98%, compared with the method in the embodiment of directly adding the waste incineration fly ash or adding the washed and sintering process for sintering, the degradation rate of the dioxin in the waste incineration fly ash in the sintering process can be greatly improved, and inhibit the re-synthesis of dioxin during sintering.

Example 3

Performing secondary countercurrent washing on the waste incineration fly ash, and controlling the water-ash ratio to be 3: 1, filter-pressing the garbage incineration fly ash after washing, drying for 90min at 100 ℃ (the chlorine content is lower than 0.5 wt% after washing, and the water content is less than 5% after drying), then uniformly mixing the garbage incineration fly ash with lime milk and thiourea, and preparing fly ash pellets with the particle size of 6mm, wherein the lime milk (measured by CaO) accounts for 66% of the mass of the fly ash pellets, and the thiourea accounts for 2.5% of the mass of the fly ash pellets; then, the prepared fly ash pellets and the iron ore sintering raw material shown in table 1 are uniformly mixed to obtain a mixture, the mass of the fly ash pellets is 3% of that of the iron ore sintering raw material, the obtained mixture is subjected to ignition and sintering after distribution, the ignition temperature is controlled to 1150 ℃, the sintering highest temperature is 1350 ℃, the temperature rise rate is 240 ℃/min, the sintering index and the dioxin degradation effect in the waste incineration fly ash and in the flue gas are shown in table 2, it can be known that the sintering index equivalent to the reference can be obtained by adding the washed and dried waste incineration fly ash into the sintering process, the degradation rate of the dioxin in the waste incineration fly ash is 96.64%, the dioxin content in the flue gas is reduced by 52.68%, compared with the method of directly adding the waste incineration fly ash or adding the washed and then sintering process, the method in the embodiment can greatly improve the dioxin degradation rate in the waste incineration fly ash in the sintering process, and inhibit the re-synthesis of dioxin during sintering.

Example 4

Performing secondary countercurrent washing on the waste incineration fly ash, and controlling the water-ash ratio to be 2:1, filter-pressing the garbage incineration fly ash after washing, drying for 60min at 120 ℃ (the chlorine content is lower than 0.5 wt% after washing, and the water content is less than 5% after drying), then uniformly mixing the garbage incineration fly ash with lime milk and thiourea, and preparing fly ash pellets with the particle size of 6mm, wherein the lime milk (measured by CaO) accounts for 55% of the mass of the fly ash pellets, and the thiourea accounts for 1.5% of the mass of the fly ash pellets; then, the prepared fly ash pellets are uniformly mixed with the iron ore sintering raw material shown in table 1 to obtain a mixture, the mass of the fly ash pellets is 2% of that of the iron ore sintering raw material, the obtained mixture is subjected to ignition and sintering after distribution, the ignition temperature is controlled to be 1000 ℃, the sintering highest temperature is 1200 ℃, the temperature rise rate is 250 ℃/min, the sintering index and the dioxin degradation effect in the waste incineration fly ash and in the flue gas are shown in table 2, it can be known that the sintering index equivalent to the reference can be obtained by adding the washed and dried waste incineration fly ash into the sintering process, the degradation rate of the dioxin contained in the waste incineration fly ash is 96.22%, the dioxin content in the flue gas is reduced by 51.76%, compared with the method in the embodiment that the waste incineration fly ash is directly added or added into the sintering process after being washed, the degradation rate of the dioxin in the waste incineration fly ash in the sintering process can be greatly improved, and inhibit the re-synthesis of dioxin during sintering.

Example 5

Performing secondary countercurrent washing on the waste incineration fly ash, and controlling the water-ash ratio to be 4:1, filter-pressing the garbage incineration fly ash after washing, drying for 75min at 110 ℃ (the chlorine content is lower than 0.5 wt% after washing, and the water content is less than 5% after drying), then uniformly mixing the garbage incineration fly ash with lime milk and thiourea, and preparing fly ash pellets with the particle size of 6mm, wherein the lime milk (measured by CaO) accounts for 60% of the mass of the fly ash pellets, and the thiourea accounts for 2.0% of the mass of the fly ash pellets; then, the prepared fly ash pellets and the iron ore sintering raw material shown in table 1 are uniformly mixed to obtain a mixture, the mass of the fly ash pellets is 2.5% of that of the iron ore sintering raw material, the obtained mixture is subjected to ignition and sintering after being distributed, the ignition temperature is controlled to be 1150 ℃, the highest sintering temperature is 1300 ℃, the heating rate is 260 ℃/min, the sintering index and the dioxin degradation effect in the waste incineration fly ash and in the flue gas are shown in table 2, it can be known that the sintering index equivalent to the reference can be obtained by adding the washed and dried waste incineration fly ash into the sintering process, the degradation rate of the dioxin contained in the waste incineration fly ash is 96.44%, the dioxin content in the flue gas is reduced by 52.38%, compared with the method in the embodiment that the waste incineration fly ash is directly added or added into the sintering process after being washed, the degradation rate of the dioxin in the waste incineration fly ash in the sintering process can be greatly improved, and inhibit the re-synthesis of dioxin during sintering.

TABLE 2 sintering index and dioxin degradation rate for different examples

It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that changes and modifications to the above described embodiments are within the scope of the claims of the present invention as long as they are within the spirit and scope of the present invention.