WO2019034011A1 - 一种垃圾焚烧飞灰稳定无害化处理的方法 - Google Patents

一种垃圾焚烧飞灰稳定无害化处理的方法 Download PDF

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WO2019034011A1
WO2019034011A1 PCT/CN2018/100151 CN2018100151W WO2019034011A1 WO 2019034011 A1 WO2019034011 A1 WO 2019034011A1 CN 2018100151 W CN2018100151 W CN 2018100151W WO 2019034011 A1 WO2019034011 A1 WO 2019034011A1
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fly ash
flue gas
sludge
incineration
water
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PCT/CN2018/100151
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English (en)
French (fr)
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李秉正
李�一
吴汕
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重庆盎瑞悦科技有限公司
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Publication of WO2019034011A1 publication Critical patent/WO2019034011A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/44—Details; Accessories
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J3/00—Removing solid residues from passages or chambers beyond the fire, e.g. from flues by soot blowers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2700/00—Ash removal, handling and treatment means; Ash and slag handling in pulverulent fuel furnaces; Ash removal means for incinerators
    • F23J2700/003—Ash removal means for incinerators

Definitions

  • the invention belongs to the technical field of hazardous and harmful solid waste treatment, and particularly relates to a method for stable and harmless treatment of waste incineration fly ash.
  • Waste incineration fly ash is mainly collected from waste incineration flue gas treatment. It contains a considerable amount of toxic substances such as dioxins and heavy metals. Once these toxic substances enter the environment, they will cause great damage to the ecology and endanger the health of residents. As a new technology developed in recent years, the melting method can effectively treat dioxins and heavy metals in fly ash, and slag can also be utilized in resources, and is “reduced, harmless, stabilized, and resourced”. Aspects have obvious advantages.
  • the conventional melt processing methods often have disadvantages such as small processing amount, complicated operation, and difficulty in implementation, and the content of heavy metals such as soluble salts, chlorine, lead, and zinc in the residue after the molten treatment is still high, so that the residue is in resources. There are significant restrictions on the use of chemicals.
  • the object of the present invention is to provide a method for stable and harmless treatment of waste incineration fly ash, wherein the fly ash residue treated by the method is completely detoxified, not only completely decomposing dioxin, but also effectively removing a large amount of soluble chlorine in the fly ash.
  • Salt and heavy metal ions such as Pb, Zn, Cr, Cu, As, etc., a small amount of residual heavy metals are also solid-dissolved in the residue, no longer have leaching toxicity, fly ash residue can be resourced for light building aggregate reuse, economical and environmentally friendly;
  • the method is environmentally friendly, economically feasible, and simple to operate.
  • the present invention provides the following technical solutions:
  • a method for stable and harmless treatment of waste incineration fly ash comprising the following steps:
  • Step 1 Mix the waste incineration fly ash with water at a solid-liquid mass ratio of 1:5-10, stir the slurry, precipitate, separate the supernatant and mud paste, and press the mud paste to obtain the filtrate and sludge.
  • pulping treatment it is possible to leach out about 20% of Na, K, Ca, about 60% of Cl and about 5% of heavy metals including Pb, Cr, Zn, Cu, Cd in the waste incineration fly ash;
  • Step 2 Mix the sludge 1 obtained in step 1 with the sulfuric acid solution at a ratio of solid to liquid of 1:3-5, control the pH to 1-2, mix and stir for 0.5 to 1 h, and press filter to obtain acidic filtrate and sludge 2. After acid leaching, it can dissolve the metal ions other than lead in the sludge 1, and the lead enters the sludge 2 in the form of lead sulfate;
  • Step 3 The sludge 2 obtained in the step 2 is mixed with quicklime, and the pH of the obtained product is controlled to be 6-7, and the obtained mixture is mixed with water at a solid-liquid mass ratio of 1:5-10, stirred for 15-20 min, and then stirred. Pressing to obtain neutral filtrate and sludge 3, controlling the water content of the sludge 3 to not exceed 50%, neutralizing the quicklime, washing with water, and further removing residual residues including Cr, Zn, Cu, and Cd in the sludge 2 Heavy metal inside; after "washing-acid leaching-washing" treatment, the total removal rate of heavy metals is 30%, the removal rate of soluble chlorine salts is 60%, and the removal rate of chloride ions is 80%;
  • Step 4 The sludge 3 obtained in the step 3 is dried to a moisture content of not more than 8%, and then sent to a ball mill or a crusher to be ground into a powder, and the wet exhaust gas produced by the drying is discharged after reaching the standard;
  • Step 5 The powder obtained in the step 4 is sent to a cylindrical pelletizer to form a small ball, and the fly ash pellet having a particle diameter of 8 to 12 mm is sieved and sent to a cylinder mixer to form fly ash with the combustion improver and water.
  • a pellet the fly ash pellet has a particle diameter of 10-14 mm, and the combustion improver is a biomass carbon powder, such as rice husk carbon, shell carbon, etc., and the amount of the oxidizer added is the mass of the fly ash pellet 8 to 10%;
  • Step 6 The fly ash pellet obtained in the step 5 is clothed in a sintering machine, and is ignited by an ignition furnace.
  • the residue after the incineration is used as a light bone material for construction, and the hot flue gas generated by the incineration is divided into two parts, and the hot flue gas 1 is used as In step 4, the heat source is dried, and the hot flue gas 2 is used as a heat source of the heat exchanger for heat exchange cooling, and finally discharged after being purified by the flue gas purification system.
  • the supernatant and the filtrate described in the step 1, the acidic filtrate described in the step 2, and the neutral filtrate described in the step 3 are subjected to reverse osmosis treatment to obtain water and a concentrate, and the obtained water is recycled.
  • the obtained concentrated liquid can be recovered by electrochemically recovering copper, reducing precipitation and recovering chromium, recovering zinc by sulfide precipitation, and recovering sodium salt by evaporation crystallization. Salt and heavy metals.
  • the mass percentage concentration of the sulfuric acid in the step 2 is 50% to 98%; preferably, the mass percentage concentration of the sulfuric acid in the step 2 is 90% to 98%.
  • the stirring slurrying time in the step 1 is not less than 30 min; preferably, the stirring slurrying time in the step 1 is 30 min.
  • the particle size of the powder in the step 4 is ⁇ 80 mesh, and such a grain-forming effect is better.
  • the fly ash pellets in the step 5 have a particle size of 8 to 12 mm, a moisture content of ⁇ 25%, a drop strength of ⁇ 5 times/piece, and a compressive strength of ⁇ 8 N/piece.
  • the fly ash pellets in the step 5 have a particle size of 10 to 14 mm, a moisture content of ⁇ 20%, a drop strength of ⁇ 8 times/piece, and a compressive strength of ⁇ 15 N/piece.
  • the fly ash ball smaller than the particle size requirement is returned to the cylindrical pelletizer to continue to grow, and the fly ash ball larger than the diameter requirement is sent to the rotary drum.
  • the dryer is reprocessed.
  • the thickness of the cloth in step 6 is 700-1200 mm. If the thickness of the layer is less than 700 mm, the temperature requirement cannot be reached, which affects the incineration effect; if the thickness of the layer is greater than 1200 mm, the gas permeability is poor and the incineration effect is not good.
  • the ignition temperature of the incineration in step 6 is 900 ° C ⁇ 50 ° C
  • the ignition time is 2 to 4 min
  • the incineration negative pressure is 1200 to 2500 Pa
  • the incineration temperature is up to 1300 ° C under this condition, which can effectively solidify and fly. Heavy metals in the ash and the complete decomposition of dioxin.
  • the purification process described in steps 4 and 6 comprises the following steps:
  • Step a the wet exhaust gas produced by the drying in step 4 and the combustion flue gas after the heat exchange cooling in step 6 are sent to the bag filter through the induced draft fan to remove the dust, and the dust removal efficiency is over 98%;
  • Step b spraying and desulfurizing the exhaust gas after the dust removal in step a, the spray liquid is sodium hydroxide solution, sodium hydroxide can form sodium sulfite with sulfur dioxide in the flue gas, and sodium sulfite can react with calcium hydroxide to form hydrogen Sodium oxide, so that sodium hydroxide can be recycled, the sulfur removal efficiency is up to 60%, and the spray liquid can also remove residual smoke;
  • Step c The desulfurization of the step b is carried out by wet denitration, and the nitrogen oxide in the flue gas is reduced to nitrogen by spraying the urea solution and controlling the pH of the solution to achieve the purpose of denitration, and the method can remove more than 80% of the flue gas.
  • the NO x The desulfurization of the step b is carried out by wet denitration, and the nitrogen oxide in the flue gas is reduced to nitrogen by spraying the urea solution and controlling the pH of the solution to achieve the purpose of denitration, and the method can remove more than 80% of the flue gas.
  • Step d the flue gas after the denitration in step c is sent to the steam separator, and the water in the flue gas in the steam separator is separated and collected for use in the cylinder making;
  • Step e passing the flue gas treated in step d through an activated carbon adsorber, removing excess heavy metals and dioxins remaining in the flue gas by adsorption of activated carbon, so that the flue gas reaches the standard;
  • Step f The purified flue gas is discharged by heat exchange with the hot flue gas 2 in step 6 through the heat exchanger, so that the purified flue gas is heated to prevent the plume phenomenon during the discharge process.
  • the inventors have found that the solid-liquid ratio of the slurry treatment in the step 1 has a great influence on the leaching effect of the chloride salt and the heavy metal ions.
  • the liquid-solid ratio is small 5
  • the leaching rate of the soluble chloride salt is less than 10%, and the leaching effect is not obvious.
  • the liquid-solid ratio is greater than 10
  • the leaching rate of soluble chlorine salt is not obvious, and the water resources are wasted, and the subsequent water recovery workload is increased.
  • the liquid-solid ratio is 5-10:1, the leaching waste can be removed to the maximum extent.
  • the soluble chlorine salt in the fly ash can reach about 60%, and at the same time, it can leach out about 20% of Na, K, Ca in waste incineration fly ash, and about 5% including Pb, Cr, Zn, Cu, Cd. Heavy metal, the leaching effect is obvious.
  • the inventors have also found that the mass ratio of the sludge 1 to the sulfuric acid solution in the step 2 has a great influence on the leaching effect, and only when the sludge 1 and the sulfuric acid solution are mixed at a ratio of solid to liquid of 1:3-5, Leaching out the metal ions in the sludge 1; when the solid-liquid mass ratio of the sludge 1 and the sulfuric acid solution is less than 1:5, the leaching effect is obviously improved, but increasing the sulfuric acid consumption is neither economical nor environmentally friendly; when the sludge When the solid-liquid mass ratio of the sulfuric acid solution is greater than 1:3, the leaching effect is greatly reduced, which affects the harmless treatment effect of the garbage fly ash.
  • the inventors have found that when the water content of the sludge 3 is controlled to not exceed 50% in the step 3, the energy consumption of the subsequent drying operation can be greatly reduced, and the subsequent operation can be simplified; in addition, the sludge 3 in the step 4 is in the drum dryer.
  • the moisture content of the drying has a great influence on the subsequent sphericity.
  • the moisture content after drying is controlled below 8%, the ball can be well formed.
  • the moisture content after drying exceeds 8%, it is not easy to form a ball.
  • the particle size of the 5 fly ash pellets directly affects the incineration effect of the fly ash. When the particle size of the fly ash pellet is 10-14 mm, the gas permeability of the layer is best when incinerated, and the sintering effect is the best.
  • Washing-acid leaching-pre-washing treatment can remove a large amount of soluble chlorine salts in the waste incineration fly ash, which have a bad influence on the production of building materials, and heavy metal ions in the exchangeable form such as carbonate-bound state, greatly reducing The content of heavy metals in waste incineration fly ash;
  • the supernatant and filtrate of the water washing and acid leaching treatment can be recycled after reverse osmosis treatment, and the water obtained by the reverse osmosis treatment can be recycled for the water washing step, and the concentrated liquid obtained by the reverse osmosis treatment can recover the copper step by step.
  • Valuable metals and salts such as chromium and zinc not only achieve zero wastewater discharge, but also recover valuable metals and improve the economic value of waste fly ash treatment;
  • the incineration residue obtained by incineration treatment has extremely low residual amounts of sodium, potassium, calcium salts, chloride ions and heavy metals, which can significantly increase the resource utilization of incineration residues, such as building lightweight bone materials;
  • the method of the invention can also effectively treat various solid wastes such as copper, chromium, nickel and lead metals, such as electroplating sludge and chromium slag, and has high applicability;
  • the method of the invention can effectively utilize waste heat of flue gas, and the energy utilization efficiency is high;
  • the method of the invention is environmentally friendly, simple in process and easy to operate.
  • a method for stable and harmless treatment of waste incineration fly ash comprising the following steps:
  • Acid leaching take a certain amount of 98% concentrated sulfuric acid, prepare it into a sulfuric acid solution with a concentration of 0.1M, mix the filter residue 1 with the sulfuric acid solution at a liquid-solid mass ratio of 3:1, and control the pH of the mixed solution to 1-2. , stirring for 45 min, and then filtering to obtain an acid leach solution and acid leach residue;
  • the filter residue 2 is placed in a drum dryer and dried at 110 ° C for 2 h until the moisture content of the filter residue falls below 8%;
  • Pelletizing The sieved material obtained by sieving is made into a ball by a cylindrical pelletizer, and the uniform particle size is obtained by controlling the rotation speed of the cylinder and the amount of water added, and then the particle size is 8 ⁇ by using a stainless steel sieve. 12mm fly ash ball, smaller than the particle size less than 8mm, return to the ball pelletizer to continue to form a ball, more than 12mm after drying and then finely treated;
  • Incineration The sieved fly ash pellets are added into a 200 mm diameter sintering furnace with a thickness of 700 mm.
  • the liquefied gas is used as the fuel for the liquefied gas.
  • the ignition temperature is 900 ° C
  • the ignition time is 2 min
  • the negative pressure is 2000 Pa
  • the incineration is performed after 60 min. Basically completed, the negative pressure will be cooled to 1200Pa, and the cooled residue will be sampled and analyzed.
  • the flue gas generated during the incineration process will also be sampled and analyzed, and the incineration temperature and the flue gas temperature will be simultaneously detected during the incineration process;
  • Flue gas purification the exhaust gas is sprayed and desulfurized, and the spray liquid is sodium hydroxide solution; after desulfurization, the exhaust gas is subjected to wet denitration, and the nitrogen oxides in the flue gas are reduced by spraying the urea solution and controlling the pH of the solution.
  • Nitrogen is used for the purpose of denitration; the flue gas after denitration is sent to the activated carbon adsorber, and the heavy metals and dioxins that may remain in the flue gas are removed by activated carbon adsorption, so that the flue gas reaches the standard; during the small test, because of the flue gas The emission is too small, only three processes of wet desulfurization, wet denitrification and activated carbon adsorption are carried out, and the flue gas is sampled and analyzed after purification treatment.

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Abstract

一种垃圾焚烧飞灰稳定无害化处理的方法，所述方法处理的飞灰残渣解毒彻底，不仅将二噁英彻底分解，同时能够有效去除飞灰中的大量可溶性氯盐以及Pb、Zn、Cr、Cu、As等重金属离子，极少量残余重金属也固溶于残渣中，不再具有浸出毒性，飞灰残渣能够资源化做建筑轻骨料再利用，经济环保；此外，所述方法环境友好、经济可行、操作简单。

Description

一种垃圾焚烧飞灰稳定无害化处理的方法 技术领域
本发明属于危险有害固废处理技术领域，具体涉及一种垃圾焚烧飞灰稳定无害化处理的方法。
背景技术
垃圾焚烧飞灰主要是垃圾焚烧烟气处理中收集到的颗粒物，其含有相当数量二噁英、重金属等毒性物质，这些有毒物质一旦进入环境将对生态造成极大破坏，危害居民健康。熔融法作为近年来所发展的新技术，可对飞灰中的二噁英、重金属进行有效处理，熔渣还可资源化利用，在“减量化、无害化、稳定化、资源化”方面具有明显优势。但是，现有的熔融处理方法多存在处理量小，操作复杂，实施困难等缺点，而且熔融处理后的残渣中因可溶性盐、氯以及铅、锌等重金属的含量仍然较高，使得残渣在资源化利用方面受到很大限制。
因此，开发研究一种既能彻底有效无害化处理垃圾焚烧飞灰、又经济可行、操作简单的方法，具有重要的意义和市场前景。
发明内容
本发明的目的是提供一种垃圾焚烧飞灰稳定无害化处理的方法，所述方法处理的飞灰残渣解毒彻底，不仅将二噁英彻底分解，同时能够有效去除飞灰中的大量可溶性氯盐以及Pb、Zn、Cr、Cu、As等重金属离子，极少量残余重金属也固溶于残渣中，不再具有浸出毒性，飞灰残渣能够资源化做建筑轻骨料再利用，经济环保；此外，所述方法环境友好、经济可行、操作简单。
为实现上述发明目的，本发明提供以下技术方案：
一种垃圾焚烧飞灰稳定无害化处理的方法，包括以下步骤：
步骤1：将垃圾焚烧飞灰与水按固液质量比1:5-10的比例混合，搅拌浆化，沉淀，分离得到上清液和泥膏，将泥膏压滤得到滤液和泥渣1，通过浆化处理，能够浸出除去垃圾焚烧飞灰中约20％的Na、K、Ca，约60％的Cl和约5％的包括Pb、Cr、Zn、Cu、Cd在内的重金属；
步骤2：将步骤1所得泥渣1与硫酸溶液按固液质量比1:3-5的比例混合，控制pH为1～2，混合搅拌0.5～1h，压滤得到酸性滤液和泥渣2，经过酸浸处理，能够溶解泥渣1中除铅以外的其它金属离子，铅以硫酸铅的形式进入泥渣2中；
步骤3：将步骤2所得泥渣2与生石灰混合，混合后所得物的pH控制为6～7，所得混合物与水按固液质量比1:5-10的进行混合，搅拌15～20min，再压滤得到中性滤液和泥渣3， 控制所述泥渣3的含水量不超过50％，生石灰中和、水洗处理，能够进一步除去泥渣2中残留的包括Cr、Zn、Cu、Cd在内的重金属；经过“水洗-酸浸-水洗”处理后，重金属总去除率达30％，可溶性氯盐去除率达60％，其中氯离子的去除率达80％；
步骤4：将步骤3所得泥渣3干燥至含水率不超过8％，再送至球磨机或破碎机中磨成粉末，干燥产生的湿废气净化处理达标后排放；
步骤5：将步骤4所得粉末送至圆筒造球机制成小球，筛取粒径为8～12mm的飞灰小球送入圆筒混料机中，与助燃剂和水制成飞灰球团，所述飞灰球团的粒径为10-14mm，所述助燃剂为生物质碳粉，如稻壳碳、果壳碳等，所述助燃剂的添加量为飞灰小球质量的8～10％；
步骤6：将步骤5所得飞灰球团布料于烧结机中，采用点火炉进行点火，焚烧完成后的残渣作为建筑轻骨材料使用，焚烧产生的热烟气分成两部分，热烟气1作为步骤4干燥的热源，热烟气2作为换热器的热源进行换热冷却，最后经烟气净化系统净化处理达标后排放。
根据本发明的方法，步骤1中所述的上清液和滤液、步骤2中所述的酸性滤液和步骤3中所述的中性滤液进行反渗透处理得到水和浓缩液，所得的水循环用于步骤1的垃圾焚烧飞灰浆化处理和/或步骤3的水洗处理，所得的浓缩液可通过电化学回收铜、还原沉淀回收铬、硫化沉淀回收锌及蒸发结晶回收钠盐等方法回收利用其中盐和重金属。
根据本发明的方法，步骤2中所述硫酸的质量百分浓度为50％-98％；优选地，步骤2中所述硫酸的质量百分浓度为90％-98％。
根据本发明的方法，步骤1中搅拌浆化的时间不低于30min；优选地，步骤1中搅拌浆化的时间为30min。
根据本发明的方法，步骤4中的粉末粒径≤80目，这样的粒级成球效果更好。
根据本发明的方法，步骤5中所述的飞灰小球粒径为8～12mm、水分≤25％、落下强度≥5次/个、抗压强度≥8N/个。
根据本发明的方法，步骤5中所述的飞灰球团粒径为10～14mm、水分≤20％、落下强度≥8次/个、抗压强度≥15N/个。
根据本发明的方法，步骤5中筛取直径为8～12mm小球后，小于粒径要求的飞灰球返回圆筒造球机中继续长大，大于直径要求的飞灰球送至转筒干燥机进行再处理。
根据本发明的方法，步骤6中的布料厚度为700～1200mm，如果料层厚度小于700mm，则无法达到温度要求，影响焚烧效果；如果料层厚度大于1200mm，则透气性差，焚烧效果不好。
根据本发明的方法，步骤6中焚烧的点火温度900℃±50℃，点火时间2～4min，焚烧负 压为1200～2500Pa，在此条件下焚烧温度最高可达1300℃，可有效固熔飞灰中的重金属以及使二噁英彻底分解。
根据本发明的方法，步骤4和步骤6中所述的净化处理包括以下步骤：
步骤a：将步骤4干燥产生的湿废气和步骤6换热冷却后的燃烧烟气通过引风机送至袋式除尘器中除去烟尘，除尘效率98％以上；
步骤b：将步骤a除尘后的废气进行喷淋除硫，喷淋液为氢氧化钠溶液，氢氧化钠能够与烟气中的二氧化硫形成亚硫酸钠，而亚硫酸钠可通过与氢氧化钙反应再生成氢氧化钠，从而可实现氢氧化钠得循环再生，除硫效率达60％，同时喷淋液还可以除去残留的烟尘；
步骤c：将步骤b脱硫后废气进行湿法脱硝，通过喷淋尿素溶液并控制溶液PH将烟气中的氮氧化物还原成氮气，实现脱硝的目的，该法可除去烟气中80％以上的NO x；
步骤d：将步骤c脱硝后的烟气送入汽水分离器中，在汽水分离器中烟气中的水被分离出来经收集后可用于圆筒造球；
步骤e：将步骤d处理后的烟气通过活性炭吸附器，通过活性炭吸附除去烟气可能残留的重金属以及二噁英，使烟气达标；
步骤f：净化后的烟气通过换热器与步骤6中的热烟气2进行热交换后排放，使得净化后的烟气被加热，防止排放过程中出现烟羽现象。
本发明人发现，步骤1中浆化处理的固液比对氯盐以及重金属离子的浸出效果影响很大，当液固比小5时，可溶性氯盐浸出率不到10％，浸出效果不明显；当液固比大于10时，可溶性氯盐浸出率增加不明显，且浪费水资源，增加后续水回收工作量；当液固比为5-10:1时，能够最大程度地浸出除去垃圾焚烧飞灰中的可溶性氯盐，约能达到60％，同时能浸出除去垃圾焚烧飞灰中约20％的Na、K、Ca，约5％的包括Pb、Cr、Zn、Cu、Cd在内的重金属，浸出效果明显。
本发明人还发现，步骤2中泥渣1与硫酸溶液的质量比对浸出效果影响很大，只有当泥渣1与硫酸溶液按固液质量比1:3-5的比例混合时，才能充分浸出泥渣1中的金属离子；当泥渣1与硫酸溶液的固液质量比小于1:5时，浸出效果物明显改善，但增加硫酸耗量，既不经济，也不环保；当泥渣1与硫酸溶液的固液质量比大于1:3时，浸出效果大大降低，影响垃圾飞灰的无害化处理效果。
本发明人发现，步骤3中当控制泥渣3的含水量不超过50％时，可以大大减少后续干燥操作的能耗，简化后续操作；此外，步骤4中泥渣3在转筒干燥机中干燥的含水率对后续成球率影响较大，当干燥后的含水率控制在8％以下时，可以很好地成球；当干燥后的含水率 超过8％时，不易后续成球；步骤5中飞灰球团的粒径直接影响垃圾飞灰的焚烧效果，当飞灰球团的粒径为10-14mm时，焚烧时料层透气性最佳，烧结效果最好。
本发明方法具有以下优势：
1、采用水洗-酸浸-水洗前处理，能够去除垃圾焚烧飞灰中大量的、对建筑材料生产影响极坏的可溶性氯盐、以碳酸盐结合态等可交换形态存在重金属离子，大大降低了垃圾焚烧飞灰中重金属的含量；
2、水洗、酸浸处理的上清液、滤液能够经过反渗透处理后循环利用，反渗透处理得到的水能够循环用于水洗步骤，反渗透处理得到的浓缩液能够分步有效地回收铜、铬、锌等有价金属及盐，不仅实现零废水排放，且能够回收有价金属，提高垃圾飞灰处理的经济价值；
3、通过制备成10～14mm的飞灰球团，能够增加物料传热面积和料层透气性，提高熔融效率；
4、焚烧处理得到的焚烧残渣，钠、钾、钙盐、氯离子及重金属残留量极低，能够显著增加焚烧残渣的资源化利用用途，如作建筑轻骨材料；
5、本发明方法还能够对各种含铜铬镍铅等金属的固体废物，如电镀污泥、铬渣进行有效处理，适用性强；
6、本发明方法能够有效利用烟气余热，能源利用效率高；
7、本发明方法环境友好、流程简单、易操作。
具体实施例
实施例1焚烧垃圾飞灰的处理
一种垃圾焚烧飞灰稳定无害化处理的方法，包括以下步骤：
1)水洗：称取某垃圾发电厂垃圾焚烧飞灰50kg与蒸馏水500kg按液固质量比10:1进行混合浆化，充分搅拌30min，再进行静置沉淀；抽离上清液，将下层泥膏过滤得到滤液1和滤渣1，将上清液与滤液1混合后取样分析；
2)酸浸：取一定量的98％浓硫酸，将其配制成浓度0.1M的硫酸溶液，将滤渣1与硫酸溶液按液固质量比3:1进行混合，控制混合液PH为1～2，搅拌45min，再进行过滤得到酸浸出液和酸浸渣；
3)水洗：先将酸浸渣与生石灰进行混合以中和渣中硫酸，再将中和后的渣与蒸馏水按液固质量比5:1进行混合浆化，搅拌15min后压滤得到滤液2和滤渣2，将滤液2与上述酸浸出液、上清液及滤液1混合后取样分析其中的可溶性氯盐及重金属Pb、Cr、Zn、Cu等的含量；
4)烘干：将滤渣2放入转筒干燥机中，在110℃条件下烘干2h，直至滤渣的含水率降至8％以下；
5)磨粉：将烘干后飞灰渣送入球磨机中进行磨细，磨成的粉末用80目的筛网筛分；
6)造球：将筛分得到的筛下物用圆筒造球机进行制球，通过控制圆筒转速及添加水量制取粒径均匀小球，再用不锈钢筛网筛选出粒径为8～12mm的飞灰小球，小于粒径小于8mm返回圆筒造球机继续成球，大于12mm的烘干后再磨细处理；
7)覆裹：将粒径8～12mm的飞灰小球加入圆筒混料机中，按小球的加入量称取其重量10％的稻壳碳粉添加到圆筒混料机中进行覆裹制取飞灰球团，再用筛网筛取出粒径10～14mm的球团；
8)焚烧：将筛取的飞灰球团加入直径200mm的烧结炉中，料层厚度700mm，以液化气作为点化燃料，点火温度900℃，点火时间2min，焚烧负压2000Pa，60min后焚烧基本完成，将负压将至1200Pa进行冷却，对冷却后的残渣取样分析，同样对焚烧过程产生的烟气取样分析，焚烧过程中同时检测记录焚烧温度、烟气温度；
9)烟气净化：将废气进行喷淋除硫，喷淋液为氢氧化钠溶液；脱硫后废气进行湿法脱硝，通过喷淋尿素溶液并控制溶液PH将烟气中的氮氧化物还原成氮气，实现脱硝的目的；再将脱硝后的烟气送入通过活性炭吸附器，通过活性炭吸附除去烟气可能残留的重金属以及二噁英，使烟气达标；小试过程中，因为烟气的排放量太小，只进行了湿法脱硫、湿法脱硝及活性炭吸附三个工序，烟气经净化处理后取样分析。
以下是部分分析结果：
a、垃圾焚烧飞灰成分分析
Figure PCTCN2018100151-appb-000001
b、垃圾焚烧飞灰重金属分析
Figure PCTCN2018100151-appb-000002
c、残渣浸出毒性分析
Figure PCTCN2018100151-appb-000003
Figure PCTCN2018100151-appb-000004
d、净化前后的烟气成分分析
Figure PCTCN2018100151-appb-000005
经过“水洗-酸浸-水洗”的前处理后，原飞灰中的可溶性氯盐(NaCl、KCl)约59％被浸洗掉，其中Cl的去除率约77％，重金属Pb、Cr、Zn、Cd、Cu的去除率约72％。焚烧烟气经处理后完全可达标排放，残渣完全可以资源化综合利用。

Claims (10)

  1. 一种垃圾焚烧飞灰稳定无害化处理的方法，包括以下步骤：
    步骤1：将垃圾焚烧飞灰与水按固液质量比1:5-10的比例混合，搅拌浆化，沉淀，分离得到上清液和泥膏，将泥膏压滤得到滤液和泥渣1；
    步骤2：将步骤1所得泥渣1与硫酸溶液按固液质量比1:3-5的比例混合，控制pH为1～2，混合搅拌0.5～1h，压滤得到酸性滤液和泥渣2；
    步骤3：将步骤2所得泥渣2与生石灰混合，混合后所得物的pH控制为6～7，所得混合物与水按固液质量比1:5-10的进行混合，搅拌15～20min，再压滤得到中性滤液和泥渣3，控制所述泥渣3的含水量不超过50％；
    步骤4：将步骤3所得泥渣3干燥至含水率不超过8％，再送至球磨机或破碎机中磨成粉末，干燥产生的湿废气净化处理达标后排放；
    步骤5：将步骤4所得粉末送至圆筒造球机制成小球，筛取粒径为8～12mm的飞灰小球送入圆筒混料机中，与助燃剂和水制成飞灰球团，所述飞灰球团的粒径为10-14mm，所述助燃剂为生物质碳粉，所述助燃剂的添加量为飞灰小球质量的8～10％；
    步骤6：将步骤5所得飞灰球团布料于烧结机中，采用点火炉进行点火，焚烧完成后的残渣作为建筑轻骨材料使用，焚烧产生的热烟气分成两部分，热烟气1作为步骤4干燥的热源，热烟气2作为换热器的热源进行换热冷却，最后经烟气净化系统净化处理达标后排放。
  2. 如权利要求1所述的方法，其特征在于：步骤1中所述的上清液和滤液、步骤2中所述的酸性滤液和步骤3中所述的中性滤液进行反渗透处理得到水和浓缩液，所得的水循环用于步骤1的垃圾焚烧飞灰浆化处理和/或步骤3的水洗处理，所得的浓缩液可通过电化学回收铜、还原沉淀回收铬、硫化沉淀回收锌及蒸发结晶回收钠盐等方法回收利用其中盐和重金属。
  3. 如权利要求1所述的方法，其特征在于：步骤2中所述硫酸的质量百分浓度为50％-98％；优选地，步骤2中所述硫酸的质量百分浓度为90％-98％。
  4. 如权利要求1所述的方法，其特征在于：步骤1中搅拌浆化的时间不低于30min；优选地，步骤1中搅拌浆化的时间为30min。
  5. 如权利要求1所述的方法，其特征在于：步骤4中的粉末粒径≤80目。
  6. 如权利要求1所述的方法，其特征在于：步骤5中所述的飞灰小球粒径为8～12mm、水分≤25％、落下强度≥5次/个、抗压强度≥8N/个；步骤5中所述的飞灰球团粒径为10～14mm、水分≤20％、落下强度≥8次/个、抗压强度≥15N/个。
  7. 如权利要求1所述的方法，其特征在于：步骤5中筛取直径为8～12mm小球后，小于粒径要求的飞灰球返回圆筒造球机中继续长大，大于直径要求的飞灰球送至转筒干燥机进行再处理。
  8. 如权利要求1所述的方法，其特征在于：步骤5中所述的助燃剂选自稻壳碳和果壳碳。
  9. 如权利要求1所述的方法，其特征在于：步骤6中的布料厚度为700～1200mm，焚烧的点火温度900℃±50℃，点火时间2～4min，焚烧负压为1200～2500Pa。
  10. 如权利要求1所述的方法，其特征在于：步骤4和步骤6中所述的净化处理包括以下步骤：
    步骤a：将步骤4干燥产生的湿废气和步骤6换热冷却后的燃烧烟气通过引风机送至袋式除尘器中除去烟尘，除尘效率98％以上；
    步骤b：将步骤a除尘后的废气进行喷淋除硫，喷淋液为氢氧化钠溶液，氢氧化钠能够与烟气中的二氧化硫形成亚硫酸钠，而亚硫酸钠可通过与氢氧化钙反应再生成氢氧化钠，从而可实现氢氧化钠得循环再生，除硫效率达60％，同时喷淋液还可以除去残留的烟尘；
    步骤c：将步骤b脱硫后废气进行湿法脱硝，通过喷淋尿素溶液并控制溶液PH将烟气中的氮氧化物还原成氮气，实现脱硝的目的，该法可除去烟气中80％以上的NO x；
    步骤d：将步骤c脱硝后的烟气送入汽水分离器中，在汽水分离器中烟气中的水被分离出来经收集后可用于圆筒造球；
    步骤e：将步骤d处理后的烟气通过活性炭吸附器，通过活性炭吸附除去烟气可能残留的重金属以及二噁英，使烟气达标；
    步骤f：净化后的烟气通过换热器与步骤6中的热烟气2进行热交换后排放，使得净化后的烟气被加热，防止排放过程中出现烟羽现象。
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CN106282585A (zh) * 2016-09-27 2017-01-04 中国科学院城市环境研究所 一种生活垃圾焚烧飞灰的脱毒分级资源化利用方法
CN106734099A (zh) * 2016-12-27 2017-05-31 重庆盎瑞悦科技有限公司 采用二次物料复合技术高温无害化处置垃圾焚烧飞灰的方法
CN107013924A (zh) * 2017-04-20 2017-08-04 福建广汇龙环保科技研究院有限公司 垃圾焚烧飞灰处理设备及处理方法
CN107477597A (zh) * 2017-08-15 2017-12-15 重庆盎瑞悦科技有限公司 一种垃圾焚烧飞灰稳定无害化处理的方法

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