TWI472356B - Method for quickly removing hazardous matters from mswi fly ash - Google Patents

Description

Method for quickly removing harmful substances from waste incineration fly ash

The invention relates to the technical field of treatment of harmful fly ash from waste incineration. More specifically, the harmful heavy metal and dioxin in the waste incineration fly ash can be quickly removed, so that the fly ash detection after treatment is lower than the regulatory standards. It is a method for quickly removing harmful substances from waste incineration fly ash by harmless and reusable substances.

The fly ash produced by the incineration of waste is often referred to as the municipal solid waste incineration fly ash (or MSWI fly ash). Since the incineration temperature is usually between 850-1,050 °C, the heavy metal with lower boiling point than the incineration temperature is easy to gasify. As the exhaust gas and fly ash enter the air pollution control equipment of the incineration plant, the heavy metal condenses and mostly adheres. On the fly ash. In addition, if there is chlorine-containing organic matter in the garbage, the incineration and air pollution control processes will have a precursor synthesis and a de novo synthesis reaction, forming a trace amount of dioxin, and most of them are also condensed on the fly ash. on.

According to the current regulations in China, whether the waste incineration fly ash is harmful or not, the fly ash must be tested according to the hazardous industrial waste identification standards: (1) the heavy metal concentration of the toxicity characteristic leaching procedure (TCLP), and (2) the total toxicity of dioxin Equivalent concentration (referred to as the total amount of dioxin). The EPA has regularly tested the concentration of TCLP heavy metals and the total amount of dioxin in fly ash from domestic incineration plants over the years. The test results are mostly Pb exceeding TCLP regulations (5.0 mg/L), and some are Cd over TCLP regulations (1.0 mg). /L), the remaining heavy metal dissolution values are lower than the TCLP regulations. In addition, the total dioxin value of the fly ash produced by each incineration plant was lower than the regulatory standard (1.0 ng I-TEQ/g). It can be seen from the above that under the current domestic regulations, waste incineration fly ash is a hazardous business waste due to heavy metals exceeding TCLP regulations.

At present, in some advanced countries in China and the world, the harmful fly ash is first solidified/stabilized with cement and chemical stabilizers, and then the fly ash solidified material is transported to an independent sanitary landfill for burial. However, this method can not only reuse fly ash, but also increase the volume of waste, consume limited space in the landfill, and increase the processing cost. What's more, the fly ash is solidified due to solidification of fly ash or landfill rain. Harmful substances in the material dissolve and pollute the water and soil environment. Therefore, how to no longer solidify and bury the waste incineration fly ash, and to effectively remove the harmful substances in the fly ash, so that the treated fly ash meets the non-harmful standards of the regulations (including the TCLP heavy metal dissolution and the total amount of dioxin). An important topic for reuse!

Known about the treatment of fly ash or bottom residue after incineration or high temperature treatment of waste or other substances. The invention or new patent case or publication of the Republic of China is as follows: Invention No. 301697 "Stability and Re-ash of Ashes "Inventive No. 393448 "Method for converting ash into inertia"; Invention No. 468021 "Glass melting method and ash melting furnace"; Invention No. 502099 "Method for reprocessing slag and/or ash of waste heat treatment" Section No. I278442 "Method and Apparatus for Removing Chloride Containing Bottom Ash"; No. I311494 "Method for Removal of Heavy Metals from Waste Incineration-Derived Fly Ash"; No. I314543 "Method for Producing Adsorbent Material from Coal Ash"; No. I325795 "Method for the use of dicalcium phosphate dihydrate powder to stabilize heavy metals in the bottom of incinerators and odour control"; No. I310699 "Method and apparatus for decomposing Dioxin"; No. I288028 "Incinerated bottom slag washing process"; No. I257330 "Processing method and apparatus for incineration fly ash"; No. I256377 "Sludge sand mixed fly ash treatment" Method and product thereof; No. I231234, "Processing agent and procedure for discharging dioxin-like compound in incinerator"; Inventive Publication No. 523550 "Steelmaking method for recycling waste incineration fly ash by electric arc furnace"; Invention Disclosure 201013123 No. "Handling method for harmless fly ash containing fly ash"; Patent No. M369800 "Fly ash chelating agent mixing and adding equipment" and other patent cases and publications.

Further, the waste incineration fly ash treatment technology which is similar to the present invention is disclosed. Two of them are the patented technologies of the inventors of the case, and the first one is the method of “Removal of heavy metals from waste incineration-derived fly ash” No. I311494, which is based on the original fly ash and reaction containing different heavy metal species in different places in the incineration plant. Fly ash, take the fly ash out and mix it in the opposite direction of the relative concentration ratio. Firstly, reduce the heavy metal concentration of the mixed fly ash, and then remove the heavy metal of the fly ash by 4-8 times of water and 10-24 hours of extraction. The second is the invention of the publication No. 201013123 "Treatment treatment method for heavy metal incineration fly ash", which is the first stage for the confluence fly ash produced by the incineration plant (ie, the confluent fly ash before entering the solidification plant) Extraction with clean water or weak lye (0.001-0.05 N NaOH), ie, liquid-solid (dry weight) at 2-3 and 100-250 rpm for 4-12 hours, followed by standing fly ash slurry 8- After 16 hours, the solid-liquid separation is carried out; the fly ash after the first stage extraction is subjected to the second-stage medium concentration acid solution (0.5-2.0 M H ₂ SO ₄ or HNO ₃ ) extraction, and the liquid-solid (wet weight) ratio is 1.0. Extraction at -1.5 and 100-250 rpm for 4-12 hours to remove heavy metals from fly ash.

In addition, the No. I328095 "Incinerator Fly Ash Reuse Treatment Method" is a step of stabilizing primary fly resin coating processing, granulation processing, mixing secondary resin coating processing, molding processing, and the like. Use of finished products for non-hazardous engineering. No. I257330 "Processing and Apparatus for Incineration Fly Ash" is to first remove fly ash from chlorine, solid-liquid separation, and then knead the fly ash to a cement heating kiln.

According to the above-mentioned waste incineration fly ash treatment method, most of the technologies adopt solidification/stabilization, gasification, high-temperature melting, etc., and the mechanisms thereof are: immobilization of fly ash solid phase harmful substances by immobilization and stabilization agents It is not easy to dissolve; the high-temperature fly ash solid phase harmful substances are decomposed or converted into gas phase substances and removed; in addition to high temperature, the fly ash solid phase harmful substances are decomposed or converted into gas phase substances and removed, and high temperature is used to fly fly ash. The inorganic substance is melted to enrich the fly ash, so it is not easily dissolved. The inventor of the present invention mainly adopts an extraction mechanism for the treatment of fly ash, which is to remove the harmful substances of fly ash from the solid phase to the liquid phase; as for the content outline and difference of the two cases of the present invention and the present inventors, summarized as follows :

(1) First case (No. I311494): Different mixing methods were proposed for the original fly ash and reaction fly ash of the incineration plant; thereafter, the fly ash heavy metal was removed by 4-8 times of water and 10-24 hours of extraction.

(2) The second case (Public No. 201013123): The domestic waste incineration plant is in response to the convenience of solidification treatment of fly ash. Therefore, after the fly ash is collected in the air pollution control equipment in the factory, most of it is transported by fly ash in the plant. After the pipes meet, they enter the curing equipment. This case is more in line with practicality and novelty, so it is no longer aimed at the original fly ash, reaction fly ash, but the confluence fly ash before entering the fly ash solidification treatment equipment; this case adopts the second stage type (clear water or weak lye, Removal of heavy metals from fly ash by medium-concentration acid solution, 100-250 rpm and 4-12 hours of operating conditions.

(3) This application: In order to remove the harmful substances of fly ash (including heavy metals and dioxin) more quickly and effectively, the inventors of the present invention further studied and found more practical and better techniques, and proposed the present application. The object of this case is the confluent fly ash produced by the incineration plant; the low water-solid ratio (2-5), high-speed (500-1,500 rpm), short-time (3-10 min) water extraction method can be used to verify that it can be quickly removed. Gray heavy metals and reduce the total amount of dioxin, to achieve the standard of harmless fly ash after treatment.

The main object of the present invention is to provide a method for rapidly removing harmful substances of waste incineration fly ash, which is treated by confluent fly ash (ie, confluent fly ash before entering the curing treatment equipment) produced by incineration of the waste incineration plant, which can be quickly and Effectively remove harmful substances from fly ash, and the harmless fly ash after treatment can be used as a raw material for reuse, achieving the goal of “zero waste” and “recycling resources”.

Therefore, in order to achieve the foregoing objects, the present invention provides a method for rapidly removing harmful substances from waste incineration fly ash, comprising at least the following steps: preparing fly ash and clear water: preparing for the combined fly ash produced by the waste incineration plant to be treated And preparing the required water; stirring extraction: in the low liquid-solid ratio of fresh water and fly ash, adding clear water to the fly ash, and performing stirring extraction; immersion extraction: impregnating the fly ash slurry after high-speed extraction to make fly ash The material continues to be released from the fly ash; solid-liquid separation: solid-liquid separation of the fly ash slurry after immersion extraction; drying: the fly ash still contains moisture after solid-liquid separation, so the first drying; pulverization: fly ash drying easy to knot Block, in order to facilitate subsequent reuse, it is smashed; detection: detecting the TCLP heavy metal dissolution value and the total amount of dioxin in the crushed fly ash; if passing, the crushed fly ash is harmless substance, which can be used for subsequent reuse; Pass, then return to the step of preparing fly ash.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 1, a method for rapidly removing harmful substances from waste incineration fly ash according to a preferred embodiment of the present invention mainly includes The following steps: the first step of the present invention is to prepare fly ash and clean water 100: in the case of a waste incineration plant, the fly ash is a confluent fly ash collected by the air pollution control equipment of the waste incineration plant, and the clean water can be tap water. Distilled water or water treated with soft water.

The second step of the present invention is to stir the extraction 110: adding fresh water to the fly ash, stirring the fly ash and the clean water thoroughly at a high-speed stirring manner, and crushing the fly ash for extraction. The "liquid weight: fly ash solids (dry weight) ratio" is 2-5:1, the stirring speed is 500-1,500 rpm, and the time is 3-10 min. This step mainly uses the high-speed stirring to crush the fly ash, so that the material in the fly ash can be released quickly and in large quantities, which can play a mechanism of mass mass transfer; the alkali metal and alkaline earth metal oxide in the fly ash react with water to form a large number of OH ^- ions, due to the low liquid to solid ratio, so that OH ^- ion concentration is high, most of the fly ash cause Pb, Zn and Cd amphoteric metal species portion of species with OH ^- to form a soluble species out of the liquid phase, However, other heavy metal species whose original concentration is low in fly ash tend to form a precipitate of hydroxide, which is also a chemical reaction mechanism to be utilized in the present invention.

The third step of the present invention is immersion extraction 120: the fly ash slurry after high-speed stirring extraction is allowed to stand for 10-60 min, and immersion extraction is performed. This step is mainly to continue the release and reaction of the broken fly ash material, especially this step can promote the diffusion mechanism of the slower reaction between solid and liquid.

The fourth step of the present invention is a solid-liquid separation 130: separating the fly ash from the waste liquid by dehydration of the fly ash slurry after the immersion extraction by pressure filtration, vacuum filtration or centrifugation. This step is mainly to separate the fly ash solids and waste liquid to facilitate the treatment of the fly ash solids before reuse. The other waste liquids must be treated by wastewater treatment equipment because they contain heavy metals and other pollutants.

The fifth step of the present invention is drying 140: heating and drying the fly ash after solid-liquid separation at a temperature of 100-200 ° C to remove moisture in the fly ash.

The sixth step of the present invention is pulverization 150: the fly ash after drying is pulverized by a conventional crusher, and the fly ash particle size after pulverization should be less than 1.0 mm. The fly ash is easy to agglomerate and is smashed for subsequent reuse.

The final step of the invention is the detection 160: detecting the TCLP dissolution value of the crushed fly ash and the total amount of dioxin. If passed, the crushed fly ash is a harmless substance that can be reused; if it is not passed, the step of preparing fly ash and clean water 100 is repeated.

In addition, the waste liquid after solid-liquid separation should be treated in a wastewater treatment facility because it contains heavy metals and other pollutants. As for the fly ash, Dioxin is not easily soluble in water, acid and alkali. Therefore, the present invention utilizes high-speed stirring, crushing fly ash, solid-liquid separation and the like, and the amount of dioxin in the fly ash which is lower than the regulatory standard, and how much with waste water and Very small colloids are moved into the wastewater, so the treatment of fly ash solids is also lower than the regulatory standards.

Hereinafter, the confluent fly ash of a large-scale garbage incineration plant is treated by the technology of the present invention, and the results are as follows:

It can be seen from the above that the invention utilizes cheap water as an extracting agent, fully utilizes low liquid-solid ratio and high-speed operating conditions, so that fly ash is broken and easily dissolved, and high concentration of OH ^{- is} generated, and harmful substances such as Pb are favorably moved from the solid phase to The liquid phase not only has a short processing time and low cost, but also has no harm to the fly ash after the treatment, and can be used as a raw material for recycling to achieve the purpose of "zero waste" and "recycling resources"; the reason is that the present invention is in compliance with the invention patent. The requirements, 提出 apply in accordance with the law.

100. . . Prepare fly ash and clean water

110. . . Stirring extraction

120. . . Dip extraction

130. . . Solid-liquid separation

140. . . drying

150. . . Crush

160. . . Detection

1 is a flow chart of a preferred embodiment of the present invention.

100. . . Prepare fly ash and clean water

110. . . Stirring extraction

120. . . Dip extraction

130. . . Solid-liquid separation

140. . . drying

150. . . Crush

160. . . Detection

Claims (1)

A method for rapidly removing harmful substances of waste incineration fly ash comprises at least the following steps: preparing fly ash and clear water: preparing for the combined fly ash produced by the garbage incineration plant and preparing the clean water as an extractant, and the fly ash means the air pollution of the waste incineration plant The fly ash collected by the control equipment is the fly ash that meets before the curing treatment equipment. The clean water refers to tap water, distilled water, or water treated by soft water. Stirring extraction: adding clear water to the fly ash, stirring the fly ash Stir thoroughly with water, and crush the fly ash for extraction, wherein the "water weight: fly ash solid (dry weight) ratio" is 2-5:1, the stirring speed is 500-1,500 rpm, and the time is 3-10 min; Dip extraction: After standing and stirring, the fly ash slurry is subjected to immersion extraction for 10 to 60 minutes; solid-liquid separation: dehydration of the fly ash slurry after immersion extraction, and fly ash and waste liquid by pressure filtration, vacuum filtration or centrifugation Separation; drying: the fly ash after solid-liquid separation is heated and dried at a temperature of 100-200 ° C; pulverization: drying fly ash pulverization, the fly ash particle size after pulverization is less than 1.0 mm; and detection: detecting crushed fly ash TCLP dissolution The value and the total value of the dioxin, if passed, the pulverized fly ash is the harmless substance that can be reused; if it fails, the steps of preparing the fly ash and the clean water are repeated, wherein the detection method and the passing value are environmentally friendly. Standard test methods for regulations and their regulatory values.