Detoxification and resource utilization system and method for waste incineration fly ash

Abstract

The invention discloses a waste incineration fly ash detoxification and resource utilization system and method, the system comprises a washing reduction system, a water treatment salt separation system, a pyrolysis drying system and a fly ash resource utilization system, the washing reduction system adopts a pre-washing + pickling + washing + flotation process, and is used for regulating and controlling chemical composition and heavy metal leaching toxicity of detoxified fly ash; the water treatment salt separation system comprises pH adjustment, decalcification, heavy metal removal, membrane treatment, evaporation salt separation and is used for purification of washing fly ash and salt recovery, the pyrolysis drying system comprises pyrolysis drying and grinding and is used for decomposing dioxin and regulating and controlling the physical state of detoxified fly ash, and the fly ash recycling system adopts the idea of concrete blending. The detoxified fly ash is used as a mixture, and resource utilization is realized in a concrete form. The system and the method are controllable in disposal process and consumption path risk, low in carbon, green, low in energy consumption and suitable for disposal and utilization of urban fly ash of different scales, and the problem that detoxification fly ash is difficult to consume is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of waste incineration disposal, and specifically relates to a fly ash detoxification and resource utilization system and method. Background Art

[0002] Waste incineration fly ash is produced during the flue gas treatment process of waste incineration. Because fly ash is enriched with highly toxic pollutants such as heavy metals and dioxins in the incineration flue gas and has leaching toxicity, it is included in the "National List of Hazardous Wastes". According to the "Technical Specifications for Pollution Control of Fly Ash from Municipal Waste Incineration (Trial)" (HJ 1134-2020), the detoxification of three types of harmful factors, soluble chlorine, heavy metals, and dioxins, must be completed before fly ash is utilized as a resource. Based on the comprehensive disposal cost considerations, "low-temperature pyrolysis + water washing" is the current mainstream fly ash disposal route, and there have been many implementation cases. Comparing existing cases, it can be seen that the stable operation of the above-mentioned disposal routes depends on the end-use method of detoxified fly ash. The common idea is to prepare detoxified fly ash as recycled building materials, but there is actually a problem of low market acceptance of hazardous waste recycling products, especially in cities where the sources of recycled building materials are extensive, which seriously affects the consumption of detoxified fly ash.

[0003] As the fundamental material of infrastructure, the average weekly output of concrete in China reached 2.082 million cubic meters in 2023. It has the characteristics of large output, multiple grades, wide application range, and high adaptability to coordinated disposal. It can be used as the main path for resource utilization of urban detoxification fly ash. A large number of studies have shown that fly ash mixed with concrete has a certain solidification effect on heavy metals in fly ash, indicating that fly ash mixed with concrete has technical feasibility. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a fly ash detoxification and resource utilization system and method to solve the deficiencies in the prior art.

[0005] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0006] On the one hand, a waste incineration fly ash detoxification and resource utilization system is provided, which includes a water washing and reduction system, a water treatment and salt separation system, a pyrolysis and drying system and a fly ash resource utilization system, the water washing and reduction system is respectively connected to the water treatment and salt separation system and the pyrolysis and drying system, the pyrolysis and drying system is connected to the fly ash resource utilization system, the water washing and reduction system regulates the chemical composition of the detoxified fly ash and the toxicity of heavy metal leaching through pre-water washing, acid washing, water washing and flotation processes, the water treatment and salt separation system includes pH adjustment, decalcification, heavy metal removal, membrane treatment and evaporation and salt separation, which are used for purification of water-washed fly ash and salt recovery, the pyrolysis and drying system includes pyrolysis and drying and grinding, which are used for decomposing dioxins and regulating the physical state of the detoxified fly ash, and the fly ash resource utilization system realizes the end utilization of fly ash through concrete admixture.

[0007] As described in the method for detoxification and resource utilization of waste incineration fly ash, in which, in the water washing and reduction system, the amount of hydrochloric acid added in the pickling process is related to the calcium sulfate content in the fly ash. The higher the calcium sulfate content, the less hydrochloric acid is used.

[0008] As described in the method for detoxification and resource utilization of waste incineration fly ash, in which, in the water washing and reduction system, a water washing process is arranged after the acid washing process, the number of water washings is not less than two times, and the water-ash ratio is greater than 2:1.

[0009] As described in the method for detoxification and resource utilization of waste incineration fly ash, in the water washing and reduction system, a flotation process is provided before the last stage of water washing and dehydration.

[0010] As described in the method for detoxification and resource utilization of waste incineration fly ash, wherein in the pyrolysis and drying system, a pulverizer is provided after pyrolysis and drying to increase the fineness of the fly ash.

[0011] As described in the waste incineration fly ash detoxification and resource utilization method, wherein in the fly ash resource utilization system, detoxified fly ash is used to replace part of the fly ash, and the doping amount is about 10-50% of the fly ash doping amount.

[0012] On the other hand, a method for detoxification and resource utilization of waste incineration fly ash is provided, wherein the method is implemented by using any one of the waste incineration fly ash detoxification and resource utilization systems, and comprises the following steps:

[0013] S1. Use the wastewater dehydrated by the washing process in proportion, supplement part of the tap water or evaporation condensate water to wash the fly ash. The liquid phase after dehydration is mainly the washing wastewater of sodium chloride and potassium chloride, and the solid phase is used for further acid washing;

[0014] S2. The pickling process uses hydrochloric acid for washing, and tap water or evaporated condensed water is added in proportion. Hydrochloric acid is slowly added dropwise. After sufficient mixing, the dehydrated liquid phase is pickling wastewater mainly composed of calcium chloride, and the solid phase is used for further water washing;

[0015] S3, the water washing process adopts two-stage or three-stage water washing, supplements tap water or evaporated condensed water in proportion, and dehydrates after sufficient stirring;

[0016] S4. Before the secondary or tertiary water washing and dehydration, a flotation process is used to add flotation agents and modifiers to separate and remove the activated carbon in the fly ash. The scum is suspended on the water surface and outsourced for treatment after separation. The remaining slurry is further dehydrated. The dehydrated liquid phase is used as pre-washing water, and the solid phase is used for further pyrolysis and drying;

[0017] S5. Set the pyrolysis temperature and time, perform pyrolysis treatment on the fly ash after water washing and reduction, decompose dioxins in the fly ash and dry the fly ash, and treat the dry flue gas to meet the emission standards. The dust generated during the flue gas treatment process is collected and returned to the pyrolysis furnace, and the solid phase after pyrolysis and drying is further ground;

[0018] S6. Use a pulverizer to further grind the fly ash to increase the fineness of the fly ash and reduce the agglomerates formed after the pyrolysis and drying process of the fly ash. The ground fly ash is detoxified fly ash for further resource utilization;

[0019] S7. Add detoxified fly ash and other mixing materials in proportion, mix thoroughly, and then sell and apply in the form of green concrete.

[0020] The beneficial effects of the technical solution of the present invention are:

[0021] On the basis of existing research and application, by combining the fly ash detoxification process and the performance requirements of concrete mixture, the process is optimized to achieve the harmless disposal and stable utilization of incineration fly ash in cities. The disposal process and disposal path have controllable risks, are low-carbon, green, and have low energy consumption. They are suitable for the disposal and utilization of fly ash in cities of different sizes, and solve the problem of the difficulty in disposing of detoxified fly ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To further illustrate the above-mentioned objectives, structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Figure 1 A schematic diagram of a system and method flow chart of a preferred embodiment of the present invention;

[0024] In the figure: 1. Water washing and reduction system; 2. Water treatment and salt separation system; 3. Pyrolysis and drying system; 4. Fly ash resource utilization system. DETAILED DESCRIPTION

[0025] The terms "invention", "present invention" and "the present invention" used in this specification are intended to refer broadly to all subject matter of this specification and any patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of any patent claim below. In addition, this specification does not attempt to describe or limit the subject matter covered by any claim of any specific component, paragraph, statement or figure of this application. The subject matter should be understood with reference to the entire specification, all drawings and any claims below. The present invention may have other embodiments and be practiced or implemented in other ways. Moreover, it should be understood that the words and terms used herein are for illustrative purposes and should not be considered as limiting.

[0026] The details of the present invention will now be discussed with reference to the accompanying drawings which illustrate the present invention by way of example only. In the accompanying drawings, similar features or components may be marked with the same reference numerals.

[0027] The use of "including," "having," and "comprising" and variations thereof herein is meant to encompass the items listed thereafter and their equivalents and additional items. Although reference may be made to directions such as above, below, upward, downward, rearward, bottom, top, front, rear, etc., in describing the drawings, for convenience, reference is made relative to the drawings. These directions are not intended to literally accept or limit the present invention in any form. In addition, terms such as "first," "second," "third," etc., are used herein for illustrative purposes and are not intended to indicate or imply importance or significance.

[0028] See also Figure 1 As shown, in a preferred embodiment, the waste incineration fly ash detoxification and resource utilization system of the present invention includes a water washing and reduction system 1, a water treatment and salt separation system 2, a pyrolysis and drying system 3 and a fly ash resource utilization system 4, the water washing and reduction system 1 is respectively connected to the water treatment and salt separation system 2 and the pyrolysis and drying system 3, the pyrolysis and drying system 3 is connected to the fly ash resource utilization system 4, the water washing and reduction system 1 regulates the chemical composition of the detoxified fly ash and the toxicity of heavy metal leaching through pre-water washing, acid washing, water washing and flotation processes, the water treatment and salt separation system 2 includes pH adjustment, decalcification, heavy metal removal, membrane treatment and evaporation and salt separation, which are used for the purification of water-washed fly ash and salt recovery, the pyrolysis and drying system 3 includes pyrolysis and drying and grinding, which are used for decomposing dioxins and regulating the physical state of the detoxified fly ash, and the fly ash resource utilization system 4 realizes the end utilization of fly ash through concrete admixture.

[0029] In the water washing and reduction system 1, the amount of hydrochloric acid added in the pickling process is related to the calcium sulfate content in the fly ash. The higher the calcium sulfate content, the less hydrochloric acid is used.

[0030] In the water washing and weight reduction system 1, a water washing process is arranged after the pickling process, the number of water washings is not less than two times, and the water-cement ratio is greater than 2:1.

[0031] In the water washing and weight reduction system 1, a flotation process is provided before the last stage of water washing and dehydration.

[0032] In the pyrolysis drying system 3, a pulverizer is provided after pyrolysis drying to increase the fineness of the fly ash.

[0033] In the fly ash resource utilization system 4, detoxified fly ash is used to replace part of the fly ash, and the doping amount is about 10 to 50% of the fly ash doping amount.

[0034] The present invention also relates to a method for detoxifying and recycling fly ash from waste incineration, which is implemented by using a system for detoxifying and recycling fly ash from waste incineration as described in any one of the above, and comprises the following steps:

[0035] S1. Use the wastewater dehydrated by the washing process in proportion, supplement part of the tap water or evaporation condensate water to wash the fly ash. The liquid phase after dehydration is mainly the washing wastewater of sodium chloride and potassium chloride, and the solid phase is used for further acid washing;

[0036] S2. The pickling process uses hydrochloric acid for washing, and tap water or evaporated condensed water is added in proportion. Hydrochloric acid is slowly added dropwise. After sufficient mixing, the dehydrated liquid phase is pickling wastewater mainly composed of calcium chloride, and the solid phase is used for further water washing;

[0037] S3, the water washing process adopts two-stage or three-stage water washing, supplements tap water or evaporated condensed water in proportion, and dehydrates after sufficient stirring;

[0038] S4. Before the secondary or tertiary water washing and dehydration, a flotation process is used to add flotation agents and modifiers to separate and remove the activated carbon in the fly ash. The scum is suspended on the water surface and outsourced for treatment after separation. The remaining slurry is further dehydrated. The dehydrated liquid phase is used as pre-washing water, and the solid phase is used for further pyrolysis and drying;

[0039] S5. Set the pyrolysis temperature and time, perform pyrolysis treatment on the fly ash after water washing and reduction, decompose dioxins in the fly ash and dry the fly ash, and treat the dry flue gas to meet the emission standards. The dust generated during the flue gas treatment process is collected and returned to the pyrolysis furnace, and the solid phase after pyrolysis and drying is further ground;

[0040] S6. Use a pulverizer to further grind the fly ash to increase the fineness of the fly ash and reduce the agglomerates formed after the pyrolysis and drying process of the fly ash. The ground fly ash is detoxified fly ash for further resource utilization;

[0041] S7. Add detoxified fly ash and other mixing materials in proportion, mix thoroughly, and then sell and apply in the form of green concrete.

[0042] As shown in Table 1 and Table 2, in a preferred embodiment, after treatment, the environmental safety indicators related to the detoxified fly ash meet HJ 1134-2020, and the detoxified fly ash is used to replace 20% of the fly ash, and the performance of the concrete mixture basically meets the requirements.

[0043]

[0044] Table 1 Key index changes in this example

[0045] Table 2 Changes in the main indicators of the detoxified fly ash product of this embodiment

[0046]

[0047] The present invention is suitable for the disposal of fly ash from incineration in cities. The risks of the disposal process, resource utilization and long-term application are controllable, and the whole process supervision of the generation end-disposal end-utilization end-long-term application can be realized, which meets the environmental safety needs of the competent authorities, disposal units and the public for hazardous waste disposal and resource utilization.

[0048] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A waste incineration fly ash detoxification and resource utilization system, characterized in that: It includes a water washing and reduction system, a water treatment and salt separation system, a pyrolysis and drying system and a fly ash resource system. The water washing and reduction system is respectively connected to the water treatment and salt separation system and the pyrolysis and drying system, and the pyrolysis and drying system is connected to the fly ash resource system. The water washing and reduction system regulates the chemical composition of the detoxified fly ash and the toxicity of heavy metal leaching through pre-water washing, acid washing, water washing and flotation processes. The water treatment and salt separation system includes pH adjustment, decalcification, heavy metal removal, membrane treatment and evaporation and salt separation, which are used for the purification of water-washed fly ash and salt recovery. The pyrolysis and drying system includes pyrolysis and drying and grinding, which are used for decomposing dioxins and regulating the physical state of the detoxified fly ash. The fly ash resource system realizes the terminal utilization of fly ash through concrete admixture.

2. The method for detoxification and resource utilization of waste incineration fly ash as claimed in claim 1, characterized in that: In the water washing and weight reduction system, the amount of hydrochloric acid added in the pickling process is related to the calcium sulfate content in the fly ash. The higher the calcium sulfate content, the less hydrochloric acid is used.

3. The method for detoxification and resource utilization of waste incineration fly ash as claimed in claim 1, characterized in that: In the water washing and weight reduction system, a water washing process is arranged after the pickling process, the number of water washings is not less than two, and the water-cement ratio is greater than 2:

1.

4. The method for detoxification and resource utilization of waste incineration fly ash as claimed in claim 1, characterized in that: In the water washing and dehydration system, a flotation process is arranged before the last stage of water washing and dehydration.

5. The method for detoxification and resource utilization of waste incineration fly ash as claimed in claim 1, characterized in that: In the pyrolysis drying system, a pulverizer is arranged after pyrolysis drying to increase the fineness of the fly ash.

6. The method for detoxification and resource utilization of waste incineration fly ash as claimed in claim 1, characterized in that: In the fly ash resource utilization system, detoxified fly ash is used to replace part of the fly ash, and the doping amount is about 10-50% of the fly ash doping amount.

7. A method for detoxification and resource utilization of fly ash from garbage incineration, characterized in that: The method is implemented by using the waste incineration fly ash detoxification and resource utilization system as claimed in any one of claims 1 to 6, comprising the following steps: S1. Use the wastewater dehydrated by the washing process in proportion, supplement part of the tap water or evaporation condensate water to wash the fly ash. The liquid phase after dehydration is mainly the washing wastewater of sodium chloride and potassium chloride, and the solid phase is used for further acid washing; S2. The pickling process uses hydrochloric acid for washing, and tap water or evaporated condensed water is added in proportion. Hydrochloric acid is slowly added dropwise. After sufficient mixing, the dehydrated liquid phase is pickling wastewater mainly composed of calcium chloride, and the solid phase is used for further water washing; S3, the water washing process adopts two-stage or three-stage water washing, supplements tap water or evaporated condensed water in proportion, and dehydrates after sufficient stirring; S4. Before the secondary or tertiary water washing and dehydration, a flotation process is used to add flotation agents and modifiers to separate and remove the activated carbon in the fly ash. The scum is suspended on the water surface and outsourced for treatment after separation. The remaining slurry is further dehydrated. The dehydrated liquid phase is used as pre-washing water, and the solid phase is used for further pyrolysis and drying; S5. Set the pyrolysis temperature and time, perform pyrolysis treatment on the fly ash after water washing and reduction, decompose dioxins in the fly ash and dry the fly ash, and treat the dry flue gas to meet the emission standards. The dust generated during the flue gas treatment process is collected and returned to the pyrolysis furnace, and the solid phase after pyrolysis and drying is further ground; S6. Use a pulverizer to further grind the fly ash to increase the fineness of the fly ash and reduce the agglomerates formed after the pyrolysis and drying process of the fly ash. The ground fly ash is detoxified fly ash for further resource utilization; S7. Add detoxified fly ash and other mixing materials in proportion, mix thoroughly, and then sell and apply in the form of green concrete.

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