Treatment method and system for washing and dechlorinating waste incineration fly ash and evaporating, grading and crystallizing washing liquid

Abstract

The invention discloses a treatment method and system for washing and dechlorinating waste incineration fly ash and evaporating, grading and crystallizing washing liquid. The method comprises the following steps: pulping the waste incineration fly ash, and performing multi-stage elution to obtain washed fly ash and washing liquid; purifying the water washing liquid to obtain clear liquid and precipitated slurry; adjusting the pH value of the clear liquid to obtain an evaporation raw material liquid, and sequentially carrying out preheating, falling film heat exchange, forced circulation heat exchange, evaporative crystallization treatment, sodium chloride crystallization separation, nanofiltration membrane treatment and potassium chloride crystallization separation to obtain potassium chloride and sodium chloride products; and obtaining sludge and clear liquid through desliming treatment of the sediment slurry, and obtaining fly ash through drying the sludge and the washed fly ash. The multi-stage countercurrent and alkaline water washing technology is adopted, water consumption is low, raised dust is avoided, the dechlorination effect is good, and the heavy metal leaching rate is low; divalent ions in feed liquid are intercepted by adopting a and nanofiltration membrane treatment technology, so that the quality of crystalline salt is effectively improved, long-term stable operation of the system can be ensured, and cyclic utilization and zero emission of process water are realized while the consumption of clear water is reduced.

Description

technical field [0001] The invention relates to a treatment method and system for waste incineration fly ash, in particular to a method and system for washing chlorine from waste incineration fly ash and evaporative fractionation and crystallization of water washing liquid, and belongs to the field of reprocessing and utilization of waste incineration fly ash. Background technique [0002] Waste incineration fly ash is a powder substance with light bulk density and small particle size collected in flue gas pipes, flue gas purification, separators and dust collectors during the waste incineration process, accounting for about 30% of the domestic waste treatment volume. %-5%. At present, the use of cement kiln co-processing fly ash technology is an effective technical means to realize the harmless, reduction and resourceful disposal of waste incineration fly ash. However, a large amount of chlorine, potassium and sodium in fly ash will affect the quality of clinker and cement...

AI Technical Summary

Problems solved by technology

However, in the three-stage water elution desalting process, the addition of three solubilizing agents and the consumption of a large amount of water lead to waste of resources and increased costs; the miscellaneous salts obtained by the process of removing very small amounts of miscellaneous salts are hazardous wastes, which should be landfilled or incinerated. It will also be treated according to hazardous waste standards; finally, the purity of the obtained salt product is only above 70%, and the salt quality is low

Therefore, the prior art urgently needs improvement for the above-mentioned defects existing in the recycling method of garbage fly ash harmless resources

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