A method of using sludge to treat fly ash

Abstract

The invention discloses a method and equipment for treating fly sh by sludge. The method comprises the following steps: a mixture of the fly ash and the sludge is forcedly stirred to obtain mixed mud; the mixed mud is hydrothermally treated to obtain a hydrothermal treatment product; the hydrothermal treatment product performs solid-liquid separation through a pressing filter mode to obtain hydrothermal pressing filter liquid and a hydrothermal pressing filter solid; a biomass is added in the hydrothermal pressing filter solid to form a pyrolysis mixture; the pyrolysis mixture is pyrolyzed to obtain pyrolysis residues; the pyrolysis residues serve as general solid wastes for backfilling or serve as inorganic materials for use; the hydrothermal pressing filter liquid performs anaerobic fermentation to generate gas and fermentation liquid; the fermentation liquid generated by fermentation is purified; and the treated water is qualified for emission. The invention further provides equipment for realizing the method. The method uses the sludge for realizing detoxification of the fly ash and stabilization, thoroughly eliminates dioxin substances in the fly ash to prevent secondary pollution, and realizes harmless treatment of the fly ash.

Description

technical field [0001] The invention relates to resource utilization of fly ash, in particular to a method for treating fly ash with sludge and equipment for realizing the method. Background technique [0002] At present, the domestic waste incineration process has become the mainstream technology for waste disposal in large and medium-sized cities in my country. Incineration fly ash accounts for 1%-5% of the total mass of incinerated waste. If the dosage of slaked lime and other chemicals added in the flue gas purification treatment is added, it accounts for 3-7% of the total mass of incinerated waste. According to statistics, my country's domestic waste incineration and disposal capacity has exceeded 55.05 million tons, and 2.2 million tons of domestic waste incineration fly ash will be produced every year. Fly ash has been included in the National Hazardous Waste List (HW18). The conventional method is to use cement solidification and other methods to stabilize the harmf...

AI Technical Summary

Problems solved by technology

This not only has high processing costs, occupies land resources, and is prone to secondary pollution

The main reason is that the solidification and stabilization of fly ash mainly depends on the hydrated silicate system, but the high chlorine content in the fly ash (the average mass percentage is higher than 15%) directly hinders the hydration process of the silicate system and reduces the strength of the solidified body. As a result, the leaching rate of harmful substances becomes higher, so when the hydrated silicate system is used to solidify and stabilize fly ash, it is necessary to pre-wash the fly ash to remove chloride ions in the fly ash, which makes the treatment process more complicated

In terms of fly ash recycling, some researchers have proposed to use fly ash as an additive in the production of building materials, but my country’s cement standards have strict control standards for chlorine content, and chloride ions will cause serious electrochemical corrosion and corrode reinforced concrete. In the middle of the steel structure, it will also reduce the strength of the cement

Therefore, dechlorination and solidification of heavy metals are a bottleneck problem in the harmless and resourceful utilization of fly ash

Images