At present, the methods developed and applied to the harmless stabilization of incineration fly ash at home and abroad can be divided into three types: high temperature treatment, wet chemical treatment and fixed stabilization. In addition, there are biological leaching extraction, high temperature thermal separation and other methods.
High temperature treatment: High temperature treatment technology mainly includes melting (vitrification), high temperature sintering and high temperature calcination. The volume of fly ash after high temperature treatment is reduced by about 2/3, and the organic matter in fly ash can be decomposed at high temperature. So as to realize the effective and harmless treatment of fly ash. However, the cost of this treatment process is high, and it is difficult to widely promote and use at present. Fixation and stability: Fixation and stability mainly include four types: bone cement fixation, chelating agent fixation, high pressure fixation and reuse fixation. Because the government has strengthened the supervision of hazardous waste, most of the fly ash in China is stabilized by chelation. This method combines the advantages of cement fixation and chelating agent fixation. Cement and chelating agent are added in the curing process, which effectively prevents the leaching of heavy metals and dioxins, and makes up for the shortcomings that the fixed leaching of cement is not up to standard and the chelating agent is expensive. Because of its economy and applicability, this method has been adopted by fly ash treatment systems of many garbage incineration plants and achieved good results.
Resource utilization of slag
Advantages of making baking-free brick with slag: The baking-free brick with slag from garbage incineration can be used as the main raw material, with a content of more than 80% (including aggregate), turning waste into treasure and turning harm into benefit. The baking-free brick project has a competitive advantage in the market. The state strictly restricts the production of clay bricks, and non-burning bricks do not use clay as raw materials or coal as fuel, thus protecting cultivated land and protecting the environment. Brick-making is mechanized production, and the production process is simple, easy to master and applicable everywhere. The production of baking-free bricks is formed by the bidirectional action of equipment pressing and high-frequency directional vibration after the materials enter the standard mold box. The appearance of brick is very regular, the product density is high, and the technical indexes are better than those of clay sintered brick. At present, among all the technologies for producing building materials from industrial waste residue, the baking-free brick project has the least investment and the fastest effect.
Brick-making process: After the slag is sorted, it passes through conveying system, batching system, mixing system, distributing system, molding system, demoulding system, discharging system, automatic stacking system, hydraulic system and electrical control system. Slag, cement, crushed stone and stone powder are pressed and molded according to the ratio of 4:15:15:15 to achieve the purpose of resource utilization.