PAFC Synthesis By Fly-ash From Shengli Power Plant And Evaluation Of Its Application

Fly ash is a main solid waste with high aluminum content, which is discharged from power plant. It can be used to prepare Polyaluminium ferric chloride(PAFC) flocculants as a kind of cheap raw material. The objective of this work is to obtain high quality PAFC flocculants under conducting hydrochloric acid-soluble reaction and adjusting Al/Fe(molar ratio) and base level with calcium aluminum powder. The product, PAFC, can meet all the quality requirements: The content of aluminium oxide in the liquid and solid fraction is approximately 8~10 % and 30 %, respectively, and the basicity is about 68.62% with a p H value of 4.7. Therefore, the product achieved meets all the quality requirements.Aluminum in the fly ash exist in the form of mullite with high polymerization. Therefore, in order to improve the dissolution rate of aluminum and iron, raw material pretreatment was to be carried out conducted and the optimal conditions were obtained: Na OH was chosen as activation agent and 200-mesh fly ash was roasted and activated for 2 hours under 400℃ with Na OH was chosen as activation agent. During the acid-soluble reaction of fly ash and hydrochloric acid, four primary parameters(reaction temperature, reaction time, liquid-solid ratio and acid concentration) which affected the dissolution rate of alumina and iron oxide in the fly ash were determined: Reaction temperature, reaction time, liquid-solid ratio and acid concentration. The optimal conditions were as following: acid-soluble reaction temperature was 105℃; hydrochloric acid concentration was 20% and liquid-solid ratio was 3:1. The optimal Al2O3 content was 10.76% with Fe content of 2.68% in the products obtained at a reaction temperature of 85℃, with a holding time of 3h, calcium aluminum powder content of 0.20 g/m L and basicity of 68.62%. The products observed was red-brown while the solid power was yellow.In this research, the PAFC was applied to the actual oilfield sewage treatment process and the flocculation effect of dosage PAFC product and water p H. The results showed that oil content in the sewage could be decreased from 206mg/L to 27.3mg/L with optimum PAFC dosage of 100mg/L. Meanwhile, the PAFC was found to be utilized in the wider p H value of 5~9.In conclusion, polyaluminium ferric chloride(PAFC) flocculation agent obtained from fly-ash of Shengli Power Plant showed better degreasing performance with lower production cost. This work could turn the fly ash into wealth, make full use of resources and improve the economic efficiency, as well as satisfy the environmental requirements, enhance it has broad application prospects.