Study On Treatment And Reuse Technology Of Concentrated Wastewater Of Coal Washing

Concentrated wastewater of coal washing is one of main pollutant sources of coal mine. The waste water produced from the coal dressing process with wet method is difficult to treat, in which there are a lot of slime particles held in suspension by their surface negative charge. The most important objective of this study is to solve the technology problem, search for the effective treatment process and reuse method, accomplish complete closed circuit of coal washing wastewater, thereby alleviate the dangers to the surrounding. At the same time, the effective mechanism which is the foundation to extend the achievement was deeply studied.The characteristic of the concentrated wastewater of coal washing and the reason why the wastewater is difficult to treat were investigated respectively by mensuration of wastewater factors include SS, COD, (?) potential, sludge specific resistance etc. According to the characteristic of the concentrated wastewater of coal washing, a coagulation and sedimetation plan was made and the experiments of screening coagulants and flocculants were carried out. Based on the results, the influence of lime-PAM, calcium carbide residue-PAM, calcium chloride-PAM, and compound drug of calcium and magnesium-PAM on treating effect were investigated respectively. By single factor experiment, the influence of five factors, include dosage, mixing speed, mixing time, sediment time and drug order etc were confirmed. Then, the best process conditions and technical parameters was confirmed by quadrature experiment, and the experiment of the best process conditions was carried out. Based on the experiments, the effect mechanismes of coagulation and sedimetation method to treat concentrated wastewater of coal washing were deeply studied. The effects of components including OH^-, Ca²⁺ and Ca(OH)₂ in coagulation were disgussed too. In order to decrease the corrosion of pipelines and equipments by chloridion, we made compound drug of calcium and magnesium was meade by mixing calcium chloride and magnesium sulfate, and its coagulating effect was studied.The study result indicates that the main reason, why wastewater of coal washing is...