Study On Production Of PAC By Coal Gangue And Its Application

There is a long history of coal mining in China. Every year we have a big production of coal. Mining coal producing a large amount of coal gangue brought serious environmental pollution and ecological damage. Stacking a large number of coal gangue wasted resources undoubltely. Therefore, its treatment, disposal and study of resources are imperativeInorganic polymer flocculants is a new type of water treatment pharmacy which developed on the basis of traditional aluminum and molysite. Inorganic polymer flocculants not only has a better coagulant performance than conventional flocculants to deal with mine water, but also has lower prices than organic polymer flocculants. Coal gangue is rich in the main ingredients which are preparation of inorganic polymer flocculants; it is natural raw materials of the preparation of inorganic polymer flocculants. If this part of aluminum can be used, enormous social and economic benefits will be made.In this study we used coal waste as raw materials to prepare efficient inorganic polymer flocculants whose name is PAC (Poly aluminum chlori). Besides, through the single-factor experiments, we found the optimum operating conditions and got a better result. Main contents and conclusions are as follows:(1) Through chemical analysis of gangue, the content of silica is 51.79%, the content of Fe2O3 and AI2O3 are 3.98% and 22.58% respectively.(2) The results of the single-factor experiments show that:the optimum reaction conditions for coal gangue at the condition of reaction temperature is 105-108℃(azeotropic temperature of hydrochloric acid and water) and normal pressures, we use the mass fraction of 20% of the hydrochloric acid to lixiviate aluminum of gangue as follows:calcined temperature is 650℃, acid leaching time is 3h, acid capacity is 0.01908mol/g, solid-liquid ratio is 1:4, leaching rate is 63.7%. (3) Through analysis basicity and the concent of Al2O3 of homemade PAC at different producting conditions, we got optimal polymerization conditions: polymerization time is 30min, the polymerization temperature is 60℃, pH is 3.7. salinity basic degree of the self-made PAC is 60%, content of is Al2O3 10.06%, which comply with national standards chloride (GB 15892-1995) completely.(4) Through beaker experiments, we studied the coagulation characteristics of PAC which are home-made and marketed respectively. The experimental results show that the optimal conditions of treating kaolin simulation wastewater using home-made PAC flocculants are as follows:dosage is 500mg/L, wastewater pH is 8, the sedimentation time is 15min, stirring speed is 200r/min; however, the optimal conditions of using commercial PAC are as follows:dosage is 500mg/L, wastewater pH is 9, the sedimentation time is 15min, stirring speed is 200r/min. Moreover, the treatment efficiency using home-made PAC is higher than that of the commercial PAC.