Selection Of Cosolvent In The Study On Extraction Of Alumina From Fly Ash Junggar Coalfield

Fly ash as the main waste of coal-fired power plant has become a serious environmental pollution by industrial solid waste.But it is actually a high value of the material,it can be widely used in agriculture,chemical industry,construction and a series of industry.Therefore, the use of fly ash focus of attention of the world’s people.Based on the analysis of the current development of fly ash at home and abroad,In this paper,made a comprehensive analysis Of the Junggar coal fly ash.Firstly,the physicochemical properties and components fly ash of Jungar coalfield are studied by XRD,SEM and EDX analysis method. The analyzed result shows that the fly ash’s aluminum mainly exists in mullite and aluminum-silicate glass phase. In this, the quantity of SiO2 is 43.96%, the quantity of Al₂O₃ is 45.52 wB % and other compositions’quantity is 10.52%。Selected HCl,HClO₄,HNO₃ reaction with fly ash.And analysis reaction results by SEM,EDX method,results from the analysis to determine the most beneficial types of solid state reaction acid is HCl.On this basis,Respectively use CaO、KF、Na₂CO₃、natural soda these different substances to help solvent.Comparison of them on the effect of extraction of alumina from fly ash to determine the optimal cosolvent.Use CaO as cosolvent,the optimum process parameters are:the molar ratio of CaO and SiO2 in the fly ash is 0.6,the leaching rate of aluminum is 40.7%. Use KF as cosolvent,by single factor experiment,Finally determined the best experimental conditions are:the mass ratio of fly ash and KF is 2:1;Calcination temperature is 800℃;Calcination time is 60min;Acid leaching reaction time is 60min;Acid leaching temperature is 90℃;the acid concentration is 6mol/L;Ratio of liquid and solid is 6:1.Under these conditions,The leaching rate of aluminum can reach 95%. Use Na₂CO₃ as cosolvent,by single factor experiment,Finally determined the best experimental conditions are:the mass ratio of fly ash and Na₂CO₃ is 1:1.5;Calcination temperature is 900℃;Calcination time is 150min;Acid leaching reaction time is 20 min;the acid concentration is 15%;Ratio of liquid and solid is 4:1.Under these conditions,the leaching rate of aluminum can reach 97.3%. Eventually,this research substituted natural soda for analytically pure Na₂CO₃ to carrying out capability improving for fly ash.Finally made sure the best quantity proportion of fly ash and natural soda is 1:1.6,at this time,theleaching rate of Al2O3 is 84.6 %.