Study On Dissolution Characteristics Of Gallium And Aluminum From Fly Ash Activated By Roasting With Sulfuric Acid Or Sulfate

Today, most countries in the world genetate power with coal,which will product a lot of fly ash during the generation process, so how to efficiently use the fly ash has become a problem to be solved. In our country, coal is the main source of power, which occupies more than 70%. At the same time, every year there is about 30% mining coal used to generate electricity, so it will inevitably lead to the generation of a large amount of fly ash.As the large industrial waste emissions in the world,fly ash will cause significant harm on the enwironment and human health without effective use.Using the high aluminum powder coal ash that comes from Shenhua Zhungeer power plant as raw material, which also contains rich gallium,the study adopted defferent process to dissolve gallium and aluminum in the fly ash,then we can get solution containing gallium and aluminum under different systems.Conduct visible light test to the ions in the solution and analize solid samples by various means, such as XRD, SEM, FTIR, particle size test, etc.During gallium recycling,there will be aluminium salts, carbon and silicon material, that also have significant economic value,which can realize the comprehensive utilization of fly ash.In sulfuric acid roasting-water soluble system, the optimum roasting activation conditions are as follows:the ratio of acid to fly ash is 1.2:1, calcination temperature is 300℃, roasting reaction time is 3 h, water immersion temperature is 90 ℃, water immersion time is 1 h, at this time the dissolution rate of gallium and alumina reach 76.96% and 89.79% respectively; the optimum calcination conditions are as follows:the amount of the addition is 5%, calcination temperature is 500 ℃, calcination time is 3 h, the ratio of acid to fly ash is 1.2:1, at this time the dissolution rate of gallium and alumina reach 76.96% and 95.86%respectively.In sulfuric acid roasting-hydrochloric acid solution system, the optimal conditions are as follows:the ratio of actual hydrochloric acid dosage to theoretical hydrochloric acid dosage is 1.4:1, the acid leaching reaction temperature is 140℃, heat preservation time of acid leaching reaction is 4 h, the dissolution rate of gallium and alumina can reach 72.32% and 82.97% respectively.In sulfuric acid roasting-alkali soluble system, the optimal alkali developable condition are as follows:the concentration of sodium hydroxide solution is 5 mol/L, the ratio of actual alkali dosage to theoretical alkali dosage is 1.5:1, the reaction temperature is 180 ℃, holding time is 5 h,under these conditions the dissolution rate of gallium and alumina can reach 88.41% and 81.89%, respectively.In sulfate roasting-alkali soluble system, it is concluded that the best alkali dissolving conditions are as follows:the concentration of sodium hydroxide solution is 5 mol/L, the ratio of actual alkali dosage to theoretical alkali dosage is 1.75:1, the reaction temperature is 180 ℃, holding time is 5 h,under these conditions the dissolution rate of gallium and alumina can reach 90.06% and 86.65%, respectively.