Acid Leaching Method Of Extracting Alumina From Fly Ash

We have a certain content of Bauxite in our country, and our use of aluminum is larger, but the gap increases year by year, the alumina content in the fly ash is higher, It can be a extract alumina resources instead of bauxite. Extracting alumina from fly ash, Not only solved the problem of the aluminium production,also solve the environmental problems brought by fly ash.The alumina acid leaching method was used to extract the fly ash in this paper, useing high concentration of sulfuric acid as solvent,and use the fluoride as cosolvent, dissolved aluminum in fly ash; After the deep desilication,refined sodium aluminate solution can be made; Although acid leaching from coal ash in aluminum technology is mature,But there has been in the process of acid soluble low leaching rate, fluoride pollution of the environment, and other issues,This study adopts the method of orthogonal test,,By optimizing the experimental conditions, not only increase the leaching rate of aluminium, but also greatly reduces the pollution of the environmentThe Studies have shown that:When dissolution temperature reached boiling, the concentration of sulfuric acid for is 12 mol/L, Solid-liquid ratio is 1:3?the dissolution time is 120 min?the quality ratio of fluoride and fly ash is 0.04?the leaching rate of aluminum can reach 91.2%;On the premise of no lower leaching rate, toxic fluoride content reduced by half.Acid leaching method of extracting alumina from fly ash, By acid solution, alkali soluble iron removal, Deep desilication get the Unsaturated sodium aluminate solution, Its content was determined by chemical analysis, with the result that Silicon quantity index for 400 Nk=42.6g/L,?k=1.86?Because of the low solubility of sodium aluminate solution, Can't spontaneous decomposition of Al (OH) 3 crystal, So the test using NaHCO3 was added to improve the decomposition rate., Mainly studied under the effect of additive NaHCO3 unsaturated sodium aluminate solution of dynamic equation of the process, Determine the dynamics equation of sodium aluminate solution of points as follows: Among them:the reaction series n=1?dimensional m=1/4?different temperature of reaction rate Kr?the apparent activation energy Ea=30.44 KJ/mol?the former factors A= 5.40 x 103. Under the action of additive NaHCO3, this reaction is level 1, The decomposition rate equation of sodium aluminate solution is Research for the production of alumina with unsaturated sodium aluminate solution, reducing energy consumption, and provide theoretical basis for industrial production.Al(OH)3under the different temperature after the calcine,Al2O3 can be obtained.The results showed that when the temperature is 850?,get ?-Al2O3,when the temperature is 1200?,get ?-Al2O3.By means of XRD, SEM, laser particle size analysis and chemical composition analysis method the samples were characterized.