Study On The Ecological Technology Of Extracting Aluminium From Coal Fly Ash By Ammonium Salt Calcination Method

The ecological utilization and mineralogy of Coal Fly ash?CFA?from DaTang thermal poewer plant which located in central inner Monglia were assessed.Based on prior knowledge and its advantages of riching Al₂O₃ and SiO₂.methods of preparing nanometer powders and hydrothermal method could be treated as effective approach.Aim at the amphoteric aluminum,designed process of "roasting using mix roasting additives then leaching by water" to carry out experimental.by using ammonium salt roasting method obtained water extract could be used to synthesis nanoscale ?-Al₂O₃ through the progess of“homogeneous precipitation intensified with ultrasound”.formation mechanism of precipitation was explored through characterizing intermediate products,ammonium salt roasting method obtained water leaching residue was used as synthetic reagents for Al-substituted tobermorite,the mechanisms of crystallizating and optimizing experimental conditions was explored.Combining the theoretical analysis and test techniques.results showed that the contents of Al₂O₃ in CFA more than 39%.main mineral phase is mullite.Lower activity of mullite which clad by glass further hinders the extraction rate from CFA.a new roasting activation process of CFA using the composite additive made of ammonium sulfate??NH4?2SO₄?and sulfuric acid?H2SO₄?was carried out.The ultrapure water as leaching agent after roasting activation process.products and liquid leached residues obtained under different sintering conditions were characterized The results show that as the optimal calcination condition is 400? for 2h in air with a heating rate of 7 ?·min-1,molar ratio of SO₄2-in mix roasting additives and Al₂O₃ in CFA is 4,molar ratio of H2SO₄ and?NH4?2SO₄ is 1.5,Under the optimal processing condition,the alumin a?Al₂O₃?ex traction efficiency from as-sintered coal fly ash can reach 84.7%.This paper introduces a new producing technology of Ammonium aluminum carbonate hydroxide?AACH?,AACH was synthesis by the ultrasonic atomization and homogeneous precipitation method.using the mixture solution of NH4Al?SO₄?2 and NH4HCO3.The homogeneous precipitation intensified with ultrasound.The characterization of precursor was investigated by the X-ray diffraction analysis,scanning electron microscope,laser granularity analyzer.The results show that under the optimal condition of pH is 8,ultrasonic power is 120W,ultrasonic frequency is 40Khz.Products on these conditions are good dispersion and particle size distribution is 50-70nm.Al₂O₃ extracted slag of coal fly ash by H2SO₄ and?NH4?2SO₄ binary mixtures roasting technology is a kind of secondary waste material.The alkaline hydrothermal activation synthesis of tobermorite from residue after extracting aluminum from coal fly ash,in order to adequately use the active residue starting CaO-Al₂O₃-SiO₂-H2O system are priority for preparing with different Ca/Si molar ratios of 0.5,0.67,0.83,1 and 1.16 different temperatures ranged from 140 ? to 260? and time ranged from 12h to 24h in each experimental condition.The main aim was to investigate quantitatively the influence of temperature and aluminium content on phase stability.The results show that the dealuminated coal fly ash residue can be used for production of Al-substituted tobermorites under hydrothermal condition,Al3+ is inserted into tobermorite and plays a role of stabilization during the hydrothermal reaction.The paper presented two new technology for the resource utilization of CFA innovating is to reflect the direction.Not only can solve the social and environmental problems caused by CFA,but also can create more economic value in the realization of high efficient utilization of CFA...