| Aluminum and aluminum alloys slag,also known as aluminum dross,is ahigh yield,polluting industrial solid waste which is produced in molten salt electrolysis of alumina and aluminum smelting production process.Wherein the aluminum content of up to 8~80 %.A large amount of aluminum dross landfill and factory piled,not only caused the waste of aluminum resources but also brings about environmental pollution problems.In this paper,aluminum dross,washed firstly,then sulfuric acid leaching and calcinations were treated.ICP,X-ray diffraction(XRD),X-ray fluorescence(XRF),etc are used to analysis.Preliminary determined the alumina content under optimal conditions.The results are as follows:(1)Soluble sodium and some impurities can be removed by water washing,with the increase of the washing time,PH value of the solution is increased,PH value of the solution becomes stable when washing time reaches to a certain value.After the hydrolysis at 100 °C for 6 hours,AlN of aluminum dross occur extensively hydrolyzed to form a stable Al(OH)3,AlN were significantly reduced,Al4C3 becomes completely hydrolyzed.Al2O3 hydrationweight gain in aluminum dross is small during washing process,trace metals aluminum has hydrolyzed,so the final aluminum content of aluminum dross does not change significantly,the small amount of Al2O3 hydration weight gain and the generation of Al(OH)3 make a slight increase in aluminum dross quality.(2)During sulfate leaching process,the higher the temperature and the longer the leaching time,the higher the aluminum leaching rate,but with the increasing of temperature and leaching time the leaching rate becomes stabilized;With the increase in the concentration of sulfuric acid,the water of leaching solution reduced,aluminum sulfate saturated and hinder the reaction proceeds,which makes the leaching decline,so the sulfuric acid concentration should not be too high,the optimum leaching article is concentration of 15% H2SO4 at 90°C leaching for 5 hours of aluminum dross,the leaching rate of up to 90.2%.(3)Acid leaching and ammonium sulfate were mixed and stirred to adjust PH to 1~3 for forming aluminum ammonium sulfate crystals,then aluminum ammonium sulfate crystals was treated after cleaning,calcined to prepare alumina,which the alumina content is 93.82%,the whiteness is 84.6,the specific surface is 39.79 m2/g.(4)Most of the impurities(e.g.Na,Si,Fe)can be removed via calcination of aluminum dross,as the temperature rised and heating time prolonged,the whiteness and alumina content of the resulting alumina powders both increased,when the temperature and time reache a certain value,the whiteness and alumina content become stabilized,and the process is less affected bycalcination time.(5)The optimum calcination of aluminum dross is 1400 °C and calcination for 4 hours,the alumina content of up to 95.75%,the whiteness is85.2,the specific surface is 38.98 m2/g.(6)Sulfuric acid leaching of aluminum dross is an environmentally polluted,high costs,complicated recovery process,and leaching liquor still need s further treatment,and recovery is relatively low;Compared with the sulfuric a cid leaching process,this operation process is simple,environmentally and more economical,which can achieve high alumina recovery,therefore,it will be a facile,low-cost and non-toxic way to prepare alumina. |
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