Obtain Al₂O₃from Desilicicate Flyash By Low-Na Method

It is important to looking for a new aluminum source now, with the gradualdepletion of bauxite resources becoming more and more serious. After the componentanalysis of fly ash which discharged by the electronic power plant in north of Shanxi,the result showed that content of the Al₂O₃in fly ash was about41%. The fly ash withhigh alumina content is endemic to China, if we can refine the Al₂O₃in fly ash, it willmeet the shortage of the aluminum industry and sustain the industry’s development.The fly ash was used as the main raw material which produced in Shouzhouelectronic power plant in Shanxi province, Alumina was extracted by low-Na limesintering method after pre-desiliconizing. The influence of alkali ratio, sinteringtemperature, sintering time and dissolution process of dissolution time, the ratio ofliquid to solid, caustic soda content and carbon alkali content on the extraction rate ofAl₂O₃and Na2O were studied. This method simplified the traditional lime sinter process,realized the dry sintering and reduced the sintering heat consumption by30%. Thistopic controlled the amount of alkali, overcame the obstacle that large consumption ofalkali,and high energy consumption in the industrialized production of alkali-limesintering method by dry sintering, and after reducing the content of alkali in the red mud,it could be used to produce cement. Al（OH）3was prepared from the eluate of sinteringmethod by carbonation method,the alumina was obtained by high temperature and lowsodium after the pretreatment of Al（OH）3. Optimized the conditions of separatingGallium and Aluminum from the mother liquor, and reduced the yield of calciumaluminate, obtained the optimum conditions of maximize separation of galliumaluminum.The fly ash, desilicicate ash, clinker and red mud were analyzed by XRD, SEM.The phase composition and changes of chemical composition in the process were determined. The process of low sodium sintering extracting the alumina fromdesilication fly ash was carried out.â‘ The best condition for desilication were asfollows: charge ratio of alkali and aluminum was0.4;saturated calcium, sinteringtemperature was1280℃;sintering time was30minutes; clinker dissolving temperaturewas85℃;dissolving time was10minutes and the ratio of liquid and solid was10:1;thecontent of Na2CO3was100g L-1in dissolving liquid, dissolving rate of Al₂O₃and Na2Owere more than81%and80%.â‘¡The best condition of preparing aluminum hydroxidefrom the mother liquor of sintering method was explored by carbonation method. Thealumina with high temperature and low sodium can be prepared after roastingpretreatment process at1000℃, adding1%ammonium fluoride and1%acetic acid assodium removal agent to obtain low sodium alumina after being calcined at hightemperature, then sodium oxide content and α-Al₂O₃content could meet therequirements of low sodium high temperature alumina quality.â‘¢Gallium andaluminum can be separated at these conditions:30minutes, flow rate was100mL min-1L-1and the temperature was40℃. The ratio of Al₂O₃and Ga₂O₃can bedecreased from1028to286, the production of calcium aluminate can be reduced andthe production of technical and economic indicators can be improved.