亚熔盐分解钾长石矿样中钾铝硅的分离  

Separation and recovery of potassium, aluminum and silicon after decomposition of potassium feldspar using sub-molten salt method

作　　者：董安瑞 罗孟杰 姜炜 刘程琳 李平[1] 于建国 Anrui DONG;Mengjie LUO;Wei JIANG;Chenglin LIU;Ping LI;Jianguo YU(State Key Laboratory of Chemical Engineering,School of Chemical Engineering,National Engineering Research Center for Integrated Utilization of Salt Lake Resources,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化工学院联合化学反应工程研究所国家盐湖综合利用工程技术研究中心

出　　处：《过程工程学报》2018年第5期972-980,共9页The Chinese Journal of Process Engineering

基　　金：国家自然科学基金资助项目(编号:21376085;21776089)

摘　　要：采用KOH亚熔盐法常压低温分解河北钾长石矿粉,回收过量碱后,用硫酸溶解固渣,得含高浓度钾、铝、硅的母液;采用溶胶-凝胶法和分步醇析法从母液中制备硅凝胶、钾明矾和硫酸钾,钾明矾热解制备氧化铝.结果表明,钾长石矿中各组分含量分别为K2O13.13wt%,Al2O316.66wt%,SiO258.28wt%.在H＋浓度3.80mol/L及95℃条件下母液易形成硅凝胶,脱硅率达98%以上,SiO2含量大于99.0%,比表面积大于700 m2/g,孔容约为1.0 cm^3/g,孔径为5-6 nm;对脱硅母液分步醇析,在25℃、醇料体积比为1时,优先析出钾明矾,铝析出率达98%,降温至5℃并增大醇料体积比至2,可从母液中结晶析出硫酸钾,钾回收率达89%.Potassium feldspar is the typical insoluble potassium ore with enormous reserves in the whole world, which contains mainly potassium, aluminum and silicon valuable elements. It will be of great strategic significance to produce soluble potassium fertilizer, aluminum potassium sulfate, alumina and silica gel from potassium feldspar. Instead of the traditionally high temperature roasting（more than 700 ℃）, in this work, potassium feldspar from Hebei province was decomposed using KOH sub-molten salt method at low-temperature（less than 240 ℃） and normal-pressure. The excess unreacted KOH was recovered through extraction of ethanol aqueous solution, and then the decomposed sample was dissolved with 2 mol/L sulfuric acid solution to transfer K, Al, Si in the mineral powder into the liquid phase, called the mother solution for the separation and recovery of K, Al, Si. Here, sol-gel method and stepwise alcohol precipitation method were used to separate and recover Si, Al and K from the mother solution. The preparation conditions of silica gels, aluminum potassium sulfate and K2SO4 from the mother liquor and the conditions to produce Al2O3 from KAl（SO4）2·12 H2O pyrolysis were investigated. An efficient and clean technological route for the comprehensive utilization of potassium feldspar resources was developed. The results showed that the main compositions of potassium feldspar were K2 O 13.13 wt%, Al2O3 16.66 wt% and SiO2 58.28 wt%. Silica gel was easy to be formed in the mother solution at 95 ℃and concentration of H＋ 3.800 mol/L, the desilication rate was over 98%, and SiO2 content of silica gel was more than 99.0%. The BET surface area was more than 700 m2/g, pore volume was about 1.0 cm^3/g and pore size was 5-6 nm. The separation of potassium and aluminum from the mother solution was enhanced by the stepwise alcohol precipitation. Firstly, aluminum potassium sulfate with high purity was precipitated at 25 ℃, the volume ratio of ethanol to feed 1.0, stirring speed 200 r/min, time 5 min, the preci

关 键 词：钾长石 硅凝胶 醇析 钾明矾 热解 氧化铝 

分 类 号：TQ170.6[化学工程—硅酸盐工业]