The extraction of potassium from a tablet mixture of K-feldspar ore and CaSO4by roasting was studied with a focus on the effects of the decomposition behavior of CaSO4on the potassium extraction process.The roasted sl...The extraction of potassium from a tablet mixture of K-feldspar ore and CaSO4by roasting was studied with a focus on the effects of the decomposition behavior of CaSO4on the potassium extraction process.The roasted slags were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy,and thermogravimetric（TG）analysis.The XRD analysis revealed that hydrosoluble mischcrystal K2Ca2（SO4）3was obtained by ion exchange of Ca^2＋ in CaSO4 and K^＋ in KAlSi3O8.Meanwhile,the intermediate product,SiO2,separated from KAl Si3O8and reacted with CaSO4to decompose CaSO4.The SEM results showed that some blowholes emerged on the surface of the CaSO4particles when they reacted with SiO2at 1200℃,which indicates that SO2and O2gases were released from CaSO4.The TG curves displayed that pure CaSO4could not be decomposed below 1200℃,while the mixture of K-feldspar ore and CaSO4began to lose weight at 1000℃.The extraction rate of potassium and decomposition rate of CaSO4were 62%and 44%,respectively,at a mass ratio of CaSO4to K-feldspar ore of 3：1,temperature of 1200℃,tablet-forming pressure of6 MPa,and roasting time of 2 h.The decomposition of CaSO4reduced the potassium extraction rate;therefore,the required amount of CaSO4was more than the theoretical amount.However,excess CaSO4was also undesirable for the potassium extraction reaction because a massive amount of SO2and O2gas were derived from the decomposition of CaSO4,which provided poor contact between the reactants.The SO2released from CaSO4decomposition can be effectively recycled.展开更多
针对难溶性钾岩的利用问题,研究了富钾板岩-脱硫石膏-碳酸钙体系焙烧产物中钾盐的回收及其浸出动力学.结果表明,焙烧产物主要是Ca_2SiO_4,CaO,K_2SO_4,Ca_3Al_2O_6等,其中K_2SO_4可通过水浸分离提取,在液固比2 m L/g的条件下搅拌浸出,...针对难溶性钾岩的利用问题,研究了富钾板岩-脱硫石膏-碳酸钙体系焙烧产物中钾盐的回收及其浸出动力学.结果表明,焙烧产物主要是Ca_2SiO_4,CaO,K_2SO_4,Ca_3Al_2O_6等,其中K_2SO_4可通过水浸分离提取,在液固比2 m L/g的条件下搅拌浸出,浸出平衡时的钾离子浓度为14.98 g/L,浸出液蒸干结晶物K_2SO_4含量为91.28%.提高温度(T)、增大搅拌速率(r)和减小焙烧产物粒度(d)可提高浸出速率,水浸出过程符合扩散控制的溶解过程模型,通过多元线性回归得到钾盐浸出动力学方程为dc/dt=(9.567′10^(-3)T-1.699′10^(-3)d+7.561′10^(-4)r-2.668)(0.0722-c).展开更多
基金Supported by the National Key Research and Development Program(2016YFB0600904)Sichuan Province Science and Technology Project(2017GZ0377)Sichuan University Postdoctoral Research and Development Fund(2017SCU12017)
文摘The extraction of potassium from a tablet mixture of K-feldspar ore and CaSO4by roasting was studied with a focus on the effects of the decomposition behavior of CaSO4on the potassium extraction process.The roasted slags were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy-dispersive X-ray spectroscopy,and thermogravimetric（TG）analysis.The XRD analysis revealed that hydrosoluble mischcrystal K2Ca2（SO4）3was obtained by ion exchange of Ca^2＋ in CaSO4 and K^＋ in KAlSi3O8.Meanwhile,the intermediate product,SiO2,separated from KAl Si3O8and reacted with CaSO4to decompose CaSO4.The SEM results showed that some blowholes emerged on the surface of the CaSO4particles when they reacted with SiO2at 1200℃,which indicates that SO2and O2gases were released from CaSO4.The TG curves displayed that pure CaSO4could not be decomposed below 1200℃,while the mixture of K-feldspar ore and CaSO4began to lose weight at 1000℃.The extraction rate of potassium and decomposition rate of CaSO4were 62%and 44%,respectively,at a mass ratio of CaSO4to K-feldspar ore of 3：1,temperature of 1200℃,tablet-forming pressure of6 MPa,and roasting time of 2 h.The decomposition of CaSO4reduced the potassium extraction rate;therefore,the required amount of CaSO4was more than the theoretical amount.However,excess CaSO4was also undesirable for the potassium extraction reaction because a massive amount of SO2and O2gas were derived from the decomposition of CaSO4,which provided poor contact between the reactants.The SO2released from CaSO4decomposition can be effectively recycled.
文摘针对难溶性钾岩的利用问题,研究了富钾板岩-脱硫石膏-碳酸钙体系焙烧产物中钾盐的回收及其浸出动力学.结果表明,焙烧产物主要是Ca_2SiO_4,CaO,K_2SO_4,Ca_3Al_2O_6等,其中K_2SO_4可通过水浸分离提取,在液固比2 m L/g的条件下搅拌浸出,浸出平衡时的钾离子浓度为14.98 g/L,浸出液蒸干结晶物K_2SO_4含量为91.28%.提高温度(T)、增大搅拌速率(r)和减小焙烧产物粒度(d)可提高浸出速率,水浸出过程符合扩散控制的溶解过程模型,通过多元线性回归得到钾盐浸出动力学方程为dc/dt=(9.567′10^(-3)T-1.699′10^(-3)d+7.561′10^(-4)r-2.668)(0.0722-c).
