微波对钾长石在碱性条件下低温提钾性能的影响

摘要

A technique of potassium extraction from potassium feldspar at low temperature was introduced.Microwave radiation pre-treatment and feldspar-CaO-NaOH hydrothermal reaction system were employed,so as to achieve potassium extraction in high efficiency and short reaction time.The factors of microwave power,dosage of calcium oxide,the mass ratio of sodium hydroxide to calcium oxide,reaction time and reaction temperature on extraction efficiency of potassium were discussed respectively.The results showed that the optimal conditions were obtained when microwave irradiation power of 800 W,the microwave irradiation time of 15 min,the mass ratio of calcium oxide to feldspar of 0.5,mass ratio of sodium hydroxide to calcium oxide of 9,the temperature of 200 ℃ and the hydrothermal reaction time of 3 h.The potassium extraction efficiency could reach 83.5％ under these conditions.While potassium extraction efficiency was only 65％ without microwave pretreatment.The mineralogical characteristics of pretreated powder and residues were investigated by X-ray diffraction (XRD).The surface and interior of the feldspar were changed after microwave pretreated.The surface became rough and the product(Ca,Na) (Al,Si)2Si2O8 was generated through microwave pretreatment.NaCaHSiO4 was generated after hydrothermal reaction.%介绍了一种钾长石低温提钾方法,即利用微波加热对钾长石粉进行预处理,再通过低温条件下的钾长石-氧化钙-氢氧化钠体系的水热反应,达到在短时间内高效提取钾的效果.分别讨论了微波功率、氧化钙用量、氢氧化钠与氧化钙的质量比、反应时间、反应温度等对钾溶出率的影响,从而得到优化工艺条件.研究结果表明,在微波功率为800 W时预处理15 min、氧化钙用量为0.5 g(以1 g钾长石计)、氢氧化钠与氧化钙质量比为9、200℃水热反应3h条件下提钾效果最佳.在优化工艺条件下钾的溶出率达到83.5％;而相同条件下,未经过微波预处理的样品,其钾的溶出率仅为65％.通过X射线衍射(XRD)对微波预处理后钾长石粉及反应后的滤渣进行了物性分析.结果表明,经过微波预处理后,钾长石表面及内部都发生了改变,其表面变得粗糙,同时生成了(Ca,Na) (Al,Si)2Si2Os等产物;水热反应后得到硅酸氢钙钠(NaCaHSiO4)等产物.