微波辅助条件下低温水热法分解钾长石

Microwave-assisted Decomposition of K-feldspar at Low Temperature in Hydrothermal Reaction

研究了微波辅助条件下钾长石低温提钾过程.微波预处理后的钾长石,在氢氧化钠-氧化钙混合碱液条件下进行水热反应.利用X射线衍射和扫描电镜手段分析了预处理前后钾长石及反应残渣的矿物特性.讨论了微波功率、CaO用量、NaOH与CaO质量比、反应时间、反应温度对钾溶出率的影响,结果表明:在静态水热反应情况下,钾提取率可达77.6%.优化的工艺条件为:微波预处理功率800 W,预处理时间15 min,每克钾长石的CaO用量为0.5 g,NaOH与CaO的质量比为9,200℃下水热反应3 h.采用不同动力学模型对钾长石分解过程进行拟合,确定钾长石分解过程符合Y=1-(1-f)^(1/3)模型.微波辅助提钾工艺可以有效缩短反应时间并提高提钾效率.

Extraction of potassium from K-feldspar under microwave-assisted condition at low temperature was studied in this paper. Hydrothermal reaction of pre-treated K-feldspar was carried out in mixed alkaline solutions containing NaOH and CaO. The mineralogical characteristics of raw K-feldspar, pre-treated K-feldspar and residues were determined by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The effects of microwave power, dosage of calcium oxide, the mass ratio of sodium hydroxide and calcium oxide, reaction time and reaction temperature on extraction efficiency of potassium were discussed respectively. The results show that potassium dissolution efficiency can reach 77.6% in static hydrothermal process. The optimal conditions were obtained when microwave irradiation power reaches 800 W for 15 min ,the mass ratio of calcium oxide to feldspar is 0.5,the mass ratio of sodium hydroxide to calcium oxide is 9,the temperature is 200 ℃ ,and the hydrothermal reaction time is 3 h. The dynamic models were used to fit the decomposition process of potassium feldspar, and the Y = 1-（ 1-f ）1/3 model was consistent with the decomposition process of potassium feldspar. Microwave-assisted extraction method was demonstrated to be an excellent alternative for short reaction time and higher extraction efficiency.