低品位锂辉石矿碱浸脱硅过程研究

Desilication Process in Alkaline Leaching of Low-Grade Spodumene Ore

以江西低品位锂辉石原矿为原料,以氢氧化钠溶液为反应介质,研究了锂辉石矿脱硅浸出过程中Si、Li、Al元素的浸出行为,系统考察了浸出时间、搅拌速率、浸出温度、碱矿比(碱与锂辉石质量比)和碱质量分数对Si、 Li、 Al元素浸出率的影响。利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对锂辉石矿和浸出固相的矿物组成和微观形貌进行表征,并分析了浸出过程。采用中心复合设计(CCD)响应曲面法优化反应因素,当浸出时间为3.7 h、浸出温度为215℃、碱矿比为1.15、碱质量分数为16%时,Si、Li元素的浸取率预测值分别为74.55%和3.31%,相应的试验值分别为73.41%和3.33%,预测值与试验值接近,误差较小。

Spodumene is one of the exploited and utilized lithium resources in the world,which is often associated with feldspar,quartz and other minerals.There are a lot of silicon resources in spodumene,so it is of great value to synthetically utilize the silicon resources in spodumene.The spodumene ore from Jiangxi Province was used as raw material,while the NaOH solution was applied as reactant.The leaching behaviors of Si,Li,Al from spodumene ore were studied.The influences of different parameters,including leaching time,stirring speed,leaching temperature,alkali-to-ore mass ratio and NaOH mass fraction on the leaching rates of Si,Li,Al were investigated.The mineralogical structure and microstructures of spodumene ore and concentrate were characterized by X-ray diffraction(XRD)analyzer and scanning electron microscope(SEM),and the desilication leaching process was analyzed as well.Central composite design(CCD),a kind of response surface methodology,was employed to investigate the effects of leaching time,leaching temperature,alkali-to-ore mass ratio and NaOH mass fraction on the leaching rates of Si and Li.The optimal leaching conditions were thereby obtained as following:leaching time 3.7 h,leaching temperature 215℃,alkali-to-ore mass ratio 1.15,NaOH mass fraction 16%.Under the conditions,the optimal predicted values were:leaching rate of Si 74.55%,leaching rate of Li 3.31%,while the corresponding experimental results were 73.41%and 3.33%,respectively.The errors between the predicted and experimental values were ignorable,which indicated that the established models could analyse and predict the desilication process in alkaline leaching of low-grade spodumene ore accurately and reliably.