NaOH-Ca（OH）2分解独居石精矿的研究

Study on Decomposition of Monazite Concentrate in NaOHCa（OH）2

为降低独居石分解工艺的加碱量,并提高独居石分解率,本研究在NaOH-Ca(OH)2体系中对独居石精矿进行焙烧分解,采用XRD对焙烧产物进行物相分析,并结合焙烧矿中稀土元素在盐酸中的浸出率判断独居石分解效果.实验分别研究了NaOH添加量、Ca(OH)2添加量、焙烧温度以及焙烧时间对独居石精矿分解的影响.结果表明,在NaOH-Ca(OH)2体系中,独居石精矿分解的最佳工艺条件:NaOH添加量为25%,Ca(OH)2添加量为20%,焙烧温度为800℃,焙烧时间为1. 5 h.该焙烧条件下独居石全部分解为稀土氧化物,浓盐酸对稀土浸出率可达到98%左右.与现有工业生产工艺相比,本研究工艺中碱添加量降低55%左右,独居石分解率提高2%左右.

In order to decrease alkali dosage and increase decomposition rate of monazite, decomposition experiment of monazite concentrate in system of NaOH-Ca(OH) 2 was implemented by roasting.The roasted products were characterized by using X-ray diffraction.The decomposition effect of monazite was further judged through leaching rate of rare earth in hydrochloric acid.The influence factors for roasting process, such as roasting temperature, NaOH dosage, Ca(OH) 2 dosage and roasting time were investigated.The optimum roasting decomposition parameters are proposed as the following: roasting temperature of 800 ℃, NaOH dosage of 25 %, Ca(OH) 2 dosage of 20 %, and roasting time of 1.5 h.With these optimum parameters, rare earth phase transformed from REPO 4 into REO.Leaching experiments demonstrated that leaching rate of rare earth in concentrated hydrochloric acid reaches up to 98 % in these optimum parameters.Comparing with index of industrial production process, alkali dosage in this process reduces about 55 %.Additionally, decomposition rate of monazite increased about 2 %.