采用(NH_(4))_(2)SO_(4)焙烧-水浸工艺提高菱镁矿的利用效率

Improvement of utilization efficiency of magnesite by(NH_(4))_(2)SO_(4)roasting–water leaching process

研究采用硫酸铵焙烧—水浸工艺提高菱镁矿的利用效率,结合XRD和TG-DTA分析以及对比硫酸铵焙烧MgO的物相变化得到焙烧过程中矿相的转化过程。实验结果表明,在菱镁矿粒度为~74μm、硫酸铵与菱镁矿物料摩尔比为1.6:1、焙烧温度为475℃和焙烧时间为2 h的条件下,镁的提取率达到98.7%。反应中物相转化过程可以概括如下:MgCO_(3)先转变为(NH_(4))_(2)Mg_(2)(SO_(4))_(3),再分解得到MgSO_(4)。反应遵循化学反应和扩散混合控制机理,其表观活化能为33.02 k J/mol。

(NH_(4))_(2)SO_(4)roasting–water leaching process was studied as a method for improving the utilization efficiency of magnesite.Transformation of the mineral phases during roasting was evaluated by X-ray diffraction(XRD)analysis,combined with thermogravimetry-differential thermal analysis(TG-DTA).The data were compared with the phase transformation of Mg O during roasting using(NH_(4))_(2)SO_(4).The experimental results demonstrated that at a(NH_(4))_(2)SO_(4)/magnesite(Mg O in ore)molar ratio of 1.6:1,roasting temperature of 475°C,and roasting time of 2 h using a particle size of~74μm,the magnesium extraction rate reached a maximum of 98.7%.The phase transformation during roasting could be summarized as follows:Mg CO_(3)was transformed into(NH_(4))_(2)Mg_(2)(SO_(4))_(3),and then decomposed into MgSO_(4).The reaction followed the mixed control mechanism involving chemical reaction control and diffusion control,with an apparent activation energy of 33.02 kJ/mol.