Study on CaO decomposing bastnaesite in assistant of NaCl-CaCl2

Now in process of bastnaesite decomposed, fluorine gives out as gas phase. Therefore, fluorine resource is wasted, and the environment is also polluted. In order to find new cleaning metallurgy method, the decomposition reactions of heading mineral roasting by CaO-NaCl-CaCl2 are studied by means of TG-DTA and XRD methods. The relationship between decomposition ratio and four factors is studied by the quadratic regression orthogonal analysis, and then the regression equation is obtained. The optimum process conditions are obtained as follows: roasting temperature: 700℃, CaO addition: 15%, NaCl-CaCl2 addition: 10%, roasting time: 60min, the decomposition ratio: 92.14%. Through analysis, because CaO is added, fluorine exists in roasting products as CaF2 solid, and the formation of gas phase fluorine is restrained. Thus it is shown that the method is a cleaning metallurgy technology in this thesis.