Study On The Technology Of Calcification Decomposition And Flotation Separation Of Bastnaesite Concentrates

Mianning rare earth ore deposits in Sichuan are a kind of typical bastnaesite type mineral resources.80%of the rare earth oxides in the ores concentrate in bastnaesite.The currently widely used process is composed of oxidizing roasting,prior leaching of non-cerium rare earth and alkali decomposition.In production it's difficult to deal with wastewater containing fluorine leading serious environmental pollution and waste of resources.High agent and energy consumption also exist.In order to solve these problems and develop clean metallurgy process that can efficiently recycle valuable resources like rare earth and fluorine,this paper puts forward a novel process mainly consist of calcification roasting decomposition and flotation separation.The research contents and rusults are as follows:(1)The influence factors of bastnaesite calcification roasting process were studied and the optimal process conditions were obtained:the quantity of Ca(OH)2 is 20%,the roasting temperature is 650? and the time is 60min.The decomposition rate of bastnaesite concentrate can be 98.84%.It is mainly rare earth oxide,fluorite and calcium oxide in roasted ore.Rare earth oxides can be determined mainly in]arge particles of>48?m calcium fluoride distribute evenly in different size particles.At the same time,compared with that in concentrates,the liberation degree of rare earth oxides and calcium fluorides in roasted ores are much higher.(2)Study on the thermal decomposition process and mechanism of bastnaesite calcification roasting has been done via TG-DTA and XRD method.The results show that the decomposition of rare earth minerals can be effectively promoted by adding Ca(OH)2.Rare earth oxides are formed through the reaction between the thermal decomposition products of bastnaesite and Ca(OH)2.At the same time,the fluorine in the ore can be fixed in the roasted products in the form of calcium fluoride instead of escaping as gases.(3)In the way of single ore flotation experiment,the flotation laws of fluorite and rare earth oxides in three typical collector systems were obtained,laying the foundations for the following separation of fluorite and rare earth oxides.(4)The action mechanisms between agents and minerals were studied through fourier transform infrared spectroscopy.The results show that normally sodium oleate,sodium dodecyl sulfate and dodecyl amine hydrochloride can adsorb fluorite and REO;water glass would adsorb in the surface of fluorite and restrain the interaction between collectors and minerals while it had no obvious effect on rare earth oxides.The above results prove that it is practicable to accomplish the comprehensive utilization of bastnaesite resources in the way of calcification roasting and flotation separation.This method is not only environmentally friendly,but also can effectively recycle rare earth and fluorine resources.It is of great significance for the clean and efficient utilization of rare earth mineral resources.