The. Bastnaesite Treatment Process

Reviewing the issued processes about Bastnaesite in the past decades, it is believed that the "Oxidative calcinations-dilute sulfuric acid leaching-extraction" process, which includes the following three steps: oxidative calcination in the air and leaching with dilute sulfuric acid and finally extracting and separating Cerium from the other Lanthanide, is the best method to recover Rare Earth from Bastnaesite. But it is not so consummate and still has some problems urgently need to be solved.The reason of the formation of the third phase in the process of extracting cerium from the Rare Earth Sulfate Solution containing of fluorine was investigated in this paper. The dominant reason is the reduction of the diluent. Taking the self-made S-solvent as diluent can decrease the reductive effect of diluent and avoid forming thirdphase--which couldn't be resolved before. The reductive reaction kinetics in thecommon kerosene and SHELLSOL D70 was studied. It shows that their reactive order is approximately zero. Increasing the reaction temperature can speed up the reaction equilibrium to a new level.Extraction mechanism of eerie from the sulfuric acid solution with different initial ratio of fluoric vs. eerie ion by the P507 diluted in inert diluent was researched by the Slope Method and Saturated Solution Method in this paper. It shows that extraction is cation exchange mechanism but the extracted complexes are different with the different initial ratio of fluoric vs. eerie ion. There is not any evidence showing that the SO42- takes part in the extraction reaction. The reactive entropy and the reactive enthalpy at different temperature were calculated when the ratio of fluoric vs. eerie ions equal to 2. It shows that the extraction reaction is the exothermic reaction and increase the system temperature is not favorable to eerie extraction.The optimal extraction operational condition obtained in this paper shows that the extractant concentration of 1.0-1.2 mol-L"' P507 diluted in self-made S-solvent, eerie ion concentration in aqueous phase is less than 55g-L-1 with acidity about 1.0 mol-L-1, counter-current with current ratio of 1:1, mixing time of two phase is less than 10 minutes. More than 98% eerie ion along with all of the thorium and part offerric ion in initial feed enter into organic phase in extraction.and the concentration of eerie in organic is up to 52g-L-1. with the 99% purity vs. the other Rare Earth. The phase separation is easy at the mentioned extraction conditions and the used circularly extractant still possesses good extractive performance.New method to re-extract the cerium from the fluorine-bearing eerie-loaded organic phase were put forward in this paper. That is the precipitation stripping associating with coordinative (named as PAC method in shortened). And the influence of the opertation condition to the effect of stripping had been obtain. The kinetics research of stripping in PAC system was carried out in a Lewis cell in a constant temperature bath. The result shows that the reaction speed never depends on the agitation rate when the agitation rate up to 600 rpm. It was obtained from kinetics research that the rate-controlling step is the formation of the intermediate complex. The active energy is about 25.4616 kJ-mol-1.