Precipitation Crystals Technology And Mechanism Research On Ion-absorbed Rare Earth Ore

At present, NH4HCO3precipitation process has developed mature, and had be widely usedamong the rare earth industry. But there were many problems have not been satisfactorilyresolved. For example, liquor impurity removal process is complex, difficult to control,cleaning effect is not good enough, and precipitation process is easy to generate amorphousprecipitate, resulting in solid-liquid separation difficulties. In this paper, these two problemswere deeper study, and finally get a more efficient process of impurity removal andprecipitation. This will have a significant meaning and guidance in the field of rare earthsprecipitated crystals.Experimental study of rare earth impurities leaching and liquor. Optimum leachingconditions are leaching agent concentration of4%, liquid to solid ratio of0.95, leaching flowrate of1.6ml/min.And the best method for removing impurities is ammonia+QL-01combination, and under the premise of rare loss rate of less than5%, more than96%of Al3+was removed, more than98%of Fe3+was removed. The impurity effect was significantly betterthan conventional impurity processes.To purify the leachate as raw material, preparation of crystal rare earth experiments wasimplemented. Eventually found that: when without the crystal seed, determining theconcentration of0.8~6.5mol/L is appropriate; uniform charging method is more advantageous;precipitate as it was stirred smaller; larger concentration, the smaller the volume of theprecipitate; greater effect of temperature on the precipitation crystallization process, theoptimum temperature about45℃; with increasing aging time, the precipitated crystallineproduct is increasingly apparent. When join the crystal seed, crystallization rate faster and canget better crystals. Further, when bicarbonate magnetized, crystalline product particles is greater,and the crystal characteristic crystals more obvious.Since the effect of technology trials, the Reaction Mechanism of QL-01and Al3+and thecrystallization mechanism of rare earth carbonate have been studied. Eventually found that:QL-01and Al3+reaction produce a flocculent precipitate and in the case of a low concentrationAl3+react more thoroughly. And the crystallization process: generated by the firstone-dimensional vertical growth of acicular fine crystals, then started to the two-dimensionallateral growth on the basis of acicular fine crystals; There exists a seed crystal growth is morethree-dimensional, crystal growth has been transformed by a two-dimensional to three-dimensional growth direction or more. Ammonium bicarbonate after magnetization,changed the direction of bicarbonate of magnetic and hydrogen bonds...