Separation and purification of Yb_(2)O_(3) by ion exchange chromatography and preparation of ultra-high purity Yb_(2)O_(3)

Ultra-high purity Yb_(2)O_(3) is the critical material of many high-tech materials such as laser glass and fiber,in which impurities seriously affect the laser color quality,intensity and power.In order to reduce the influence of impurities on the properties of laser materials,the purification process of Yb_(2)O_(3) was studied by comparing two kinds of resins(RT-1 and RS-1)using improved ion-exchange chromatography(IEC)method.In this study,through the synergistic improvement of resin structure and eluting system,the environmental pollution caused by ammonia water in the traditional IEC method was reduced,and the requirements of high temperature and pressure were cut.The ion exchange behavior and impurity removal mechanism in the resin column during the loading and eluting process were compared and analyzed.The experimental results show that RS-1 resin is all superior to RT-1resin in elements selectivity,ion exchange capacity and impurities removal rate.After separation and purification by IEC with RS-1 resin,the total removal rate of rare earth impurities was 77.59%and that of non-rare earth impurities was 95.86%when Yb recovery was more than 70%,both higher than that of RT-1 resin(73.26%and 83.18%).This indicates that the improved IEC method is very effective in separating and removing different metal impurities from Yb_(2)O_(3).The pilot test results of IEC method separating and purifying Yb_(2)O_(3) with RS-1 resin show that the purity of Yb_(2)O_(3) can be increased from 99.9929%to 99.9997%by IEC method.It has exhibited huge potential of preparing ultra-high purity Yb_(2)O_(3),especially the deep removal of non-rare earth impurities.

A new method for direct synthesis of Li2CO3 powders by membrane electrolysis

A new method for the direct synthesis of Li2CO3 powders by membrane electrolysis from LiC1 solution is demonstrated in this paper, where a novel electrolysis system combining ventilation, agitation and loop filtration functions was reported. The aim of this work is to explore the effect of the starting concentration of LiC1 on the phase and micromorphology of Li2CO3 crystals and thereafter to explore the mechanism of crystallization and grain growth law. Scanning electron microscopy （SEM） images indicate that the particles become irregular polycrystalline from well-defined flower-like and the micro-crystals change from lamellar to needle-like and subsequently to smaller globular granules, and the surface of the crystals becomes smooth with LiC1 concentration increasing from 50 to 400 g.L^-3. The crystalline phases of the different samples were characterized using powder X-ray diffraction （XRD） and the results prove that pure LiaCO3 crystals can be obtained in a single step by the electrolysis method. The particle size distributions show that both volume mean crystal sizes and the full width at half maximum （FWHM） decrease when the starting LiC1 concentration increases from 50 to 300 g.L 3 and also decreases from 400 to 300 g-L^-3.