Xu Yuanlai

Column leaching process of rare earth and aluminum from weathered crust elution-deposited rare earth ore with ammonium salts

In order to better understand the leaching process of rare earth (RE) and aluminum (Al) from the weathered crust elution-deposited RE ore, the mass transfer of RE and Al in column leaching was investigated using the chromatographic plate theory. The results show that a higher initial ammonium concentration in a certain range can enhance the mass transfer process. pH of leaching agent in the range of 2 to 8 almost has no effect on the mass transfer efficiency of RE, but plays a positive role in the mass transfer efficiency of Al under strong acidic condition (pH<4). There is an optimum flow rate that makes the highest mass transfer efficiency. The optimum leaching condition of RE is the leaching agent pH of 4–8, ammonium concentration of 0.4 mol/L and flow rate of 0.5 mL/min. The mass transfer efficiencies of RE and Al both follow the order: (NH4)2SO4

Effect of HNO 3 concentration on a novel silica-based adsorbent for separating Pd(II) from simulated high level liquid waste

A new kind of silica-based (Creau2009+u2009TODGA)/SiO2-P adsorbent with high selectivity adsorption for palladium (Pd) was synthesized to examined the applicability for partitioning process of high level liquid waste (HLLW). Adsorption behavior of Pd(II) towards (Creau2009+u2009TODGA)/SiO2-P adsorbent and stability of adsorbent against HNO3 solution were investigated by batch method. The degradation parts of (Creau2009+u2009TODGA)/SiO2-P dissolved in liquid phase were estimated by total organic carbon (TOC) analyzer. (Creau2009+u2009TODGA)/SiO2-P adsorbent showed good selectivity adsorption for Pd(II) and reached equilibrium within 24 hr. The adsorption ability of (Creau2009+u2009TODGA)/SiO2-P for Pd(II) and the content of TOC leaked decreased with the increasing of HNO3 concentration. In 3u2009M HNO3, the average of Kd values were 85.03u2009cm3/g and 26.10u2009cm3/g after contact time one to 28 days at 298u2009K and 323u2009K, respectively. While the content of TOC leaked from the adsorbent after 28 days were 1095 ppm (298u2009K) and 2989 ppm (323u2009K), respectively. Therefore, the adsorbent showed good stability at 298u2009K after contact with nitric acid for a long time. All results indicated (Creau2009+u2009TODGA)/SiO2-P can be proposed as an applicable and efficient absorbent for separation of Pd(II) in 3u2009M HNO3 at 298u2009K.