砂岩铀矿围岩中性条件下对铀的吸附试验

砂岩型铀矿地浸采铀体系中,溶解铀在水岩界面发生的吸附作用对铀的浸出造成一定影响。为研究CO_2+O_2中性地浸条件下含矿层砂岩介质对溶解铀的吸附特征,采用取自新疆蒙其古尔铀矿床围岩和含铀浸出液,在实验室开展了不同粒径介质和不同固液比的吸附试验。结果表明,不同粒径介质对铀的平衡吸附量介于11.62～20.28mg/g,铀的平衡吸附量以及吸附率与粒径负相关;不同液固比试验条件的平衡吸附量介于10.07～18.23mg/g,铀的平衡吸附量与液固比正相关,铀的吸附率则与液固比负相关。围岩对铀的吸附动力学特征符合粒内扩散模型。试验结果可以为地浸采铀溶质运移模拟过程中吸附模型及其参数的确定提供依据。

Experimental Study on Adsorption of Uranium by Surrounding Rock of Sandstone Uranium Deposit under Neutral Conditions

In water-rock system of in-situ leaching of sandstone-type uranium deposit, adsorption of dissolved uranium at solid-liquid interface has effect on uranium migration. In order to investigate adsorption characteristics of dissolved uranium by ore-bearing layer sandstone medium under CO2+O2 neutral leaching condition, adsorption tests with different particle size media and different ratio of solid to liquid (L/S) were conducted in laboratory with uranium bearing leaching solution and surrounding rock of uranium deposit in Mengqiguer, Xinjiang. The results show that equilibrium concentration of adsorbed uranium on different sizes of rocks is between 11.62~20.28 mg/g. Both equilibrium adsorbed concentration and adsorption rate of uranium inversely correlate with particle size. Equilibrium adsorbed concentration of uranium under different L/S condition is between 10.07~18.23 mg/g, and equilibrium adsorbed concentration of uranium positively correlate with L/S, but adsorption rate of uranium negatively correlate with L/S. Adsorption kinetic characteristics of uranium by rocks is consistent with intragranular diffusion mode. The results can provide a basis for determination of adsorption model and calibration of parameters in simulation process of in-situ leaching uranium solute transport.