基于PHREEQC拟合地浸采铀尾液中去除硫酸根离子模拟研究

Simulation Study on Removal of Sulfate Ion in In-situ Leaching Uranium Tail Liquid Based on PHREEQC

对某砂岩型铀矿地下水淡化少试剂地浸采铀浸出液中SO4^2-的去除试验进行数值模拟。对三组溶液(溶液3、溶液4、溶液7)一共进行了7次模拟实验,得到Ca^2+与SO4^2-反应生成石膏沉淀的速率为(4.8~9.4)×10^-9 mol/(cm^2·s)。其中溶液3三组反应与溶液4两组反应的模拟值与实测值几乎一致,溶液7两组反应模拟结果的去除率略低于实测值。当溶质中SO4^2-浓度与模型中三种溶液浓度相近,溶液中加入12g/L,可以确定SO4^2-沉淀速率为(7.2~7.75)×10^-9 mol/(cm^2·s)。CaO溶解在水溶液中会放出一定的热量,不同溶液的饱和指数也有所差异等原因使得模拟结果所得到的沉淀速率不是一个确切值,而是在一个区间值内,但都在同一个数量级内,并且模拟结果与实测结果拟合较好。

SO4^2- removal experiment in lixivium of in-situ leaching of uranium from a sandstone-type uranium mine with less reagents in groundwater desalination was studied by numerical simulation.Three groups of solutions(Solution 3,Solution 4 and Solution 7)were simulated for seven times.Gypsum precipitation rate formed by Ca^2+ reacting with SO4^2- is(4.8-9.4)×10^-9 mol/(cm^2·s).Simulated values of three groups of reactions in Solution 3 and four groups of reactions in Solution 4 are almost the same as measured values.Removal rate of simulated results in Solution 7 is slightly lower than measured values.When SO4^2- concentration in solute is similar to that of three solutions in the model,precipitation rate of SO4^2- in solution can be determined to be(7.2-7.75)×10^-9 mol/(cm^2·s).CaO dissolution in aqueous solution will emit a certain amount of heat,and saturation index of different solutions is also different,which makes precipitation rate obtained by simulation results not an exact value but an interval value,but it is in the same quantity and range,and simulation results are in good agreement with measured results.