某砂岩铀矿酸法地浸溶质运移与酸化进程分析

为分析某砂岩铀矿酸法地浸试验初期的酸化进程,对与地浸水岩作用密切相关的SO42-、H+、Ca2+、Mg2+、Fe2+和Fe3+等溶质离子运移特征进行了研究。结果表明,下注溶液最快8d抵达抽液孔,40d形成由注液控制的稳定渗流场;H+在水岩作用过程中被部分消耗,其运移羽前沿扩散至抽液孔的时间晚于SO42-离子13d,由H+溶蚀出来的Ca2+、Mg2+则与SO42-同步运移;66d地浸流场实现H+的补给与消耗平衡并形成稳定的浸铀化学场,但需进一步增加注液酸度以达到酸化要求。Fe2+、Fe3+的运移受H+的控制和氧化还原作用的影响,运移与H+基本同步。持续增高的SO42-导致大部分时间内硫酸钙处于过饱和状态,引起浸出液Ca2+浓度和抽液流量的下降。

Analysis of Solute Transportation and Acidification Process during In-situ Acid Leaching of Sandstone Uranium Ore

In order to investigate acidification process during acid leaching test of sandstone uranium ore, the transportation characteristics of solute ions, such as SO42-, H , Ca2 , Mg2 , Fe2 and Fe3 , which are closely related with water-rock interaction of in-situ uranium leaching, were analyzed. The results show in case of SO42-, it takes 8 days for the earliest leaching solution to reach extraction well, and 40 days to form a stable flow field by leaching solution. Ca2 and Mg2 move synchronously with SO42-. Retarded by water-rock interaction, the forefront of H plume reaches extraction well 13 days later than SO42-, and it takes 66 days to stablish balance between supply and consumption of H , in other words, formation of stable geochemical field for uranium leaching. But a further increase of acidity is still necessary to meet acidification requirements when the stable geochemical field is just built. The transportation process of Fe2 and Fe3 are controlled by H and affected by oxidation-reduction reaction, resulting in synchronous transportation of Fe2 and Fe3 with H . Gypsum remains saturated most of the time during leaching process due to high concentration of SO42- and Ca2 , and chemical blockage caused by gypsum precipitation is also conformed by drop of Ca2 concentration and extraction flux.