“CO_(2)+O_(2)”地浸采铀含矿层防堵技术研究

Preventing Blocking Technology of Ore-bearing Layers in“CO_(2)+O_(2)”In-situ Leaching of Uranium

某试验采区运行约200 d,注液井注液压力提高至1.65 MPa,平均注液量下降了51.87%,周边含矿层堵塞严重。计算表明,当由天然流场条件转变为抽注浸出流场条件时,地下水流速可快速提高几十、上百倍,水力冲刷作用是抽液井周边含矿层中碎屑析出的动力学条件;浸出液经地表过滤、树脂床吸附后,尾液中含有的矿物碎屑和化学沉淀物在注液井周边含矿层中再沉积,是导致含矿层堵塞的直接原因;矿层堵塞以机械堵塞为主,化学堵塞为辅。根据含矿层最大孔喉直径的研究结果,结合井下电视观察以及浸出液、洗井水中颗粒物粒度、洗井水沉降干渣化学组成分析,确定矿物碎屑主要是黏土粉砂粒级碎屑,化学沉淀物主要有CaCO_(3)、MgCO_(3)、Fe(OH)_(3)及少量FeCO_(3)。以“防堵”为切入点,增设了水力旋流器,耦合“自然沉降—旋流分离—机械筛滤”地表固液分离系统,取得了明显防堵效果。

Blockage of ore bearing layers is the most common technical problem in in-situ leaching of uranium.A certain experimental mining area has been operating for about 200 days,and the injection pressure of the injection well has increased to 1.65 MPa,and the average injection flow rate has decreased by 51.87%,and serious blockage has occurred in the surrounding ore-bearing layers.The calculation shows that when the natural flow field conditions are transformed into the leaching flow field conditions,the groundwater flow velocity can be rapidly increased by tens to hundreds of times.Hydraulic erosion is the dynamic condition for the migration and precipitation of debris in the ore-bearing layers around the pumping well.The mineral debris and chemical precipitation carried in the leaching solution,which are retained in the tail liquid after surface filtration and resin bed adsorption,are re-deposited and accumulated in the ore bearing layer around the injection well,which is the direct cause of its blockage.During the research period,mechanical blockage was the main factor,accompanied by chemical precipitation blockage.Based on the research results of the maximum pore throat diameter of previous ore bearing layers,combined with underground television observation,the particle size of the leaching solution,well washing water,and the chemical composition analysis of the settling dry residue of the well washing water,it is determined that the mineral debris is mainly clay powder sand particle level debris,and the chemical precipitation is mainly CaCO_(3),MgCO_(3),Fe(OH)_(3),with a small amount of FeCO_(3).For this reason,with the goal of“preventing blocking”,a hydrocyclone separator has been added.The surface solid-liquid separation system coupled with“natural sedimentation-hydrocyclone separation-mechanical screening”has achieved obvious results,which is expected to be popularized and applied after further research.