鄂尔多斯某砂岩铀矿试验开采过程中地下水流场时空特征

Spatial and Temporal Characteristics of Groundwater Flow Field during Experimental Mining of a Sandstone Uranium Deposit in Ordos

砂岩型铀矿原地浸出过程中,需要向含矿含水层注入溶浸液,抽取含铀地下水,创造一个人工局部流场。该流场控制溶浸液迁移和溶浸范围,因此掌握地下水流场特征有利于地浸采铀井场工艺调控。以鄂尔多斯盆地某地浸铀矿山一个试验开采区为例,分析80口生产井工作8年的地下水流场的时空特征,可以得出:1)在研究区中,30个抽注单元抽液流量总体上约等于注液流量,抽注基本平衡。2)C8-1单元抽水能力最大,水位最低。研究区内水位在1186~1344 m,水流方向主要是由注水井流向相邻抽水井。3)C7-10单元抽井与左上角注井井距过大,造成抽注井之间出现溶浸死角。4)如果各抽注单元流量均衡,各抽注井距相差不大,抽注单元易形成流速适中的流场,溶浸死角较小;如果井场中各井抽或注流量差异大,易形成溶浸死角,且不合理的井距会增加溶浸死角的范围。

During the in-situ leaching process of sandstone type uranium deposits,it is necessary to inject leaching solution into the ore-bearing aquifer and extract uranium-containing groundwater to create an artificial local flow field.This flow field controls the migration of leaching agents and the leaching range,so understanding the characteristics of the underground flow field is beneficial for the process control of uranium in-situ leaching wellfields.Taking an experimental mining area of a uranium in-situ leaching mine in Ordos Basin as an example,the spatial and temporal characteristics of the underground water flow field of 80 production wells operating for 8 years were analyzed.The following conclusions were drawn:1)In the study area,the extraction flow rate of 30 extraction units is approximately equal to the injection flow rate in general,and the extraction and injection is basically balanced.2)C8-1 unit has the highest extraction capacity and the lowest water level.The water level in the study area ranges from 1186 to 1344 meters,and the water flow direction is mainly from injection well to adjacent extraction well.3)The distance between unit C7-10 extraction well and injection well in the upper left corner is too large,resulting in a leaching dead zones between extraction wells.4)If the flow rate of each extraction unit is balanced and the distance between each extraction well is similar,the extraction unit is easy to form a moderate flow rate field and smaller leaching dead zones.However,if there is a large difference in the extraction or injection flow rate of each well in the well site,it is easy to form leaching dead zones,and unreasonable well spacing will increase the range of leaching dead zones.