Calculation moisture content distribution around injection hole during in-situ leaching process of ion-adsorption rare earth mines

Ponding in injection hole will generate pressure head in soil surface. Considering the transfer of the pressure head through the soil, a basic equation for one-dimensional vertical infiltration under ponding is developed. The measured saturated hydraulic conductivity is regarded to be equivalent to that of one-dimensional infiltration, and the distribution rules of moisture content along the vertical direction of the injection hole of the hole bottem is calculated by the basic equation for one-dimensional vertical infiltration under ponding. Assuming that the moisture content increment is equal in each wetting front which is formed during infiltration process, and according to that the cumulative liquid injection is equal to the moisture increment in the wetted region, each wetting front is obtained. Considering with the moisture content distribution along the vertical direction of the injection hole of the hole bottom, the moisture content distribution in the wetted region is determined. A smooth ore block in Zudong rare earth mine in China is chosen to perform single-hole injection tests, and 4 measuring points are arranged around the injection hole. During the infiltration process, the moisture contents at measuring points are recorded by FDS-100 moisture sensors. By comparing the values calculated by the proposed model with the test ones, it is found that the correlation coefficient between the calculated values and the requirements is satisfactory. During the infiltration process, the moisture content distribution in the wetted region is calculated accurately by the established model.