离子型稀土矿体孔径分布及其渗透性变化

Pore Size Distribution and Permeability Variation of Ion-adsorption Rare-earth Ore Sample

以江西龙南典型的离子型稀土矿为研究对象,对原矿和5种孔隙比重塑矿开展了现场和室内土-水特征曲线和饱和渗透系数测试试验。基于土-水特征拟合曲线,计算了矿体孔径分布和非饱和渗透系数。结果发现:孔隙比0.92的原矿单位质量矿体累积孔隙总体积为0.234 5 cm^3/g,大孔隙(r≥5μm)、中孔隙(2μm≤r≤5μm)和小孔隙(r≤2μm)体积分别占孔隙总体积的58%、15%和27%,渗透系数为2.0×10^(-5)m·s^(-1);保持原矿孔隙比重塑后,小孔隙体积增加约3.0%,渗透系数为1.2×10^(-5)m·s^(-1),表明相同孔隙比的原矿和重塑矿在孔径分布上有明显差异,原矿存在较多大孔隙,重塑后大孔隙分裂成多个小孔隙,矿体通透性变差,渗透系数变小。而重塑为孔隙比0.97的矿样,小孔隙体积减少约1.0%,渗透系数为1.9×10^(-5)m·s^(-1),孔径分布和渗透性基本达到原矿状态,采用该孔隙比状态的重塑矿样模拟龙南类型天然矿体进行浸析试验效果更好。

Soil-water characteristic curve and saturated infiltration coefficient tests in field and lab were carried on typical ion-adsorption rare-earth ore in Longnan of Jiangxi,the pore size distribution and unsaturated infiltration coefficient of undisturbed ore body and remoulded ore body with 5 different void ratio were calculated based on soilwater characteristic fitting curve,the experimental results have shown that cumulative total pore volume of undisturbed ore body with 0. 92 void ratio is 0. 234 5 cm^3/ g,volume of large pores,medium pores and small pores account for 58%,15% and 27% respectively,saturated infiltration coefficient is 2. 0 × 10^-5m·s^-1refiguration remained the same void ratio increased the volume of small pores by 3. 0%,saturated infiltration coefficient is 1. 2 ×10^-5m·s^-1. It indicated that undisturbed and remoulded ore body have obvious differences in pore size distribution. There are more large pores in undisturbed ore body,refiguration changed large pores into multiple small pores and made infiltration coefficient lower. Refiguration remained 0. 97 void ratio reduced the volume of small pores by1. 0%,saturated infiltration coefficient is 1. 9 × 10^-5m ·s^-1,pore size distribution and permeability reach the original state,it should be remoulded as ore samples with 0. 97 void ratio,while column leaching tests are used to simulate Natural ore body Leaching.