Experimental Study On Pore Size Change And Seepage Law Of In-situ Leaching Of Ionic Rare Earth

Now,we use in-situ leaching mining technology to exploit ionic rare earth resources.This caused serious geological disasters like landslide and so on,because of they mainly depend on experience to exploit it.So it is of great significance to research the seepage law of leaching ore fluid in mine and the stability of the slope in the whole injection liquid cycle for the safety of the ionic rare earth mining.The paper proposes a method to test effective pore size and distribution of soil parameters at first,and verifies it through column leaching experiment in the laboratory,analyzing the pore size variation law during mineral leaching.According to the bore diameter's change law of the ore body obtained through field tests,the author analyzed seepage law in in-situ leaching,thereby to judge the stability of slope.Field trials are mainly divided into three: the first is injection volume and collecting liquid volume monitoring test in the in-situ leaching,to determine solution recovery rate and steady seepage period of the test mine;the second is monitoring test of the variation of soil moisture to judge capillary water height because of the capillary,the height of the saturated seepage vertebral formed in the periphery of the liquid injection hole,and analyze the relationship between the volumetric water content increment and hydraulic gradient of soil;the third is the slope deformation analysis test to analyze slope deformation in the horizontal and vertical directions.(1)When the soil sample porosity is 44.4%,relative to the remolded screening sample that particle size range from 0.075 mm to 0.09 mm,the average effective aperture and effective porosity of the remolded crude ore sample are 1.14 times and 1.90 times respectively,but the pore size distribution parameters of them are basically same.So we can judge that aperture distribution does not change in the process of in-situ leaching mining.(2)The solution recovery of mining experiment was 74.39%,then it achieved a stable flow in first 70 days of the fluid injection.(3)When pouring strength is 0.26m3 / d and liquid injection depth is about 3.6m at test area at mountaintop,capillary water rise height is about 2m.The position of the saturated seepage vertebral formed in the periphery of the liquid injection hole is between 3.8m-4.6m,that is to say,the height of the vertebral is 0.8m.(4)In steady seepage,a certain depth with a gap of 0.4m below depth of the fluid injection,water potential gradient between the two is 4kpa,soil volumetric water content increment of the depth is 15% the same as the depth of the fluid injection,a certain depth with a gap of 0.8m above depth of the fluid injection,water potential gradient between the two is 7kpa,soil volumetric water content increment of the depth is 5% one third of the fluid injection(5)Settlement of the peak under its own weight occurred in the perfusion of 60-80 days,while mountainside settlement under its own weight occurred in the perfusion of 60-90 days.In the valley,the soil located at the mountainside shows a tendency toward the foot of the mine,and the slope soil pressure according to Rankine's earth pressure calculation.