Experimental Study On The Influence Range Of Single-hole In In-situ Leaching

At present,we are promoting to use in-situ leaching mining technology to exploit ionic rare earth resources,the mining process has basically reached the expected economic effect,but due to the actual situation of each mining complex,and there is no uniform standard,many processes are based on experience exploitation,a lot of problems also appeared in the process of mining,such as unreasonable layout of mesh the leaching rate of rare earth,resulting in two times of reperfusion phenomenon.So it is of great significance to standardize filling process and reduce the waste of resources by researching the different injection strength of single hole infiltration test and ore and tailings grade distribution.This paper is aimed at the research and analysis of some problems found in the research on the injection technology of an ionic rare earth mine in Longnan County,Ganzhou City,three field experiments were carried out to analyze the influence of single hole in the in-situ leaching.The first one is a single hole liquid infiltration test,we are able to get the saturation cloud of the first 1-10 days by monitoring the change of water content around the injection hole with 5 different injection intensity,according to the cloud chart we can analyze the influence of single hole;The second one is a tracer test with single hole injection,the basic assumptions of the model for calculating the influence range of single hole injection are put forward based on the experimental results,we can establish the calculation model of single hole influence range on the basis of the amount of water injected into the liquid hole is equal to the increment of water content in the range of injection;The third is the field sampling test,we can understand the impact of the injection hole network parameters on in-situ leaching by taking some different positions of tailing in the field to test the distribution.Through the above analysis,the main conclusions are as follows:(1)calculation model of single hole influence is established,we obtained 5 different injection strength of the steady-state calculation,compared with the field test value,the maximum error is 16.7%,the result can meet the engineering requirements,and with the increasing of injection strength,the error also decreases.(2)The nonuniformity of volume water content around the injection hole is very significant,the single hole injection strength was in a nonlinear relation with the liquid height,single hole influence range has an exponential relationship with the injection time,the influence range of high saturation greater than 90% varies slowly with time,during the first 4 days of the injection,the influence range of saturation less than 80% changes very fast with time and gradually stabilized;The single hole injection reach the steady state in tenth days.(3)the ore grade along the depth direction is similar to "P" shape,the surface of ore grade is high,up to 1 per thousand,the rare earth grade decreases rapidly with the depth increases,and gradually stabilized.The surface slope has a certain influence on the leaching rate,with the increase of slope,the leaching rate decreases when we take the same injection hole network parameters.(4)With the increase of the distance from the injection hole,the rare earth grade increases and the leaching rate decreases,when the injection hole spacing is more than 4.0m,with the increasing of depth,the ore grade is high and large fluctuation,the leaching rate of resources also become low;when the injection hole spacing is less than 3.0m,with the increasing of depth,ore grade decreases rapidly,when the depth is larger than 2.0m,ore grade is stable;For the type of Longnan rare earth ore,injection hole spacing should not exceed 3.0m.(5)The leaching rate of light rare earth elements in the leaching process is lower than the average leaching rate of rare earth elements,while the leaching rate of heavy rare earth elements is higher than that of rare earth elements.