Porosity And Permeability Of Uranium Bearing Sandstone In Bayanwula Uranium Deposit Experimental Study On Temporal And Spatial Evolution

Uranium resources are not only strategic material for national defense,but also important material basis for nuclear power development.Based on the national Natural Science Foundation of China（U1967209）Nuclear Technology Innovation Joint Fund project,this paper takes Bayanwula uranium deposit in Erlian Basin,Inner Mongolia as the research base and the uranium ore-bearing bedding rock ore as the research object.The material composition of rock and ore,one-dimensional sandbox acid hydraulic test,uranium leaching test,tracer test and simulation of the interaction between leaching solution and rock and ore were systematically carried out.The research results have important practical significance for the analysis of the main bottleneck problem of blocking ore-bearing layer restricting large uranium producing area in the process of uranium mining.The main conclusions are as follows:（1）the uraniferous sandstone is high in potassium,high in sodium and low in calcium;There is a positive correlation between Ca O and Na₂O,Si O₂and Na₂O,K₂O,Fe O and Si O₂,and a negative correlation between Al₂O₃,Ca O,TFe₂O₃,Mg O and Si O₂.The main minerals in rock ores are quartz,feldspar and clay minerals.Rock ore sample features complex structure,uneven surface;（2）the light intensity of rock ore is positively correlated with the particle size of rock ore,and the light intensity of dry rock ore is stronger than that of wet rock ore.In the acid leaching test,the concentration of Ca²⁺in leaching solution increases first,then decreases and then tends to be stable.With the dissolution of Ca-containing minerals,Ca²⁺and SO₄^2-reach saturation and Ca SO₄precipitation occurs.（3）In the acid uranium leaching test,with the injection of leaching solution,the flow rate of leaching solution decreases from 16.9m/d to 3.27m/d～3.35m/d,indicating that blockage occurs in the rock ore;（4）Hematite,goethite and gypsum are the minerals that precipitate in the process of acid leaching test,which are the main reasons for the decrease of porosity and permeability of rock ores;（5）In the process of acid uranium leaching test,minerals containing K,Na,Ca,Al,Fe,Mg,Si O₂and other minerals in rock ore are dissolved to varying degrees,and minerals containing S are precipitated.（6）The quartz content in the slag sample is less than the original sample,indicating that quartz has been dissolved;The clay minerals（such as illite,kaolinite,halloite,etc.）in the slag samples are larger than the original samples,and the clayification phenomenon of feldspar is obvious and common.The secondary clay minerals are the important factors leading to the clog of rock ore pores and the decrease of the permeability of uranium-bearing sandstone.To sum up,this thesis aimed at uraniferous sandstone porosity and permeability space-time evolution characteristics to carry out a series of indoor experiments,was obtained under the condition of one dimensional seepage,acid leaching process of uranium in uranium time-space evolution characteristics of sandstone,research results for revealing layer containing uranium deposits blocking conditions and mechanism,determine blockage prevention measures,has high scientific value and practical significance.