Study On Weakening Law And Correlation Of Bedrock Strength Of Ion-adsorption Rare Earth Deposits Under Leaching

The bedrock of ionic rare earth deposits as a carrier of rare earth ore bodies has been eroded by the leaching mother liquor throughout the entire in-situ leaching mining period of the rare earth mine and at the end of the leaching period,resulting in weakening of some strength of the bedrock and reducing its effective carrying capacity.In the process of comprehensive management of rare earth mines,changes in the effective bearing capacity of bedrock were often ignored.In response to the above problems,this paper simulates the environment in which the leaching mother liquor erodes the bedrock.The characteristic strength of rock samples was studied by uniaxial compression acoustic emission test,and the microscopic features such as microscopic morpHology and pores of rock samples were analyzed by electron microscope scanning test and nuclear magnetic resonance test.A multi-source information fusion fuzzy grey correlation model of ionic rare earth bedrock strength based on combined weight was established.The model was used to analyze the correlation between the strength of ionic rare earth ore bedrock samples and their influencing factors with different leaching durations.The main results and conclusions of this paper are as follows:(1)The basic pHysical properties of the bedrock rock sample and the ore leaching mother liquor were measured,and it was found that the bedrock rock sample conformed to the pHysical parameters of the granite rock sample,so the test object in this paper is granite.The leaching mother liquor has a pH of 3.392 and is acidic.(2)The peak stress of the rock samples after immersion in the leaching mother liquor decreased.The peak intensity was the smallest when the samples were immersed for 60 days,which was reduced by about 24.32% coMPared to that in the natural state.The peak stress recovered after 90 days of immersion.The peak strain got a rise after 60 days of immersion.(3)It can be seen from the electron microscope scanning test that the microscopic defects such as cracks in the rock samples at the initial stage of immersion continue to develop,and the rock samples corrode most seriously after 60 days of immersion.The NMR test showed that the porosity of the rock samples after immersion increased,and the porosity was the smallest when the samples were immersed for 90 days.This also explains the rebound of peak stress to a certain extent after immersion for 90 days.(4)The cracking strength and damage strength obtained by the three methods were first reduced,then increased and finally stabilized.Both the cracking strength and the damage strength showed a large recovery after soaking for 90 days.The analysis combined with the results of nuclear magnetic resonance and electron microscopy shows that the change of characteristic intensity is caused by the evolution of microscopic structures such as pores and fissures of rock samples.(5)The coefficient of variation coefficient weighting method was introduced to combine the weights of the multi-source information fusion fuzzy gray correlation analysis model,and the multi-source information fusion fuzzy gray correlation model of ionic rare earth bedrock strength based on the combination weight was established.According to the model,the correlation between the three mechanical strengths of the rock sample and the five influencing factors were calculated.The results show that the five influencing factors rank the three macromechanical strength correlations in the order of fractal dimension> macropore> overall porosity> pH of leaching mother liquor> small pore.With regard to the correlation of the three macroscopic mechanical strengths,damage strength> cracking strength> peak strength.(6)The weakening law of the bedrock strength of the ionic rare earth deposit under the effect of leaching erosion was analyzed: the dynamic evolution of the microstructure of the bedrock sample of the ionic rare earth deposit under the erosion of the leaching mother liquor caused the rock sample to crack.The dynamic changes of mechanical properties such as strength,damage strength,peak strength,etc.specifically present the result that the three strengths decrease first,then rebound to a certain extent,and finally fluctuate within a certain range.