Study On Modification Law Of Skarn In Qianchang Copper-iron Ore In Anhui Province

The geological conditions of the mining roadway in Qianchang copperite mine in Anhui Province are complicated.The rocks on the top and floor of the ore body are mostly skarn.The joints and fissuresin the surrounding rock of the ore body are developed,and the surface is soft and broken.There are some problems in skarn rock roadway,such as severe surface pressure,floor heave deformation,serious sheet top phenomenon,large overall deformation of roadway and high support difficulty.The support rate of roadway is above 90%.In particular,the continuous expansion of skarn roadway after water often squeezes the rockbolt and shotcrete layer,resulting in the rupture of the traditional rockbolt and shotcrete layer support,and the roadway often needs to be repaired once every six months or even three months,resulting in high support cost and seriously hinders the production progress.This paper is based on the research background of skarn tunnel support in Qianchang copperite mine in Anhui Province,and studied the main factors affecting the expansion characteristics of skarn,and combined with the research status of soft rock modification,explored a new method for the expansion modification of skarn,it provides a new way to solve the problem of expansive skarn tunnel support.Mainly carried out the following research work:(1)Taking typical skarn samples in skarn tunnel of Qianchang copperite mine in Anhui Province as the main test object of this paper,the physical and mechanical parameters of skarn samples were measured,including density,natural moisture content,saturated water absorption,lateral confined expansibility and point load strength.(2)By analyzing the mineral composition and swelling mineral content in skarn,the water absorption expansion rate under lateral constraint was measured,and the degradation mechanism of water absorption expansion was studied.According to the mechanism of expansion and deformation of skarn and the type of expansion minerals,the relationship between the content of expansion minerals in skarn and its maximum expansion and deformation is established.(3)Firstly,the chlorite in skarn samples was investigated and the optimal modification scheme was found to provide theoretical support for skarn modification.Next,the lateral confined load-free expansion rate of skarn samples was studied under four conditions:unmodified skarn samples,clay stabilizer modified skarn samples,organic silicon modified skarn samples and composite modified skarn samples,to explore the relationship between skarn modification method and its modification effect.(4)Based on the engineering practice,the law of free water infiltration and diffusion of skarn was studied.Based on the research results of skarn modification,the supporting countermeasures of skarn roadway were proposed to provide technical support for the field application;The expansion modification mechanism of skarn was analyzed by XRD,infrared spectroscopy and Zeta potential difference,which provided theoretical basis for further popularization and application of modified materials.