Numerical Simulation Of Phase-change Behavior Of Ice-added Filling Materials And Stope Cooling

Since the last century,the exploitation and utilization of worldwide mineral resources has reached an unprecedented intensity and scale in human history.With the continuous extension of mineral resources exploitation to the deep strata,the problems of high ground stress and high ground temperature are becoming increasingly prominent,the backfill mining technology is an effective measure to alleviate the problem of high ground stress in deep mining.Based on the filling mining technology,this paper proposes to add a certain proportion of ice particles to the filling slurry to decrease the temperature of stope,so as to alleviate the problem of thermal hazard in the deep mine.This article takes the ice-added filling materials in the goaf area as the main research body,based on the basic theories of heat exchange between high-temperature heat source and wind flow,thermal conductivity of surrounding rock,and heat production of cement,etc.,the numerical simulation is carried out on the heat transfer problem of the ice-added filling slurry and the surrounding rock?the stope in the filling area,and under different porosity and different ice-water ratio,the change of liquid phase rate,the surface mean temperature and average temperature of filling body surface near stope are analyzed in the melting process of ice-added filling materials.The results show:(1)When the ice-water ratio is 1:1,during the melting process,Because of the different porosity,the time nodes when ice becomes water are also different,which also indicates that the size of the porosity directly changes the melting rate.When the porosity is 0.22,the liquid state is generated on the 1.8th day of the melting process;when the porosity is 0.32,the liquid state is generated on the 2.8 days of the melting process;when the porosity is 0.42,the liquid state is in the 3.4th of the melting process days produce;when the porosity is 0.52,the liquid state occurs on the fourth day of the melting process.(2)When the ice-water ratio is 1:1,the time required for the complete melting of ice increases with the increase of porosity.When the porosity was 0.22,0.32,0.42,and 0.52,respectively,the time required for the complete melting was 9 days,14 days,17 days,and 22 days,respectively.In the melting process,the change trend of the liquid-phase rate is basically the same,and it changes linearly with time.During the melting process,the average temperature of the entire surface of the filling body changes more than the average temperature of the upper interface near the stope,and the temperature rises continuously as the melt proceeds.(3)When the porosity is 0.32,the melting process of the ice-added filling materials is numerically simulated under the conditions of water-ice ratio of 1:1 and 3:7,respectively.When the ice-added filling materials continuously melts,the ratio of liquid to the filling body is linearly related to the time.The ice-water ratio is different,and the melting time is also different.When the porosity is 0.32 and the water-ice ratio is 1:1,the total melting time of ice in the ice-added filling body is 14 days;when the water-ice ratio is 3:7,the melting time is 17 days.During the melting process,the average surface temperature of the entire surface of the filling body and the average temperature of the upper interface near the stope increase continuously,but the temperature rise of the upper interface is slower than the average temperature of the surface.At the end of melting,their rate of change has the same tendency.As the main body of filling mining technology and synergistic cooling in stope,the filling body cemented by ice-added filling materials should have good mechanical properties,meet the requirement of filling strength,It is also required that the ice particles added in the filling slurry can decrease the temperature of the stope well in the process of melting.The effects of porosity and ice-water ratio on the melting rate and the melting time of ice particles can provide the basic data for the analysis of the cooling efficiency of ice-added filling materials,it also lays a good foundation for the application of filling mining and stope cooling technology.