Optimization Of Metal Mine Ventilation System And Economic Analysis Of Deep Mine Refrigeration System

Gold production is of great significance to economic development.In recent years,the demand for gold in various countries has been increasing.As the shallow gold resources are exhausted,deep mine-mining technology has attracted more and more attention.As the mining depth of the mine increases,the ground pressure and the rock temperature increase,the technical difficulties faced in terms of mine lifting,drainage,support,and ventilation also increase.Among them,the problem of thermal hazard is the key to restrict deep mine mining,which directly affects the production efficiency of mines and the safety of personnel and equipment.This article is based on field investigation and testing of a gold mine in Shandong.First,the air flow and cooling characteristics of single-head stope are simulated and analyzed.New evaluation standards:PMV(Predicted Mean Vote),PPD(Predicted Percentage Dissatisfied)and Air Age are proposed and verified in the environmental assessment of the single-headed stope.Then the effects of the Filled-Return air well,the size of air duct section and double air ducts on ventilation are researched.Secondly,the series ventilation model of multiple single-head stopes was simplified and established.The numerical simulation method was used to compare the flow and cooling characteristics of the actual no Filled-Return air well ventilation mode and Filled-Return air well individual return air mode.The Filled-Return air well auxiliary return air mode is proposed according to the research results and is optimized using the mine air curtain.Finally,the temperature of the fresh air in the deep mine may be higher than the set temperature of the environment if ventilation is the only way to control mine temperature,resulting in the failure of the ventilation to achieve the required cooling effect.Therefore,a deep mine cooling system must be established to cool the fresh air to ensure the cooling effect of the underground ventilation.So the underground heat sources have been analyzed and calculated in detail in this article on the basis of actual underground mining and ventilation structure.And the economics of the cooling water transportation system,chilled water transportation system and ice transportation system have been quantitatively calculated and analyzed.The research results show that the PMV and the Air Age criteria can effectively reflect the thermal comfort and air flow characteristics of the single-head stope.One-sided ventilation in the single-head stope will form a severe vortex zone on the side of the duct,resulting in the PMV value and the distribution of Air Age are significantly higher than the other side,which means the thermal comfort and air quality of the air duct side are poor.But the dual ducts heterolateral ventilation can effectively improve this problem.For the tandem ventilation system of the single-head stope,the cooling effect of the no Filled-Return air well ventilation mode is the worst,the Filled-Return air well individual return air mode has the highest resistance,and the ventilation effects of the Filled-Return air well auxiliary return air mode is between the two other modes.The method of adding a mine air curtain can effectively increase the return air volume of the Filling-Return air well.By adjusting the air pressure of the air curtain,the system return air volume and resistance can be adjusted.Under the model studied,the air curtain air pressure is increased from 0 to 500Pa,the return air volume of the Filling-Return air well becomes 3.3 1 times the original,and the system resistance increases to 3.08 times the original.Among the three deep mine refrigeration systems studied,the initial investment of the open cooling water system equipment is the lowest,and the chilled water transportation system has a greater advantage in system power.If the system runs all day,it only takes 283 days to make up the initial investment gap of the cooling water system.The equipment of ice transportation system is complicated and the ice machine COP is too low,resulting in excessive power per unit cooling capacity.Under the given calculation conditions,there is no advantage of ice transportation system in terms of investment or system power.