Research On The Causes And Prevention Measures Of Fog In A Mine In Yunnan In Winte

The fog that appears in the winter of an underground metal mine in Yunnan Province,damages the health of the staff,corrodes the equipment and facilities,reduces the visibility of the environment,interferes the sight of the staff,and becomes a major safety hazard.Relying on the ventilation system optimization project of an underground metal mine in Yunnan Province,this paper investigates the fog situation on site,detects the air parameters in the shaft,calculates the wet air state parameters in the mine through on-site measurement,calculates water separation into fog in each fogging shaft according to the thermodynamic principle,constructs three mathematical models for the water separation into fog analysis in the mine fog shaft.According to the optimal mathematical model,a software is designed to calculate the water separation into fog in the underground mine in the plateau environment,and the fuzzy comprehensive evaluation method is used to evaluate the safety risk of the mine’s fogging shaft,and puts forward corresponding protective measures.This paper makes a supplement to the safety warning of mine fog by carrying out the research on mine fog,and points out the direction for the prevention and control of mine fog,which has certain reference value.The main research work is as follows:(1)The field survey summarizes that the fog in the mine in winter mainly appears in the return air route,and the results show that the density is between 0.909kg/m~3 and 1.016 kg/m~3,the vapour pressure of water in fogging shaft is between1227.96 Pa and 3013.66 Pa,and the humidity ratio is between 10.204 kg/kg(a)and22.424 kg/kg(a),the specific enthalpy ranges from 41.494 k J/kg(a)to 81.726 k J/kg(a),and water separation into fog ranges from 0.058 kg/d to 8.499 kg/d,indicating that the main cause of fog in the mine is the change of pressure reduction,cooling,enthalpy reduction and humidity reduction of the wet air state.(2)Based on the measured data,three mathematical models of water separation into fog in mine shafts are constructed,and a calculation software of water separation into fog is developed and designed according to the weighted MNLR model of influencing factors with the highest prediction accuracy,which is suitable for the plateau area mine,and can be used for the high-precision calculation of water separation into fog of main fogging shaft.(3)Through the construction of safety risk assessment index system of fogging shaft,combined with the game theory combination weight of evaluation index,the FCE method is used to evaluate the safety risk level of fogging shaft,and it is obtained that the high safety risk level of the shafts are mainly fogging ramp and inclined shaft,and the fog situation and safety risk factors in the ramp and inclined shaft should be paid more attention to.The corresponding protective measures are put forward.