Research On Production And Transportation Laws And Control Technology Of Dust From Ore Unloading In Multi-level Ore Pass

The dust discharged from multi level ore pass is one of the main sources of dust in the mining process of metal mines.The dust discharged from any level of ore pass may cause dust pollution to other levels.The existing research on the production and transportation law of dust discharged from multi level ore pass is less,and the research on the dust reduction technology of multi level ore pass linkage is even less.Based on theoretical analysis,similar experiments and numerical simulation methods,the calculation model of impact flow and the model of dust production and transportation are established.The model of gas water spray and foam dust control for controlling ore unloading dust is studied.According to the law of the production and transportation of the ore unloading dust,the optimization experiments of gas water spray and foam dust reduction parameters were carried out,and the dustfall dust removal system was developed.Based on the energy conservation law,the function transformation of ore in the process of falling down in the ore pass is analyzed,and the calculation model of impact wind speed and gas flow in the ore pass is established.According to the theory of gas-solid two-phase flow and Fick’s law,the production and transportation mechanism of ore discharge dust is studied,the calculation model of the concentration of ore discharge dust at any time and position in the cross cut is deduced,and the main factors affecting the dust discharge are determined.At the same time,the principle of gas water spray and foam dust reduction is analyzed.The droplet size and wetting ability are the key factors that affect the effect of gas water spray and dust suppression,and the foam volume and foam stability are the key factors affecting the effect of foam dust reduction.In order to analyze the influence of unloading parameters of multi level ore pass on dust production and transportation law,the similarity criterion number of dust production and movement was deduced by using similarity theory.The similarity experimental platform of dust production and transportation law of multi level ore pass was established,and the influence of unloading parameters on impact wind speed and dust concentration was studied.Through the analysis of the dust discharge under the five discharge rates of 0.4 kg/s,0.6 kg/s,0.8 kg/s,1.0 kg/s and 1.2 kg/s,it is concluded that when the discharge rate is 1.0 kg/s,the dust discharge is the largest,and the third and fourth levels of multi level ore pass are the main dust producing levels.Through the analysis of the influence of the total amount of ore unloading,ore particle size,ore height and water content on the dust of ore unloading,it is concluded that the total amount and height of ore unloading are positively correlated with the dust of ore unloading,while the particle size and water content of ore are negatively correlated with the dust of ore unloading.By using high-speed camera,the dynamic relationship between the impact airflow and the discharge dust is studied.The results show that the movement of the dust lags behind the impact airflow.The movement speed of the impact airflow in the fourth level is 2.64 times of that of the dust.The dust production in the process of ore falling accounts for 78%of the total discharge dust,and the dust production after falling into the ore bin accounts for 22%of the total dust production.In view of the characteristics of dust dispersion in the ore outlets of multi level ore pass,the parameters of gas water spray were optimized through the experiment of air water spray and dustfall,and the optimum gas water flow ratio was determined to be 110～145.Based on the analysis of foaming parameters and foaming parameters,the optimum foaming agent formulation was determined.The optimum foaming gas liquid ratio was 31,and the foaming ratio was 21.According to the law of dust production and transportation obtained by similar experiments and numerical simulation,the hardware composition of dust linkage control system for multi level ore pass is determined,and the software of dust linkage control system is developed.Through the dust reduction experiment of the similar experimental model of dust production and transportation in multi level ore pass,it is concluded that the dust reduction rates of the system for the third and fourth level total dust are 79.2%and 84.1%respectively,and the dust reduction rates of the system for respirable dust are 71.2%and 78.6%respectively.The gas water spray dust control device of the linkage control system is applied to the fourth level of the field.The dusting rate of the whole dust reaches 82.5%,and the dusting rate of the dusting is 76.8%.Good dust reduction effect is achieved,which provides a new way for other mine dust control.