Hygienic standards of dust . air in industrial premises and underground workings, approved by the USSR Gossaninspektsiya, are differentiated by type and composition of dust (SN 245-63). They do not take into account a number of factors that affect the amount of dust penetrating into the human body: different heights of mines and mines, climatic conditions, the degree of severity of the work performed, the duration of human stay in a dusty environment ...
As a rule, mines in the Far North, which develop coal seams in permafrost conditions, are characterized by seasonal fluctuations in the dust content of the mine atmosphere. In January - February, the content of dust in the air during excavation, loading and transportation of coal reaches the maximum value - hundreds and thousands of milligrams per 1 m3, and in summer it approaches the sanitary norm ...
Seasonal fluctuations of air dustiness in mines in the permafrost region are known to be associated with the processes of evaporation and condensation of moisture, which take place in mine workings in cold and warm periods of the year, respectively. The former increase and the latter reduce dust generation during excavation, loading and transportation of coal ...
The air ducts used in mines and underground workings for ventilating development workings are largely air-permeable, especially at pipe joints. It is not possible to achieve airtightness even with advanced types of joints (rubber gaskets, rings, banded connections, etc.).
Most of the mines we surveyed in the north-eastern part of the country (Norilsk, the Yakut ASSR and other areas) develop mountainous coal deposits lying in the permafrost zone using adit development. As a rule, the mines operate without pre-heating of air during the cold season. Therefore, in the area of extraction panels, with the exception of individual cases, the temperature of the mine atmosphere remains negative throughout the year (minus 2 to minus 4 °C) ...
Calculation of mine air ducts by analytical and graphoanalytical methods is mainly reduced to the determination of two quantities: 1) air leakage or the delivery coefficient μ; 2) the head h, which must be provided so that a given amount of air Qzab reaches the end of the stack of pipes. Many formulas for calculating these values have been proposed. A. I. Shvyrkov, on the basis of theoretical studies of air movement in air‑permeable pipelines, established a functional dependence between these quantities.
The possibility of using the wet method of dust suppression at the mines of the Norilsk Combine during excavation, loading and transportation of coal was established by thermometric measurements of air and host rocks along the course of the ventilation jet. The research was carried out by the staff of the Department of Mine Ventilation of the Leningrad Mining Institute in 1959-1960.
Internal air leakage of local ventilation fan at individual work. Local ventilation of dead-end mine workings during sinking is carried out by local ventilation fans and ventilation pipes. Mine pipelines are mostly leaky and leak a significant amount of air at the joints. The amount of air entering the face through the pipeline Qface can be so small that the ventilation will be ineffective even at fan capacity Qfan exceeding several times Qface. With the increase in the length of excavations, the control of air leakage along the length of the pipeline is of paramount importance.
