Analysis of historical changes in the limit value of nitrogen oxides concentrations for underground mining

Abstract

Abstract Providing adequate ventilation in underground mines is a growing problem. The constantly increasing depth of exploitation is a challenge for ventilation services. However, not only the depth of exploitation, but also the increasing knowledge of the impact of noxious factors on the health of employees contributes to the constant changes in the values of permissible concentrations of gases to improve working conditions. One of the main hazards to which the restrictions are introduced is the gas hazard. Nitrogen oxides are one of the most important gas compounds that occur in underground mining plants. The article will present the beginnings of recognizing hazardous gases as harmful and the history of limiting the concentrations of these compounds in underground mines. The restrictions concern compounds from the NOx family, such as nitrogen oxide (NO) and nitrogen dioxide (NO2). The concentration limits in force in Poland refers to both European directives and regulation acts issued in our country. The subject of nitrogen oxides in the world has recently been very important, and in Poland, it mainly concerns copper and salt mines. Although research has not yet been officially carried out to identify the sources of nitrogen oxide emissions in mines, it is recognized that most of these compounds come from exhaust gases produced by self-propelled mining machinery with diesel engines. It is presumed that nitrogen oxides enter the mine atmosphere also through a blasting and from the natural outflow of these gases from the rock mass. The presence of nitrogen oxides in the mine atmosphere in Polish copper ore mines is related, among others, to the mineral o the mineral mining cycle.