A new approach to determining the yield of volatile substances from coals in relation to explosion safety, including expert work in emergency mines during explosions, is considered. The results are based on complex experiments, including explosive tests and thermogravimetric studies of gases of various stages of metamorphism: from long-flame (grade D) to coking (grade K). Thermogravimetric studies were supplemented by explosive experiments in a 20-liter chamber, and more than 60 dust samples from emergency mine sites were also studied. Refined “stage-by-stage” indicators of the yield of volatile substances for solving dust explosion problems, which have significant advantages over the standard method of quasi-isothermal heating of dust in a muffle furnace, have been proposed and practically worked out. Methods of thermogravimetric determination of moisture and ash content of samples, as well as the yield of volatile substances at various stages of heating, with separation of the yield of combustible and non-combustible gases, have been developed. Non-overlapping intervals of the thermal reaction are identified: moisture yield (25-130 °C); heat-resistant heating (180-350 °C); primary yield of volatile substances PVS (350-600 °C); secondary yield of volatile substances SVS (600-750 °C); thermal degradation of mineral inclusions and inert dust CDS (750-840 °C). For emergency conditions, the stages of steady decrease and growth of the yield of volatile substances from post-explosive samples are determined and a criterion for the participation of coal dust in the explosion is formulated. The modified criterion makes it possible to numerically recognize the fact of dust participation in an explosion, determine the epicenter of deflagration combustion, and study the dynamics of the explosion over a mining network while determining the effectiveness of dust and explosion protection.
Ensuring dust and explosion safety during underground coal mining is one of the most important tasks of industrial safety and labor protection departments. The main method of preventing explosions of coal dust settled in mine workings is to process them with stone dust (rock dusting). The traditional methods of quality control of rock dusting include radioisotope, optical and chemical methods. To implement them, the devices are equipped with environmentally harmful radioactive elements, expensive optical sensors, desiccants and replaceable flasks with chemical reagents, which increases the cost of analysis and its duration. The measurement error of these devices is 10 % or more. The main purpose of the study is to develop and substantiate a new method for monitoring the dust and explosion safety of mine workings, which will be devoid of the disadvantages of the methods mentioned above. It is proposed to evaluate the quality of rock-dust distribution by a fundamentally new way – thermogravimetric. The method was tested on the dust of coal mines in Kuzbass and the Vorkuta basin, including dust samples taken in mines with actual explosions. The article presents the results of experimental studies of the processes of thermal destruction of coal and stone dust mixtures. The non-overlapping intervals of the thermogravimetric reaction are identified: moisture yield (35-132 °С); volatile matter yield from coal (380-580 °С); thermal degradation of limestone with carbon dioxide yield (650-850 °С). Methods and mathematical dependencies for processing significant and qualitative identification characteristics of thermogravimetric curves in determining the content of non-combustible components in a sample of mine dust are considered.
The article describes the results of the implementation of investment projects in the field of complex dedusting implemented in major coal producing companies in Russia. Experimental study of the processes reduce the levels of dust in the workplace in the application of modern systems of irrigation and aspiration systems. The factors that determine the mass and composition of particulate airborne dust at various ways of dust suppression. The results of the analysis of the laser dispersed composition of particles removed from the air of the working area
