Developing the methods of controlling dust and gas conditions when blasting high benches in deep pits

Abstract

Research aim is to develop a method of reducing dust and gas emissions concentration at bulk explosions in open pits. Research relevance. When drilling and blasting in open pits, a huge amount of dust and toxic gaseous products is released, and the rate of their formation is affected by the blasting method, the range of explosives used, the method of drilling blast holes, type and sort of stemming, massif water content, rock properties, meteorological conditions, etc. It has been established that in an explosion of 1 kg of explosives, 15% from an average of 900 liters of various gases and gaseous products formed are toxic and dangerous to humans and the environment. To prevent dust and gas emissions, various types of tamping are currently used, which affect not only emissions reduction, but also the efficiency and safety of blasting contributing to the fullest use of explosion energy and increasing the exposure time of the products of explosive 120 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 4. 2020 ISSN 0536-1028 transformation. Despite the significant amount of research and successes achieved in this direction, for deep pits it is necessary to determine the rational parameters of stemming in borehole explosive charges, reduce the formation of toxic gases released in bulk explosions, develop a method of producing an absorption solution capable of neutralizing toxic compounds after an explosion, and develop an effective way to reduce dust and gas emissions in bulk explosions. Research methodology. To solve this problem, integrated research methods were used, including theoretical generalizations and experimental studies in laboratory, testing ground and industrial conditions, methods of mathematical modeling of stemming parameters in borehole explosive charges, methods of mathematical programming using modern computer equipment, as well as methods of mathematical statistics and correlation analysis of research results. Results. Detonation products pressure change in the well has been determined taking into account motion processes of sand and absorbing mixture stemming of various lengths. It has been established that when using stemming made of absorbing mixture, detonation products pressure and escape time are higher compared to sand stemming. The effective stemming length in borehole explosive charges has been established depending on well pressure fall time and stemming length in different sections of the well. Mathematical modeling of stemming parameters in the explosion of borehole explosive charges established the change in pressure in the blast chamber as a function of stemming time and length during its escape from the well, as well as the of stemming escape duration and expiration of detonation products during emulsion explosive blast depending on stemming length. A method has been developed of dust and gas atmospheric pollution parameters determination during the production of bulk explosions in deep pits, An absorption mixture has been developed, which makes it possible to intensify the process of dust deposition above the explosion site and reduce pollution of the surrounding quarry, which favorably affects the environmental situation in the mining region. A method has been developed to reduce dust and gas emissions during blasting operations in open pits, which allows to reduce the concentration of dust and gas clouds formed. Scope of the results. A method of suppressing dust and gas emissions has been introduced at the Muruntau open pit of the Navoi Mining and Metallurgical Combinat. As a result, the process of dust deposition above the explosion site has been intensified, pollution of the surrounding open pit area has been reduced, the concentration of nitrogen dioxide has been reduced by 30.1%, carbon monoxide by 28.6% and sulfur dioxide by 20.5%. The results can be used in quarries where rock crushing is carried out using a blasting method