JUSTIFICATION OF USE OF A FACILITY FOR DRY PURIFICATION OF A COAL FROM THE SURFACE MINE “GACKO” WITH THE AIM OF INCREASING ITS HEATING CAPACITY

Abstract

Due to non-fulfillment of the overburden excavation plan until 2013 as a result of failure to follow the project dynamics of investing in the acquisition of the necessary mining equipment, the "Gacko" surface mine was brought to a state of impossibility of providing coal for the normal operation of the thermal power plant. The resulting situation was solved by the exploitation of coal from the lower coal layer (due to the favorable overburden coefficient), whose reserves were estimated at around 45 million tons, and which until then was treated as an off-balance sheet category. Excavation of coal from the zone that is nearest to the surface began in 2014, so more than 70% of the electricity production from the Thermal power plant was based on this coal (the rest of 30% was provided from field "C"), and in the last two years even all 100%. However, practice has shown that apart from selective mining, this coal should also be purified before use, in order to bring its lower coal heat capacity to the value required by the installed equipment of the thermal power plant, respectively the boiler in which it is burned. In the last few years, numerous geological investigations have been carried out for the purpose of a detailed definition of the coal seam, and work has also been done on finding the most optimal technical and technological solutions, which resulted in activities in the direction of application of both system of selective exploitation and the X-Ray sensor method of coal purification, considering that the deposit is very stratified with interlayers of marl and clay. Coal purification is also necessary for part of the quantities from the main coal layer of field "C", because the geological characteristics are partly unfavorable, due to the presence of tailings layers that affect the reduction of the lower coal heat capacity.The X-Ray procedure works on the principle of sensor classification of materials according to their properties, i.e. depending on its atomic density, the corresponding beam of X-rays passes through. Separation of materials according to the permeability of X-rays of a certain energy is carried out on the basis of the difference in the permeability of these radiations, whereby the best results are achieved at a granulation of -80+30 mm.Investing in the construction project of a coal purification facility is justified due to the provision of a reliable, stable and continuous flow of production in the Mine and Thermal power plantGacko, which is of vital importance both for the municipality of Gacko and for the Republic of Srpska, considering that it employs about 2000 workers and provides 1/3 of the total electricity production in the Republic of Srpska. Also, the use of a coal purification facility would lead to an improvement in environmental conditions through a reduction in environmental pollution, which would be reflected in less dust emission into the atmosphere, i.e. a reduction in the amount of ash at the output of the Thermal power plant. This would enable the prevention of possible negative consequences for the reputation of the company if it does not comply with the regulations on environmental protection, which are the basis of both business and quality policy, i.e. a positive image would be maintained through the implementation of an integral environmental protection management system according to ISO standards.The economic goals of investing in the project would be achieved by improving the effects of the thermal power plant's work by increasing its degree of useful effect, and thus by producing a larger amount of electricity on an annual level, then ensuring the continuity and regularity of its work by reducing the number and duration of downtime, and reducing the cost of electricity. So, the purpose of investing in a plant for dry purification of coal from the surface mine "Gacko" would be to continuously supply the thermal power plant with coal of the required quality, and to achieve the aforementioned social and economic goals of the company.