Multi criteria genetic algorithm for optimal blending of coal

Coal gasification is the most demanding technology, increasing day by day for synthesis gas and chemical production in a clean environment. Coal is a primary source of energy or fuel. India has a high preservation of high-ash coal. Employment of this coal for gasification is tough due to its abrasive nature. Coal blending is an effective way to utilize such coal and to control the gasification performance. The present study focuses on using high-ash, low-rank Indian coal with high-rank imported coal in a suitable blend. The blending effect on raw gas yield (kg/kg of coal) and heating value (kcal/Nm3) was studied for coal blends-CH1 (20:80), CH2 (30:70), CH3 (40:60), CH4 (50:50), and CH5 (60:40) of RC (raw Indian coal) with RH (raw high-rank imported coal). Also, the gasification characteristics of the WC (washed Indian coal) were studied similarly. It may be seen that the raw gas yield with blends of raw coal and the rank of imported coal is 1.11 to 1.46 (ton/ton of coal), whereas in washed Indian coal, it is 0.95 (ton/ton of coal). A slight change was observed in the heating value of raw gas, and its average value in the blended CH1 to CH5 coal is 2860 kcal/Nm3, whereas in WC, it is 2956 kcal/Nm3. The maximum utilization of raw coal in the blend for gasification can be 60%, which is economical and 0.55 times more effective than WC gasification.

Briquette coals with different cement contents are frequently used to study the coal body’s properties. In this study, the deformation and strength of briquette coal samples with 0, 5, 10, and 20% cement contents were experimentally and theoretically investigated using the acoustic emission (AE) characteristics monitored during the uniaxial compression tests. The results show that the uniaxial compression process of raw coal and briquette coal samples can be subdivided into compaction, elastic, plastic (yield), and brittle failure stages. With an increase in cement content, briquette coal samples undergo the elastic and plastic stages, and their postpeak stress drop rate gradually grows, and their plastic deformation is followed by brittle failure. The uniaxial compressive strength and elastic modulus of briquette coal samples show a linearly increasing relationship with cement content, while their Poisson’s ratio decreases gradually. During the uniaxial compression, raw coal and briquette coal samples produce the AE signals. The overall AE signal of briquette coal samples is relatively low, and there are no obvious AE events in raw coal samples. The uniaxial compressive strength, elastic modulus, and Poisson’s ratio of briquette coal samples with a 20% cement content and their AE signal cumulative amplitude, count, and energy values are very close to the corresponding parameters of raw coal samples. Therefore, they can be used for simulating raw coal samples in laboratory tests.

Consumer market demand for certain specifications of coal continues to increase every year. However, each coal company has a variety of coal qualities in terms of calorific value, water content, ash content, and total sulfur and so on. PT. Alamjaya Bara Pratama is a coal mining company that has several types of coal products that vary in quality. By coal blending, the aim is to obtain coal product that meet the target with a homogeneous composition and according to consumer coal quality specifications. With the linear programming method for coal blending calculations using the Production and Operation Management - Quantitave Methods software has an influence in maximizing the use of the composition quantity for each type of product (MD and HS) as well as optimizing the quality of the coal blending results. Through POM-QM, it has the advantage of being able to determine the benchmark target value for one of the desired coal quality parameters. With subbitumious coal quality as for the research results are calculations of the final quality for each Mother Vessel, one of which is MV Eastern Camelia with the planning results is (AC 5,0% adb, TS 0,90% adb, GAR 4590 kcal/kg arb) with tonnage requirements for coal products (MD = 29.727,84 MT and HS = 22.772,16 MT). Through the use of linear programming (POM-QM) in calculating coal blending planning, the results are obtained and meet each coal quality parameter limit criterion based on consumer demand.

Coal is the most valuable gasification resource due to its abundance and low cost for commercial applications. But utilization of low-rank Indian coals for gasification is challenging due to difficulty in washing. For utilizing low-grade high ash raw coal, blending is one of the effective methods to control the gasification performances. So, the present study explores the gasification of such a low-rank raw coal blend and compares the results with washed coal blend. The blending effects on raw gas yield (kg/kg of coal) and heating value (Kcal/Nm3) were investigated for coal blends-WH (washed coal with high-rank coal) and RH (raw coal with high-rank coal). In WH, raw gas yield is 1.210 to 1.225 (kg/kg of coal), whereas, in RH is 1.189 to 1.213 (kg/kg of coal), though the fixed carbon content of WH (40.75–41.74%) is lower than RH (44.73–45.25%). In washed coal, raw gas yield is minimum (0.75 kg/kg of coal). The heating value is lower in WH (2730–2871 Kcal/Nm3) than in RH (2884–2978 Kcal/Nm3). Statistical correlation is developed between gaseous components of raw gas and heating value; H2/CO ratio is the most significant parameter. RH gasification is economically viable than WH.

The reduction of greenhouse emissions, the reduction of ash fouling and the improvement of thermal efficiency are major issues facing electricity generating companies, particularly those using coal. The high water content of lignites is a major disadvantage with regard to power generation efficiency, as current technology uses energy to evaporate the water directly. Two pretreatment processes, hydrothermal dewatering (HTD) and mechanical thermal expression (MTE) have been evaluated to remove water as a liquid from coals, thereby avoiding the need to supply latent heat for vaporisation. This can improve efficiency of power generation from lignites and reduce greenhouse emissions per unit of electricity generated. In both processes the fluid pressure is maintained greater than saturation pressure to prevent evaporation. In HTD, dewatering is related to irreversible pore collapse following structural changes on heating. In MTE water is removed as pores collapse through the application of mechanical force. Furthermore, inorganics, particularly Na, are leached from the coal into the wastewater, decreasing the fouling potential of the product during combustion. Raw Loy Yang brown coal, 62% water (by weight), was processed in small batch MTE and HTD units at varying temperatures. The raw coal was also subjected to different mechanical pressing pressures in the MTE unit. The coal products were analysed by ultimate and proximate analysis, helium pycnometry, CO2 surface area and mercury porosimetry. The treated coal was found to lose only a small amount of volatile material at processing temperatures up to 250°C. However, an increase in processing temperature to 320°C (HTD) significantly increased the loss of volatile material, reduced the moisture content of the filter cake, decreased the large-pore (0.03-1µm radius) volume of the coal and increased the concentration of organic material in the wastewater. An increase in mechanical pressure in the MTE unit from 6–12MPa was found to increase the density and decrease the porosity, decrease the moisture content and also increase the carbon content of the product. The amount of water remaining in the coal products correlated strongly with the residual pore volume.

Experimental research was carried out on the manufacturing of bio-coal briquettes from a blend of two different types of low-quality coal and biomass waste in the absence of coal carbonization, where the third blend of the material was fermented by adding a bio-activator solution before pressurizing the components into briquettes. The coal samples from Caringin–Garut Regency (BB–Garut) had a low calorific value and a high sulfur content (6.57 wt%), whereas the coal samples from Bayah–Lebak Regency (BB–Bayah) had a higher calorific value and a lower sulfur content (0.51 wt%). The biomass added to the coal blend is in the form of fermented cow dung (Bio–Kohe), and it had a calorific value of 4192 kcal/kg and a total sulfur content of 1.56 wt%. The main objective of this study is to determine the total decrease in the sulfur content in a blend of coal and biomass in which a fermentation process was carried out using a bio-activator for 24 h. The used bio-activator was made from Garant® (1:40) + molasses 1 wt%/vol, and its used amount was 0.2 L/kg. Also, the total sulfur content in the blend was 1.00 wt%–1.14 wt%, which fulfills the necessary quality requirements for non-carbonized bio-coal briquettes. The pyritic and sulfate content in the raw coal was dominant, and the organic sulfur, when fermented with Garant®, was found to be less in the produced bio-coal briquettes by 38%–58%.

INFLUENCE OF COAL QUALITY AND ITS PREPARATION ON THE EFFICIENCY OF COAL CHARGE TAMPING AND COKE QUALITY © D.V. Miroshnychenko1 , V.V. Koval2 , O.L. Borysenko3 , L.P. Bannikov4 STATE ENTERPRISE ‗UKRAINIAN STATE RESEARCH INSTITUTE FOR CARBOCHEMISTRY (UKHIN)‘, 61023, Kharkiv, 7 Vesnina St., Ukraine N.V. Mukina5 PJSC "ArcelorMittal Kryvyi Rih", 50095, Dnipropetrovsk Region, Kryvyi Rih, 1 Kryvorizhstali St., Ukraine S.G. Nedbaylo6 National Technical University "Kharkiv Polytechnic Institute" (NTU "KhPI"), 61002, Kharkiv, Kyrpichova St., 2, Ukraine 1 Miroshnychenko Denis Viktorovich, Doctor of Technical Sciences, Prof., Chief Researcher of Coal Department (СD), e-mail: dvmir79@gmail.com 2 Koval Valentyn Valeriyovych, Ph.D. in Technical Sciences, Senior Researcher of CD, e-mail: kovalen79@gmail.com 3 Borysenko Oleksandr Lyudvikovych, Ph.D. in Technical Sciences, Senior Researcher, Acting Director, e-mail: zd@ukhin.org.ua 4 Bannikov Leonid Petrovich, Doctor of Technical Sciences, Head of the Chemical Department, e-mail: ukhinbannikov@gmail.com 5 Mukina Natalia Volodymyrivna, Ph.D. in Technical Sciences, Head of the Technical Department of Production Management of the Coke-Chemical Plant, e-mail: Natalia.Mukina@arcelormittal.com 6 Nedbaylo Serhiy Gennadiyovych, postgraduate student of the Department of Technologies of Oil, Gas and Solid Fuel Processing The paper presents the results of a study of real coal blends of different compositions intended for coking by charging into the chamber through stamping. The problem of ensuring high-quality blast furnace coke is one of the key issues for the steel industry, since coke performs energetic, chemical, and physical functions in the blast furnace process. Under wartime conditions, limited supply, and the high cost of high-quality coking coal, the optimization of coal blend composition and the improvement of its preparation technology acquire particular importance. It was established that with an increase in the content of gas coal of a low degree of metamorphism and a corresponding decrease in the share of coal of a high degree of metamorphism, a gradual deterioration of coke quality indicators is observed. This is reflected in a reduction of coke yield (from 75.2 % to 73.6 %), an increase in abrasion (from 7.3 % to 8.0 %), as well as in the deterioration of ―hot‖ strength (CRI up to 40.8 %, CSR down to 45 %). At the same time, the stampability of the blends decreases (from 22.5 to 21.1 kPa), the expansion pressure reduces (from 6.8 to 5.9 kPa), and the stamping work required to achieve the specified cake density decreases (from 8966 to 6822 J). It was also shown that the degree of blend grinding has a significant effect on energy consumption: with a decrease in the average particle size, the stamping work decreases from 7407 to 6238 J. In addition, it was found that an increase in the content of DG+G coal grades leads to a higher yield of coking by-products, in particular crude benzene and CO₂, while the properties of tar and the satisfactory characteristics of ammoniacal liquor remain unchanged. This is important for the efficiency of subsequent treatment of condensates and wastewater. The obtained results indicate that, under the existing limitations of the raw material base, the second variant of the coal blend composition is the most optimal. It ensures acceptable coke quality at a lower cost and can be recommended for industrial application. The practical significance of the study lies in determining the regularities of the influence of petrographic and granulometric characteristics of coal blends on the stamping process and coke properties, which provides a basis for improving the efficiency of steel production in Ukraine under the conditions of a shortage of high-quality coking coal. Keywords: coal concentrates, coal blend, coal charge preparation, tamped coal cake, tamping work, strength of the tamped coal cake, coke quality. Corresponding author: V.V. Koval, e-mail: kovalen79@gmail.com

Some countries have enacted specifiic legislations for landuse management in mining areas. The position in India is causing serious concern and the Government has taken active interest to control land degradation. One among various protective measures taken in India is aforestation, because, green-belts, other than agriculture, have enviornmental utility. Landuse management in mining areas is concerned mainly with environmental degradation due to mining, the focal subject being waste disposal and quarry and goaf filling. Landuse management schemes taken up by some mining areas in India have been discussed. As a specific case, the Jharia Coalfield has been studied in detail. A landuse map of the area has been prepared based on study of aerial photographs and maps. The landuse management scheme suggested in India has not yet been properly implemented. Some steps to help the rapid development of the scheme has been suggested.

Large-scale diversion of Indian coking coal to the non-metallurgical sector has been pointed out by the authors and others on various forums. One of the principal reasons, indeed, is the lack of coal preparation facilities to treat the entire quantity of raw coking coal to make it suitable for coke making. However, the poor capacity utilization of the existing facilities and poor organic efficiency are the issues that, if addressed properly, can change the whole coal-washing scenario in India. Having carried out systematic studies on the performance of some of the coking coal washeries in Jharia coal field, authors are of the opinion that the problem cannot be solved entirely by focusing only on technical aspects. Meticulous resource planning, staffing, and change in management strategy are as important as optimizing operational efficiencies. Hence, the authors have delved into all the aspects of a working coal preparation plant and identified several measures to improve its performance.

Purpose. To calculate the parameters of the development of brown coal deposits, including the limiting overburden ratio, when involving coal clay into the development together with brown coal in the composition of the coal mass. Methodology. To calculate the cost of mining a mineral, the method of financial and mathematical averaged costs was applied, considering the level of projected capital investments and the cost of investment funds. Findings. The influence of the involvement of coal clays in the development together with brown coal as a part of coal mass on the limiting overburden ratio is investigated. It is determined that the limiting overburden ratio for a mining enterprise that extracts brown coal is 20 m3/t, and for the extraction of coal clay in a mixture with raw brown coal 17 m3/t. The parameters of brown coal production in Novo-Dmytrivske deposit have been established, which have shown that with a coal production of 9 million tons/year, the overburden ratio is 4 m3/t. In the case of extraction of associated minerals in the form of coal clays, the opencast capacity can increase up to 20 million tons/year, and the overburden ratio will decrease down to 1 m3/t. Originality. The dynamics of the change in the current overburden ratio over the years for the extraction of coal mass with the share of coal clays from 0 to 50% for the conditions of Novo-Dmytrivske brown coal deposit has been established. The costs to produce raw coal have been determined in terms of both natural and conventional fuel. The modelling of the costs for the extraction of minerals and rock mass, depending on the overburden ratio, has been carried out. The change in the overburden ratio was determined when coal clay and off-quality brown coal were involved in the production in comparison with the production of raw brown coal. Practical value. It has been established that those deposits and areas that were previously related to the development of the mine method or open-pit mines with large losses of coal during the complex mining of conditional seams of raw brown coal, off-quality seams, and coal clays, can potentially be mined with minimal losses of useful fossil and with low cost.

Organic geochemistry characterization of the density fractions of a Permian torbanite

Characterization of coal blends for effective utilization in thermal power plants

ABSTRACTTo produce low-cost hot metal, Tata Steel always had to deal with trilemma, that is, cost-quality-mining life to achieve maximum benefit in the steel business. Tata Steel used approximately 50–60% Indian medium captive coking coal having 15–16% clean coal ash in the stamp charged coal blend. Keeping in view, consumption, and preservation of the Indian medium coking coal by modulating clean coal ash without deteriorating the coke quality was the subject of the study. The study revealed that 55% captive Indian medium coking coal up to 19.10% clean coal ash in coal blend could be used to produce coke CSR ≥65. It also reduces the coal blend cost with added benefits of the increase in the captive mine life. This paper described in detail, the effect of variation of ash percentage of captive medium coking coal in the blend on the lateral expansion and hot strength of coke especially of coke CSR.

Sources of air pollution due to coal mining and their impacts in Jharia coalfield

China has the largest coal production in the world due to abundant resource requirements for economic development. In recent years, the proportion of opencast coal mine production has increased significantly in China. Opencast coal mining can lead to a large number of environmental problems, including air pollution, water pollution, and solid waste occupation. The previous studies on the environmental impacts of opencast coal mine production were focused on a single production process. Moreover, mined land reclamation was an important process in opencast coal mine production; however, it was rarely considered in previous research. Therefore, this study attempted to perform a whole environmental impact analysis including land reclamation stage using life cycle assessment (LCA) method. The Yimin opencast coal mine was selected to conduct a case study. The production of 100tons of coal was used as the functional unit to evaluate the environmental risks in the stages of stripping, mining, transportation, processing, and reclamation. A total of six environmental impact categories, i.e., resource consumption, acidification, global warming, solid waste, eutrophication, and dust, were selected to conduct this assessment. The contribution rates of different categories of environmental impacts were significantly different, and different stages exhibited different consumption and emissions that gave rise to different environmental effects. Dust was the most serious environmental impact category, and its contribution rate was 36.81%, followed by global warming and acidification with contribution rates of 29.43% and 22.58%, respectively. Both dust and global warming were mainly affected in mining stage in Yimin opencast coal mine based on comprehensive analysis of environmental impact. Some economic and feasible measures should be used to mitigate the environmental impacts of opencast coal mine production, such as water spraying, clean transportation, increasing processing efficiency, and improving mining technologies. This study can be considered as a useful reference for a deeper understanding of key environmental impacts related to the whole coal production in opencast coal mine.