Studying the effect the physicochemical properties of fine size raw coal organic and mineral composition have on beneficiation efficiency

Introduction. This work presents the results of the research on the effect the petrographic characteristics, elemental and mineral composition have on the Kedrovsko-Krohalevskoe fine coal beneficiation efficiency. The data has been analyzed of raw coal physochemical properties at the stage of mining and dressing mill raw material base formation. Research objective is to study thermal coal by physicochemical methods of analysis to identify the main parameters affecting the quality of beneficiation products. Based on the data obtained, the research aims to develop the method of assessing the indicators affecting the beneficiation process and further forecasting during the development of new areas and coal seams. Methods of research. The structural features of raw KCN (coking low-caking low-metamorphosed) coal were determined by comparative analysis of three samples according to the following parameters: laboratory flotation results, general technical parameters, maceral composition, organic matter elemental composition, and ash mineral composition. Results. It has been established that coals of a similar nature of origin and stage of metamorphism, can have different indicators in vaarious parameters: particle size, number and morphology of microcomponents according to quantitative petrographic analysis, as well as the presence of hydrophilic functional groups on the surface of coals. Conclusions. The results of the studies made it possible to identify a number of dependencies that can be used in a preliminary assessment of the quality of raw coal sent to a coal processing enterprise.

Substantiation into Parameters of Carbon Fuel Production Technology from Brown Coal

Technological solutions for brown coal processing, thermal influence on it at temperature change, thermo vacuum drying are analysed and qualitative and quantitative characteristics of semi – coking products are studied. The parameters of crushing and thermo vacuum drying of brown coal, heat treatment and cascade separation (electrostatic and magnetic) are substantiated. Studies on the manufacture of a pilot batch of carbon fuel with high quality characteristics are performed. Cascade treatment of heat-treated brown coal on electric and magnetic separators allowed to obtain a concentrate with ash content from 17.72 to 22.8%, volatile yield ≤ 35%, higher heat of combustion from 7256.1 to 7523.6 kcal/kg. It is determined that favourable modes of preliminary heat treatment of brown coal samples are in the temperature range of 200-400°С. The established characteristics of the obtained solid fuel correspond to the gas group of thermal coal. The obtained technological solutions for the processing of brown coal can be the basis for the manufacture of an industrial line, taking into account the thermo vacuum installation for further implementation in enterprises using carbon fuel.

A Study on Bituminous Coal Base Acid Ratio to the Slagging Factor at Large Scale Boiler

Different types of coal have different characteristics and performances. In thermal coal plant, deposition of coal ash inside the furnace causes slag formation inside the boiler rear path and consequently reduces the heat transfer process and boiler efficiency. Besides, accumulation of ash on the boiler tube surfaces form layers of slags and blocks the flue gas flow out of the boiler. Therefore, the purpose of this study is to investigate the relationship between sub-bituminous coal base acid ratio towards the heat transfer process inside large-scale boilers. The base acid ratio for sub-bituminous coal is measured before firing inside large-scale boiler of studied the thermal plant which has a generation capacity of 700 MW. This study found correlation between high furnace rear path temperature (FRPT) that is observed to be above 800℃, with the build up of ash accumulation inside the boiler, for the studied coal. Thus, a high base acid ratio causes the accumulation of coal ash, thus reducing the heat transfer process which results in high FRPT of the boiler. Therefore, it proves that a base acid ratio is an indicator for coal performance during firing inside the boiler.

PRIMARY ASSESSMENT OF THE DEGREE OF TORREFACTION OF BIOMASS AGRICULTURAL CROPS

Biomass energy is an important component in the overall structure of renewable energy and has the greatest potential for increasing volumes. However, the peculiarities of the properties of agro-industrial residues are a significant disadvantage of their widespread use. The process of torrefaction allows to bring the characteristics of biofuel as close as possible to thermal coal. Different degree of heat treatment of biomass leads to a product with different heating value. Therefore, it is important to know the optimal mode of torrefaction, which will provide the best energy parameters of biofuels.Researches of torrefaction were carried out on the basis of educational and scientific laboratory "DAK GPS" of the State Agrarian and Engineering University in Podilia. The kinetics of the relative mass of different types of biomass at different processing temperatures was considered. The dependence of the degree of torrefaction on the heat treatment temperature is revealed. As shown by studies for most biomaterials of plant origin, we can distinguish the beginning of intensive transformation and its end, after which there is a sharp slowdown in weight loss, and, accordingly, and the energy density of the samples.

Thermal Processing of Thermal Coal Under Pressure to Produce Semi-Coke and Thermal Energy

The process of thermal processing of brown coals of grades 1B and 2B under external overpressure of gases in the range of 0–4.0 MPa is investigated. The dependences of the main characteristics of the obtained products – semi-coke and combustible gas-on the pressure are established. The material and energy balances of the process of thermal processing of both coal grades are given

A Hybrid LSTM-Based Ensemble Learning Approach for China Coastal Bulk Coal Freight Index Prediction

China Coastal Bulk Coal Freight Index (CBCFI) reflects how the coastal coal transporting market’s freight rates in China are fluctuated, significantly impacting the enterprise’s strategic decisions and risk-avoiding. Though trend analysis on freight rate has been extensively conducted, the property of the shipping market, i.e., it varies over time and is not stable, causes CBCFI to be hard to be accurately predicted. A novel hybrid approach is developed in the paper, integrating Long Short-Term Memory (LSTM) and ensemble learning techniques to forecast CBCFI. The hybrid LSTM-based ensemble learning (LSTM-EL) approach predicts the CBCFI by extracting the time-dependent information in the original data and incorporating CBCFI-related data, e.g., domestic and overseas thermal coal spot prices, coal inventory, the prices of fuel oil, and crude oil. To demonstrate the applicability and generality of the proposed approach, different time-scale datasets (e.g., daily, weekly, and monthly) in a rolling forecasting experiment are conducted. Empirical results show that domestic and overseas thermal coal spot prices and crude oil prices have great influences on daily, weekly, and monthly CBCFI values. And in daily, weekly, and monthly forecasting cases, the LSMT-EL approaches have higher prediction accuracy and a greater trend complying ratio than the relevant single ensemble learning algorithm. The hybrid method outperforms others when it works with information involving a dramatic market recession, elucidating CBCFI’s predictable ability. The present work is of high significance to general commerce, commerce-related, and hedging strategic procedures within the coastal shipping market.

An Evaluation of the Australian Coal Flotation Standards

Mining operations often send samples for testing to commercial laboratories. Unless a customised test is requested, they expect laboratories to use standard procedures, which are reproducible. A thermal coal and a metallurgical coal were sent to eight laboratories, which were requested to perform a basic flotation test (AS 4156.2.1–2004) and a sequential flotation procedure test, i.e., standard tree test (AS 4156.2.2–1998). This study compared the reports produced by the various laboratories and compared them with the requirements laid out by the Australian standards. It was found that many elements were missing in most cases, probably due to the fact that some of the requirements of the standard, such as size analysis, are offered as other services. The basic tests generally agreed with one another whilst the sequential tests presented more variations. A quantitative analysis of the variation in the yield–ash curves produced by the sequential procedure was conducted using dynamic time warping (DTW). This approach can be used to numerically compare yield–ash curves and perform statistical comparisons.

Combustion characteristics of high ash Indian thermal, heat affected coal and their blends

Onsite mine fire generates large volumes of heat-affected coal in Jharia coalfields, India. Direct utilization of such heat-affected coal in thermal utilities is not feasible as such coal does not have the desirable volatile matter required for combustion. In the present work, experimental studies have been carried out to investigate the possible utilization of such heat-affected coal in thermal utilities by blending with other coal. Heat-affected coal (31% ash and 5300 kcal/kg GCV) collected from Jharia coalfield were blended with thermal coal (28% ash and 5650 kcal/kg GCV) in different ratios of 90:10, 80:20, 70:30 and 60:40 to identify the desirable blend ratio for burning of blended coal in thermal utilities. Burning characteristics of all the coals were carried out using TGA. Various combustion parameters such as ignition temperature, peak temperature, burnout temperature, ignition index, burnout index, combustion performance index, rate and heat intensity index of the combustion process and activation energy were evaluated to analyse the combustion process. Experimental and theoretical analysis shows the blend ratio of 90:10 can be used in place of only thermal coal in utilities to reduce the fuel cost.

Paris Agreement on Climate Change, Covid-19 and Hydrogen Energy – New Realities of Coal Mining and Consumption in the EU and Asia in the Period until 2040

The damage caused by burning of coal is currently much higher than that produced by using alternative energy sources. This explains the growing urgency to implement the Paris Agreement on Climate Change, which, as of November 2020, has already been signed by more than 170 countries. The study analyzes the volumes of coal production by the world's coal market leaders over the period from 2000 to 2019. Despite an overall increase in global coal production by 1.5% in 2019 as compared to 2018, which reached 7.9 billion tons, there was a decrease in coal mining rates by 3.4% and 3.5% against the previous two years. The rapid decline in the importance of coal-fired power plants in the electric power generation of the European Union and Asia who seek to shift to renewable energy sources and hydrogen power, makes further growth in exports of Russian thermal coal quite problematic in the post-crisis period. Most probably, the declining trend in coal production and consumption will continue and even intensify in the coming years. The fall in coal mining and consumption in 2020 alone can reach 25% in the USA, 5–10% in Japan and South Korea, 20% in the EU countries, and 9% in China. The use of hydrogen fuel will make significant changes in the supply not only of the Russian coal, but also of the Russian natural gas and oil. The demand for these commodities will be decreasing.