Comparison of Flotation and Screening as Separation Method in Coal Recovery From Tailings by Agglomeration

Dependency of Turkey on foreign energy adversely affects the economy of the country and may cause energy shortage in the near future. As a primary domestic energy source, coal is used for energy production in addition to imported oil and gas. However, significantamount of fine coal is lost together with tailings in coal washeries. Recovering of fine coals from these tailings will make an economiccontribution to country. In the present study, fine coals were recovered from tailings of a coal washery in Turkey by using oil agglomeration method. Flotation was used in agglomerate separation stage of oil agglomeration. Results were compared with that of previousstudy in which agglomerates were recovered by screening. The performance of the process increased sharply when flotation was usedinstead of screening in agglomerate separation stage. A clean coal with 28% ash was recovered from the washery tailings containing55% ash by 85% combustible recovery.

Coal Moisture Variations in Response to Rainfall Events in Mine and Coal-Fired Power Plant Stockpiles—Part 2: Evaporation

Additional moisture added in coal stockpiles due to rain and other climatic processes causes a significant problem worldwide, which leads to not only decrease in the heating value of the coal but also creates an extra efficiency penalty. Therefore, it is important to make some predictions for control of coal moisture within stockpiles after the rainfall. When the rain falls on the stockpile, it either runs off the surface or infiltrates the stockpile. The infiltrated water may evaporate from the surface, drain or stay within the stockpile. The aims of this study (parts 1 and 2) are to describe and compare the changes in coal moisture content following rainfall events. The mechanisms of runoff, infiltration and drainage after rainfall were described in the first paper of this series. In part 2 the influence of coal particle size and ambient conditions on the rate and depth of moisture evaporation within the stockpile is investigated. The laboratory experiments showed cyclic events of adsorbing moisture overnight and desorbing this moisture during the day as part of the coal surface evaporation process. The rate of evaporation from the surface of the fine coal stockpile was faster than the coarse stockpile; however, the coarse stockpile experienced a more efficient evaporation process because of its porous structure. Fine coal beds experienced evaporation only near the surface, while the maximum influencing layer of evaporation is a depth of 0.4 cm below the surface in coarse coal beds.

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.

SYNGAS DERIVED FROM CATALYTIC GASIFICATION OF FINE COAL WASTE USING INDONESIAN POTENTIAL CATALYST

Fine coal waste from the coal mining process has not been used as clean energy even though the amount is very abundant in the world. The conversion of fine coal to syngas is a new way to increase the value of fine coal. Syngas composition, gas ratio, gasification efficiency, and heating value of syngas have been determined under various conditions of temperature (550-750 °C) and bentonite catalyst ratio (0-0.25). The results indicate that fine coal is the suitable raw material for the gasification process. At the highest temperature (750 °C), the gas composition consists of 42.6 vol% H2, 19.1vol% CO, 19.5 vol% CH4, and 7.9vol% CO2. The best performance was achieved when the catalyst/feed ratio is 0.25 with the gas composition of 54.3vol% H2, 26.2vol% CO, 23.8 vol% CH4, and 3.5vol% CO2, heating value and gasification efficiency were 19.72 MJ/Nm3 and 72.27% at 750 °C.