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Coal is the most abundant fuel on earth and Low-rank coal (LRC) such as sub-bituminous, lignite take about half of its deposit. But LRC cannot be conveniently used due to low caloric value and high moisture content, being rich in oxygen and high tendency to spontaneous combustion. It is necessary to solve the above problems in order to use low rank coals as efficiently as possible. One of the efficient methods is to upgrade LRC. In this study, drying techniques in immersed hot oil is used for upgrading LRC. This process is executed in relatively low temperature and low pressure, so energy cost of upgrading process is reduced largely. Indonesian lignite (moisture content 32%, high heating value 3,000 kcal/kg) is upgraded to moisture content 2.0 ~ 3.2% in 10 minutes, high heating value 6,000 kcal/kg through upgrading process in evaporative drying equipment with refined waste oil and B-C heavy oil having temperature of 120℃, 130℃ and 140℃, respectively.