Vol. 24 No. 2 (2021): INDONESIAN MINING JOURNAL, Vol. 24 No. 2, October 2021

This IMJ of October issue consists of five papers. Two of them relates to minerals and the rest speaks about coal. High temperature and energy are required processing nickel laterite. Yet such a requirements need a high budget. An alternative solution was made by processing the nickel laterite through selective reduction with additives. Sulfur is one of the additives but it needs to investigate the effect of sulfur content in the reductant on selective reduction of lateritic nickel ore as stated in one of the issued papers. Another paper that relates to mineral is the use of bio-organo mineral as an ameliorant for Camellia sinensis (L.) O Kuntze or known as tea plant. The results showed that there was a significant effect of the combination of conventional fertilizer and BIOM ameliorant on shoot production and pekoe percentage. The application of BIOM ameliorant was able to improve plant health after pruning on the GMB 7 clone.

Three other papers discuss about the coal. One of them reviews the chemical characteristics of coal and biomass mixture and its tendency of its ash deposition. Making a formula for economical complex soil conditioner of bio-organo mineral for tea, coffee and cacao plantations is the research objective based on such chemical characteristics and it provides a good result as stated in one of the published papers. One paper relates to coal discusses the temperature and moisture content of low rank coal on slow pyrolisis process. Based on the variations of the used temperature, a higher temperature of pyrolysis produced fewer char but its calorific value of coal product was also higher; the optimum operating condition was achieved at 500-600°. The application of failure method probability for analizing in pit dump stability at West Block ‘X’ pit PT Berau Coal - East Kalimantan is the paper that also relates to coal. The purpose of this study is to determine the level of stability of the in-pit dump by analyzing the current in-pit dump stability based on the value of the safety factor (FS) and the probability of failure (PoF) The study shows that the slope is in the safe category (stable slope) in the range of pof values 0 – 1%, marginal slope 1 – 12%, and unstable slope above 12%.