Vol. 23 No. 2 (2020): INDONESIAN MINING JOURNAL, Vol. 23 No. 2, October 2020

The law Number 4 Year 2009 concerning mineral and coal mining firmly emphasizes that all mining operations in this country must be carried out by applying good mining practices.  In order to reduce mine accidents, a good mining design must be prepared by providing an accurate geotechnical investigation.  Referring to such a statement, a slope stability research using the  cuckoo search (CS) had been conducted.  compared to the grid search – a conventional method that takes a longer time to locate the slip surface, the CS is a very fast and efficient method. A paper presenting in this current journal relates to the above issues.

The main point of the delay effect of mud loading to the open pit design relates to coal production target.  Such the delay results in hindering the mining sequence pattern which forced changes in plans, designs, and decrease of coal production.  Minex software is then used to simulate the alternative of redesign the mining sequence pattern. The study found that the delay in mud loading process is due to the external and internal factors as stated in one of the papers published in this issue. Still related to the coal mining, one paper is also discussed about coal mining. The topic concerns with underground coal gassification notably to predict the surface subsidence by making a simulation and model.  Level of surface subsidence risk and effect of high temperatures due to the UCG activities can be determined.

Two last papers within this issues relate to mineral and coal processing. The former discusses the making of synthetic zeolite from a residue of bauxite washing while the later reviews the influence of steam drying process on combustion behavior of Indonesian low-rank coals.  Raw materials for making the synthetic zeolite include the amorphous solids such as meta-kaolin, siliceous earth, coal ash, kimberlitic waste, alumina tri-hydrate [Al(OH)₃], bauxite, and aluminum metal; while steam drying process of the low rank coals (LRCs) has been conducted to produce coal which is comparable with the high rank coal (HRC).