Akihiro Hamanaka

Underground coal gasification (UCG) is a technique to recover coal energy without mining by converting coal into a valuable gas. Model UCG experiments on a laboratory scale were carried out under a low flow rate (6~12 L/min) and a high flow rate (15~30 L/min) with a constant oxygen concentration. During the experiments, the coal temperature was higher and the fracturing events were more active under the high flow rate. Additionally, the gasification efficiency, which means the conversion efficie

Abstract This paper described the use of fly ash for soil amelioration of acidic soils to promote plant growth. In mining sites, acid sulfate soils/rocks, which contain sulfide minerals (e.g. pyrite FeS 2 ), have appeared as a result of overburden excavation. The excessively acidic condition inhibits plant growth due to the dissolution of harmful elements, such as Al, Fe, and Mn. Fly ash, an alkaline byproduct of coal combustion generated in thermal power plants is expected to be adopted to amel

Soil erosion is one of the major environmental problems in open-cut mines in tropical regions. It causes negative impacts including the removal of nutrient-rich topsoil, destroys aquatic habitat, dam and pond siltation, clogs river by deposition of sediment, and causes water pollution in the rehabilitation process. Soil texture is an important factor to affect soil erosion. In this study, artificial rainfall experiment in the laboratory scale was conducted to clarify the mechanism of soil erosio

Underground Coal Gasification (UCG) requires monitoring of the gasification area because the gasification process is invisible and the reaction temperature exceeds 1000 °C. Many fracturing events that occurred due to coal heating can be captured with Acoustic Emission (AE) monitoring technique during UCG. However, the temperature conditions to generate fracturing events during UCG have not yet been clarified. Therefore, the coal heating experiment and small-scale UCG experiment are conducted by

In Indonesia, the adoption of the underground coal mining method is discussed to extend coal production. However, the geological conditions in Indonesia are very weak. In particular, the mechanical properties of the immediate roof/floor in shallow depths are weaker than those of coal. Therefore, the control measures to maintain stability around the developing area should be discussed for safe longwall mining operations. This study discusses the design of safety pillar width in longwall mining un

Soil erosion is one of the major environmental problems in open-cut mines in tropical regions. It causes negative impacts including the removal of nutrient rich topsoil and subsequent reduction of agricultural productivity in the rehabilitation process. Therefore, it is important to predict soil erosion in advance and establish the proper process to minimise the phenomenon for the success of rehabilitation in the disturbed land. Field investigation to understand soil characteristics in rehabilit

Background: The demand for underground space utilization using pipe jacking method is increased especially in the congested urban area. Methods: In the method, the over-cutting area is formed between pipes and surrounding soils in order to smoothly construct underground pipelines. The backfilling materials as a lubricant are injected into the over-cutting area during the constructions in order to reduce the friction resistance and to sustain the surrounding ground against the overburden pressure