Electrokinetic remediation is an emerging technology that can be used to remove contaminants from heterogeneous fine-grained soils in situ. Contaminants in the subsurface are removed by the application of a low level direct current electric field across the contaminated soil. The primary contaminant transport and removal mechanisms are electroosmotic advection and ionic migration. However, there are many complex physicochemical reactions occurring simultaneously during the process that may enhance or retard the cleanup process. Nevertheless, the feasibility of the process has been demonstrated by results obtained from many bench scale and large scale laboratory and pilot scale field experiments performed on various soils.
This paper reviews the fundamental concepts and the practical aspects of the technology. Laboratory studies of the technique are outlined and major factors affecting the removal process are examined. Enhancement techniques and hybrid process are considered and examples of field trials are described.

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In order to extract promising areas of mineral resources, many studies have used stochastic or statistical methods such as weight of evidence, fuzzy logic and neural network. With the development of computers, the GIS (geographic information system), which is effective for spatial analysis of different kinds of data in an area, has been available to process enormous quantities of exploration data through the use of a personal computer.
The Hokuroku district covering a 31 km × 44 km area in northern Akita, Japan, was chosen as the site for a case study. This area is famous for having many kuroko deposits generated in Miocene, a kind of volcanic massive sulfide deposits. For the study area, nine kinds of exploration indexes regarding geological features, deposits and geochemical data were examined in combination with the deposit formation and geophysical data covering the study area, such as gravity, airborne magnetic, and lineament density data. Initially, 12 kinds of exploration indexes were digitized in order to handle with the GIS and to construct a spatial database. The area was gridded at 1km spacing, and multiple regression analysis and variable increase method were used to estimate the basement structure and the deposit positions as well as to extract promising exploration areas in the horizontal plane.
The regression function proved to be analytically useful, and seven effective kinds of exploration indexes were specified. In particular, two kinds of regression coefficients were large. These included vein type deposits, in which the host rock is in the shape of hanging wall formations of mineralized stratum (K10) and the alteration index (K12). Based on the multiple regression analysis, 80 % of all the ore bodies may be discovered in the 27.3 % portions of the study area, which is considered to be conspicuously efficient as compared with the index overlay model.

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A new recycling system by using paper debris and polymer has been developed for high water-content mud such as bed materials in the river and lake, and construction sludge. The new recycling system proposed in this study consists of two steps. In the first step, the paper debris are added for controlling water content of mud and strengthening the bonding force between mud clusters. In the second step, polymer materials are added to increase the bonding force of mud particles in the cluster. By using this system, 200- 500% water-content mud has been modified to landfill materials by 20-30 minutes mixing process.
The unconfined and triaxial compression tests were carried out to examine the strength of the recycled soils. It was confirmed through the tests that the failure strain and residual strength of the recycled soils produced by the new system are much larger than those of recycled soils produced by the conventional method. Furthermore, the transformation coefficient of the recycled soils is close to the one of the ordinary soils. Therefore, it can be concluded that the recycled soils produced by the new system are much more suitable for landfill materials than the recycled soils produced by the conventional method.

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Liquid products produced in a hot water drying (HWD) process of Beluga low rank coal were characterized by GC/MS, HPLC, GPC, TOC measurement and cyclic voltammetry. The Beluga coal was treated at three different temperatures, namely 270, 300 and 330°C. The ability of the liquid products to reduce Cr(VI) was investigated by analyzing the solution containing the liquid and Cr(VI), using Fluorescence Spectrometry. With increasing treatment temperature TOC concentration of the liquid products became larger. The liquid product at 270°C contained acetic acid, acetic acid-methyl ester and oligomer. The oligomer mass was found to be 1,600∼3,400. The liquid product at 300 and 330°C contained catechol and phenol, and the liquid product at 330°C contain more catechol groups. The reduction behavior of both liquids obtained above 300°C was similar to that of catechol in cyclic voltammetry.
All liquid products reduced the Cr(VI) to Cr(III), and their reduction ability became stronger with decreasing pH. For a solution containing high Cr(VI) concentration (2.7x10^-2 mol/dm³) the liquid obtained at 330°C successfully reduced Cr(VI) to a concentration below the allowed level at pH 2. It was found by fluorescence spectroscopy that Cr(VI) was reduced due to catechol groups in the liquid products.

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At Kakkonda geothermal plant in Iwate Prefecture, the geothermal water after the separation of vapor is rejected underground through the rejection well because it contains arsenic (ca.3.4 mg / l). Arsenic exists mostly as arsenite (As (III)) or arsenate (As (V)) in natural water. As(III) is more toxic than As(V), and As(V) is removed more effectively than As(III). The oxidation of As (III) to As (V) is necessary to achieve effective removal of arsenic.
In this study the speciation of arsenic in the geothermal water was carried out and the effects of several parameters such as pH, temperature and stirring time on the oxidation of As (III) in the geothermal water were investigated. In addition, the effect of oxidation of As(III) on the arsenic removal by the coprecipitation using Fe(III) was examined. Results obtained are summarized as follows;
1) Arsenic was present as As(III) in the geothermal water after the separation from the vapor.
2) As(III) concentration decreased gradually with time at 80 °C while total concentration of arsenic did not changed, indicating the oxidation of As(III) to As(V). The oxidation rate decreased with decrease in temperature down to 30 °C.
3) The pH adjustment to over natural pH (8.4) enhanced the oxidation rate at 80 °C
4) Prior to the coprecipitation treatment using Fe(III), adjusting pH values to more than 10 followed by the stirring for several minutes improved the removal of arsenic from the geothermal water. It was due to effective oxidation of As(III) to As(V).

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塩酸溶液からのチタン(IV) の抽出がDEHPA( ジ - 2 - エチルヘキシル　リン酸) の灯油またはベンゼン溶液の使用により種々の条件で検討された。有桟相への抽出物が赤外線のスペクトルの測定により調べられた。その結果水溶液相中の塩酸濃度が3mol 以下(低酸濃度)では陽イオン交換反応で，3mol 以上(高酸濃度)では溶媒和反応でそれぞれDEHPA によりチタン(IV)が抽出されることがわかった。低酸濃度ではDEHPA が過剰に存在する時は単量体化学種が生成し，チタン濃度が高くなると多量体化学種が生起した。さらに非平衡状態での抽出の検討が加えられ，低酸濃度でも高酸濃度でもチタン(IV) の抽出はS_N1 桟構により進行することが確かめられた。

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There are many sites where opencut mining operations have developed long highwalls that have been abandoned due to the economic limits of surface mining technology. Highwall mining is a technique utilized after the opencut portion of a coal seam has been mined, sometimes prior to the introduction of full-scale underground mining. In the highwall mining, the coal seam is mined by remotely operated equipment such as an auger or a continuous miner. However, a large amount of coal tends to remain isolated and undeveloped as pillars due to mining operations performed by the auger or the continuous miner. Major issues are less coal recovery and highwall instability due to pillar and roof failures of the extraction holes.
Where the conventional opencut mining is difficult or impossible in a small-scale mine due to uneconomical stripping ratio, the highwall mining systems could be applied to this site. After making a small pit, the mining operation starts from the outcrop with less environmental disturbance.
This paper describes highwall mining systems and their problems and also proposes new mining systems to increase the coal recovery from final highwalls with using conventional underground mining methods and equipment.

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Several kinds of in-situ tests on groundwater were carried out in order to know the characteristics of groundwater flow in old coal field. The following results were obtained. The coal mining caused a loosened zone in the ground, an increase of permeability, and change in groundwater flow. The coefficient of permeability of ground in loosened zone was about 10^-2 ∼ 10^-4 cm / s, and it was about 100 ∼ 1,000 times that of non-loosened zone. It was found that the faults in ground sometimes behave like a permeable zone or impermeable zone. Therefore, we have to properly estimate the properties of fault in ground.

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Ishikari coal field is the gassiest coal field in Japan. There is no operating coal mine in this coal field, but there are many closed coal mines. From these coal mines, methane has been emitted into the atmosphere. This is a significant problem for global warming because global warming potential of methane is twenty one times as much as that of carbon dioxide. Therefore, we plan to use the methane emitted from the closed coal mines as fuel for a small scale generator and inject the exhaust generated by the egines of electric generation into the gob area of the closed coal mines. Injected carbon dioxide is absorbed by coal remaining in the gob area and replaces methane absorbed on coal surface. Fig.1 shows the outline of the utilization of CMM and CO₂ injection system.
In order to make it clear, some investigations have been carried out at Akabira Mine and laboratory tests have been carried out at Hokkaido University. The subujects of these investigations and tests are shown as follows;
(1) Investigation on gas potential of Akabira Mine
(2) Methane emission rate from the shafts into atmosphere
(3) Communication among shafts and gas potential of each shaft
(4) Estimation of methane production from the New Akabira Mine
From the results of these investigation and tests, there is no different between the measurement results and estimation results. Therefore, we think that above investigation and tests are very useful methods for evaluation and estimation of the recovery CSM from the abandoned coal mine.

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This model project had been carried out since 1997 Japanese fiscal year (JFY) to 2001 JFY by the subsidy from New Energy and Industrial Technology Development Organization (NEDO) in order to demonstrate the effect of the new coal preparation technology system on de-ashing and de-sulfurizing of high-sulfur raw coal. The system consists of "VARI-WAVE" air-pulsated jig, high-shear mixer, flotation cells, tailing thickener, pressure filter, central control facility and so on, with the throughput of 450 thousand ton per annum. The demonstration operation had been conducted since November 2001 to March 2002, at Jinjia Coal Preparation Plant, Panjiang Coal & Electric Power (Group) Co. Ltd., Guizhou Province, People's Republic of China. High sharpness of separation was obtained by "VARI-WAVE" air-pulsated jig owing to the trapezoidal pattern of water pulsation. Flotation of semi-anthracitic coal with low floatability was realized by use of high-shear mixer in advance. Also new type pressure filter has been operated with no trouble. By the demonstration operation, target values (de-sulfurizing ratio, de-ashing ratio and yield) stated in the Basic Agreement signed by Japanese and Chinese governments had been all verified.

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JCOAL and CSIRO commenced a co-operation project on mine gas control in 1997 based on the agreement between Australian and Japanese government. The aim of the project is to develop effective post-mining goaf drainage technology for highly gassy longwall mines. A suitable site in Australia has been identified at Dartbrook in Hunter Valley. Overall scope of the project include field experiments with gas drainage technologies such as long horizontal holes, cross measure holes and surface goaf holes, and other field experiments of tracer gas studies, goaf gas distribution, gas analysis and ventilation monitoring. The project also include computational fluid dynamics modeling of gas flow in goaf environments and 3D visualization of the workings and gas drainage holes.
Dartbrook Colliery is one of the gassiest mines in Australia, with longwall goaf gas emissions in the order of 420 to 540 m³/min. The capacity of the post-drainage system designed should be large enough to capture a major proportion of these goaf gas emissions. The susceptibility of the coal seam to spontaneous combustion and large quantities of broken coal left in the goaf compound the gas problem at Dartbrook. The spontaneous combustion issue demands that oxygen ingress into the goaf should be minimised. Requirement for high goaf gas drainage capacity and the need to prevent oxygen ingress into the goaf are contradictory to one another and should be considered during design and implementation of goaf gas drainage system.
This report presents the details and results of the joint R & D project.

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