Dielectrophoresis has been studied by many researchers in various areas for separating particles according to their electrical polarization properties. Lin et al. recently provided the separation of minerals in high gradient electric field. More detailed research work is needed in the field of solid-solid separation. In this study, at first, the time dependent forces and areas for the captures of a dielectric and a conducting sphere, on a dielectric matrix (sphere-shape) were predicted by the equation derived by Jones et al. Next, the dielectrophoretic separator which contained the matrices of plates fixed with glass spheres between copper electrodes to produce high gradient electric field was constructed. Using the above equipment, capture rates of particles of different materials were examined and found to agree well with the predicted ones. The removal of solid particles from oils of low dielectric constant and conductivity, such as kerosene, would be effective using high-gradient, highintensity dielectrophoretic separator. The conducting particles were mainly captured on the area of the matrices which was perpendicular to the direction of the electric field and its capture rate was independent on the employed alcohol concentration in kerosene. In the solvent of 40% iso-propanol concentration in kerosene, very fine metallic particles (5μm palladium) could be separated from quartz particles (5μm).

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In order to contribute safety secondary mining of one of pillars in Kamaishi mine, stress and vertical displacement changes in the pillar were monitored at two points during the recovery of the pillar for about 560 days until the secondary mining was almost completed.
Two-dimensional stress change in the vertical cross-section was measured by using a pressure cell with eight strain gauges glued around inner wall of the cell, and the vertical pillar displacement was measured with a dial gauge between two rock bolts through a vertical rod.
Main results obtained in this study are summarized as follows;
1) From the measurement of stress change in the pillar, it was concluded that the pillar is still stable during the secondary mining, which was consistent with other measurements carried out at the same time.
2) The behaviour of the stress and vertical displacement changes in the pillar was quite different between two measuring points. This seems to be caused by the complexity of geology and geometry around the pillar, discontinuities and directions of absolute rock stresses.
3) As the large blasting more than 450 m away from the pillar affected the stress in the pillar, it is suggested that the pillars in the mine support rock pressure in collaboration.
4) The vertical displacement in the pillar was less sensitive to the mining excavations in comparison with stress change.

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Some experiments which were assumed abnormal blastings with different bore-hole conditions in coal mine were carried out using iron cannon and observed the explosion flash and sparks generated by blastings. Conclusions are briefly summarized as follows;
1) As the blasting without tamping generate the largest explosion flash and sparks, the most dangerous bore-hole condition for methane-air mixture ignition is blasting without tamping.
2) Coal dust which cover the cartridges reduce the explosion flash and sparks. Coal dust may have explosion flash reducing effect in blasting.
3) If there are coal dust between cartridges in bore-hole, the sparks are generated more than normal blastingwithout coal dust.
4) The important ignition factor for methane-air mixture is considered sparks which are sprayed more widely than explosion flash.
5) Depth of bore-hole and length of charge and tamping have closely relation each other with restraining the explosion flash and sparks which exhaust from bore-hole.

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An analysis considered shock wave was carried out for the braking characteristics of pneumatic capsule in the pipeline with the closed end. In this analysis, equation of motion, equation of continuity and energy equation were used, and the relation between the front and the rear of the shock wave is connected by Rankine-Hugoniot relation. Moreover, the calculation used the polytropic change in stead of the energy equation is also carried out for the purpose of comparison of the analytical methods. The obtained results are summarized as follows;
(1) The discontinuous pressure variations appeared in the experiments were approximated by the analysis considered the shock wave.
(2) The capsule behavior in the pipeline was simulated best by the analysis based on the polytropic change (n=1.20). However, as the shock wave is not considered in this analysis, the discontinuous pressure variations in the experiments could not be simulated.

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The purposes of the present work are to develop a method of numerical simulation for an estimate of flow characteristics of two-phase flow systems in transitional and steady conditions and to obtain designing data and operational conditions for the air-lift system of deep sea mining.
Finite difference equations for the numerical simulation were derived by integration of the partial differentialequations represented by the drift flux model for two-phase gas-liquid flow over the control volume.The method of the numerical procedure for solving the finite difference equations is based on the so-called SIMPLER algorithm proposed by Patankar.
To prove the present numerical procedure, calculations were compared with experimental results which had been obtained with the air-lift pump constructed in 200m depth vertical tank at National Research Institute for Pollution and Resources. Furthermore the method developed in this paper were applied to the estimations of lifting characteristics of water with large scale air-lift pumps of 2000m and 5000m in depth.

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It is not clear that the surface properties of silicate minerals, such as zeta-potential, flocculation dispersion characteristics and floatability, are influenced by acid pretreatment.
In this paper, the surface property changes of quartz, albite and forsterite which show the typical changes among some silicate minerals with HCl treatment and aging time in the water are investigated.
The results obtained are summarized as follows.
(1) Results of zeta-potential measurement showed that:
a) Quartz-water system could be regarded as a system without specifically adsorbed ions.
b) In albite-water system, the first hydroxy complexes of multivalent cations which are dissolved from the mineral surface could re-adsorb onto the mineral surface.
c) In forsterite-water system, the readsorption of the complexes and changes in the surface structure of the mineral by acid pretreatment could considerably affect the zeta-potential.
(2) Flocculation dispersion characteristics depends dominantly on the absolute value of zeta-potential, that is, on the electrostatic interaction among mineral particles in solution regardless of the causes for the potential generation.
(3) Flotation behavior of quartz and albite with. DAC as a collector could be explained in terms of its electrostatic adsorption on their surfaces. In the case of forsterite, additional factors such as crystallinity and smoothness of mineral surface must be considered. That is, the increasing degree of perfection and homogeneity in surface structure of the mineral by acid pretreatment has a tendency to enhance its floatability.

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The effect of the cooling condition of ferro nickel slag melts on retained glass and crystalline phases (enstatite, forsterite, cristobalite) has been discussed.
Commercial ferro nickel slags were classified into two groups; one (slag A, B, C) was located the composition of the olivine (forsterite) primary phase field and the other (slag D)was the eutectic field between pyroxene (enstatite) and olivine in the FeO-MgO-SiO₂system.
The critical cooling rates for glass forming determined directly from the CCT diagrams were in the range of 120 to 20°C/sec and those were dependent on the content of SiO₂as a network former. Forsterite, enstatite, and ristobalite crystallized from all of the ferro nickel slags in that order with decreasing the continuous cooling rate. The first crystalline phase at isothermal heat treatment from the slag A, B, C was forsterite, while those of the slag D were forsterite and enstatite. Enstatite and cristobalite gradually crystallized with the holding time at this treatment.
In addition, the possibility of alkali-aggregate reaction were evaluated by the chemical test, ASTMC289 for the as-received and the heat-treated slags.

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A study on fluid inclusions in quartz and cassiterite from the Huanuni mine in the western part of Bolivia was carried out.
Secondary inclusions along a healed crak show a wide range of filling temperatures but a narrow range of salinities. This would suggest that inclusions were trapped from similar solution in different gas/liquid ratios, due mainly to boiling of the ore forming fluid.
The mode of occurrence of the fluid inclusions indicate that the fluid boiled frequentely at all stages of mineral deposition. Since the lowest filling temperature of those inclusions would be close to the trapping temperature, we conclude that the forming temperatures in the early and late vein stages were about 350°and 100°, respectively.
The boiling under conditions of super saturation, also would cause the profuse deposition of fine grain minerals at Huanuni mine.

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