In field measurements with the Schlumberger method, the section of the data related to the depth of basement shows sometimes a slope of excess 45°C in the VES (Vertical Electrical Sounding) curve.
Though several reasons are believed to account for this phenomenon, here we assume it to be caused by an inclined basement, and calculate the theoretical VES curve for an inclined basement model. Curves displaying a slope of more than 45°C are obtained from those models. To confirm the theoretically calculated results, model experiments using a water tank were carried out. Experimental results are well consistent with the computed VES curves.
Next, a computer program intended for automatic analysis of horizontally multi-layered structures was improved to be applicable to the inclined two-layer case with an arbitrary dip angle of the interface.
This computation procedure was further developed for a horizontally multi-layered, model with an inclined basement, and applied to the data obtained from field measurements. These results show that automatically computed VES curves based on the inclined model can fully explain the field data.

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In the design of underground openings excavated in rock mass for storage of Liquefied Natural Gas (L.N.G.) whose ternperature is -162°C, one of the important problems is the stability of the rock mass around openings at low temperature. This paper presents the results of the theoretical analysis of the plastic zone occurring around underground openings, and the results of an investigation of stability.
For estimating the change over time of the plastic zone around openings, the Finite Element Method (F.E.M.) was used in combination with the No Tension Analysis Method, the Anisotropic Analysis Method and the Crack Analysis Method. And then several factors which have effects upon the plastic zone are discussed.

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There are pnenomena that the atmospheric CO concentrations of sealed areas decrease rapidly compared with other gases concentrations are kept almost unchanged. Then, causes of these phenomena were tried to be resolved. The result clarified that the CO concentration emitted from a coal sample decreased rapidly when the coal sample was wet adequately with no relation to its inherent moisture and kept at an appropriate temperature. However, the CO concentration did not decrease rapidly in such an atmosphere as bacteria were not alive. Therefore, it was clear that the phenomena were attributed to bacteria regardless of coal itself.

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Oil hydraulic rock drills have been used on the field of mining and public works. This paper treats the percussion type rock drill, which is driven by the interaction of a piston and valve. Sensitivity analysis is applied to an investigation of the influence of design parameters on the performance of the oil hydraulic rock drill. It is demonstrated that the effect of leakage from the rear chamber of the piston is more sensitive to the performance. For the purpose of optimum design the influence of the construction of the oil hydraulic rock drill is also indicated choosing dimensions of the piston as variable.

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In the previous papers, it was reported that a pilot plant was constructed to test for recovery of pure kaoline with a closed water recycling system, using kaoline ore of the Minami-shiraoi mine, Hokkaido.
In the present paper, the authors carried out experiments to compare with the results between the continous operations of an open circuit system and operations of approximately 50% and 90% recycling ratio with a closed circuit system. The changes of the accumulated materials in the closed circuit system and the influence of these accumulations on the performance of the process were measured and examined.
Due to the reuse of the waste water in recycling, solid particles and materials in solution accumulated in the recycling water as well as in the plant water, and these increased in proportion to the recycling ratio.
On the other hand, when the amount of the accumulations exceeded the permissible limit value, the performance of the equipments was markedly lowered. This result indicated that it was necessary to estimate the process of the passage of time in accumulation of the materials and their extent, and to find the best recycling ratio and the optimum operating condition.
Investigation on the simulation of the recycling system will be the most reasonable to consider the optimum operating condition. This report proposes the simple models of the mass balance of materials and the flow pattern of the flows in each apparatus. A simulation program of total system has been made by using those models.
The calculated results approximated to those of the survey. From this fact, this simulation program expresses well the behavior of the materials in a recycling system.

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It was found that there are enormous reserves of sericite in the Shiang-Yang area of Taiwan. Due to the lack of beneficiation technology, these resources have not been effectively utilized.
A series of investigations, including mineral identification and analysis, attrition grinding, flotation, and settling on the sample from the outcrops gave rise to the following results:
1. The outcrop samples are of flake or clay-like shape and the color of them vary from white. grey to dark grey.
2. The sericite are consists of sericite, pyrophyllite and quartz, and is accompanied by chlorite, calcite and pyrite as impurities. It also contains tra amount of copper, lead, silver and arsenic, etc.
3. Because the sericite ore is weakly bonded, it can be pulverized through the attrition grinding to give the particle size required for flotation operation.
4. The flotation behaviors of pyrophyllite, pyrite, sericite and quartz have been well understood. These minerals can be effectively separated by means of flotation.
5. The K₂O contents of the sericite can be upgraded to above 8% by means of dispersion followed by settling.
6. The flotation and settling procedures can obtain the following products: sericite which meets the industrial welding specification requirement, pyrophyllite suitable for refractory.

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A Kinetic study of pyrite oxidation by ferric sulfate in absence of oxygen and bacteria is described. The effects of reactor agitation, ferric, ferrous and hydrogen ion concentration and reaction temperature on the oxidation rate were examined. All experiments were carried out isothermally in a well-stirred batch reactor. The kinetic data were used to develop kinetic rate equations. The results are summarized below.
Pyrite oxidation is decribed by following two reactions occuring in succession.(1) Ferric ions react with FeS₂ to form ferrous ions and a sulfur product.(2) The elemental sulfur is oxidized to sulfate by ferric ions. Kinetic rate equations were obtained for the two reactions, (1) and (2), respectively.
The oxidation rate of the reaction (1) was found to be independent of pH. On the other hand, that of the reaction (2) increased with increasing pH. So sulfate is formed more than elemental sulfur with increasing pH.
The activation energies for reactions (1) and (2) were 47KJ/mol and 83KJ/mol, respectively. Because of the difference between the activation energies, sulfate is formed more than elemental sulfur with an increase in temperature.

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