Rock excavation tests were carried out at elevated, temperature with wedge bit to clarify the fracture mechanism of hot rock for the development of geothermal energy. It was proved that the Ioad required to create a shear crack and the crater shape by wedge penetration agreed well with the theoretical prediction developed when sandy tuff and andesite were used, while tensile cracks were initiated rather than shear crack for marble at more than 200°C which was substantiated by both experiments and theory.
Rock cutting tests were also performed with gear cutter and disk cutter using the linear cutter apparatus equipped with electric furnace at 200°C, 400°C and 600°C. During the experiments the load on the cutter was kept at 500kg and crater depth and tangential cutter force were measured. The crater shape was compared with the theoretical fracture paths developed by wedge bit penetration and close agreement was obtained between them.

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A sonic method is a useful tool for inspecting the condition of a rock in-site.
In the first phase of this study, two kinds of rocks, namely “KITAGI” granite and “IZUMI” sandstone, were loaded axially by using a stiff loading machine, and the propagation velocity of longitudinal wave, AE (Acoustic Emission) count rates and the strains of test pieces were measured throughout the entire stress condition up.to the breakage.
In the second phase of this study, in order to discuss the source parameters concerning the microfracture produced in rocks, the wave analysis for the AE signals was performed by using the dislocation model.
In the third phase of this study, the change in the propagation velocity due to the progress of the breakage in rocks were analysed by using a theoretical model.
The main results obtained in these studies can be summarised as follows. The change in the propagation velocity due to the progress of the breakage in rocks has been much influenced by the shape (the aspect ratio) of microcracks produced in rocks by microfracturing. Consequently, it may be concluded that the sonic monitoring of a rock mass by watching only the propagation velocity is not enough to inspect the progress of the breakage in rocks in-situ.

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In this paper, the authors examined the pressure loss of non-Newtonian fluids flow between parallel plates and analyzed theoretically the critical reynolds number in that condition.
The authors also discussed the critical Reynolds number and the relationship between the friction factor and the Reynolds number.
Basing on the stability parameter z (i. e. Eq. 10) and the critical value of that parameter z_c (i. e. Eq. 12), the theoretical critical Reynolds number of non-Newtonian fluids flow between parallel plates were obtained as follows:
for Bingham plastic fluids
N_ReBC=ρ(4H) V_m/μ_B=2240/3 (2+a_c) ²
N_He=35840a_c/(1-a_c) ⁴where, a_c=τ_y/τ₁₀
for pseudo-plastic fluid
N_RePC=12/4^η (η/2η+1)η·ρ(4H) ^ηV_m^2-η/μ_p=6720 (η+1) ²/(2η+1) ²
As the comparison of the experimental results with the calculated values, it became known that the theoretical values were enough agreement with the experimental values of the critical Reynolds number of non-Newtonian fluids flow between parallel plates.

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In order to develop a mathematical model describing the continuous flotation process adequately some comparative tests were carried out between semi-batch and continuous flotation in the laboratory-scale free-flow flotation machines using the chalcopyrite ore produced in Kishu mine.
The procedures of the semi-batch tests were standardized.
The results indicated that the pulp level or the froth depth had a significant effect on the flotation rates of the minerals and water. In the range of the flotation conditions employed the flotation rate of the minerals could be related univalently to that of water. So the latter was used as one of the criteria of comparison between semi-batch and continuous flotation.
The process model was made assuming that flotation process is a first order reaction and the rate constants are distributed discretely in a few points (2-4), and that the flow characteristics of the flotation machine could be described by the back flow model as reported in another paper of the authors,
Continuous flotation experiments were carried out. Model simulation of continuous flotation was also carried out using the data obtained in the semi-batch tests, and the simulation results were good approximation to the experimental results.
Consequently it was concluded that the process model could describe precisely enough the flotation hebavior of the chalcopyrite ore in the laboratory-scale flotation machines.

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Potential measurements of the white metal-NH3-H2O suspension system at 70°C revealed that the suspension potential in an alkaline region was lower than the potential for the acidic Cu₂+/Cu° of the sulfate system.
A cylindrical galvanic cell (14cm I. D.) was then constructed; it consisted of the negative electrode system (1.5 1, the upper half of the cell) of an ammonia-alkaline suspension of pulverized white metal with an agitator, a negative electrode (a Pt net), electrodes for pH and potential measurements, etc., the positive electrode system (0.3 1, the lower half) with a copper plate electrode (the bottom of the cell) and sulfuric acidic cupric solution as the electrolyte, and a membrane horizontally separating these systems. While maintaining the temperature at about 70°C, both electrodes were short-circuited through an ammeter, thus the electrolysis was carried out and copper was deposited on the positive electrode without an external power supply.
After improvements of electrolytic conditions, especially the composition of electrolyte solutions, the short-circuit current amounted to about 1 A/dm2. The dissolved (oxidized) amount of copper in the white metal was 81% and that of sulphur was 64%, after a run using 100g of white metal for 94 hours. The current efficiency for the positive electrode was 85-100%.
Data of the variations of composition of solutions and residues during the electrolysis were presented. The anodic reactions taking place in the negative electrode system of the white metal-suspension and the material balance of the electrolysis were discussed in correlation to the quantity of electricity flowed from the positive electrode to the negative electrode.

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Cr (VI) in sulfuric acid solutions was reduced with activated carbons (initial solution; 2.5×10^-3 mol/500ml as K₂Cr₂O₇). Reduction rate of Cr (VI) and chemisorption of Cr (total) varied considerably with the various types of activated carbons. The results obtained in these experiments can be summarized as follows;
1) Remaining Cr (VI) and Cr (total) decreased rapidly in the initial reaction period (several minutes). The reduction rate of Cr (VI) with the activated carbons decreased gradually in the course of the reaction, while the remaining Cr (total) stayed constant.
2) Remaining Cr (VI) decreased with an increase in reaction temperature, and with an increase in the amount of activated carbons, and was propotional to the amount of fine sized particles. However, there was no detectable variation with increasing of Cr (III)/Cr (VI) mole ratio in the initial solution.
3) Remaining Cr (total) reached a minimum value at pH 3-4 in the reaction solutions (initial pH; about 2.5). From calculation of all the chemical species in the initial chromate-dichromate solution, it was considered that the predominant species on activated carbons were HCrO₄-and Cr₂O₇^2-.
4) The following eouation can be suonosed for the reduction of aqueous dichromate solutions with activated carbons. 2Cr₂O₇^2-+3C+16H+→4Cr³⁺+8H₂O+3CO₂

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