Microcracks can be distinguished from the other texture of rock by filling them with a fluorescent substance and then observing them under a microscope. Microcracks and pores in rock samples were filled with methylmetaacrylate mixed with fluorescent paint and red dye and then microscopically visualized under ultraviolet ray. The methylmetaacrylate almost completely filled the cracks and pore in the samples. Since the limits of detection vary directly with the intensity of ultraviolet ray, we designed a fiber optic ultraviolet lamp. We tested rock specimens such as weathered granite, sedimentary rock, and specimens damaged by uniaxial compression.
Microcracks can also be distinguished from rock specimens by coating the specimens with fluorescent resin, and then recording images by a CCD camera. The images can then be processed in several steps, including image sharpening, extraction of microcracks, and line thinning. The total length of microcracks per square millimeter'in samples of weathered granites from Mount Rokko was measured by this method, and results showed good agreement with the porosity determined by the JIS A1110 method.

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During the hydrofracturing experiments, the monitoring of Acoustic Emisson (AE) accompanied by the pressurized water injection were carried out in order to locate the hydrofractures. Eight piezoelectric transducers were used for the monitoring. Four hydrofracturing experiments were carried out in two boreholes (HC-1 and HC-2).
During the hydraulic fracturing, hydrofractures made a downward crack growth from the hydrofracture boreholes.
In the first injection of HC-1, a number of AE events were located in the coal seam (T3). So, the first injection was effective to the gas drainage from the T3 seam. In the second injection of HC-1, AE events distributed in the region surrounding the area where AE in the first injection were located.
AE hypocenters' distributions in the HC-1 injections were fractal, and fractal dimensions in the first and the second injections were 2.23 and 2.87, respectively. These results revealed that the hydrofractures in the first and the second injections were planer fractures and spatial fractures, respectively. And, the plane of the AE hypocenters' distribution in the rst injection was approximately perpendicular to the in-situ minimum principal stress.
In the hydrofracturing in the HC-2, the number of AE events was few due to the leak of the injected water.
AE hypocenters' distribution in the HC-2 injections were also fractal, and fractal dimensions in the first and the second injections were 2.65 and 1.47, respectively. These results revealed that the hydrofractures in the first and the second injections were spatial fractures and lineal fractures.

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This report describes a calculation method for mine ventilation networks with a nodal head method.
The generalized equations and calculation methods for solving a steady-state mine ventilation network have been written to clear the algorism of a computer program.
The use of the modified Choleski's decomposition algorism has an advantage of rapid convergence to solve the linear system for the pressure corrections of nodes consisting of a symmetric matrix.
The four examples of the mine ventilation networks, of which the total numbers of the nordes N are 8, 14, 51 and 141 respectively, were calculated with a personal computer (640KB, MS-DOS system). As the convergence criterion, it was employed that the maximum tolerance of the summed flow-rates in continuity at each node is less than 0.1 m³ /min. Under the condition that the pressure of the main fan is kept constant and the acceleration constant for convergence is taken 1.4, the numbers of the iteration until the convergence are nearly 13 for each example. The CPU times of an iteration are roughly in proportion to N^3/2.

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In order to acquire fundamental data on the characteristics of open fires in inclined galleries and the change in ventilation characteristics caused by the fire, a series of experiments have been carried out, using two types of model gallery.
The results of the investigation are summarized as follows;
(1) The effect of the inclination of the gallery on the spread rate of the timber fire was quantitatively clarified in both cases of upward and downward spread of the fire.
(2) Buoyancy effects created by the fire in a inclined gallery contributes to reducing the pressure loss of ventilation in case of ascensional ventilation and to increasing it in case of descensional ventilation.
(3) A method is proposed for estimating the fire spread rate and the fire zone length, the variation of ventilation cased by fire and the effect of the inclination of the gallery being taken into consideration.

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The authors conducted the monitoring of the inside temperature of a retained coal pillar at a certain coal mine for the purpose of early detection of spontaneous combustion of coal. The thermometers placed in steel pipes are inserted into the coal every about 20m.
The results shows there are some correlations between fire ratio and the monitored temperature. We found that the temperature monitoring is one of the method to help daily gas sampling and analyses. Especially the temperature monitoring is effective for the evaluation of the treatment for spontaneous heating of coal.
For the monitoring methods, the sampling interval is required only several times everyday, but flexible interval setting function is recommended for transmitting equipment in case of abnormal situation. The distance of each measuring point is roughly 10-20 m initially, but after monitoring some days, the distance must be reconsidered with the results of monitoring and gas analyses.

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The flotation of-10μm diameter hematite particles using dodecyltrimethylammonium bromide (DTAB) was carried out at various pH in the presence of 1×10^-3 mol·dm^-3 KNO₃ as a supporting electrolyte. The adsorption density of dodecyltrimethylammonium ions (DTA⁺) and zeta potential were incorporated in order to analyze the flotation results. The results obtained are summarized as follows.
1. The adsorption density of DTA⁺ increases linearly with DTAB equilibrium concentration in the range of 1×10^-4 to 1×10^-2 mol·drri^-3 at various pH values, such as 5, 7.4, 9, 10 and 11. This behavior is similar to that of quartz-DTAB system at pH 5. The higher the pH, the larger the adsorption density at a given DTAB concentration.
2. The free energy change of specific adsorption, ΔGsp, of DTA⁺ on hematite, calculated at isoelectric points by using Stern-Langmuir adsorption isotherm, was obtained to be-4.4-5 kcal·mol^-1 in the range of pH 7-11. These values of ΔGsp are close in magnitude to those of quartz-DTAB system at pH 5 and 7.4.
3. Flotation recovery of more than 90% is achieved at 2% surface coverage (θ) of DTA⁺ at pH 7.4 and 10. The floatability decreases when θ reaches 4-5 and 30% at pH 7.4 and 10, respectively.
4. No steady flotation is obtained at pH 5, where hematite is positively charged, in spite of the fact that DTA⁺ adsorption (θ-5%) takes place.

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In the previous report, the authors considered the leaching mechanism of chalcopyrite concentrate by Thiobacillus ferrooxidans, and pointed out that leaching rate was mainly controlled by the deposition of elemental sulphur on the mineral surface. In this report, the effect of the coexistence of Thiobacillus thiooxidans, whose energy source is elemental sulphur, with Thiobacillus ferrooxidans on the leaching of a chalcopyrite concentrate was investigated.
During the culture of both species the relation between the surface tension of the culture medium and cell number was examined, and the phospholipid which is one of the extracellular substances in the culture of both microorganisms were qualitatively analyzed by thin layer chromatography.
The leaching efficiency of a chalcopyrite was conspicuously improved by the coexistence of Thiobacillus thiooxidans with Thiobacillus ferrooxidans. The results indicated that in order to make efficient the leaching of chalcopyrite concentrate, it is necessary that the reactions of equations (1) to (3) or (4) mentioned in the text must consecutively proceed. However, the initially high leaching rate of chalcopyrite did not continue to the complete disiolution of chalcopyrite. The reason is that the growth of Thiobacillus thiooxidans was depressed by the increase of ferrous ion concentration, and that it became impossible to keep the sequence in the above mentioned reactions. Accordingly it is indicated that in order to improve further the efficiency of leaching it is necessary to artificially control the chemical constituents of the leaching solution. As the cell number increased, the surface tension of the culture medium decreased. Phosphatidylethanolamine and phosphatidylglycerol were detected as phospholipid. The phospholipid is polar-nonpolar substance, accordingly these extracellular substances would affect the leaching rate.

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The leaching rate of manganese nodules with sulfuric acid was studied. High grade manganese nodules were crushed to minus 200 mesh, and treated to extract metals under the conditions, where pulp density was 50g/l, sulfuric acid concentration ranged from 0.5 to 3 mol/l, and temperature from 25 to 90°., The results were summarized as below: 1) the percentage of extraction of Mn was less than 5% even when Cu was completely leached out; 2) the leaching of Cu and Ni largely depended on leaching temperature, while the leaching of Fe and Co depend upon sulfuric acid concentration; 3) the leaching rate was expressed by a logarithmic function.

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