Numerical simulations on rock behaviour in case of earthquake for the various model slopes were carried out by using Distinct Element Method, in order to investigate the applicability of static evaluation of slope stability by conventional formula for plane sliding to the discontinuous rock slope such as those of the quarries in the area of Oshima district. Each safety factor calculated by the conventional formula was referred to the existence of slope collapse, which is displayed by the computer simulation, for each model and the followings are found from the investigations:
1) the conventional formula can not sufficiently evaluate the effect, especially in case of earthquake, of the safety increase by reducing slope inclination.
2) however, the evaluation by the conventional formula may be allowable because the underestimation of safety factor by the formula is not so remarkable and it is safety side.

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In this paper, the fracture surface roughness of coal samples from the four coal mines in Hokkaido was measured and analyzed. The main results obtained are summarized as follows:
(1) The surface of the coal fracture is a random surface varying in some places smooth and others jagged. With a measuring length of 18 mm, it is clear that the coal fracture surface roughness varies in the range of 92 170μm. From the results of a goodness-of-fit test, it is clear that the probability density distribution of the coal fracture surface roughness fits the normal distribution.
(2) The results of spectral analysis of the roughness show that the frequency content of the roughness appears widely from low to high. The significant frequency content that represents the character of the coal fracture surface can not be distinguished. The same results are also obtained by calculating the autocorrelation of the roughness.
(3) From the measurement results of the coal fracture surface roughness, a relation has been obtained that the larger the largest fracture width and the standard deviation of the distribution of that fracture's surface roughness is, the greater the methane drainage ratio becomes, although the methane drainage ratio is generally affected by large number of parameters.

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In order to verify the results of sensitivity analysis based on the analytical model introduced by the authors, an experiment have been carried out by using two different types of the oil hydraulic breakers.
The experimental results obtained are summarized as follows.
(1) In the case of the forward stroke of the piston, both pressure in the piston rear-chamber and the accumulator are maintained a higher value with decrease the leakage flow rate of the piston rear-chamber.
(2) As the leakage flow rate of the piston rear-chamber decreases, the supply oil flow rate also decreases, but the blow velocity of the piston and the number of blow increase. As a consequence, the efficiency of the oil hydraulic breaker is improved sharply.
(3) It is confirmed that the results of sensitivity analysis are supported by the experimental results.
(4) It is necessary to design and manufacture an oil hydraulic breaker paying particularly close attention to the spaces between the sliding surfaces related to the piston rear-chamber.

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This paper describes interaction between sulfur-oxidizing bacteria and protozoa in a long time enrichment batch culture. The bacteria, collected from a neutralization plant of the abandoned Matsuo mine, has been cultured in an acidic environment (pH2), using iron-free 9K medium with elemental sulfur. In the culture, we have confirmed protozoa which belongs to Bodo edax, and whose sizes are about 5-15μm in length and 5-10μm in width. To investigate the interaction, time-dependency of the each number is examined under the following conditions: ventilation, air flow rate of 50, 25 cm³·s^-1, shaking with a cycle of 2.2 s^-1, and initial pH value, 1, 2, 3. The results obtained are summarized as follows:
(1) the ratio of protozoa to sulfur-oxidizing bacteria is nearly constant and from 10^-1 to 10^-4 in the enrichment culture;
(2) at initial pH value above 0.6, protozoa can increases, but decreases at the pH value less than 0.6;(3) when there exists protozoa in the enrichment culture, the yield factor of sulfur-oxidizing bacteria growth is about 1/7 of that in the protozoa-free case.

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In order to reveal the effect of grinding aids and size of grinding media on grindability of water-quenched glassy slag of blast furnace, dry fine grinding has been carried out using tumbling and vibrating ball mills. Triethanolamine (TEA) was found to be excellent grinding aid, and the slag was ground most effectively when small amount of TEA was added every 10 hours. In the single ball-size system, it would be effective when balls of large size are changed to balls of small size after some extended grinding. Grinding efficiency can be also improved in single stage grinding using a mixture of 20mm diameter and 5mm diameter balls as well as a single ball-size system of 5mm diameter balls. The reaction between the ground slag and water, by which calcite is formed in the drying process, becomes active with the progress of grinding.

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Two-phase comminution-liberation model is developed to investigate the effects of raw material properties and operating conditions on mineral liberation. To represent the raw material properties, the distribution function on the constituent mineral grain size is proposed by the introduction of run theory.
The simulation results indicate how the mineral grain size and the size of progeny particles after comminution affect mineral liberation. It is also shown that the fractional degree of mineral liberation (FDL), i. e., degree of mineral liberation at a constant particle size, is independent of the reduction ratio, while the shape of FDL curve does not change by the breakage properties and content of valuables.

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Manganese dioxide was precipitated from slightly and strongly acidic solution of manganese sulfate by ozone oxidation at temperatures up to 80°C. The particles were characterized by SEM observation and X-ray diffraction.
Ozone was found to be very effective to produce manganese dioxide even at acid concentration as high as 5.0mol/l.
The size and surface morphology of the particle were strongly affected by acidity and temperature. At pH 2 or 3, the particles were as small as about 0.2μm and had rugged surface. Particles consisted of nearly spherical grains of a size of 1-2μm with smooth surface at 1 or 2mol/l H₂SO₄. The particle surface turned rougher and finally was covered almost uniformly with thin needle-like crystals as the acid concentration increased up to 5.0mol/l. It was observed that the particle had rougher surface as the reaction temperature was raised.
X-ray diffraction analysis showed that γ-MnO₂ was a main reaction product under the conditions excluding pH 3.0 and 5.0mol/l H₂SO₄ at 80°C where α-MnO₂ was detected.
Also, use of ozone was proved to enable us to produce very fine particles of manganese dioxide with discharge behavior comparable to commercial electrolytic manganese dioxide for a battery-active material.

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Aluminothermic reduction of Nb₂O₅ or Nb₂O₅ /ZrO₂ mixture followed by the electron beam melting to produce Nb-1% Zr alloy has been investigated. On the aluminothermic reduction of both Nb₂O₅ and Nb₂O₅/ZrO₂ mixture, 70g and 210g batch tests were carried out to estimate possibility of the production of Nb-Zralloys.
Good seperation of metal from slag was obtained by means of external heat to 873K or internal heat compensation of exothermic reaction between KClO₃ and Al. Zr contents in the Nb-Zr alloys increased with increasing initial Al compounding ratio. The alloy containing Zr of more than 1% was obtained when the mixture of ZrO₂-Nb₂O₅ (20% Zr-80% Nb) was reduced by Al with an excess of 10% over stoichiometric requirement.

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It is well-known that the corrosion and the wear resistance of iron and steel increase in dependence on Cr content. SUS304 stainless steel, having high corrosion resistance, shows the less wear resistance and the less hardenability by heat treatment.
In this study, a chromizing process for SUS304 stainless steel for 3 hours at 700, 800 and 900°C respectively has been investigated by means of disproportionation reaction in molten salt, which contains mainly KCl-BaCl₂-NaF ternary system. Fe-Cr film with the thickness of 20μm was formed on the surface of the specimen after chromizing at 900°C for 3 hours. Consequently, it is evident that some properties of SUS304 stainless steel such as the pitting resistance, the corrosion resistance, the wear resistance, the hardness and so on, would be remarkably improved very much by the formation of Fe-Cr film on the surface.

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A wet silica purification method by precipitation in nonaqueous solvent is studied. This method can be applied in the treatment of resources containing alkali soluble silica. The process consists of three steps. At the first step, silica resource is leached in alkaline solution and filtrated. At the second step, the leach liquor is poured into nonaqueous solvent such as methanol or ethanol, and silica sediment is precipitated. At the third step, the sediment is washed with acid solution. The characteristic of this method is that alkali and nonaqueous solution used in the process can be easily recovered separately by heating at lower temperatures. In this study, diatomaceous earth was employed as the silica resource. It was leached in NaOH solution. By this method, Ba, Ca, Fe, K, Mg, Mn and Sr were removed effectively, but Al, Ti and Na had tendencies to remain in silica. The repeated treatment did not reduce Al and Ti contents effectively. In order to reduce the impurities, alkali leach liquor was pretreated with oxine etc. before the precipitation of silica by methanol. With this process Ti content was reduced effectively. The silica sediment formed in methanol method was the coagurate of spherical particles less than 1μm in diameter.

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Zinc was electrodeposited from synthetic sulfuric acid electrolyte containing ethylene glycol on the aluminum cathode using the insoluble Pb-0.7%Ag anode, and the effect of ethylene glycol on the several factors affecting the energy efficiency for the electrowinning was studied from the standpoint of energy savings in the hydrometallurgical production of Zn. Ethylene glycol added in the concentration from 0 to 0.2mol/l reduced the overall cell voltage by 50mV at the highest, which was resulted from the depolarization of oxygen evolution at the anode. Surface film, formed on the anode and composed of lead dioxide, became more compact and more smooth when the concentration of ethylene glycol increased in the electrolyte.
Ethylene glycol, on the other hand, shifted the cathode potential to less noble direction to reduce the current efficiency for Zn deposition. However, the same phenomenon was observed by adding glue which was usually used to suppress the cathodic depolarization caused by some impurities in the industrial electrowinning of Zn. Therefore, the improvement of energy efficiency can be expected when an amount of glue to be added is partly replaced with ethylene glycol in the electrowinning of Zn.

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After TiAI and TiB₂ compounds were synthesized using the fine powders of titanium, aluminium and boron by the mechanical alloying method, the sintered TiAI-TiB₂ composite materials were prepared at the temperature of 1573 to 1773K under the pressing conditions of 202.7 MPa by HIP method. It was found from X-ray diffraction analysis and an electron microscopic observation that the homogenous sintered composite materials consisting of TiAI, TiAl₃₂ and TiB₂ compounds could be produced by these both methods. Micro-vickers hardness of the composite materials decreased with increasing the temperature of HIP treatment.

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