In this study, the physical and mechanical properties of the specimen were examined at first in connection with the electrical disintegrating drilling and then some experiments were carried out to determine how effectively the electrical disintegrating drilling can be used in comparison with a conventional rotary drilling. The specimen used throughout this study was the cement mortar. The main results obtained can be summarized as follows:
1) Both the strength and the Young's modulus of the cement mortar decreased greatly by cooling it rapidly after it had been heated over 300°C.
2) When the voltage applied on the bit was larger than 750V, the effect of electrical disintegration appeared remarkably and the rate of penetration in these cases reached 1.7-2.0 times larger than that obtained by a conventional rotary drilling under the identical condition.
3) For this method of drilling, the bit having a self-sharpening action was considered to be more effective than the cutting type one.
4) To get the effective drilling with the tri-cone bit, the electrical energy beyond 3 KWS had to be spent per unit length of penetration.

抄録全体を表示

The work described here was conducted to investigate the possibility of the ignition of firedamp by rubbing friction between steel and rock. The apparatus used was almost as similar as that in the study made by Thomas and Datey. Coal, brick and sedimentary rocks from various coal measures of Hokkaido were used at about 6.5% methane-air mixture condition in every experiment. The time of rubbing was limited to five minutes.
It was observed that all the ignitions of our tests seemed to have been initiated by the formation of such a heaped hot spot at the end of contact that contained a large amount of molten materials. In rubbing friction the maximum temperature of the contact surface depends on the temperature at which the rock concerned melts and starts to soften. These maximum temperature was measured in addition by means of photo-resister for each rock samples and was estimated to be 1100-1200°C.
The coal did not cause ignition because of the low maximum temperature of the contact surface. lgnition took piace for the softe rrocks such as coaly shale, shale, medium sqndstone of less compressive strength because they were easy to develop a patch of fused rock that is hot enough and large enough to ignite the gas. No ignition occured for the rocks of rich quartz content and of high compressive strength because it was difficult to form the large hot spot on the sliding surface due to the surface hardening at a continuation of rubbing.
In each test the frictional force was also measured by means of torque meter connected to the wheel shaft. There was always a sudden increase of torque just before ignition was obtained.In the rocks which caused no ignition, such change of torque could not be seen.

抄録全体を表示

We suppose that the wave of wire rope for mining exerts remarkable influence upon its various properties and consequently is in danger of causing unexpected obstacles and accidents in service.
This study was carried out to find out this influence experimentally and theoretically. In this study we came to the following conclusions:
1. When the wave of rope has the same direction as the lay of rope, the tensile strength decreases and the true elongation increases and, on the contrary, when the wave-has the opposite direction, the tensile strength increases and the true elongation decreases.
2. The wave of rope has bad influence upon bending fatigue property of wire;ope.
3. The rotating by tension owing to the wave of rope appears to be depended mainly on an early loading. The rotating of rope by tension is arisen practically from both wave and lay of rope. The wave of rope having the same direction as the lay of rope causes the negative rotating by tension and the wave having the opposite direction causes the positive rotating.

抄録全体を表示

In a previous paper on the activation of pyrite by heavy-metallic ions such as Hg²⁺, Ag⁺, Cu²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Ni²⁺ and Co²⁺, it was shown that Hg²⁺, Ag⁺ and Cu²⁺ were abstracted considerably well by pyrite, and that the nature of these abstractions was due to the replacement of Fe
2+ on pyrite by these respective ions.
Since the activation is generally recognized as a process of alteration of the surface of minerals that permits them to respond to collectors, it appears desirable to examine xanthate abstraction and floatability of pyrite pretreated by the above-mentioned ions in order to confirm the mechanism of activation.
In the present paper, the amounts of ethyl xanthate abstracted by the pyrite which had been pretreated by these respective ions were determined at various pH values of the pulp. Further, the effects of activation by these ions on flotation were measured.
It was shown that the amounts of xanthate abstracted by pyrite were fairly increased only when the pyrite was pretreated by Hg²⁺, Ag⁺ and Cu²⁺, and that the floatability of pyrite was promoted by the presence of Hg²⁺, Ag⁺ and Cu²⁺ in the pulp.
It may be concluded from these results that the activation of pyrite by heavy-metallic ions is closely related to the abstraction of these ions by pyrite.

抄録全体を表示

Several metallurgical processes for the treatment of complex sulfide ores were discussed thermodynamically. Principles of selective leaching process were examined by a few types of equation, and the results are given and discussed in the pH-potential diagrams. The stabilities of metallic copper and various form of sulfates at roasting temperature are illustrated in the isothermal reaction diagrams in which partial pressures of basic components are taken for both axes. The selective sulfatization roasting in practice was explained successfully. After discussing the distributions of lead and zinc between matte and slag, the removal of zinc by volatilization was investigated stoichiometrically as well as thermodynamically. The possibility of removing zinc in metallic form during the course of copper smelting process was explained quantitatively, and it was confirmed that zinc sulfide could be oxidized into metallic zinc vapor in some extent, especially at high temperature.

抄録全体を表示

Iron blastfurnace slag or Pidgeon process' slag was employed as a ffllux in smelting of copper concentrates of a lab-scale.
Results obtained were as follows:
(1) Each slag was very effective as a flux in smelting of copper concentrates. Effective results were obtained with only 10 percent of these fluxes for the concentrates.
(2) Copper yield was 99.1-99. 4 percent in 5-min. smelting at 1, 300°C using 10°C 30% of these fluxes.
(3) increase of silica content in the charge impioved matte grade, though specific gravity of matte decreased and that of slag increased.

抄録全体を表示