The “Mine Police Regulation” was initiated in 1892. The mining industry developed rapidly since the beginning of the 20th century in Japan. But as the natural conditions in mines are unfavourable, the number of accidents had increased especially during and after the World War II. Therefore the “Mine Safety Law” as well as the “Mine Safety Regulation” were enacted in 1949 to ensure mine safety.
In past 25 years up to 1974, the results of mine safety have been improved year by year. But we have many difficult problems in future as follows;
(1) Difficult technical problems in deep mines (Underground temp. Rock bursts, Outburst of gas. Spontaneous combustion)
(2) Reduction of working time (Increasing of holidays, Abolition of midnight working)
(3) Damage by mining and environment
(4) Deficiency of young workers (Increasing of old workers)
(5) Analysis of mine accidents
(6) Education and training of young engineers
(7) Working circumstances

抄録全体を表示

The Oka, carbonatite complex is located 32km west of Montreal, Quebec, Canada, and is situated west end of “Monteregian Hills alkaline rock petrographic province”.
The St. Lawrence Columbium and Metals Corporation Mine is situated near the center of the Oka carbonatite complex. The main ore mineral is pyrochlore, and the annual production is about 2250 tons of pyrochore concentration containing about 52% Nb₂O₅.
Many of polyphase inclusions having very small size are found in calcite, apatite and biotite from the Oka carbonatite.
The filling temperatures of fluid inclusions in calcite and apatite from carbonatite were determined under heating stage. From these results, the range of the filling temperatures of calcite is from 395°C to 275°C. 320°C in average, the range of apatite, from 350°C to 260°C, 300°C in average.
The solid phases in polyphase inclusions in calcite and apatite show an interference color between crossed nicols, however, it does not melt at upper temperature than filling temperature of fluid inclusions. Mineral species of solid phase are not yet been determined.
The analyses of experimental data allow to assume that the range of formation temperature of the Oka carbonatite is considered from 800v to 600°C.

抄録全体を表示

In succession to the previous study, stiff loading tests were made by using Dilatometer on some rocks such as sandstone and marble in the present study. Especially, the cyclic loading tests were systematically performed, that is, the load on rock sample at the deformation stage was reduced to zero level and again increased. By this experimental procedure, the permanent strain was separated from the total strain.
The main results are as follows;
1) Young's modulus, which is obtained from the mean slope of the unloading and reloading curve, is almost kept constant values in the post-failure region of uniaxial compression.
2) The ratio of the permanent strain to the total strain increases with the total strain. And the relationship between the permanent strain and the total strain is approximately expressed by Weibull's distribution function. That is,
εp {1-(-exp (ε/ε_cs)^m/a}
where
ε=ε_e+ε_p,
ε_cs=critical strain at failure stress,
m, α are parameters.
3) The volumetric strain of rock after failure is irreversible even by unloading.
4) The magnitude of the volumetric strain in dilatation is expressed in simplified form as
ε_νp=cεp
where c is coefficient.

抄録全体を表示

This paper deals with a basic research on the wet separation method using the combination of sink-float separation and flotation. This method is characterized by classifying waste plastics into several groups for their easy reuse.
Experiments were performed on a mixture of plastics in the presence of foreign matters, such as paper, wood, glass, aluminum foil. In the sink-float separation of waste plastics, one of the most important factors which govern the separation was found to make the surface of the plastics and the likes hydrophillic. Accordingly, in the present study, the kind and concentration of surface active agents to be used were determined after examining the wettability of surface of plastics. In flotation, it was necessary to float only plastics from the sink-float separation products which are lighter than water, such as paper, wood, polyethylene, polypropylene, and etc., and to separate polyethylene from polypropylene. The size of thermoplastic resin fragments to be floated was of the order of 10-20mm square. For these purposes, a new type of airlift flotator was devised to examine the effect of surface active agents on the flotation behavior of plastics.
The accuracy of separation of plastics was 98.3 to 100% in the sink-float separation and more than 95% in the flotation test, respectively.

抄録全体を表示

The effects of impurities on the morphology of zinc electro-deposition from acidic zinc sulfate solution (Zn²⁺60g/l, H₂SO₄150g/l) were observed with a scanning electron microscope and an optical microscope. The results were summarized as follows:
1) Zinc deposits from the pure electrolyte appear as a mixture of hexagonal crystals which have grown with various orientations.
2) The presence of impurities affects the surface structures of zinc deposits. From the effects on the above-mentioned structures, impurities are considered to be classified into following four types:
(a) lst groups: In, Cu, Co. Addition of 10mg/l In, Cu and Co to this electrolyte do not have influence on the zinc deposition. Namely, in these cases, microstructures are almost the same as that of pure zinc deposit.
(b) 2nd group: Ni, As, Cd, Pb. With the addition of 10mg/l Ni, As, Cd and Pb, the crystal growth of zinc has been suppressed and fine crystallites are obtained.
(c) 3rd group: Hg, Ag, Ga. The presence of 10mg/l Hg, Ag and Ga gave a striped zinc deposit of bright crystals.
(d) 4th group: Ge, Sb, Te, Sn, Tl.
Additions of these impurities affect remarkably the structure of zinc deposits and in each case, zinc crystals have characteristic types respectively.

抄録全体を表示