Steel arch sets have been widely used in coal and metal mines for roadway support. However, some of them were recently replaced by rock bolts especially in U.S. coal mines and tunnels with large cross-section. Through the current developments of theory and practice, the rock bolt support can be considered as a compatible alternative for the arch support. Included in this second report are the results of in-situ measurements at the arch supported roadway comparing with those at the bolt supported.
Up to this date (200 days after installation), convergence and radial extension of rock wall at the arch supported roadway are considerably larger than those of the bolt supported roughly by the factor of 1.5 to 2. A temporary conclusion may be that the rock bolting is superior to the arch set. Especially in the very early stage, say, within a few days after installation, rock bolting is favored for its immediate effect, while the effect of arch set is delayed until firm contact of arch set or timber lagging with rock wall is established.
Similar to the case of rock bolt support mentioned in the first report, the convergence and radial extension at arch supported roadway follow the semi-log relationship, linear increase with log time. Interestingly enough, the specimen obtained at the test-site follows the logarithmic creep law. This is remained for future research to combine the semi-log relationships observed at in-situ and laboratory tests.

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Experimetal studies on destruction of cement mortar induced by internal high pressure gas were carried out. In this lst Report, flaking type destruction of mortar are shown photographically, and its charactericities are discussed. The results obtained from them are as follows:
1) Under an experimental condition, that is S_t=1.0 (kg/cm²) and P_r=285 (%), when one end surface of confined mortar in which high pressure gas (5-6kg/cm²) has been existed is suddenly exposed to the atmospheric space, the mortar is usually flaked into pieces from surface to bottom. And the demolished cavity that was formed in the vessel was very similar to those of conical outbursts.
2) It is confirmed that the most necessary condition for the occurrence of mortar outbreaking is the creation of steep gas pressure gradient within the narrow neibourhood from the surface of material.
3) A lot of cracks that are nearly pararell to the surface are possible to be created by tensile stress that will be distributed corresponding to the gas pressure distribution.
4) If the internal gas pressure is set up higher, the depth and the volume of the demolished cavity becomes deeper and larger.

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In a pipeline transport of coarse solid particles, it is important to analyse the mechanism of slurry flow with the stationary bed in a pipe. The object of this paper is to present the condition of incipient motion of solid particles resting on the stationary bed in a horizontal pipe. The first step of this analysis was the assessment of the effect of cross-sectional shape above the bed on flow resistance. The next one was the study on the applicability of the Shieldsdiagram obtained in open channel flow to closed conduit flow. Based on these studies, an analytical work was developed to derive the relationships of average flow velocity, volumetric flow rate and hydraulic gradient of free flow area above the stationary bed against the thickness of bed.
The result of the presented analysis may be summarized as follows:
1) the head loss due to water, which is necessary for the calculation of the slurry flow with the stationary bed, could be reasonably determined; and
2) the experimental relationship deduced by Gibert and Condolios et al.
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was valid for practical purposes as long as the level of deposition do not exceed the pipe radius.

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A series of there studies is concerned with operation of an are dressing plant with a closed circuit for water from a standpoint of reducing consumption of water and preservation of an environment from pollution by the waste water. The authors constructed the kaoline are processing pilot plant of closed circuit and experimented on the plant operation to be recycling the waste water. The previous paper reported the results of continuous water recycling operation which was conducted for long period at about 50 and 90% recycling ratio of the waste water. The mineral balanceand quality of concentrate was obtained from the results of the operation tests. This paper present the results on the investigation and discussion about the changes on standing of the accumulated materials in the closed system and the these effects on the process performance. The soluble materials which were accumulated in the system were little and the effect for the processes was fractionally in 50% recycling ratio. However, in the case of 90% ratio, the amount of soluble materials increased with a passage of time. The concentration of Fe³⁺ ion in recycling water reached nearly 7000 ppm, Na⁺ ion was 11000 ppm, TOC was 1300 ppm at the finish time of the experiment. It reduced gradually the separating performance by these accumulations. These soluble materials affected remarkably the processes of settling pond, flotator, bleaching and so on, and the quality of the concentrate. It became clear from the above mentioned that the closed systematization enabled to circulate within a certain acceptable value for the recycling ratio of the waste water.

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Effects of the atmosphere of preparative procedures preceding flotation on the floatability of pyrite were investigated. Pyrites from Yanahara and Toyoha mines were used as the samples. The investigations laid emphasis on a comparison of effects of dry and wet grinding-screening procedures on the floatability of pyrites.
The main results obtained are summarized as follows:
1) Floatability of the pyrite sample from Yanahara mine is much larger than that from Toyoha mine.
2) The order of the floatability of pyrite flotation which applied three kinds of preparative procedures (A, B and C) was C>B>A.
where
A: dry grinding and dry screening
B: dry grinding and wet screening
C: wet grinding and wet screening
3) There is a negative correlation between the floatability of pyrite and the amounts of iron and sulfate ions dissolved from the mineral during flotation.
4) A remarkable difference in the zeta-potential of pyrite is recognized between the preparative dry grinding and wet grinding. However, it is difficult to explain the flotation results with the zeta-potential data.
5) No relations are recognized among the oxidation-reduction potential of flotation pulp, the amount of free sulfur formed on pyrite surface, the difference of the pyrite samples, and the kind of the preparative procedures.

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Various commercial copper anodes were heat treated by an annealing/slow cooling process, and their dissolution characteristics were extensively examined using copper electrorefining electrolytes.
The results obtained indicate that the following major beneficial effects could beachieved through this heat treatment;
1) The dissolution activity dramatically increases, which is responsible for the combined effect of anode slime layer becoming significantly more porous, thus making the diffusion of Cu²⁺ ions much easier, and also of the, anode itself being rendered very active.
2) As its consequence, cell voltages of the so heat treated anodes become significantly lower than those obtained for the untreated.
3) Slime fall dramatically decreases by 24 to 43% for all the anode samples tested, and
4) The colloidal (or amorphous) nature of anode slimes is considerably reduced, which results it a reduced incidence of the suspended slime particles to be formed in copper electrolyte, which, in turn, reduces a risk of the copper anodes to be contaminated with such impurities as As, Sb, Bi, Se etc.
It has also been shown that the distribution of slime-forming compounds dramatically changes as a result of this heat treatment.

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The relationship between distribution coefficients and oxygen partial pressure have been reported in the previous paper. In this report, the influences of temperature and the compositions of slag and metal on the distribution of minor elements between calcium ferrite slags and metallic copper are described.
From the standpoint of the molecular model for slags, it was made experimentally certain that the Henry's law is valid when the molecules of CuO_0.5, AgO_0.5, AsO_1.5, SbO_1.5 and BiO_1.5 in slags are postulated.

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