Stress condition in a medium caused by blasting with two free faces are very complicated ones, but these are analyzed by applying the measured values concerning the stress waves to equations derived from the theory of elasticity by using an electronic computer. In this study, the stress conditions produced in a brittle sandstone caused by an explosion were analyzed for two free face blasting of which geometrical conditions were as follows corner angle between two free faces was 90° and a charge was placed on the line which divided the corner angle equally. One of the most interesting results obtained in this stress analysis was that the development of corner fracture which was anticipated on the basis of stress reinforcement due to the superposition of the reflected waves from each free face could not be expected for the case of brittle rock, while it was observed experimentally for some kinds of metals and plastics.
On the other hand, the results of the experimental studies which were carried out to make sure the results of this stress analysis also showed no trace of corner fracture development. Therefore, it was clarified both theoretically and experimentally that the corner fracture development in brittle rock could not be expected.

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The authors have made efforts to clear out the phenomena occurring when a shaft well is sunk by air blowing. As a first step, they investigated, previously, the variation in stress in a shaft well being sunk, as well as the earth pressure acting on the well. The present paper describes the results of further investigations made at the Shaft 3 of the Ariake coal mine.
It has been found that air blowing itself decreases the frictional resistance between the ground and the outer surface of a well by no more than about 0.3t/m², and a deep sinking of a well, if it happens, decreases the resistance further by 0.8t/m², that the maximum accelaration and velocity are proportional, within a certain limit, to the displacement of a well occurred by each air blowing, the maximum values being 1.47m/s² and 2.34m/s respectively, that a well begins to sink when the bearing resistance of ground at the shoe of a well becomes less than 1000 t and a well ceases sinking when the resistance increases to reach from 2000 to 4000 t, and that any water hammer phenomena cannot be observed inside a well during sinking.

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In this paper, to contribute to the development and practice of the electromagnetic inspection of a wire rope, we introduce our method and state the result of some fundamental experiments.
Next, the result of field inspections of a Cable Belt Conveyor which were carriedout with trial equipment and the procedure of estimation of the present strength of a wire rope by the electromagnetic inspection record are stated.

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When magnetite, hematite and quartz are ground by a ball mill, their grinding products follow the Gaudin-Schuhmann size distribution formula y=100 (x/k) ^a, where y is the cumulative weight percent [%] finer than size x[μ], k is the size modulus [μ] and α is the distribution modulus [-]. The grinding products which follow the G-S size distribution formula were rolled into green balls, and the capillary pressure in the balls is expressed by the following equation;
Zα=A (0.45 cos θ)(F_(α)/k){(1-ε)/ε}.(a) where Zα[g/cm²] is the capillary pressure determined, θ is the contact angle [deg], ε is the porosity [-], k/F_(α) [cm] is the average size of the grinding Products following the G-S equation, And A corresponds to the ratio of the rise of the liquid in the actual capillaries to that in idealized ones with circular cross sections of a uniform diameter.
From the measurement of the crushing strength of the green balls, it is found that the maximum crushing strength T [g/cm²] is proportional to the capillary pressure Z [g/cm²] which is calculated on the assumption that A=1 and cos θ=1 in the equation (α).
Assuming that T=Z_a, T/Z equals to A. The value of A is 1.3 for magnetite and quavtz, and 0.6 for hematite, respertively.
The capillary pressure in the balls rolled by the sized particles is expressed by the following equation; Z_α=A (0.45 cosθ)(1/χ_αv){(1-ε)/ε}(b) where χ_αv is the average size.
Using the value of Z_α obtained by the measurement of capillary rise or the maximum crushing strength of balls, A is estimated to be 1.3-1.5 for magnetite, hematite and quartz from the equation (b).
From the above results, it is noticeable that the value of A is considerably less than 1 of hematite.
Probably, the behavior of finer Particles, in respect of ther Plugging in the voids of coarser particles, will be particular in the grinding products of hematite

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To determine the applicability of metallic materials for equipment which would be exposed only to zinc vapor, the corrosion resistance of pure iron and carbon steels to zinc vapor was investigated in 150-hr. exposure in the temperature range from 900° to 1000°C. The concentration gradients of zinc in the diffused layer after experiments were analysed by an electron probe micro-analyser, and then the diffusion coefficients and activation energies were calculated.
The diffusion coefficients of zinc vapor in the Fe-Zn system, increased with the increase of the zinc content, were obtained at the order of 10^-10cm²/sec in the temperature range from 900° to 1000°C, and decreased largely by adding 0.25%C or more into pure iron. The activation energy of diffusion in pure iron was about 5400cal/mol.
From the abrupt change in diffusion penetration curve, it was suggested that the limits of the γ loop.(γ change to α) in the Fe-Zn system was smaller than that indicated in the Fe-Zn diagram by H. H. Stadelrriaier and R. K. Bridgers.
Also, the activity of zinc in the Fe-Zn system was calculated from the surface concentration and the temperature of sample and zinc bath. It was observed that the activity of zinc deviated in a positive direction from ideality and the degree of the deviation decreased with temperature decreasing.

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The complex sulphide concentrate containing 10.1 pct of Cu, 19.8 pct of Zn, 19.0 pct of Fe and 31.8 pct of S was treated with aqueous ammonia solutions at elevated temperature under pressure with oxygen. Extractions of Cu, Zn and S were influenced by temperature, oxygen partial pressure, pulp density, agitation of pulp and initial free ammonia to copper and zinc molar ratio.
The results obtained were as follows;
1.Extraction of copper was over 90 pct at 80°C, and extraction of zinc was over 90 pct at 115°C. Thus a leaching temperature of 115°C was recommended as the optimum.
2.Variation in oxygen partial pressure had a little effect on the extractions of copper and zinc. By reducing the temperature, the effect of oxygen partial pressure increased.
3.Extractions of copper and zinc were unaffected by varying the pulp density from 10 to 26 pct.
4.Though pH ranges of stability of Cu (NH₃) ₄⁺⁺ and Zn (NH₃) ₄⁺⁺ were extended with increasing ammonium sulphate concentration, the leaching rates decreased.
5.The leaching rates and extractions were unaffected by varying the NH₃/(Cu+Zn) molar ratio over the range of 6 to 7.
The optimum conditions to be attained in experiment were as follows; temperature 115°C, pulp density 20 to 25 pct, NH₃/(Cu+Zn) molar ratio 6 to 7, leaching time 7 hrs.
Under the above mentioned conditions, 95 pct of copper, 90 pct of zinc and 67 pct of sulphur were extracted.

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