This investigation was undertaken to measure the Poisson's number and to draw the stress-strain diagram of “Asagai” sandstone which brought from the Joban Colliery.
The strain of the specimen was measured by electric strain gauges.
The strain of the specimen was measured by electric strain gauges.
The Poisson's number decreased from about 6.5 to about 4 as the tensile stress increased.
Next, in addition to drawing stress-strain diagrams for tension and bending tests, the diagram for the simple compression was introduced by a calculation and from the comparison between these diagrams, and it was found that the “secant modulus of longitudinal elasticity” for compression was about 1.4-1.5 times that for tension.

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On the drilling mechanism of rock with long rod, previously reported, it was proved that the drilling efficiency results not from the increase of rod length, but from the decrease of output of rock drill and the cuttings. Later results of the drilling tests with joint rod proved that the reflection energy at joint had an important effect upon the drilling efficiency. So we investigated on the reflection energy with various type of joints.
The results obtained are as follows:
(1) Even at the jointless rod (5m), energy loss was 10% per cycle of the elastic wave.
(2) The total energy loss of taper joint rod (5m) per cycle was 15%, buttress joint was 17 % and upset joint was 37%.(3) The reflection energy of taper joint was 4.0%, buttress joint was 3.0% and upset joint was 2.0%.(4) The friction loss of taper joint was 3.5%, buttress joint was 5.5% and upset joint was 16.5%.(5) The joint contactivity C_j was given by
C_j=H-H'/H
where H is impact energy, and H' is reflection energy loss.

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For the purpose of estimating the driving power of coal cutter required to coal seam cutting, we studied several foundamental experiments using coal cutter picks. In these experiments, the main and subordinate component of cutting resistance of coal were measured independently at the same time by the new type dynamometer with four strain gauges pasted. on an elastic steel circular disc, and the influences of depth of cut, characteristics of coal, rake and clearance angle, setting angle of pick and the neighbouring groove already cut by otherpick on the cutting resistance were made clear. By these results, estimation of the driving power of coal cutter became probable for the authors which will be explained in next report.

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In this study, the author considered thefloating velocity (or settling velocity) and the rising velocity of a irregularly shaped material in the vertical pipe by using the various coals.
From the results of this study, the following conclusions were obtained.
(1) The floating velocity vf was expressed theoretically as
υ_f=c_a·υ_fsc_ac₀=f (d_e/D)/c_f·4√ι/d_e
(2) In the case of the coal cD·f (de/D) was obtained as follows,
cD·(de/D) = (1-de/D)
(3) It was ascertained that the solid materials of ordinary irregularity in shape as coal had the floating velocity of about 0.6-0.8 times that of the sphere same volume.
(4) The rising velocity ye was exprssed theoretically as
υc=cω'(υω-υ_f).
(5) From the experiments cw' was expressed as
cω'=e^0.642 (υ_ω/υ^f-1)
with the error ± 5% in the various coals.
(6) From the theoretical consideration the velocity coefficient c_w' was obtained as
c_w'=K/√cD+2λζ'
where above each notation is as follows,
υ_fs=floating velocity of asphere of the same volume
c_a=calibration coefficient
c_f=coefficient of the floating velocity of a sphere
l=maximum length of the material
d_e=equivalent diameter of the material
D=diameter of the pipe
cD·f (d_e/D) =the coefficient and the function determined from the experiments
υ_ω=velocity of water
c_ω'=veloCity coefficient
K, ζ'=constants determined from the sige and the shape of coal.
(7) The more the increase of the velocity of water υ_ω the less the drag coefficient cD and the apparent frictional coefficient λ, therefore the coefficient of the velocity c_ω' was not constant and increased.
This was the reason that the c_ω' was expressed as the above experimental equation.

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The writer investigated thoroughly the relation between wettability and floatability of mineral particles in flotation process.
Pyrrhotite particles acted by various pH xanthate solution, were used as specimen. And the measurement of wettability and floatability was carried out in a similar condition each other.
The following two aspects were made clear:
(1) Wettability of mineral particles relates directly to floatability, and their empirical curves show a symmetry each other.
(2) Floatability (flotation recovery) shows 100% at the point where contact angles are equal to or more than 90°.

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In attacking the problem, the author has measured the flow velocity distributions end pressure distributions in the cyclone by using a direction-finding pitot tube with a single hole under the various operating conditions.
Then it was understood that the diameter of vortex finder and dimension of inlet nozzle are the important factors.
From the above experimental results, it could be explained that the flow in the cyclone would be of Rankine's vortex consisting of a free vortex combined with a sink.
In additions, the traces left by spiral flow of liquid on the conical wall were examined and the three-dimentional spiral curve thus obtained was developed in one plane. From the results, it is apparent that the main stream of helical flow is of equiangular spiral.

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During the pre-war days, a few cyanide gold mills had been gaining good results by substituting partly Aero Brand Cyanide made in America for NaCN. After the World War II, the domestic production of Ca (CN) ₂ was commenced by carbide industries. The writers attempted to apply it to the cyanidation plant, and its foundamental research for six months proved to be satisfactory. Consequently, since August 1956, the over-all use of Ca (CN) ₂ for the operation, resulted in our great profit by ecconomy of the reagent cost as well as the promotion in disolution of silver.
The writers compared H₂SO₄ method with ZnSO₄ method in the fundamental study to remove and recover various cyanide salts, which are unfavourable to the cyanidation of gold ore. It is found that the latter method has more advantage industrially.
As further applications of Ca (CN) ₂ to the non-ferrous metallurgy, by using it as dissolving reagent, the behaviour of various elements has been made clear in the experiments of metallic dross or flue dust, for which any appropriate metallurgical method has not been discovered at the smelters.

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