There are many places along the Japanese National Railway line where landslides and rock falls have frequently occurred. And geologically a half of such places is in the crystalline schists regions, and Central Sikoku is the typical one. In order to collect some basic informations on preventing such disasters in crystalline schists regions, we measured some physical properties of those typical rock samples which were collected from Central Sikoku. They were 31 types of paleozoic crystalline schist and we cored 892 cylindrical test pieces from them with a diamond drill, and we measured their values of specific gravity, coefficient of water absorption, compressive strength, tensile strength, shear strength, elastic wave velocity, Shore's hardness, Schmidt's hammer test hardness, Young's modulus and Poisson's ratio, respectively.
As the results of our measurements, we found that the cleavage plane of crystalline schists, as well as their schistosity plane and foliation, greatly affects their physical properties as shown below;

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In order to carry out the underground gasification of coal, we must at first examine the relations, between movement velocity of borehole fire front and blast quantity, oxygen concentration in the blast.
According to the many observations in USSR, the increase of the concentration of oxygen in the blast and the blast guantity increase the rate of fire front movement.
The author analyzed these relations mathematically and calculated the necessary dimensions, i.e. suitable concentration of oxygen in the blast and necessary quantity of blast in case of underground gasification of coal in Japan.
And also relations between humidity of coal seam and max. temperature of borehole were examined. By these results, we will plan the most desirable underground gasification layout in Japan.

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For the hydraulic transportation of solid material the authors tried to develop the pressure drop in inclined pipe and as the results of theoretical and experimental studies the following conclusions were obtained.
(1) The increase of pressure drop Δp_s due to the solid material was expressed as follows,
ΔP_s=λ_s ΔL/D γwυ²m/2g
Where the coefficient λ_s was expressed in the case of constant velocity and concentration of mixtures
λ_s=η₀Ψ=η₀· (d_s/D)^-1(1-ζ)²/ζ
ζ=υ_{s/υm=1-1/Fγ √ 4(ρ -1) /3CD0(ds/D) (μscosθ +ρsinθ ρ-1)}
(2) The hydraulic gradient i along the pipe was expressed as follows,
i=i_w (1+φ·k)
where the coefficient of pressure drop φ was expressed as follows by the exprience using the sand (ρ=2.75, d_s=0.4mm)
φ=φ₀F_γ^-n=(100-23.6θ) F_γ-(^{4.4-2.1θ0.342})
Nonmenclature
d_s, D=equivalent diameter of solid and inner diameter of pipe (m)
υ_s, υ_m=mean velocity of solid and mixtures (m/s)
i_w=hydraulic gradient with water alone (mAq/m)
F_r=Froud's Number=v_m/g.D
ρ=specific gravity of solid
θ= inclination of pipe (rad.)
μ_s, C_D0=frictional coefficient for pipe and drag coefficient of solid
k=rate of mixture
η₀, φ₀, n=constants

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Mechanisms of the separation of feldspar from quartz by flotation, using cationic collectors (long chain amine) in acid circuit with hydrofluoric acid have been discussed.
In the acid solution, the adsorption amount of dodecyl ammonium acetate (DAA) on feldspar which had previously been treated with hydrofluoric acid was larger than that on the untreated one or on quartz. The variation in zeta-potential obtained for the acid-treated and untreated feldspar showed so small differences in shapes and in characteristics that little effect of the electrostatic adsorption could be expected to explain the difference in adsorption amount between the acid-treated and untreated feldspar.
Considering the action of feldspar with hydrofluoric. acid and the results of observation by infra-red spectroscope and X-ray diffraction, it was assumed that sodium or potassium fluosilicate was formed on the surface of the mineral and it reacted with amine to give a hydrophobic character to the mineral. Adsorption of DAA to sodium or potassium fluosilicate was so strong that the adsorbed products could not be removed from the surface by washing.
Conceivable conclusions drawn from the studies were that hydrofluoric acid acted as activation agents for feldspar and the acid reacted with quartz and feldspar to form fluosilicic acid. Then the acid was led to potassium or sodium salt by the reaction between the acid and potassium or sodium ion. Amines reacted with insoluble fluosilicate on the surface and made feldspar floatable.

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The effects of roasting temperature, CO concentration and Pco2/Pco ratio of the roasting gas mixtures on the decomposition rate of, zinc ferrite and the extractability of zinc in reduced products with 0.1N H2SO4 solution were investigated. Decomposition of zinc ferrite are considerablly easy even with reducing gas mixtures of low CO concentration. The reducing decomposition reaction of zinc ferrite proceeds as folows;
3ZnFe2O₄+CO=3ZnO+CO₂ (1)
or (2+x) ZnFe₂O₄+xCC=3xZnO+2Zn_1-xFe+_xO₄+_xCO₂ (1a)
Fe₃O₄+CO=3FeO+CO₂ (2)
The effect of roasting temperature on the rate of the reaction (1) is very small (the apparent energy of activation is 1.7 kcal/mol), but finally attained fraction of the decomposition is dependent on roasting, temperature.
The rate of the reaction (1) is neady proportional to Pco, when Pco₂/Pco ratio of the reducing gas: is 1.3.
Value of Pco₂/Pco ratio has an effect on the finally attained fraction of the decomposition, i.e. the smaller the value, the larger the ratio becomes.
On the way of the reaction (1), FeO was formed in spite of no potential for reducing gases to reduce. Fe₃O₄ to FeO, and an unknown phase (probably tetragonal crystal) was appeared at, the same time. The. unknown material is considered as the origin of FeO phase, that is, ZnO and FeO may separate from Zn_1-x. Fe₂+xO₄ in a form of the unknown material, thereafter perhaps the material decomposes into ZnO and FeO.
Zinc is easily extracted at high percentages by 0.1N H₂SO₄ solution from the reduced products of zinc ferrite. Leach solutions contain more Fe²⁺ ion than the expected value from the stoichiometric Fe²⁺/Fe⁺-ratio of Fe₃O₄. The above-mentioned FeO formation was presumed from this fact.

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The authors investigated on the smelting of lead sulfide are by so-called “soda process”. The main results obtained are as follows.
(1) When lead sulfide are was heated with soda ash, pyrite cinder and coke at about 900°C, lead sulfide was reduced to lead and sulfur reacted with sodium carbonate, ferric oxide and carbon to form so-called “soda matte”. The over-all reactions are probably as follows.
PbS+Na₂CO₃+2C=Pb+Na₂S+3CO
2PbS+Fe₂O₃+3C=2Pb+2FeS+3CO
In this case, the reactions proceeded completely and most suitably, when the ratio of Na₂S to FeS obtained by above reactions was 54/46 by weight.
(2) For most suitable quantities of reducing agents, 1.2 equivalents to PbS in the are were required.
(3) The recovery of metallic lead increased with temperature. For instance, the yield was 97 percent at 1000°C.
(4) The purity of lead bullion was higher tha-n those obtained by the other processes.
(5) The results obtained from erosion tests for the refractories used for this process showed that Corhart Black and high chrome steel were more resistant against erosion than other refractories.

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