Model tests reported previously have shown a complicate behaviour of concrete plug and failure process of weak rock around the plug.They remain some technical problems which could not be revealed in the model test.
Thus, the in situ test is designed and conducted to reveal the problems remained, particularly the effect of fracture crack growth on the permeability of rock mass around the concrete plug.
The failure process is analysed by means of elasto-plastic F.E.M. analysis, and the predicted mechanical behaviour of plug as well as surrounding rock are compared with the test result.
It is indicated that the tension crack is generated in the rock mass near the corner of back face of concrete plug under a hydrostatic pressure of several kg/cm². This tension crack does not induce immediately total failure of rock mass, but remarkably increases the permeability of it.
Finally, a modified design of concrete plug has been suggested to prevent the occurence of tension crack and to keep watertight concrete plug.

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When a mine roadway is driven in discontinuous rocks, it may be expected that the stability of the roadway will be diffrent from that driven in continuous rocks.
The effects of horizontal discontinuities on deformation and failure of a roadway were studied with both the Finite Element analyses using the joint element and scale model tests using a sand-plaster mixture as a model rock.
The results from the FEM analyses and model tests showed that the state of deformation and failure of a roadway driven in discontinuous rocks is much affected by the behaviour of the discontinuities which depends on the properties of the rocks themselves, the primitive stresses (applied pressures) and the properties of the discontinuities.

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In the Toyoha mine the ground temperature is very high owing to hot mineral water found in the ground. Several veins bearing zinc and lead ores have been mined down to the depth of 300m from the level of the main entry. Since 1974, the 450m level of Tajima vein has been developed by driving a drift, where the rock emperature is from 80 to 90°C.
To obtain fundamental data for designing economical cooling, the heat balance in the drift was investigated by several measurements in August of 1974 and 1976, and continuously from August 1978 to July 1979. From these investigations the following informations were obtained.
The heat transfer through rock affected by hot mineral water to an air current is, against our expectation, not great, and is at most twice as much as a theoretical heat transfer through rock unaffected by hot mineral water. However in the case that an air current is in contact with hot water which flowed or seeped into the drift, a great heat transfer to the air current, sometimes ten times the theoretical heat transfer from rock unaffected by hot mineral water, will take place.
For effective cooling it is advisable to prevent inflow or seepage of hot mineral water, to prevent the air current from direct contact with hot water. and to use chilled water efficiently.

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In this report, by the measurement of contact angles of formed powder-liquid systems between coal (or model materials of coal) and water, the author has made clear the relation between wettability of coal and coal elementary composition.
He has been submitted the following regression formula by the data of Table 4.θ=0.96 [H]-1.51 [O]-2.60Ash+15.71 (γ=0.916) here [H] and [O]: atomic ratios H and O per 100 atom C respectivelyθ: contact angle between coal and water
By the above-formula, the information of Figs. 1-6 on the bituminous coals (their elementary composition has shown in Figs. 7-9), brown coals data (Figs. 10-12 and Table 7) and the analysis on model materials of Table 8, the following points have been confirmed in this work.
Firstly, the wettability of coal is regulated by ash. On the relation between coal organic elementary composition and the wettability of coal, the superiority of atom ratio [0], especially oxygen functional group is hydrophilic tendency, the other way, that of aliphatic hydrocarbon and aromatic polymerization in the case of bituminous coals are hydrophobic.

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The effects of floc porosity change under turbulent motion during the process of their formation are examined using numerical solutions of Population Balance equation.
According to the results of numerical experiments,
1) When flocs have higher porosity, larger flocs form in shorter time during coagulation process. The size distribution curve of flocs is seen apparently different from that of Droplet Model.
2) When floc porosity is constant or continuously changes under coagulation process. the size distribution curves of flocs can be represented by straight line in Rosin-Rammler Diagram. And the gradient of the line becomes smaller in the course of coagulation. This phenomena is one of the peculiarities of Turbulent coagulation. The gradient of the line does not change in the course of coagulation.
3) If floc porosity is changeable during coagulation, the self-preserving spectra can be obtained only when one uses the new similarity variables based on the weight of floc consituents.

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A proposed mechanism leading to precipitation of a CuSO₄salt on the surface of a passivating copper anode was discussed.
A special technique has been developed to facilitate extracting an electrolyte sample from inside the anode diffusion layer at any given time of anodization, and it has been shown that an electrolyte extracted near the onset of passivity typically contains (g/l) 96 Cu, 18 Ni and 113 H₂SO₄. The concentration of H₂SO₄assayed here is represented, in the greater part, by HSO₄^-.
In such a highly concentrated electrolyte in terms of Cu²⁺and HSO₄^-ions, the stability of hydrated Cu (H₂O) ₄²⁺ions near the surface of a passivating anode may gradually decrease, and in its place the following sequential substitution reactions become more predominant;
Cu (H₂O) ₄²⁺+HSO₄^-→Cu (H₂O) ₃ (HSO₄^-) ⁺+H₂O (1)
Cu (H₂O) ₃ (HSO₄^-) ⁺+HSO₄^-→Cu (H₂O) ₂ (HSO₄^-) ₂^°+H₂O (2)
and so on.
The productant in equation (2) is presumed to be a weakly associated ionic pair, which autodecomposes when its concentration exceeds a certain critical point, like
Cu (H₂0) ₂²⁺…(HSO₄) ₂²⁺→CuSO₄+H₂SO₄+2H₂O (3)
to produce CuSO₄ (s), H₂SO₄and some water. Thewater molecules discharged through this process seem to play a key role in redissolving the precipitated CuSO₄salt while Cu²⁺and HSO₄^-ions are newly supplied to this site of reaction to be ready for the subsequent process (2) to reoccur. Thus a certain cyclic relation is predicted to build up between the processes (2) and (3) at a near-saturation state of the electrolyte near the passivating anode.
Electrolyte properties at a saturated state were also thoroughly reviewed to support the possibility of this proposed model.

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The equilibrium distribution coefficients of lead between the matte, slag and metallic phases in the silica-saturated copper smelting system were determined. The conditions investigated in this study ranged from iron and copper alloy saturation at low oxygen potentials to a sulfur dioxide partial pressure of 0.1 atmosphere. The lead was found primarily in matte except in the presence of the copper alloy phase. The accumulation of lead in the copper alloy phase was pronounced, particularly at low oxygen potentials. Under conventional smelting conditions. the lead content in slag increased with inoreacing matte grade. The behaviour of lead was explained by proposing metallic and sulfidic species in matte and oxidic and sulfidic dissolution in slag. In this manner, the activity coefficients of the various species were calculated in the respective phases.

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