It is well known that rocks are more or less deteriorated by sudden cooling after being heated. Furthermore, by repeating the cycle of heating-cooling, rocks might be expected to be weakened more severely.
In this paper, measuring the changes of the physical and mechanical properties of rocks including apparent specific gravity, P-wave velocity, Young's modulus and uniaxial compressive strength, the thermal fatigue process of rocks is characterized for four kinds of rocks, namely, OGINO tuff, EMOCHI welded tuff, AKIYOSHI marble and INADA granite. The cylindrical specimens are suddenly submerged into water after being heated and the cycle is automatically repeated in the testing machine.
The maximum temperature and the maximum cycles in the experiment are 600°C and 5⁴, respectively.
The main results obtained are as follows:
(1) The main failure mechanism is different between the crystalline rock and the sedimentary rock. The failure of the former takes place by the thermal interaction between minerals and that of the latter by the transient thermal stresses. As the result, crystalline rocks collapse to be particles or powders and sedimentary rocks are fractured initiating regular thermal cracks (Fig.6).
(2) The strengths of the rocks except welded tuff decrease remarkably within 5 cycles if the temperature is sufficiently high and the cooling time is larger enough (Fig.3).
(3) The strengths of the rocks except marble decrease as the cooling time increases. However, the additional effect is very small if the cooling time is larger than that needed for the specimens to be perfectly cooled (Fig.4).
(4) The cycles at which the specimens collapse exponentially increase as the temperature decreases (Fig.5).

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The effect of strain rate on the uniaxial and traxial compressive strength for Sanjome andesite is examined varying the strain rate from 0.85 to 850μ/sec. by a step of 10 fold change under the confining pressure up to 400kg/cm².
The preliminary uniaxial compression test shows that:
(1) the uniaxial compressive strength decreases with only small increase of moisture content in the test piece.
Therefore, a special care has been taken in preparing specimen for the following test programme. The test results are as follows:
(2) the increment of differential stress at the strength failure point is revealed to be about 75kg/cm² when the strain rate increased by a factor of 10;
(3) the square of the maximum principal stress at the strength failure point increases linearly with the confining pressure;
(4) the inelastic strain at the strength failure point increases linearly with the confining pressure. Though under a constant confining pressure, inelastic strain is almost constant regardless of strain rate.

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In order to obtain such technical data as are required for designing vertical double-belt conveyors, the authors carried out a stress-strain analysis of the double-belts through a non-linear finite element method. In the analysis the conveyor belt is assumed to behave as a membrane.
The main results are as follows;
1) The non-linear finite element model expresses the holding mechanism of the double-belts well.
2) When a particle is held between the belts just on an idler, local tensile stress which is 2 or 3 times larger than the mean value generates in the outer belt.
3) When the belt width is small, the condition that no local loosening should occur in the belts determines the minimum operational tension, while when the belt width is large, the equilibrium of the forces acting on the conveyed materiald etermines it.

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The size reduction of waste polymers has become an important subject in the field of waste reclamation.
Therefore the investigation carried out on the impact and compressive fracture energy of synthetic resins by using four kinds of unsaturated polyester resins whose rheological properties are different. The specific fracture surface energies were determined by means of flexural impact tests and compressive tests with different rates of loading.
It was found that the values of specific fracture surface energy were greatly influenced by the nature of resins and their viscous flow priperties and that the fracture energy was dependent on the load velocity.

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Brown and black-hair like or paste like-strange substances can be seen in the drainage and pools of underground workings.
The researches about these substances in the underground of three ceased mines were carried out by following methods.
Observation of underground state
Chemical analysis
Cultivation of bacteria
Electron probe micro-analyzer
The results are as follows,
1. Brown substance contains
(1) aerobic iron bacteria and aerobic sulphur bacteria.
(2) metalic-oxide, occasionally it contains up to 42% of iron.
2. Black substance contains
(1) anaerobic sulfate reducing bacteria mainly and aerobic iron bacteria and aerobic sulphur bacteria also.
(2) metalic-sulfide, occasionally it contains up to 15% of copper.
Through our researchs, it becomes possible to make these strange substances under artificially-made aerobic and anaerobic circumstances.
And by using these artificially-made strange objects, it is possible to improve the extraction technique of heavey metals in the mine drainage. This leads to the improvements of mine-pollution preventing technique, the reduction of its cost and the posibility of recovering the valuable metals from the drainage.

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In this paper, the classification and the concentration performances of the choking-free cyclone which is driven in a lower range of the screw speed was investigated.
The main results obtained are summarized as follows.
(1) The size of separated particles can be varied widely-20ηm to 4mm in this cyclone-simply by regulating the rotational speed of the screw.
(2) In these operating methods, the solid content in underflow showes the constant value which differs with each sample slurry. But the value of solid volume modulus for underflow (Ro) is equal to about 1.7 regardless of the slurry.
(3) The size of separation of the choking-free cyclone has been expressed experimentally by the equation (9). In case the solid content and the size distribution of the particles in feed and the amount of screw discharge are wellknown values, the size of separation can be obtained easily by the equation.
(4) The classification performance of the choking-free cyclone is closely related to the shaft torque of the screw conveyor. The speed control of the driving motor for the screw in relation to the torque makes it possible to operate this cyclone effectively.

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Toclarify the potential-dependence of the oxidation rate, 12 kinds of Pbconcentrates were oxidized in an acidic solution containing 3 mol/l NaCl, 13.3g/l PbCl₂, 3.8 g/l Fe, and pH l at 70°C. The potential (Pt vs. SCE) of the suspension was maintained constant at different potentials in the range from 0.25 to 0.45V by addition of KMnO₄ solution. The reaction follows the S°-forming oxidation with concurrent deposition of crystalline PbCl₂.
The results obtained reveal three aspects of the oxidation as follows.
(1) When the sample is repeatedly charged after the completion of oxidation of the first charge in a green solution, the oxidation rate of the second charge differes from that of the first charge. The difference is apparently due to (i) an appreciable waiting time only found in the first reaction, or (ii) the difference of the potential-dependence between the first and second reaction. For the reason of these differences it is considered that an oxidized species of S (may be thianate anion) formed in the first reaction affects the subsequent reaction.
(2) Nearly all of the reaction below 0.35V follow the quasi-first order kinetics. For concentrates with low Cu contents, the potential-dependence is represented by a pseudo-Tafelbehavior (see Fig.16),
E=E'+βlog (1/τ_0.50)
where E is the suspension potential and τ_0.5 is the half life time. The value of E' varies with the sample, while β is a constant at 0.12 V common to the samples. A few concentrates with high Cu contents show exceedingly high rates. The high rate is afttributed to a low value of β.
(3) When the potential is higher than 0.35V, the oxidation with the high rate follows a different kinetics which is independent of the suspension potential.

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A mathematical model for simultaneous leaching of various metals from a kind of are was proposed. In the model, the reaction rate equations of leaching are expressed as functions of the concentration of the species in liquid and solidphases, and the concepts of effective diffusion in the solid phase are introduced in order to estimate effects of diffusion of the reaction rate.
The theoretical results agreed with the experimental ones of leaching of nickel, copper, iron and other metals from manganese nodules with sulfuric acid.
The reaction orders with respect to the concentrations of nickel and copper in the solid phase are second-order, respectively, and that with respect to the concentration of iron is first-order.
The effective diffusion coefficient is independent of the particle size of the nodules.
The value of activation energy of the effective diffusion coefficient is so small (that is, about 2.5 kcal/mol) that the effective diffusion process may be considered to be molecular diffusion in pores of solid phase.
Also, the activation energies of the reaction rate constants with respect to nickel, copper and iron are 20.8, 12.8 and 20.8 kcal/mol, respectively.

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The direct reduction of ZnS by C and CaO and catalystic effect of Na₂CO₃, Na₂SO₄ and Fe₂O₃ were studied by the thermogravimetry and measurement of the generated CO and CO₂ in the temperature range 900-1100°C. The mechanism of the direct reduction was investigated by thermodynamic data and characterizing the residues at various conditions of the direct reduction by x-Ray diffraction and XMA.
The overall reaction of direct reduction is represented by the equation (1).
ZnS+CaO+C=ZnO+CaS+CO...(1)
It is conside-red that the equation (1) is divided into the following three elementary reactions and the equation (2) is the ratedetermining reaction of direct reduction.
ZnS+CaO=ZnO+CaS...(2)
ZnO+C=Zn+CO...(3)
ZnO+CO=Zn+CO₂...(4)
The small amount of addition of Na₂CO₃, Na₂SO₄ and Fe₂O₃ (about 1 wt%) to samples of direct reduction is very effective for activating the direct reduction due to accelerating the equation (2).

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In order to investigate the reducibility of Ouinne ore (from New Caleuonia) known as nickel oxide ore containing a significant amount of magnesia, reduction roasting and ammonia leaching have been conducted for the ore. Moreover, trials of improving the reducibility have been done by means of adding jarosite to the ore. Some of results obtained are as follows.
1) Leaching rates of Ni and Co in ammonia leaching were improved by heating reduction (simultaneous reduction with heating) as compared with preheat reduction (reduction after preparatory heating). When the ore was roasted by heating reduction in H₂ (50%)-H₂O mixed gas atmosphere at 973 K, leaching rates of Ni and Co were about 65% and 55% respectively.
2) When the ore was roasted with a small amount of ferric sulfate or potassium jarosite in the reducing atmosphere, thel eaching rate of Ni improved remarkably in the ammonia leaching. These additives seem to act as sulfidation agent on amorphous oxide temporarily and to prevent crystallization to forsterite of difficult reducibility.
3) When the ore was roasted with about 1O% potassium jarosite in H₂ (99.9%) atmosphere by heating reduction at temperature between 873 and 973 K for 40-50 minutes, leaching rates of Ni and Co were 85% and 65% or more respectively. These results are also interesting from the point of utilization of jarosite.

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