The turbulent characteristics in flotation machines were recently measured and the turbulent fields were confirmed to be isotropic except the impeller zone. Thus the isotropic turbulent theory was applied to determine the local distribution of the turbulent time and space scales and to analyze the energy propagation. It was also confirmed that mineral particles damped and air bubbles enhanced the turbulent motion in flotation machines.
The turbulent motion of particles must be one of the most important factors that decide the micro-processes of the flotation proce SS. Hitherto the equation of the tumbulent motion of pamticles has been analytically or numemically solved only for a mono-dispersed system. The results revealed that particles in flotation machines were able to be considered to move approximately with the fluid surrounding them under conventional flotation conditions.
The collision process between mineral particles and air bubbles must be elucidated in order to build a micro-process model for a flotation process. This problem has been tried to solve using similar methods as for coagulation problems and a few studies were reviewed.
The micro-processes in classification and thickening processes have been studied with equations of diffusion and the diffusion coefficients have been given by spatially average values. However a study that the turbulent characteristics were measured in a hydrocyclone showed that the turbulent diffusion coefficient was spatially distributed.
The study of the micro-processes in mineral processing is now progressing and there are many problems to be solved.

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To store the large amount of liquefied natural gas (LNG), new methods of storing LNG in unlined rock caverns have been discussed in many countries. Thus, a systematic study has been undertaken to investigate the effects of crvoeenic environments on the structure of rock cavern. In this study, mechanical properties of Emochi andesite and Sori granite, in both oven-dry and water saturated conditions, were investigated at temperatures from +20° to-180°. The following results were obtained.
1) Compressive and tensile strengths of dry specimens increased slightly with decreasing temperature, while those of saturated specimens increased rapidly.
2) Secant Young's modulus for saturated rocks tended to increase gradually down to-130°C and kept almost constant following further lowering of temperature. But that of dry rocks was not changed by temperature decrease.
3) Poisson's ratio of dry specimens did not vary much with the change of temperature, while that of saturated specimens was influenced by temperature.
4) It is estimated that dependence of these mechanical properties of rocks on temperature relates to the freezing phenomena of pore water.
5) Coefficient of thermal expansion and temperature range for expansion coefficient were given in Table 1.

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It is one approach to estimate slope stability to know the stress and deformation in the region of the slope. The factors affecting slope stability could be as follows: mechanical property of rock, angle and height of slope, horizontal curvature, initial stress and others. We clarified these factors are how to affect slope stability by the finite element analysis. The results may be shown below.
(1) The stress near the toe concentrates at slope angle above 45° and increases in proportion to height of slope.
(2) The slope with convex curvature in the projection to horizontal plane is more stable than the slope with straight one. This trend is remarkable when the ratio of radius of curvature to slope height is lower than 0.5.
(3) In case of high initial horizontal stress, the stress near the toe increases in proportion to the lateral coefficient K and does not increase by slope angle. And the increase of tensile stress region at the crest is easy to make crack there.
(4) As the excavation advances, the failure zone extends along the surface of slope and makes the slope unstable.

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The purpose of this paper is to choose the indicator gas components effectual for early detection of spontaneous combustion. For the purpose, 12 coal samples taken from 8 typical coal mines were heated in the air atmosphere. Then the produced gas samples were analyzed and the smells were tested at each stage of temperature. Besides 11 mine air samples taken from the places in danger of spontaneous combustion were analyzed.
From these results, it can be considered that CO, C₆H₆, C₆H₅CH₃ and C₆H₄ (CH₃) ₂ are listed as the indicator gas components and C₂H₄, C₃H₆ and H₂ are effectual only for estimating the stage of spontaneous combustion. Moreover it is considered that early detection of spontaneous combustion is generally possible by synthetic estimation of the continuous measuring data of these gas components.

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To predict the temperature of ventilation air in mines, it is essential to know the heat flow from rocks around a roadway. There have been many studies on this problem, but only a few of them dealt with the variation of the temperature of ventilation air
To predict the temperature of ventilation air in mines, it is essential to know the heat flow from rocks around a roadway. There have been many studies on this problem, but only a few of them dealt with the variation of the temperature of ventilation air
The results lead to the following conclusion;
(a) In the case of sinusoidal variation of the temperature of ventilation air, both roadway surface temperature and heat flow from rocks are calculated to a high degree of accuracy by using Eqns.(26) and (27), respectively after about four months from the beginning of ventilation.
(b) In the case of sudden change of the temperature of ventilation air, after some time from the sudden change of the temperature, both surface temperature and heat flow from rocks are calculated reasonably accurately by the method which neglects the temperature change and assumes that the temperature of ventilation air is constantly maintained at the value just after the sudden change from the beginning of ventilation.

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Several investigations have been made experimentally into the radial distribution of particles when dilute solid-liquid mixtures are carried in turbulent flow through a vertical circular pipe. It was observed that the profile of particle concentration is dependent on the particle Reynolds number and the tube Reynolds number.
In order to explain that phenomena we examined the radial position of a single particle and the peak position of particle concentration distribution in both upward and downward flow. Consequently there was nearly correspondance between their positions, therefore it was clarified that not the interaction of particles but the behavior of single particle causes the phenomena which is observed in dilute solid-liquid two phase flow. And we were able to understand qualitatively about the radial position of particles to consider the lateral pressure force and the lateral frictional force acting on the surface of a particle with regard to the lift force in a non-uniform velocity profile flow.

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The effects of floc porosity change during the process of their formation are examined using numerical solutions of Population Balance equation under Brownian coagulation.
According to the numerical experiments. the following results were nhtaineri
1) In the range represented by straight line on the Rosin-Rammler' diagram based on the weight of floc constituents, the distribution constants in both cases of Droplet model and Model 2 were seemed to he constant d urine the process of coagulation. And the distribution curves of Model 1 were represented by the combined straight lines on the diagram.
2) The decrease in number of floc during coagulation could be fitted by a second -order kinetic expression. The rate constant of Droplet model without porosity was smallest, and that of Model 2 was less than that of Model 1. These results show the effect of floc porosity change through their formation
3) When the tloc porosity is changeable during coagulation, the self-preserving spectra could be obtained by using the new similarity variables based on the weight of floc constituents.

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he dissociation reactions of both calcium and magnesium arsenates prepared by solid-solid reactions have been examined. The vapour pressure of all gas phases produced by thermal decomposition have been calculated from the results of dew noint measurement. In a similar way the equilibrium constant Kp of the dissociation reactions of both arsenates have been calculated. The results are as follows
1) The calcium arsenate and magnesium arsenate tend to dissociate at the temperature higher than about 1450°C and 1275°C respectively through the following reactions.
3MeO·As₂O₅ (s) =3MeO (s) +1/2As₄O₆ (g) +O₂ (g)....(1)
1/2As₄O₆ (g)=As₂O₃ (g)...(2)
Me: Ca or Mg
2) The relations between log K₂ and 1/T of the (1) reaction are as follows.
3CaO·As₂O₅: log Kp=-42729.4/T+16.870 (1425°-1463°C)
3MgO·As₂O₅: log K₂=-35707.26/T+17.066 (1274°-1353°C)

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Slags of the system FeO-Fe₂O₃ -CaO were equilibrated in platinum crucibles with CO-CO₂ gas mixtures at 1200 and 1300°C. The oxygen partial pressure ranged from that at iron-saturation to 0.21 atm. The results are as follows:
1) The relationships between the oxygen partial pressure and the melt composition were established and the liquidus isotherms were determined by the “Solid-Separation” method.
2) Some univariant situations in which a melt is in equilibrium with two solids were specified.
3) The equilibrium relationships between the melt composition, the oxygen partial pressure and the temperature were clarified. They were empirically fitted to a linear equatiolog po₂(atm)=5.88log(Fe⁺⁺⁺/Fe⁺⁺)-0.106 wt%CaO-(32400/T)+14.82
4) Activities of FeO (1), Fe₃O₄ (s) and CaO (s) were calculated by application of the Gibbs-Duhem equation to this ternary system.
5) The system FeO-Fe₂0₃-CaO was compared with the system FeO-Fe₂0₃-SiO₂ from metallurgical point of view.

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A simple electrochemical method has been established to detect a Cu₂O phase present or newly formed on the surface of a copper anode.Utilizing this technique, a study has been extended to investigate conditions which allow this oxide phase to form during anodization.
A well-defined peak corresponding to the reduction of a Cu₂O phase appears on the cathodic voltammetric curve provided a sufficiently fast potential-sweep rate is employed (i.e., <0.6 V/min). This reduction reaction proceeds through the following three sequential steps;{Cu₂O+2e-→2Cu°+O^2- (electron transfer)
Cu²+O^2-→CuO (rate-determining)
CuO+H₂SO₄→CuSO₄+H₂O (following reaction)
The overall cathodic reacton is expressed by,
Cu₂O+Cu²⁺+2^e-→2Cu°+CuO
and its equilibrium potential as calculated from the Nernst's equation based on the present experimental conditions is-0.42V vs. Hg/Hg₂ SO₄, which coincides very well with the experimental value.
Various anodizing conditions were given to a pure Cu anode, and analysis of the results indicates that a Cu₂0 phase only forms when the copper anode is passive.

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