The present paper is concerned with physical phenomena associated with fluid flow in gas and powder injection in refining processes. The characteristics of bubble formation from a nozzle and an orifice (or porous plug) are described. The critical condition is discussed for jetting, in which the injected gas leaves the nozzle as a continuous jet. Dispersion behavior of the injected gas in the bath is investigated to clarify the structure of jet and plume. The stirring power of the injected gas is formulated, and the mixing time and circulating flow in the bath are also mentioned.

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Urea is decomposed to make carbon dioxide and ammonia in the solution by heating at about 373K. The reaction to produce rare earth carbonates is investigated by mixing urea solution and the organic phase containing rare earths in an open or closed vessel. Chemical and physical properties, such as surface area, thermal decomposition and shape of particles are measured on the precipitation products and the roasted products.
In the closed vessel, the reaction takes place under various conditions of urea and nitric acid concentrations with the precipitation rate of around 90%. In the open system, the precipitation rate is lower than that in the closed system. If a suitable combination of urea concentration and nitric acid concentration is selected, it is possible to obtain the precipitation as high as 60% even in the open system. The obtained precipitation products are found to be rare earth carbonate hydrates and to be easily converted to rare earth oxides.

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Separation of rare earths, especially Nd and Sm, was investigated by a batch and column method with solvent impregnated resin. The solvent impregnated resin was prepared by an impregnation of organo-phosphorous extractant whose trade name was PC-88A into a porous polymer resin.
Though PC-88A is an effective extractant for rare earth separations, the adsorption behavior of rare earths with solvent impregnated resin in a batch method is the same as that with solvent extraction. In a column method to separate Nd and Sm, the effective separation in both adsorption and elution processes can be attained by setting suitable conditions, such as a bed hight, a flow rate and a concentration of eluant. Neodymium which is a lighter rare earth is separated from Sm at an adsorption step, while Sm which is a heavier rare earth is recovered at an elution step. From the integration on breakthrough and elution curves, yield of Nd and Sm is calculated in the condition of 100% purity. The solvent impregnated resin can be repeatedly utilized at least 20 times from the results of life test of the resin.

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In this study, time-dependent strength of granite was interpreted in terms of micro-structure model.
Using Kemeny's model, strength realized in monotonic loading test, creep test and cyclic loading test under uniaxial compressive condition was calculated and compared with the experimental results. In this model, the rock is assumed an elastic medium containing a column of sliding cracks and the cracks grow due to stress corrosion. It was confirmed that this model is able to precisely represent the effect of loading rate on compressive strength and the creep strength. However concerning on the fatigue behaviors, time to failure was overestimated when stress amplitude became large.
Therefore, we have modified Kemeny's model, where the coefficient of friction of sliding cracks was reduced gradually under cyclic loading. It was found that this modified model was able to explain the effect of stress amplitude and maximum stress, quantitatively. It was also found that the effect of loading frequency on the fatige strength was similar between the prediction and experiment.

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In order to enhance the safety in ventilation, a ventilation transition diagram was derived from the macroscopic characteristics of a complex ventilation network.
Main results are as follows;
1) The combination of two branches with linear relationship in airflow rates can be detected by computer simulations varying aerodynamic resistances of each branch in the network.
2) Airflow rates in a specified branch, coal face, advancing face, etc. are given as a linear function of the airflow rate in two branches with a regulator.
3) The airflow rate in a specified branch can be controled using a ventilation transition diagram, which has a coordinate of airflow rates in two branches with a regulator and the airflow rate in the specified branch as a parameter.
4) A safety factor in the specified branch can be estimated by a decreased value of methane concentration with increasing airflow rate in the ventilation transition diagram.
5) The ventilation transition diagram, which shows changes of the airflow rate/direction in the network, can be utilized to decide the possible evacuation route in case of spontaneous combustion, mine fire and so on.

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Wind effects on the measured values by a dust sampler LV-5E are inspected in a laboratory wind tunnel. The wind direction was set at angles of 0°, 45° and 90° to the respiration direction. The wind velocity was changed from 1.0 to 5.0m/s. The results are that respirable dust values are not affected by the wind direction and the velocity, but total dust values tend to be reduced with increasing angles of the wind direction. When the wind velocity increases, the reduction of total dust values become more remarkable.
On-site experiments in coal mines showed similar results as in the laboratory experiment.

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The authors have recently proposed a criterion for brittle rock fracture named tensile strain criterion, which based on Bridgman's maximum tensile strain theory and represented by the equation given below;εT=εTC (1) where εT is tensile strain and εTC is critical tensile strain at a maximum load. Eq.(1) means that failure occurs when tensile strain reaches critical tensile strain.
Preliminary tests using Sorachi sandstone and Shinkomatsu andesite have revealed that critical tensile strains under uniaxial compression and diametral compression are equal to each other and that critical strain does not depend on confining pressure in triaxial compression test.
These results are further confirmed for several kinds of rocks. In addition, the following results are newly obtained:
1) Strain rate does not affect critical tensile strain.
2) Critical tensile strain could increase with ductile deformation under relatively high lateral stresses.

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The supersonic fire jet burner is used for piercing of rocks and concrete structures, and for drying-degradation of fine particles. One of the methods for intensifying the efficiency of this burner is to make the pressure in a combustion chamber higher. In the high pressure (10-30 atm) jet burner, the process of burning is supposed to be different from that of low-pressure (about 7 atm) jet burner. In order to find the optimum configuration of the jet burner, the authors made the experiments on the size of combustion chamber and the swirler construction. The heat loss to the cooling water and the generation of the soot in a flame were used for the assessment of the operation of the jet burner. The ratio of characteristics length/diameter of the combustion chamber, volume of the combustion chamber, the jetting angle and the deviation angle of a swirler for the good burning were obtained.

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A series of experiments were carried out on the production of fine palladium powder by reducing an aqueous solution suspending diamminepalladium (II) chloride (Pd(NH₃)₂Cl₂) powder in a hydrogen gas bubbling batch reactor at a temperature of 293K and under a pressure of 1.0×10⁵Pa. On the basis of the results, the reaction mechanism and the morphologies of the products were studied.
The reduction of the solution containing dissolved palladium as Pd(NH₃)₄²⁺ and suspended Pd(NH₃)₂Cl₂ proceeded linearly with reaction time. The rate of reaction was 2.3 times that of the solution containing palladium only as Pd (NH₃) ₄²⁺, and was about the same value as that of the solution suspending Pd(NH₃)₂Cl₂ and not containing Pd(NH₃)₄²⁺. The pH and the concentration of the Pd ion in the solution maintained constant values throughout the reduction period. The behaviors showed that the reduction of Pd(NH₃)₂Cl₂ powder occurred prior to that of the Pd(NH₃)₄²⁺. It was presumed that the reaction proceeded by reducing Pd²⁺ that was dissociated from Pd(NH₃)₂Cl₂ in the solution.
The forms of the particles obtained by the hydrogen reduction of the suspended Pd(NH₃)₂Cl² were granular with diameter of 1-3μm and the morphologies were much different from those of porous particles obtained by the hydrogen reduction of dry Pd(NH₃)₂Cl₂ powder. By adding a surfactant to the solution, mono-dispersed spherical particles were produced.

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One step and two step treatments with Na₂B₂O₄, Na₂B₄0₇ and Na₂B₆O₁₀ fluxes for the production of purified hematite from iron oxide produced in the residue treatment process to precipitate iron (abbreviated as IR-oxide) and various iron ores have been investigated by use of the recrystallization method.
And, the effects of the iron ore/flux ratio, the sort of fluxes and the number of treatment on the removal of impurities in iron ores and the yield of hematite crystal were tested.
The main results obtained are as follows:
(1) The concentrations of Si, Al, Mn, Mg, Ca and V elements decreased with the flux treatment regardless of sort of ores. But the degree of Mn removal was low, and Ti was not removed.
(2) Two step flux treatment of iron ores was more effective than one step, except for removal of As, S, Si and Ti.
(3) On removal of impurities in iron oxides, Na₂B₄0₇ and Na₂B₆0₁₀ flux are superior to Na₂B₂O₄, and Na₂B₄0₇ is suitable for the removal of Si, Al, As and S, while Na₂B₆0₁₀ for the Mn, Mg and Ca removal.
(4) Mixing amount of 35 mass% iron ore gave the better removal. rate of impurities by the flux treatment than that of 45 mass%, whereas the better yield of hematite crystals was obtained in the case of 45 mass%.

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The authors developed a non-destructive method to measure depth of crack appearing on rock surface, which utilizes change in polarity of first motion of diffracted P-wave.
The following results were obtained through experiments using mortar specimens:
1) Depth of slit and artificial crack as deep as 10 cm could be easily and rapidly determined.
2) Depth of water-filled slit could also be measured.
3) Angle of inclined slit could be measured.
Results of in-situ tests for three types of rock, namely, sandstone, tuff and granodiorite are as follows:
1) Depth of crack as deep as 80 cm could be easily and rapidly determined.
2) Angle of inclined crack could be measured.
3) This method could be applied for cracks which are parallel to the measuring surface.
4) Depths of tightly closed cracks could not be determined by this method.
5) Depths of all cracks could be determined for granodiorite. For sandstone and tuff, however, depths of about a half of cracks could be determined.

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Underground Coal Gasification (UCG) is one of the methods to recover energy from underground coal seams. In 1970's and 1980's many basic studies and field tests on UCG were carried out in USA. Although the activity on UCG is now interrupted, because of the recent energy market situation of low oil price in the world, the developed technologies and concepts in this period is remarkable. Since 1960's almost no studies on UCG were made in Japan.
The authors made a feasibility study on UCG in Japan, in applying the new USA and data obtained in the field tests. This study includes the best site selection for UCG in Japan from the view point of geological conditions, the prediction of product gas component and the cost estimation. Two UCG methods, ELW (Extended Linked Well) and CRIP (Controlled Retracting Injection Point), were considered for cost comparison. One million tons of coal were planned to be gasified in 10 years. The production cost of gases per heating value was estimated to be between 0.012/kcal and 0.019/kcal.

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The direct use of air drawn from an abondoned mine to provide a source of heat in the winter and to control the temperature rise due to solar insolation in the summer are investigated.
The horizontal land has been made by burying the valley near Shirataki Mine in Ohkawa Village, Kohchi prefecture, with the waste rocks which had been produced through mining. Then the green houses have been built and hydroponic cultivation has started. In order to reduce heating requirements for greenhouse, it is intended to use air ventilation through a part of the mine which was once closed.
The authors have developed a computation system to predict the seasonal variation of positional distributions of underground climate with time passage after first ventilated. The computation by the system has been carried out on a personal computer and the computation results demonstrate that ground conditioned air is available for temperature control in the limited number of the greenhouses if transportation pass from the mine outlet to the greenshouses is very short or thermally isolated.

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Reduction of Ag, Cu and Au from aqueous solutions by hydrogen absorbed in mono-dispersed fine spherical palladium powder were investigated. The hydrogen was absorbed in the palladium suspended in water under the temperature of 293K and the hydrogen partial pressure of 1.0×105 Pa, and then the reactant solution containing AgNO₃, CuSO₄ or HAuCl₄ were added at 293K. The reaction finished within 0.9 ks and the reduction extent increased with the quantity of the hydrogen absorbed in the palladium. The products were spherical composite powders coated with Ag, Cu or Au on the palladium surface.

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Experiments on dissolution of Ir and Os in 1N and 3N HCl solutions were carried out using a Teflon reaction vessel maintained at 150°C over 150 days. We obtained high concentrations of Jr and Os, in relatively low pH, high oxygen fugacity and highly saline conditions. For instance, Jr concentration in a solution with 3N HCl as the starting condition reaches about 1, 800ppm, and Os concentrations in solutions with 1N and 3N HCl as the starting conditions reach, in both cases, about 800ppm. These high concentrations of Jr and Os are believed to be due to the stable existence of Ir⁴⁺ and Os⁴⁺ chloro-complexes in the solution which was clarified by UV and visible absorption spectra, and due to degassing of H₂ from the system, which gives a rise to the decomposition of H₂O. On the basis of the results of the present experimental work and those on the platinum dissolution in HCl solution obtained by Honma et al., we suggest that if the conditions for the formation of hydrothermal origin of Pt-group metals deposits are present, conditions of low pH, high Cl^- concentration and oxygen fugacity are favorable for the formation of Pt-group metals, and chloro complexes of Pt-group metals are stable in the ore fluids.

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