The sulfurs in coal are classified into two forms, organic and inorganic. There are large differences between organic and inorganic sulfur in the microbial desulfurization from coal.
Organic sulfur exists as thiophen, aromatic sulfide and thiol where sulfur makes a chemical bond with carbon as a part of coal structure. Therefore, organic sulfur would appear on the coal surface at very small ratio, and usually be burried in the coal bulk, even though the coal were ground into fine particles. It is very difficult to remove organic sulfur biologically, because the microorganism can not invade inside of coal structure to attack the sulfurs. In order to remove the organic sulfur, the liquefaction of the coal would be requested for the microbial attack.
On the other hand, inorganic sulfur exists as crystal of mineral, mainly pyrite. And inorganic sulfur would be separated from coal as pyrite particles by pulverizing coal to fine particles. And then the microorganism can attack pyrite and oxidize it to ferric ion and sulfuric acid. It was called bacterial leaching. However, this leaching method would be infeasible to treat huge amount of coal in short term. The microbial flotation method has been developed for the solution of the disadvantage, as quick desulfurization method.

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In order to investigate the effects of pore fluid pressure and strain rate on mechanical behavior of rocks under stress, laboratory experiments were carried out using the porous specimens of Noborobetsu Welded Tuff. In this study triaxial compression tests with a conventional hydraulic testing machine were conducted for two types of the welded tuff specimens, which have different physical properties, confined pore water pressure or pore gas pressure under the strain rate from 10^-5/sec to 10^-3/sec. From the stress-strain curves determined under these conditions, following results were obtained:
The effective confining pressure law which was confirmed based on fracture and deformation behaviors in the region of pre-failure on the stress-strain curves was valid for two types of the welded tuff specimens under the strain rate ranging from 10^-5/sec to 10^-3/sec.
In pore fluid pressure tests, the increase of the strain rate affected the deformation behavior of the postfailure region in the stress-strain curve under the low effective confining pressure.

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Rock slopes are often associated with the construction of highways, hydroelectric-power plant, atomicpower station and open-pit mining. As varieties of discontinuities (e.g. joints, bedding planes, etc.) exist in the natural or the excavated rock slopes, the stability of rock slopes is heavily governed by the geometrical distribution and mechanical properties of discontinuities. Especially, when the rock slopes are dominated by the subvertical discontinuities, toppling failure phenomena is likely to occur. Nevertheless, it is difficult to make the quantitative evaluation of the mechanism and failure process of toppling in discontinuous rock slopes with such a method founded by continum mechanics, while the conventional numerical methods such as the finite element method (FEM) and the boundary element method (BEM) have been frequently used to simulate discontinuities by joint element.
In this paper, the toppling failure of discontinuous rock slopes are discussed using the distinct element method (DEM) and the experimental approach. The failure modes and failure process calculated according to the DEM are compared with those of experiments carried out using newly developed base friction apparatus. The model in the experiment is constructed by an assemblage of blocks composed by gypsum, slaked lime and water. The blocks are arranged to generate the cross-continuous orthogonal-discontinuity sets or intermittent orthogonal-discontinuity sets. This analysis regards that the toppling failure is related to the spacing, persistency and orientation of discontinuity plane along with the natural slope. Influences of these parameters on slope stability are analyzed and discussed in detail.
In relation to the toppling failure, the numerical analysis agrees well with the experimental model. The results obtained in this study clearly indicated that the toppling failure is mainly governed by the geometrical arrangement, frequency and mechanical properties of the discontinuities than other parameters. The higher the frequency of discontinuites, the more the possibility of toppling failure. Especially, if only changing the frequency of the discontinuities, the unstable area increases and there would be a limitation for the frequency of the discontinuities against the toppling failure.

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Cyclic loading tests on Inada Granite were carried out under 0, 5 and 25 MPa of confining pressure to examine the next two effects: the effect of confining pressure on the characteristics of strength and deformation; and the effect of stress amplitude on fatigue life. The main results are as follows.
1) The fatigue strength rises as the confining pressure is increased. However, the rate of the increase of the fatigue life N_f to the decrease of the maximum differential stress σ_Dmax is almost identical despite of the different level of confining pressure. A same curve can represent the relationship between σ_Dcσ_Dmax (difference between static strength σ_Dc and σ_Dmax) and log N_f under the two levels of confining pressure (5, 25 MPa). That is, this curve can be used to predict the fatigue strength from the static strength.
2) Three stages, namely. transient, steady and tertiary stage, are observed in fatigue deformation. Under the 25 MPa of confining pressure, the transient stage is shorter and the steady stage is relatively longer. As the confining pressure is increased, dilatant strain is restrained and the rate of the increase of volumatric strain per one cycle decreases.
3) When the maximum differential stress is fixed at a constant value, the fatigue life increases as the stress amplitude decreases. This tendency becomes more evident as the value of the maximum differential stress becomes lower.
4) When the maximum differential stress in fatigue tests and creep tests are the same, time to failure in fatigue is shorter than that in creep in the range of the maximum differential stress lower than a certain point.

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A hydraulic fracturing test was conducted in 1992 at the Hijiori hot dry rock test site. In this test, water was injected into injection well HDR-1. The depth of the injection well was about 2, 200m, and the maximum ternperature of the well was about 270 degC. The main fracture, which was extended along natural joints, was initiated from the bottom hole and a radius of the fracture was estimated to be about 500m from the acoustic emission observation. In this paper, the radius of the fracture, and the pressure, permeability and aperture distribution within the fracture was estimated by numerical simulation. The FEHM (Finite Element Heat and Mass transfer) code was used to estimate the radius of the growing fracture and a pressure distribution within the fracture. The Gangi bed-of-nails model was used to relate the fracture aperture to the fluid pressure. The permeability of the fracture was then calculated from the fracture aperture using Lomize's friction factor. A pressure history match between measured and calculated value was obtained. The simulation result shows that the radius of the fracture at the end of the experiment was about 500m, which agrees well with observations. The estimated apertures of the fracture at the vicinity of the well were 1.4mm and 2.6mm when the injection water rates were kept constant at 6kg/s and 20kg/s, respectively. In this simulation, three fitting parameters were used to match the pressure history. The sensitivities of three parameters on the simulation results were also examined.

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The investigation of time-dependent strengh of rock containing cracks is considered important in designing underground structures required to remain stable for long term. Hence, rock specimens containing cracks (fractured rock) artificially induced by heating procedure were at first prepared in this study. Then, the timedependent behavior in such rock specimens under uniaxial compressive stresses was examined in both dry and water saturated conditions.
As a result, it was shown that the strength of closely fractured rocks depends on the loading rate irrespective of the kind of rock or dry and wet conditions, and also that the loading rate a is related to the impulse I to the failure as given in the equation (2). Finally, it was confirmed that the micro-structure model proposed by Kemeny can be applicable to even fractured rocks.

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There are many ventilation networks utilizing multiple fan system. Not only the airflow distribution analysis but also the optimization of such ventilation networks are affected by the interaction of these fans. This paper describes the influence of the interaction of fans on the optimization of the network.
Firstly, fundamental procedures for the optimization of multiple fan network are explained. They are similar to those for a single fan network, the interaction of the fans interferes the convergence of the analysis to the optimum conditions depending on the configurations of the network and fans. The economical conditions of such a procedures will be deduced theoretically.
An improved method for optimization of multiple fan network system in various condition is developed on the basis of the theory. Finally, criteria for checking the optimization of a multiple fan ventilation network is proposed and several examples of the application will be shown.

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The adsorption phenomena of sodium pyrophosphate and sodium silicate were studied on synthesized diamond and unreacted graphite. Both depressants adsorbed on diamond surface, while they were rarely onto unreacted graphite. It suggests that the diamond surface adsorbed with depressant becomes hydrophilic to depress the floatation of diamond. The adsorption isotherm curves were also measured to estimate the differential heat of adsorption. They were between the typical values corresponding to physical and chemical adsorption. The dependency of adsorption density for these depressants on pH showed as follow: primary adsorption species was HP₂O₇^3-and adsorption isotherm equation was of Langmuir type for sodium pyrophosphate, while it was SiO (OH) ₃^- and Freundlich type for sodium silicate.

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Lithium was collected from an artificial ocean current by using an adsorption plate method. For this experiment, 30 tons of sea water were transported to our laboratory from Beppu Bay, Japan and an artificial ocean current was generated in a circulating water channel. We used an adsorption plate made from acrylic plate onto which an oxygen-manganese type powder adsorbent was applied. The experimental results are shown as follows:
(1) It was confirmed that over 400mg Li were collected per unit square meter of adsorption plate, after 60hours, in an artificial ocean current of 125cm/sec. This amount of Li is equivalent to the Li content of 58g spodumene, which is the most popular Li land ore.
(2) The rate of Li adsorption depended significantly on the ocean current velocity. Therefore, in our opinion, an industrial Li collection plant should be constructed at a sea area where exists a natural ocean current, such as the Kuroshio current.
(3) The Li collecting ability of the adsorption plate was maintained throughout 16 tests of Li collection from the ocean current.

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Changes of the matte grade and oxygen pressure during the slag making stage in a PS copper converter were calculated by equilibrium calculations. In the calculation a slag making stage was simulated by many calculation steps in series, each of the steps being assumed in an equilibrium state. Results of the calculation were compared with experimental values measured in pilot and commercial converters.
1. Calculated and measured matte grade changes were in good agreement with each other during the slag making stage. In particular, both of the changes showed that in the beginning of the stage there was a period of time for which the matte grade did not increase appreciably in spite of blowing. According to the present calculation, this was attributed to an increase of oxygen disolved in the matte.
2. Calculated oxygen pressures at the beginning and the end of the stage agreed relatively well with those measured for the matte before blowing and for the converter slag after the stage, respectively. However oxygen pressures measured through the converter mouth during the stage were rather higher than those predicted by the calculation. Some of the measurements gave higher oxygen pressures than those measured even at the end of the stage.
3. To explain the above mentioned phenomena by equilibrium calculation, a two-zone converter model has been developed. In the model the matte holding zone in a converter consists of two zones, i. e. a magnetite formation zone and a magnetite reduction zone, which are assumed in a different equilibrium state. By setting a proper ratio of the two zones, differences in oxygen pressure between the white metal and the converter slag at the end of the slag making stage were explained to some extent.

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Experimental attempts and computer simulation for Addox reaction (Inverse redox reaction by ion exchange) have been achieved in order to elucidate the additivity of intensive valiables and apply to energy recovery of separation processes. The ion exchange resin of benzimidazole radical was prepared for this experiments. Equations applied to computer simulation were newly introduced. One was introduced for the calculation in a equilibrium stage and the other was for conversion by computer. Ferrous ion reduced VO (IV) and TiO (N), whereas the standard redox potentials of VO (IV)/V (III), and TiO (IV)/Ti (III) are lower than the potentials of Fe (HI)/Fe (II). The inverse redox reaction ratios were proportional to the intensive valiables differences. The calculated values by computer simulation were coincident with the experimental data and it was very useful for the analysis of the experimental results.

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