A new process for production of electrolytic nickel was developed by Sumitomo Metal Mining Co., Ltd. The process employs chlorine leach of nickel matte and electrowinning of nickel from chloride solution. Traditional chlorine leach with relatively low recovery of nickel and sulfur has been innovatedby the research. A counter current leach in the closed circuit was established. The plant employing core technology developed was constructed with a capacity of 330 t-Ni/M in 1989. The following continuous operation served as a good proof that all of the steps comprising the process were practically established. In 1991, construction of the commercial scale plant was commenced and the operation started in 1992. The plant has been successfully practiced and demonstrated superior performance. The matte refining process was finally shut down as all replacement was completed in 1993. The Sumitomo's MCLE process covers the following technical features.
1) Application of the MCLE process has increased the production capacity to 2, 300 t-Ni/M even though only the North Tank House is in use.
2) Over all recovery of nickel is improved due to a decrease in the process middling.
3) Quality of the electrolytic nickel is superior to that of our conventional matte electrorefining process. This is attributed to improvement of quality control by employing DCS and the on-line analysis.
4) The existing South Tank House and pyrometallurgical operations originated with the matte electrorefining was shut down and it has led to tremendous man power saving. MCLE has been established as a new highly efficient process for nickel production. This process achieves high productivity and overall cost saving on electrolytic nickel production and, improves working condition and environmental management.

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Natural gas is quickly moving away from its past image of poor relative of the hydrocarbon family towards a much more powerful position in the primary energy resources.
Natural gas now occupies about 20% share of world total primary energy supply, compared with 40% share for oil. It is true that natural gas industry started its commercial activities in 1950's much later than oil business that was initiated in the mid of the 19th. century. Therefore, exploration and development for natural gas have not been matured yet so that its reserves assessment may be still ambiguous. By reviewing widely available statistical data, this paper presents mostlikely reliable assessments as of 1992 end for the world conventional natural gas regarding the ultimately recovrable resources, cumulative and yearly productions, remining proved reserves as well as the assessment of undiscovered resources. Finally, eight unconventional gas resources such as (1) Tight Formation Gas, (2) Geo-pressured Gas, (3) Gas Hydrate, (4) Coal Bed Gas, (5) Oil Shale Gas, (6) Biomas Gas, (7) Swamp Gas, and (8) Deep Earth Gas are briefly introduced for the future potential of natural gas energy.

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Adsorbing capacity of algae for gold ion was largely improved by pretreating the algae by hot water leaching in an autoclave. By this pretreatment, the adsorbing capacity of brown algae for gold ion increased by twice or more. After the pretreatment, soluble substance was removed by hot water, and the apparent density of algae was decreased. By the photomicrograph and SEM, indentations were observed on the surface of the pretreated algae. Surface area of the pretreated algae per unit mass is supposed to be much larger than that of the untreated algae.

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The mechanical and hydraulic properties of joints included in rock masses are affected significantlyby geometrical characteristics of the two surfaces making up each joint. It is recognized that the amplitude of seismic waves transmitted across a rock joint is more sensitive to changes in the joint properties than the velocity of transmitted waves. In this study, the real area of contact between the two surfaces of a joint under normal stresses is examined by means of measurig the amplitude of seismic waves transmitted across the joint. Seismic experiments are conducted using a joint model which consists of a single aluminum plate (2mm in thickness) ranging from 10mm to 50mm in diameter inserted between two cylindrical aluminum blocks (50mm by 50mm) or consists of multiple plates with an identical diameter of 10mm. It is shown from the experiments that seismic waves transmitted through the joint model attenuates monotonously with decreasig the total contact area of plate (s). Then the relationship between the amplitudes of seismic waves and the contact areas is given by A/A₀=α^0.75, where A₀ is the amplitude of seismic waves transmitted through the no-joint model, A is that of seismic waves through the joint model, and α is the ratio of contact area to the cross- sectional area of the cylindrical blocks. The reason for the equation being non-linear is that the energy of seismic waves passing through the central part of the circular section is greater than that of seismic waves passing through the outer part, which is caused by the difference in diameters between the joint model and the transducers. Thus the above relationship is valid only for the present measuring system. With the seismic measurements, three series of uniaxial loading are conducted on an artificial rock joint under mated and unmated contact conditions. The real contact areas estimated using the equation are 90% and 11% for mated and unmated conditions at the normal force of 12kN, respectively. The difference in contact areas is also reflected in the normal force-closure behaviors.

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Various methods of estimation of methane gas content in coal seams have been developed. The direct method of the US. Bureau of Mines is popularly used in the United States, Australia and Europe. Other methods were proposed by French National Coal Institute and German Mine Ventilation Institute. In this paper, the measurement results of some Japanese coal seams based on the measurement method of US. Bureau of Mines are described. Lost Gas were estimated by three methods which are, √t equation, Aiey's equation and Darcy's equation. In results by three equations, the highest value was one estimated by Aiery's equation. The lowest value was estimated by Darcy's equation. It can be concluded that the best estimation method of Lost Gas is the method by Aiery's equation, though it is impossible to estimate the Lost Gas of some coal samples. Therefore, Lost Gas should be estimated by Aiery's equation and √t method. If measurement of desorbed gas can be done several times in the initialstage, the value estimated by√t method will be approximately equal to one estimated by Aiery's equation.

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Zinc, which has stronger affinity for oxygen than iron, has to be selectively reduced in the ISP furnace. Consequently, a considerable amount of zinc remains in slag. Higher temperature promotes the reduction reaction of zinc oxide with CO gas because of the endothemic nature of the reaction while the reduction of iron and lead oxides with CO is exothermic. To investigate the temperature effect on zinc and lead reduction, equilibrium experiments between the CaO-SiO₂-FeO_x slag and molten lead and the distribution experiments of zinc between the slag and molten copper were performed in iron crucibles in temperature range from 1, 473 to 1, 673K. The lead solubility in the slag of %CaO/(%CaO+%SiO₂) =0.42 is 0.1 to 0.2%, which is the minimum solubility by CO reduction. The Pb0 activity coefficient for the slag of %CaO/(%CaO+%SiO₂) =0.42 varies from 1.0 to 1.8 with increasing iron oxide content from 30 to 50%.The ZnO activity coefficient for the slag increases also with iron oxide content but decreases with increasing temperature. The ZnO activity coefficient for the CaO-SiO₂-FeO_x slag varies from 0.5 to 4 at 1, 573K and increases with increasing slag basicity. When temperature rises by 100 degrees under iron saturation, zinc content in the slag reduces by 50%. Zinc vapor pressure of about one atmosphere from the slag produced in the hearth of the ISP furnace is estimated at 1, 623K under iron saturation.

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The authors have developed a computing system for 3 D analysis by combined Fictitious Stress and Displacement Discontinuity Methods with Joint Elements. In the system, the boundary surface of an underground cavern is divided into triangular leaf elements and the constant fictitious stress componentsare distributed over each element. The joint having some thickness is divided into triangular pillarelements which consist of soft elastic mateiral and the constant displacement discontinuity components (normal convergence and transverse dislocations) are distributed over each element. The solution procedure is briefly presented first and it is applied to two practical problems on underground excavation next. Applicability of the procedure is demonstrated by comparing the excavation-induced displacements around a large rock cavern, the excavation-induced convergences between the points on tunnel boundary and total stress distribution on the tunnel wall which are numerically calculated by the procedure, with those practically observed in-situ.

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The present paper describes kinematical solutions to both ordinary and inverse probiems of the manipulator mounted on a prototype of shotcreting machine. Also derived is the equation of motion which describes dynamics of the manipulator consisting of four links connected in series. These solutions and equation provide a basis for robotics of this machine, and control schemes as well. Since the manipulator of this machine is actuated by hydraulic cylinders and a pump, the hydraulic systems are also taken account to modelling of the manipulator. A control scheme of combining feed-forward and feedback is adopted to control the manipulator so as to displace faithfully along planned paths. A computer simulation suggests that the feed-forward control scheme with PID feedback should be valid for controlling the manipulator even if its motion was associated with some disturbances caused by jetting out shotcrete from the nozzle. The simulation has also shown that the control scheme may be tolerant for inaccuracy accompanied by modelling the mechanical and hydraulic parameters included in the system.

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Ohyama's critical current density, at which Zn began to deposit on pure Zn cathode from the electrowinning solutions containing an impurity, was studied by comparing its magnitude with Tainton's critaical current density at which Zn began to deposit on impurity metal cathode from the impurity-free solutions. According to the electrochemical requirement, previously reported by the present authors, for the initiation of Zn deposition in the presence of more noble hydrogen ions, the critical current density unequivocally depends on the minimum hydrogen overpotential, η⁰_H, of cathode substrate. Therefore, the impurity in the solutions should change the magnitude of the critical current density either by depositing to alter the η⁰_H or by acting as a catalyst to reduce the η⁰_H of original Zn cathode. Then the electrochemical behavior of the impurities was estimated, and it was found that the Ohyama's critical current density was closely related to the behavior of the impurities at lower current densities than the critical current density.

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Simulation of upward solid-liquid flows in a vertical pipe was conducted. Trajectories of particles were obtained by means of the Lagrangian method with a collision model including inter-particle collisions and particle-wall collisions. Local mean velocities of the liquid phase were calculated numerically from the equations of continuity and motion by the SIMPLE scheme. The flow and collision were treated two-dimensionally. Three modes of calculation were conducted: non coupling, drag force coupling and coupling with both the drag force and the fraction of the fluid. The three calculations resulted in quite different concentration distributions. The effects of inter-particle collisions, particle properties, flow conditions and time intervals on concentration distributions of the particles were examined.

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The rare earth magnet has a good performance, and the production is increasing year by year. Two types of rare earth magnets are presently made as industrial products. One is a Nd-Fe-B intermetallic compound magnet and the other is a Sm-Co alloy magnet.
Mixed scraps of Nd-Fe-B intermetallic compound and Sm-Co alloy are sometimes produced in the step of production. Therefore, it is desired that the recycling system of mixed rare earth magnet scraps shall be established.
In the present study, the extraction and separation of Nd and Sm by solvent extraction is mainly tested to obtain the fundamental data for the hydrometallurgical treatment of the mixed rare earth magnet scraps. The results obtained in this study are summarized as follows:
(1) The separation efficiency of Nd and Sm from hydrochloric acid solutions is better than that from sulphuric acid solutions.
(2) The extractant combinations, EHPNA/ TOPO and EHPNA/TOA are favourable to the extraction and separation of Nd and Sm, compared with other extractants tested in this study.
(3) The hydrometallurgical process of mixed rare earth magnet scraps based on oxidizing roasting, hydrochloric acid leaching, and solvent extraction is proposed.

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The Bayer process on alumina production has exhausted so far a great amount of red mud unutilized. It is then desirable to recover such valuable elements as titanium and zirconium from the red mud. First, we could easily decompose and remove sodalite in the red mud with diluted sulfuric acid at room temperature. Further leaching was applied to the pre-leached red mud with sulfuric acid (0.5-2.0mol/l) at 120°C. The dissolution of hematite, a main component of the red mud, enriched acid resisting minerals such as anatase, zircon, quartz, and other insoluble elements by eight to ten times. This experiment resulted in 74% of TiO₂ and 4.5% of Zr0₂ in the leached residue and enriched also yttrium and niobium by twelve times. We finally applied the alkali-fusing to the red mud to remove Si0₂ out of the residue and successively leached the fused cake with water. In this procedure, 60% of quartz was removed and titanium oxide was enriched to 84%.

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There have been proposed several stress analysis-base methods to predict microseismicity induced by deep mining. In this paper, a method named “seismic moment method” is modified to be able to take into account coal seam fracturing. Accuracy of this method is compared with conventional methods for case on the deep coal mining at Horonai coal mine. It is recognized that this method is the best to predict areas where microseismic events densely distribute, quantitative intensity of microseismicity and its variation with face advance.

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