In order to determine the allowable scale of mined-out quarry from the viewpointof landscape, we have been studied on two psychometrical evaluations, assuming that step-down green planting method is adopted for mined-out quarry. One is rating-scale method, and the other is choice method.
From these experiments, it is clear that allowable scale of mined-out quarry becomes smaller and convergestoa certain scale as distance to mined-out quarry is nearer. Comparing the resultsof two experiments, allowable scale of mined-out quarry by choice method is smaller than rating-scale method. But it appears that the result byrating-scale method is more reliable than choice method, considering experimental condition and so on. Anyway it becomes clear from this study that mined-out quarry needs notto be planted completely from the viewpoint of landscape, and planting cost canbe reduced.

抄録全体を表示

At the Fenton Hill Hot Dry Rock Geothermal Project in the United States, more than ten hydraulic fracturing experiments have been conducted to stimulate a hot dry rock reservoir. Two hydraulic fracturing attempts, Exp. 2059 and Exp. 2062, successfully established a large fracture system connecting an injection well, EE-3A and a production well, EE-2. The fracture systems created by the two experiments showed different fracture extension pressures. In order to understand the combined behavior of fractures, thecomputer code FEHM was used to simulate the two layered fracture system. As in part 1 of this series of papers, an exponential relation between fracture aperture and fracture pressure was used. Parameters in the modelwere fitted to simulate specificexperiments.
In this paper, the parameters were chosen to fit the data obtained from each experiment described above. The extension of each fracture was then estimated using these parameters at a constant flow rate, 0.8m³/min. Next, the fracture extension is simulated when water is pumped into the combined two-layer fracture system. From the computer simulation, the following results are obtained.
1. When two fractures with different characteristics obtained by experiments 2059 and 2062 extend at the same time by pumping water at a fixed flow rate of 0.8m³/min, the higher permeability fracture (Exp. 2059: upper fracture) extends almost at the single fracture rate, while thefracture of Exp. 2062 (lower fracture) which has lower permeability extends at half the single fracture rate. The wellhead fracture extension pressure is only 0.5MPa less than that when upper fracture extends alone.
2. By doubling the flow rate and keeping other parameters constant, both fractures extended faster and the lower fracture showed a marked increase in fracture extension rate. The results suggest that if we try to make multiple fractures along openhole section in an effort to create a large artificial reservoir, it is advisable to use the largest flow rate allowable under the given conditions.

抄録全体を表示

This paper describes a new and simple method for determination of effective porosity and tortuosity of porous media with transient gas diffusion flow through it.
The unsteady gas diffusion flow through porous media is influenced by the effective diffusivity and effective porosity void fraction. We proposed a method for measuring macropore structure by means of a numerical solution of the unsteady gas diffusion equation calculated with the finite difference method. The conditions of the numerical model, such as inlet and outlet gas concentrations at the end surfaces of the test piece, were matched with the experimental ones. The difference between the times required until the inlet concentration and outlet diffusion rates reach the halves of the steady state rates respectively was related to the macropore structures of porous media such as effective porosity, tortuosity and effective area fraction.
The present method was successfully applied to measure the diffusivity and macropore structure of fly ash-cement mortar specimens, whose composition of fly ash were varied from 0 to 40 weight %.

抄録全体を表示

The working environment in underground coal mines is dark, confined, dusty, generally hot, and includes dangerous and/or physically heavy work. Automation of underground coal mine activities would negate many of these problems. To progress the automation on longwall faces in an inclined seam, the authors have been developing Swing Phase Locomotive Mechanism as a self advancing support which has high adaptability to conditions of seams.
The mechanism and control system havebeen developed by using the experimental model WALKMINE-1 (WALKING Mechanism In Narrow Environment mark 1). WALKMINE-1 is composed of two frames which are connected by ten sub-jacks. Each frame has a base plate and an upper plate connected by two main jacks. Extension of the main jacks of both frames generates the force to press the roof and floor. During this phase, WALKMINE-1 is fixed. By releasing one of the frame's main jacks, the frame detaches from the roof and floor, and is supported by the sub-jacks. The locomotion of WALKMINE-1 is achieved by the alternate motions of the two frames. The swing phase frame is supported by thestance phase frame through sub jacks and it may move any direction with six degrees of freedom. The locomotion of WALKMINE-1 is multidirectional and has no relation to the direction of gravity.
The testing result shows that the Swing Phase Locomotion has been achieved by WALKMINE-1 with the developed control system. It could be an elemental technique for automation of the activities in underground work places.

抄録全体を表示

The removal of arsenic from hot water was investigated by the ferrite formation method. The obtained results were compared with ones obtained by the coprecipitation method with ferric hydroxide. The results are summarized as follows.
1) Magnetite is formed and arsenic is removed from hot water by the ferrite formation method. The ferrite formation method removes As (III) more effectively at 90°C than the coprecipitation method; less iron ion is needed in order to reduce the filtrate concentration to less than 0.05 mg/l. The formed magnetite particles, including arsenic, are removed by the Wet High Intensity Magnetic Separator, in the filtrate velosity of 2001/h in the magnetic field of over 0.6T.
2) The removal of As (III) and As (V) could be explained in terms of the specific adsorption of arsenic ion on the surface of magnetite. X-ray diffraction analysis showed that the lattice constant of magnetite formed by the ferrite formation method increased as the As (V) content increased. This suggests that As (V) is incorporated to some extent into magnetite.

抄録全体を表示

The extraction of molybdenum (VI) from sulfuric acid by TOA (tri-octylamine) in benzene has been investigated in terms of the effects of acid concentration. It was found that the optimum extraction occures in the range of 0.075 to 0.15 mol dm^-3 initial aqueous sulfuric acid concentration. Electronic spectra of various sulfuric acid solutions containing molybdenum (VI) was examined.
In addition, chemical method and infrared spectrum were used to examine the extracted species. It was suggested that extracted species of molybdenum (VI) formed polymolybdated ion.
On the basis of results obtained, it was inferred that molybdenum (VI) was extracted with TOA (R₃N) according to the following equation, in high concentration range of the metal.
3 [(R₃NH) ₂SO₄] + (Mo₇O₂₄H₆)⇔[(R₃NH) ₆·(Mo₇O₂₄H₆)·(SO₄) ₃]

抄録全体を表示

The anodic polarization behavior of Pb-Ag-Ca (up to 1 wt% Ag and/or Ca) tertiary alloys was determined insulfuric acid solution (150g H₂SO₄/1) at a current density of 50mA/cm² at 40°C. In addition to measurement of electrode potential and the rate of formation of lead dioxide on the alloy, X-ray diffraction analysis and SEM observation of the surface morphology were conducted to characterize the anodic oxide layer.
1) The electrode potential of the rapidly solidified sample decreased with an increase in the content ofcalcium as well as silver in the alloy.
2) Rate of growth of anodic oxide layer increased almost linearly with an increase in the content of calcium (above 0.1%) in the rapidly solidified Pb-Ca binary alloy. Alloying of a small amount of silver, 0.2%, resulted in a remarkably reduced rate of the growth of the anodic oxide layer.
3) The presence of calcium in the tertiary alloys inhibited the formation of PbO₂ up to about 0.5% Ca.
4)βA-PbO₂ was detected in the anodic oxide layer on Pb-Ca binary alloys and observed to be formed at much lower silver content in Pb-Ag-Ca tertiary alloy compared to the Pb-Ag binary system.
5) At higher calcium content and at low solidification rate, grains having high calcium content, assigned to Pb₃Ca, were crystallized and depraved the quality of the alloy anode.

抄録全体を表示

A series of experiments on the leaching of Garnierite ore with H₂SO₄ solution were carried out to investigate the effects of the some addition of fluoride and chloride to the leaching medium and roasting of the ore in air on the extraction of Ni, Mg, Fe and Si from the ore.
The addition of NaF (about 2 weight % of the ore), increase the extraction rate of Ni and Mg at 305 and 315K. The addition of CaF₂ also increase the extraction rate, but the addition of NaCl has no effect on the extraction rate.
By roasting ore antigorite, chrysotile and goethite are decomposed, to form forsterite, enstatite, hematite, magnetite, maghemite in the ore as the roasting temperature is heightened and also, free state MgO is formed in the ore, and the quantity is closely related to roasting temperature and reaches the maximum at 973K.
In H₂SO₄ leaching, the roasting of the ore significantly promotes the extraction rate of Ni, Mg, Fe and Si from the ore at 305K.

抄録全体を表示

Spent desulfurizing catalyst is valuable resouce of Mo, V, Ni and Co. Direct leaching of valuable metals from the spent catalyst is not easy, since spent catalyst as received generally contains a large amount of oily matter.
In this study, oxidative roasting of spent catalyst with Na₂CO₃ and leaching of roasted products in hot water were mainly investigated. Other sodium sources, such as NaOH and Na₂SO₄, were found to be inappropriate, since they cause a large Al₂0₃ dissolution and hazard the precipitation of molybdic acid in subsequent step. The optimal roasting results were obtained by the roasting for 2.5 hours at 1123 K with the addition of Na₂CO₃/(Mo+V)=2 in molar ratio. Leaching with hot water around 343 K during grinding can provide satisfactory leaching results for both Mo and V. Extraction of 96 percent of Mo or V is not difficult. However, the incomplete oxidation of catalyst during roasting and the holding of incompletely roasted product cause a poor extraction of valuable metals. In order to recover Mo and V efficiently in the subsequent steps, it is desired to lower S content in roasted product below 2 percent and Al concentration in leachant to be less than 2.5 g/l.

抄録全体を表示

The applications of salting-out method of ammonium meta-vanadate using ammonium chloride and acid precipitation method to recover molybdic acid by using hydrochloric acid were examined. Also, the purification of feed solution containing both Mo (VI) and V (V) utilizing weak basic type ion exchange resin was studied. Both salting out precipitation and acid precipitation methods were found to be efficient to recover Vand Mo products, respectively. The ion exchange method was also useful to remove V (V) from Mo (VI), but the separation of ultrafine solid particle formed by the control of pH of the solution was found to be important. The dilution of feed solution, however, is sometimes required. Based on the results obtained, flowsheet for practical operation was designed. The overall recoveries of Mo and V were found to be around 92%, for both metals, suggesting satisfactory operations.

抄録全体を表示