Technologies to develop the Hot Dry Rock (HDR) geothermal energy was reviewed. Since 1985, the New Energy and Industrial Technology Development Organization (NEDO) has promoted HDR project at Hijiori with the technical support from National Institute for Resources and Environment (NIRE) under New Sunshine Program. The objective of this project is to develop and confirm technologies which are required for the development of HDR. In 1991, a heat extraction test was successfully conducted with a 1, 800 m deep reservoir for three month using one injection well (SKG-2) and three production wells (HDR-1, HDR-2 and HDR-3). Water recovery during the test was about 80 % and the thermal output of the produced water and steam was about 8 MW. Deep reservoir with the depth of 2, 200 m has been developed for future heat extraction test for about two years.

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Rock mass joints are the discontinuities of intact rock in a geometrical sense, but they contain diverse attributes such as orientation, generation time, dimension, opening width, interstitial minerals, mineralogical alteration, and seepage. The value or degree of these attributes vary with joints, and therefore rock mass joints are regarded to be a multiple set. Geomathematical methods including geostatistics and fuzzy sets theory were applied to deal with such diversity of joints and to reveal the spatial distribution of joint's attributes. Two thousands of joints in the granodiorite, which were observed by the ten horizontal boring cores drilled in the two directions perpendicularly intersecting each other, were chosen for the analysis.
The semivariogram was calculated for the two attribute values based on the several joints which are supposed to be the same fracture. It was made clear that the width of interstitial minerals has the spatial correlation within the range of 20 meters. Two dimensional distribution of the width of interstitial minerals in the study area were estimated by the interpolation method termed kriging. As a result, the continuous joints with relative large width of interstitial minerals were specified and found to be oriented in the northeast and eastnortheast directions.
For the joint analysis by combining several attributes, the degree of mineralogical alteration, the width of alteration halo, and the width of interstitial minerals were selected as the attributes bearing an relation to permeability. The membership functions were defined for the three attributes respectively, and the fuzzy C-means method was applied to classify the observed joints into three groups. One group among them was revealed to have large membership values of the three attributes. Connection of the joints, which belong to this group, along their strikes made it possible to detect water channels in the study area. The seepage flow model was also constructed by a finite element method of two dimensional artesian state and the assumed transmissivity of each group's joints.

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An approach to evaluate the slope stability by the combination of field displacement measurement and numerical stress analysis is presented.
The deformation behavior of rock slope due to excavation has been analyzed by Boundary Element Method and the characteristics of the displacement field induced by bench cut excavation has been clarified. It is pointed out that the pre-calcuration is useful to select the field measurement system for the monitoring of the slope stability.
The relative displacement in rock mass has been measured in a open cut limestone mine by the use of the multi-channel-extensometer.Young's modulus of rock mass and the initial stress state in the present field have been estimated by analyzing the relative displacement induced by the excavation of one bench. Using these results, the relative displacement along the measuring line has been predicted. Comparing observed values with predicted ones, it is concluded that the rock slope is stable at present.

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Following the first report where breakdown pressurePbwas discussed proposing normalized pressurization-rate, this second report deals with the data evaluation in rock-stress measurement.
At large normalized pressurization rate, maximum horizontal stressSHwas readily calculated with the conventional criterion usingPb. From this result, sufficiently large pressurization rate, if possible, is strongly recommended. Otherwise, small enough normalized pressurization rate together with the Haimson's equation is suitable.
Reopening pressurePrgave a similar trend with minimum horizontal stressSh, though reading ofPris slightly indistinct. The difference betweenPbandPrroughly coincided with the tensile strength obtained by Brazilian test.
Several method to determine shut-in pressurePswas tried. The values obtained by Muskat and two-line methods coincided well giving slightly lower value than the first deflection point Pctc on thedt/dP-Pcurve. Pctc was approximately the same as shut-in pressure in step flow rate test, Ps_pq. It should be noted that thisPs_Pqgave a remarkably smooth distribution.
Finally, the measured rock-stress is compared with those measured by other workers.

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The inhibitory effects of fulvic and tannic acids on the cell growth, and iron and sulfur oxidation in Thiobacillus ferrooxidansandThiobacillus thiooxidanswere studied around pH 2, and compared with those of oxalic acid. Tannic acid at 500 ppm inhibited the cell growth, and iron and sulfur oxidation in 8.00×10⁹cells ofT. ferrooxidansandT. thiooxidans, more than two weeks, possibly due to its phenolic group, while fulvic acid inhibited them only within initial two days. Both were more effective inhibtors than oxalic acid.

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The present study attempts to reduce the abundance of the shredder dust from usedcars and to use it as resources effectively by converting the scrap automotive weatherstrips, which arecomposed of vulcanized ethylene-propylene-diene terpolymer (EPDM) rubbers, into reusable oily materials as softeners for the rubber manufacturing for recycling. The application of hydrothermal solution containing NaOH under supercritical conditions to this conversion was verified through batch processing experiments using a microautoclave. In this paper, the conversion of a vulcanized EPDM rubber by hydrothermal treatment was compared with that by pyrolysis at various temperature (350-450°C) and time (5-30 min). This comparison made clear differences between the cracking reactivity in hydrothermal treatment and that in pyrolysis and led to the followings:(1) Cracking was accelerated above 400°C by hydrothermal treatment, (2) Thepeak of molecular weight distribution in the high molecular weight region which originated in the crackingof the EPDM polymer shifted clearly without broadening, accompanied with the reaction time change at 420°C, (3) The milder cracking occurred in hydrothermal treatment in comparison with pyrolysis, (4) It was conceivable that hydrothermal cracking depressed the radical reaction and retained particular molecular units, (5) Carbon-sulfur linkage correlated with the cracking of the EPDM polymer, (6) Various conditions in hydrothermal treatment enables us to crack the polymer without decomposition of the softener, (7) The control of temperature and time in hydrothermal treatment can make the conversion of the rubber to oily resources with various viscosities and molecular weight distributions.

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The application of hydrothermal solution containing NaOH under supercritical conditions to convertsion of the scrap vulcanized ethylene-propylene-diene terpolymer (EPDM) rubber into reusable oily materials as softeners for the rubber synthesis was verified through batch process experiments using a microautoclave.
In this paper, the properties of resultant oily materials from a rubber by the hydrothermal treatment under supercritical conditions were compared with those by pyrolysis.In addition, effects of reaction pressure on the desulfurization, and liquefaction in hydrothermal solution and pyrolysis were investigated. These results lead to the followings:(1) Remarkable desulfurization takes place with cracking in hydrothermal solution, (2) Desulfurization and depression of liquefaction in hydrothermal solution are not caused by the increase of reaction pressure but are attributed to the characteristic reactivity of hydrothermal solution, (3) All resultant oily materials were composed of paraffinic hydrocarbons, (4) Resultant oily materials by hydrothermal treatment are more homogeneous than those by pyrolysis. The rubber compound mixed with the resultant oily material by hydrothermal treatment showed the same properties as one mixed with a paraffinic softener commercially available.
Since the resultant oily materials by hydrothermal treatment can be used as a softener in a cyclic manner, a closed rubber manufacturing process can be established. These findings and those previously reported motivate us to develop a new recycle process by hydrothermal treatment; the process can simplify hitherto known complex purification steps and facilitate the control of reactions without damaging to the present earth environment.

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Cobalt crusts were leached in sulfuric acid solution using iron (II) sulfate as reductant. Studies were conducted of the effect of various factors on leaching percentages of nickel, cobalt, copper, iron and manganese.
When the ore was leached in only a sulfuric acid solution, cobalt and manganese were little leached. Leaching percentages of nickel, copper and iron depended on the leaching temperatures. In only use of an iron (II) sulfate solution, leaching percentage of copper was less than 60%. The others were about 90%.
When leaching was conducted in dilute sulfuric acid using iron (II) sulfate as reductant, almost all of metals were leached considerably in a short time at a low temperature (30 & C). The effect of particle size was not observed.
Required amounts of sulfuric acid and iron (II) sulfate show good agreement with stoichiometric amount for the leaching.

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Leaching behavior of rare earth component used for fluorescence substance has been examined kinetically in aqueous hydrochloric acid solutions. The kinetics of leaching reaction was also investigated by changing the temperature, the stirring velocity, Cl^-ion concentration and the hydrochloric acid concentration. The leaching degree of rare earth elements used for a fluorescence substance was larger in the order of Y>Eu>La>Tb.>Ce. Yttrium and europium oxides in a fluorescence substance were dissolved parabolically with leaching time in aqueous hydrochloric acid solutions, and leaching reaction was also accelerated with increasing temperature and stirring velocity. The apparant activation energies calculated frm Arrhenius plots were 20.3kJ/mol for yttrium oxide and 18.5kJ/mol for europium oxide.According to these lower apparant activation energies, the rate-determing step of leaching reaction could be considered to be the diffusion process through Nernst's boundary layer on the surface of rare earth oxide.
From the experimental results obtained, the leaching rate equations for yttrium oxide and europium oxide in aqueous hydrochloric acid solutions could be expressed as follows: leaching rate for yttrium oxide=κ'·S'·C·V (χ)·exp (-20.3/RT) and leaching rate for europiumoxide=κ''·S''·C·V (χ)·exp (-18.5/RT), whereκ' andκ'' are a rate constant, S' andS'' the surface area, Cthe hydrochloric acid concentration, V (x) the function of stirring velocity, Rthe gas constant andTthe absolute temperature.

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To obtain the fundamental information on the dissolution of nickel and copper into the slag formed in the nickel and nickel alloy smelting processes, the phase relations between Ni-Cu-Fe alloys and FeO_X-MgO-SiO₂slags saturated with MgO were investigated under controlled oxygen partial pressure using CO and CO₂mixed gas at 1, 673 and 1, 773K
The MgO solubility in the FeO_x-SiO₂slag increased from 16 to 30 mass% corresponding to 10 and 40 mass%SiO₂ respectively at 1, 773 K.Ni and Cu are concentrated in the metal phase while Fe is distributed mainly in the slag phase under the present experimental condition. The distribution ratios of Ni and Cu into the slag increase with increasing oxygen pressure. At 1, 673 K, Ni dissolution in the slag is lower than Cu atPO₂less than 2×10^-4Pa.In the higher oxygen potential region, the Cu dissolution in the slag is much higher than Ni. Similar behavior is observed between the distribution ratios of Ni and Cu at 1, 773K
Applying the logarithmic relationship between the distribution ratio and oxygen pressure, nickel and copper form NiO and CuO_0.5in the slag equilibrated with the ternary alloys.

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