The residual reserves of oil and natural gas in the world are able to be mined for only about 40 and 60 years. On the other hand, it is estimated in the long-term future that the thermal nuclear fusion will be utilized to the main energy, and that the atomic power generation and another natural energies will be utilized to the supplementary and local energies.
Coal is reserved over about 11 trillion tons in all the world and about 15 billion tons in Japan. In Hokkaido iland, coal is reserved about 8 billion tons and coal seam methane is reserved about 300 billion m³. But the amount over 90 % of these coal and coal seam methane can not be mined by the now technologies.
The auther evaluates the now mining technologies and utilizing purposes of coal seam methane, and proposes the following items.
(1) From the viewpoints of the available utilization of fosile resources and the groval environments, the coal seam methane have to be utilized to the energy resources of fuel cell etc. and the raw material of chemical products.
(2) In order to mine and utilize the native coal seam methane that are reserved in japanese interior, the inovatie mining and utilizing technologies have to be researched and developed in Japan.
(3) These researches and developments have to be enforced at once by Japanese Gavernment.

抄録全体を表示

In this paper, productions and prices of metals in 1990's were analyzed. Six metals, aluminum, copper, lead, nickel, tin and zinc, were analyzed. The production levels of these metals were almost flat until 1995 and increased after that. The price levels declined until 1993 and climbed during 1994-96. However, the price levels sharply dropped during 1997-98 due to the international currency crisis. After 1999, the price levels were in rising trends corresponding to the recovery of the world economy.
The relationships among the productions, prices and the world GDP were analyzed using the regression models. The findings of the paper were as follows.
i) Except tin, the production levels were explained by the prices level of 2 years ago. If the prices were higher than the trend values, the productions in two years later would increase.
ii) The growth rate of the world nominal GDP significantly affected to the price levels of aluminum, copper, lead and nickel.

抄録全体を表示

A new method called the Stress Compensation-Displacement Discontinuity Method (SC-DDM) is proposed for the Homogenization Analysis of 2-dimensional Multi Joint Set Problem.
Mechanical behavior of the rock mass which contains many joint sets within is dependent upon the joint set geometry and condition, such as the number of joint sets, the joint length, the joint interval, the aperture of joint and so on, and concerns with the loading condition including the orientation of loading. In order to analyze the mechanical characteristics of such a rock mass, the homogenization is successfully applied in the present paper, together with a stress compensation scheme. An infinite structure of rock mass is homogenized using a unit cell which is a representative structure of microscopic, and the macroscopic behavior is defined and analyzed basing on the fundamental response of the unit cell analyzed numerically by the Displacement Discontinuity Method.
In the present paper, the theory and practice for the analysis of the stress intensity factor around the tip of joint are mainly presented and discussed, along with the the stress compensation scheme of indispensable for the analysis of the infinite structure. The case studies of a single open joint set problem are performed using a latticed model and an alternative model, and the usefulness of the SC-DDM is made clear.

抄録全体を表示

Theory and practice for the effective compliance analysis are presented and discussed, along with successful case examples, in order to make clear that the Stress Compensation-Displacement Discontinuity Method (SC-DDM) is an useful tool available for the homogenization problem of multi joint sets.
The fundamental concept of the homogenization of joint sets and the SC-DDM, proposed in the previous paper, are firstly summarized, and it is shown that an infinite structure of rock mass is homogenized using a unit cell which is a representative structure of microscopic, and that the macroscopic characteristics is able to be defined and analyzed using the fundamental response of the unit cell computed numerically by the Displacement Discontinuity Method. Subsequently the stress compensation scheme available for the analysis of the effective compliance is proposed, showing successful case studies using a latticed model and an alternative model of a single open joint set. It is shown how the restrict stress acting on the unit cell can be removed to compensate the boundary stress condition required, and how the macroscopic strain of the unit cell can be computed from the displacement distribution on the sides of a representative unit cell. Additionally, the relation between the joint density and the effective compliance is discussed, comparing with the approximation by a parallel pillar model.

抄録全体を表示

Core disking is sometimes observed in high stress region where rock stress measurements are performed by the Compact Conical-ended Borehole Overcoring (CCBO) Technique, which is one of the stress relief methods. When the tensile stress induced on the borehole bottom surface becomes larger than the tensile strength of the rock, a failure from the borehole bottom surface will be imitated. Therefore, if the stress changes on the borehole bottom surface can be analyzed during overcoring, the rock stress prior to boring may be estimated.
In this paper, assuming that the tensile stress on a borehole bottom surface induced due to overcoring is one of factors of generating core disking, the mechanism of the core disking in the CCBO is discussed as well as the location of failure initiation and the type of failure. Firstly, the characteristics of core disking in the CCBO is shown. Secondly, simulating the overcoring of the CCBO under three dimensional initial stress state in which the axis of a principal stress coincides with that of a borehole, the failure initiated on the borehole bottom surface during the overcoring is discussed, based on the results calculated by a semi-analytical boundary element process for axisymmetric elasticity with arbitrary boundary element conditions. From the results, the criterion of core disking is suggested and the applicable limitation of the CCBO is made clear. Furthermore, the X-ray CT method is applied to the recovered core with core disking, and then the state of failure within the core is visualized. Finally, it is discussed that the rock stress prior to boring is estimated by the suggested criterion of the core disking, comparing the neighboring rock stress measurement and tensile strength obtained from cores.

抄録全体を表示

CO₂ and SO₂ emissions from the copper production system in Chile were quantitatively evaluated using Life Cycle Assessment (LCA) technique. In this study, inventories such as the fuel consumption of the unit processes were based on published papers. The following observations were made based on LCI analysis:
(1) CO₂ emissions from the pyro- and hydro- metallurgical copper are about 0.88kg and 2.36 kg/kg-Cu, respectively. And, 1.9kWh and 3.0 kWh/kg-Cu were consumed for the electricity, respectively. There is much variance in the CO₂ emissions between pyro- and hydro- metallurgical copper, because sulfuric acid originated from the pyro-process is used for the leaching of hydro-process.
(2) SO₂ emissions from the pyro- and hydro- metallurgical copper are about 0.19kg and 0.23 kg/kg-Cu, respectively. The desulfurization ratio on pyro-metallurgical copper production in Chile is estimated to be 81%, which is lower than that of Japan.
(3) Pyro- and hydro-metallurgical coppers have a complementary relationship in the range of self-sufficient sulfuric acid.
The environmental burden to soil and water from the copper production system should be evaluated, because it is not covered in this study

抄録全体を表示

Magnetic separation experiments were carried out using a rare earth magnet type of magnetic roll separator and hematite, chalcopyrite and pyrite as feed material. The effects of feed sizes, their magnetic susceptibility and belt speed on the performance of the magnetic separator were investigated.
The difference in magnetic susceptibility of the three minerals was a little, however the order of their values was hematite>chalcopyrite>pyrite. Irrespective of feed size and belt speed, hematite was recovered as magnetic product, and pyrite as non-magnetic product. Chalcopyrite was collected as non-magnetic product at high belt speed or with coarse feed size, but with decreasing belt speed and feed size its collecting region was shifted to magnetic product zone. Under a suitable condition chalcopyrite concentrate with 96.4% recovery and 85.0% grade was obtained from the mixture of three minerals.
Based on the experimental results mentioned above, a mathematic model of particle movement in magnetic separation zone was derived, considering magnetic force, gravitation, centrifugal force, and frictional force and drag force. The movements under various conditions were calculated using the model, and the calculation results were in close agreement with the experimental results.

抄録全体を表示

The reduction reaction of selenate ion by TiO₂ photocatalyst in the presence of sulfate ion was studied. Sodium selenate solution was used in the experiments. The selenium concentration of this solution was 10 to 100 ppm as selenium (1.27×10^-1 to 1.27 mmol / dm³), and 1.27 to 1.27×10 mmol / dm³ of sodium sulfate and 2.5×10 mmol / dm³ of formic acid were added to it.
The rate of the reduction reaction of selenate ion by the TiO₂ photocatalyst became smaller by the presence of the sulfate ion. However, the reduction reaction of selenate ion proceeded until the remaining total selenium concentration became under 0.1 ppm. Reduced selenate ion became hydrogen selenide via amorphous selenium, and trapped by the CuSO₄ solution gas trap. On the contrary, sulfate ion was not reduced by the TiO₂ photocatalyst. The rate of the reduction reaction of selenate ion to amorphous selenium depended on the amount of adsorbed selenate ion (C_SeA) and was expressed as a dimensional function of C_SeA. The amount of adsorbed selenate ion on the TiO₂ photocatalyst was decreased with increase of the amount of sulfate ion, and was expressed as the competitive Langumuir isotherm. This is the reason why the rate of the reduction of selenate ion becomes smaller by the presence of sulfate ion.

抄録全体を表示

A selection method of an extractant and a precipitant to be effective in crystallization-stripping was investigated by using a relation between the extraction-stripping behavior of metal ions from the organic phase containing an extractant and the solubility of insoluble metal salts such as metal carbonates and metal oxalates. The uniformly mixed metal composite powders, which had a controlled particle size and shape, were produced by the crystallization-stripping of two metal ions from the organic phase. The objective product was the metal composite powders of samarium and cobalt as a magnetism material.
An extractant and a precipitant to be effective can be selected in crystallization-stripping by investigating the relation between a stripping condition of metal ions from the organic phase and the solubility of metal salts. Versatic Acid 10 and oxalic acid are a good combination in crystallization-stripping of Sm(III) and Co(II). The crystallization-stripping reaction of Sm(III) and Co(II) from Versatic Acid 10 is fast, and Sm(III) and Co(II) in the organic phase are recovered more than 96 % as metal oxalates in 5min reaction time. The recovery and particle shape of samarium-cobalt oxalates are affected by aqueous pH and agitation speed. With oxlaic acid solution at pH2 ∼ 6, Sm(III) and Co(II) in the organic phase are completely recovered as metal oxalates. Samarium-cobalt oxalate composite powders obtained at 600 rpm agitation speed are the uniformly mixed powders with the objective composition.

抄録全体を表示

種々の硫黄分圧下でシリカ飽和－鉄シリケートスラグ中に溶解している銅の存在状態が酸化物状態であるか硫化物状態であるかを明らかにするために光電子分光法を用いた分析を行った。まず，酸素と硫黄分圧を制御した雰囲気のもと1,573 K で実際の銅精鉱を製錬して得たマットとスラグについて分析した。次に， 少量の銅が溶存したシリカ飽和－鉄シリケートスラグを種々の硫黄分圧の気相と平衡させた試料をXPS で分析した。酸素と硫黄分圧は実際の銅製錬におけるものとほぼ同じになるように制御した。酸素分圧は約10^-3 Pa と一定にし，硫黄分圧を0 ～ 3.5 × 10² Pa まで変化させてスラグと平衡させた。スラグ中のCu2p_3/2 のXPS スペクトルと Cu のL₃M₄₅M₄₅オージェ電子のスペクトルを示し，その結果， スラグ中の銅は酸化態で存在していることが分かった。硫黄分圧を増大，すなわちスラグ中の硫黄濃度を増大しても対応した化学シフトは認められなかった。また，スラグ中の硫黄濃度からサルファイドキャパシティを決定した。

抄録全体を表示