Biological CO₂ fixations were assessed from an economical view point. Three methods are perspective as the countermeasure of global warming. The first is afforestation. It can store CO₂ by 200-300 ton-C/ha as organic substances in timbers and soils. The cost of CO₂ fixation is decided from the cost of plantation, being 700-1, 000 yen/ton-C in developping countries. The second is microbial CO₂ fixation using chlorella sp. The fixation products can be used as feed for livestock. The replacement of feed crop with chlorella can reduce Green House effects Gases (GHGs) emission by cutting the GHGs from crop fields during cultivation.In this case, the cost for the fixation would be free, since the fixation products are merchandise. The third is a utilization of biological pumping in the ocean to decrease atmospheric CO₂ concentration, i. e., the enhanced growths of the phvtoplanktons in the ocean and then, transfer of atmospheric CO₂ to the deep ocean. If the iron fertilization were effective for increase of some ocean productivities, the cost for CO₂ fixation would be around 100yen/ton-C.
The feasibility of biological CO₂ fixation can be assessed by the comparison of their costs with that of physical methods and political methods. The cost would be 25, 000yen/ton-C for CO₂ recovery from stack gases and its ocean dumping as a physical method. For carbon taxation to stabilize CO₂ emission increase to the level of 1988, it would cost 240, 000yen/ton-C. The biological CO₂ fixation is the most economical method among the three and therefore, the most feasible for global warming.

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The time-dependent deformation of weak rock mass around mine tunnel which had been induced by face advance was calculated by two demensional FEM model with non-linear visco-elastic characteristics. The results of simulation agreed well with the measured vertical displacements in roof and convergences of tunnel at Matsumine mine. It is showen in this simulation that if the rock mass behaves as continuous media and the appropriate mechanical parameters are chosen as input parameter, the proposed model can predict the time-dependent deformation of visco-elastic rock mass with only six input parameters within ashort calculation time.

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A series of experiments were carried out on reduction of platinum from aqueous chloroplatinic acid solution (H₂PtCl₆) with hydrogen in a gas bubbling batch reactor or an autoclave for a range of temperatures from 293K to 353K and hydrogen partial pressures from 0.025 to 0.5 MPa. On the basis of experimental results, reaction mechanism and morphorogy of the products were analyzed.
Apparent reaction rates in the main stage of the reduction showed a 0th-order dependence on the platinum concentration, while showing an induction period in the initial stage of the reduction. During the induction period, reduction of PtCl₆^2- to PtCl₄ ^2- was presumed to take place until the concentration of PtCl₄ ^2- was in equilibrium. The apparent reaction rates in the main stage (Oth-order kinetic regime) increased in proportion to hydrogen partial pressure and were independent of the additional amount of Pt seeds.The activation energy in this stage was as low as 19.0 kJ·mol^-1. Therefore it was clear that the rate determining step of the reaction was the diffusion step of dissolved hydrogen through the liquid laminar film at the gas-liquid interface.
According to SEM examination, platinum particles reduced were found to be spherical with mean diameter 1-5μm. In addition, the particles with coarse surface and smaller diameter were observed to increase as the reduction proceeded

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In order to clarify the reduction rate of zinc oxide with metallic iron under nitrogen stream, kinetic experiments were carried out in the temperature range between 1, 223 and 1, 373 K. Experimental data were an alyzed in terms of the mixed-control kinetics based on the isothermal shrinking unreacted-core model, in which activities of ZnO and FeO were taken into account. The rate parameters were then determined.
The reaction rate constant k_c and the effective diffusivity D_e are represented by the follwing equations: kc/mol·m^-2·s^-1=exp {-185.2×10³/(RT)+13.72}D_e/m²·S^-1=exp (-3433/T-8.620)
The activation energy of the reaction was 185kJ·mol^-1. The calculated reduction curves by using the rate parameters based on the shrinking unreacted-core model finely reproduced the experimental data.
At temperature of only 50K higher, the reaction rates of zinc oxide with metallic iron under nitrogen stream was comparable with that under vacuum.

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To reduce the consuming time and labor for measurement, new desorbed gas measurement devices were developed. Measurement of gas content of some coal seams in Hokkaido were carried out by using those new devices. In this paper, measurement results are described. From the results, we may conclude as followings;
1) Measurement method of desorbed gas by using new devices could reduce the time and labor consuming for measurement.
2) The coal seam of the highest gas content is the Lower Seam of Mitsubishi Minami Oyubari Coal Mine and the value is 12.9cc/g. The lowest one is Noborikawa No.1 Coal Seam of Sorachi Coal Mine and the value is 0.33cc/g.
3) Generally, the gas content increases with the depth of borehole which is drilled for sample collection. But the gas content of some samples which were collected at the depth of 20m or 25m at Mitsui Ashibetsu Coal Mine were little. The main cause for decreasing the gas content can be related to the stress distribution around the roadway.
4) The gas content of coal seam depends on geological condition of the surrounding formation where samples are collected and quality of coal.

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Hydrolysis of acidic ferric sulphate solutions of various concentrations with the addition of sodium sulphate has been investigated in an autoclave at temperatures of 185°C and 200°C.
The results obtained were as follows:
1. When the hydrolysis of ferric sulphate solutions was at equilibrium, the concentration of ferric ion increased with an increase in sulphuric acid concentrations, while at the same sulphuric acid concentration, the concentration of ferric ion decreased considerably with an increase in the addition of sodium sulphate.
2. In the absence of sodium sulphate, hydrolysis and precipitation of ferric oxide, Fe₂O₃, occurred at lower sulphuric acid concentrations, and ferric basic sulphate, Fe (OH) SO₄, was precipitated at higher concentrations of sulphuric acid, while with the addition of sodium sulphate in the ferric sulphate solutions, hydrolysis and precipitation of sodium jarosite, NaFe₃ (SO₄) ₂ (OH) ₆, occurred at higher concentrations of sulphuric acid.
3. At a temperature of 185°C, when respectively about 7.5g/l Na⁺ ion, 15g/lNa⁺ ion and 30g/l Na⁺ion as sodium sulphate were added in the ferric sulphate solutions, hydrolysis and precipitation of ferric oxide occurred up to the sulphuric acid concentration of 22.8g/l or below, 29.7g/l or below and 48.3g/l or below, while at those or above, sodium jarosite was precipitated.
4. At a temperature of 200°C, when respectively about 15g/l Na⁺ion and 30g/l Na⁺ ion as sodium sulphate were added in the ferric sulphate solutions, hydrolysis and precipitation of ferric oxide occurred up to the sulphuric acid concentration of 36.5g/l or below and 60.4g/l or below, while at those or above, sodium jarosite was precipitated.

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The reduction rate of cupric sulfate solution with hydrogen was catalytically enhanced by addition of 0.5g/l Bi³⁺. The catalytic effect of Bi³⁺was remarkable at high sulfuric acid concentration.
Without Bi³⁺ addition, the reduction curves seem to be consisted of two segment, an initial stage with faster reduction rate and a later stage with very slow rate.
After nucleation of copper, Cu₂S is begun to form on copper surface, and when copper particles are covered with Cu₂S, the reduction rate becomes very slow, and a long reaction time is required to complete the reduction.
By addition of Bi³⁺, formation of Cu₂S is supressed and also the reduction rate after nucleation is accelerated by addition of Bi³⁺.

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Reduction of silver nitrate solution with some reducing agents was studied to obtain fine silver powder suitable for conductive paste.
In ammoniacal solution, sub-micron spherical silver particles were obtained by use of hydroquinone, pyrogallol, and 3, 4-dihydroxytoluene; uene as a reducing agent. Reduction rates with the reductants were very fast and completed within a few seconds with almost 100% yields.
From the result of X-ray diffraction and the observations of internal structure by transmission electron microscope, it was considered that the spherical particles were resulted from the agglomeration of crystallittes about 20nm in size.

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Acidic cupric sulfate solution, equilibrated with copper at 220°C, was injected into the same solution which was already placed in a large stainless reservoir.
From the observation of the solution and the measurement of light transmittance through the solution, it was found that the solution was clear for a short while after injection and suddenly became turbid. The fact suggests that the homogeneous nucleation of copper take place after some induction period.
The particle numbers formed per unit volume (N) could be approximately expressed as a function of supersaturation degree (S)
N=S^2.05×10^8.7
From the observation of internal structure with TEM and SEM, it was found that copper particles were polycrystals which had radial internal structures.

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The present paper develops mechanics of disc cutter which will provide an insight into rational design of its elements such as bearing assemblies. Mechanics of disc cutter suggests that the tool force should be associated with the moment of force since the resultant tool force does not pass through the center of disc, but acts on the circular edge of disc. The experiments of disc cutting have shown that the moment of force derived in this paper is valid for circular and linear cutting modes, no matter how disc cutter plunges with an acute angle against the surface of rock. Mechanics of disc cutter also allows us to evaluate the reaction force excerted at the bearing assemblies, that is the bearing load. Illustrative calculations have shown that the bearing load increases with the plunge angle of disc cutter, but decreases with the dip angle of rock surface. The present paper, therefore, concludes that the bearing load can be controlled by the plunge angle of disc cutter relative to the surface of rock.

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Phase relations in the Ti-Fe-O ternary system and the equilibrium partial pressures of oxygen have been determined at 1, 173K by using a thermogravimetric technique in CO-CO₂ gas mixtures. The results indicate that upgrading ilmenite to rutile is basically possible and its possibility was confirmed experimentally. The standard Gibbs energy of the reactions at 1, 173K were also obtained as follows:
Fe (s) +FeTiO₃ (s) +1/2O₂ (g) =Fe₂TiO₄ (s), -197.4kJ·mol^-1,
Fe (s) +TiO₂ (s) +1/2O₂ (g) =FeTiO₃ (s), -208.6kJ·mol^-1. Both the activities of magnetite and ulvospinel in the Fe₃O₄-Fe₂TiO₄ solid solutions coexisting with metallic iron at 1, 173K show negative deviation from Raoult's law.

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The Reduction-Diffusion (R-D) process was applied to the production of Sm2Co17 type rare earth permanent magnet materials with composition Sm (Co_0.67Fe_0.22Cu_0.10Zr^0.02) _7.2. The main objective of this study was the attainment of the specified composition in the final alloy product. For this objective, copper powder was excluded from starting materials and added after the R-D reaction, zirconium was added in the form of zirconia, and an aqueous ammonium chloride solution was used to leach out the remainder of metallic calcium and calcium oxide, the latter being formed during the reduction stage of the R-D process. The following were also examined; the amount of metallic calcium as a reductant, the grain size of cobalt powder, temperature and duration of the R-D reaction, homogenization condition of the alloy after the addition of copper powder, excess amounts of samarium oxide and zirconia among the starting materials, and so forth. The magnet alloy obtained in the present study contained a small amount of calcium and a little more oxygen than that prepared simply by melting metallic raw materials. Both of them, however, showed almost the same magnetic properties when treated by the identical step aging.

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