Chlorine flow in Japan in 1995 was surveyed from the viewpoint of industrial metabolism using a substance flow analysis method. About 3,543 kt / year of chlorine mainly manufactured by electrodialysis of imported salt is converted to various chlorinated substances and consumed. Finally they are emitted as chlorinated organics, salt, ionic solution or polymers into the environment. The industrial metabolism structure of chlorine shows dendritic flow representing mainly raw-product chain relation in chemical reaction. Recycling flows in the metabolism structure can be found in hydrochloric acid , solvent , flon and PVC. Especially the PVC flow diagram has been analized through the usage of PVC. It has been concluded 1,000 kt / year of PVC is accumulated in Japan.

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The author elaborated the results of studies on Surface Subsidence in various coal fileds in Japan(Kushiro), England(NCB collieries) and Republic of South Africa (Sigma). Firstly, the author analysed the sphere at goaf area where fallen rock debris solidified at bottom part while upper rock strata deteriorated by cracking caused by earth pressure. And it was found that the vertical wise extent of the sphere was as same as face length mined. It was also found that the maximum subsidence occured within the sphere showed similar trend to those theories of Area Complete Exraction developed by Lehman et al.
Secondly, surface subsidence was largely affected by (k_i) which indicated breaking factor of fallen rock debris, and which was built in the author's Subsidence Formulae. In case, if representative rock strata in the sphere had large value of Young's Modulus, and if it was homogeneous and thick, surface subsidence was given small ratio, and took longer period for its termination. Under such circumstances, k_i was found to be small. On the contrary, if characteristics of rock strata was quite the reverse, subsidence ratio was large, terminating period was short and k_i was turned to large value.
It was particularly noted that in case of the second extraction of lower coal seam after 2 years in time of completion of upper coal seam extraction, drastic change of ratio and termination period was observed. And in this case, breaking factor (k_i) was turned to large value despite that k_i of in-situ solid state rock strata was very small.
Hence, the author predicted that the Subsidence Formulae developed by the author can be widely utilized to detect surface subsidence phenomena in various coal fields in various coal producing countries.

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The disposal of carbon dioxide to the marine and sea bed sediments as CO₂ gas hydrate is an innovative technique for solving the global environment issue. Experiments on the formation and dissociation of gas hydrate have been carried out using a pressure vessel to investigate the effect of carbon dioxide concentration in the gas phase. From the experiment results, the following are clarified:
1 There is a strong relationship between the partial pressure of carbon dioxide concentration and the temperature of formation and dissociation of gas hydrate. Therefore, the use of this relation enables the estimation of equilibrium conditions of mixture gas.
2 The initial formation speed varies from 0.1 to 0.5 ml / (min. g). Considering, the average values of the initial formation speed, the initial formation speed increases as the carbon dioxide concentration of the initial mixture gas also increases.
3 From the analysis of component gas of gas hydrate and space gas, it can be assumed that nitrogen and oxygen are also incorporated into the cage of hydrate structure as guest molecules. Moreover, it can be seen that the carbon dioxide concentration in the initial space gas is of higher level than the carbon dioxide concentration in the space gas at the time when the gas hydrate grew up. Therefore, this hydrate technology applies in the concentration of carbon dioxide.
In the near future, we will attempt to carry out tests on the formation and dissociation of CO₂ hydrate under a low concentration of CO₂. Furthermore, we will analyze the structure of gas hydrate using the Raman spectroscopy to clarify that nitrogen and oxygen are incorporated into the cage of gas hydrate structure as guest molecules.

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Viscosity changes of hectorite slurry and drilling mud water under hydrothermal condition were observed by using stirring autoclave coupled with torque meter. Semi-quantitative values of viscosity were estimated on the basis of an empirical liner function between share rate and torque of a standard fluid.
Viscosity of the drilling mud water changed slightly in the range from room temperature to 220 °C, suggesting moderate characteristics for high temperature mud water. But its viscosity depleted suddenly above 220 °C, which indicates that two phase separation was occured due to alteration of the mud water. Viscosity of the hectorite slurry increased in the ranging from 120 °C to 180 °C, which corresponds to the crystallization temperature of hectorite. However, its viscosity decreased above 180 °C after crystallization of hectorite. These facts indicate that two phase separation, composing from crystallized hectorite and residual solution, was occurred in the temperature range up to 180°C.
Hectorite slurry is one of possible agents for plugging fractures in geothermal reservoir to prevent lost circulation. The equipment developed here and estimation method of viscosity are applicable to evaluate plugging process of hectorite slurry in a geothermal reservoir.

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A new and simple technique was developed in this study to evaluate the kinetic parameters of the crystal growth stage during the precipitation of radial aluminium trihydroxide. Pure radial particles were grown by cooling Bayer liquors according to a precisely controlled temperature profile. This allows good control of the supersaturation of the solution to suppress nucleation and agglomeration, and allows predominantly crystal growth. As continuous cooling is required, the determination of the activation energy and rate constant based on conventional constant temperature experiments is not applicable. A new technique is therefore required to determine the rate constant and activation energy of crystal growth. By dividing the cooling curve into discrete intervals, an average temperature is assigned to each interval so that the average kinetic parameters within each can be determined. The Arrhenius plots of the rate constants against 1 / T yield activation energy of 300±20 kJ.mol ^-1 and the growth rate constants varying from 2.3 ~ 8.1 × 10 ^-5 μm·h ^-1·g ^-2·l² within temperature range 81 ~ 88 °C.

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The experimental collision frequency factors of monodispersed polystyrene latex (PSL) particles in KCl solutions were measured by the use of the dynamic light scattering method. This method determines the cluster-size distribution by counting the number of different clusters during the coagulation process and therefore permits the determination of the rough collision frequency factors by the fitting curves for the data. The fitting curves were calculated on the assumption that the coagulation between two same-fold particles is dominant.
Numerous studies have revealed significant discrepancies between the theoretical collision frequency factors that can be calculated from Smoluchowski and Fuchs formulation and the experimental results, especially in the slow coagulation region. In this paper's results, good qualitative agreement was found for the theoretical collision factors in the rapid coagulation, but in the slow coagulation, significant discrepancies were confirmed both qualitatively and quantitatively, especially for high-fold particles.

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This paper describes an inhibition of oxidation and growth of Thiobacillus ferrooxidans by chloride ion and the effect of diatomaceous earth against its inhibition.
Ferrous ion oxidation experiment in the absence of nutrient salts was carried out with various amount of chloride ion. The assay solution of this experiment contained only ferrous sulfate and magnesium sulfate (pH 1.5), and no bacteria grew in this condition. The oxidation of ferrous ion was inhibited by the chloride ion, and was subjected to the competitive inhibition from the Lineweaver-Burg plot. The addition of the diatomaceous earth in assay solution had no effect on the bacterial oxidation.
The growth of T. ferrooxidans in 9 K medium was also inhibited by the chloride ion. The growth kinetics of this bacterium in the presence of chloride ion were described with the modified Monod type equation including the term of inhibitor concentration. The growth inhibition reduced by the addition of diatomaceous earth in the medium. The oxidation rate in the presence of diatomaceous earth was much faster than that in the absence of it in high concentration of chloride ion. The growth inhibition constant of adsorbed bacteria was about 60 % larger than that of free bacteria, which was the reason the oxidation of ferrous ion in the presence of diatomaceous earth was faster.
The adsorption amount of T. ferrooxidans onto the diatomaceous earth was almost constant in this experimental range of the chloride ion.

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Leaching of molybdenum concentrate in NaCl aqueous solutions by electro-oxidation has been investigated, and the major process parameters, such as current density, temperature, and pulp density (nominal content of the concentrate in slurry) have been experimentally examined. The leaching rate of the concentrate was found to be proportional to current density, while the molybdenum concentration in the leach solution increased linearly with time. These results show that the concentrate was effectively oxidized by oxidizers produced by electrolysis of the NaCl solution, then dissolved rapidly into the solution. Increase in pulp density results in preferential oxidation of iron and copper in the concentrate, and it reduces the efficiency of molybdenum extraction. With the purpose of examining the feasibility of molybdenum recovery through solubility change, the pH dependence of molybdenum solubility in 10 mass% NaCl solution was investigated at various temperatures between 298 and 353 K. The solubility of molybdenum was found to be lower than 0.05 mol/l in the range of pH from 2 to 3, and increased with increasing temperature and pH of the solution. Precipitation experiments from leach solution were then examined by changing pH of the solution, and solid MoO₃·(H₂O)_x crystals, free of sulfur, were obtained from the leach solution containing large amount of SO₄^2-. Trace rhenium in the concentrate was found dissolve into the leach solution and co-precipitate with molybdenum during this process.

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Lead titanium sulfide, PbTiS₃, was synthesized at relatively low temperatures of 300 ~ 450 °C by the reaction of PbS (or Pb) and TiS₂ in a large excess amount of sulfur melt in sealed ampoules for several days. The addition of 10 mole % PbCl₂ was found to effect significantly the yield of PbTiS₃. This effect was smaller when 10 mole % PbI₂ was added. The accompanying impurities were PbS, TiS₃, TiS₂, TiO₂, PbCl₂ after the excess sulfur was removed by filtration in a molten state. The amounts of such impurities were greatly decreased by the combination of the addition of PbCl₂ and the lowering of the initial PbS amount, and PbTiS₃ was synthesized in nearly pure form.

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Electrodeposition of copper, indium and their alloy on titanium substrate from the solution containing citric acid were studied where the effects of copper and citric acid concentrations on the alloy deposition behavior were examined. The polarization curve for either copper or indium shows that, when citric acid is added to the solution, the metal deposition potential becomes less noble and the limiting current density decreases. In the alloy depositon, with the decrease in the copper concentration, the indium deposition potential becomes less noble and the limiting current density decreases. The deposition condition of the stoichiometric alloy, CuIn, depends on the citric acid and copper concentrations as well as the current density.
Calculation of ionic equilibria in the solution shows that the formation of CuCit ^- ion decreases Cu ion concentration and its limiting current density, which explains the experimental result.

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