The removing techniques for oil spill in the marine environment are summarized from a viewpoint of physical and chemical principle in this review. The recovery systems and the enhancement of biodegradation are recommended to remove oil spill in offshore area under the stormy weather, because there are left rooms to estimate the effect of chemical agents and dispersions on the marin environment. The recommended recovery systems are the suction pump to remove the weathered oil-water emulsions and oil debris, and the techniques to remove oil leaked from the tankers sinking in the deep sea. Large-scale ships are also recommended to be constructed for removing a large scale of oil spill under the stormy marine environment.

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X-ray Computed Tomography (CT) is utilized to measure the permeability of rock and to visualize the migration of fluid fronts. The X-ray CT makes it possible to evaluate the attenuation of X-ray at each point within rock, by digitizing shadow pictures taken from various directions and subsequent image reconstruction, and the subtraction of CT images provides successfully the time-dependent distribution of the water ratio within rock. A percolation experiment using a disc specimen is proposed to measure the coefficient of permeability. Apparatus, operation procedure and necessary data processing are described along with the theory for interpreting the experimental results. Thus, it is stated how the coefficient of permeability is determined by means of the X-ray CT. The proposed measurement is supported by case study.

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In this paper, two-phase flows of oil and water were considered numerically. For a description of a sharp interface between oil and water, the original VOF method was modified by means of an inclined line-segment in a numerical cell. Continuous and separated core-annular flows (CAF) in a two-dimensional channel were simulated by the modified VOF method in combination with a κ-ε turbulent model. Some of main results are as follows : 1) In comparison with the original VOF method, the modified method gave satisfactory conservation of mass and shape to the Zalesak's problem. 2) The modified method is applicable to a complex flow in which merging and separation of fluid lumps occur. 3) Time averaged pressure gradients of continuos core- annular flows were slightly higher than those of water flows in both the simulation and experiments. 4) Pressure gradients of separated core flows fluctuated largely due to distortion of the core; however, time averaged pressure gradients of them were close to those of the continuous CAF.

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The dissolution of iron oxides is an important hydrometallurgical process if it can be applied to industry. Some of the potential applications include cleaning of iron surface and removal of iron oxide from industrial minerals. In this study, the dissolution of hematite obtained from iron ores using oxalic acid was evaluated at different initial pHs, acid concentration and temperature. It was found that the dissolution of iron oxide rust was very slow at temperatures ranging from 25°C to 60°C, but increased rapidly as temperature became above 90°C. An increase in concentration of oxalic acid in the range of 0.048～0.476mol/l increased the dissolution rate, whereas the pH caused some passivation (at pH > 2.5) after improving the rate from pH 1 to pH 2.5. When the technique was applied to dissolving of the iron oxide rust, it was found that the iron oxides existing in the rust, which are mainly goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and iron hydroxide (Fe(OH)₃) can be dissolved faster than with hematite.

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Calcium hydroxide was used to remove ferric ions from waste iron (III) oxalato complexes in solution which were generated from the chemical leaching of clay minerals with oxalic acid, other industrial processes. In this study, the iron (III) oxalato complex solution which was prepared with iron (III) chloride and oxalic acid, was studied on various factors such as temperature, oxalic acid concentration, initial pH and amount of calcium hydroxide. The pH of the solution depended on the concentration of calcium hydroxide. More than 0.054mol/l of calcium hydroxide was needed for the treatment of 0.010mol/l of Fe dissolved in 0.100mol/l of oxalic acid at 25°C. Fe(OH)₃ was formed from the iron (III) oxalato complex by Ca(OH)₂, and this reaction was completed within 15 minutes. The concentration of calcium hydroxide added was dependant upon the initial pH and Fe concentration in the oxalic acid solution. When the precipitated sludge was reused repeatedly two or more times, the efficiency decreased sharply due to the inert nature of CaC₂O₄・H₂O and a small amount of Ca(OH)₂. The reaction temperature did not play an important role on the removal of iron from the ferric oxalato complex solution, but the temperature was effective in removing Fe (III) and Al (III) from the clay leaching solution by adjusting the pH to alkaline range using calcium hydroxide.

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Removal efficiencies of Pb and Cd from artificially contaminated clay soils with chelating agents such as ethylenediaminetetraacetic acid (EDTA) have been investigated. Retention characteristics of Pb in bentonite and kaolinite are dependent on pH. At high pH, precipitation mechanisms (e.g., precipitating as hydroxide/oxide or carbonate) dominate. As pH decreases, exchangeable form becomes dominant. The amounts of Pb retained in bentonite increase up to pH 5, but conversely decrease thereafter. This result corresponds to the change of the forms of Pb retained in bentonite. The amounts of Pb retained in kaolinite increase with an increase in pH. Removal efficiency of Pb retained as hydroxide/oxide or carbonate with chelating agents increases with an increase in pH of leach liquor. Pb retained as exchangeable form is removed by reaction with chelating agents and cation exchange with H⁺. Meanwhile, retention characteristics of Cd in bentonite and kaolinite are not dependent on pH and exchangeable form is dominant. The amounts of Cd retained in bentonite increase up to pH 5 and remain nearly constant thereafter. Meanwhile, the amounts of Cd retained in kaolinite increase with an increase in pH. Removal efficiency of Cd retained as exchangeable form increases with an increase in acidity of leach liquor. Also, removal efficiencies of Pb and Cd retained as exchangeable forms are enhanced by addition of Na salts.

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To obtain the vapor pressure data of PbO in the PbO base slags with the high content of PbO, a transpiration method using a vertical volatilization chamber was developed and the vapor pressures were determined at 1, 423 and 1, 473 K for liquid PbO-FeO_1.5-CaO-SiO₂ and PbO-ZnO-FeO_1.5-CaO-SiO₂ slags nearly corresponding to those in the oxidation zone of the QSL lead smelting furnace. For any slag investigated, the activity of PbO was found to present a negative deviation from the Raoultian behavior and the activity coefficient of PbO showed a minimum value at the mole fraction of PbO in the slag with about 0.5. It was found that the acitivity coefficient of PbO increased with increasing Q of the slag, defined by Q = mass % CaO/(mass % SiO₂ + mass % CaO). It was also clarified that the activity coefficient of PbO in the slag with ZnO was smaller than that in the slag without ZnO. The observed behaviors were explained qualitatively on the basis of the chemical affinity between PbO and other components in the slag. The partial pressures of various lead components in the gas phase were evaluated using the obtained thermodynamic data and it was suggested that the elemental lead species was predominant in the gas phase corresponding to the oxidation zone of the QSL furnace where the metallic lead phase coexists with the slag phase.

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The present refining of copper from sulfide copper ores by pyrometallurgical process is lack for the environmental concerns, that is, generation of harmful SO₂ gas and high energy consumption. Considering our environmental aspect and saving the energy, we directed our attention to recover Cu by using the more advantageous L-SX=EW (Leaching-Solvent Extraction-Electrowinning) method. This hydrometallurgical L-SX-EW method can be designed as a closed system and lessen the wastes from the process. Based on the investigation we have already reported with respect to the extraction mechanism of Cu²⁺ with EHO (2-ethylhexanal oxime), in this study the separation of Cu²⁺ was examined from the leached solution obtained after leaching copper sulfide ores with ferric chloride solution, and the realizability of the environmentally friendly hydrometallurgical process was also investigated. The extractant EHO is very effective to separate Cu²⁺ from the leached solution containing Fe²⁺, Fe³⁺ and Zn²⁺. Cupric ions are selectively extracted in the organic phase at chloride ion concentration, 3～5 mol/dm³, while Fe³⁺ and Zn²⁺ are not transferred into the organic phase. The stages and phase ratio (A/O) required to attain the desired Cu²⁺ recovery are estimated to be 2-stage countercurrent extraction with the phase ratio (A/O) of 1.5. In order to strip Cu with water from the organic phase, 6-stages countercurrent stripping with the phase ratio (O/A) of 1.8 are required. By the extraction and stripping operation, 10 g/dm³Cu²⁺ is purified and concentrated to 25 g/dm³ Cu²⁺.

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A high current density operation is desired to improve the productivity in copper electrorefining. It is known that an agitation of the electrolyte has a potential to overcome the problems such as the passivation of anode and dendritic deposition at cathode in the high current density operation. In this paper, effects of the fluid motion on the behaviors of arsenic, antimony and bismuth were investigated under high current density conditions. The concentrations of impurities in the deposition increased with increasing the current density without the forced convection. An increase in the fluid velocity suppressed the increase in impurity concentrations. The impurity concentrations were high especially in the initial stage of the deposition without the forced convection. It corresponded to the decrease in the cathode potential measured in the period. It means that the enrichment of impurities was induced electrochemically. The reason of the decrease in the cathode potential was low concentration of the copper ion on the electrode surface due to the consumption of the ion with the electrolysis. The forced convection of the electrolyte enhanced the ionic mass tranfer and thus suppressed the polarization and deposition of the impurities. It was made clear that the fluid motion is effective for the achievement of the electrolysis under the high current density.

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The solubility of porous silica-gel into water is one of serious problems for application of porous silica-gel for catalyst and other sophisticated usage. In particular, the surface area is so large that active surface of silica-gel quickly reacts with water and the basic structure destroys by dissolving silica and oxygen which compose the porous materials. However, the quantitative studies of solubility in hot water as well as cold water have been seldom found in this field because the dissolution phenomena is very complicated. In the first place, the method to measure the solubility in hot water was designed in this study and the condition, at 180 °C, 1hr. was fixed to evaluate the solubility. The effect of co-exist elements on the solubility into hot water has been widely surveyed. There are three groups where the solubility changes were observed and the several elements which were considered to react with silica showed the excellent results to reduce the solubility. Aluminum is one of the best co-exist element. Al-modified silica-gel had small solubility although the surface area of porous silica-gel did not decrease. NMR measurements showed that the surface chemical structure of aluminum replaced silica-gel changed and especially OH moiety decreased remarkably.

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