ANALYTICAL STUDIES OF SOLVENT EXTRACTlON APPLIED TO VARIOUS PROCESS SOLUTIONS

A computer simulation for continuous multistage countercurrent processes extracting MgCl2 from sea water, Ti from process solution and wastes in Ti production，and gold from a thiourea leach solution, was carried out using the batch extraction and stripping data. The metal concentration in each extraction and stripping stage, the final outlet metal concentration, and the recovery are estimated by simulation under various conditions of stage number and phase ratio

FLOW CHARACTERISTICS of r-Fe203-HYDROCARBON SLURRY IN THE PRESENCE OF VARIOUS FATTY ACIDS

The effect of some fatty acids on the flocculation and dispersion properties of r-Fe203 particles in magnetic slurry was investigated. For preparation of the magnetic slurries in this experiments, r-Fe203 powders, some straight chained fatty acids with carbon numbers of C9-C21 in the alkyl chain and toluene-cyclohexane solution were used. The rheological properties of the slurry，namely the flow curve，yield stress and sedimentation volume of the r-Fe203 slurry were measured. It was found that the flow characteristics of the slurry varies depending on the alkyl chain length for each fatty acid added. The addition of stearic acid gives the best dispersion in our experimental trials. From the result of the calculation of the energy acting between particles，it was found that r-Fe203 particles in the slurry have a strongly magnetic attractive force

Studies on the Reduction of Viscosity of Highly Concentrated Metal Oxide-Water Slurries

Paint, magnetic paint, printing ink and highly concentrated slurry belong to the suspension where solid particles disperse in liquids. Rheological properties of the slurry are important in an industrial operation. Especially, it is valuable to lower the viscosity of slurry, so as to reduce the pressure drop in a slurry transport. In this paper, the apparent viscosity of highly concentrated slurry is measured and the effect of additives on theapparent viscosity is investigated using TiOo2 (rutile type), Fe203 (a type) and A1203 as dispersion particles and water as dispersion medium, respectively. The used additives are sodium hexametaphosphate, sodium oleate and polyacrylic acid. The obtained results are summurized as follows. The van der Waals\u27 attractive force and electro-static repulsive force are significantly concerned with the apparent viscosity of slurry. Sodium hexametaphosphatehas an excellent effect that it remarkably reduces the apparent viscosity of Ti02 and Fe203 slurries. Sodium oleate behaves to reduce the apparent viscosity of Fe203 slurry due to the chemisorption on the Fe203surface

Flocculation of Fine Hematite in Aqueous Solution Containing Surface-Active Agents

水溶液中の微粒子は, 界面活性物質の添加によって固体の表面疎水性や表面電荷が変えられるとき, 条件によって凝集したり分散したりする.この研究では, 酸化鉄微粒子 (α-Fe2O3) の凝集現象が, オレイン酸ソーダと1-ドデカンスルホン酸ソーダの存在下で研究されている.凝集現象を説明するために, 界面活性剤の吸着量や酸化鉄のゼータ電位が測定されている.オレイン酸は10以下のpHで酸化鉄に物理的および化学的に吸着して, 大きい負の電荷を与える.pH3以下ではその低い溶解度のために負の電荷を持った微小油滴として存在し, 酸化鉄に吸着または付着する.1-ドデカンスルホン酸ソーダは, 酸化鉄の等電点以下のpHで物理的に吸着する.酸化鉄の凝集領域がpHと界面活性剤濃度の関数として図示されている.単分子層吸着以下の吸着が生じるとき酸化鉄は凝集傾向を示し, 単分子層吸着以上の吸着では酸化鉄は分散傾向を示した.\nFine solid particles in aqueous solution are flocculated in some cases or dispersed in other cases, when surface properties such as hydrophobicity and surface charge of the solid are changed by adding surface-active agents. In the present study, flocculation phenomena of fine hematite suspension are investigated in the presence of surface active agents such as sodium oleate and sodium salt of 1-dodecane sulphonic acid. Amounts of the surfactant adsorbed on hematite and the zeta potential of hematite are measured in order to explain the flocculation phenomena.Oleic acid can be physically and chemically adsorbed on hematite in the pH region below 10 to give a large negative charge to hematite. At pH less than 3, oleic acid exists as small oil droplets with negative charge due to its low solubility. These droplets are adsorbed or adhere to hematite. On the other hand, 1-dodecane sulphonic acid is physically adsorbed on hematite, especially below the pH of the point of zero charge of hematite. The flocculation domain of hematite as a function of pH and the concentration of surfactants is illustrated in the presence of two surfactants. When adsorption of surfactants less than a mono-layer takes place, hematite particles are flocculated. When adsorption more than a mono-layer occurs, hematite particles are dispersed

Computer Simulation for Extraction Process of Gold from Thiourea Solution

A computer simulation for the continuous multistage countercurrent extraction process of gold from a thiourea leach solution was carried out by using the batch extraction and stripping data. The thiourea/hydrochloric acid/TBP system and the thiourea/sulphuric acid/TOA system were investigated for this simulation. Gold concentration in each extraction and stripping stage, and the final outlet concentration of gold and the recovery were estimated by the simulation under various conditions of stage number and phase ratio. The simulation by expressing extraction and stripping isotherms as a mathematical function and taking the function in a computer program is considered to be a superior method to estimate the extraction and stripping behaviors in each stage in a steady state. It is recognized that 8 stage extraction with the phase ratio of 5-6 and 8 stage stripping with the phase ratio of 0.3-0.4 gives 90% recovery and 15 times concentration in the case of the thiourea/hydrochloric acid/TBP system. The thiourea/sulphuric acid/TOA system is inferior to the thiourea/hydrochloric acid/TBP system in the viewpoint of the overall recovery and concentration of Au

Structure of a central stalk subunit F of prokaryotic V-type ATPase/synthase from Thermus thermophilus

The crystal structure of subunit F of vacuole-type ATPase/synthase (prokaryotic V-ATPase) was determined to of 2.2 Å resolution. The subunit reveals unexpected structural similarity to the response regulator proteins that include the Escherichia coli chemotaxis response regulator CheY. The structure was successfully placed into the low-resolution EM structure of the prokaryotic holo-V-ATPase at a location indicated by the results of crosslinking experiments. The crystal structure, together with the single-molecule analysis using fluorescence resonance energy transfer, showed that the subunit F exhibits two conformations, a ‘retracted' form in the absence and an ‘extended' form in the presence of ATP. Our results postulated that the subunit F is a regulatory subunit in the V-ATPase