Interaction force measurement under electric and magnetic field at small distance and carrier separation with coagulation and dispersion

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This topic includes two kinds of research works. One is the development of measurement instrument of interaction force under electric field and magnetic field between conductive gold coated hemisphere and plate in solvent at small distances from 10 nm to 1mum. When applying electric field in silicone oil between hemisphere and plate, the oscillation of adhesion and repulsion was observed periodically at near the silicone oil molecule length of about 50 nm within less than 0.5 mum distance. On the other hand the interaction force of ER fluid dispersing smectite in silicone oil under electric field showed oscillation at the period of about 0.1 mum that shows a secondary coagulation diameter. The magnetic force was applied with the surrounding the hemisphere and plate. The silicone of based magnetic fluidis used as the solvent.The other research is the utilization of coagulation and dispersion between particles. The carrier flotation of ultrafine cassiterite and magnetic separation of fine wolframite were carried out. The cassiterite particle (-5mum) was investigated using coarse cassiterite and the other kinds of coarse minerals, such as cerussite, galena and quartz as canier in a sodium oleate collector system in the flotation. The fine particles recovery increased from 50% to 95%. Also the wolframite particle (-5mum) was investigated using coarse magnetite as carriers and sodium oleate as the surfactant by high gradient magnetic separator. The fine wolframite recovery improved from 50% to 90% by carrier magnetic separation at 0.27T.