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

本课题包括两类研究工作。一是研制了从10 nm到1微米小距离的导电镀金半球与镀金板在溶剂中的电场和磁场相互作用力测试仪。当硅油在半球和平板之间施加电场时，在硅油分子长度约50 nm附近，在小于0.5微米的距离内，周期性地观察到粘着和排斥的振荡。电流变流体在硅油中分散蒙脱石时，在电场作用下，其作用力在0.1um左右出现振荡，表现为二次凝聚直径。磁力作用于大脑半球和平板周围。以有机硅基磁流体为溶剂，研究了颗粒间的凝聚和分散作用。进行了超细粒锡石的载体浮选和细粒黑钨矿的磁选试验。在油酸钠捕收剂体系中，以粗粒锡石和其他粗粒矿物如锡石、方铅矿和石英为捕收剂，对锡石颗粒(-5微米)进行了浮选研究。细颗粒回收率由50%提高到95%。以粗磁铁矿为载体，油酸钠为表面活性剂，采用高梯度磁选机对黑钨矿颗粒(-5um)进行了研究。0.27T载流磁选使细粒黑钨矿回收率由50%提高到90%。

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.