In this paper the research results on the preparation of ferri-magnetofluids through colloid chemical methods developed in China are in-troduced , and the applications of the resulted fluids in mineral separations are...In this paper the research results on the preparation of ferri-magnetofluids through colloid chemical methods developed in China are in-troduced , and the applications of the resulted fluids in mineral separations are described. The colloid chemical method includes the procedure of oxi-dation-hydrolysis-collection-dispersion. It is shown that by adding NaOH to an FeSO4 ?7H2O aqueous solution, followed by aeration, an oxidation-hydrolysis reaction occurs which produces ultrafine Fe3O4 particles. The particles may then be collected by sodium oleate into kerosene phase and thus forming stable oil-base ferrimagnetofluid, or, alternately, the parti-cles may be coated with sodium oleate first, then flocculated by adding HC1, follmved by redispersion in water by adding sodium dodecyl benzen-sulphonate, to form a water-base ferrimagnetofluid. The above ferrimag-netofluids have been used as separation media in the separation of arsenopy-rite from galena, and in the separation of gold from hard- rock gold ores. The results show that the ferrimagnetofluids are better than paramag-netofluids.展开更多
A novel direct measurement strategy of bottom velocities and shear stresses based on the use of ferrofluids is presented. Such a strategy overcomes some of the limits of state-of-the-art instruments. A preliminary exp...A novel direct measurement strategy of bottom velocities and shear stresses based on the use of ferrofluids is presented. Such a strategy overcomes some of the limits of state-of-the-art instruments. A preliminary experimental campaign has been carried out in the presence of currents in steady flow conditions in order to test the effects of ferrofluid quantity and of the controlling permanent magnetic force. An alternating current （AC） circuit and a direct current （DC） conditioning circuit have been tested. For velocities larger than 0.05 m/s, the near-bottom velocity-output voltage calibration curve has a monotone parabolic shape. The sensitivity of the instrument is increased by a factor of 30 when the DC circuit is used.展开更多
文摘In this paper the research results on the preparation of ferri-magnetofluids through colloid chemical methods developed in China are in-troduced , and the applications of the resulted fluids in mineral separations are described. The colloid chemical method includes the procedure of oxi-dation-hydrolysis-collection-dispersion. It is shown that by adding NaOH to an FeSO4 ?7H2O aqueous solution, followed by aeration, an oxidation-hydrolysis reaction occurs which produces ultrafine Fe3O4 particles. The particles may then be collected by sodium oleate into kerosene phase and thus forming stable oil-base ferrimagnetofluid, or, alternately, the parti-cles may be coated with sodium oleate first, then flocculated by adding HC1, follmved by redispersion in water by adding sodium dodecyl benzen-sulphonate, to form a water-base ferrimagnetofluid. The above ferrimag-netofluids have been used as separation media in the separation of arsenopy-rite from galena, and in the separation of gold from hard- rock gold ores. The results show that the ferrimagnetofluids are better than paramag-netofluids.
基金funded by the EC project HYDRALAB IV (Contract No. 261520)by the PRIN 2010-2011 project HYDROCARby the PON 2007-2013 project SEAPORT funded by MIUR (Italy)
文摘A novel direct measurement strategy of bottom velocities and shear stresses based on the use of ferrofluids is presented. Such a strategy overcomes some of the limits of state-of-the-art instruments. A preliminary experimental campaign has been carried out in the presence of currents in steady flow conditions in order to test the effects of ferrofluid quantity and of the controlling permanent magnetic force. An alternating current （AC） circuit and a direct current （DC） conditioning circuit have been tested. For velocities larger than 0.05 m/s, the near-bottom velocity-output voltage calibration curve has a monotone parabolic shape. The sensitivity of the instrument is increased by a factor of 30 when the DC circuit is used.
