マグネタイト被覆法を用いた高勾配磁選に関する基礎的研究

抄録

High gradient magnetic separation (HGMS) tests were performed after selective magnetic coating of magnetite to galena.
The results are as follows:
1) The capture rate in HGMS of quartz mixed with magnetite colloid decreased at slurry pH 9 to 11, where high potential energy barrieres calculated from DLVO theory were present. On the other hand the large capture rate of galena mixed with magnetite colloid was shown at pH 3 to 11. Therefore, the HGMS test of artificial mixture (galena 45.5%, quartz 45.5% and magnetite colloid 9%) was performed at slurry pH10. Approximately 80% grade of quartz as non-magnetics and 80% of galena as magnetics excluding magnetite were achieved at a recovery of 50% in two stages of HGMS. Subsequently, galena as a magnetics was separated effectively from magnetite by HGMS after slurry was adjusted at pH 10 and at the concentration of 1×10^-3kmol/m³ of sodium hexametaphosphate.
2) 0.5T of applied magnetic field intensity was enough to capture minerals selectively coated with magnetite by HGMS. The employment of permanent magnet is possible and the energy cost for the selective magnetic coating separation will decrease. The amount of magnetite to use in selective coating to galena was more than 50 times of that which was calculated by force balance model because of the coagulation of magnetite particles themselves.
3) The capture rate of galena mixed with magnetite did not depend on the particle size of magnetite at slurry pH 10. Especially the magnetite particles which were prepared by oxidation of ferrous hydroxide were effective to capture galena and showed strong magnetic flocculation in water because of single domain size.