Pyrite removal from several clays by high gradient magnetic separation (HGMS) method was investigated. Effects of magnetic susceptibility (MS) values of pyrite and clays, and operation conditions on the pyrite removal were studied. Following results are discussed.
(1) MS values of pyrite in the Itaya clay A and Sendatsu clay C were 1.01×10-6 emu/g and 0.64×10-6 emu/g, respectively. In spite of their low SM values, pyrite particles could be separated from clays by HGMS method because of their large particle size.
(2) Efficiency of pyrite removal from clays were mainly dependent on the MS values of origin clays, and the good results were naturally obtained for low value clays. Pyrite removal from Itaya clay D (MS =0.08×10-6 emu/g), Itaya clay A (MS =0.63×10-6emu/g) and Sendatsu clay C (MS =1.91×10-6emu/g) was examined under the following condition ; matrix : FW, magnetic field strength : 14.5 kG and linear velocity : 38.4 m/hr. The XRD peak intensities of pyrite (200) in the N-mag clays were 0 cps, 10 cps and 45 cps for Itaya clay D, Itaya clay A and Sendatsu clay C, and their Fe2O3 content were 0.34 wt.%, 0.54 wt.% and 1.92 wt.% respectively.
(3) Good results for pyrite removal from Itaya clay A by HGMS method were obtained at the high magnetic field strength (9.7-14.5 kG) and rather low linear velocity (22.1-38.4 m/hr). The matrix FW was best suitable for the pyrite removal.
(4) By treating of Itaya clay A at 14.5 kG and 22.1 m/hr with matrix FW, whiteness increased from 80.5 to 87.4 with decreasing Fe2O3 content from 1.46 wt.% to 0.38 wt.%, and N-mag clay yield was 89.00.
(5) Also titanium oxide was easily removed from clays under the HGMS conditions which pyrite removal from clays resulted in good success.
