<Original Papers>Ore Dressing Investigations of Titaniferous Iron Placer.(II) : The Application of High-intensity Magnetic Separation and the Fundamental Consideratio on Grinding

The titaniferous iron placer from Sabishiro-daira, Aomori Prefecture was used as a sample. The sample was analyzed 23.60% Fe, and 5.14% TiO_2. A Wetherill-type separator and a batch ball mill were used in the tests. The size distribution of the ground sample obeyed the Schuhmann equation and the degree of grinding, G, was expressed by the following equation : G=-100n/ek^2,where e is the base of Napierian logarithm, k the size modulus in μ, and n the size exponent in the Schuhmann equation. The grinding index expressed as the ratio of G corresponding to any degree of grinding to G_0 of the initial feed was found to be in a linear relation with the time, t, of grinding. Hence, the grindability number, R, of the sample under the specified conditions of grinding was defined by the following equation : R=1/(d(G/G_0)/dt). In the magnetic separation tests, the concentrate analyzing 60.3% Fe and 13.6% TiO_2 was obtained at the field strength of 350 oersteds and that analyzing 22.2% Fe and 14.8% TiO_2 at the strength between 7,900 and 9,000 oersteds. The titanium concentrate may be obtained by removing the gangue minerals from the latter either by the gravity separation or by the electrostatic separation. The maximum recoveries of 71.4% Fe and 94.3% TiO_2 were obtained at the field strength of 12,800 oersteds. It was found that the degree of grinding of the feed to the magnetic separator should be kept within reasonable limits. The effect of scavenging magnetic tailings was examined