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J. Y. Hwang Vo1. 1, No. 2 136 Figure 4 shows the relations between the dosage of MR-1 and magnetic enhancement on quartz. A linear increase of magnetic susceptibility with the increase of magnetic reagent dosage was again observed in the range of investigation. At a dosage equivalent to 0.01g magnetite per gram of quartz, magnetic susceptibility was increased from 0.44 x 10-6cgs/g to 221 x 10-6cgs/g. Figure 4. Magnetic enhancement of quartz at various MR-1 dosages. Nonionic surfactant have rarely been utilized in mineral flotation. However, many nonionic surfactants can be adsorbed on minerals through hydrogen bonding [8], a polyoxyethylene type surfactant is a typical example. MR-45 is a nonionic magnetic reagent employing polyoxyethylene-4 lauryl ether as the outer layer surfactant. The adsorption of this magnetic reagent on quartz, calcite, kaolinite, and pyrite is shown on Figure 5. Quartz showed strong adsorption of this reagent at pH up to 7. Hydrogen bonding is believed to be the reason. At higher pH, quartz may have strong negative surface charge and begin to repel the magnetic reagent through the electrokinetic force. Pyrite showed a similar trend of adsorption that may be explained by the same reason. Calcite maintained strong adsorption from pH 3 to 11 because this mineral does not develop strong negative surface charges at these pH levels. Kaolinite showed a similar trend of adsorption as calcite does. Although kaolinite may carry a stronger negative surface charge than calcite, the high surface area of kaolinite and the van der Waals force may have assisted the adsorption at high pH.