Abstract: In producing a copper concentrate by flotation in which copper minerals are separated from arsenic minerals by using oxoacids of sulfur and oxidants, the arsenic in the copper concentrate is reduced by a simple method. In producing the copper concentrate by the flotation in which an arsenic-containing copper ore is a raw material, the oxoacids of sulfur and hydrogen peroxide as the oxidant are used together as additive reagents, and added in this order.

Abstract: An imaging apparatus such that residual toner on a transfer/conveyer mechanism such as a transfer belt and an intermediate transfer material is effectively removable. High-tension voltage opposite in magnetic polarity (plus) to the charged toner and a photosensitive drum is applied to a discharger 15 provided ahead of a drive member 12 for driving a transfer belt 6. The residual toner on the transfer belt 6 is removed by a brush 21, and the residual foreign substances come in contact with the photosensitive drum 1 and move onto the photosensitive drum 1 before a printing operation is started. The foreign substances are then removed by a photosensitive drum cleaner.