The technique of froth flotation, as practiced in the separation of mineral ores, has been applied to the separation of carbon black from the deinking waste of the paper industry.
On the theory that carbon black (from ink) has a positive charge in water, and clay and cellulose fibers have negative charges in water, experiments were of two types. First, it was attempted to float the carbon from the clay and cellulose fibers. Second, it was attempted to float the clay and cellulose fibers from the carbon.
Several possible formulas were found for separating carbon black from deinking waste. Favorable results were obtained in both types of experiments
