Washing the fibers from foams for higher yields in flotation deinking

The purpose of this work was to evaluate the possibility of washing pulp fibers from a flotation froth. A steadystate froth column was created in which the formation of foam balanced the collapse of foam. Dilute pulp and wash water were sprayed on the top of the froth, and measurements were mode of the concentration of fibers that broke through into the liquid area below the froth. The results showed that it is possible to increase pulp yield in deinking flotation by washing the froth. A minimum wash water flux is required to keep fibers out of the froth. A mechanism is proposed to explain how fibers are washed from relatively dry froths. Application: This work shows the conditions under which fibers and fines can be washed from foams. This information can be used to design flotation deinking cells which will give higher yield while giving good ink removal.