Modeling and simulation of separation process in flotation system

In order to design a flotation circuit to remove ink and contaminants from slushed old corrugated container (OCC) pulp suspension, a model based on mass balance was developed. The model is a five fractional model, which handles mass flow rate of ink, fiber, fines, filler and dichloromethane (DCM) extractives. A detailed method of calculating the deinking selectivity of a material from experimental data, described in terms of reject ratio, is presented. Three flotation deinking systems were simulated. In a single stage flotation system, increasing the number of flotation cells improved cleanness of the accept pulp suspension while it decreased yield at the same time. Yield can be increased by adding a second stage and by introducing the accept flow of the second stage into the feed flow of the first stage. However, the cleanness of the accept pulp was deteriorated. It was shown that yield can be increased without compensating the cleanness of the accept pulp by utilizing the accept pulp from the second stage for another paper machine line instead of sending back to the feed flow of the first stage.