IMPROVING PROCESS SAFETY AND EFFICIENCY BY UNDERSTANDING FOAM FORMATION AND CONTROL

Formation of foam in Bayer process liquors and slurries can severely impact process efficiency in a number of ways. In addition, stable foam that forms in tanks also presents a number of significant safety hazards to plant personnel and can provide a ready site for precipitation of scale and unwanted contaminants. As a result, appropriate mitigation and control of foam formation and stabilization are critically important in ensuring safe and efficient plant operation. Foam formation and control is also vitally important in many other industries, including those using froth flotation processes. While the desired outcome in such operations may be generation rather than mitigation of foam, a large amount of work has now been completed that increases the fundamental understanding of conditions required for bubble formation, stabilization and breakage.

This fundamental understanding has now been used in Bayer applications to enhance foam control methods and develop more effective means to improve process efficiency and safety. The general principles and most recent advances in fundamental understanding related to bubble formation and stabilization are presented together with a review of effective control methods. The impact and mechanism of engineering solutions as well as antifoam and defoamer chemistries are considered. Alternative strategies and application methods for foam control are proposed and new test methods to assess and benchmark the efficacy and operation of such strategies are presented.