Computer-aided formulation of silica defoamers for the paper industry

In the manufacture of paper, wood chips are ‘cooked’ in a vat of chemicals that has a tendency to boil over, much like spaghetti cooked in a pot of water. An important use of precipited silica, fine particle silicon dioxide (a noncrystalline form of sand), is in eliminating such foams from industrial processes. To be effective, the silica must be dispersed, often in a mixture of mineral oil and other chemicals. Based on an empirical equation of the defoamer’s performance as well as on a deterministic equation of ingredient cost, the author developed a nonlinear programming model for optimal performance. Paper manufacturers confirmed the validity of the predicted optimal formula in four out of five paper plant trials.