Characterization of barite suspensions during synthesis by light scattering

Barite concentration changes were made by stepwise addition of barium dichl oride to a disodium sulfate solution with intermediate temperature scans wh ile light scattering was measured continuously. Comparing with independent particle size determinations, recorded turbidity changes corresponded well to changes in particle concentration and size. In the absence of dispersing agents, light scattering from stirred BaSO4 suspensions at temperatures > 50 degreesC varied in a random fashion, indicating loosely associated parti cle aggregates. With a dispersant an almost linear relationship between par ticle concentration and light scattering was established in a wide temperat ure range. A nonionic surfactant of the alkyl ethoxylate type and a polyacr yl amide were compared with respect to their capacity to stabilize BaSO4 su spension turbidities. Correlations observed between particle size and light scattering of the suspension vs temperature and the relative light scatter ing stabilizing mechanism of dispersants are discussed. It is inferred that essentially monodisperse barite particles may be produced by precipitation in water in the presence of a suitable dispersant. Despite the complexity of the system it was possible, with the new analytical technique, to observ e that the nonionic dispersant tested did not significantly affect barite c rystal growth, but the polyacryl amide was found to have a pronounced effec t on the concentration at which particle formation is first observed as wel l as on particle size. (C) 2001 Academic Press.