Barite nucleation kinetics and the effect of additives
Fernandez-Diaz, Lurdes; Putnis, Andrew; Cumberbatch, Toby J.
European Journal of Mineralogy Volume 2 Number 4 (1990), p. 495 - 502
published: Aug 31, 1990
manuscript accepted: Feb 23, 1990
manuscript received: Oct 6, 1989
ArtNo. ESP147050204004, Price: 29.00 €
Abstract The induction period (τ) for the nucleation of barite from supersaturated solutions has been determined by measuring the intensity of the 90° light scattering from the growing precipitates. The linear dependence of log r versus (log S)-2, where S is the supersaturation, fits well to homogeneous nucleation theory with diffusion-controlled growth at [BaSO4] concentrations greater than 10-3 M. This enables the crystal-solution interfacial tension to be evaluated as 73 mJ/m2. The addition of 5 ppm of commercial polyacrylic inhibitor has a significant effect on the induction period and subsequent growth at [BaSO4] concentrations greater than 3 × 10-3 M, and increases the interfacial tension to 96 mJ/m2. The presence of NaCl has a smaller effect on the nucleation kinetics which may result from the reduction in the activity of the Ba2+ and SO42- ions. Scanning electron microscopy has been used to observe the effects on barite morphology.