Growth rates of gibbsite single crystals determined using in situ optical microscopy

Although the crystallization of gibbsite via the Bayer process is an establ ished industry, the mechanism by which gibbsite crystallizes is not well un derstood. In the microscopic investigation of gibbsite crystal growth, the phenomenon of growth rate dispersion was observed. The study of the growth rate dependence on supersaturation showed that growth of the prismatic face s is occurring via a spiral growth mechanism. In the case of the basal face , above a relative supersaturation of 0.67, birth and spread is the princip al mechanism operating, while spiral growth is the major mechanism operatin g below a relative supersaturation of 0.67. (C) 1999 Elsevier Science B.V. All rights reserved.