Hydrodynamics and Mass Transfer during the Solution Growth of the K2(Co,Ni)(SO4)2•6H2O Mixed Crystals in the Shapers

Abstract

Mathematical models of the hydrodynamics and mass transfer processes during the mixed crystal growth from low-temperature aqueous solutions have been analyzed. The features of these processes are caused by complex design of the crystallizer with a shaper. Two models of the solution flowing into the shaper have been considered. In the first model, the solution is fed to the central part of the crystal. The second model presents a peripheral solution supply along the shaper perimeter, which allows us to create a swirling flow. The calculation models correspond to laminar and turbulent regimes of solution flow during the growth of K2(Co,Ni)(SO4)2•6H2O mixed crystal from an aqueous solution.

The Influence of Supercooling and Hydrodynamics on the Mosaic and Radial Inhomogeneity of K2NiXCo(1–X)(SO4)2·6H2O Mixed Crystal

“…The thickness of this layer strongly depends on the value of the horizontal component of the flow velocity. Therefore, the greatest variations in the composition are According to the results of numerical simulation [13], the peripheral supply of the solution to the shaper with a curling of the flow provides the more uniform radial distribution of the components, compared to the supply to the center of the crystal. Moreover, in accordance with the simulation data, an increase in the flow velocity from 10 cm/s to 55 cm/s results in a significantly more uniform distribution of Ni in case of the peripheral supply of the solution.…”

“…The radial inhomogeneity of mixed crystals is associated with the nonuniformity of the solution flow near the growing face [5,12,13]. Theoretical calculations carried out to simulate the growth process of mixed crystals in the shaper have showed that the distribution of isomorphic components in the solution at the crystallization front (and hence the value of radial inhomogeneity) is determined by the flow velocity of solution and the way in which it is fed into the shaper [13].…”