RAPID ONSET OF CALCIUM-CARBONATE CRYSTALLIZATION UNDER THE INFLUENCE OF A MAGNETIC-FIELD

Although the mechanisms are not fully understood, magnetic treatment o f water systems has been in existence for over a century. One of the m ajor applications is to suppress water-scale deposition on the inner s urface of boilers, heat exchangers and pipelines. Three dynamic rates play important roles in the crystallization process: these are associa tion, dissociation and nucleation rates. In this paper we report on a series of laboratory experiments concerning the formation of calcium c arbonate from super-saturated solution. The results indicate that unde r certain conditions in the presence of an external magnetic field, th e nucleation rate can be greatly increased. This was observed as a rap id onset or ''burst'' of crystallization within the bulk solution, and can be quantitatively described as the scattering of incident light-t he so-called Tyndall effect. As a consequence of the faster precipitat ion in the presence of the magnetic field, the resultant crystals are greater in number, with smaller sizes and irregular shapes. This obser vation is in agreement with an earlier report on a different magnetic treatment method. Copyright (C) 1996 Published by Elsevier Science Ltd .