Abstract
M.Sc.
Calcium carbonate scale formation is a major problem in industrial water and cooling systems as
well as in household systems. The resulting reduction in heat transfer and the removal of the scale
are very costly processes.
One of the methods used in the past 50 years and investigated for nearly a century, is the use of
physical fields to reduce, remove and / or inhibit scale formation. These physical fields are usually
magnetic fields, but RF electric and electrostatic fields are also used. These fields are claimed to
reduce the cost involved in the removal of scale to a minimum.
To investigate these claimed effects on scale formation, a pure calcium bicarbonate solution was
exposed to some of the commercial available units: The exposed solution was then forced to
precipitate by elevating the temperature. The pH was monitored against time, to investigate the
nucleation process of CaCO 3 and the resulting precipitate analysed for changes in crystal
morphology.
The principle conclusions made from the results were, firstly that the nucleation of CaCO 3 was
significantly delayed in one of the units tested and that the preferred morphology was changed
from the thermodynamically more stable calcite to the more unstable aragonite in that unit.
Secondly, that a direct correlation existed between the release of trace amounts of metals from
the unit and the observed effects.