The formation of iron carbonate films, or by converting carbonate to magnetite at higher
temperatures, are important means used to control the rate of corrosion in the oil and gas industry. The
FeCO3 film can slow the corrosion process by covering up the steel surface and preventing the
diffusion of corrosive species to the pipe surface. On the other hand, the excessive build up of iron
carbonate salt in the oilfield production line can be a major issue, particularly, in the absence of
effective inhibitors. The growth and thickness of the film depend upon the kinetics of precipitation and
crystal growth of iron carbonate. In such kinetic studies, it is important to keep these parameters
constant. This work was intended to study the kinetics of crystal growth of mixed calcium-ferrous
carbonate salts at constant experimental conditions. In this study all the parameters are well controlled.
A special experimental design is used to keep the initial concentrations, pH (7.1), temperature (31 and
48oC), pressure (1 atm), and ionic strength (0.5 M) constant during the course of the experiment. The
composition of calcium-ferrous carbonate salt that formed was determined. The mass flux of crystal
growth was also investigated and found to be constant.
Key words: siderite, iron carbonate, calcium carbonate, constant composition, kinetics