The simultaneous precipitation of calcium carbonate and magnesium hydroxide in the water softening process

Reactive crystallization of calcium carbonate by gas‐liquid and liquid‐liquid reactions

“…Many studies of crystallization kinetics, that is. of nucleation and growth rates, by liquid-liquid (L-L) reaction have been made in continuous mixed suspension mixed product removal (CMSMPR) crystallizers, but they were performed mainly for the lime ash soda water softening process (Peters et al, 1981, Peters and Stevens, 1982, Schierholz and Stevens, 1975, Swinney et al, 1982. Few studies have been made on crystallization by gas-liquid (G-L) reaction in which solid particlcs are formed by gas absorption with chemical reaction, because of their complex reaction mechanisms.…”

“…The present work deals with the crystallization of calcium carbonate, a well-known sparingly soluble salts, by G-L and L-L reactions. The crystallization kinetics of calcium carbonate by G-L and L-L reactions has been described by the following power law model (Peters et al, 1981, Peters and Stevens. 1982, Schierholz and Stevens, 1975, Swinney et al, 1982, but their ranges of suspension density were rather narrow: It is known that there are some differences in the crystal sizes of calcium carbonate obtained by G-L and L-L reactions, but the effect of the reaction mechanism on the crystallization kinetics has not been investigated.…”