Gypsum Scale Inhibition on Process Equipment Surfaces: A Review

The aim of the paper is to quantify and to compare the antiscalant effect of several additives on gypsum precipitation by measuring the retard on the induction period for nucleation. Through a well-assessed laser light scattering technique previously devised, the induction times are measured, and then used to estimate thermodynamic parameters such as the activation energy for nucleation, in a calcium sulfate supersaturated solution with the addition of NTMP, PBTC and citric acid. Experiments are carried out at a fixed additive concentration level (equal to 0.05 g/L), with the temperature varying in the range 15 – 35 °C. A comparison among different additives allows to define which is the most active in retarding gypsum scale formation.