1971 Volume 24 Issue 5 Pages 183-189
Alkaline scale (calcium carbonate and magnesium hydroxide) and calcium sulfate scale are formed the evaporation process of sea water. Among these substances, the following reaction takesace: CaCO2(S) +MgSO4(L)+H2O (L) Mg (OH)2(S)+CaSO4(L)+CO2(G).
The calcium carbonate scale is deposited by the decomposition of the calcium bicarbonate solution, nd this rate is proportional to the concentration of calcium and to the square of the bicarbonate oncentration.
The magnesium hydroxide scale is formed by the above reaction toward the right side at highmperature, and this rate is proportional to the concentration of magnesium but is in inverseoportion to that of calcium.The calcium carbonate is crystallized by the above reaction toward the left side at the roommperature, where normal magnesium carbonate MgCO3·3H2O can be used instead of magnesiumydroxide and carbon dioxide. When normal carbonate is added to sea water, the reaction towarde left side takes place, and calcium component is removed as calcium carbonate precipitate.urthermore, the precipitation rate is influenced by the impurity of the additive. In this case, theddition of calcium carbonate as seed crystal indicates a positive effect in the following order: lcium carbonate monohydrate>aragonite>calcite.
