Leaching saturation lines

If the common ion is calcium, then the reaction is described by a vertical arrow pointing upward in Fig. 6.7(d) (line A-B). With further dissolution of gypsum and Ca increases, groundwater composition then moves upward along the calcite saturation curve (line B-C) in Fig. 6.7(d) to higher CO2 pressures. Point C will correspond to saturation with respect to gypsum, if the mineral is not completely leached from the rock. 

FIGURE 11.3. The steady-state profile of soil salinity, expressed as the electrical conductivity of the saturation extract, in lysimeters. The irrigation water has EC values of 2 (solid lines) and 4 (dashed lines) dS m "1. Numbers on the figure are the respective leaching fractions. 

KCI in a NaCI-saturated solution that still increases with temperature, NaCI shows retrograde solubility in KCI-saturated solutions (lines 3 and 4). This particular solubility behavior is used in the so-called hot leaching process to separate KCI and NaCI from sylvinite crude salts. It is obvious from the solubility curves that cooling a solution saturated with both salts (point of intersection of lines 3 and 4 at about 100 "C) leads to selective crystallization of KCI as target compound. (Reproduced with permission from Ref [8].)... 

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