Solid–Liquid Equilibrium and Copper Sulfate Crystallization Process Design from a Sulfuric-Acid–Seawater System in the Temperature Range from 293.15 to 333.15 K

Abstract

The objective of this work is to determine experimentally the solubilities and the water activities for aqueous solutions of copper sulfate in seawater at different temperatures and to use this information to represent the solid–liquid equilibrium of a copper-sulfate–sulfuric-acid–seawater system. In a previous work, the experimental solubility data of copper sulfate in acidic seawater from 293.15 to 318.15 K were obtained experimentally; in this study, these data were complemented by measuring solubilities at 323.15 and 333.15 K. The thermodynamic representation of the phase equilibrium is based on a simple methodology reported in the literature with some modifications, where the Pitzer model and a Born-type equation were used for modeling the copper sulfate and sulfuric acid effects, respectively, and the seawater was considered as a solvent. The amounts of copper sulfate precipitated and the optimum yield as a function of the sulfuric acid concentration were estimated, giving relevant information for the drowning-out crystallization process design of copper sulfate using seawater.