Effect of Seawater on the Solubility and Physicochemical Properties of Acidic Copper Sulfate Solutions

Abstract

Seawater is an alternative to freshwater, which is scarce for copper mining in northern Chile, but it has components that may be problematic for hydrometallurgical processes. This work determines the influence of seawater on the solid−liquid equilibrium for acid solutions of CuSO 4 at different temperatures, (298.15 to 323.15) K, and its effect on physical properties (density, refractive index, ionic conductivity, and viscosity). The measured properties show an average difference between CuSO 4 in seawater and CuSO 4 in freshwater of 1.42 % for solubility, 1 % for density, 0.29 % for refractive index, 24.61 % for ionic conductivity, and 5.61 % for viscosity. In addition, the physical properties of unsaturated solutions composed of CuSO 4 in acidic seawater at different temperatures, (298.15 to 323.15) K, and molalities, (0.1 to 1.8) m, were measured. The experimental data for the physical properties were correlated using Othmer's rule. This equation yields a good fit and predicts saturation data with the exception of ionic conductivity, where the Casteel−Amis equation is recommended. The solubilities and properties for both systems (acidic seawater and freshwater) are similar. This observation suggests that seawater may be appropriate for leaching with no major short-term effects.

Solubilities and Physical Properties of Saturated Solutions in the Copper Sulfate + Sulfuric Acid + Seawater System at Different Temperatures

“…Also, the figure shows that viscosity levels decrease slightly with increasing temperature. This behavior is expected, as observed in the work of Hernández, Hotlos and Price (Hotlos and Jaskula, 1988;Price and Davenport, 1980;Hernández et al, 2012). These results confirmed the good fit between experimental values for concentrations of the salt and the physical properties of the saturated solutions at four temperature levels, in a broad range of acid concentrations.…”

“…The experiments were performed using filtered natural seawater obtained from San Jorge Bay, Antofagasta, Chile. Table 1 shows the composition of the seawater, obtained by chemical analysis, used in this work (Hernández et al, 2012). …”

“…In a mining process, the solid−liquid equilibrium and physical properties of solutions change upon seawater incorporation, especially the density and viscosity; which are used in pipe-sizing and pumping calculations. These properties are related to the cost of energy required to bring seawater to mining operations, usually farther than 120 km (Hernández et al, 2012). Copper sulfate pentahydrate (Blue vitriol) is a copper salt with a wide range of commercial applications: in agriculture as a pesticide, fungicide, feed, and soil additive (Milligan and Moyer, 1975); in mining, it is used as a floatation reagent in recovery of zinc and lead (De Juan et al, 1999); as a blue and green pigment in dyes, as a print toner in photography, in the production of other copper compounds, and in leather tanning (Richardson, 1997).…”

“…In order to optimize the water use, it is interesting to investigate the influence of seawater on the copper sulfate crystallization process. In the literature, there is a publication available of the behavior of copper sulfate in a seawater system (Hernández et al, 2012); this paper provides solubilities and physical properties data of CuSO 4 in seawater at pH 2. The present work studies the effect of seawater (3.5% salinity) on the solid-liquid equilibrium of copper sulfate in acid solutions at different temperatures (from 293.15 K to 318.15 K).…”

Remoción de Calcio y Magnesio en Agua de Mar para Mejorar la Concentración de Sólidos en la Descarga de Espesadores

“…Si bien la implementación directa de agua de mar en la industria minera involucra numerosos desafíos operacionales, la necesidad de enfrentar los problemas de escasez de agua genera que en muchas zonas sea la única opción viable para conservar la sustentabilidad de este sector productivo (Cisternas y Gálvez, 2018;Hernández et al, 2012;Ordóñez et al, 2013). Las distancias y altitudes geográficas a las que se debe transportar el agua desde la costa hasta donde se ubican los yacimientos suelen ser considerablemente altas, involucrando costos de bombeo significativos.…”