Pourbaix diagrams for copper ores processing with seawater
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Universidad de Antofagasta
Universidad Catolica del Norte
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Luis A Cisternas   

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Publication date: 2020-06-03
Physicochem. Probl. Miner. Process. 2020;56(4):625–640
Decreases in the copper grade, waste disposal, energy supply, and water scarcity are some of the most critical challenges for the copper mining industries. One of the alternatives to counteract the water scarcity is the use of seawater, whether raw, partially desalinated, or desalinated. The use of seawater implies the generation of several compounds as a result of the interaction of ions in waters and ores. For this reason, it is required a greater understanding of these compounds generated on mineral processing, being Pourbaix diagrams used to estimate the possible compounds that will be formed in an aqueous medium for a given metal ore. In this paper, the effect of temperature, salinity, and Cu-concentration on the stability of the copper-solid species was investigated by constructing Pourbaix diagrams for different copper ore types with seawater. The results show that the corrosion areas decrease when the temperature increases for both oxidized and sulfide minerals. It was confirmed that the concentration is a critical variable that influences the size of corrosion areas. In terms of the effect of the other ions that seawater contains, carbonate, chloride, and bromide affect the stability of the Cu-solid species. The proposed diagrams serve as a useful tool to predict the stable species that may be obtained when seawater is used. The use of seawater in mining is an essential issue because it is considered as a more sustainable alternative instead of use freshwater or desalinated seawater, especially in locations with complex water availability, as is northern Chile.