Use of Seawater/Brine and Caliche’s Salts as Clean and Environmentally Friendly Sources of Chloride and Nitrate Ions for Chalcopyrite Concentrate Leaching

Abstract

A less harmful approach for the environment regarding chalcopyrite concentrate leaching, using seawater/brine and caliche’s salts as a source of chloride and nitrate ions, was investigated. Different variables were evaluated: sulfuric acid concentration, sodium nitrate concentration, chloride concentration, source of water (distilled water, seawater, and brine), temperature, concentrate sample type, nitrate source (analytical grade and industrial salt), and pre-treatment methods in order to obtain maximum copper extraction. All tests were performed at moderate temperatures (≤45 °C) and atmospheric pressure. The leaching system using distilled water, seawater, and brine base media resulted in copper extraction of 70.9%, 90.6%, and 86.6% respectively. The leaching media, with a concentration of 20 g/L Cl−, obtained a maximum Cu extraction of 93.5%. An increase in the concentration of H2SO4 and NaNO3 from 0.5 to 0.7 M, led to an increase in the copper extraction. The use of an industrial salt compared to the analytical salt did not show great variations in the percentage of extraction achieved, which would be a good and cost effective alternative. The increase in temperature from 25 to 45 °C showed a great effect on the copper leaching (of 60% until 90.6%, respectively). The pre-treatment is suggested to increase copper extraction from 60.0% to 71.4%.

Synergistic effects of ferric sulfate addition and mechanical activation on leaching of Sarcheshmeh copper sulfide concentrate

“…Because of the togetherness of chalcopyrite and pyrite in nature, a new galvanically-assisted process for chalcopyrite leaching has been introduced as the copper concentrate is leached under atmospheric pressure in the existence of pyrite in a ferric-ferrous sulfate solution [17][18][19]. Pyrite can be added as a catalyst to boost the leaching rate of Cu concentrate through forming a galvanic cell that intensifies the Cu leaching yield and rate [20].…”

Effect of Pre-Treatment with Sodium Chloride/Sulfuric Acid on the Bornite Concentrate Leaching in Chloride Medium

“…In the second stage, the Cu 3 FeS 4 product is oxidized to Cu 2+ , Fe 2+ , and elemental sulfur, which is a reaction that only occurs by leaching at high temperatures [20][21][22][23][24][25][26][27][28]. On the other hand, some papers have reported the chloride addition to copper refractory species' hydrometallurgical processing [29,30]. Copper chloride leaching from bornite concentrates and ore demonstrates that bornite was oxidized more readily in saline water (high chloride concentration); mineralogical analyses of the residues showed that the final reaction product was sulfur.…”

Development of an empirical model for copper extraction from chalcocite in chloride media

“…Chilean mining companies operate in extremely arid areas, which has considerably increased the use of seawater in mineral processing [21]. In recent years, various studies have been developed for the use of seawater in extractive metallurgy processes, either for flotation and thickening [22][23][24] and leaching [25][26][27] processes. When working in chlorinated media, the oxidative dissolution of chalcocite occurs in two stages [28,29], where the first stage is faster while the second can be accelerated with the increase in temperature [17,19,30,31].…”