Abstract
An alternative copper concentrate leaching process using sodium nitrate and sulfuric acid diluted in seawater followed by gas scrubbing to recover the sodium nitrate has been evaluated. The work involved leaching test carried out under various condition by varying temperature, leaching time, particle size, and concentrations of NaNO3 and H2SO4. The amount of copper extracted from the chalcopyrite concentrate leached with seawater, 0.5 M of H2SO4 and 0.5 M of NaNO3 increased from 78% at room temperature to 91% at 45 °C in 96 h and 46 h of leaching, respectively. Gas scrubbing with the alkaline solution of NaOH was explored to recover part of the sodium nitrate. The dissolved salts were recovered by evaporation as sodium nitrate and sodium nitrite crystals.
Highlights
Chilean mining is facing a shortage of water resources, depletion of copper oxide ores and those containing secondary sulfide copper
This paper proposes a feasible process to leach chalcopyrite concentrate with a mixture of sodium nitrate and diluted sulfuric acid dissolved in seawater as a source of chloride ions at atmospheric pressure and moderate temperature (≤45 ◦ C)
Nitrite-nitrate salts were characterized by differential scanning calorimetry using a Mettler Toledo TGA/Differential scanning calorimetry (DSC) 1 StarSystem, (NETZSCH, Bavaria, Germany)
Summary
Chilean mining is facing a shortage of water resources, depletion of copper oxide ores and those containing secondary sulfide copper. This depletion will leave chalcopyrite ores as the main source of copper for future plants. The extractive metallurgy of chalcopyrite is based largely on a traditional route involving comminution and flotation, smelting and electrorefining, representing around the 85% of the copper production in Chile [2]. The main problem for treating chalcopyrite by a hydrometallurgy route is its refractoriness This refractoriness is due to the formation of a passivating layer on the surface of chalcopyrite that inhibits the contact of mineral with oxidizing agents, reducing the dissolution rate. It is well known that the dissolution of chalcopyrite is a potential-dependent reaction and many studies have been carried out to elucidate the relationship between the solution potential and this passivating layer [2,3]
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