Abstract
The processing of Cu, Co, and Zn at the Boleo project in Mexico involves two-stage (oxidation–reduction) leaching to extract a total of 85–88% Cu in 4 h. The first stage is an oxidation leaching using sulphuric acid (120 kg/tonne ore) at an Eh of 900 mV for 2 h. Then, the reduction stage takes place in 2 h with SO2 gas sparging for Mn and Co extraction at an Eh of 350–370 mV. The final extraction rates of metal values are 92% of Mn, 80% of Co, and 60% of Co, respectively, after 4 h of leaching at 70 °C. However, the same metal recoveries were obtained within 2 h using an equal amount of sulphuric acid and the addition of 25 kg of SO2 per tonne of ore in a single stage leaching in this research. In this case, the Fe extracted from the ore as Fe2+/Fe3+ is believed to have acted as an electrochemical couple contiguously leaching the Cu sulphide and Mn oxides, which also increased the Cu recovery as the Cu mineralised mostly intergrowths in these mineral structure matrices. A significant improvement was made in which the leaching time was halved to 2 h compared to 4 h in the previous plant design and current operation, involving the two-stage oxidation–reduction leaching.
Highlights
The Boleo project is one of the world’s largest hydrometallurgical plants processing complex oxide ores, and is located in the middle of Baja California Sur, Mexico
Samples collected at different time intervals during the leaching experiment were analysed using inductively coupled plasma optical emission spectroscopy (ICP-OES) from
The leaching operation at the Boleo process is currently conducted through two stages, with the addition of 100–120 kg sulphuric acid/tonne ore
Summary
The Boleo project is one of the world’s largest hydrometallurgical plants processing complex oxide ores, and is located in the middle of Baja California Sur, Mexico. The project is operated by the Mexican company Minera y Metalurúgica del Boleo S.A. de C.V. The Boleo deposit, containing coppercobalt–zinc–manganese, is a historic open-pit copper mine that mainly excavated the high-grade sulphide ore, starting in the 1860s, for over 70 years and has recently been redeveloped by MMB following an extensive test work [2]. The process developed involves two-stage oxidation–reduction leaching, followed by several stages of solvent extraction to recover Cu, Co, and Zn. The multi-stages of the solvent extraction were based on conventional copper solvent extraction and electrowinning [3], and the patented DSX®
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