Metal-Selective Processing from the Los Sulfatos Porphyry-Type Deposit in Chile: Co, Au, and Re Recovery Workflows Based on Advanced Geochemical Characterization

Abstract

Sulfides extracted from porphyry-type deposits can contain a number of metals critical for the global energy transition, e.g., Co and precious metals such as Au and Re. These metals are currently determined on composite mineral samples, which commonly results in their dilution. Thus, it is possible that some metals of interest are overlooked during metallurgical processing and are subsequently lost to tailings. Here, an advanced geochemical characterization is implemented directly on metal-bearing sulfides, determining the grade of each targeted trace metal and recognizing its specific host mineral. Results show that pyrite is a prime host mineral for Co (up to 24,000 ppm) and commonly contains Au (up to 5 ppm), while molybdenite contains high grades of Re (up to 514 ppm) and Au (up to 31 ppm). Both minerals represent around 0.2% of the mineralized samples. The dataset is used to evaluate the possibility of extracting trace metals as by-products during Cu-sulfide processing, by the addition of unit operations to conventional plant designs. A remarkable advantage of the proposed workflows is that costs of mining, crushing, and grinding stages are accounted for in the copper production investments. The proposed geochemical characterization can be applied to other porphyry-type operations to improve the metallic benefits from a single deposit.

Enhanced elemental and mineralogical imaging of Cu-mineralized rocks by coupling μ-LIBS and HSI

“…Furthermore, dilution of some important trace metals to concentrations below the detection limits can result in the loose of crucial information to the mining planning. 8 Conventional techniques for mineralogical characterization for powder samples can include the use of X-ray diffraction (XRD) and X-ray uorescence (XRF); for polished thin sections electron probe micro-analysis (EPMA), automated electron microscopy (QEMSCAN) applied on polished thin sections. In recent years, more sophisticated techniques for micro-chemical characterization of minerals, such as Raman spectroscopy (RAMAN) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), 8,9 have been applied to evaluate metal content and economic potential of mineral deposits.…”

“…8 Conventional techniques for mineralogical characterization for powder samples can include the use of X-ray diffraction (XRD) and X-ray uorescence (XRF); for polished thin sections electron probe micro-analysis (EPMA), automated electron microscopy (QEMSCAN) applied on polished thin sections. In recent years, more sophisticated techniques for micro-chemical characterization of minerals, such as Raman spectroscopy (RAMAN) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), 8,9 have been applied to evaluate metal content and economic potential of mineral deposits. However, all those techniques still have some important limitations, e.g., time-consuming, limited to a small surface of scanning, and relatively costly, triggering constraints for their massive implementation in the mining lab facilities.…”

Editorial for Special Issue “Critical Metals in Hydrothermal Ores: Resources, Recovery, and Challenges”

“…One describes the development of technological innovations that allow for the extraction of critical and precious metals associated with low-grade porphyry ores (e.g., Co, Te, Au, Ag) [17]. Velásquez et al [17] use the world-class porphyry Los Sulfatos deposit, located in the Chilean Central Andes, as a case study, and performed in situ and high-resolution geochemical characterisation of the metal-bearing sulphides by LA-ICPMS, the knowledge of which is informative for selective metal treatment. The second study demonstrates extraction of copper from lead and silver mine waste dumps by using a simple, robust, and versatile leaching process [18].…”