Title:Microwave Thermal Treatment for the Recovery of Re in Copper and Molybdenum Concentrates
Volume: 11
Issue: 2
Author(s): Vanesa Bazan*, Ariel Maratta, Gastón Villafañe, Pablo Pacheco and Elena Brandaleze
Affiliation:
- CONICET, Institute of Mining Research, Universidad Nacional de San Juan, Av. Libertador General San Martin 1109,
Oeste, San Juan, Argentina
Keywords:
Copper ores, molybdenum ores, microwave heat treatment, rhenium, coal mining, OM.
Abstract:
Background: Rhenium (Re) is obtained as a by-product during the extraction of copper
and molybdenum ores. In current extractive metallurgy, Re extraction involves a heat treatment that
causes Re losses by volatilization and release of toxic gases into the environment.
Objective: This research proposes a novel microwave heat treatment (MWHT) to enhance Re extraction
avoiding Re losses and toxic gas release into the environment.
Methods: A novel MWHT and traditional thermal processes used in mining were applied to Cu-
Mo concentrates. The elemental composition analysis of the concentrate was performed by atomic
spectrometry. The crystalline phase was identified by X-ray diffraction. Particle structure observations
were performed with an optical microscopy (OM) and scanning electron microscopy (SEM)
with a Field Emission, including semiquantitative analysis (EDS). Thermal behavior and non-isothermal
reduction processes were studied using Thermogravimetry Differential Thermal Analysis
(TG-DTA).
Results: Re, S and As release decreased 5% during MWHT, compared to 34% of traditional methods.
Molybdenite (MoS2) and Chalcopyrite (CuFeS2) were the crystalline phases in the ore after
MWHT. Rhenium was found as an oxide (ReO3) and metallic Re. Samples under MWHT showed
structural transformations in the mineral particles, with minimal mass losses and high Re and Mo
concentrations. The structural transformation of the ore involved microcracks formation.
Conclusion: The MWHT induces a combination of particle degradation mechanisms and lower
temperature requirements that prevent Re losses. Lower gas emissions turn this technology into an
environmentally friendly one. Crystalline transformation of the Re-chalcopyrite phase enhances
Re release during leaching, the next step after MWHT in the hydrometallurgical extraction.