Enhanced copper recovery from Chingola refractory ore

The Chingola Refractory Ore (CRO), in Zambia’s Copperbelt province, represents a significant copper resource, with more than 150 million tonnes in stockpiles since the 1950s. CRO contains 0.99 wt.% Cu, primarily in the form of cupriferous micas, with lesser amounts of copper found in malachite, pseudomalachite and chrysocolla. This ore was previously not processed due to the difficulty of recovering copper, which is structurally integrated in the mica lattice. Following a literature review, high-intensity magnetic separation, direct, staged flotation, and ultrasonic enhanced leaching were identified as underexplored options for the recovery of copper. These techniques are promising due to the paramagnetic properties of most Cu-bearing minerals, the propensity of some Cu-bearing minerals to be made hydrophobic, and the enhanced leaching kinetics due to ultrasonic energy. Wet high-intensity magnetic separation (WHIMS) testwork achieved a maximum recovery of 83 wt.% Cu at a grade of 1.7 wt.% Cu in the concentrate. It was found that larger particle size, higher slurry density, and greater magnetic field strength improved copper recovery and mass pull, while a higher feed rate had a negative effect. A two-stage flotation process was developed, consisting of non-refractory oxide flotation followed by refractory mica flotation. The optimum flotation result was 76.3 wt.% Cu recovery at 1.5 wt.% Cu grade. Collector dosage was the most critical factor affecting both the recovery and the grade of refractory Cu and the recovery of non-refractory Cu. In contrast, the pH was the most significant variable affecting the grade of non-refractory Cu. Depressant dosage using sodium silicate had little effect. Leaching at high temperature (65 °C) and with ultrasonication improved Cu recovery, leading to recovery of over 95% Cu, while leaching at 45 °C yielded comparable rates to ultrasonic-assisted leaching. Modelling the mechanics of dissolution suggests that the leaching rate is initially limited by chemical reaction at the ore particle surface. Over time, the leaching rate becomes increasingly controlled by diffusion. An economic analysis indicates that WHIMS is more efficient than flotation, while high-temperature leaching at 65 °C is more effective than ultrasonic-assisted leaching. Integrating WHIMS with high-temperature leaching is recommended as the most effective economic option for processing CRO.<p></p>

Author dc:creator

• Michael Kapembwa (21042230)

• copper
• magnetic separation
• flotation
• leaching
• refractory ore

Statement dc:rights

• All rights reserved
• Open Access after 2027-08-16

Identifier

10779/exe.31310509.v1

OAI identifier oai:identifier

oai:figshare.com:article/31310509