Reclamation of iron and copper from BCL slag in Botswana

T S Gabasiane; G Danha; T Mashifana; T Mamvura

doi:10.1016/j.heliyon.2024.e26614

Reclamation of iron and copper from BCL slag in Botswana

Heliyon. 2024 Feb 18;10(4):e26614. doi: 10.1016/j.heliyon.2024.e26614. eCollection 2024 Feb 29.

Authors

T S Gabasiane^{1

2}, G Danha^{1

2}, T Mashifana², T Mamvura^{1

2}

Affiliations

¹ Department of Chemical, Materials & Metallurgical Engineering, Faculty of Engineering and Technology, Botswana International University of Science and Technology, Plot 10071, Boseja Ward, Private Bag 16, Botswana.
² University of Johannesburg, Department of Chemical Engineering, School of Mining and Chemical Engineering, P O Box 17011, Doornfontein 2088, South Africa.

Abstract

High-grade copper ores have been depleted over the years, making it a challenge in the mining industry. This investigation focused on a methodology to recover iron (Fe) and copper (Cu) from a copper/nickel slag obtained from the Bamangwato Concession Limited (BCL) mine in Botswana. In this modified flotation approach, the Response Surface Methodology (RSM) was used in conjunction with the Central Composite Design (CCD) and Analysis of Variance (ANOVA) to obtain the best optimal flotation conditions for the recovery of iron and copper. Using the RSM - CCD methodology, the optimal predicted responses were illustrated by a coefficient of determination R² = 0. 9839 for recovery for Fe and 0.9655 for recovery for Cu. The recovery of copper increased with the increasing dosage of Na₂S and collector dosage, while the increase of pH, had a decrease in recovery of copper due to the decline in the stability of the froth, which led to the resistance to form stable bubbles for efficient recovery of copper. Selective flotation of copper and iron was achieved by varying the Na₂S dosage to achieve maximum recovery. Under these flotation conditions of PAX (800 g/t), pH (8), -75 μm, sulfurizing agent (Na₂S, 1000 g/t), flotation time of 8 min, pH regulator of NaOH and $H_{2} {S O}_{4}$ and Methyl Isobutyl Carbinol (MIBC) from the experimental runs merited a grade upgrade of Cu in froth concentrate from 0.581 mass% to 0.884 mass%. An enrichment ratio of 2 was realised, with the recovery of Cu being 62%, whereas Fe in the froth concentrate increased from 69.8 mass% to 71.8 mass%. The main aim was to upgrade the grade and recovery of copper and iron to enhance the recovery for copper and iron in the next experimental stage of leaching.

Keywords: Copper slag; DoE; Froth flotation; Iron and copper beneficiation; RSM.