Characterization of copper slag for beneficiation of iron and copper

Abstract

Before disposal of any metallurgical waste to the environment, it is the responsibility of mining institutes to adhere to the permissible metal content limits. Base metals, especially iron and copper, have adverse effects of reducing the soil pH and excessive concentrations of these in the disposed waste may result in soil pollution and toxicity, with adverse effects on plant growth and animal health. Copper slag is a metallurgical waste that is disposed by way of stockpiling at designated dump sites within a mining site. The observed depletion of highgrade iron ores in Botswana and the environmental hazards associated with disposal of untreated metallurgical waste, presents an opportunity for research on secondary sources of iron and copper. Our characterization results show that this BCL copper slag is a good secondary source of base metals, especially iron and copper. These results reveal that the elemental proportion of iron was around 35.4%. Literature states that an iron grade that is considered viable for economic beneficiation should be at least 25% and this slag has an iron content above this limit, hence poses a serious environmental threat upon disposal. This article presents an investigation into the mineralogy of the copper slag at a plant situated in Selebi Phikwe, a town in the northern part of Botswana. Quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) quantified that no cobaltsulphide was detected and strongly indicated that the cobalt within the sample occurs in solid solution in either the fayalite phase or glass phase. Spot analysis from electron probe microanalyzer (EPMS) images indicated an unusually high content of copper compared to any other metal. We elucidate that, this was due to the inefficient processing techniques employed during operational years of the mine. The relative compositions of Co, Fe, Ni and Cu were 0.14%, 35.4%, 0.28% and 0.29% respectively. This analysis justifies our interest in considering this copper slag as a secondary source of iron for beneficiation purposes.

Effect of Grinding Media Size on Ferronickel Slag Ball Milling Efficiency and Energy Requirements Using Kinetics and Attainable Region Approaches

“…Four series of grinding tests were conducted using a laboratory batch scale ball mill (Version, Sepor, Los Angeles, CA, USA) that operated at 66 rpm (1.1 Hz) corresponding to 70% of its critical speed, under dry conditions, as seen in Table 2. The grinding media consisted of balls with various sizes and density 7.85 g/cm 3 , corresponding to ball filling volume J = 20%, while the material filling volume f c was 4%. Consequently, the interstitial void space of the balls U that is filled with slag was kept constant at 50%, as shown in Equation (7).…”

“…where S w is the specific surface area, ρ p is the particle density, D [3,2] is the mean surface area (Sauter mean diameter), and f, k are the surface and volume coefficients (for spheres f /k = 6).…”

“…At present, large volumes of slags containing toxic elements, such as chromium, lead, and cadmium, are disposed of on land or underwater and cause serious contamination of water resources and soil [2]. However, slags have found a wide range of applications in the construction, cement, and fertilizers industries, and can be considered as secondary sources for base metals, especially iron and copper [3]. Previous studies indicate that certain metals can be effectively extracted from slags using hydro-and pyro-metallurgical processes, as well as several beneficiation techniques [4][5][6][7].…”

Corrosion Resistance of MgO and Cr2O3-Based Refractory Raw Materials to PbO-Rich Cu Slag Determined by Hot-Stage Microscopy and Pellet Corrosion Test

“…As During high-temperature process, the oxide components of the slag form low melting phases as a result of chemical reactions, e.g., fayalite Fe 2 [SiO 4 ] (T M = 1205 • C) [8,9], cuprite Cu 2 O (T M = 1215 • C) [10], magnetite Fe 3 O 4 (T M = 1539 • C) [11], and lead silicate Pb 2 SiO 4 (T M = 747 • C) [7]. Therefore, since the 1950s, the most suitable refractories for Cu production have been magnesia-chromite refractories produced from chromite ore and sintered or fused magnesia.…”

Environmental and Socioeconomic Impact of Copper Slag—A Review

“…In previous studies, the initial characterization of smelter slag was followed by the proposal of a process route to utilize the slag. The slag can be characterized using Xray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS), and light optical microscopy (LOM) in transmitted and reflected light [45][46][47]. Previous studies have indicated that copper slag behaves differently when subjected to different temperatures, thus exhibiting different properties [42,48].…”