Levie Mweene

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Papers by Levie Mweene

Challenges and Future in Ni Laterite Ore Enrichment: A Critical Review

Mineral Processing and Extractive Metallurgy Review

Investigations into the flotation of molybdenite in the presence of chalcopyrite using (3S,4S,5S,6R)-3,4,5,6-tetrahydroxyoxane-2-carboxylate acid as a novel selective depressant: An experimental and theoretical perspective

Journal of Molecular Liquids

Selective dispersion-flocculation and flotation studies on a siliceous copper ore

Physicochemical Problems of Mineral Processing, 2018

A low-grade copper ore from Mpanda Mineral Field (MMF), Tanzania containing 0.90% Cu, 10.40% Fe a... more A low-grade copper ore from Mpanda Mineral Field (MMF), Tanzania containing 0.90% Cu, 10.40% Fe and 58.3% SiO2 was subjected to beneficiation adopting selective dispersion, flocculation and flotation techniques. Based on the mineralogical characterization of the sample chalcopyrite, pyrite and quartz were identified as the major minerals. The isoelectric point of MMF ore was observed to be at pH 2.7, signifying that the ore was highly siliceous. The addition of sodium trisilicate and xanthan gum shifted the zeta potential of ore to more electronegative values. Adsorption of xanthan gum on chalcopyrite and silica indicated that the maximum adsorption was at pH 2.3 for chalcopyrite and the adsorption isotherm exhibited L2 type of the Giles classification. On the contrary, no adsorption of xanthan gum on silica was observed. The ground ore was selectively dispersed and flocculated at pH 9.7 using 30 ppm of sodium trisilicate and 30 ppm of xanthan gum. The grade of CuFeS2 was improved t...

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Optimal pH for Heap Leaching of Low Grade Copper-Cobalt-Iron Ore

Introduction Heap leaching is a metal extraction process that is commonly used for the extraction... more Introduction Heap leaching is a metal extraction process that is commonly used for the extraction of copper, cobalt, nickel, gold, iron, silver and uranium from their low grade oxide ores using a leachant (e.g. concentrated sulphuric acid (H2SO4) (Hiskey, 1986; McMahon, 1964; ). The ore is crushed, cured, agglomerated and stacked on an impermeable pad. Raffinate from the solvent extraction dosed with concentrated sulphuric (H2SO4, 98%) acid is sprayed on the stacked ore to produce a pregnant leach solution as shown in figure 1. Concentrated sulphuric acid is used in heap leaching and its cost is the most vital economic factor (Rich, 2008). This process is preferred to other leaching processes due to; (i) its low energy requirement, (ii) absence of the tailings disposal (iii) absence of the counter-current decantation (CCD) circuits, (iv) no additional tailings impoundment, (v) suitable for treating the low grades, (v) quick installation of the needed equipments (vi) requires low cap...

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Beneficiation studies on lean grade copper ore by selective flocculation and flotation techniques

Obogashchenie Rud, 2019

Xanthan gum based investigations into the surface chemistry of cassiterite and beneficiation of cassiterite tailings

Mineral Processing and Extractive Metallurgy Review, 2020

The surface chemistry of cassiterite mineral and selective dispersion-flocculation-flotation stud... more The surface chemistry of cassiterite mineral and selective dispersion-flocculation-flotation studies on cassiterite tailings have been investigated using xanthan gum. Mineralogical studies indicate that quartz is the major mineral encapsulating cassiterite. The results of the adsorption, electrokinetic, coprecipitation, and Fourier Transform Infrared spectroscopic studies indicate that xanthan gum adsorbs on cassiterite by both physical and chemical forces. The adsorption density of xanthan gum for cassiterite decreases with an increase in pH, whereas it does not adsorb on quartz in the pH range of 3 to 12. The Gibbs free energy of adsorption for cassiterite is determined to be −35.7 kJ/mole, indicative of chemisorption. The zeta potential of cassiterite becomes more negative and its isoelectric point is shifted to more acidic pH values, attesting to specific adsorption of xanthan gum, whereas that of quartz remains unaltered, after its addition. The Fourier Transform Infrared spectroscopic investigations reveal that the adsorption of xanthan gum on cassiterite is governed by both hydrogen bonding and chemical interaction. The complexation of xanthan gum with Sn ions in the bulk solution is confirmed by dissolution and co-precipitation studies. Selective dispersion-flocculation-flotation tests on gravity tailings from Gasambya mines, Rutongo, Rwanda, demonstrate that a cleaner concentrate of 64.8% grade of Sn with 89% recovery, containing 1.9% grade of SiO 2 with 1.3% recovery could be obtained, with a selectivity index of 27.4.

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Potential Uses of Artisanal Gold Mine Tailings, with an Emphasis on the Role of Centrifugal Separation Technique

Sustainability

Few investigations have focused on the potential uses of artisanal gold (Au) mine tailings, despi... more Few investigations have focused on the potential uses of artisanal gold (Au) mine tailings, despite the fact that artisanal gold mining activity contributes to environmental issues such as greenhouse gas. Mineralogical characterizations of artisanal gold mine tailings in Miyove gold mine (Baradega and Masogwe) in Rwanda were investigated for potential utilization as a source of valuable gold, using the centrifugal separation technique. Results of X-ray diffraction analysis, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, inductively coupled plasma–optical emission spectroscopy, and X-ray fluorescence showed that artisanal gold mine tailings samples have significant amounts of gold to justify economical gold extraction opportunity. The gold grades in the ores and artisanal gold mine tailings were in the ranges of 37–152 and 2–7 g t−1, respectively. Quartz was a major phase, with minor impurities in two different types of gold ores and their respect...

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Polymer-based investigations into the surface chemistry of some sulphide minerals and the beneficiation of a low grade siliceous copper ore

Experimental study on the separation of quartz from pyrite using alginate as a selective depressant substantiated by theoretical analysis on intermolecular bonding

Separation and Purification Technology, 2021

Abstract The surface chemical properties of quartz containing iron species and pyrite in the pres... more Abstract The surface chemical properties of quartz containing iron species and pyrite in the presence of sodium alginate (ALG) as well as bulk solution studies of Fe were experimentally and theoretically investigated. The adsorption of ALG onto pyrite and quartz containing iron species was observed to decrease with increase in pH. The binding energy calculations at BP86/6-311++g/def2-TZVP level of theory indicated that the most stable structure for Si ( O H ) 5 - ∙∙∙ FeOH+∙∙∙ALG complex had a complexation energy of −834.5 kJ/mol on the singlet (S = 0) potential energy hypersurface. Additionally, FeOH+∙∙∙ALG and Si ( O H ) 5 - ∙∙∙FeOH+ complexes were the most stable on the quintet (S = 2) potential energy hypersurface with complexation energies of −2352.9 and −1596.4 kJ/mol, respectively. The nature of interaction in the complexes was further probed by using various quantum chemical tools namely quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. The results indicated that the interactions O Fe∙∙∙O in FeOH+∙∙∙ALG and Si ( O H ) 5 - ∙∙∙FeOH+ as well as O H∙∙∙O hydrogen bond in Si ( O H ) 5 - ∙∙∙FeOH+∙∙∙ALG were partially covalent in nature. In the presence of 2000 g/t of ALG at pH 5.3, the grade and recovery of Fe obtained was 44.7% and 97.2% with a selectivity index of 35.8.

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