Kirsten Corin
@uct.ac.za
Associate Professor , Centre for Minerals Research
University of Cape Town
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Malibongwe S. Manono, Saahil F. Khan, Lisa L. October, and Kirsten C. Corin
Elsevier BV
Kirsten C. Corin, David Franciolus, Jordi Boireu, and Joris Vermunt
Elsevier BV
Kirsten C. Corin, Apollonia Charamba, and Malibongwe S. Manono
Elsevier BV
Mengyan Tang, Yuangan Chen, Bo Feng, and Kirsten Claire Corin
Elsevier BV
Rešoketšwe M. Manenzhe, Malibongwe S. Manono, Jennifer G. Wiese, Benjamin Musuku, and Kirsten C. Corin
Elsevier BV
Mahlogonolo Nkadimeng, Malibongwe S. Manono, and Kirsten C. Corin
MDPI
Tanaka P. Tafirenyika, Cyril T. O’Connor, and Kirsten C. Corin
MDPI AG
Beneficiation of sulphide ores by flotation is ascribed to the natural electrochemical activity associated with sulphide minerals. Flotation is an electrochemical process comprising many interdependent conditions that are difficult to decouple in terms of controlling flotation performance. The extent of electrochemical activity is mineral dependent and can be measured against a reference cell to differentiate between minerals. This difference in activity is known as the rest potential. The rest potential can be exploited to preferentially float one mineral over another as these properties result in different regions of flotation stability for different minerals. Bornite and chalcocite present an interesting study because when measured against the standard hydrogen electrode (SHE), there is a small difference in rest potential; bornite has a potential of 0.44 V and chalcocite a potential of 0.40 V. The key differentiating factor between the two minerals is the presence of iron in bornite (Cu5FeS4) and the lack thereof in chalcocite (Cu2S). This study considers bornite and chalcocite microflotation, adsorption studies and zeta potential measurements, and three key factors were explored: pH, galvanic interactions and collector adsorption. The overall objective of the study is to understand the response of bornite and chalcocite to changes in pulp chemistry.
Nolihle Ndamase, Margreth Tadie, and Kirsten Claire Corin
MDPI AG
Water is used as a liquid medium as well as a means of transportation during mining operations. Flotation, in particular, is a water intensive process where water makes up about 80–85% of the pulp phase. Process water contains organic and inorganic species which accumulate as they are recycled. To avoid the treatment costs of removing these contaminants, many mining operations allow the quality of their water to degrade over time. When this water is introduced into flotation circuits, the pulp chemistry is altered. Ionic species that accumulate in recycled process water have been shown by previous studies to be especially deleterious to flotation performance. Such ions include Ca2+, Cu2+, Mg2+, Pb2+, SO42− and S2O32−, amongst others. The flotation sub-process of collector adsorption which is responsible for inducing hydrophobicity on valuable mineral surfaces may be influenced by water chemistry. Accumulating ionic species have been shown to hinder collector adsorption which may reduce recovery of valuable minerals to the concentrate. Consequently, degrading water quality may threaten the economic viability of mining operations that make use of closed water circuits. Electrochemical techniques such as mineral rest potentials can be used to monitor the impact of changing water quality on collector–mineral interactions. Microflotation was used to determine whether mineral floatability was affected by changing water quality. This study therefore aimed to investigate whether electrochemical techniques such as rest potential measurements can be used to predict flotation performance under changing water quality. No definable relationship was found between the rest potential differences and the microflotation initial recoveries, however, rest potential measurements did identify the negative impact that thiosulphate ions may have on flotation processes.
Jestos Taguta, Zandile Peku, Nthapo Sehlotho, and Kirsten Corin
MDPI AG
Water scarcity is compelling mining houses to not only recycle process water but to also identify alternative sources of make-up water in concentrators. South Africa has significant volumes of acid mine drainage (AMD) generated from vast mining operations. This study investigated the viability of using AMD as a replacement for potable water in the flotation of a platinum-group-minerals (PGM)-bearing Merensky ore. Rougher and cleaner flotation testwork was conducted at laboratory scale to compare the performances of potable water (baseline water), AMD treated with Ca(OH)2, and AMD treated with the Veolia process. Water analysis showed that the three water types differed in pH, water hardness, conductivity, and total dissolved solids. The results showed the AMD treated with Ca(OH)2 was detrimental to PGM recovery compared to potable water at depressant dosages of 50 g/t. Specifically, AMD treated with Ca(OH)2 achieved a PGM rougher recovery of 67.8%, while potable water achieved a PGM rougher recovery of 88.4%. Depressant dosage optimisation and treatment of the AMD using the Veolia process were investigated as potential strategies to mitigate the detrimental effects of the AMD treated with Ca(OH)2 on the flotation performance of a Merensky ore. The AMD treated with the Veolia process achieved a PGM rougher recovery of 70.8%. Thus, treatment of the AMD was beneficial, though the PGM and base metal sulphides (BMS) recoveries were still lower than those achieved in potable water. Reducing the depressant dosage to 25 g/t in AMD treated with Ca(OH)2 resulted in the highest PGM, Cu, and Ni rougher recoveries of 91%, 60.2%, and 58%, respectively. The AMD treated with Ca(OH)2 at lower depressant dosage outperformed the potable water in terms of PGM and BMS recoveries and concentrate grades, indicating that AMD has the potential to replace potable water as make-up water in Merensky ore processing plants. The results showed that depressant optimisation is important to achieve superior metallurgical results when using AMD treated with Ca(OH)2. The use of AMD in Merensky ore processing plants not only conserves freshwater in minerals processing plants but also reduces high volumes of contaminated effluents.
Kirsten C Corin, Sarah Tetlow, and Malibongwe S Manono
Elsevier BV
Kirsten Corin, Mariette Smart, and Malibongwe Manono
MDPI AG
The products of mining are key to the technology development of the future [...]
Malibongwe Manono and Kirsten Corin
MDPI AG
The mining and mineral processing of Cu-Ni-PGM sulfide ores in South Africa occurs in semi-arid regions. The scarcity of water resources in these regions has become one of the biggest challenges faced by mineral concentrators. As a result, concentrators are forced to find ways through which they can manage and control their water usage. The recycling and re-use of process water in mineral concentration plants has therefore become a common practice. This practice is beneficial in that it reduces reliance on municipal water and harnesses compliance to stringent environmental regulations on freshwater usage. This approach also offers a better response to the Sustainable Development Goals (SDGs) for the mining industry, as water and its preservation form part of the SDGs. This practice could, however, be somewhat concerning to a process operator because recirculated water often has higher concentrations of ions compared to fresh or potable water. This is because an unintended change in the process water quality may affect critical aspects of flotation such as the stability of the froth. This issue has led to the need for both the mining industry and researchers in the field to find the ions in process water that have the greatest impact on froth stability. Thus, the authors of this study investigated the effects of various ions common in the process water of a typical Cu-Ni-PGM ore on froth stability using a 3 L bench scale flotation cell. Solids and water recoveries were used as proxies for froth stability. These were further complemented by bubble size, water recoveries, foam height, and dynamic foam stability from two-phase flotation systems. A two-phase foam study resulted in observations that supported findings from a three-phase study. Generally, single salt solutions containing Ca2+ and Mg2+ ions resulted in higher water recoveries both in the two-phase foam and three-phase froth studies, increases in foam heights and dynamic foam stability, and a decrease in bubble size compared to the solutions that contained Na+. SO42− also resulted in increased foam stability compared to Cl− and NO3−. These results showed that the divalent inorganic electrolytes—Ca2+, Mg2+, and SO42−—were more froth- and foam-stabilizing than the monovalent inorganic electrolytes—Cl−, NO3−, and Na+. This finding was in agreement with previous research. The findings of this study are deemed crucial in the development of a process water management protocol in sulfidic Cu-Ni-PGM ore concentrators. However, more comparative three-phase froth stability tests are needed as subjects of future investigative work to further ascertain specific ion effects on froth stability in sulfide ores.
Ngoni Mhonde, Leena-Sisko Johansson, Kirsten Corin, and Nora Schreithofer
Informa UK Limited
ABSTRACT This study investigated the impact of tetrathionate ions on selected sulfide mineral surfaces and their flotation response to tetrathionates using X-ray photoelectron spectroscopy (XPS), zeta potential and batch flotation studies and linking the results to previously reported electrochemistry, FTIR and microflotation studies. XPS revealed that tetrathionates have the propensity to oxidize minerals, changing the chemical composition of the mineral surface. This surface alteration renders the sulfide minerals hydrophilic through sulphoxy and hydroxy entities reducing collector adsorption as noted in FTIR and mixed potential studies. Zeta potentials showed little specific adsorption of tetrathionates on the sulfides except at moderately high concentrations, i.e., 1000 mg/L. Batch flotation showed that tetrathionates in solution depressed sulfide minerals, particularly galena, reducing its recovery to the concentrates in support of earlier microflotation results.
Lisa Louise October, Malibongwe Shadrach Manono, Kirsten Claire Corin, Nora Schreithofer, and Jenny Gael Wiese
American Chemical Society (ACS)
Previous studies have considered the effect of using recycled process water in froth flotation and whether certain ions are responsible for what is observed in the final concentrate in terms of mineral grades and recoveries. The attachment of mineral particles to air bubbles is a fundamental subprocess of flotation, without which separation of valuable minerals from nonvaluables cannot occur; it is, therefore, of interest to assess the effect of specific ionic species on bubble–particle attachment. The effects of oxyhydroxo species on bubble−particle interactions were studied with three synthetic plant water (SPWs) of increasing ionic strengths at pH 11 as it is known to through solution speciation that at this pH, oxyhydroxo species may be present in significant concentrations. The presence of these oxyhydroxo species such as magnesium and calcium hydroxides in alkaline pulps were confirmed by many researchers and proven to affect bubble and particle surface charges. Furthermore, to ascertain whether there were certain ions within the plant water that impacted the bubble–particle attachment more significantly than others, tests were carried out with carefully selected single salt solutions. The SPWs at pH 11 resulted in very poor pyrrhotite attachment probabilities and recoveries as compared to the attachment probabilities and recoveries that were obtained with these waters at pH 6.5. Increasing the ionic strength of SPWs resulted in a decrease in pyrrhotite attachment probabilities more evidently at pH 11. Thus, it can be concluded that the presence of CaOH+, (MgOH)2, and MgOH+ species hinders the flotation of pyrrhotite particles. Studies on selected single salts showed that Na+ resulted in better pyrrhotite attachment probability and recovery compared to Ca2+. Furthermore, upon studying the anion effect, SO42– performed better than NO3– when paired with Ca2+, thus indicating a negative effect on flotation response when Ca2+ and NO3– ions are used together. These results can be attributed to the action of species such as Ca2+, CaNO3+, and CaSO4(aq.) on the zeta potential and their consequential effect on the electrical double layer. The outcomes of this work should be of significant importance for an effective management of ions in recycled process water in the froth flotation process.
Ngoni Mhonde, Leena-Sisko Johansson, Kirsten Corin, and Nora Schreithofer
Elsevier BV
Ngoni Mhonde, Leena-Sisko Johansson, Kirsten Corin, and Nora Schreithofer
Elsevier BV
L.L. October, M.S. Manono, J.G. Wiese, N. Schreithofer, and K.C. Corin
Elsevier BV
Kirsten Corin, Belinda McFadzean, Natalie Shackleton, and Cyril O’Connor
MDPI AG
In order to increase the recovery of PGMs by flotation, it is necessary to optimise the liberation of the key minerals in which the platinum group elements (PGEs) are contained which include sulphides, arsenides, tellurides, and ferroalloys among others, while at the same time ensuring the optimal depression of gangue minerals. In order to achieve this, comminution circuits usually consist of two or three stages of milling, in which the first stage is autogeneous, followed by ball milling. Further liberation is achieved in subsequent stages using ultra-fine grinding. Each comminution stage is followed by flotation in the so-called MF2 or MF3 circuits. While this staged process increases overall recoveries, overgrinding may occur, hence creating problems associated with fine particle flotation. This paper presents an overview of the mineralogy of most of the more significant PGM ores processed in South Africa and the various technologies used in comminution circuits. The paper then summarises the methodology used in flotation circuits to optimise recovery of fine particles in terms of the collectors, depressants, and frothers used. The effect of entrainment, slimes coating, changes in rheology caused by the presence of a significant amount of fines and of chromite recovery is addressed.
Mathew Dzingai, Malibongwe S. Manono, and Kirsten C. Corin
MDPI AG
Water scarcity necessitates the recycling of process water within mineral processing practices. This may however come with its disadvantages for unit operations such as froth flotation as this process is water intensive and sensitive to water chemistry. It is therefore important to monitor the water chemistry of the recycle stream of process water and any other water source to flotation. Monitoring the concentrations of the anions in recycled process water is therefore important to consider as these are speculated to impact flotation performance. Batch flotation tests were conducted using synthetically prepared plant water (3 SPW) with a TDS of 3069 mg/L as the baseline experiment. 3 SPW contained 528 mg/LNO3− and 720 mg/L SO42−, other anions and cations, and no S2O32−. Upon spiking 3 SPW with selected anions, viz, NO3−, SO42− and S2O32−, it was noted that NO3− and SO42− exhibited threshold concentrations while S2O32− did not show a threshold concentration for both copper and nickel grade. Spiking 3 SPW with 352 mg/L more of NO3− to a total 880 mg/L NO3− concentration resulted in the highest copper and nickel grade compared to 3 SPW while increasing the S2O32− from 60 to 78 mg/L increased nickel and copper grade. 720 to 1200 mg/L SO42− and 528 to 880 mg/L NO3− were deemed the concentration boundaries within which lies the threshold concentration above which flotation performance declines with respect to metal grades, while for S2O32− the threshold concentration lies outside the range considered for this study. Anion distribution between the pulp and the froth did not seem to impact the recovery of copper or nickel. Notably, the correlation between the concentrate grades and anion distribution between the froth and the pulp seemed to be ion dependent.
Ngoni Mhonde, Leena Pitkänen, Kirsten Corin, and Nóra Schreithofer
MDPI AG
Tetrathionates have been found in significantly high concentrations in recycled process waters from massive sulphide ore processing plants. These polythionates react with xanthate added to flotation pulps thus reducing xanthate dosages in solution potentially affecting flotation performance. The current study focused on the effect of the tetrathionate-xanthate reaction on sulphide mineral recoveries. Ore dissolution studies confirmed the generation of tetrathionates by copper-lead-zinc ores. In 20 min, the tetrathionates consumed more than half of the xanthate in solution at pH 7. Rest potential measurements and Fourier transform infrared spectroscopy (FTIR) showed that the degree of collector-mineral interactions of xanthate and both galena and chalcopyrite was greatly reduced in the presence of a 2000 mg/L tetrathionate solution. Microflotation tests showed that chalcopyrite recovery was less sensitive to tetrathionates as indicated by small changes in mineral recoveries. Galena was sensitive to the action of tetrathionates on the mineral surface as the galena recovery significantly declined when floated with xanthate as a collector in both a 500 mg/L tetrathionate solution and a 2000 mg/L tetrathionate solution. These fundamental results lay a sound base on which more discussion into the significance and the effect of tetrathionates on flotation performance of sulphide ores can be developed.
Mathew Dzingai, Malibongwe Manono, and Kirsten Corin
MDPI AG
Froth flotation is a multifaceted complex process which is water intensive. The use of recycled water as an alternative source of water to meet water demands of the process may introduce deleterious inorganic ions that affect the mineral surface, pulp chemistry, and reagent action, hence the need to establish whether threshold ion concentrations exist beyond which flotation performance will be adversely affected. This is of paramount importance in informing appropriate recycle streams and allowing simple, cost-effective water treatment methods to be applied. Here we report that increasing ionic strengths of synthetic plant water (SPW); 3, 5, and 10 SPW respectively, resulted in an increase in water recovery in the order 0.073 mol·dm−3 (3 SPW) < 0.121 mol·dm−3 (5 SPW) < 0.242 mol·dm−3 (10 SPW), indicating an increase in froth stability as higher water recoveries are linked to increased froth stabilities. This behavior is linked to the action of inorganic electrolytes on bubble coalescence which is reported in literature. There was, however, no significant effect on the valuable mineral recovery. Spiking 3 SPW to 400 mg/L Ca2+ resulted in higher copper and nickel grades compared to 3 SPW, 5 SPW, and 10 SPW and was deemed to be the Ca2+ ion threshold concentration for this study since 3 SPW spiked with further Ca2+ to a concentration of 800 mg/L resulted in a decrease in the concentrate grade. The spiking of 3 SPW with Mg2+ resulted in higher copper and nickel grades compared to all other synthetic plant water conditions tested in this study.
Ngoni Mhonde, Nora Schreithofer, Kirsten Corin, and Mikko Mäkelä
MDPI AG
The combined effect of dissolved ions and water temperature on the adsorption of a xanthate collector on chalcopyrite and pentlandite was investigated using multiple linear regression. Cationic species improved the adsorption of the collector on sulphide minerals through xanthate adsorption activation. Thiosulphate ions generally had a negative effect on collector adsorption, and the interaction of thiosulphate ions and cations effectively reduced collector adsorption on the sulphide minerals. With regards to temperature variation caused by seasonal variation, this study suggests that temperature can influence the adsorption of collectors in the flotation process and this should be approached on a case by case basis as it seems to differ with the type of mineral under investigation. These fundamental results prompt a discussion on how complex water matrices can affect interactions of reagents and sulphide minerals at the solid–liquid interface and the possible effect on flotation performance.
Ngoni Mhonde, Mariette Smart, Kirsten Corin, and Nora Schreithofer
MDPI AG
High microbial cell counts have been recorded in sewage waters employed as process water in mineral beneficiation plants across the world. The presence of these microbes can negatively impact flotation performance through mineral passivation, although some microbes improve flotation performance as investigated in various bio-flotation studies. The current study aims to understand the electrochemical behaviour of minerals in the presence of a sodium ethyl xanthate (SEX) collector and microbes originating from a sulphide ore processing plant in South Africa. The electrochemical response was correlated to observe flotation performance. Mixed potential measurements were conducted in parallel to microflotation tests, to assess the hydrophilicity or hydrophobicity induced on sulphide minerals adapted to microbe-laden synthetic plant water. Sulphide minerals’ mixed potentials and interactions of SEX with sulphide minerals were dramatically reduced in the presence of the mixed microbial community (MMC). The observations were correlated with poor flotation efficacy noted in microflotation tests. These fundamental results shed light on how the adsorption of thiol collectors on sulphide minerals is adversely affected by microbes, prompting a discussion on flotation process monitoring when mineral beneficiation is conducted using microbe-laden water.
L.L. October, K.C. Corin, M.S. Manono, N. Schreithofer, and J.G. Wiese
Elsevier BV
Malibongwe Shadrach Manono, Kirsten Claire Corin, and Jennifer Gael Wiese
Frontiers Media SA
Mineral concentrators are becoming increasingly aware of the importance of the quality of the water that they feed into their milling and flotation circuits. It is speculated that different inorganic constituents of process water may yield different flotation results owing to the electrolyte–reagent–mineral interactions occurring in the pulp phase. These interactions are said to be specific to ion type, reagent type, and mineral or ore type. It therefore stands to reason that there is a need to develop an understanding of the specific ion effects on both the pulp phase and the froth phase phenomena, such that the chemistry and the quality of process water can be monitored and controlled in a manner that does not negatively affect the flotation performance. Previous research has shown that inorganic electrolytes may impact the hydrophobicity and the floatability of mineral particles and could in turn affect froth stability, entrainment, and thus mineral grades and recoveries. In this study, the floatability of a Cu-Ni-PGM-bearing Merensky ore is tested on a bench-scale flotation system in various single salt solutions, viz., CaCl2, CaSO4, Ca(NO3)2, MgCl2, Mg(NO3)2, MgSO4, NaCl, NaNO3, and Na2SO4, in order to examine specific ion effects on gangue recovery. Coagulation and zeta potential tests are conducted in order to establish the nature of the impact that specific ions have on the behavior of gangue in flotation. The findings of this work have shown that single salt solutions containing NO3- ions resulted in a strong depression of gangue compared to those solutions containing Cl− and SO42− ions. It was also shown that the divalent Ca2+ and Mg2+ showed a stronger depression of gangue compared to the monovalent Na+. Ca2+, in comparison to Na+, resulted in an increase in the coagulation of the ore as well as an increase in the zeta potential of talc. Overall, the findings of this paper suggest that the presence of Ca2+ and Mg2+ in process water would most likely create conditions that promote gangue depression.