An investigation into hydrochloric acid leaching of low grade gold-bearing material and oxidized cobalt-copper ores
- Authors: Apua, Momboyo Clotilde
- Date: 2012-06-07
- Subjects: Leaching , Hydrochloric acid , Reduction (Chemistry)
- Type: Thesis
- Identifier: uj:8652 , http://hdl.handle.net/10210/5008
- Description: M.Tech. , The efficiency of hydrochloric acid leaching of gold from low grade gold-bearing material has been investigated in the presence of sodium hypochlorite (NaOCl) to produce in situ chlorine gas which is an oxidizing agent able to oxidize gold metal to gold soluble forms: Au+ and Au3+. The effect of concentrations of HCl, NaOCl, and mixtures HCl + NaOCl was sought. An investigation on chlorine species was conducted to predict their stability areas. The reactions involved and their mechanisms were established. Prior to leaching, the feed was subjected to fire assay, Atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR) analyses, to quantify the various elements, and to find out the chemical composition and the different mineralogical phases which are present. The main minerals found in the feed were: quartz, pyrite, muscovite-2M1, (M); and clinochlore. The grade was found to be 0.62 g/t. It was found from the hydrochloric acid leaching process that most of metals constituents (iron and potassium) of the feed were leached and consumed all the hydrochloric acid. Therefore, leaching of gold from low grade gold-bearing materials in aqueous chlorine solution is not an effective process for now. Hydrochloric acid leaching of cobalt and copper from four oxidized cobalt-bearing ores was studied in the presence of FeCl2 to produce in situ Fe2+ that is a reducing agent able to reduce Co3+ to Co2+ which is the soluble form of cobalt. The effects of the concentrations of HCl, FeCl2, mixture HCl + FeCl2, leaching time, particle size, and the dissolution kinetics were investigated. Prior to leaching the feeds were characterized with XRD, XRF, FTIR, AAS, Scanning electron microscopy (SEM), and gravimetric analysis. Cobalt contents were found to be between 2.59% and 39.76% in the four ores namely, high Cu ore, high Co ore, low Co ore, and high Co ore with mica. Effect of FeCl2 concentrations in HCl solutions involving 35.06 g; 70.13 g; and 105.18 g corresponding to 0.25 M; 0.5 M; and 0.75 M respectively, were studied and the reactions mechanism established. It was found that an increase in FeCl2 concentration increases the Co dissolution due to the reduction of Co3+ into Co2+ which is soluble. High Co extractions of 99%, 99%, 99%, and 95% were obtained when mixtures 1 M HCl + 105.18 g FeCl2 were used as lixiviants for high Cu ore, high Co ore, low Co ore, and high cobalt ore with mica, respectively. Copper recoveries of 88%, 77%, 75%, and 86% were obtained for high Cu ore, high Co ore, low Co ore, and high Co ore with mica, respectively. The increase in FeCl2 concentration did not have any important effect on the Cu extraction. Mechanisms of involved reactions were established. The order of cobalt leaching reaction was found to be 2 with respect to cobalt concentration. Optimum leaching conditions were found to be: leaching time: 30 minutes, reagent concentrations: mixture 1 M HCl + 105.18 g FeCl2, S/L ratio = 1:20, stirring speed avoiding the vortex, room temperature, pH values from 2.28 to 0.03, and ORP values from 0.402 to 0.322 V.
- Full Text:
- Authors: Apua, Momboyo Clotilde
- Date: 2012-06-07
- Subjects: Leaching , Hydrochloric acid , Reduction (Chemistry)
- Type: Thesis
- Identifier: uj:8652 , http://hdl.handle.net/10210/5008
- Description: M.Tech. , The efficiency of hydrochloric acid leaching of gold from low grade gold-bearing material has been investigated in the presence of sodium hypochlorite (NaOCl) to produce in situ chlorine gas which is an oxidizing agent able to oxidize gold metal to gold soluble forms: Au+ and Au3+. The effect of concentrations of HCl, NaOCl, and mixtures HCl + NaOCl was sought. An investigation on chlorine species was conducted to predict their stability areas. The reactions involved and their mechanisms were established. Prior to leaching, the feed was subjected to fire assay, Atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR) analyses, to quantify the various elements, and to find out the chemical composition and the different mineralogical phases which are present. The main minerals found in the feed were: quartz, pyrite, muscovite-2M1, (M); and clinochlore. The grade was found to be 0.62 g/t. It was found from the hydrochloric acid leaching process that most of metals constituents (iron and potassium) of the feed were leached and consumed all the hydrochloric acid. Therefore, leaching of gold from low grade gold-bearing materials in aqueous chlorine solution is not an effective process for now. Hydrochloric acid leaching of cobalt and copper from four oxidized cobalt-bearing ores was studied in the presence of FeCl2 to produce in situ Fe2+ that is a reducing agent able to reduce Co3+ to Co2+ which is the soluble form of cobalt. The effects of the concentrations of HCl, FeCl2, mixture HCl + FeCl2, leaching time, particle size, and the dissolution kinetics were investigated. Prior to leaching the feeds were characterized with XRD, XRF, FTIR, AAS, Scanning electron microscopy (SEM), and gravimetric analysis. Cobalt contents were found to be between 2.59% and 39.76% in the four ores namely, high Cu ore, high Co ore, low Co ore, and high Co ore with mica. Effect of FeCl2 concentrations in HCl solutions involving 35.06 g; 70.13 g; and 105.18 g corresponding to 0.25 M; 0.5 M; and 0.75 M respectively, were studied and the reactions mechanism established. It was found that an increase in FeCl2 concentration increases the Co dissolution due to the reduction of Co3+ into Co2+ which is soluble. High Co extractions of 99%, 99%, 99%, and 95% were obtained when mixtures 1 M HCl + 105.18 g FeCl2 were used as lixiviants for high Cu ore, high Co ore, low Co ore, and high cobalt ore with mica, respectively. Copper recoveries of 88%, 77%, 75%, and 86% were obtained for high Cu ore, high Co ore, low Co ore, and high Co ore with mica, respectively. The increase in FeCl2 concentration did not have any important effect on the Cu extraction. Mechanisms of involved reactions were established. The order of cobalt leaching reaction was found to be 2 with respect to cobalt concentration. Optimum leaching conditions were found to be: leaching time: 30 minutes, reagent concentrations: mixture 1 M HCl + 105.18 g FeCl2, S/L ratio = 1:20, stirring speed avoiding the vortex, room temperature, pH values from 2.28 to 0.03, and ORP values from 0.402 to 0.322 V.
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Investigation of copper recovery rate from copper oxide ore occurring as coarse grains locked in a porphyritic fine grain alumina and silica
- Emmanuel, Bamidele, Ajayi, John Ade, Makhatha, Elizabeth
- Authors: Emmanuel, Bamidele , Ajayi, John Ade , Makhatha, Elizabeth
- Date: 2019
- Subjects: Leaching , Copper oxide , Temperature
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/291105 , uj:31604 , Citation: Emmanuel, B., Ajayi, J.A. & Makhatha, E. 2019. Investigation of copper recovery rate from copper oxide ore occurring as coarse grains locked in a porphyritic fine grain alumina and silica. Energy Procedia 157 (2019) 972–976
- Description: Abstract: An investigation was carried out on a high grade copper oxide ore to determine the optimum recovery rate of copper from the pregnant leached solution obtained from leaching the ore in a sulfuric acid lixiviant. The copper oxide ore occur in coarse grains locked in a porphyritic fine grain alumina and silica. 800 g of copper oxide ore was obtained at the deposit; the samples were chemically and mineralogically analyzed. The analysis shows that the copper oxide ore contain 19.52 % copper extraction. The ore samples were crushed to sizes within 5 cm and 12 cm. The crushed samples were then grinded to a mesh size of -150 µm. This size was used to conduct the leaching process and sulfuric acid was used as the lixiviant. Parameters varied in this study include: the concentration of acid, temperature and time. The pregnant leach solution obtained was analyzed and the results showed an increase in the % recovery of copper as the molar concentration of H2SO4 increases from 0.25M to 1M and the % copper extraction decreases as the acid concentration increases from 1 M to 3 M. Higher copper recovery of 32.13 % was observed at elevated temperature of up to 80oC. These findings suggest the possibility of effectively producing copper from the Pingel-Bauchi Deposit through hydrometallurgical extraction process; optimum recovery can be obtained at an elevated temperature using acid concentration of 1 M.
- Full Text:
- Authors: Emmanuel, Bamidele , Ajayi, John Ade , Makhatha, Elizabeth
- Date: 2019
- Subjects: Leaching , Copper oxide , Temperature
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/291105 , uj:31604 , Citation: Emmanuel, B., Ajayi, J.A. & Makhatha, E. 2019. Investigation of copper recovery rate from copper oxide ore occurring as coarse grains locked in a porphyritic fine grain alumina and silica. Energy Procedia 157 (2019) 972–976
- Description: Abstract: An investigation was carried out on a high grade copper oxide ore to determine the optimum recovery rate of copper from the pregnant leached solution obtained from leaching the ore in a sulfuric acid lixiviant. The copper oxide ore occur in coarse grains locked in a porphyritic fine grain alumina and silica. 800 g of copper oxide ore was obtained at the deposit; the samples were chemically and mineralogically analyzed. The analysis shows that the copper oxide ore contain 19.52 % copper extraction. The ore samples were crushed to sizes within 5 cm and 12 cm. The crushed samples were then grinded to a mesh size of -150 µm. This size was used to conduct the leaching process and sulfuric acid was used as the lixiviant. Parameters varied in this study include: the concentration of acid, temperature and time. The pregnant leach solution obtained was analyzed and the results showed an increase in the % recovery of copper as the molar concentration of H2SO4 increases from 0.25M to 1M and the % copper extraction decreases as the acid concentration increases from 1 M to 3 M. Higher copper recovery of 32.13 % was observed at elevated temperature of up to 80oC. These findings suggest the possibility of effectively producing copper from the Pingel-Bauchi Deposit through hydrometallurgical extraction process; optimum recovery can be obtained at an elevated temperature using acid concentration of 1 M.
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Kinetic and thermodynamic parameters of silica leaching from Camden power station fly ash
- Falayi, Thabo, Ntuli, Freeman, Okonta, Felix Ndubisi
- Authors: Falayi, Thabo , Ntuli, Freeman , Okonta, Felix Ndubisi
- Date: 2015
- Subjects: Fly ash , Leaching , Potassium silicate , Silicate leaching
- Type: Article
- Identifier: uj:5142 , ISBN 978-1-61804-270-5 , http://hdl.handle.net/10210/14120
- Description: Fly ash from a South African power station ash dam was used. The fly ash approximated Class F fly ash but had a loss on ignition greater than 6%. The leaching parameters investigated were leaching time, KOH concentration, agitation speed, fly ash particle size, leaching temperature and liquid solid ratio (L/S). It was found that the optimum leaching conditions were leaching time of 6 h, 3M KOH, 500 rpm agitation speed, 25 L/S ratio, leaching temperature of 100˚C. Silica leaching followed a modified Jander equation kinetics with an N value of 1.48 and an activation energy of 5.9 kJ/mol.
- Full Text:
- Authors: Falayi, Thabo , Ntuli, Freeman , Okonta, Felix Ndubisi
- Date: 2015
- Subjects: Fly ash , Leaching , Potassium silicate , Silicate leaching
- Type: Article
- Identifier: uj:5142 , ISBN 978-1-61804-270-5 , http://hdl.handle.net/10210/14120
- Description: Fly ash from a South African power station ash dam was used. The fly ash approximated Class F fly ash but had a loss on ignition greater than 6%. The leaching parameters investigated were leaching time, KOH concentration, agitation speed, fly ash particle size, leaching temperature and liquid solid ratio (L/S). It was found that the optimum leaching conditions were leaching time of 6 h, 3M KOH, 500 rpm agitation speed, 25 L/S ratio, leaching temperature of 100˚C. Silica leaching followed a modified Jander equation kinetics with an N value of 1.48 and an activation energy of 5.9 kJ/mol.
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An attempt into identification of suitable recovery process for nickel value from nickel sulfide ore and tailings
- Authors: Madiba, Mapilane S.
- Date: 2013-11-25
- Subjects: Nickel - Metallurgy , Nickel sulfide , Tailings (Metallurgy) , Leaching
- Type: Thesis
- Identifier: uj:7796 , http://hdl.handle.net/10210/8691
- Description: M.Tech (Metallurgy) , Nickel in South Africa is scarce. Other than as a by-product from platinum mining, its only source is the Uitkomst Complex, a satelite of the Bushveld Igneous Complex, located between Machadodorp and Barberton and mined by Nkomati Nickel. Pentlandite occurs as the main nickel-bearing mineral, disseminated within a sulfide matrix of pyrrhotite, pyrite and chalcopyrite. Accessories are of chromite and platinum in solid solution with the sulfides. The sulfides are hosted in mainly ultramafic rocks. The presence of talc is of particular nuisance. Head grade is in the decline, from earlier 0.7 to more recently 0.3% or even lower. Standard froth flotation yields a concentrate of 7 – 9% nickel at a recovery of up to 70%. A higher nickel recovery from such low – grade feed stock would be desirable. To achieve these two methods were investigated and reported in the following: Non-oxidative leaching as an alternative to flotation, using strong hydrochloric and sulfuric acid and also aqueous ammonia solutions at various liquid-to-solid ratios. Only the degree of nickel dissolution over time at room temperature was studied and no attempt was made to recover the dissolved metal from solution. Froth flotation after pre-treatment with microwaves at various power levels and over various periods of time of irradiation. It was surmised that a certain amount of inter-granular cracking could thus be achieved that would improve the flotation behavior in respect of grade and recovery. An extensive literature study, in particular, of the nature of microwaves, their interaction with matter and possible metallurgical benefits derived as a consequence of such interaction, forms part of the investigation and is reported in detail. A lot of theoretical and experimental work has been done in this respect, although the obtained results were not conclusive.
- Full Text:
- Authors: Madiba, Mapilane S.
- Date: 2013-11-25
- Subjects: Nickel - Metallurgy , Nickel sulfide , Tailings (Metallurgy) , Leaching
- Type: Thesis
- Identifier: uj:7796 , http://hdl.handle.net/10210/8691
- Description: M.Tech (Metallurgy) , Nickel in South Africa is scarce. Other than as a by-product from platinum mining, its only source is the Uitkomst Complex, a satelite of the Bushveld Igneous Complex, located between Machadodorp and Barberton and mined by Nkomati Nickel. Pentlandite occurs as the main nickel-bearing mineral, disseminated within a sulfide matrix of pyrrhotite, pyrite and chalcopyrite. Accessories are of chromite and platinum in solid solution with the sulfides. The sulfides are hosted in mainly ultramafic rocks. The presence of talc is of particular nuisance. Head grade is in the decline, from earlier 0.7 to more recently 0.3% or even lower. Standard froth flotation yields a concentrate of 7 – 9% nickel at a recovery of up to 70%. A higher nickel recovery from such low – grade feed stock would be desirable. To achieve these two methods were investigated and reported in the following: Non-oxidative leaching as an alternative to flotation, using strong hydrochloric and sulfuric acid and also aqueous ammonia solutions at various liquid-to-solid ratios. Only the degree of nickel dissolution over time at room temperature was studied and no attempt was made to recover the dissolved metal from solution. Froth flotation after pre-treatment with microwaves at various power levels and over various periods of time of irradiation. It was surmised that a certain amount of inter-granular cracking could thus be achieved that would improve the flotation behavior in respect of grade and recovery. An extensive literature study, in particular, of the nature of microwaves, their interaction with matter and possible metallurgical benefits derived as a consequence of such interaction, forms part of the investigation and is reported in detail. A lot of theoretical and experimental work has been done in this respect, although the obtained results were not conclusive.
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Quantitative leaching of nickel from jarosite using sulphuric acid
- Authors: Makhatha, M. E , Nheta, W.
- Date: 2013
- Subjects: Sulphuric acid , Nickel , Jarosite , Leaching
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15446 , uj:15662 , Citation: Makhatha, M.E., Nheta, W. & Lamya, R. 2013. Quantitative leaching of nickel from jarosite using sulphuric acid. 23rd International Mining Congress and Exhibition of Turkey, 16-19 April, Antalya
- Description: Abstract: Please refer to full text to view abstract
- Full Text: false
- Authors: Makhatha, M. E , Nheta, W.
- Date: 2013
- Subjects: Sulphuric acid , Nickel , Jarosite , Leaching
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15446 , uj:15662 , Citation: Makhatha, M.E., Nheta, W. & Lamya, R. 2013. Quantitative leaching of nickel from jarosite using sulphuric acid. 23rd International Mining Congress and Exhibition of Turkey, 16-19 April, Antalya
- Description: Abstract: Please refer to full text to view abstract
- Full Text: false
Leaching kinetics on the removal of phosphorus from waste phosphogypsum by application of shrinking core model
- Mashifana, Tebogo, Ntuli, Freeman, Okonta, Felix
- Authors: Mashifana, Tebogo , Ntuli, Freeman , Okonta, Felix
- Date: 2018
- Subjects: Phosphogypsum , Leaching , Kinetics
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/286415 , uj:30991 , Citation: Mashifana, T., Ntuli, F. & Okonta, F. 2018. Leaching kinetics on the removal of phosphorus from waste phosphogypsum by application of shrinking core model. South African Journal of Chemical Engineering, 27:1-6. https://doi.org/10.1016/j.sajce.2018.11.001
- Description: Abstract: This study investigated the removal of phosphorus from waste phosphogypsum by using citric acid as a leaching reagent, evaluated the potential environmental effect of the final product produced and provide recommenda- tions for the application of developed products. A dissolution process was applied and three variables were studies namely, concentration, stirring speed and temperature. The results showed that Phosphorus can suc- cessfully be removed from waste phosphogypsum and the optimum leaching conditions were at the con- centration of 0.5 M and temperature of 40 °C, with no effect observed on varying the stirring speed. Shrinking core model (SCM) was used to determine the best fit for the experimental data. For the pore diffusion model (KD), all correlation coefficients yielded were above 0.9, illustrating a positively linear correlation of KD and leaching behavior for phosphorus. Pore diffusion proved to be the effective rate controlling mechanism for the removal of phosphorus from phosphogypsum. The analysis of moments of particle size distribution (PSD) also showed a reduction in particle size, indicating the dissolution of the solid particles. The application of Toxic Leaching Characteristic Procedure (TLCP) showed low concentrations on the effluent, indicating that the de- veloped product will not contaminate the environment through leaching. The obtained leachate concentrations were within the South African effluent discharge standards. The results also showed that dissolution had a significant contribution on the moments of particle size distribution, in terms of the volume, surface area and particles number. In respect to unconfined compressive strength the products developed can be used for load bearing and as backfill material.
- Full Text:
- Authors: Mashifana, Tebogo , Ntuli, Freeman , Okonta, Felix
- Date: 2018
- Subjects: Phosphogypsum , Leaching , Kinetics
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/286415 , uj:30991 , Citation: Mashifana, T., Ntuli, F. & Okonta, F. 2018. Leaching kinetics on the removal of phosphorus from waste phosphogypsum by application of shrinking core model. South African Journal of Chemical Engineering, 27:1-6. https://doi.org/10.1016/j.sajce.2018.11.001
- Description: Abstract: This study investigated the removal of phosphorus from waste phosphogypsum by using citric acid as a leaching reagent, evaluated the potential environmental effect of the final product produced and provide recommenda- tions for the application of developed products. A dissolution process was applied and three variables were studies namely, concentration, stirring speed and temperature. The results showed that Phosphorus can suc- cessfully be removed from waste phosphogypsum and the optimum leaching conditions were at the con- centration of 0.5 M and temperature of 40 °C, with no effect observed on varying the stirring speed. Shrinking core model (SCM) was used to determine the best fit for the experimental data. For the pore diffusion model (KD), all correlation coefficients yielded were above 0.9, illustrating a positively linear correlation of KD and leaching behavior for phosphorus. Pore diffusion proved to be the effective rate controlling mechanism for the removal of phosphorus from phosphogypsum. The analysis of moments of particle size distribution (PSD) also showed a reduction in particle size, indicating the dissolution of the solid particles. The application of Toxic Leaching Characteristic Procedure (TLCP) showed low concentrations on the effluent, indicating that the de- veloped product will not contaminate the environment through leaching. The obtained leachate concentrations were within the South African effluent discharge standards. The results also showed that dissolution had a significant contribution on the moments of particle size distribution, in terms of the volume, surface area and particles number. In respect to unconfined compressive strength the products developed can be used for load bearing and as backfill material.
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Application of microwaves in leaching
- Authors: Mukendi, David Ngalula
- Date: 2014-05-14
- Subjects: Leaching , Gold - Metallurgy
- Type: Thesis
- Identifier: uj:11086 , http://hdl.handle.net/10210/10659
- Description: M.Tech. (Extraction Metallurgy) , Please refer to full text to view abstract
- Full Text:
- Authors: Mukendi, David Ngalula
- Date: 2014-05-14
- Subjects: Leaching , Gold - Metallurgy
- Type: Thesis
- Identifier: uj:11086 , http://hdl.handle.net/10210/10659
- Description: M.Tech. (Extraction Metallurgy) , Please refer to full text to view abstract
- Full Text:
Modeling and simulation of heat transfer between microwaves and a leachate
- Authors: Mukendi, Willy M.
- Date: 2014-05-14
- Subjects: Microwave heating , Leaching , Leachate , Microwave heating - Mathematical models , Heat - Transmission - Mathematical models
- Type: Thesis
- Identifier: uj:11087 , http://hdl.handle.net/10210/10660
- Description: M.Tech. (Mechanical Engineering Technology) , Please refer to full text to view abstract
- Full Text:
- Authors: Mukendi, Willy M.
- Date: 2014-05-14
- Subjects: Microwave heating , Leaching , Leachate , Microwave heating - Mathematical models , Heat - Transmission - Mathematical models
- Type: Thesis
- Identifier: uj:11087 , http://hdl.handle.net/10210/10660
- Description: M.Tech. (Mechanical Engineering Technology) , Please refer to full text to view abstract
- Full Text:
An investigation into the effect of temperature on the leaching of copper-matte
- Muzenda, E., Ramatsa, I.M., Ntuli, F., Belaid, M., Tshwabi, P.M
- Authors: Muzenda, E. , Ramatsa, I.M. , Ntuli, F. , Belaid, M. , Tshwabi, P.M
- Date: 2011
- Subjects: Cementation , Diffusion controlled , Leaching , Matte
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/17266 , uj:15864 , Muzenda, E. et al. 2011. An investigation into the effect of temperature on the leaching of coppermatte. World Academy of Science, engineering and Technology 76 (2011) : cited by EA Delgado, ÁO Nuñez - congresominas.co.pe
- Description: Abstract: Please refer to full text for abstract
- Full Text:
- Authors: Muzenda, E. , Ramatsa, I.M. , Ntuli, F. , Belaid, M. , Tshwabi, P.M
- Date: 2011
- Subjects: Cementation , Diffusion controlled , Leaching , Matte
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/17266 , uj:15864 , Muzenda, E. et al. 2011. An investigation into the effect of temperature on the leaching of coppermatte. World Academy of Science, engineering and Technology 76 (2011) : cited by EA Delgado, ÁO Nuñez - congresominas.co.pe
- Description: Abstract: Please refer to full text for abstract
- Full Text:
The effect of zinc ion concentration and pH on the leaching kinetics of calcined zinc oxide ore
- Muzenda, Edison, Simate, Geoffrey S.
- Authors: Muzenda, Edison , Simate, Geoffrey S.
- Date: 2011
- Subjects: Dissolution kinetics , Leaching , Zinc ions , Zinc oxide
- Type: Article
- Identifier: uj:4701 , http://hdl.handle.net/10210/10940
- Description: Previous studies on the dissolution of zinc oxide have concentrated on the effects of temperature, reagent concentration, particle size and agitation rate, among other factors. However, there is dearth data on the effect of a combination of product concentration and pH on leaching rates. This work examines the effects of the concentration of pH and zinc ions on the dissolution kinetics of zinc oxide. The results showed that the rate of zinc dissolution was greatest at lower pHs. This is because at lower pH, the concentration of acid (H+ ions) is also expected to be high (pH = log10[H+]), thus increasing the reaction kinetics in accordance with the kinetic molecular theory. The rate of reaction was found to increase with an increase in the concentration of zinc ions (Zn2+), which is in contrast to established theories. This observation can be explained by the fact that since heat energy produced (via an exothermic reaction) was continuously being dissipated through a constant temperature water bath it favoured zinc oxide dissolution. Zinc oxide ore at 62.5% purity also comprised of other metal oxides (e.g., iron, copper, manganese, etc) which were simultaneously leached. Since the solution was recycled, the concentration of iron, for example, could have also increased. Since zinc is more reactive than iron, two reaction mechanisms could have possibly been occurring at the same time, i.e., the dissolution of zinc oxide ore by sulfuric acid and the displacement of iron in solution by zinc in zinc oxide forming iron hydroxide.
- Full Text:
- Authors: Muzenda, Edison , Simate, Geoffrey S.
- Date: 2011
- Subjects: Dissolution kinetics , Leaching , Zinc ions , Zinc oxide
- Type: Article
- Identifier: uj:4701 , http://hdl.handle.net/10210/10940
- Description: Previous studies on the dissolution of zinc oxide have concentrated on the effects of temperature, reagent concentration, particle size and agitation rate, among other factors. However, there is dearth data on the effect of a combination of product concentration and pH on leaching rates. This work examines the effects of the concentration of pH and zinc ions on the dissolution kinetics of zinc oxide. The results showed that the rate of zinc dissolution was greatest at lower pHs. This is because at lower pH, the concentration of acid (H+ ions) is also expected to be high (pH = log10[H+]), thus increasing the reaction kinetics in accordance with the kinetic molecular theory. The rate of reaction was found to increase with an increase in the concentration of zinc ions (Zn2+), which is in contrast to established theories. This observation can be explained by the fact that since heat energy produced (via an exothermic reaction) was continuously being dissipated through a constant temperature water bath it favoured zinc oxide dissolution. Zinc oxide ore at 62.5% purity also comprised of other metal oxides (e.g., iron, copper, manganese, etc) which were simultaneously leached. Since the solution was recycled, the concentration of iron, for example, could have also increased. Since zinc is more reactive than iron, two reaction mechanisms could have possibly been occurring at the same time, i.e., the dissolution of zinc oxide ore by sulfuric acid and the displacement of iron in solution by zinc in zinc oxide forming iron hydroxide.
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Recovery of aluminium oxide from flint clay through H2SO4 leaching
- Muzenda, Edison, Daniels, Angus L., Belaid, Mohamed, Ntuli, Freeman
- Authors: Muzenda, Edison , Daniels, Angus L. , Belaid, Mohamed , Ntuli, Freeman
- Date: 2012
- Subjects: Flint clay , Aluminium oxide , Leaching
- Type: Article
- Identifier: uj:4690 , ISSN 978-988-19252-2-0 , http://hdl.handle.net/10210/10480
- Description: Please refer to full text to view abstract
- Full Text:
- Authors: Muzenda, Edison , Daniels, Angus L. , Belaid, Mohamed , Ntuli, Freeman
- Date: 2012
- Subjects: Flint clay , Aluminium oxide , Leaching
- Type: Article
- Identifier: uj:4690 , ISSN 978-988-19252-2-0 , http://hdl.handle.net/10210/10480
- Description: Please refer to full text to view abstract
- Full Text:
Process intensification of zinc oxide leaching process using sulphuric acid
- Napo, P., Ntuli, Freeman, Muzenda, Edison, Mollagee, Mansoor
- Authors: Napo, P. , Ntuli, Freeman , Muzenda, Edison , Mollagee, Mansoor
- Date: 2011
- Subjects: Leaching , Zinc oxide ores
- Type: Article
- Identifier: uj:4705 , ISSN 2078-0966 , http://hdl.handle.net/10210/10948
- Description: This study investigated methods of intensifying the leaching of zinc oxide ore using sulphuric acid for the improvement of zinc recovery. The factors that were investigated in this study were agitation speed, acid concentration and the feeding mechanism of reactants into the reactor (batch and semi-batch processes). Analysis of the elemental composition of the ore was performed using XRF prior to leaching and an Atomic Absorption Spectrometer (AAS) was used to determine the amount of zinc recovered. The results obtained, showed that increasing the acid concentration results in a significant increase zinc recovery...
- Full Text:
- Authors: Napo, P. , Ntuli, Freeman , Muzenda, Edison , Mollagee, Mansoor
- Date: 2011
- Subjects: Leaching , Zinc oxide ores
- Type: Article
- Identifier: uj:4705 , ISSN 2078-0966 , http://hdl.handle.net/10210/10948
- Description: This study investigated methods of intensifying the leaching of zinc oxide ore using sulphuric acid for the improvement of zinc recovery. The factors that were investigated in this study were agitation speed, acid concentration and the feeding mechanism of reactants into the reactor (batch and semi-batch processes). Analysis of the elemental composition of the ore was performed using XRF prior to leaching and an Atomic Absorption Spectrometer (AAS) was used to determine the amount of zinc recovered. The results obtained, showed that increasing the acid concentration results in a significant increase zinc recovery...
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Aqueous behaviour of cobalt in the presence of copper, iron and sulphur dioxide with and without microwave processing
- Authors: Ndalamo, John
- Date: 2009-05-19T07:40:16Z
- Subjects: Cobalt , Leaching
- Type: Thesis
- Identifier: uj:8393 , http://hdl.handle.net/10210/2558
- Description: M.Tech. , Recent studies have explored the capabilities of sulphur dioxide (SO2), a reducing agent that shows great potential to enhance the leaching efficiency of cobalt from mixed Co-Cu oxidized ores. The research study reported in this dissertation was conducted to further explore the efficacy of SO2 as a suitable reagent to improve the cobalt yield in solution from mixed Co-Cu oxidised ores. Four mixed Co-Cu oxidised ores were used in this study; namely, high cobalt ore (34% Co), low cobalt ore with mica (4% Co), low cobalt ore without mica (3% Co) and high copper ore (0.5% Co). The mechanistic leaching pathways of cobalt from these ores with and without SO2 were investigated and monitored using Ultra-Violet/Visible spectroscopy. Mineralogical studies of these ores was carried out by X - ray diffraction (XRD), X - ray fluorescence (XRF) and flame atomic absorption spectroscopy (AAS). Microwave processing of these ores prior to leaching experiments was also investigated. The experimental work was carried out on a laboratory scale and highlights of results obtained are summarized as follows: Although not much information pertaining to Co2+ bearing minerals in mixed Co-Cu oxidised ores was derived from XRD results, two forms of heterogenite minerals (CoOOH-2H and CoOOH-3R), which bear cobalt as Co3+ were noted in the low cobalt ores. High percentage cobalt dissolutions (85% to 95%) were achieved when leaching mixed Co-Cu oxidised ores in the presence of SO2. UV/Visible spectroscopy confirmed concentrations of Co3+ and Co2+ before and after SO2 treatment of mixed Co-Cu oxidised ores. Percentage cobalt dissolutions improved by 10% to 20% in microwave irradiated mixed Co-Cu oxidised ores The presence of iron and copper in leach solutions can limit the dissolution of cobalt from mixed Co-Cu oxidised ores to a certain extent.
- Full Text:
- Authors: Ndalamo, John
- Date: 2009-05-19T07:40:16Z
- Subjects: Cobalt , Leaching
- Type: Thesis
- Identifier: uj:8393 , http://hdl.handle.net/10210/2558
- Description: M.Tech. , Recent studies have explored the capabilities of sulphur dioxide (SO2), a reducing agent that shows great potential to enhance the leaching efficiency of cobalt from mixed Co-Cu oxidized ores. The research study reported in this dissertation was conducted to further explore the efficacy of SO2 as a suitable reagent to improve the cobalt yield in solution from mixed Co-Cu oxidised ores. Four mixed Co-Cu oxidised ores were used in this study; namely, high cobalt ore (34% Co), low cobalt ore with mica (4% Co), low cobalt ore without mica (3% Co) and high copper ore (0.5% Co). The mechanistic leaching pathways of cobalt from these ores with and without SO2 were investigated and monitored using Ultra-Violet/Visible spectroscopy. Mineralogical studies of these ores was carried out by X - ray diffraction (XRD), X - ray fluorescence (XRF) and flame atomic absorption spectroscopy (AAS). Microwave processing of these ores prior to leaching experiments was also investigated. The experimental work was carried out on a laboratory scale and highlights of results obtained are summarized as follows: Although not much information pertaining to Co2+ bearing minerals in mixed Co-Cu oxidised ores was derived from XRD results, two forms of heterogenite minerals (CoOOH-2H and CoOOH-3R), which bear cobalt as Co3+ were noted in the low cobalt ores. High percentage cobalt dissolutions (85% to 95%) were achieved when leaching mixed Co-Cu oxidised ores in the presence of SO2. UV/Visible spectroscopy confirmed concentrations of Co3+ and Co2+ before and after SO2 treatment of mixed Co-Cu oxidised ores. Percentage cobalt dissolutions improved by 10% to 20% in microwave irradiated mixed Co-Cu oxidised ores The presence of iron and copper in leach solutions can limit the dissolution of cobalt from mixed Co-Cu oxidised ores to a certain extent.
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Leaching of Nickel from a Jarosite Precipitate with Hydrochloric Acid
- Nheta, Wilie and Makhatha, Mamookho E.
- Authors: Nheta, Wilie and Makhatha, Mamookho E.
- Date: 2013
- Subjects: Hydrochloric acid , Jarosite precipitate , Leaching , Nickel
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15943 , uj:15721 , Nheta, W. and Makhatha, M.E. 2013. Leaching of Nickel from a Jarosite Precipitate with Hydrochloric Acid. International Conference on Chemical and Environmental Engineering (ICCEE'2013), 15-16 April, 2013, Johannesburg (South Africa).
- Description: Abstract Jarosite precipitates produced at Impala’s Base Metal Refineries contain substantial amounts of nickel. Laboratory-scale experiments were carried out in an attempt to recover nickel by leaching with hydrochloric acid. The leaching efficiency of nickel was 60% at 25oC. The acid concentration of 0.5 – 1 molar, pulp density of 10% and leaching time of 90 min was found to be optimum under the present conditions. High pH could break the jarosite structure and release more iron into the solution which will adversely affect the following precipitation process to recover nickel. 27% of the nickel lost is by entrainment. The reaction is diffusion independent.
- Full Text:
- Authors: Nheta, Wilie and Makhatha, Mamookho E.
- Date: 2013
- Subjects: Hydrochloric acid , Jarosite precipitate , Leaching , Nickel
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15943 , uj:15721 , Nheta, W. and Makhatha, M.E. 2013. Leaching of Nickel from a Jarosite Precipitate with Hydrochloric Acid. International Conference on Chemical and Environmental Engineering (ICCEE'2013), 15-16 April, 2013, Johannesburg (South Africa).
- Description: Abstract Jarosite precipitates produced at Impala’s Base Metal Refineries contain substantial amounts of nickel. Laboratory-scale experiments were carried out in an attempt to recover nickel by leaching with hydrochloric acid. The leaching efficiency of nickel was 60% at 25oC. The acid concentration of 0.5 – 1 molar, pulp density of 10% and leaching time of 90 min was found to be optimum under the present conditions. High pH could break the jarosite structure and release more iron into the solution which will adversely affect the following precipitation process to recover nickel. 27% of the nickel lost is by entrainment. The reaction is diffusion independent.
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Recovery of PGMS from mine sludge by leaching
- Nheta, Willie, Mapotsane, Kutullo
- Authors: Nheta, Willie , Mapotsane, Kutullo
- Date: 2017
- Subjects: Mine sludge , Leaching , Oxidizing agents
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/239288 , uj:24580 , Citation: Nheta, W. & Mapotsane, K. 2017. Recovery of PGMS from mine sludge by leaching.
- Description: Abstract: South Africa host massive deposits of Platinum Group Metals (PGMs) in the Igneous Bushveld Complex. These deposits have been mined for a long time and in the process Mine sludge has been produced. It has been piled up and there is need to recover PGMs locked in it. The conventional way of processing PGMs has proved to be very difficult due to ultra-fines in the sludge that causes major loses during flotation. An alternative hydrometallurgical process for recovery of PGMs from a mine sludge by leaching using a mixture of hydrochloric acid and different oxidizing agents was investigated. It was found that the mine sludge contained 8.93 g/t Pt, 6.99 g/t Pd, 2.79 g/t Ru and minor percentages of Rh, Ir, and Au. It had a particle size distribution (PSD) of 84.64% passing 38 microns. Major mineral phases present are sphalerite, chalcopyrite, pentlandite, covellite, bornite, chromite, and silica as the main gangue. HCL + H2O2 (1:1) combination managed to leach all the PGMs and gold. HCL + Ferric Chloride (1:1) combination managed to leach Pt, Rh and Ru very well but it could not leach Pd. Further investigation on the optimization of the leaching conditions is being done.
- Full Text:
- Authors: Nheta, Willie , Mapotsane, Kutullo
- Date: 2017
- Subjects: Mine sludge , Leaching , Oxidizing agents
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/239288 , uj:24580 , Citation: Nheta, W. & Mapotsane, K. 2017. Recovery of PGMS from mine sludge by leaching.
- Description: Abstract: South Africa host massive deposits of Platinum Group Metals (PGMs) in the Igneous Bushveld Complex. These deposits have been mined for a long time and in the process Mine sludge has been produced. It has been piled up and there is need to recover PGMs locked in it. The conventional way of processing PGMs has proved to be very difficult due to ultra-fines in the sludge that causes major loses during flotation. An alternative hydrometallurgical process for recovery of PGMs from a mine sludge by leaching using a mixture of hydrochloric acid and different oxidizing agents was investigated. It was found that the mine sludge contained 8.93 g/t Pt, 6.99 g/t Pd, 2.79 g/t Ru and minor percentages of Rh, Ir, and Au. It had a particle size distribution (PSD) of 84.64% passing 38 microns. Major mineral phases present are sphalerite, chalcopyrite, pentlandite, covellite, bornite, chromite, and silica as the main gangue. HCL + H2O2 (1:1) combination managed to leach all the PGMs and gold. HCL + Ferric Chloride (1:1) combination managed to leach Pt, Rh and Ru very well but it could not leach Pd. Further investigation on the optimization of the leaching conditions is being done.
- Full Text:
Leaching of nickel from a jarosite precipitate with hydrochloric acid
- Nheta, Willie, Makhatha, Mamookho E.
- Authors: Nheta, Willie , Makhatha, Mamookho E.
- Date: 2013
- Subjects: Hydrochloric acid , Leaching , Nickel , Jarosite precipitates
- Type: Article
- Identifier: uj:4969 , http://hdl.handle.net/10210/13070
- Description: Jarosite precipitates produced at Impala’s Base Metal Refineries contain substantial amounts of nickel. Laboratory-scale experiments were carried out in an attempt to recover nickel by leaching with hydrochloric acid. The leaching efficiency of nickel was 60% at 25oC. The acid concentration of 0.5 – 1 molar, pulp density of 10% and leaching time of 90 min was found to be optimum under the present conditions. High pH could break the jarosite structure and release more iron into the solution which will adversely affect the following precipitation process to recover nickel. 27% of the nickel lost is by entrainment. The reaction is diffusion independent.
- Full Text:
- Authors: Nheta, Willie , Makhatha, Mamookho E.
- Date: 2013
- Subjects: Hydrochloric acid , Leaching , Nickel , Jarosite precipitates
- Type: Article
- Identifier: uj:4969 , http://hdl.handle.net/10210/13070
- Description: Jarosite precipitates produced at Impala’s Base Metal Refineries contain substantial amounts of nickel. Laboratory-scale experiments were carried out in an attempt to recover nickel by leaching with hydrochloric acid. The leaching efficiency of nickel was 60% at 25oC. The acid concentration of 0.5 – 1 molar, pulp density of 10% and leaching time of 90 min was found to be optimum under the present conditions. High pH could break the jarosite structure and release more iron into the solution which will adversely affect the following precipitation process to recover nickel. 27% of the nickel lost is by entrainment. The reaction is diffusion independent.
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Selective leaching of vanadium from vanadium slag using organic acids
- Ntita, J., Nheta, W., Staden, Petrus V.
- Authors: Ntita, J. , Nheta, W. , Staden, Petrus V.
- Date: 2017
- Subjects: Leaching , Organic acids , Slag
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/256874 , uj:26973 , Citation: Ntita, J., Nheta, W. & Staden, Petrus V. 2017. Selective leaching of vanadium from vanadium slag using organic acids.
- Description: Abstract: Large amounts of vanadium bearing slags are produced during steel making and discarded to the environment. Bioleaching has proved that it is an environmentally friendly route which has been lately used for recovery of metals. The leaching of vanadium from a roasted slag was studied using gluconic, citric and oxalic acids. The vanadium slag was roasted at 900oC in presence of Na2CO3 prior to leaching. The effect of acid concentration, solid/liquid ratio, particles size and temperature were investigated. It was observed that at a concentration of 150mM for gluconic acid and 100mM of citric and oxalic acid, 2% of S/L ratio, -38μm and temperature of 45oC, 91, 86 and 81% of vanadium were recovered from gluconic, citric and oxalic acid respectively. Recovery of vanadium using gluconic acid is affected more by the acid concentration compared to citric and oxalic acids. The solid/ liquid ratio as well as the particle size increase have a negative effect on the recovery of each acid and the temperature increase allows to enhance the recovery.
- Full Text:
- Authors: Ntita, J. , Nheta, W. , Staden, Petrus V.
- Date: 2017
- Subjects: Leaching , Organic acids , Slag
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/256874 , uj:26973 , Citation: Ntita, J., Nheta, W. & Staden, Petrus V. 2017. Selective leaching of vanadium from vanadium slag using organic acids.
- Description: Abstract: Large amounts of vanadium bearing slags are produced during steel making and discarded to the environment. Bioleaching has proved that it is an environmentally friendly route which has been lately used for recovery of metals. The leaching of vanadium from a roasted slag was studied using gluconic, citric and oxalic acids. The vanadium slag was roasted at 900oC in presence of Na2CO3 prior to leaching. The effect of acid concentration, solid/liquid ratio, particles size and temperature were investigated. It was observed that at a concentration of 150mM for gluconic acid and 100mM of citric and oxalic acid, 2% of S/L ratio, -38μm and temperature of 45oC, 91, 86 and 81% of vanadium were recovered from gluconic, citric and oxalic acid respectively. Recovery of vanadium using gluconic acid is affected more by the acid concentration compared to citric and oxalic acids. The solid/ liquid ratio as well as the particle size increase have a negative effect on the recovery of each acid and the temperature increase allows to enhance the recovery.
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The effect of leaching time and ammonia concentration on the atmospheric leaching of copper
- Ntuli, Freeman, Muzenda, Edison, Ramatsa, Ishmael, Belaid, Mohamed, Kabuba, John
- Authors: Ntuli, Freeman , Muzenda, Edison , Ramatsa, Ishmael , Belaid, Mohamed , Kabuba, John
- Date: 2013
- Subjects: Ammonia , Cementation , Concentration , Leaching
- Language: English
- Type: Conference
- Identifier: http://hdl.handle.net/10210/17348 , uj:15872 , F. Ntuli, E. et al. 2013. The effect of leaching time and ammonia concentration on the atmospheric leaching of copper. 2nd International Conference on Chemistry and Chemical Engineering, IPCBEE vol.14, Singapore 2011. Cited by: KG Tshilombo, AF Mulaba-Bafubiandi - Magnesium, 2013 - psrcentre.org
- Description: Abstract: Please refer to full text for abstract.
- Full Text:
- Authors: Ntuli, Freeman , Muzenda, Edison , Ramatsa, Ishmael , Belaid, Mohamed , Kabuba, John
- Date: 2013
- Subjects: Ammonia , Cementation , Concentration , Leaching
- Language: English
- Type: Conference
- Identifier: http://hdl.handle.net/10210/17348 , uj:15872 , F. Ntuli, E. et al. 2013. The effect of leaching time and ammonia concentration on the atmospheric leaching of copper. 2nd International Conference on Chemistry and Chemical Engineering, IPCBEE vol.14, Singapore 2011. Cited by: KG Tshilombo, AF Mulaba-Bafubiandi - Magnesium, 2013 - psrcentre.org
- Description: Abstract: Please refer to full text for abstract.
- Full Text:
The effect of leaching time and ammonia concentration on the atmospheric leaching of copper
- Ntuli, Freeman, Muzenda, Edison, Ramatsa, Ishmael, Belaid, Mohamed, Kabuba, John
- Authors: Ntuli, Freeman , Muzenda, Edison , Ramatsa, Ishmael , Belaid, Mohamed , Kabuba, John
- Date: 2011
- Subjects: Copper recovery , Leaching , Ammonia concentrations
- Type: Article
- Identifier: uj:5319 , ISSN 2010-4618 , http://hdl.handle.net/10210/8195
- Description: The effects of ammonia concentration and leaching time were investigated to determine the optimum leaching conditions. The experiments were conducted in a leaching cell submerged in a water bath, with ammonia concentrations of 1.5 M, 2.0 M, 2.5 M and 3.0 M and varying leaching time from 0 to 300 min. Ni-Cu matte containing 23% by mass Cu was used in this experimental study. Increase in the concentration of the lixiviant was found to increase recovery when leaching for 130 minutes, with a recovery of 32.86% Cu using 3 M solution of ammonia. An increase in the leaching time resulted in more copper being leached for all lixiviant concentrations. However, leaching with 2 M ammonia solution gave a higher yield of copper compared to higher concentrations. This anomaly could be a result of cementation; Cu is displaced by Ni as Ni is a more electronegative metal than Cu .It was found that at higher concentrations more nickel was extracted.
- Full Text:
- Authors: Ntuli, Freeman , Muzenda, Edison , Ramatsa, Ishmael , Belaid, Mohamed , Kabuba, John
- Date: 2011
- Subjects: Copper recovery , Leaching , Ammonia concentrations
- Type: Article
- Identifier: uj:5319 , ISSN 2010-4618 , http://hdl.handle.net/10210/8195
- Description: The effects of ammonia concentration and leaching time were investigated to determine the optimum leaching conditions. The experiments were conducted in a leaching cell submerged in a water bath, with ammonia concentrations of 1.5 M, 2.0 M, 2.5 M and 3.0 M and varying leaching time from 0 to 300 min. Ni-Cu matte containing 23% by mass Cu was used in this experimental study. Increase in the concentration of the lixiviant was found to increase recovery when leaching for 130 minutes, with a recovery of 32.86% Cu using 3 M solution of ammonia. An increase in the leaching time resulted in more copper being leached for all lixiviant concentrations. However, leaching with 2 M ammonia solution gave a higher yield of copper compared to higher concentrations. This anomaly could be a result of cementation; Cu is displaced by Ni as Ni is a more electronegative metal than Cu .It was found that at higher concentrations more nickel was extracted.
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Characterization of South African waste foundry molding sand : metallic contaminants
- Nyembwe, J. K., Makhatha, Mamookho E., Madzivhandila, T ., Nyembwe, K. D.
- Authors: Nyembwe, J. K. , Makhatha, Mamookho E. , Madzivhandila, T . , Nyembwe, K. D.
- Date: 2015-07-20
- Subjects: Foundry waste , Leaching , Hazardous wastes
- Type: Article
- Identifier: uj:5173 , http://hdl.handle.net/10210/14414
- Description: Waste foundry sands are invariably contaminated to some extent during the manufacturing of cast alloys. As such the sand is regarded as a hazardous material that requires exceptional precautions for its disposal. Therefore, the study is initiated to identify, quantify and to classify metallic contaminants present in these sands. To achieve these objectives in conjunction with the South African Waste Management Act which plays as the guideline for industrial waste disposal, samples were collected from various South African foundries. In the present study, ten waste sand samples were characterised using XRF, XRD, SEM-EDS and Sulphur analyser. It was found after comparison with a virgin sand used as control or reference sand, that the cast alloy and the moulding additives are the main pollutants present in the waste foundry sand. The additional sulphur and acid potential characterisation, showed that the waste foundry sand has a low potential for sulphuric acid and acid sulphate soil formation when submerged in aquatic medium. The leaching behaviour and the total metallic concentration of the waste was similar to the virgin soil thus their similar classification in the same waste class category.
- Full Text:
- Authors: Nyembwe, J. K. , Makhatha, Mamookho E. , Madzivhandila, T . , Nyembwe, K. D.
- Date: 2015-07-20
- Subjects: Foundry waste , Leaching , Hazardous wastes
- Type: Article
- Identifier: uj:5173 , http://hdl.handle.net/10210/14414
- Description: Waste foundry sands are invariably contaminated to some extent during the manufacturing of cast alloys. As such the sand is regarded as a hazardous material that requires exceptional precautions for its disposal. Therefore, the study is initiated to identify, quantify and to classify metallic contaminants present in these sands. To achieve these objectives in conjunction with the South African Waste Management Act which plays as the guideline for industrial waste disposal, samples were collected from various South African foundries. In the present study, ten waste sand samples were characterised using XRF, XRD, SEM-EDS and Sulphur analyser. It was found after comparison with a virgin sand used as control or reference sand, that the cast alloy and the moulding additives are the main pollutants present in the waste foundry sand. The additional sulphur and acid potential characterisation, showed that the waste foundry sand has a low potential for sulphuric acid and acid sulphate soil formation when submerged in aquatic medium. The leaching behaviour and the total metallic concentration of the waste was similar to the virgin soil thus their similar classification in the same waste class category.
- Full Text: