The aim of this study was to determine the structural, compositional, and mineralogical composition of carbonatitic copper sulfide concentrator plant streams. Three samples, each from a different stream(run of mine(RO...The aim of this study was to determine the structural, compositional, and mineralogical composition of carbonatitic copper sulfide concentrator plant streams. Three samples, each from a different stream(run of mine(ROM), concentrate, and tailings) of a copper concentrator were characterized using various techniques, including stereomicroscopy, X-ray fluorescence, X-ray diffraction, Fourier transform infrared(FTIR) spectroscopy, scanning electron microscopy(SEM) in conjunction with energy-dispersive X-ray spectroscopy(EDS), and optical microscopy. The results reveal that each stream possesses its own unique compositional features. Carbonate minerals associated with calcite and dolomite, followed by quartz, remain the major minerals in both the ROM and tails streams. In the ROM stream, chalcopyrite appears to occur as veins within the carbonatite-hosting ore body. Mineral phase mutation was discovered in the tails stream because magnetite formerly identified in the ROM as the primary iron oxide had evolved into hematite. This metamorphosis was likely promoted by the concentration process. The concentration process was effective, upgrading the chalcopyrite content from 2 wt% in the ROM stream to 58 wt% in the concentrate stream; it was accompanied by bornite(4 wt%), anilite(3 wt%), and digenite(2.5 wt%). In addition, the concentrate stream exhibited properties distinctive from those of the other streams. The FTIR analysis showed the existence of a sulfide group related to the chalcopyrite mineral. Free chalcopyrite grains were observed in the concentrate by SEM analysis, and their mineral presence was supported by the EDS analysis results. All characterization techniques corresponded well with each other regarding the structure, chemistry, and composition of the samples.展开更多
The dissolution of a carbonatitic chalcopyrite(CuFeS2)was studied in H_(2)SO_(4)−Fe_(2)(SO_(4))_(3)−FeSO_(4)−H_(2)O at varying pH values(0.5−2.5)and 25℃ for 12 h.Experiments were conducted with a size fraction of 53...The dissolution of a carbonatitic chalcopyrite(CuFeS2)was studied in H_(2)SO_(4)−Fe_(2)(SO_(4))_(3)−FeSO_(4)−H_(2)O at varying pH values(0.5−2.5)and 25℃ for 12 h.Experiments were conducted with a size fraction of 53−75μm.Low Cu recoveries,below 15%,were observed in all pH regimes.The results from the XRD,SEM−EDS,and optical microscopic(OM)analyses of the residues indicated that the dissolution proceeded through the formation of transient phases.Cu_(3.39)Fe_(0.61)S_(4) and Cu_(2)S were the intermediate phases at pH 0.5 and 1.0,respectively,whereas Cu_(5)FeS_(4) was the major mineral at pH 1.5 and 1.8.The thermodynamic modelling predicted the sequential formation of CuFeS_(2)→Cu_(5)FeS_(4)→Cu_(2)S→CuS.The soluble intermediates were Cu_(5)FeS_(4) and Cu2S,whilst,CuS and Cu_(3.39)Fe_(0.61)S_(4) were the refractory phases,supporting their cumulating behaviour throughout the dissolution.The obtained results suggest that the formation of CuS and Cu_(3.39)Fe_(0.61)S_(4) could contribute to the passive film formed during CuFeS_(2) leaching.展开更多
For low-income communities in South Africa,coal is the most common solid fuel which is burnt in a variety of devices,including imbaulas and cast-iron stoves.The present work was conducted with the aim of determining t...For low-income communities in South Africa,coal is the most common solid fuel which is burnt in a variety of devices,including imbaulas and cast-iron stoves.The present work was conducted with the aim of determining the effect of the fuel particle size on the performance of coal,typically sourced in low-income households in townships in South Africa,and to subsequently compare the performance with a feed char of a common cast iron stove.Four fuel particle sizes of 15,20,30,and 40 mm,as well as a composite of the sizes were tested at 550C,against their untreated coal analogues to evaluate the thermal performance of each fuel.The thermal performance assessment metrics are ignition time,water boiling time,heat transfer and combustion efficiencies,while CO and CO_(2)emissions were measured for the calculations of CO/CO_(2)ratios.Ignition times were found to decrease from coals to chars and to decrease with increasing particle size.The effects of fuel type on the water boiling time were only observed in the later stages of the burn cycle,with the char boiling a 2 L batch of water in an average 24 min,while the coals reported an average boiling time of 20 min.Heat transfer efficiencies showed no significant variation with fuel type or particle size,with the average efficiency for the coals and that of the chars being around 66%.The fuels’performance was better gauged by the combustion efficiency,which was found to improve marginally from the coal fuels to the chars,and to increase with increasing particle size.Results from this testwork could contribute to the performance inventories from the combustion of domestic coal mined in South Africa in a typical cast iron stove which is used in informal settlements.展开更多
The coal combustion in cast-iron stoves leads to health hazards and air pollution.In this study the CO,SO2,NOx,PM and VOC emission concentrations were measured whilst combusting four fuel particle sizes(15,20,30,and 4...The coal combustion in cast-iron stoves leads to health hazards and air pollution.In this study the CO,SO2,NOx,PM and VOC emission concentrations were measured whilst combusting four fuel particle sizes(15,20,30,and 40 mm)as well as a composite of the sizes(all pre-devolatilized at a temperature of 550C)in a cast-iron stove.The results were compared to their raw coal analogues to evaluate the emission performance of each fuel type.Emission factors for NOx and SO2 were found to depend on the fuel nitrogen and sulphur contents in the coal and the combustion conditions used during pyrolysis.The PM,SO2 and VOC emissions show a strong dependence on the ash percentage and volatile matter yields,which both increased with increasing particle size.In addition,the PM,SO2 and VOC missions were found to only depend on particle size on a mechanistic level.The VOCs and PM emission factors are inversely correlated with particle size.The results from this study offer insight into the combustion environment in the Falkirk Union No 7 cast-iron stove as well as how this environment applies to low smoke fuels.The work contributes to the emission and performance inventories from South African domestic coal combustion in this stove used in informal settlements.展开更多
基金the North-West University (IREA Account) and the University of South Africa (CSET Special Research Fund) for the support and promotion of this research
基金the chemical engineering department at the North-West University for the support
文摘The aim of this study was to determine the structural, compositional, and mineralogical composition of carbonatitic copper sulfide concentrator plant streams. Three samples, each from a different stream(run of mine(ROM), concentrate, and tailings) of a copper concentrator were characterized using various techniques, including stereomicroscopy, X-ray fluorescence, X-ray diffraction, Fourier transform infrared(FTIR) spectroscopy, scanning electron microscopy(SEM) in conjunction with energy-dispersive X-ray spectroscopy(EDS), and optical microscopy. The results reveal that each stream possesses its own unique compositional features. Carbonate minerals associated with calcite and dolomite, followed by quartz, remain the major minerals in both the ROM and tails streams. In the ROM stream, chalcopyrite appears to occur as veins within the carbonatite-hosting ore body. Mineral phase mutation was discovered in the tails stream because magnetite formerly identified in the ROM as the primary iron oxide had evolved into hematite. This metamorphosis was likely promoted by the concentration process. The concentration process was effective, upgrading the chalcopyrite content from 2 wt% in the ROM stream to 58 wt% in the concentrate stream; it was accompanied by bornite(4 wt%), anilite(3 wt%), and digenite(2.5 wt%). In addition, the concentrate stream exhibited properties distinctive from those of the other streams. The FTIR analysis showed the existence of a sulfide group related to the chalcopyrite mineral. Free chalcopyrite grains were observed in the concentrate by SEM analysis, and their mineral presence was supported by the EDS analysis results. All characterization techniques corresponded well with each other regarding the structure, chemistry, and composition of the samples.
基金the Extraction Metallurgy Laboratory at the University of Johannesburg for equipment utilizationthe Department of Chemical Engineering at the North-West University for the support and promotion of this research.NSERC-DG, CFI, Public Works and Government Service, Canada (formally Devco arm of ECBC), the Industrial Research Chair of Mine Water Management at CBU, ACOA and IRAP grants
文摘The dissolution of a carbonatitic chalcopyrite(CuFeS2)was studied in H_(2)SO_(4)−Fe_(2)(SO_(4))_(3)−FeSO_(4)−H_(2)O at varying pH values(0.5−2.5)and 25℃ for 12 h.Experiments were conducted with a size fraction of 53−75μm.Low Cu recoveries,below 15%,were observed in all pH regimes.The results from the XRD,SEM−EDS,and optical microscopic(OM)analyses of the residues indicated that the dissolution proceeded through the formation of transient phases.Cu_(3.39)Fe_(0.61)S_(4) and Cu_(2)S were the intermediate phases at pH 0.5 and 1.0,respectively,whereas Cu_(5)FeS_(4) was the major mineral at pH 1.5 and 1.8.The thermodynamic modelling predicted the sequential formation of CuFeS_(2)→Cu_(5)FeS_(4)→Cu_(2)S→CuS.The soluble intermediates were Cu_(5)FeS_(4) and Cu2S,whilst,CuS and Cu_(3.39)Fe_(0.61)S_(4) were the refractory phases,supporting their cumulating behaviour throughout the dissolution.The obtained results suggest that the formation of CuS and Cu_(3.39)Fe_(0.61)S_(4) could contribute to the passive film formed during CuFeS_(2) leaching.
基金acknowledge the DS&T and NRF(Coal Research Chair Grant Nos.86880)of SA for financing this investigation.
文摘For low-income communities in South Africa,coal is the most common solid fuel which is burnt in a variety of devices,including imbaulas and cast-iron stoves.The present work was conducted with the aim of determining the effect of the fuel particle size on the performance of coal,typically sourced in low-income households in townships in South Africa,and to subsequently compare the performance with a feed char of a common cast iron stove.Four fuel particle sizes of 15,20,30,and 40 mm,as well as a composite of the sizes were tested at 550C,against their untreated coal analogues to evaluate the thermal performance of each fuel.The thermal performance assessment metrics are ignition time,water boiling time,heat transfer and combustion efficiencies,while CO and CO_(2)emissions were measured for the calculations of CO/CO_(2)ratios.Ignition times were found to decrease from coals to chars and to decrease with increasing particle size.The effects of fuel type on the water boiling time were only observed in the later stages of the burn cycle,with the char boiling a 2 L batch of water in an average 24 min,while the coals reported an average boiling time of 20 min.Heat transfer efficiencies showed no significant variation with fuel type or particle size,with the average efficiency for the coals and that of the chars being around 66%.The fuels’performance was better gauged by the combustion efficiency,which was found to improve marginally from the coal fuels to the chars,and to increase with increasing particle size.Results from this testwork could contribute to the performance inventories from the combustion of domestic coal mined in South Africa in a typical cast iron stove which is used in informal settlements.
基金the DS&T and NRF of SA(Coal Research Chair Grant No.86880)for funding this project.
文摘The coal combustion in cast-iron stoves leads to health hazards and air pollution.In this study the CO,SO2,NOx,PM and VOC emission concentrations were measured whilst combusting four fuel particle sizes(15,20,30,and 40 mm)as well as a composite of the sizes(all pre-devolatilized at a temperature of 550C)in a cast-iron stove.The results were compared to their raw coal analogues to evaluate the emission performance of each fuel type.Emission factors for NOx and SO2 were found to depend on the fuel nitrogen and sulphur contents in the coal and the combustion conditions used during pyrolysis.The PM,SO2 and VOC emissions show a strong dependence on the ash percentage and volatile matter yields,which both increased with increasing particle size.In addition,the PM,SO2 and VOC missions were found to only depend on particle size on a mechanistic level.The VOCs and PM emission factors are inversely correlated with particle size.The results from this study offer insight into the combustion environment in the Falkirk Union No 7 cast-iron stove as well as how this environment applies to low smoke fuels.The work contributes to the emission and performance inventories from South African domestic coal combustion in this stove used in informal settlements.
