Browsing Research Output by Author "Bunt, J.R."
Now showing items 1-20 of 41
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Behaviour of selected major elements during fixed-bed gasification of South African bituminous coal
Bunt, J.R.; Waanders, F.B.; Schobert, H. (Elsevier, 2012)The Sasol–Lurgi Fixed Bed Dry Bottom gasifier (S–L FBDB) treats a feed coal containing c.a. 30% ash forming minerals, which means that there are complex mineralogical processes occurring simultaneously with each other, ... -
Carbon particle type characterization of the carbon behaviour impacting on a commercial-scale Sasol-Lurgi FBDB gasifier
Bunt, J.R.; Waanders, F.B.; Wagner, N.J. (Elsevier, 2009)Char-form analysis, whilst not yet an ISO standard, is a relatively common characterization method applied to pulverized coal samples used by power utilities globally. Fixed-bed gasification coal feeds differ from pulverized ... -
Changes to the organic functional groups of an inertinite rich medium rank bituminous coal during acid treatment processes
Strydom, C.A.; Bunt, J.R.; Schobert, H.H.; Raghoo, M. (Elsevier, 2011)A South African inertinite rich medium rank bituminous coal was subjected to a series of acid treatment steps using concentrations of HF and HNO3 ranging between 1.5 and 4 M, temperatures between 65 and 80 °C and reaction ... -
Co-pyrolysis of coal and raw/torrefied biomass: a review on chemistry, kinetics and implementation
Gouws, S.M.; Bunt, J.R.; Neomagus, H.W.J.P.; Carrier, M. (Elsevier, 2021)Thermochemical conversion via co-pyrolysis has the potential to be an efficient route for converting biomass to bio-energy and bio-refinery products. In this review, the implementation of co-pyrolysis of torrefied biomass ... -
CO2 reactivity of briquettes derived from discard inertinite-rich Highveld coal using lignosulphonate and resin as binders
Leokaoke, N.T.; Bunt, J.R.; Neomagus, H.W.J.P.; Waanders, F.B.; Strydom, C.A. (SAIMM, 2019)South African collieries generate approximately 31 Mt of fine and ultrafine coal annually, with the majority of the ultrafine fraction discarded in slurry ponds and underground workings. Use can be made of this energy ... -
Coal char temperature profile estimation using optical reflectance for a commercial-scale Sasol-Lurgi FBDB gasifier
Bunt, J.R.; Waanders, F.B.; Joubert, J.P. (Elsevier, 2008)In the Sasol-Lurgi fixed-bed dry-bottom (FBDB) gasifier the temperature in the combustion zone should not exceed the melting point of the ash-forming minerals, causing them to melt/flow and agglomerate. Sintering of ash ... -
Coal reactivity and selection for solid-based pre-reduction of sponge iron
Van Wyk, S.; Neomagus, H.W.J.P.; Bunt, J.R.; Everson, R.C. (Taylor & Francis, 2020)Solid-based direct reduction of iron ore requires the reductant coal to have a suitable CO2 reactivity to achieve optimum pre-reduction within a rotary kiln. The CO2 reactivity is affected by numerous factors including ... -
Damring formation during rotary kiln chromite pre-reduction: effects of pulverized carbonaceous fuel selection and partial pellet melting
Van Staden, Y.; Beukes, J.P.; Van Zyl, P.G.; Kleynhans, E.L.J.; Bunt, J.R. (Springer, 2018)Electricity consumption is the largest cost contributing factor in the production of ferrochrome. Currently the pelletized chromite pre-reduction process (solid-state reduction of chromite) is the process option with the ... -
Destabilization dynamics of clay and acid-free polymers of ferric and magnesium salts in AMD without pH adjustment
Ntwampe, I.O.; Waanders, F.B.; Bunt, J.R. (IWA Publishing, 2016)The physicochemical treatment was employed to treat acid mine drainage (AMD) in the removal of turbid materials using clay only (exp A) and a combination of clay, FeCl3 and Mg(OH)2 (exp B) to form a polymer. A 5 g sample ... -
Direct liquefaction of 2 South African bituminous coal fines and their beneficiated float fractions
Uwaoma, R.C.; Strydom, C.A.; Matjie, R.H.; Bunt, J.R. (EARET, 2018)The direct liquefaction of South African coal fines and their density separated (float) fractions were carried out under moderate conditions in a laboratory autoclave. The liquefaction temperature ranged between 380 and ... -
The effect of carbonaceous reductant selection on chromite pre-reduction
Kleynhans, E.L.J.; Beukes, J.P.; Van Zyl, P.G.; Bunt, J.R.; Venter, M. (Springer, 2017)Ferrochrome (FeCr) production is an energy-intensive process. Currently, the pelletized chromite pre-reduction process, also referred to as solid-state reduction of chromite, is most likely the FeCr production process ... -
Green coal development for application in fixed-bed catalytic gasification
Bunt, J.R.; Marx, S.; Waanders, F.B.; Leokaoke, N.T. (SAIMM, 2018)A novel ‘green coal’ product formulation has recently been developed and the utilization concept tested at the North-West University coal research laboratories. Hydrothermal liquefaction was used to produce bio-oil ... -
Identification of reaction zones in a commercial Sasol-Lurgi fixed bed dry bottom gasifier operating on North Dakota lignite
Mangena, S.J.; Waanders, F.B.; Bunt, J.R.; Baker, G. (Elsevier, 2011)The Sasol-Lurgi fixed bed dry bottom gasification technology has the biggest market share in the world with 101 gasifiers in operation. To be able to further improve the technology and also to optimise the operating plants, ... -
Identification of the reaction zones occurring in a commercial-scale Sasol-Lurgie FBDB gasifier
Bunt, J.R.; Waanders, F.B. (Elsevier, 2008)Gasification behaviour is particle dependent, whilst gasifier (reactor) behaviour is an averaging process of individual responses of each particle. It was hypothesized, that if it were possible to extract and analyze ... -
The impact of particle size and maceral segregation on char formation in a packed bed combustion unit
Malumbazo, N.; Wagner, N.J.; Bunt, J.R. (ELSEVIER, 2013)Highveld parent coal was crushed into three size fractions, namely: 5 mm–75 mm, 5 mm–53 mm, and 5–37.5 mm. The crushed samples were subjected as feed coals to heating in a packed-bed reactor to investigate the influence ... -
Influence of added potassium and sodium carbonates on CO2 reactivity of the char from a demineralized inertinite rich bituminous coal
Klopper, L.; Strydom, C.A.; Bunt, J.R. (Elsevier, 2012)The addition of K2CO3, Na2CO3 and a mixture of the two catalysts showed an increase in the CO2 reactivity of the char prepared from the demineralized inertinite rich bitumious coal at 900 °C in nitrogen. The CO2 reactivity ... -
Influence of additives on the devolatilization product yield of typical South African coals, and effect on tar composition
Bean, N.C.; Bunt, J.R.; Strydom, C.A.; Neomagus, H.W.J.P.; Van Niekerk, D. (SAIMM, 2018)South African coal is mainly used for electricity generation by means of pulverized fuel combustion and liquid fuels production via indirect gasification technology and Fischer-Tropsch synthesis. In order to expand the ... -
The influence of calcium lignosulphonate addition on non-isothermal pyrolysis and gasification of demineralised bituminous coal fines
Uwaoma, R.C.; Seheri, M.P.; Strydom, C.A.; Bunt, J.R.; Matjie, R.H. (Elsevier BV, 2022)Amorphous calcium lignosulphonate (CaLS), a by-product of the paper industry, was evaluated as an adhesive to bind demineralised bituminous coal fines in various weight percentage ratios. Sequential acid (HCl, HF, ... -
The influence of selected biomass additions on the co-pyrolysis with an inertinite-rich medium rank C grade South African coal
Strydom, C.A.; Sehume, T.Z.; Bunt, J.R.; Van Dyk, J.C. (SAIMM, 2015)Co-pyrolysis of four biomass samples (hardwood chip, softwood chip, pinewood chip, and sugarcane bagasse) with an inertinite-rich medium rank C South African coal was investigated. Proximate and ultimate analyses of the ... -
The influence of the roof and floor geological structures on the ash composition produced from coal at UCG temperatures
Uwaoma, R.C.; Strydom, C.A.; Matjie, R.H.; Bunt, J.R.; Van Dyk, J.C. (Taylor & Francis, 2020)The mineralogy of the ash and slag formed at typical UCG temperatures were investigated using a bituminous coal from the Theunissen UCG site in the Free State province of South Africa. The ash and slag samples were produced ...