Browsing Research Output by Author "Bunt, John R."
Now showing items 1-20 of 33
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Assessing the catalytic effect of coal ash constituents on the CO2 gasification rate of high ash, South African coal
Hattingh, Burgert B.; Everson, Raymond C.; Neomagus, Hein W.J.P.; Bunt, John R. (Elsevier, 2011)The catalytic effect of inorganic species, within the ash, on the CO2 gasification of three South African coals containing similar carbon-structural properties (elemental, structural and petrographical properties) was ... -
Bio-oil production from sweet sorghum bagasse via liquefaction using alkaline solutions and identification of phenolic products
Sehume, Thabo Z.; Strydom, Christien A.; Bunt, John R.; Schobert, Harold H. (Springer, 2020)The feasibility of converting biomass into bio-oil and the effect of an alkaline treatment during biomass liquefaction was studied. Sweet sorghum bagasse (SSB) was treated with NaOH concentrations of 0.5, 1.0, 3.0 and 6.0 ... -
The carbon dioxide gasification characteristics of biomass char samples and their effect on coal gasification reactivity during co-gasification
Mafu, Lihle D.; Neomagus, Hein W.J.P.; Everson, Raymond C.; Strydom, Christien A.; Bunt, John R. (Elsevier, 2018)The carbon dioxide gasification characteristics of three biomass char samples and bituminous coal char were investigated in a thermogravimetric analyser in the temperature range of 850–950 °C. Char SB exhibited higher ... -
The carbon dioxide, methane and nitrogen high-pressure sorption properties of South African bituminous coals
Okolo, Gregory N.; Everson, Raymond C.; Neomagus, Hein W.J.P.; Bunt, John R.; Sakurovs, Richard (Elsevier, 2019)In this paper, we report the CO2, CH4 and N2 sorption isotherms of four dry South African bituminous coals at pressures up to 16 MPa at 55 °C. The sorption capacities of the samples with respect to the adsorbate gases ... -
Chemical and physical characterization of spent coffee ground biochar treated by a wet oxidation method for the production of a coke substitute
Maree, Zelma; Strydom, Christien A.; Bunt, John R. (Elsevier, 2020)Coke production relies on the availability, cost and quality of coking coal. Depleting coking coal resources and environmental pressure force the metallurgical industry to search for alternative methods to produce coke. ... -
Chemical and structural characterization of char development during lignocellulosic biomass pyrolysis
Mafu, Lihle D.; Neomagus, Hein W.J.P.; Everson, Raymond C.; Strydom, Christien A.; Okolo, Gregory N.; Bunt, John R. (Elsevier, 2017)The chemical and structural changes of three lignocellulosic biomass samples during pyrolysis were investigated using both conventional and advanced characterization techniques. The use of ATR-FTIR as a characterization ... -
Chemical–structural properties of South African bituminous coals: insights from wide angle XRD–carbon fraction analysis, ATR–FTIR, solid state 13C NMR, and HRTEM techniques
Okolo, Gregory N.; Neomagus, Hein W.J.P.; Everson, Raymond C.; Roberts, Mokone J.; Bunt, John R. (Elsevier, 2015)The chemical–structural properties of four South African bituminous coals were investigated using wide angle X-ray diffraction–carbon fraction analysis (WAXRD–CFA), attenuated total reflection Fourier transform infra-red ... -
Coal particle and bed physical transformational behaviour after thermochemical conversion in a fixed bed
Conradie, Frederik H.; Bunt, John R.; Waanders, Frans B. (Elsevier, 2016)This paper examines the physical transformational behaviour that coal particles and the bed structure undergo in a fixed bed reactor. The transient overfeed configuration is used with feed gas entering from the bottom of ... -
Coal particle chemical transformational behaviour after thermochemical conversion in a fixed bed
Conradie, Frederik H.; Bunt, John R.; Waanders, Frans B. (Elsevier, 2016)This paper examines the chemical transformational behaviour that coal particles undergo during conversion in deep packed beds, typically found in industrial combustion and gasification operations. Experiments were performed ... -
Coal-derived low smoke fuel assessment through coal stove combustion testing
Kühn, Thys; Bunt, John R.; Neomagus, Hein W.J.P.; Piketh, Stuart J.; Everson, Raymond C.; Coetzee, Sansha (Elsevier, 2017)A study was undertaken to investigate the production of low smoke fuel from coal currently used in low-income households in South Africa. Pyrolysis of large coal lumps was studied as a possible production method, and an ... -
Comparison of sintering and compressive strength tendencies of a model coal mineral mixture heat-treated in inert and oxidizing atmospheres
Nel, Marika V.; Strydom, Christien A.; Schobert, Harold H.; Beukes, J. Paul; Bunt, John R. (Elsevier, 2011)The chemical interactions responsible for sintering in a coal mineral mixture were investigated in air and in N2. A mineral mixture was made up by mixing kaolin, pyrite, quartz, calcite, hydromagnesite, FeCO3 and anatase ... -
Dataset on the carbon dioxide, methane and nitrogen high-pressure sorption properties of South African bituminous coals
Okolo, Gregory N.; Everson, Raymond C.; Neomagus, Hein W.J.P.; Bunt, John R.; Sakurovs, Richard (Elsevier, 2019)The dataset presented in this article supplements the result and information published in the report “The carbon dioxide, methane and nitrogen high-pressure sorption properties of South African bituminous coals” (Okolo et ... -
Detailed characterization of SA high mineral matter inertinite–rich coals and density fractions and effect on reaction rates with carbon dioxide: macerals, microlithotypes, carbominerites and minerals
Everson, Raymond C.; Koekemoer, Andrei; Bunt, John R.; Neomagus, Hein W.J.P.; Schwarz, Christopher (SAIChE, 2013)An investigation was undertaken to determine the distribution of macerals and minerals in South African Highveld coal deposits as well as density fractions derived from a typical deposit. The corresponding effects on ... -
The effect of carbon dioxide partial pressure on the gasification rate and pore development of Highveld coal chars at elevated pressures
Gouws, Saartjie M.; Neomagus, Hein W.J.P.; Bunt, John R.; Everson, Ray C.; Roberts, Daniel G. (Elsevier, 2018)Char structural changes occurring during gasification are normally only related to conversion and few data is published on the effect of carbon dioxide partial pressure on the extent of pore development. In this study, the ... -
Effect of sodium compounds on the sintering propensity of coal-associated minerals
Nel, Marika V.; Strydom, Christien A.; Schobert, Harold H.; Beukes, J. Paul; Bunt, John R. (Elsevier, 2015)This study focused on the chemistry involved in sintering of coal-associated minerals during combustion and inert conditions. Changes in mechanical strength were recorded with compressive strength measurements. This method ... -
Elucidation of the structural and molecular properties of typical South African coals
Hattingh, Burgert B.; Everson, Raymond C.; Neomagus, Hein W.J.P.; Bunt, John R.; Van Niekerk, Daniel; Jordaan, Johan H.L.; Mathews, Jonathan P. (ACS, 2013)Advanced analytical techniques were performed on four South African coals, three noncoking and one coking, containing different maceral contributions (vitrinite contents ranging between 24 and 66 vol %, m.m.f.b.). ... -
Evaluating the performance and emission reductions of a coal-derived low-smoke fuel in a conventional household stove
Sumbane, Lungile P.; Piketh, Stuart J.; Bunt, John R.; Neomagus, Hein W.J.P. (IEEE, 2017)A low-smoke fuel (LSF) produced via the devolatilisation of coal lumps is proposed as an option to combat the health-damaging effects of domestic coal combustion. This study investigates the effect of the LSF particle size ... -
Evaluation and prediction of slow pyrolysis products derived from coals of different rank
Pretorius, Gustav N.; Bunt, John R.; Neomagus, Hein; Waanders, Frans B.; Everson, Ray C.; Strydom, Christien A. (Elsevier, 2017)When coal is heated slowly (<10 °C/min), as in the Lurgi Fixed Bed Dry Bottom (FBDB) gasification process, products formed in the pyrolysis region of the gasifier include gas liquor, condensable tar, oil and non-condensable ... -
Evaluation of mineral matter transformations in low-temperature ashes of South African coal feedstock samples and their density separated cuts using high-temperature X-ray diffraction
Rautenbach, Rudelle; Matjie, Ratale H.; Strydom, Christien A.; Bunt, John R.; Ward, Colin R. (Taylor & Francis, 2020)Coal mineral matter is the leading cause of inevitable ash problems (fouling and slagging) during the combustion of coal. Low-temperature ash (LTA) samples of feed coals and the density separated fractions were subjected ... -
Improved reactivity of large coal particles by K2CO3 addition during steam gasification
Coetzee, Sansha; Neomagus, Hein W.J.P.; Bunt, John R.; Everson, Raymond C. (Elsevier, 2013)In this study, the excess solution impregnation method was used to impregnate large coal particles (5 and 10 mm) with K2CO3, and the effect of the additive on steam gasification reactivity was investigated. A washed bituminous, ...