Browsing Faculty of Natural and Agricultural Sciences by Author "Bunt, John R."
Now showing items 1-18 of 18
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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 ... -
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 ... -
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 ... -
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 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 ... -
Mineralogy and petrology of chars produced by South African caking coals and density-separated fractions during pyrolysis and their effects on caking propensity
Tsemane, Mosele M.; Matjie, Ratale H.; Bunt, John R.; Neomagus, Hein W.J.P.; Strydom, Christien A.; Waanders, Frans B.; Uwaoma, Romanus (ACS, 2019)Thermochemical processes use low-rank bituminous coal to produce steam and synthetic gas. Caking coal particles can soften, swell, and coalesce in the South African boilers and fixed-bed gasifiers during pyrolysis and have ... -
Mineralogy of furnace deposits produced by South African coals during pulverized-fuel combustion tests
Matjie, Ratale H.; Bunt, John R.; Strydom, Christien A.; Li, Zhongsheng; Ward, Colin R. (ACS, 2015)Pilot-scale combustion tests were carried out on coals with low (13.5%) and high (39.6%) ash percentages from the Highveld Coalfield of South Africa, using the ALS-ACIRL 100–200 kW Combustion Test Facility. The mineral ... -
Reducing atmosphere ash fusion temperatures of amixture of coal-associated minerals: the effect of inorganic additives and ashing temperature
Nel, Marika V.; Strydom, Christien A.; Schobert, Harold H.; Beukes, J. Paul; Bunt, John R. (Elsevier, 2014)The influence of the ashing temperature and inorganic additives on the reducing-atmosphere ash fusion temperatures of a mixture of coal-associated minerals was investigated. Different inorganic compounds were added to the ... -
Significance of coal properties on the caking degree of coarse coal particles mined at Limpopo Province, Republic of South Africa
Tsemane, Mosele M.; Matjie, Ratale H.; Bunt, John R.; Neomagus, Hein W.J.P.; Strydom, Christien A.; Waanders, Frans B. (Taylor and Francis, 2020)In this paper, a comprehensive coal property (chemical, mineralogical, physical, and petrographic) study was conducted using a caking coal from South Africa, density cuts and pyrolyzed samples to understand the % coal ... -
Solvent extraction of a South African bituminous coal using a model biomass-derived phenolic mixture
Sehume, Thabo Z.; Strydom, Christien A.; Bunt, John R.; Schobert, Harold H. (SACI, 2019)A model biomass-derived phenolic mixture was investigated for its solvent ability for extraction of a South African bituminous coal at temperatures of 300–360 °C. A previous study showed that phenol gave the highest ... -
Structural and chemical modifications of typical South African biomasses during torrefaction
Mafu, Lihle D.; Neomagus, Hein W.J.P.; Everson, Raymond C.; Strydom, Christien A.; Bunt, John R. (Elsevier, 2016)Torrefaction experiments were carried out for three typical South African biomass samples (softwood chips, hardwood chips and sweet sorghum bagasse) to a weight loss of 30 wt.%. During torrefaction, moisture, non-structural ... -
Sulphur capturing by an inertinite rich high ash bituminous coal during conversion in a pilot packed bed reactor
Skhonde, M. Pat; Strydom, Christien A.; Bunt, John R.; Schobert, Harold H. (Elsevier, 2011)Sulphur is liberated from the coal structure and released in various forms during coal thermal processing. The possibility of sulphur capture, through injection of SO2 into a packed coal bed in a pilot packed bed reactor ... -
The transient swelling behaviour of large (-20 + 16 mm) South African coal particles during low-temperature devolatilisation
Coetzee, Sansha; Neomagus, Hein W.J.P.; Bunt, John R.; Strydom, Christien A.; Schobert, Harold H. (Elsevier, 2014)In order to predict coal behaviour during certain utilisation processes, and to improve and develop coal conversion technologies, it is important to understand the swelling behaviour and plastic properties of coal. X-ray ...