The effect of manipulated variables on the flotation response of run-of-mine coal supplied by Bullmoose Coal Mine (North East British Columbia) was studied in a pilot flotation column and a batch mechanical cell using experimental designs of the factorial class after the coal had been stage crushed and ground to about 96 percent minus 600 µm, the feed size to the flotation circuit at Bullmoose Coal Mine. The objective was to optimise statistically the two flotation units usings (1) screening designs, (2) the steepest ascent technique, and (3) central composite designs, and to compare cell performance. The efficiency index was employed as the primary optimisation criterion. The two cells yielded comparable efficiency indices, but the product ash content of clean coal from the flotation column was consistently lower. Evaluation of the efficiency indices of individual size fractions was also carried out at the optimum conditions of each cell. The approach taken was to separate the feed into individual size fractions, retain the fractions separately, and float them separately. The flotation column yielded higher efficiency indices and lower product ash content when a feed with 15 percent solids was floated. Results obtained by floating individual size fractions at 2 percent solids indicated that it is difficult to float sizes above 300 µm in both cells at such a low pulp density. Below 300 µm, the performance of both cells was comparable. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

The influence of aggregate and binder phase characteristics on formcoke products has been studied. This involved investigating the compaction kinetics of the system and determining the mechanical strength of the briquettes produced. The char phase was characterized in terms of density, hardness, porosity and residual volatile matter content and the rheological properties of the binder phases used were established elsewhere. The strength and wetting behaviour of the aggregate-binder interface were studied using model materials (an SRC pitch binder and a graphite rod aggregate) as well as those produced in this work. Analysis of compaction curves was carried out using the CCWL Hot Compaction Model for Char-Binder Coal systems which was found to adequately describe the observed compaction behaviour. Briquette strength was characterized by ultimate compressive strength and comparisons were made for a constant briquette bulk porosity of 35% (by volume). Results indicate that binder phase fluidity affects compaction viscosity during the particle flow stage of compaction and that char porosity influences final briquette bulk density by affecting the amount of total compaction required to obtain a given bulk density. In general, increased total compaction was shown to result in higher product bulk density and high bulk density was found to yield higher gross composite strength. The latter relationship was seen to be approximately linear over the range of bulk porosity encountered in this study. A higher briquette strength was found for systems with aggregates carbonized at lower temperatures. This was attributed to a combination of higher porosity and stronger char-binder interfacial strength, although the former effect was considered to predominate in the systems considered here. Binder phase fluidity was also seen to affect briquette strength, higher fluidity resulting in higher strength. It was concluded that this was due to increased binder penetration of the aggregate phase. With no significant pore structure in the aggregate, as found with high temperature char, briquette strength was seen to become approximately constant for the three binder coals used. It was concluded that a good formcoke product was aided by a highly fluid binder and a char pore structure accessible to the binder phase. / Applied Science, Faculty of / Materials Engineering, Department of / Unknown

Three different Western Canadian coals were gasified with air and steam in a fluidized bed of 0.73 mm Ottawa sand and coal, at atmospheric pressure, and temperatures of 1023 - 1175 K to produce a low Btu gas. The coals tested were of two types: one non-caking and two caking coals. The results were compared with those previously obtained for the same three coals when gasified in essentially the same equipment, but operated as a spouted bed. The effects of temperature, coal feed rate, air to coal ratio, steam to coal ratio, coal quality, coal particle size, and bed depth on the gas composition, gas calorific value and the operating stability of the gasifier, were established by running gasification tests over a wide range of operating conditions. Typical calorific value of the gas obtained for all three coals was in the range of 2.0 - 2.6 MJ/m³, which is lower than reported for the spouted bed and commercially available fluidized bed gasifiers. Analysis of the results suggested that in the present low temperature gasifier, the combustion and pyrolysis reactions predominate over the gasification reactions. The ability to treat caking coals in fluidized bed and spouted bed reactors is discussed. It is concluded that the dispersion of coal in a bed of inert silica and ash, rather than hydrodynamic characteristics is the key-factor in their success in handling caking coals. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Unknown

Coal pyrolysis has been studied in a 12.8 cm diameter continuous spouted bed reactor with the aim of determining conditions for maximum liquid yields from Western Canadian coals. Coals studied included two British Columbia bituminous coals and one Alberta sub-bituminous coal. The basic characteristics of the spouted bed pyrolyzer were determined by carrying out experiments over a range of spouting gas velocities and composition, coal feed rates and particle size, reactor temperatures, and bed heights. The process was assessed by measuring the yields and compositions of the tar, char, and gas. Nitrogen and nitrogen/carbon dioxide mixtures and coal of size - 3.36 + 1.19 mm were fed at atmospheric pressure to an electrically heated reactor containing sand. The tar yield was determined by sampling the outlet gas through a series of cooled impingers. The spouted bed pyrolyzer behaves in a manner similar to a fluidized bed unit, and shows a maximum tar yield with temperature at a fixed feed rate. At a given pyrolyzer temperature, the tar yield was inversely proportional to the coal feed rate over the range 0.4 to 7.6 kg/h. This effect is attributed to the detrimental effect on tar yield of the increasing amounts of char present in the reactor as coal feed rate increases. Coal type strongly influenced the liquid yields as expected. Sukunka bituminous coal from the Peace River coal field gave a maximum tar yield at 600°C of 31% wt/wt MAF coal. The corresponding gas yield was 3.6%, and the char yield was 64%. The maximum tar yield from Balmer bituminous coal from Crowsnest coal field was 19.4% wt/wt MAF coal at 580°C while that from a high-ash Balmer bituminous coal was 12.1% at 620°C. Forestburg sub-bituminous coal from the Edmonton formation gave a maximum tar yield of 21% at 530°C and significantly higher gas yields of 20% versus 6% for the bituminous coals due to higher C02 production. With Sukunka coal, a steady increase in tar yield from 20.4 to 26.7% wt/wt MAF coal at 580°C was found as the average coal particle size was reduced from 2.28 to 0.65 mm. No significant effects on tar yield were found for variations in spouted bed depth, or vapour residence time over the range 0.68 -1.15 s. No serious problems were encountered with agglomeration. Composition of gas, tar and char are presented for conditions of maximum tar yield for the various coals tested. The H/C atomic ratio of the tars was as high as twice that of the parent coal. Oxygen, sulphur and nitrogen together represent up to 10 wt% of the bituminous coal tars, which suggests considerable upgrading will be necessary to produce liquids of quality comparable to petroleum oils. The total volatiles yield data were well represented by a first order kinetic model. An activation energy of 4.71 kcal/mole was obtained for the sub-bituminous coal while that for the bituminous coals was 14.1 kcal/mole. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The future of coal mining in the Witbank Coalfield over the next 30 years and beyond depends on effective and responsible utilization of the remaining reserves, both within unmined and previously mined areas. Similar to all mineral resources, coal is also non-renewable and the current resources will not last forever. Unlike most other resources coal resources have to be considered in long term strategic planning for energy supply. It has therefore become very important to use the remaining resources and reserves to their full potential. This has prompted mining companies to re-mine or do secondary extraction of areas mined during the previous 50 years. Reliable and internationally accepted valuation techniques and reporting standards are well established for virgin areas. The challenge is now to develop an equally robust and reliable system for remaining resources and reserves in previously mined areas. A number of established operations already exist in South Africa and internationally which are utilizing such reserves. Due to numerous factors affecting the viability of this type of operation a system or matrix is proposed for defining such resources and reserves. This classification scheme caters for the obvious geological, mining and beneficiation factors, and also for the multitude of lesser known but equally important factors. The effects of some of these factors on a future mining operation are demonstrated in a case study of such a previously mined area. Factors affecting the Run of Mine (ROM) tons and saleable tons are: a) derating percentage b) percentage mining extraction c) percentage dilution and contamination d) percentage fines generated e) spontaneous combustion Numerous pitfalls are identified such as top coaled areas, water accumulations, no access to old areas to verify existing information and the time lapsed since previous mining occurred. Another complicating factor is the lack of a method for the quantification of the impact of spontaneous combustion on remaining reserves. The financial viability of mining these areas are especially sensitive to the coal price, R/$ exchange rate, change in production and capital expenditure. The information generated during the investigation is processed in a financial model which is used to evaluate different scenarios and risk sensitivities. It is demonstrated that in evaluating previously mined areas, it is not the obvious factors that often determine the financial viability of a project, but rather the not so obvious financial factors. / Dissertation (MSc (Geology))--University of Pretoria, 2008. / Geology / unrestricted

MPH, Occupational Hygiene,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand / Introduction Coal mine workers are exposed to a mixture of dusts including coal dust and silica (as alpha quartz), in this respect the mixture of dusts is termed mixed coal dust. The illnesses commonly associated with the inhalation of mixed coal dust are (1) coal workers’ pneumoconiosis, (2) silicosis, and (3) chronic obstructive pulmonary disease. Objectives The main aim of this research report is to determine whether current dust levels in Mpumalanga coal mines were above generally recommended standards and to review information on the burden of coal associated diseases in the coal miners of Mpumalanga. The objectives of this research project are (1) to describe the coal dust and silica concentrations as measured by personal breathing zone sampling in Mpumalanga coal mines over the period 2003 to 2006 and (2) to describe the burden of coal-associated diseases reported by autopsy examinations received from NIOH Pathology Department and in the SAMODD data base in Mpumalanga coal mines over the period 2002 to 2006. Page 4 of 71 Methods Dust Personal breathing zone sampling data were obtained from gravimetric sampling programmes established according to the DMR – SAMOHP from fifty three coal mines in the Mpumalanga region. During the time of the study, the sampling programme strategies were co-ordinated by a central laboratory services: “Colliery Environmental Control Services”. The raw data were obtained from this laboratory for the periods 2003 to 2006 in Microsoft excel spread sheet format. Burden of disease NIOH - PATHAUT The annual reports of the NIOH on the autopsy data for the coal mining sector were obtained from the web site of NIOH. Sample data sheets were drawn up to extract only relevant information from the reports. DMR - SAMODD The DMR collects medical information from coal mines across South Africa, and this information was obtained from the local inspectorate. The data contained in the report were of all the mines in South Africa, a filter was applied in a Microsoft Excel spread sheet to extract the relevant information for Mpumalanga coal mines. Page 5 of 71 Results Dust There was a reduction in the recorded concentration of respirable dust levels in the collieries over the four year period 2003 to 2006. The average coal dust exposures fell from 1.9 mg/m³ in 2003 to 1.3 mg/m³ in 2006. The Department of Mineral Resources places emphasis on the 90th percentile and most of the sampling strategies are centred on this figure. Although the 90th percentile decreased from 4.82 mg/m³ to 3.02 mg/m³ (i.e. 1.8 mg/m³) over the four year period, this level is still unacceptable as it is above the required statutory limit of 2.0 mg/m³. Silica exposures also showed a reduction from an average of 0.047 mg/m³ in 2003 to 0.034 mg/m³ in 2006. Disease burden: PATHAUT Pulmonary tuberculosis - the number of employees at autopsy with pulmonary tuberculosis (PTB) decreased from 12 in 2002 to 8 in 2006, but there is not enough information to establish a trend over the five year period. Silicosis: - the number of employees at autopsy with silicosis was between 3 to 4 cases per year except in 2004 where there was an outlier of 11, but in general the cases stayed constant over the five year period. The rate of silicosis per 1000 Page 6 of 71 autopsies however indicates an increase over the five year period as the rate increased from 37 to 52. Emphysema: - the number of emphysema cases stayed fairly constant with 32 cases in 2002 and 30 cases in 2006, but with an increase in 2003 and 2004 to 42 and 43 respectively. The rate per 1000 autopsies increased from 294 in 2002 to 390 in 2006. Coal workers’ pneumoconiosis: - there was a decrease in coal workers’ pneumoconiosis from 2002 to 2006 from 10 to 2 cases, but there were 11 and 15 cases in 2003 and 2004. SAMODD Coal workers’ pneumoconiosis: - the total number of employees reported with Coal Workers Pneumoconiosis (CWP) decreased for the period 2003 to 2006, from 12 in 2003 to three in 2006. Chronic obstructive pulmonary disease: - No useful information was available for this illness. Silicosis: - One case was reported in 2002, and 2 cases in 2003 and 2004, no cases were reported for 2005. Tuberculosis: - with initially only three cases in 2002, cases increased during 2003 to 2005 to 53, 44 and 50 respectively. A reduction was observed in 2006 to 13 cases. Page 7 of 71 Conclusion There may be an overall reduction in the dustiness of the coal mining industry in Mpumalanga province as the arithmetic mean of the samples collected decreased from 1.9 to 1.3 mg/m³ over the four year period 2003 to 2006. The level of exposures to silica might be lower because the exposures reduced from a mean of 0.047 in 2003 to a mean of 0.034 mg/m³ in 2006. The recorded data suggest a decline in CWP; this is in line with international data from the United Kingdom, USA, Australia, Germany, France and Belgium. Pulmonary tuberculosis - was constant over the five year period based on limited autopsy data, but the SAMODD data base indicates a decline for the year 2006 but overall shows an increase in the number of tuberculosis cases in Mpumalanga coal mines. Silicosis cases were fairly constant, but the rate per 1000 autopsies increased by 15/1000 over the five year period. The number of recorded cases from the DMR SAMODD is too few to make any useful deductions. Emphysema numbers were constant, but the rate per 1000 autopsies increased by 96/1000 over the five year period. No useful interpretation can be made from the data received from the DMR on chronic obstructive pulmonary disease.

Carbon is a necessary reductant in steel production to convert iron ore to metallic iron. The use of coal and coke causes CO2 emissions to be released into the environment. Using bio-based carbon sources has the potential to offset these emissions and reduce cokemaking overall carbon footprint. The use of biomaterial in coal blends reduces the fossil fuel requirements but to what capacity and type of biocarbon can replace coal is unknown. The full effects of coal and coke characterization from the addition of biomaterial are unknown. In this work, raw biomaterials available to industrial users were evaluated for substitution at low amounts in operational coal blends. Physically, the optical properties of carbon coke forms can provide insight into the strength, reactivity, and performance in the blast furnace, resulting from coal rank and type. The interaction of the biomaterial substitutions with coal during the coking process is evaluated to better understand the reduction in coke strength after reaction (CSR). For this purpose, a series of the pilot oven and sole heated oven tests were performed. When coal was substituted with low amounts of raw biomaterials, the most notable changes in coke texture analysis were to incipient and circular textures. In this work, data from a series of pilot oven and sole heated oven tests showed that fine coke textures and overall inerts increased. The changes in coke textures can be linked to decreases in coke strength after reaction (CSR). / Thesis / Master of Applied Science (MASc) / Metallurgical coke remains the main fuel and reductant source for ironmaking by blast furnace operation. Quality metallurgical coal, a fossil fuel, is required to produce coke. This work continues ongoing steel industry research investigating biomaterial substitution of coal as a more sustainable option. Coal is considered a new release of greenhouse gas (GHG) emissions when used in the steelmaking process compared to a biomaterial which is regarded as a GHG neutral replacement. Three raw biomaterials, available to industrial users, were evaluated for substitution at low amounts and compared to an operational coal blend. The substitution could allow for GHG emissions of the cokemaking processes to be reduced if quality coke can be produced. The interaction of the biomaterial substitutions with coal during the coking process is evaluated in this work to better understand the resultant coke textures related to reduction in coke strength from the substitution.

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