M.Ing. / The dissertation is an investigation on the implementation of new technologies (five off) in a coal pulverising with main aim to optimise mill maintenance interventions. The technologies in question are: • Stationary air throat replaced with a rotating throat assembly. • Hydro-pneumatic mill loading cylinders replaced with airbags. • Classifier cone modification. • Introduction of triton material for the mill spider guide plates. • High chrome mill grinding balls. Every maintenance intervention, even if planned, negatively affects a plant’s availability and reliability. A Babcock and Wilcox (B&W) at Kriel power station (ESKOM) was used for the testing of the mentioned technologies. The mill model/size is a B&W 10.8E mill. The aim of the introduction of new technology on a mill is to optimise the period between required maintenance activities. A higher availability will assist in achieving good plant maintenance performance indicators. It needs to be noted that the dissertation focussed on the financial and technical parameters of a specific modification. This in an effort to increase uptime and reduce costs as part of a business drive for bigger profit margins. The new technologies tested were thus evaluated from a technical and financial point of view. Each technology was implemented at different time periods and nowhere was any tests performed in parallel on a single mill. To get approval from an investment committee for release of money for tests/modifications, technical and financial assumptions need to be made regarding the performance parameters of the modification/change. Once a modification is being tested, actual plant data can be used as inputs into the execution phase of the modification as assumptions can be replaced with test data. A financial model was developed to “test” the financial feasibility of the proposed changes/modifications. With new technology successful implemented in the plant the current maintenance strategies for maintenance interventions can be re-evaluated as the proposed modifications removed historic barriers that determined the current used based maintenance intervals. An example is where a mill is taken from service to replace or repair the stationary air throat (typically every 5 000 operating hours). With the newly applied technology (rotating throat assemblies), there is no need for maintenance interventions every 5 000hrs as a rotating throat assembly can run without major interventions for 60 000hrs.

A research report submitted to the School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, 2016. / The self-heating of coals is a complex problem which has been occurring for centuries. This problem has been fatal to coal miners, an economical challenge to coal mines and a health risk in a release of greenhouse gases to the public in general. Therefore, everyone is affected by the self-heating of coal, which leads to spontaneous combustion when the ignition temperature is reached. There are many test methods that have been used to test spontaneous combustion in coal, but all have one common factor or disadvantage of requiring long periods of time before a conclusion can be deduced. This then creates a need for a rapid and reliable method to test the liability of coal to self-heat in the coal industry and thus the motivation for this project. The thermogravimetry analysis (TGA) method was selected to test the liability of coal to self-heat due to its short analytical duration. The Smith-Glasser oxidation test was selected to validate the TGA results obtained. The main aim of this project is to investigate the reliability of the TGA method to predict the propensity of coal to self-heat. 29 samples from different regions of South Africa were used, prepared to 250 μm for all the analyses and self-heating tests. All samples were analysed for proximate, calorific value, sulphur and petrographic properties before the spontaneous combustion liability tests began. The TGA method followed two tests: 1) the O2 adsorption and 2) the ignition test. Five different heating rates (3, 5, 7, 10, and 20) °C/min were run in order to obtain five derivative slopes which would be used to obtain the TGspc index. The oxygen adsorption test studies the mass increase at low temperature under exposure of air between the temperature ranges of 100 – 300°C. The Smith-Glasser oxidation test method studies the reaction of coal with O2 and calculates the O2 absorbed per amount of coal tested. The Smith-Glasser test results collaborated with most of the other analytical results, and with the TGA results to a certain extent. The TGA spontaneous combustion liability test requires additional analytical work to back up its results because the results do not appear as accurate as the Smith-Glasser oxidation test. It also requires repeatability tests to ensure the integrity of the results. / EM2017

M.P.H., Faculty of Health Sciences, 2008 / Introduction The Department of Minerals and Energy (DME) in South Africa issued a Directive B7, titled “A Guideline for the Ventilating of Mechanical Miner Sections” to the coal mining industry. The main purpose of this directive was to reduce respirable dust exposures at the coal face with the long term objective of reducing the incidence of Coal Workers Pneumoconiosis (CWP). This study attempts to evaluate the appropriateness of the DME approach by comparing respirable coal dust results from personal samples from occupations at the coal face to the results obtained from engineering samples at the continuous miner. Objectives The objectives of this study are to: • Describe personal respirable coal dust concentrations of the occupations within the continuous miner Homogeneous Exposure Group (HEG) in five underground coal mines in Mpumalanga from January 2005 to December 2006. • Describe environmental engineering respirable coal dust concentrations of the continuous miner operator position in five underground coal mines in Mpumalanga from January 2005 to December 2006. • Compare personal respirable coal dust concentrations to Environmental Engineering Dust (EED) concentrations in five coal mines in Mpumalanga from January 2005 to December 2006. Methodology This study is descriptive in nature and was carried out utilizing historical respirable coal dust data from underground coal bord and pillar production sections. Data was supplied by Collieries Environmental Control Services (CECS) who provided a coal sampling and analysis service to South African collieries. Data provided was from five large underground coal mines in the Mpumalanga coal fields. The study population consisted of occupations within the HEG of workers deployed at the coal face who were linked to Continuous Miner (CM) production activities and results from EED sampling. Results When comparing the personal sampling results to EED sampling results for each individual mine, it is evident that all the mines had lower personal sampling results than EED results, thus establishing a definite trend. When combining all the mines in the two data sets it is also evident that EED sampling results are significantly higher than personal sampling results confirming the trend observed on individual mines. Correlation tests carried out between the two data sets indicated that there is no correlation between the personal and EED sampling results. The poor correlation between the two data sets indicates that the EED sampling position is not ideal and does not take account of the actual contaminant levels leaving the coal-winning heading. Discussion and conclusion The DME directive by way of a simple calculation took the countries personal Occupational Exposure Limit (OEL) of 2 mg/m3 and formulated a limit of 5 mg/m3 for EED sampling results. Simple extrapolation of the EED results indicates that personal exposure is exceeded more than two-fold and thus the limit of 5 mg/m3 as set by Directive B7 cannot be compared to the personal respirable coal dust OEL of 2 mg/m3. The basis of the initial calculation used to derive the 5 mg/m3 limit assumed that the shift lengths were in the region of 8 hours and cutting times around 40% of the shift, while most coal mines now have shift lengths ranging from 9 to 10 hours. In conclusion it is evident that the required limit of 5 mg/m3 as set out by Directive B7 cannot be related to the personal exposures limit of 2 mg/m3. Poor correlation results observed indicate that the EED sampling position does not account for the respirable dust concentrations leaving coal-winning headings and may be affected by the re-circulation of contaminated air over the sampling position. In addition the EED sampling position does not give an indication of the respirable dust capture efficiency of scrubber fans.

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography : leaves 146-149. / M.S.

Thesis. 1978. Sc.D.--Massachusetts Institute of Technology. Dept. of Chemical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 307-314. / Sc.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH / Bibliography: leaves 561-577. / by Daniel Alec Sargent. / Ph.D.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Bibliography: leaves 429-434. / by Richard John Quann. / Sc.D.

Este estudo foi feito a partir de uma amostra de carvão extraído na mina da Vale- Moçambique, localizada no distrito de Moatize, Província de Tete. O trabalho visa analisar o sistema de reagentes na flotação de finos de carvão mineral pertencente à camada UCB. Dentre os métodos de beneficiamento de carvão, a flotação se destaca como um dos mais importantes para a concentração deste material, em particular no tratamento de partículas finas. A alimentação total da planta de processamento da Vale- Moçambique é de 8000 tph de carvão, onde 10% dessa alimentação corresponde a fração fina que alimenta o circuito de flotação. O material utilizado nesse estudo apresentou uma granulometria 96% menor do que 0,25 mm. Os reagentes utilizados nos ensaios de flotação foram betacol e óleo diesel como agentes hidrofobizantes e MIBC como espumante. O intervalo de concentrações de betacol na primeira fase de ensaios foi de 200 g/t a 500 g/t, e na segunda fase foi de 200 g/t a 500g/t de óleo diesel e manteve-se constante o MIBC em 300 g/t. Os resultados mostraram que é possível, a partir de uma alimentação com o teor de cinzas em torno de 22,84%, obter produtos com teores abaixo de 10% de cinzas, com uma recuperação mássica em torno de 50%. A recuperação de matéria carbonosa também foi avaliada e apresentou resultados positivos. Complementando esse estudo, foi avaliado o efeito da recuperação de H2O e foi observado que para as concentrações de betacol as recuperações variaram de 6 a 9%, e para óleo diesel mais MIBC foram de 4 a7%. / This study was done from a sample of coal mined at the Vale-Mozambique mine, located in Moatize district, Tete Province. The aim of this work is to analyze the reagent system in the flotation of coal fines belonging to the UCB layer. Among coal processing methods, flotation stands out as one of the most important for the concentration of this material, in particular in the treatment of fine particles. The total feed of the Vale-Mozambique processing plant is 8000 tph of coal, where 10% of this feed corresponds to the fine fraction that feeds the flotation circuit. The material used in this study had a particle size of 96% smaller than 0.25 mm. The reagents used in the flotation tests were betacol and diesel oil as hydrophobizing agents and MIBC as frother. The range of betacol concentrations in the first test phase was 200 g / t at 500 g / t, and in the second phase 200 g / t at 500 g / t of diesel oil and MIBC were kept constant at 300 g / t. The results showed that it is possible, from a feed with the ash content around 22.84%, to obtain products with levels below of 10% ash, with a mass recovery around 50%. The recovery of carbonaceous matter was also evaluated and presented positive results. Complementing this study, the effect of H2O recovery was evaluated and it was observed that for the concentrations of betacol the recoveries ranged from 6 to 9%, and for diesel oil plus MIBC were 4 to 7%.

Thesis (Ph.D. (Engineering))--University of the Witwatersrand, Engineering Faculty (Civil Engineering), 1977 / The thesis deals with the development of improved road tarbinders in South Africa and their application in surface treatments and in mixes used for pavement wearing courses and base courses in this country. This work is timely in view of the country's current economic problems. Locally produced tarbinders are considerably less expensive than bitumen binders in inland areas; tar being produced in the Witwatersrand complex whereas locally refined bitumen is produced from imported crude oil. The annual expenditure on bitumen by the South African road industry is currently of the order of R26 000 0 0 0. However, previously it had been found that tarbinders were less durable than bitumen. [Abbreviated Abstract. Open document to view full version] / WS2017

Thesis (Ph.D. (Agriculture)) -- University of Limpopo, 2018 / Surface coal mining requires good and sound rehabilitation practices to re-establish productive land capability and land use after mine-closure. The vast majority of Mpumalanga’s coal deposits are located below high quality and productive arable land. Impacts on soil and land, associated with surface coal mining can reduce the possibility to re-establish the pre-mining land capability and productive potential. Stockpiled soils are excavated from the ground during mining activities, and piled on the surface of the soil for rehabilitation purposes. These soils are often characterized by low Soil Organic Matter (SOM) content, low fertility, and poor physical, chemical and biological properties, limiting their capability for sustainable vegetation growth. The aim of this study was to assess coal-mine stockpile soil quality and its impacts on vegetation using laboratory techniques and Reflectance Spectroscopy. Firstly, the impact of quality of coal-mine stockpile soils on sustainable vegetation growth and productivity was investigated. Soils were collected at three different depths (surface (0-25cm), mid (150-200cm) and deep (300-350cm)), as well as mixed (equal proportion of surface, mid and deep) from two stockpiles (named stockpile 1: aged 10 and stockpile 2:20 years) at the coal mine near Witbank in Mpumalanga Province, South Africa. Soils were amended with different organic and inorganic fertilizer. A 2 x 4 x 5 factorial experiment in a randomized complete block design with four replications was established under greenhouse condition. A grass species (Digiteria eriantha) was planted in pots with unamends and amended soils under the greenhouse condition at ambient temperatures of 26-280C during the day and 16.5-18.50C at night. Mean values of plant height, plant cover, total fresh biomass (roots, stems and leaves) and total dry biomass were found to be higher in the stockpile 1 than in stockpile 2 soils. On average, plants grown on soils with amendments yielded plant height that was 98.28% higher than plants grown on soil with no amendment. On average, height of plants grown on soil amended with poultry manure and lime was 44.65% higher compared to plants planted on soils amended with NPK + lime, compost and poultry manure. On average, mixed soils had better vegetation growth than soil from the individual depths. In total, dry biomass and plant height of plants grown on mixed soils was 33.56% and 22.34% higher than plants grown on surface, mid and deep soils. Mixing soils changes texture, which might affect other physical properties like water availability, infiltration rate and aeration and, to some extent, chemical properties.Secondly, the effect of soil amendments on enzyme activity of coal-mine stockpile soil was investigated. The activity of β-glucosidase, alkaline phosphatase, acid phosphatase and urease was analysed after harvest of grass species (Digiteria eriantha). The results show significantly high activity for β-glucosidase, alkaline phosphatase and urease when soils were amended with poultry manure + lime. Soils with no fertilizer yielded significantly low enzyme activity compared to soil amended with poultry manure+ lime, NPK + lime, sole application of poultry and in some instances compost application. β-glucosidase, urease and acid phosphatase mean values generally tend to decrease with an increase in soil depth. β-glucosidase activity for surface soil was found to be 18.06% higher than that of mid and deep soil. The stockpile depth plays a major role in biochemical activities of the soil; deep soils, in most cases, have decreased microbial biomass and enzyme activity due to oxygen and moisture availability. The results for the effect of organic and inorganic amendment on stockpile soil showed that on average, alkaline phosphatase activity following the application of poultry manure + lime was 17.69% higher than that of lime + inorganic fertilizers (NPK). On average, the acid phosphatase activity following the application of lime + NPK was 56.33% higher than that of poultry manure + lime, compost, soil with no fertilizer as well as sole poultry manure. Urease activity for soil with no fertilizer was found to be 84.70% lower than that of soil amended with poultry + lime. The increase in enzyme activity was attributed to change in soil pH due to application of amendments. A comparison of the two stockpiles indicated that, stockpile 2 (20-year old) had low enzyme activity compared to stockpile 1 (10-year old). The activity of β-glucosidase, acid phosphatase, alkaline phosphatase and urease was found to be 11.03%, 8.04%, 10.03% and 60.23% respectively, higher on stockpile 1, relative to stockpile 2 soils. When soils are stockpiled for a long period of time, microbial biomass is reduced and that affect enzyme activity because microbial biomass is considered as the primary source of enzymes in the soil. Thirdly, the capability to estimate coal-mine stockpile soil properties using Reflectance Spectroscopy was investigated. Soil from coal-mine stockpiles were air dried, crushed, sieved and analysed using laboratory methods. The following soil properties: exchangeable calcium (Ca), sodium (Na), magnesium (Mg), potassium (K), soil pH, organic carbon (OC), phosphorus (P) and clay content were analysed as they are important for vegetation re-establishment during rehabilitation. Spectral reflectance of the soil samples was measured using FieldSpec 3 Portable Analytical Spectral Device (ASD®) spectrometer. Partial Least Square Regression (PLSR) was used to estimate various soil properties, in combination with various spectral transformation techniques such as untransformed reflectance spectra, First Derivative Reflectance (FD) and Log transformed spectra Log (1/R). To assess the performance of various predictive models, R2 (Coefficient of Determination), Root Mean Squares Error of Validation (RMSEV) and Variable Importance in the Projection (VIP) values were computed. The results showed that pH and Ca were accurately estimated (R2=0.79 and 0.69 and RMSEV=0.52 and 0.89cmol/kg respectively) using Log (1/R) reflectance as compared to other soil properties achieving R2 less than 0.5. Ca has strong correlation with pH. Ca expressed in soil solutions is mostly related to pH, which is what was attributed to accurate prediction of both Ca and pH. Soil pH in most cases is directly influenced by calcium carbonate content in the soil. Although the performance of other soil properties was poor, they were highly correlated with pH and Ca except for K. K is soluble and mobile and is therefore subject to leaching in most soils resulting in low K concentrations. Low K concentrations results in higher variability and lower R2 values.Finally, the capability of Partial Least Square Regression and Reflectance Spectroscopy to estimate the effect of coal-mine stockpile soil on foliar nitrogen and phosphorus content was investigated. Grass samples were collected from coal-mine stockpile soils and the adjacent unmined soils at open-cast coal mine around Witbank area in Mpumalanga Province, South Africa. Samples were oven dried and analysed for foliar N and P concentration in the laboratory. Spectral reflectance of the dried grass samples were measured using Analytical Spectral Device (ASD) - FieldSpec 3. Partial Least Square.Regression (PLSR) was used to estimate N and P concentration, in combination with various spectral transformation techniques such as First Derivative Reflectance (FDR) and Log transformed spectra Log (1/R). The results show that stockpile soils appear to impact foliar N and P concentration as evidenced by low N and P concentration in the grass, sampled from stockpile soils compared to grass sampled from unmined soils. This was attributed to soil nutrient status of the study sites, as unmined sites had high soil nutrient content than stockpile soils. Foliar N concentration of grass sampled from stockpile soils and unmined soils can accurately be estimated without spectral transformation. FD yielded highest R2 for N and P estimation in grass sampled from both stockpile soils and unmined soils.Overall, the study shows that stockpiling affect soil quality, enzyme activity and vegetation growth. It further shows that soil amendments can improve soil quality and enzyme activity of coal-mine stockpile soils. Finally, Reflectance Spectroscopy can be used to estimate coal-mine stockpile soil properties, its quality and foliar N and P content as an indicator of vegetation nutrient stress. / National Research Foundation