M.Com. (Mineral Economics) / South Africa support is one of the world's fastest growing populations. By the year 2000 AD, South Africa's population is predicted to be 225% larger than it was in 1970. By 2000 AD the total population will have grown to over 54 million people, representing a compound growth rate of some 2,7% Per annum over the preceding 30 years. How will this hlrgeoning population be housed? Where will the growth be? It has been predicted, from numerous sources, that the non-European urban population will soar and thereby account for the bulk of the forecast growth. 'Ibis group will grow from 6 million in 1970 to 25 million by the year 2000, a rate of 4,9% Per annum, Whereas, the urban European population growth shall be :relatively static. Clearly, this phase of mass-urbanization will have to be accompanied by general socio-economic upliftment of the community as a whole. In this regard, the demand for housing, particularly low cost housing, will rise sharply. In South Africa today, many a prospectiive entrepreneur has identified this situation as an opportunity to establish a building-materials manufacturing plant. Because a brickworks is commonly believed to be a relatively simple operation to ,establish and run profitably, many entrepreneurs have applied their resources to this field. In reality, a small scale operation is found to be barely profitable and financial failure in this regard is relatively common. 'Ibis dissertation investigates why such a paradox should exist. A host of variables, which can become major pitfalls to a fledgling brick making business, are discussed. Possible hurdles facing such an operation range from raw material properties, the plant's . financial structure, to characteristics of the brick market be understanding of the interactions between these relatively complex facets of brick making, requires a multi-disciplinary approach. The discipline of Mineral Economics is ideally suited to address the range of problems facing the entrepreneurs, who attempt to establish a small brick plant.

This thesis explores the issues surrounding the ruins of the Clayburn Company Ltd. Since its demolition in 1930, the original source of pride and income for the company town has become more and more invisible except in the memories of some long-term residents. Now that the village is populated by a new generation that wishes to rejuvenate and adopt the idealistic past of Clayburn Village, interest has turned to the overgrown lot where the factory once stood. For the rest of the village, the path to revitalizing Clayburn Village has been obvious. Many of the most important houses and three non-residential structures still stand and have been restored. However, only traces of the brick factory remain, leaving the options about how to pay homage more various and less obvious. This paper relates a history of Clayburn, then explores the construction of histories and the importance of artifacts to support those histories. In this case the artifacts in question are buildings. Current actions being taken to restore the built heritage of the village demonstrate the commitment on the part of residents to that means of preserving their history. Possible options are explored, from low to high levels of intervention, ranging from leaving the ruins to the attrition of time, until they finally dissolve, to building directly over the ruins with an obviously new building. The proposed plan for the site takes a stance between these two extremes. The program for the site includes a visitor's centre of modern design, that is not located where buildings previously existed, and landscape elements that mark the former locations of brick plant buildings. A careful weighing of several criteria, including the desire to impart as much information as possible, while not confusing the visitor as to antiquity or detracting from the future use of the site as a green space, resulted in the final design. The value of the experience of the ruins as a project in progress was also felt to be important.

Face à la demande énergétique de plus en plus croissante, et les problèmes environnementaux qui en découlent, la biomasse, en tant que vecteur énergétique et en association avec des techniques thermochimiques de conversion en gaz combustibles, pourrait être un vecteur énergétique intéressant s’il est produit de manière durable. En effet, accroitre le bouquet énergétique, en substituant d’avantage les énergies fossiles par des énergies renouvelables est devenu une réalité incontournable. De ce fait, les résidus agro-sylvo-pastoraux présentent un potentiel important au Sénégal en général et en particulier dans la région de Ziguinchor jadis appelée grenier du Sénégal, et des technologies de valorisation comme la pyrolyse et gazéification se trouvent parmi les voies les plus prometteuses pour la production d’énergie. Ainsi le modèle dynamique de Saeman basé sur la détermination des propriétés intrinsèques des résidus utilisés a été mis en œuvre afin de simuler l’écoulement de la charge de coques de cajou, de palme et d’arachide. Le modèle dynamique ainsi développé va permettre d'étudier l’influence des conditions opératoires et propriétés rhéologiques sur les profils de chargement, qui conduiront par la suite aux meilleurs transferts de chaleur et de masse dans les fours tournants en situation inerte comme réactive. Les meilleures conditions expérimentales retenues pour cette étude hydrodynamique sont : des vitesses de rotations comprises entre 2 - 4 tr/min, une inclinaison de 1°, et un rapport longueur sur diamètre supérieur ou égal à 0,05. La gazéification des trois résidus sous différents atmosphères (100 % -H2O, 75 % -H2O / 25 %- CO2, 50 % -H2O / 50 % -CO2, 25 % -H2O / 75 % -CO2, et 100 % -CO2) et à différentes températures comprises entre 950 - 1050 °C dans un réacteur à lit fixe ont permis de valider les résultats issus de la littérature qui mettent bien en évidence l’effet positif de la température sur la cinétique de gazéification des différents chars de résidus de biomasse. La pyrolyse de nos trois échantillons donne ainsi des rendements qui sont de 36,44 % pour la coque d’arachide, 37,28 % pour la coque de cajou et 39,97 % pour la coque de palme et quant à leur gazéification, elle conduit respectivement à des énergies d’activation comprises entre 110 - 126 kJ/mol, 104 - 125 kJ/mol et 116 - 150 kJ/mol. Les mesures expérimentales montrent aussi l’influence de la température sur la valeur du PCI des gaz obtenus (8 - 12 MJ/Nm3) et que ce PCI des gaz est inversement proportionnel à la taille des particules de biomasse. Par ailleurs la gazéification sous atmosphère mixte de vapeur d’eau et de gaz carbonique a montré que la réactivité des différents chars est fonction de l’augmentation de la concentration en vapeur d’eau. Le bilan global d’une telle étude expérimentale sur l’hydrodynamique et sur la dégradation thermique visant la maîtrise des phénomènes au sein des fours tournants permet ainsi une première analyse dans la mise en place de combustibles alternatifs pour la valorisation des potentialités locales de la région verte de la Casamance. / In view of the growing energy demand and the resulting environmental problems, biomass as an energy vector and at combination with thermochemical techniques for conversion into combustible gases, could be an interesting energy vector if it is produced in a sustainable manner. Indeed, increasing the energy mix, by replacing fossil fuels with renewable energies, has become an undeniable reality. As a result, agro-sylvo-pastoral residues have significant potential in Senegal in general and in particular in Ziguinchor region, formerly known as Senegal's granary, and valorisation technologies such as pyrolysis and gasification are among the most promising way for energy production. The Seaman’s dynamic model based on the determination of the intrinsic properties of the residues used has been implemented in order to simulate the flow of cashew, palm and peanut shells. Thus, the dynamic model developed will make it possible to study the influence of the operating conditions and rheological properties on the loading profiles which will conduct later of the best heat and mass transfers in the rotating furnaces in inert and reactive conditions. The best experimental conditions for this hydrodynamic study are: rotational speeds between 2 - 4 rpm, inclination of 1 °, and length to diameter ratio greater than or equal to 0.05. The gasification of the three residues under different atmospheres (100 % -H2O, 75 % -H2O / 25 %-CO2, 50 % -H2O / 50 % -CO2, 25 % -H2O / 75 % -CO2, and 100 % -CO2) and at different temperatures between 950 - 1050 °C in a fixed bed reactor enable to validate the results from the literature which clearly show the positive effect of temperature on the gasification kinetics of the various chars. The pyrolysis of our three samples gives yields of 36.44 % for the peanut shell, 37.28 % for the cashew shell and 39.97 % for the palm shell; and when gasified, it leads respectively at activation energies between 110 - 126 kJ / mol, 104 - 125 kJ / mol and 116 - 150 kJ / mol. The experimental measurements also show the influence of temperature on the Lower heating gas values (LHV) obtained (8 - 12 MJ/Nm3) and that, this LHV of gas is inversely proportional to the size of the biomass particles. Moreover, the gasification under mixed atmosphere of steam and carbon dioxide showed that the reactivity of the different chars depend on the increase of the concentration of water vapor. The overall assessment of such an experimental study on the hydrodynamic and thermal degradation of our residues aimed at controlling the phenomena within rotating furnaces (kilns) allows an initial analysis in the setting up of alternative fuels for the valorization of the local potentialities of the green region of Casamance.

This thesis explores the issues surrounding the ruins of the Clayburn Company Ltd. Since its demolition in 1930, the original source of pride and income for the company town has become more and more invisible except in the memories of some long-term residents. Now that the village is populated by a new generation that wishes to rejuvenate and adopt the idealistic past of Clayburn Village, interest has turned to the overgrown lot where the factory once stood. For the rest of the village, the path to revitalizing Clayburn Village has been obvious. Many of the most important houses and three non-residential structures still stand and have been restored. However, only traces of the brick factory remain, leaving the options about how to pay homage more various and less obvious. This paper relates a history of Clayburn, then explores the construction of histories and the importance of artifacts to support those histories. In this case the artifacts in question are buildings. Current actions being taken to restore the built heritage of the village demonstrate the commitment on the part of residents to that means of preserving their history. Possible options are explored, from low to high levels of intervention, ranging from leaving the ruins to the attrition of time, until they finally dissolve, to building directly over the ruins with an obviously new building. The proposed plan for the site takes a stance between these two extremes. The program for the site includes a visitor's centre of modern design, that is not located where buildings previously existed, and landscape elements that mark the former locations of brick plant buildings. A careful weighing of several criteria, including the desire to impart as much information as possible, while not confusing the visitor as to antiquity or detracting from the future use of the site as a green space, resulted in the final design. The value of the experience of the ruins as a project in progress was also felt to be important. / Applied Science, Faculty of / Architecture and Landscape Architecture (SALA), School of / Graduate

Those who today hear the name Djurhamn are maybe first thinking of a summer resort place with sunbathing, swimming and recreational boating activities. Djurhamn has an interesting and fascinating history well intertwined with the history of Sweden. The interesting history was exposed by the Stockholm Sport Diving Club which, during the summers of 1964 and 1965, brought up a large number of finds from the bottom of Djurhamn. The findings could essentially be dated to be in the in the period 1500s to 1700s. Like other parts of the East Coast Djurhamn was hit in "Russian raids" in the early 1700s. The known meetings of warships during the Vasa era and the history of naval ship Riskswasas fate also reflects the interesting parts of Djurhamn history. While working on this, a number of dives were made at the bottom of the basin in Djurhamn. Two side-scan surveys have also been conducted. Overall, this has not resulted in any change of the picture of what's on Djurhamns bottom. A previously unknown wreck that lies south of the cemetery have, however, been located based on information from the public. The finds from the dives during 1964 and 1965 talk about food and drinks, cooking utensils, three-leg pots and bottles speaks their language. Even earlier dated bargain materials speak the same language. It is a place where everyday objects leave imprints on the bottom along with the testimony of a brickyard, which flourished for a short period. Which traces have been left from the naval activities? Practically none. On land there are no naval monuments. The objects which were brought up at the 1960 dives were almost entirely attributable to the applications connected to cooking. Our modern society is a complex reality. There are homes, workplaces, hospitals, places of entertainment, etc. People are born, grow up, grow old and die. What do we find in the signs of the Djurhamn? Well, a picture that much is a reflection of today's society. Also here you are born grown up grown old and finally dead. Heavy drinking has flourished. In addition to self-household and shipping, there has been brick industry and cholera quarantine. Finally, perhaps Djurhamn over time is best described as farmers, fishermen and hungry sailors’ history more than the history of the fleet in the Vasa kings’ service.

MESMEG / Department of Mining and Environmental Geology / Although clay brick manufacturing has been going on for many years in South Africa, informal small-scale clay brick manufacturing enterprises are not officially regulated. Consequently, informal brick makers in the study area do not adhere to the demanding requirements of the South African National Standards for burnt clay masonry. Therefore, their clay bricks lack uniformity in terms of quality. Preliminary work revealed that over time, buildings constructed with these bricks develop cracks, thereby compromising safety. The importance of product quality management is not well understood in the informal brick manufacturing enterprises. As a result, they do not have any product quality management guidelines. The main purpose of this research was to develop the product quality management guidelines for ensuring quality in small-scale brick making enterprises in Dididi area. The specific objectives were to characterize the raw materials for clay brick manufacturing, identify and assess the technical problems of clay brick production, analyse the process of clay brick production and determine areas where product quality improvement is warranted. The research involved fieldwork which included soil sampling, analysis of clay brick production through the use of questionnaires and onsite observation of the production process, collection of samples of burnt bricks which were examined for compressive strength, water absorption as well as dimension measurements. These were then compared with the prescribed quality standards. Laboratory analyses of samples of raw materials were conducted and these included sieve analysis which was conducted in order to establish the particle size distribution of the raw materials; Atterberg limit tests were conducted in order to establish the physical characteristics of the soil. Chemical and mineralogical analyses were carried out to determine the chemical and mineralogical composition of the soil using XRF and XRD respectively. The textural characterisation of the material revealed abundance of sand sized particles and significantly low amounts of clay and silt. The plasticity of the soil used for bricks manufacturing in the study area was found to be ranging from slight to medium plasticity. Chemical analysis showed elevated silica contents with minor amounts of alumina and iron oxide. XRD analysis revealed the dominance of non-clay minerals with the highest concentration of quartz. The average compressive strengths of the tested brick samples for site A was 3.8, and 2.9 and 3.8 MPa for sites B and C respectively. The water absorption of the bricks was 13.5, 15.0 and 16.1% for samples from Site A, B and C respectively. The bricks dimensions met the recommended standards although their sizes were not uniform. v The survey conducted on brick manufacturing process revealed that the technical inefficiencies were mostly influenced by human and mechanical factors as well as the material inappropriateness. The production process was found to be too manual and labour intensive. Selection of the raw materials for brick manufacturing was based on indigenous knowledge and experience and most of the brick manufacturers lacked the prerequisite experience for making quality bricks. On the basis of the results of this research, it can be concluded that the materials used for manufacturing of clay bricks in Dididi are not well suited for making good quality bricks due to the reduced plasticity of the soil and the high concentration of quartz. These render the bricks brittle. It was also concluded that the production process also contributes to the poor quality of the bricks as the nature of the process was too manual. Selection of materials based merely on knowledge and experience and no scientific tests resulted in selection of inadequate materials which in turn affect the quality of the final bricks. It is therefore recommended that plastic clays be added to the raw clay materials to enhance its moulding property. In addition, materials such as internal fuels and anti-shrinkage materials should be incorporated into the process cycle to prevent cracking during drying and firing. Based on the findings of the analysis of the production process, it is recommended that mechanized techniques be employed in the operation and awareness training conducted to improve the understanding and skills of the brick manufacturers and to ensure production of good quality bricks. / NRF