M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology / Corrosion responses of some carbon steels, stainless steel and copper alloys in the presence of a culture of bacteria (referred to as SRB-Sulphate-reducing bacteria) found in industrial heat exchangers, was studied to recommend best alloys under this service condition, with techno-economic consideration. Water from cooling towers in three plants in a petrochemical processing complex were analysed for SRB presence. Two of the water samples showed positive indication of SRB presence. The mixed cultures obtained from plant one were grown in prepared media and incubated at 35 °C for 18 days. Potentiodynamic polarisation studies in anaerobic conditions were done on the selected alloys in aqueous media with and without the grown SRB. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were then used to study the corrosion morphology and corrosion products formation. The voltamograms show higher icorr for alloys under the SRB compared to the control media, indicating the SRB indeed increased the corrosion rates. The surface analysis showed pitting on steel alloy ASTM A106-B. Localised attack to the grain boundaries on a selective area, was seen on ASTM A516-70 dislodging the grains, and intergranular corrosion was seen throughout the exposed area of ASTM A179. Copper alloys showed pitting on ASTM B111 grade C71500 (70-30), and denickelification on ASTM B111 grade C70600 (90-10), and is a good alternative material for use apart from carbon steel alloys, recording a low corrosion rate of 0.05 mm/year. The EDS analysis supported the findings showing higher weight percent of iron and sulphur on surface of the alloys after exposure to the SRB media. This implies that the presence of the sulphur ion indeed increased the corrosion rate. ASTM A516-70 carbon steel was chosen as a suitable alternative material to the stainless steel in this environment. The Tafel plot recorded a corrosion rate of 1.08 mm/year for ASTM A516-70 when exposed to SRB media.

The objective of this diploma thesis is to describe nowadays almost forgotten events in France during the Second World War, when the historical statues and monuments from the Third Republic in France are irretrievably destroyed because of melting non-ferrous metals used for arms-production in Nazi Germany. The key goal of the thesis is to mention some of the main decisions that led to the destruction of certain works and on the basis of that analysis consider to what extent the occupier contributed to their loss and to what extent their removal was inevitable. Within historical context, the first chapter introduces the period and ideas of the Third Republic until the arrival of the Vichy régime with its new ideals. The second chapter mentions expansion of sculpture of the Third Republic and statuomania. The development of the campaign for collection of non-ferrous metals and its actors are discussed in the third chapter. Afterwards this work presents specific decisions about the destruction of statues, based on religious, political and aesthetic subtext. In the fifth chapter in practical part, the thesis tries to analyze these decisions and to determine the cause of the elimination of statues based on the decisions. The last part focuses on the different generals reactions to destruction of the...

>Magister Scientiae - MSc / A comparative study of electrolysers using different anodic materials for the electrolysis of brine (sodium chloride) for the production of sodium hypochlorite as a source of A comparative study of electrolysers using different anodic materials for the electrolysis of brine (sodium chloride) for the production of sodium hypochlorite as a source of available chlorine for disinfection of rural water supplies has been undertaken. The electrolyser design used was tubular in form, having two chambers i.e. anode inside and cathode outside, separated by a tubular inorganic ceramic membrane. The anode was made of titanium rod coated with a thin layer of platinum and a further coat of metal oxide. The cathode was made of stainless steel wire. available chlorine for disinfection of rural water supplies has been undertaken. The electrolyser design used was tubular in form, having two chambers i.e. anode inside and cathode outside, separated by a tubular inorganic ceramic membrane. The anode was made of titanium rod coated with a thin layer of platinum and a further coat of metal oxide. The cathode was made of stainless steel wire. An assessment of these electrolysers was undertaken by studying the effects of some variable parameters i.e. current, voltage and sodium chloride concentration. The flow rate was kept unchanged at 50ml/h anolyte and 140ml/h catholyte since it was found to be optimum flow rate for chlorine generation. Figures of merit of the electrolysers were calculated on the basis of three sets of measurements. Analytical methods used for the determination of sodium hypochlorite concentration were iodometric and N, N-Diethyl-p- Phenylenediamine (DPD) titration methods. The DPD titration method was used to determine the chlorine concentration of less than 1mg/L, while the iodometric titration method was used to determine chlorine concentration of ImgIL and above. Sodium chlorate present in the hypochlorite solution was also determined using a spectrophotometric method. The cobalt oxide electrolyser has been shown to be superior as compared to the ruthenium dioxide and manganese dioxide electrolysers in terms of hypochlorite generation. Sodium chlorate was present but at concentration levels not hazardous for use in dosing water for drinking purposes. Analysis of hydroxyl radicals was undertaken since there were claims that these are produced during brine electrolysis. Hydroxyl radical analysis was not successful, since sodium hypochlorite and hypochlorous acid interfere using the analytical method described in this study.

No description available.

In modern conditions, the effective development of industrial enterprises is complicated by the low organizational and technical level of production, high costs and insufficient financial resources, which requires the active attraction of investment funds. The purpose of the master's thesis is to develop a methodological approach to the formation of the investment policy of a non-ferrous metallurgy enterprise within the framework of Industry 4.0. The research considers the concept of the investment policy of the enterprise and the correlation of the investment activity of the enterprise with the implementation of technologies of Industry 4.0. The sources used were teaching and research literature, the results of empirical research of the author and corporate statistics. In the master's thesis, the author’s methodology for the selection of investment projects was developed as part of the investment policy of an industrial non-ferrous metallurgy enterprise, which includes three stages of selection: preliminary, coefficient, final. The application of this technique allows you to deepen the analysis and assessment of the effectiveness of investment projects related to Industry 4.0. / В современных условиях эффективное развитие промышленных предприятий осложняется низким организационно-техническим уровнем производства, высокими затратами и недостаточными финансовыми ресурсами, что требует активного привлечения инвестиционных средств. Целью магистерской диссертации является разработка методического подхода к формированию инвестиционной политики предприятия цветной металлургии в рамках «Индустрии 4.0». В работе рассматривается понятие инвестиционной политики предприятия и вопросы взаимосвязи инвестиционной деятельности предприятия с внедрением технологий «Индустрии 4.0». В качестве источников использовалась учебно-методическая и научно-исследовательская литература, результаты эмпирических исследований автора и данные корпоративной статистики. В магистерской диссертации была разработана авторская методика отбора инвестиционных проектов в рамках инвестиционной политики промышленного предприятия цветной металлургии, включающая в себя три этапа отбора: предварительный, коэффициентный, заключительный. Применение данной методики позволяет углубить анализ и оценку эффективности инвестиционных проектов, связанных с «Индустрией 4.0».

Современные условия хозяйственной деятельности, ее динамика делают рационализацию процессов материально-технического обеспечения одним из основных конкурентных преимуществ хозяйствующих субъектов. Данное положение особенно актуально для материалоемких малых предприятий занятых в цветной металлургии. Целью магистерской диссертации является разработка методики обеспечения малых промышленных предприятий ломом цветных металлов. В работе анализируются основные производственные особенности малых промышленных предприятий в разрезе этапов ресурсного обеспечения предприятий, даются рекомендация по оптимизации ресурсного обеспечения малого промышленного предприятия ломом цветных металлов. Отмечено особое значение рынка вторичных металлов, как потенциального источника экономии ресурсов для материалоемких малых промышленных предприятий. В качестве источников использовалась учебно-методическая и научно-исследовательская литература, результаты исследований автора. В магистерской диссертации была разработана методика обеспечения малых промышленных предприятий ломом цветных металлов, в основу которой положен учет специфики хозяйственной деятельности, возможностей производства, оценки поставщиков и факторе времени, что позволяет снизить затраты на основные материалы, а также сосредоточить внимание на возможных точках развития вертикальной (обратной) интеграции, тем самым перейти на качественно новую основу ресурсного обеспечения. / Modern conditions of economic activity, its dynamics make the rationalization of the processes of material and technical support one of the main competitive advantages of economic entities. This provision is especially relevant for material-intensive small enterprises engaged in non-ferrous metallurgy. The aim of the master's thesis is to develop a methodology for providing small industrial enterprises with non-ferrous scrap. The paper analyzes the main production features of small industrial enterprises in the context of the stages of resource provision of enterprises, gives a recommendation for optimizing the resource provision of a small industrial enterprise with non-ferrous scrap. The special importance of the secondary metals market as a potential source of resource saving for material-intensive small industrial enterprises is noted. Educational-methodical and research literature, the results of the author's research were used as sources. In the master's thesis, a methodology was developed for providing small industrial enterprises with non-ferrous scrap, which is based on taking into account the specifics of economic activity, production capabilities, assessing suppliers and the time factor, which allows reducing the cost of basic materials, as well as focusing on possible points of development of vertical (reverse) integration, thereby moving to a qualitatively new basis of resource provision.

[pt] Sabe-se que o coagulante sulfato férrico pode ser obtido através da reação de oxidação entre sulfato ferroso e peróxido de hidrogênio em meio ácido. Porém, o método conhecido de obtenção deste coagulante em escala industrial utilizando o peróxido de hidrogênio como agente oxidante não proporciona condições economicamente atrativas, frente aos demais processos. Este potente agente oxidante sofre forte influência da temperatura e da presença de íons ferro no seu processo de auto decomposição em água e oxigênio. Pode-se considerar que as condições do meio reacional, na etapa de adição do agente oxidante, são os fatores determinantes para a produção do coagulante férrico com o maior aproveitamento do peróxido de hidrogênio adicionado. O presente trabalho teve como objetivo investigar as condições necessárias para a produção do coagulante férrico utilizando o peróxido de hidrogênio, em um processo economicamente competitivo. A pesquisa foi fundamentada nas técnicas de planejamento de experimentos e otimização de processos. A modelagem matemática do processo possibilitou a definição da magnitude dos parâmetros a serem utilizados otimizando o processo e a especificação das características desejadas do produto final. As variáveis independentes estudadas na modelagem matemática foram: temperatura (7,5 – 27,5 graus celsius), quantidade de peróxido de hidrogênio (100 – 300 porcento) referente à sua quantidade estequiométrica e a diluição do meio utilizando água (100 – 300 porcento) referente à sua quantidade estequiométrica. As quantidades estequiométricas dos reagentes foram determinadas visando ao atingimento das especificações de um coagulante férrico comercial. O modelo desenvolvido foi sobre a Conversão de Fe2(+) em Fe3(+) (porcento) e avaliado através da Análise da Variância (ANOVA). As condições ótimas escolhidas para o ponto ótimo foram: temperatura igual a 17,5 graus celsius, 150 porcento da quantidade estequiométrica de peróxido de hidrogênio e 200 porcento da quantidade estequiométrica de água. A resposta da etapa de otimização indicou uma conversão de 96,17 porcento de Fe2(+) em Fe3(+), resultando em um coagulante dentro dos padrões especificados por norma técnica. O modelo matemático obtido previu uma conversão de 96,13 porcento de Fe2(+) em Fe3(+), resultando em um erro percentual de 0,043 porcento entre o resultado predito pelo modelo matemático e o resultado experimental. As análises das superfícies de resposta e da quantidade de peróxido de hidrogênio residual em solução indicaram que o controle do processo em baixas temperaturas contribui para o melhor aproveitamento do peróxido de hidrogênio na conversão de Fe2(+) em Fe3(+), devido à desaceleração da auto decomposição incitada pelo fator temperatura. A análise do potencial de redução ao longo da reação em função do perfil de conversão mostrou que conversões acima de 90 porcento de Fe2(+) em Fe3(+) apresentaram potencial redox (Eh) correspondente acima de 0,70 Volts, indicando a possibilidade da utilização deste parâmetro no controle da conversão em processos industriais. / [en] It is known that the coagulant ferric sulfate can be obtained by the oxidation reaction of ferrous sulfate with hydrogen peroxide in acidic medium. However, the known method of obtaining this coagulant on an industrial scale using hydrogen peroxide as an oxidizing agent do not provide economically attractive conditions compared to other processes. This potent oxidizing agent undergoes strong influence of the temperature and the presence of iron ions in its process of self-decomposition in water and oxygen. It can be considered that the conditions of the reaction medium in the step of adding the oxidizing agent are the determining factors for the production of the ferric coagulant with the greatest use of the added hydrogen peroxide. The present work had the objective of investigating the necessary conditions for the production of the ferric coagulant using the hydrogen peroxide as an economically competitive process. The research was based on the techniques of factorial design and process optimization. The mathematical modeling of the process allowed the definition of the magnitude of the parameters to be used, optimizing the process and specifying the desired characteristics of the final product. The independent variables studied in the mathematical modeling were: temperature (7,5 – 27,5 celsius degrees), amount of hydrogen peroxide (100-300 percent) relative to its stoichiometric amount, and dilution of the medium using water (100-300 percent) relative to its stoichiometric amount. The stoichiometric quantities of the reactants were determined in order to reach the specifications of a commercial ferric coagulant. The model developed was on Conversion of Fe2(+) to Fe3(+) (percent) and evaluated through Analysis of Variance (ANOVA). The optimum conditions chosen for the optimum were: temperature equal to 17,5 Celsius degrees, 150 percent of the stoichiometric amount of hydrogen peroxide and 200 percent of the stoichiometric amount of water. The optimization of the response surfaces indicated a conversion of 96.17 percent Fe2(+) to Fe3(+), resulting in a coagulant within the characteristics specified by the technical standard. The obtained mathematical model predicted a conversion of 96.13 percent Fe2(+) to Fe3(+), resulting in a percentage error of 0,043 percent between the predicted results by the mathematical model and the experimental results. The analysis of the response surfaces and the amount of residual hydrogen peroxide in solution indicated that the control of the process at low temperatures contributes to the better utilization of the hydrogen peroxide in the conversion of Fe2(+) into Fe3(+), due to the deceleration of the self-induced decomposition by the factor temperature. The analysis of the reduction potential along the conversion profile function showed that conversions above 90 percent of Fe2(+)into Fe3(+) presented a corresponding redox potential (Eh) above 0,70 Volts, indicating the possibility of using this parameter for the control of conversion into industrial processes.

The threat posed by non-ferrous metal theft to industries in South Africa is substantial but is also regarded with indifference. A reason for this view may be that the criminal act is ordinarily not accompanied by violence and the target of the crime is an object that is far removed from the vicinity of the majority of South Africans. Non-ferrous metal theft may sometimes even be erroneously termed a victimless crime. This study endeavours to shed light on the complexities of non-ferrous metal theft and the industrial dangers that may be suffered if this crime is not eradicated. A case study from the mining industry was used to examine the nature and extent of non-ferrous metal theft. A mixed methods approach was followed in terms of which qualitative and quantitative research was done sequentially to provide the best possible representation of the situation. The participant allowed access to data over a six-year period as well as access to mine employees for interviews to assist with understanding the safety and security measures that the mine put in place to protect its workforce. This information led to another realisation, namely that if non-ferrous metal thieves cut an electricity supply line that is critical for life support and transportation in the mine, mineworkers may succumb to the harsh conditions underground. It also became evident that the police and the criminal justice system must develop a better understanding of the seriousness of non-ferrous metal theft. If this does not happen in the near future, managing the consequences of nonferrous metal theft at South African mines will become a mammoth task. Such mines and other industries affected by non-ferrous metal related theft must collaborate with each other and the police in order to understand the nature of the crime and to ensure that the prosecution of the perpetrators is handled properly. These industries should also subscribe to a pragmatic approach to crime prevention whereby various components from different crime prevention strategies are used to address the issues being experienced and whereby a unique crime prevention model for each industry and mining site can be developed. / Police Practice / M.A. (Policing)

O objetivo deste trabalho foi desenvolver potenciais materiais para aplicações automotivas, em particular como insertos para assento de válvula em motores de combustão interna à gasolina. O desenvolvimento compreendeu as etapas de processamento dos materiais via metalurgia do pó, tratamento térmico, caracterização microestrutural e mecânica, usinagem e desgaste dos mesmos. O desenvolvimento objetivou principalmente a redução de custo e a aplicação de elementos menos poluentes, excluindo-se, por exemplo, a aplicação do Co devido ao seu alto custo e do Pb devido aos seus efeitos toxicológicos e prejudiciais ao meio ambiente. A realização de uma pesquisa minuciosa na busca de patentes relacionadas indicou que os materiais estudados apresentam composições particulares, e, portanto inéditas. Os resultados encontrados nos ensaios de dureza e de resistência à compressão radial nas amostras tratadas termicamente apresentaram resultados superiores aos da liga comercial atualmente em uso. Testes de usinabilidade em amostras sem tratamento térmico apresentaram comportamento similar ao da liga comercial, indicando que a usinabilidade do material praticamente não foi afetada com a mudança na composição química. Após a etapa de tratamento térmico, as ligas obtidas apresentaram valores de esforços de corte superiores aos do material comercial. Os resultados dos testes de desgaste abrasivo em amostras tratadas termicamente apresentaram menores valores de coeficientes de atrito e perda de massa em todos os casos em relação ao material comercial. Este comportamento é devido aos benefícios introduzidos pelo tratamento térmico executado e pela adição de alguns elementos resistentes ao desgaste na forma de carbonetos de Nb e Ti/W. Os resultados dos esforços de corte apresentaram boa concordância com os resultados dos ensaios de desgaste. Os materiais produzidos apresentam-se como potenciais candidatos para substituir, com vantagens, inserto para assento de válvula a base de Fe-Co em motores de combustão interna a gasolina. / The aim of this work was the development of materials for automotive applications, in particular, valve seat inserts for gasoline combustion engines. The development involved the following activities: processing by powder metallurgy techniques, heat treatment, mechanical and microstructural characterization, machining and wear of materials. This work was undertaken aiming cost reduction of this component by the use of cheaper and less pollutant elements, eliminating the presence of Co and Pb due to their high cost and toxicological effects, respectively. The accomplishment of a thorough research into patents revealed that the materials studied here present particular compositions and were not yet produced. The results of hardness measurements and the transverse radial strength of the studied materials, after heat treatment, revealed superior properties than the commercial alloys applied at the moment. The machining tests of the material without heat treatment indicated a similar behaviour in comparison to the commercial alloy, suggesting that the new alloy chemistry composition was not deleterious in this sense. After heat treatment, the obtained alloys presented a cutting force increase in relation to the commercial alloy. Wear tests results of heat treated materials presented smaller friction coefficient and mass loss than the commercial alloy, in all cases. This was especially achieved due to the advantages offered by heat treatment allied to the addition of NbC and Ti/W carbides. The materials obtained here showed to be potential candidates to substitute with advantages, valve seat inserts made of Fe-Co alloys for gasoline combustion engines.

O objetivo deste trabalho foi desenvolver potenciais materiais para aplicações automotivas, em particular como insertos para assento de válvula em motores de combustão interna à gasolina. O desenvolvimento compreendeu as etapas de processamento dos materiais via metalurgia do pó, tratamento térmico, caracterização microestrutural e mecânica, usinagem e desgaste dos mesmos. O desenvolvimento objetivou principalmente a redução de custo e a aplicação de elementos menos poluentes, excluindo-se, por exemplo, a aplicação do Co devido ao seu alto custo e do Pb devido aos seus efeitos toxicológicos e prejudiciais ao meio ambiente. A realização de uma pesquisa minuciosa na busca de patentes relacionadas indicou que os materiais estudados apresentam composições particulares, e, portanto inéditas. Os resultados encontrados nos ensaios de dureza e de resistência à compressão radial nas amostras tratadas termicamente apresentaram resultados superiores aos da liga comercial atualmente em uso. Testes de usinabilidade em amostras sem tratamento térmico apresentaram comportamento similar ao da liga comercial, indicando que a usinabilidade do material praticamente não foi afetada com a mudança na composição química. Após a etapa de tratamento térmico, as ligas obtidas apresentaram valores de esforços de corte superiores aos do material comercial. Os resultados dos testes de desgaste abrasivo em amostras tratadas termicamente apresentaram menores valores de coeficientes de atrito e perda de massa em todos os casos em relação ao material comercial. Este comportamento é devido aos benefícios introduzidos pelo tratamento térmico executado e pela adição de alguns elementos resistentes ao desgaste na forma de carbonetos de Nb e Ti/W. Os resultados dos esforços de corte apresentaram boa concordância com os resultados dos ensaios de desgaste. Os materiais produzidos apresentam-se como potenciais candidatos para substituir, com vantagens, inserto para assento de válvula a base de Fe-Co em motores de combustão interna a gasolina. / The aim of this work was the development of materials for automotive applications, in particular, valve seat inserts for gasoline combustion engines. The development involved the following activities: processing by powder metallurgy techniques, heat treatment, mechanical and microstructural characterization, machining and wear of materials. This work was undertaken aiming cost reduction of this component by the use of cheaper and less pollutant elements, eliminating the presence of Co and Pb due to their high cost and toxicological effects, respectively. The accomplishment of a thorough research into patents revealed that the materials studied here present particular compositions and were not yet produced. The results of hardness measurements and the transverse radial strength of the studied materials, after heat treatment, revealed superior properties than the commercial alloys applied at the moment. The machining tests of the material without heat treatment indicated a similar behaviour in comparison to the commercial alloy, suggesting that the new alloy chemistry composition was not deleterious in this sense. After heat treatment, the obtained alloys presented a cutting force increase in relation to the commercial alloy. Wear tests results of heat treated materials presented smaller friction coefficient and mass loss than the commercial alloy, in all cases. This was especially achieved due to the advantages offered by heat treatment allied to the addition of NbC and Ti/W carbides. The materials obtained here showed to be potential candidates to substitute with advantages, valve seat inserts made of Fe-Co alloys for gasoline combustion engines.