• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 3
  • 2
  • 1
  • Tagged with
  • 10
  • 10
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies of the hydration of tricalcium silicate

Le Sueur, Philip J. January 1984 (has links)
The hydration reaction of tricalcium silicate and the various factors which influence it have been investigated using calorimetry, thermogravimetry, quantitative X-ray diffractometry, scanning and transmission electron microscopy and energy dispersive X-ray analysis. Various factors associated with the synthesis and subsequent storage of tricalcium silicate were found to alter its reactivity and it is thought that these may be responsible for much of the variability in the reported reactivity of tricalcium silicate preparations. The contribution of the individual factors (such as particle size distribution and impurity ion content) to such reactivity changes was investigated. Use of the Avrami equation to model the rate of heat output curves obtained by calorimetry was found to give good fits to the experimental data. Apparent activation energies of control and calcium chloride accelerated reactions were determined from the rate parameters derived from the fitting procedure. However, it is shown that the amount of mechanistic information which can be obtained from such a fitting procedure is limited. Observation of the detailed chemical and morphological changes occurring during the hydration of tricalcium silicate and the manner in which they are influenced by incorporation of calcium chloride (as a model accelerator) and sucrose (as a model retarder) show that during the later stages of hydration the chemistry of the reaction is not affected by the presence of the admixtures, but that their incorporation does cause some changes in the microstructure of the gel product.
2

Impactos e conflitos sócioambientais na comunidade do entorno da fábrica de cimento

Cajazeira, Maurício de Oliveira 15 March 2011 (has links)
The industrial sector causes the most damage to the enviroment, either by their production processes or production of polluting products, some having problems of disposal after use. There is some difficulty in combining industrial production growth with environmental preservation. The collective welfare depends increasingly on growth of output, bringing conflict in man's relationship with his environment. A cement factory was implanted in the town of Nossa Senhora do Socorro due to the discovery of a subsoil rich in raw material (limestone), supported by hopes of providing better economic and development to the municipality and the state of Sergipe, for job opportunities and local development through tax collection. The supply chain of construction impacts the environment in all stages of its process, so for the population of the municipality of Nossa Senhora do Socorro, in the relationship between capitalism and society, the problem is how to equate the contribution of the cement plant to the regional and local development, considering its size, representativeness in the state's economy and dealing with issues social and environmental. For this work, we use, surveys and bibliographic sources on research conducted in the study area and the main "actors" involved as research tools. Questionnaires were used which served as an exploratory tool and issues that were aimed to evaluate the positive and negative impacts on the economy of the city and the surrounding communities. With respect to the factory was observed the worksapce, the level of wages, treatment of issues related to health and worker safety. And finally, understanding the importance of sustainability in the manufacture of cement for the development of the town of Nossa Senhora do Socorro and Sergipe, recommendations are presented to the State, the Company and the Society. / O setor industrial é um dos que mais provoca danos ao meio ambiente, seja por seus processos produtivos ou pela fabricação de produtos poluentes e/ou que tenham problemas de disposição final após sua utilização. Existe uma certa dificuldade em associar o crescimento da produção industrial com a preservação ambiental. O bem-estar coletivo está condicionado cada vez mais ao crescimento da produção, trazendo desafetos na relação do homem com o seu meio ambiente. A fábrica de cimento foi implantada no município de Nossa Senhora do Socorro a partir da descoberta de um subsolo rico em matéria-prima (calcário), amparada pela expectativa de proporcionar melhores condições econômicas e de desenvolvimento ao município e ao estado de Sergipe com a oferta de empregos e o desenvolvimento local através da arrecadação de impostos. A cadeia produtiva da construção civil impacta o meio ambiente em todas as etapas de seu processo. Para a população do município de Nossa Senhora do Socorro, na relação capitalismo e sociedade, o problema é: como equacionar a contribuição da fábrica de cimento para o desenvolvimento regional e local, considerando seu tamanho, a representatividade na economia do estado e o tratamento das questões socioambientais. Para este trabalho, utilizamos como instrumentos de pesquisa, levantamentos em fontes bibliográficas e pesquisas efetuadas na área de estudo e nos principais stakeholders envolvidos. Foram aplicados questionários que serviram como instrumento exploratório e de levantamento de questões que tiveram como objetivo, avaliar os impactos positivos e negativos na economia do município e nas comunidades do entorno. Com relação à fábrica observou-se o ambiente de trabalho, o nível de salários, o tratamento das questões relacionadas à saúde e a segurança do trabalhador. E, ao final, entendendo a importância da sustentabilidade na fabricação de cimento para o desenvolvimento do município de Nossa Senhora do Socorro e para Sergipe, são apresentadas recomendações para boas práticas ao Estado, à Empresa e à Sociedade.
3

Sustainable Design and Operation of the Cement Industry

Avetisyan, Hakob G. 19 December 2008 (has links)
No description available.
4

Odloučení dopravního vzduchu surovinové moučky / Severance of raw material flour transportation air

Brzobohatý, Lukáš January 2013 (has links)
The dissertation is focused on the applied technical and economic analysis of the influence separation of transport air from raw meal on the economy clinker/cement production, in specific cement production. The analysis is performed on the basis of a detailed understanding and analysis of the function of each component of the technology of cement production, which are affected by separation of transport air from raw meal, mainly the dosing and preheat system of the raw meal. The results of the analysis show a significant effect (impact) separation of transport air on the production costs.
5

Využití odpadního tepla spalin pro výrobu elektrické energie / Utilization of waste heat from combustion gases for power production

Rejnuš, Vojtěch January 2015 (has links)
Methods of utilization waste heat are increasingly on the rise and can be applied in many technologies. One of the technologies is the manufacture of cement, which is focused issue of work. Within the solution, and for understanding the problem is outlined cement production process and the analysis of the waste heat from the process, on this basis are selected a suitable method using waste heat with a closer focus on ORC units. After following evaluation and selection of the most suitable unit is made design, calculation and construction of heat exchangers. The result is the evaluation of the entire proposal.
6

3D Geological Modelling of the Subsurface Adjacent to Cementa’s Quarry in Skövde, Sweden / Geologisk 3D modellering av närområdet till Cementas gruva i Skövde

Larsson, Minna January 2022 (has links)
Limestone is one of the main components of cement production. Limestone has been quarried in Skövde, Sweden, since the end of 19th century and Cementa AB has been operating the quarry since 1973. Aside from limestone, there are also Alum shale of Cambrian age, mudstones as well as bentonite layers of Ordovician age present in the quarry.  The production of cement evidently is important for Sweden’s infrastructure, and the quarry in Skövde is one of few known locations in the country with limestone with the right composition. Therefore, it is important to increase the knowledge regarding the character of the limestone to make accurate predictions for the future regarding the cement production. The geological knowledge of the area is already extensive; however, the aim of this thesis is to expand this knowledge further by constructing a 3D geological model. The data which has been used to construct the model are field observations, drill core data, chemical data, high-resolution pictures (photogrammetry) and resistivity measurements (field and samples). The resistivity measurements were done using the multiple gradient array, and apparent resistivity was inverted using Res2Dinv. The geological modelling was done using Leapfrog geo (© Seequent Systems, Incorporated). Two models have been proposed as a result of this project; one where high-grade limestone of lesser quality and whitestone has been regrouped with two other units (A) and one including all units (B). In the most recent drilling campaign, the nomenclature used to distinguish the units has been modified and does not differentiate high-grade limestone of lesser quality and whitestone from the rest. This affects coherence of the model and for this reason two models have been built. Both models show roughly flat lying units in the area of interest. Both low-grade limestone and lower waste stone units have consistent thickness in both models. The major difference between the models is how the high-grade limestone unit is modelled as a consequence of the additional units in model B. The result from the resistivity measurements shows unexpectedly low values, when compared to values from the literature as well as the measurements on hand samples from the quarry. The reason for these low values is still unclear, and therefore resistivity data has been used with caution. Considering this, it appears that resistivity measurements is not a suitable technique to characterize the subsurface in this particular area.  The models produced in this project provides information regarding thickness and extent of the units and overlying soil. As such, the new knowledge can be used to plan future prospecting campaigns, make projections, and estimates within current mining permits and evaluate how future mining can be conducted. / Kalksten är huvudkomponenten när det kommer till cementproduktion, vilken också behöver ha en specifik kemi för att vara lämplig att tillverka cement av. Kalksten av denna specifika kvalité har brutits i Skövde, Sverige, sedan slutet av 1800-talet. Cementproduktionen startade dock 1924 och Cementa köpte upp gruvan och fabriken 1973. I brottet finns förutom kalksten även alunskiffer, slamsten och bentonitlager. Vidare finns det två olika kvalitéer på kalkstenen, en med högt kalciumoxidvärde och en med lägre kalciumoxidvärde. Totalt representerar de formationer som finns i gruvan en 50 miljoner år lång historia av sedimentation. Cement utgör en grundläggande del för Sveriges infrastruktur, och brottet i Skövde är en av få platser i landet med en kalksten som har rätt kemi. Därmed är det viktigt att utöka kunskapen gällande karaktären på kalkstenslagren i och vid brottet för att kunna göra mer korrekta uppskattningar om Sveriges framtida cementproduktion. I dagsläget är kunskapen om geologin i och kring gruvan omfattande tack vare bland annat tidigare prospekteringskampanjer. Syftet med detta arbete är utöka den geologiska kunskapen ytterligare genom att konstruera en geologisk 3D modell. Denna geologiska 3D modell har skapats av data såsom borrhålsdata, resistivitetsmätningar samt drönarbilder för att bättre karakterisera de olika geologiska formationerna. På grund av att indelningen av de geologiska enheterna har varit olika mellan de tidigare prospekteringskampanjerna har två 3D modeller med olika upplösning skapats i stället för en. Modelleringen har fokuserats på ett område nordväst om nuvarande brytområde. Båda modellerna har sub-horisontella geologiska enheter inom intresseområdet. Vidare har modellerna liknande tjocklek och utbredning på enheterna i sin övre del, men skiljer sig åt längre ner. Detta på grund av att den ena modeller har flera enheter, vilket således även påverkar närliggande enheter. Dessa två modeller har utökat den geologiska kunskapen om området, till exempel de geologiska enheternas mäktighet och utbredning, samt hur mäktigt jordtäcket i området är. Denna nya kunskap kan användas för att planera och estimera hur brytning kan ske i framtiden. Det är dock viktigt att poängtera att det är modeller som skapats, vilka är antaganden av verkligheten.
7

Logística reversa para substituição de combustíveis na indústria cimenteira por coprocessamento em forno de clinquer

Junior, Nelson Kadel January 2012 (has links)
Submitted by William Justo Figueiro (williamjf) on 2015-07-10T22:43:09Z No. of bitstreams: 1 42b.pdf: 11938841 bytes, checksum: 548f5c4ae8b13931af52bc417ff2da4f (MD5) / Made available in DSpace on 2015-07-10T22:43:09Z (GMT). No. of bitstreams: 1 42b.pdf: 11938841 bytes, checksum: 548f5c4ae8b13931af52bc417ff2da4f (MD5) Previous issue date: 2012 / Nenhuma / O objetivo desta dissertação de mestrado é estudar um projeto de coprocessamento de resíduos, e desenvolver um meio de torná-lo sustentável economicamente, à luz das teorias sobre logística reversa. Este projeto traz consigo resultados que vão além da área financeira, ao utilizar, da melhor forma, as cadeias logísticas já existentes na região, reduzindo, assim, o seu impacto na natureza. Uma vez que este projeto foi identificado ainda na sua fase de desenvolvimento, o método de pesquisa utilizado foi a pesquisa-ação. Neste tipo de método, usam-se as teorias existentes para planejar as intervenções de campo, ao mesmo tempo que se aproveitam os resultados para gerar avanços teóricos. Os objetivos específicos deste trabalho buscam estudar, primeiramente, as empresas fornecedoras de resíduos, analisando as suas localizações, bem como os tipos de produtos disponibilizados. A partir daí, ver o melhor lugar para instalar a planta produtora de mistura (blend), levando em consideração as restrições ambientais, os custos envolvidos e a oferta de modais de transporte, e por fim, analisar as empresas cimenteiras consumidoras de tal mistura. Os resultados mais importantes estão relacionados à mudança de localização da planta de coprocessamento, ao processo logístico de coleta dos resíduos bem como do produto final e o desenvolvimento de uma embalagem para o seu transporte. As implicações finais são ambientais, financeiras e estratégicas. Este projeto viabiliza o uso de uma parte significativa de resíduos que antes teriam como destino, na melhor das opções, os aterros sanitários da região, e agora passam ser uteis como combustíveis em uma nova cadeia de produção. Já os resultados econômicos atingiram as duas principais empresas estudas. Para a primeira, houve uma redução de 27% no custo logístico dos produtos produzidos. Já para a segunda, 8% no custo de combustível utilizado em fornos. Por fim, as estratégicas garantem, para a unidade de blendagem, um diferencial perante possíveis novos entrantes no mercado. Para garantir tudo isso, esta pesquisa passa pelos conceitos de logística e logística reversa, fazendo um apanhado sobre a produção de cimento e relatando os combustíveis utilizados nestas plantas, com as suas futuras opções de substituição, uma vez que este é um tipo de indústria altamente demandante de energia e calor. Finalmente, o caso analisado é a primeira planta de coprocessamento do Rio Grande do Sul que fará uso de diversos tipos de resíduos na confecção de um combustível alternativo para fornos de clinquer. / This dissertation aims to study a waste co-processing, and develop a way to make it economically sustainable within the logistic and reverse logistics theory. This brings together results that go beyond the financial area, when the logistics chains in the region are used at best in order to reduce the impact on the environment. Once this research project has already been identified in its development phase, the method of research is action-research. In this type of method, they use existing theories to plan interventions in the field, while the results take advantage to generate theorist advancements. The specific aims of this paper target the study, firstly, of the waste suppliers, analyzing their locations as well as the kinds of available products. From this point of view, we can see the best place to install the production blend plant, taking into consideration the environmental restrictions, the costs and the offering of different types of transport, and finally it analyzes the cement consumer companies of such blend. The most important results are related to the changing of the co-processing plant location, the logistic process of waste collection as well as the final product and the development of a kind of suitable wrapping for its transport. The final consequences are environmental, financial and strategic. This project enables the use of a significant portion of waste that would previously have as destination, at best, the region's landfills, and are now being useful as fuels in a new production chain. Since the economic results achieved two major companies studied. For the first, there was a 27% reduction in logistics costs of products produced. As for the second, 8% of the cost of fuel. Finally, the strategic guarantee, for the blending unit, a differential to possible new entrants in the market. So, this study analyses the concepts on logistics and reverse-logistics, making an overview on the cement production and the different kinds of fuel used in these plants, with its future replacement options - once this is a type of industry that demands high amounts of energy and heating. Finally, the case study talks about the first co-processing plant in Rio Grande do Sul, which is going to use several sorts of waste in the manufacturing of an alternative kind of fuel for clinker kilns.
8

Studium možností separace chloridů z by-passových odprachů / Study on the possibilities of separation of chlorides from by-pass dust

Havelka, Jaroslav January 2017 (has links)
The thesis deals with the study and the characterization of bypass dusts from the cement plants. The aim of the thesis is to search for the possibilities of the usage of that secondary product by means of the cement production. The thesis focuses mainly on the determination of the amount of soluble substances in the dusts, the dependence of dissolution of the soluble share on water – dust ratio, the dependence of dissolution time on the yield of the soluble share and the influence of the temperature on the yield. The physical and chemical properties of the investigated samples taken from several cement plants in the Czech Republic and Slovakia were found out by using the following methods: by TG/DTA analysis, particles size by laser diffraction, phase composition of raw materials, treated raw materials and evaporation residues by X-ray diffraction. It was further investigated whether there was a link between finesse of the particles and the content of soluble substances (chlorides). This was accomplished by classification of the bypass dusts as fine and coarse fraction on the air cassifier with the target parameter X50 1 m. The aim of the classification was to find out whether some of the fractions carry majority share of some of components.
9

Mognadsmodell - Möjligheter inom industri 4.0 En förstudie på Cementa AB Slite / Maturity Model – Opportunities in Industry 4.0 a Preliminary Study at Cementa AB Slite

Olsson, Anton, Welltén, Johan January 2020 (has links)
Detta kandidatexamensarbete är en förstudie utfört på Cementa AB:s fabrik i Slite, Gotland, och grundar sig i att Cementa AB, Sveriges enda tillverkare av cement, står inför en omställning till helhetskonceptet Industri 4.0 som bygger på tekniker och principer för automation och digitalisering. Fabriken står även inför en hållbarhetsomställning, då branschen bidrar med stora koldioxidutsläpp genom sin tillverkning. Målet med kandidatexamensarbetet är att analyseravar Cementa AB står inför en Industri 4.0 omställning och även undersöka om det har någon koppling till deras hållbarhetsarbete. För att kunna avgöra utgångsläget för fabriken har studien konstruerat och använt sig av en mognadsmodell som bedömer vart företaget står inför en framtida omställning. Mognadsmodellen baseras på fem olika mognadsmodeller och innehåller dimensionerna Produktion, Teknik, Strategi, R&D, HR, Ledarskap, Kultur och Standardisering. Undersökningen av företagets mognad genomfördes med hjälp av en enkät, som distribuerades till fabrikens alla avdelningar. Svarsfrekvensen var på 82%. Enkätens frågor har svarsalternativ som är bedömda med poäng där lägst poäng innebär frånvaro av Industri 4.0 och högsta poäng innebär mognad inom Industri 4.0. Till varje dimensions mognad beräknades ett mognadsindex. Resultatet av enkäten analyserades med avseende på vardera dimensions avvikande mognadsobjekt för att belysa styrkor samt se potentialen inom varje dimension. Dimensionerna med lägst mognadsindex var HR och Strategi. Fabrikens totala mognad inom Industri 4.0 beräknas till nivån Existens som innebär att företaget har ett påbörjat arbete inom Industri 4.0 men saknar strategi, målbild och plan för vidare arbete. För att ytterligare belysa fabrikens möjligheter konstrueras en lista med de frågor som har störst potential. I denna lista belyses dimensionerna Strategi och Ledarskap som mest frekvent återkommande och med det anses arbetet med strategi och ledning fundamental för omställningens existens. Detta gäller även kopplingen till hållbarhetsarbetet, då ett tydligt fokus på hållbarhetsaspekterna kopplat med Industri 4.0-teknologier ger synergieffekter som hjälper varandra. Studien rekommenderar företaget i ett första skede att initiera en tvärfunktionell arbetsgrupp på ledningsnivå som har som uppgift att driva omställningen och fokuserar i ett första stadie på strategi och ledning. Sedan rekommenderar studien också att företaget i valfri ordning utvecklar enkäten för vidare uppföljning och kartläggning, jämföra sig med liknande fabriker, etablera samarbeten mellan företag, akademi och leverantörer, utforma en Roadmap för företaget och dess avdelningar samt fortsätta digitalisera verksamhetens system och strukturer. / This bachelor thesis is a case study that has been carried out at Cementa AB’s factory in Slite, Gotland, and targeted the Cementa AB’s future adaption to the concept Industry 4.0 which is based on techniques and principles for automation and digitalization. The factory is also facing a sustainability change, as the industry contributes to large carbon dioxide emissions through its manufacturing. The aim of the bachelor’s degree project is to analyze where Cementa AB is facing an Industry 4.0 transition and also to investigate whether it has any connection to their sustainability work. To be able to determine the starting position for the factory, the study has constructed and used a maturity model that assesses where the company is facing a future transition. The maturity model is based on five different maturity models and contains the dimensions Production, Technology, Strategy, R&D, HR, Leadership, Culture and Standardization. The study of the company's maturity was conducted by means of a survey, which was distributed to all the departments of the factory. The response rate was 82%. The survey's questions have response alternatives that are assessed with points where the lowest score means Absence of Industry 4.0 and highest score means Maturity within Industry 4.0. For each dimension maturity, a maturity index was calculated. The results of the survey were analyzed with respect to the different maturity objects of each dimension in order to highlight strengths and see the potential within each dimension. The dimensions with the lowest maturity index were HR and Strategy. The factory's total maturity in Industry 4.0 is calculated to the Existence level, which means that the company has started work in Industry 4.0 but lacks strategy, goals and plans for further work. To further clarify the factory's possibilities, a list of the issues with the greatest potential is constructed. In this list, the dimensions Strategy and Leadership are highlighted as the most frequent recurring, and with this the work with strategy and leadership is considered fundamental to the existence of the transition. This also applies to the link to sustainability work, as a clear focus on the sustainability aspects linked to Industry 4.0 technologies produces synergies that help each other. The study recommends the company, in a first stage, to initiate a cross-functional working group at management level which has the task of driving the transition and focuses in a first stage on strategy and management. The study also recommends that the company in any arrangements develops the survey for further follow-up and mapping, compares itself with similar factories, establishes collaborations between companies, academia and suppliers, design a roadmap for the company and its departments, and continue to digitize the company's systems and structures.
10

Improving climate performance of cement production : Developing an assessment framework and applying it to a CEMEX cement production cluster in Germany

Feizaghaei, Roozbeh January 2011 (has links)
It is very likely that human being is contributing to the process of global warming. Industrial activities such as cement production are among the largest sources of human-induced greenhouse gas emissions. Therefore, there are ongoing efforts to reduce the CO2 emissions attributed to the cement production. In order to be able to systematically identify, classify, and evaluate the most effective, applicable, and feasible CO2 improvement measures, it is essential to have an assessment framework, which has an environmental management perspective. Such a framework should be able to cover the widest range of potential CO2 improvement measures, therefore it has to have a wide system perspective and consider all material, and energy flows within the industry as useful resources. The first part of this thesis uses the concepts of Industrial Ecology and Industrial Symbiosis as the supporting theoretical concepts for developing such assessment framework. The framework has semi-qualitative approach for assessing different measures and is developed in two parts: (1) generic and (2) site-specific assessment. The first part considers general aspects of the measures such as level of Industrial Symbiosis (i.e. complexity of business approach), the potential of each measure for reducing CO2 emissions, and their technological maturity. The second part assesses the feasibility of the measures regarding the conditions of a specific cement producing system. Aspects such as organizational applicability, technical and infrastructural applicability, and the existing level of implementation of each measure are considered. In the second part of this thesis, the developed framework is applied on a selected cement production system which is a cluster composed of three cement plants in Germany (owned by CEMEX) referred to as the Cluster West. The result of the assessment provides insights about the state-of-the-art of CO2 improvement measures in cement industry in general and also demonstrates which of these measures are most (or least) suited for development in the Cluster West. The production system of the Cluster West has effectively applied CO2 improvement measures in areas such as producing blended cement products, using alternative fuels (and renewable fuels) for clinker production. In addition, its clinker production (the Kollenbach plant that is part of the Cluster West) has relatively good energy efficiency. According to the results of the assessment, CO2 improvement measures such as co-generation (producing electricity from excess heat of the plant), using renewable fuels, using alternative materials for clinker production, and increasing the usage of alternative fuels are among the most applicable choices for further implementation. / In relation with LIU-CEMEX Indsutrial Ecology project (2011)

Page generated in 0.1138 seconds