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Naftos krekinge naudotas katalizatorius yra ceolitinė medžiaga, kurios unikalios savybės mažai išnaudojamos cementinių medžiagų gamybos technologijoje. Ugniai atspariuose betonuose naudojami įvairūs priedai-modifikatoriai yra labai brangūs, todėl naudoto katalizatoriaus panaudojimas, kaip modifikuojančio betono savybes priedo, turi ne tik ekologinį (atliekų utilizavimas) bet ir ekonominį pagrindą. Vykdant šį darbą sukurti vidutinio cemento kiekio ugniai atsparūs šamotbetoniai su 70 % ir 40 % aliuminio oksido turinčiais aliuminatiniais cementais ir naudoto katalizatoriaus priedu atitinkamai 2,5 % ir 5,0 %. Darbe taip pat atskleistas efektyvus katalizatoriaus poveikis aliuminatinio cemento hidratacijai, cemento akmens struktūros susidarymui kietėjimo metu ir jos pokyčiams veikiant aukštoms temperatūroms. / Fluidized bed catalytic cracking catalyst waste is a zeolite material. Its unique properties are underused in cementitious materials production technology. Various additives, modifiers used in refractory castables are very expensive, so the use of catalyst waste as a modifying additive of castable properties has not only an ecological (waste recycling) but also an economical basis. Medium cement refractory castable was developed using 70 % and 40 % of aluminium oxide containing aluminate cement and catalyst waste additive, respectively 2,5 % and 5,0 %. The work also reveals an efficient effect of catalyst waste on alumina cement hydration, structure formation during cement solidification and after treatment at high temperature.

Fluidized bed catalytic cracking catalyst waste is a zeolite material. Its unique properties are underused in cementitious materials production technology. Various additives, modifiers used in refractory castables are very expensive, so the use of catalyst waste as a modifying additive of castable properties has not only an ecological (waste recycling) but also an economical basis. Medium cement refractory castable was developed using 70 % and 40 % of aluminium oxide containing aluminate cement and catalyst waste additive, respectively 2,5 % and 5,0 %. The work also reveals an efficient effect of catalyst waste on alumina cement hydration, structure formation during cement solidification and after treatment at high temperature. / Naftos krekinge naudotas katalizatorius yra ceolitinė medžiaga, kurios unikalios savybės mažai išnaudojamos cementinių medžiagų gamybos technologijoje. Ugniai atspariuose betonuose naudojami įvairūs priedai-modifikatoriai yra labai brangūs, todėl naudoto katalizatoriaus panaudojimas, kaip modifikuojančio betono savybes priedo, turi ne tik ekologinį (atliekų utilizavimas) bet ir ekonominį pagrindą. Vykdant šį darbą sukurti vidutinio cemento kiekio ugniai atsparūs šamotbetoniai su 70 % ir 40 % aliuminio oksido turinčiais aliuminatiniais cementais ir naudoto katalizatoriaus priedu atitinkamai 2,5 % ir 5,0 %. Darbe taip pat atskleistas efektyvus katalizatoriaus poveikis aliuminatinio cemento hidratacijai, cemento akmens struktūros susidarymui kietėjimo metu ir jos pokyčiams veikiant aukštoms temperatūroms.

Os concretos refratários são materiais que apresentam estrutura complexa contendo uma fração de partículas finas (D < 100?m) chamada de matriz e outra mais grosseira da ordem de até centímetros compostas por agregados. Dentre as propriedades importantes durante a aplicação dos concretos refratários, este trabalho aborda principalmente a energia de fratura e a resistência à erosão. Para a avaliação dessas propriedades vários estudos vêm sendo desenvolvidos nos últimos anos. A introdução do método da cunha para propagação estável da trinca é um exemplo, pois este método é utilizado para materiais com estrutura grosseira, como é o caso dos concretos. Já em se tratando de resistência a erosão, pouco se encontra na literatura a respeito desse assunto para concretos refratários. Tendo em vista a aplicação destes materiais, foi avaliado o comportamento da energia de fratura e resistência à erosão de concretos refratário aluminoso convencional antierosivo utilizado na indústria petroquímica com o objetivo de correlacionar os resultados de energia de fratura e a resistência à erosão. Para o desenvolvimento do trabalho foram usados dois concretos a com mesma composição química, variando somente o tamanho de agregado. Foram avaliadas além da energia de fratura e da resistência à erosão outras propriedades foram avaliadas como: os módulos elástico e de ruptura, porosidade aparente, fases cristalinas e microestrutura, e ainda foi realizado um estudo da matriz do concreto. Os resultados mostraram que a energia de fratura aumenta com o aumento do tamanho de agregado para o concreto estudado e a resistência a erosão aumenta com a temperatura de tratamento térmico devido a ceramização da matriz, conforme análise das imagens. Em função dos resultados, pode-se concluir que não foi observada uma boa correlação entre energia de fratura e resistência à erosão. Mas esta correlação de energia de fratura e de resistência à erosão pode ter o mesmo comportamento que a correlação entre comprimento característico e resistência á erosão para faixas específicas de tamanho de agregado. / Castables materials are known to be formed by a complex microstructure containing a fine fraction known as matrix (D<100?m) and another one known as aggregate containing thicker particles up to centimeters in size. Among its most notable properties regarding application, this research primarily addresses to the fracture energy and its erosion resistance. In recent years, some studies have been performed concerning such assessments. As an example, the wedge splitting procedure has been applied in the stable crack propagation method used for some thicker structured materials evaluation such the castables ones. On the other hand, a few data have been gathered concerning castable\'s erosion resistance. Facing such applications the main goal was the study of conventional aluminous anti erosive castables once it has been used in the petrochemical industry in order to correlate fracture energy and erosion resistance results. On this research, two castables samples with the same chemical composition were tested differing only its aggregate particle grain sizes. Besides fracture energy and erosion resistance, other important properties were evaluated as following: elastic modulus, rupture modulus, apparent porosity, crystalline phases and a castable matrix study was also carried out. The results demonstrate an increase on fracture energy as the studied castable aggregate size also increases and according to images studied, the erosion resistance suffers another increment regarding the thermal treatment temperature increase due matrix ceramization. Based on the obtained results, it can be concluded that no observation was made regarding the fracture energy and erosion resistance but it may exist an energy correlation between them once there is some observed between the characteristic length and the erosion resistance concerning the aggregate size range.

A constante busca por redução de custos e alternativas estratégicas por abastecimento de insumos refratários, tem levado as usinas siderúrgicas à buscar novos fornecedores para atender suas necessidades. Com base na necessidade da Companhia Siderúrgica Nacional (CSN), firmou-se uma parceria entre universidade e empresa, com intuito de desenvolver um novo fornecedor para um insumo refratário o qual só era fornecido por uma empresa. Foi então iniciado um trabalho de investigação das propriedades físico-químicas do material utilizado pela CSN (material de referência), utilizando-se a análise da distribuição granulométrica, composição mineralógica e propriedades mecânicas. A partir deste ponto, convidouse uma empresa genuinamente nacional, para desenvolver um novo produto, com matérias primas nacionais, que tivesse as mesmas propriedades mecânicas do material de referência. O concreto nacional foi caracterizado da mesma forma que o material de referência, em suas propriedades físico-químicas e ensaios mecânicos. Com base nos resultados foi realizado um teste em escala piloto, com aprovação do material. A empresa parceira passou a ter um novo material em sua carteira de produtos comercializado no mercado nacional e a CSN está realizando testes em escala industrial para aprovar um novo fornecedor de concreto refratário de alta resistência mecânica. / The constant search for cost reduction and strategic alternatives for refractory raw materials supply, has led the steelplants to look for new suppliers to meet its needs. Companhia Siderurgica Nacional (CSN) has signed a partnership between universities and companies, aiming to develop a new supplier for a refractory raw material which was only supplied by one company. Then a research based on chemical-physical properties of material used by CSN (reference material) was started, using the analysis of particle size distribution, mineralogical composition and mechanical properties. From this point, a genuine national company was invited, to develop a new product, with national raw materials, which had the same mechanical properties of the reference material. The national castable was characterized in the same way as the reference material in their chemical-physical properties and mechanical tests. Based on the results a test was performed on a pilot scale, with the approval of the material. The partner company has taken on a new material in its portfolio of products marketed in the domestic market and CSN is conducting tests on an industrial scale to approve a new supplier of refractory concrete with high mechanical strength.

A constante busca por redução de custos e alternativas estratégicas por abastecimento de insumos refratários, tem levado as usinas siderúrgicas à buscar novos fornecedores para atender suas necessidades. Com base na necessidade da Companhia Siderúrgica Nacional (CSN), firmou-se uma parceria entre universidade e empresa, com intuito de desenvolver um novo fornecedor para um insumo refratário o qual só era fornecido por uma empresa. Foi então iniciado um trabalho de investigação das propriedades físico-químicas do material utilizado pela CSN (material de referência), utilizando-se a análise da distribuição granulométrica, composição mineralógica e propriedades mecânicas. A partir deste ponto, convidouse uma empresa genuinamente nacional, para desenvolver um novo produto, com matérias primas nacionais, que tivesse as mesmas propriedades mecânicas do material de referência. O concreto nacional foi caracterizado da mesma forma que o material de referência, em suas propriedades físico-químicas e ensaios mecânicos. Com base nos resultados foi realizado um teste em escala piloto, com aprovação do material. A empresa parceira passou a ter um novo material em sua carteira de produtos comercializado no mercado nacional e a CSN está realizando testes em escala industrial para aprovar um novo fornecedor de concreto refratário de alta resistência mecânica. / The constant search for cost reduction and strategic alternatives for refractory raw materials supply, has led the steelplants to look for new suppliers to meet its needs. Companhia Siderurgica Nacional (CSN) has signed a partnership between universities and companies, aiming to develop a new supplier for a refractory raw material which was only supplied by one company. Then a research based on chemical-physical properties of material used by CSN (reference material) was started, using the analysis of particle size distribution, mineralogical composition and mechanical properties. From this point, a genuine national company was invited, to develop a new product, with national raw materials, which had the same mechanical properties of the reference material. The national castable was characterized in the same way as the reference material in their chemical-physical properties and mechanical tests. Based on the results a test was performed on a pilot scale, with the approval of the material. The partner company has taken on a new material in its portfolio of products marketed in the domestic market and CSN is conducting tests on an industrial scale to approve a new supplier of refractory concrete with high mechanical strength.

Among the most impressive developments observed in the last 20 years, the improvement of the installation methods of monolithic refractories is certainly to be taken into account. However, this evolution, from vibratable castables to shotcrete and drycrete was not applied to materials based on magnesia, which are still mostly commercialized as ramming mixes, or as pouring castables with poor properties due to excessive water use. The major issues associated to this lack of technology is the scarcity of submicrometric powders compatible to magnesian systems, and the expansion followed by hydration of the magnesia, which is a disruptive reaction. By a thorough research on the literature, some potential additives were identified to be tested as anti-hydration additives. Hydration tests of powders in autoclave, complemented by pH and rheological measurements on magnesia pastes have identified five possible additives which can be used to inhibit the hydration: tartaric acid, citric acid, boric acid, magnesium fluoride and microsilica. Salts from the organic acids can also be successfully used. Of these, microsilica also presented the advantage of providing the submicrometric particles necessary to improve the flow of the castable, and to improve the bond of the castable. The three acids are very effective in inhibiting the formation of magnesium hydroxide, but affect negatively flow properties and mechanical resistance after cure. Microsilica prevented hydration cracks due to the reaction between the silicic acid generated under basic environment with the newly formed brucite, leading to the precipitation of a magnesium-silica-hydrated phase of poor crystallinity between the magnesia grains. This phase does not promote volumetric change, and also enable water release at a wider temperature range. Due to its nature close to serpentine minerals, it forms forsterite and enstatite at low temperatures, thus generating suitable strength between room temperature and at least 1400 °C. Magnesium fluoride changed the nature of this magnesium-silica-hydrated phase, by being incorporated to it and forming a phase more similar to the humite minerals. These minerals present higher MgO:SiO2 molar ratio than serpentine, and their formation requires a lower content of microsilica for a same effect against hydration, which is beneficial for the overall properties of the castable. The properties of the castable, as well as the influence of a number of other variables (for instance, refractoriness under load, creep, cold crushing strength, cold modulus of rupture, bulk density and apparent porosity) were also studied and hereby reported. It is believed that this technology can be further developed for industrial use, provided that some issues regarding the properties at high temperatures are solved. Not only had the study and comprehension of the nature of the bond between microsilica and magnesia, and the role of magnesium fluoride been pioneered by this work, but also the methodology used to evaluate the hydration after the drying process of castings, which was close to real refractory components.

Submitted by Ronildo Prado (ronisp@ufscar.br) on 2017-08-23T12:31:55Z No. of bitstreams: 1 DissRGMS.pdf: 20398919 bytes, checksum: 000d866830c28ab133d11dda08ba6563 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-23T12:32:04Z (GMT) No. of bitstreams: 1 DissRGMS.pdf: 20398919 bytes, checksum: 000d866830c28ab133d11dda08ba6563 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-23T12:32:10Z (GMT) No. of bitstreams: 1 DissRGMS.pdf: 20398919 bytes, checksum: 000d866830c28ab133d11dda08ba6563 (MD5) / Made available in DSpace on 2017-08-23T12:32:16Z (GMT). No. of bitstreams: 1 DissRGMS.pdf: 20398919 bytes, checksum: 000d866830c28ab133d11dda08ba6563 (MD5) Previous issue date: 2015-12-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / The growing demand of the steel industry for cheaper and more efficient production processes creates a necessity for new refractory materials. These requirements are written in terms of more robust concretes, with a longer life cycle, and ease of installation and maintenance. New materials that fulfill these criteria are the Mgo-based refractory castable. However, during curing and drying stages these materials have a critical magnesia hydration reaction that can lead to damage and cracks. The resonance measurement of elastic modulus technique is one of the techniques used to study the effects of magnesia hydration on the castables. As an alternative to this technique is proposed a digital image correlation (DIC) method to monitor the cracks network evolution of refractory castables during the curing stage. Samples (CDPs) of freshly molded castables were subjected to a controlled environment to cure and to dry and images were captured of CDPs with a high resolution digital camera. The DIC is an optical full-field displacement measurement technique. This method is based on the registration of digital images recorded in the undeformed and deformed configurations to measure displacements. A Correli-Q4 based software were developed to detect the cracks and measures their surface crack density and its average crack opening in the sample. The study of some variables such as the paint technique used in the samples (required for application of the CID technique) and the positioning of samples within the thermal chamber were required to evaluate the robustness of the software. As a result of that effort it was possible to compare the CID technique with resonance measurement of elastic modulus. The conclusion is that both detect simultaneously the cracks network beginning. The results claim that the DIC technique is promising because it promotes possibility of measure and compare parameters relative to the crack network (surface crack density and average crack opening) for different compositions of castables, temperatures and relative humidity maintained during curing. The analysis of these cracks network paraviii meters was consistent with the theory in the literature demonstrating the potential of the proposed method. / A crescente busca da indústria siderúrgica por processos de produção mais eficientes cria uma demanda por novos materiais refratários. Isto significa, concretos mais robustos, com ciclo de vida maior e, de maior facilidade de instalação e manutenção. Entre os novos materiais que preenchem estes requisitos estão os concretos aluminosos contendo magnésia. Entretanto, o processamento destes materiais possui algumas etapas críticas devido à reação de hidratação da magnésia que pode causar trincas. Dentre as técnicas já utilizadas para quantificar esse processo, destaca-se o monitoramento do módulo elástico por meio da técnica de ressonância de barra. Este trabalho visa gerar uma nova alternativa de avaliação da fissuração de concretos refratários durante a etapa de cura do processamento desses materiais com o auxílio da técnica de correlação de imagens digitais (CID). Corpos de prova (CDPs) de concreto recém-moldados foram submetidos a um processo controlado de cura e secagem e, durante este, foram capturadas imagens de uma das faces dos CDPs com uma câmera digital de alta resolução. A partir das imagens, o programa Correli-Q4 é utilizado para calcular os campos de deslocamentos de uma região de interesse. Por meio destes campos, um método desenvolvido detecta as trincas formadas e mede o seu comprimento total e a sua abertura média. A partir do método desenvolvido foi possível comparar a técnica de CID com a de ressonância de barra e conclui-se que ambas detectam a formação da rede de fissuras sendo, portanto, complementares. A técnica de CID se mostrou promissora, visto que foi possível medir e comparar diversos parâmetros da rede de fissuras (densidade superficial e abertura média das trincas) para diversas composições de concretos, diferentes temperaturas e umidades relativas mantidas durante a cura. A análise desses parâmetros da rede de fissuras foi coerente com a literatura demonstrando o potencial do método.

In steel manufacturing, temperature control is a critical parameter,as it is extremely important for the steel quality. In general,disposable sensors are regularly immersed in the melt for temperaturemeasurements. There are commercially available sensors for continuoustemperature measurements. In this study, a refractory cement is used for encapsulation andcarrier of a resistive temperature detector, for continuoustemperature measurements in molten steel. This cement is normallyused for manufacturing of steel melt crucibles. The work in thisstudy is mostly experimental and consist of characterization of thecement and development of the sensor. The characterization includesthe mechanical properties, the thermal shock resistance, the steelmelt resistance and obtainable surface roughness, for differentpowder fractions, water-to-cement ratio, firings and mixing method.Process developments were also done for the manufacturing of thesensor element and its carrier system. The end goal for continuous temperature measurement in molten steelfor more than 60 minutes was not reached. However, functional sensorswere developed where temperatures up to 1000 °C were measured duringcalibrations, and the cement was well characterized. This work has been carried out within the Strategic innovationprogram "Smartare Elektroniksystem", a joint investment of Vinnova,Formas and Energimyndigheten.

Os concretos refratários são materiais que apresentam estrutura complexa contendo uma fração de partículas finas (D < 100?m) chamada de matriz e outra mais grosseira da ordem de até centímetros compostas por agregados. Dentre as propriedades importantes durante a aplicação dos concretos refratários, este trabalho aborda principalmente a energia de fratura e a resistência à erosão. Para a avaliação dessas propriedades vários estudos vêm sendo desenvolvidos nos últimos anos. A introdução do método da cunha para propagação estável da trinca é um exemplo, pois este método é utilizado para materiais com estrutura grosseira, como é o caso dos concretos. Já em se tratando de resistência a erosão, pouco se encontra na literatura a respeito desse assunto para concretos refratários. Tendo em vista a aplicação destes materiais, foi avaliado o comportamento da energia de fratura e resistência à erosão de concretos refratário aluminoso convencional antierosivo utilizado na indústria petroquímica com o objetivo de correlacionar os resultados de energia de fratura e a resistência à erosão. Para o desenvolvimento do trabalho foram usados dois concretos a com mesma composição química, variando somente o tamanho de agregado. Foram avaliadas além da energia de fratura e da resistência à erosão outras propriedades foram avaliadas como: os módulos elástico e de ruptura, porosidade aparente, fases cristalinas e microestrutura, e ainda foi realizado um estudo da matriz do concreto. Os resultados mostraram que a energia de fratura aumenta com o aumento do tamanho de agregado para o concreto estudado e a resistência a erosão aumenta com a temperatura de tratamento térmico devido a ceramização da matriz, conforme análise das imagens. Em função dos resultados, pode-se concluir que não foi observada uma boa correlação entre energia de fratura e resistência à erosão. Mas esta correlação de energia de fratura e de resistência à erosão pode ter o mesmo comportamento que a correlação entre comprimento característico e resistência á erosão para faixas específicas de tamanho de agregado. / Castables materials are known to be formed by a complex microstructure containing a fine fraction known as matrix (D<100?m) and another one known as aggregate containing thicker particles up to centimeters in size. Among its most notable properties regarding application, this research primarily addresses to the fracture energy and its erosion resistance. In recent years, some studies have been performed concerning such assessments. As an example, the wedge splitting procedure has been applied in the stable crack propagation method used for some thicker structured materials evaluation such the castables ones. On the other hand, a few data have been gathered concerning castable\'s erosion resistance. Facing such applications the main goal was the study of conventional aluminous anti erosive castables once it has been used in the petrochemical industry in order to correlate fracture energy and erosion resistance results. On this research, two castables samples with the same chemical composition were tested differing only its aggregate particle grain sizes. Besides fracture energy and erosion resistance, other important properties were evaluated as following: elastic modulus, rupture modulus, apparent porosity, crystalline phases and a castable matrix study was also carried out. The results demonstrate an increase on fracture energy as the studied castable aggregate size also increases and according to images studied, the erosion resistance suffers another increment regarding the thermal treatment temperature increase due matrix ceramization. Based on the obtained results, it can be concluded that no observation was made regarding the fracture energy and erosion resistance but it may exist an energy correlation between them once there is some observed between the characteristic length and the erosion resistance concerning the aggregate size range.