Physico-chemistry of silica / Na silicate interactions during consolidation. Part 2: Effect of pH

Tognonvi, Monique Tohoué; Soro, Julien; Gelet, Jean‐Louis; Rossignol, Sylvie

doi:10.1016/j.jnoncrysol.2011.11.005

Cited by 20 publications

(6 citation statements)

References 22 publications

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“…[9] The largest mechanical strengths observed in agglomerates immersed in water and cured at temperatures exceeding 250 8C are attributed to the removal of the hydroxyl groups, according to the mechanism shown by Owusu. [9] Moreover, these results are consistent with the studies of Tognonvi et al, [16] who found that heat treatments at lower temperatures tend to form films with greater solubility in water, due to the tendency of these films (with increased presence of ionic bonds due to sodium ions) to reconstitute spheres of hydration eliminated during the heat processing.…”

Section: Resultssupporting

confidence: 89%

Influence of drying temperature and atmosphere on the mechanical strength of iron‐ore agglomerates and sodium silicates for application in sintering processes

et al. 2015

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This paper presents the influence of drying temperature and atmosphere on the mechanical strength of iron-ore agglomerates and sodium silicates. Mixtures of different pellet feed and sodium silicates were produced with a ball disc and cured at various temperatures. The resulting products exhibited sufficiently high mechanical strength to be transported over long distances and handled until their use in sintering processes. The agglomerates were dried/cured at temperatures between 100-550 8C and in gaseous atmospheres consisting of air and/or carbon dioxide. During this process, a strong influence of both temperature and atmosphere on the compression strength after contact with water, as well as on the morphology of the sodium silicates, was observed. The use of carbon dioxide atmosphere during drying proved effective for achieving high mechanical strength after water immersion. A phenomenological approach was developed to explain the results in order to connect morphology and mechanical properties.

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Section: Resultssupporting

confidence: 89%

Influence of drying temperature and atmosphere on the mechanical strength of iron‐ore agglomerates and sodium silicates for application in sintering processes

et al. 2015

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“…In contrast, the sand is not easily weathered due to its stability as well as its various size distributions (i.e., specific surface area) and does not provide siliceous species even after 24 hours under stirring [7]. However, consolidated materials were obtained by impregnating silica sand with the solution [8]. To increase the surface reactivity, the sand was also functionalized by a prior basic attack.…”

Section: Introductionmentioning

confidence: 99%

Role of the silica source on the geopolymerization rate

Autef

Joussein

Gasgnier

et al. 2012

Journal of Non-Crystalline Solids

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“…A maior resistência do aglomerado após exposição à água, quando o mesmo é exposto a temperaturas superiores a 250°C é atribuída à remoção dos grupos hidroxila (OH), conforme mecanismo apresentado por Owusu [2]. Além disso, esses resultados estão de acordo com os estudos de Tognonvi et al [9], que constataram que tratamentos térmicos a temperaturas mais baixas tendem a formar um filme com maior solubilidade em água, devido à tendência destes filmes (com maior presença de ligações iônicas devido ao sódio) reconstituírem sua esfera de hidratação destruída durante o processamento térmico. Observou-se que a exposição do aglomerado em temperaturas de 150°C a 550°C em atmosfera com ar atmosférico não promove alterações volumétricas significativas.…”

Section: Resultados E Discussâounclassified

Influência Da Temperatura E Atmosfera De Secagem Sobre a Resistência Mecânica De Um Aglomerado De Minério De Ferro Para Uso Em Sinterização

Dutra¹,

Dias²,

Costa³

et al. 2014

ABM Proceedings

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ResumoEste artigo apresenta a influência da temperatura e da atmosfera de secagem sobre a resistência mecânica de um aglomerado esférico, com diâmetro entre 3 mm e 8 mm, constituído de pellet feed e silicato de sódio, produzido através de pelotamento em discos e endurecido em temperaturas até 550ºC. O aglomerado obtido a partir deste processo apresenta características que permitem que o mesmo possa ser transportado a longas distâncias e manuseado até a sua utilização na sinterização. As principais técnicas experimentais utilizadas neste estudo foram difração de raios-X, espectroscopia Raman, microscopia eletrônica de varredura e análise térmica. O aglomerado foi submetido à secagem em temperaturas entre 100°C e 550ºC e atmosferas constituídas de ar atmosférico e/ou CO2. Durante o processo de secagem, observou-se a influência da temperatura e da atmosfera sobre a resistência à compressão do aglomerado após exposição à água, assim como na morfologia do silicato de sódio, evidenciando uma dependência entre elas. O uso de CO2 durante a secagem mostrou-se eficiente para a formação de um aglomerado com maior resistência mecânica após exposição à água. Palavras-chave: Aglomerado de minério de ferro; Resistência mecânica; Silicato de sódio líquido. Abstract This paper presents the influence of the drying temperature and atmosphere on the mechanical strength of agglomerate composed by pellet feed and sodium silicate, produced by balling and cured at temperatures up to 550ºC. The product obtained from this process has high mechanical strength that allows it to be transported over long distances and handled until its use in sintering .The main experimental techniques used in this study were X-ray diffraction, Raman spectroscopy, scanning electron microscopy and thermal analysis. The agglomerate was submitted to drying/cure at temperatures varying between 100 and 550°C and gaseous atmosphere consisting of air and /or carbon dioxide (CO2). During the drying/cure processes, it was observed a strong influence of both temperature and atmosphere on the compression strength after exposure to water, as well as on the morphology of the sodium silicate, demonstrating a dependency between them. The use of CO2 during drying proved to be effective to achieve an increase of compression strength after exposure to water.

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Physico-chemistry of silica / Na silicate interactions during consolidation. Part 2: Effect of pH

Cited by 20 publications

References 22 publications

Influence of drying temperature and atmosphere on the mechanical strength of iron‐ore agglomerates and sodium silicates for application in sintering processes

Influence of drying temperature and atmosphere on the mechanical strength of iron‐ore agglomerates and sodium silicates for application in sintering processes

Role of the silica source on the geopolymerization rate

Influência Da Temperatura E Atmosfera De Secagem Sobre a Resistência Mecânica De Um Aglomerado De Minério De Ferro Para Uso Em Sinterização

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