Thermal characterization of a Spanish red mud

Pascual, J.; Corpas, Francisco J.; López-Beceiro, Jorge; Benítez‐Guerrero, Mónica; Artiaga, Ramón

doi:10.1007/s10973-008-9230-9

Cited by 64 publications

(44 citation statements)

References 22 publications

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“…Em seguida, observam-se cinco efeitos endotérmicos: a) A 275 ºC em conseqüência da decomposição da gibbsita com a formação de uma alumina de transição (χ-Al 2 O 3 ) ou criptocristalina [42]. Considerando os resultados obtidos por [46], sugere-se que o caminho de reação até a completa formação de coríndon (α-Al 2 O 3 ) seja o seguinte: Gibbsita χ-Al 2 O 3 κ-Al 2 O 3 α-Al 2 O 3 ; b) Dois picos endotérmicos de pouca intensidade entre 305 e 345 ºC, que estão associados à decomposição de goethita para a formação de hematita [47]; c) A 680 ºC, que está associado à decomposição da calcita [48][49]; d) A 1198 ºC, o qual pode estar associado à decomposição da soldalita [49] ou à fusão de silicatos presentes no material [50].…”

Section: Comportamento Térmicounclassified

“…6, constata-se que a evolução das fases cristalinas presentes na LV em função da temperatura de queima podem ser resumidas das seguintes maneiras: a) A 750 ºC, as fases cristalinas presentes na amostra são: anatásio, sodalita e hematita. b) A 850 o C, as únicas fases minerais detectadas são hematita, sodalita e uma fase transitória não indexada, provavelmente do tipo Ca-Si-Al ou Na-Si-Al, precursora de nefelina localizada em 2Θ = 21,5 º (2,05 Å) [49]. c) Em 950 o C, as fase dominantes no difratograma são: hematita, sodalita, nefelina e quartzo que desaparece aos 1050 o C; d) Entre 1050-1150 ºC, as únicas fases que se observam no difratograma são: hematita, nefelina e sodalita.…”

Section: Evolução Das Fases Com a Temperaturaunclassified

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Estudo do comportamento térmico e propriedades físico-mecânicas da lama vermelha

et al. 2010

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RESUMONeste trabalho, estudou-se o comportamento térmico, a evolução das fases cristalinas com a temperatura e as propriedades físico-mecânicas da Lama Vermelha (LV) procedente da indústria de alumínio do Estado do Maranhão. O estudo foi realizado por Análise Termogravimétrica (TG) e Calorimetria Exploratória Diferencial (DSC), Dilatometria Ótica até 1350 ºC; enquanto a evolução das fases cristalinas com a temperatura foi realizada no intervalo entre 750 a 1150 ºC por Difração de Raios-X (DRX). As propriedades físico-mecânicas como Superfície Específica, Granulometria, Limite Plástico (LP), Limite de Liquidez (LL), Índice de Plasticidade (IP), Tensão de Ruptura a Flexão (TRF), Absorção de Água (AA), Retração Linear Após Queima (R L ) e Porosidade Aparente (PA) foram determinadas nas mesmas temperaturas. As seguintes fases cristalinas foram detectadas: hematita, sodalita e anatásio entre 750-850 ºC; e hematita, nefelina e sodalita entre 950-1150 o C. Os ensaios tecnológicos demonstraram que a LV pode ser aplicada para o processamento de materiais cerâmicos estruturais, pois apresenta pouca reatividade entre 870-950 ºC, com elevada AA, e baixas R L e TRF. Entre 950 e 1350 ºC, a LV sofreu uma retração que variou entre 5-50 %, com fusão total a 1350 ºC, devido à presença de fases minerais do tipo feldespatoides em sua composição. Palavras-chave:Resíduo de bauxita, materiais cerâmicos, caracterização, lama vermelha. Thermal behavior and physical-mechanical properties of red mud ABSTRACTThe present work studied the thermal behavior, the evolution of the crystalline phases with temperature and the ceramic properties of the red mud (bauxite tailing) from an aluminium industry of the Maranhao state. The research was carried out by Simultaneous Thermal Analysis (TG-DTA), Optical Dilatometry up to 1350 ºC, while the evolution of the crystalline phases was performed by X-ray diffraction analysis upon heating between 750 to 1150 ºC. Physical-mechanical properties, like Specific Surface Area, Particle Size Distribution, Plastic Limit (PL), Liquid Limit (LL), Plasticity Index (PI), Flexural Strength, Water Absorption (WA), Linear Shrinkage After Firing (LS) and the Apparent Porosity (AP) were also determined at the same range of temperature. The following major crystalline phases were detected: hematite, sodalite, and anatase at 750 ≤ T ≤ 850 o C; and hematite, nepheline and sodalite at 950 ≤ T ≤ 1150 o C. The technological experiments indicated that red mud can be used for the processing of structural ceramic materials, since it is an inert material between 870-950 ºC and presents highest water absorption and lowest shrinkage and flexural strength. At 950 ≤ T ≤ 1350 ºC, red mud presented a high shrinking of almost 5 to 50 % with total fusion at 1350 ºC, due to the presence of feldspathoids phases in its mineral composition.

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Section: Comportamento Térmicounclassified

Section: Evolução Das Fases Com a Temperaturaunclassified

Estudo do comportamento térmico e propriedades físico-mecânicas da lama vermelha

et al. 2010

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“…Although the overall course of the processes is widely known, the effects of various crystal-chemical and chemical factors on the transformation mechanisms and properties of the products are still under vigorous debate [1,3]. This type of research focuses usually on monomineral synthetic samples [e.g., [4][5][6][7][8][9][10] and does not fully reflect the complexity of the processes during thermal transformations of natural Fe-oxide-rich materials [e.g., [10][11][12][13][14][15][16][17], archeological findings [18,19] and composite industrial products or wastes [20][21][22]. A good example of such a complex system are bog iron ores.…”

Section: Introductionmentioning

confidence: 99%

Mineral transformations and textural evolution during roasting of bog iron ores

Rzepa

Bajda

Gaweł

et al. 2015

J Therm Anal Calorim

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The processes occurring during roasting of bog iron ores were characterized using TG-DTG-DTA-QMS, XRD, FTIR and specific surface analysis. Removal of physically adsorbed water is followed by dehydroxylation of iron oxyhydroxides and oxidation of organic matter at 200-600°C. The main product of the transformations is disordered nanocrystalline (proto)hematite or hematite/-maghemite mixture, depending on organic matter content and heating conditions. The conversion of iron oxyhydroxides to hematite occurs at temperatures different than those reported for pure compounds. At higher temperatures, protohematite undergoes recrystallization to the stoichiometric hematite, and manganese oxides are partially reduced. At 1000°C, the roasting products consist of hematite and cristobalite together with Mn-Fe spinels if the initial ore contained Mn oxides. The admixtures of various secondary silicates were encountered as well. Low-to moderate-temperature roasting slightly affects the specific surface area and lowers volume of micropores. The hightemperature transformations lead to decrease in the specific surface area and to the destruction of porous texture of the bog iron ores. Although the general course of the processes during roasting was similar in all the samples, some of their details as well as mineralogy and properties of the products are highly dependent on the composition of the initial material.

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“…The production of one ton of alumina generates approximately 0.3-2.5 tons of red mud, depending on the grade of bauxite (Pascual et al, 2009). At the Pingguo alumina refinery in China, one ton of alumina usually yields one ton of red mud.…”

Section: Introductionmentioning

confidence: 99%

“…Their results indicated that different levels of pressure can assist in the separation of mineral phase signals in thermoanalytical curves. Alp and Goral (2003), Atasoy (2005Atasoy ( , 2007, Pascual et al (2009) and Palmer and Frost (2010) used thermogravimetry (TG) and differential thermal analysis (DTA) to study the thermal behavior of red mud samples between room temperature and 1400°C. These experiments showed that different red muds had similar thermal behavior at temperatures below 700°C, but their mineral phases decomposed and reacted differently at higher temperatures.…”

Section: Introductionmentioning

confidence: 99%