Sintering of lime doped with La2O3 and CeO2

Ghoneim, N.M.; Mandour, M. A.; Serry, M. A.

doi:10.1016/0272-8842(89)90049-7

Cited by 22 publications

(11 citation statements)

References 6 publications

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“…The excess amount will coexist with the lime phase in free state. Therefore, the marginal increase in density of CeO 2 added sintered lime than La 2 O 3 added sintered lime is due to the higher true density of CeO 2 (7⋅12 g/cc) than La 2 O 3 (6⋅95 g/cc), which was mostly present in undissolved state in grain boundary (Ghoneim et al 1989).…”

Section: Resultsmentioning

confidence: 97%

“…The slag resistance as well as hydration resistance of lime can be improved by liquid state or solid state sintering with the aid of small amounts of additives (Hubble 1969;Nadachowski 1976;Shi et al 1984). The addition of Fe 2 O 3 , Al 2 O 3 and CuO has enhanced sintering of lime through liquid phase sintering and lanthanides like La 2 O 3 and CeO 2 through solid state sintering of lime (Ghoneim et al 1989;Ghosh et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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Solid state sintering of lime in presence of La2O3 and CeO2

et al. 2003

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The sintering of lime by double calcination process from natural limestone has been conducted with La 2 O 3 and CeO 2 additive up to 4 wt.% in the temperature range 1500-1650°C. The results show that the additives enhanced the densification and hydration resistance of sintered lime. Densification is achieved up to 98⋅ ⋅5% of the theoretical value with La 2 O 3 and CeO 2 addition in lime. Grain growth is substantial when additives are incorporated in lime. The grain size of sintered CaO (1600°C) with 4 wt.% La 2 O 3 addition is 82 µ µm and that for CeO 2 addition is 50 µ µm. The grains of sintered CaO in presence of additive are angular with pores distributed throughout the matrix. EDX analysis shows that the solid solubility of La 2 O 3 and CeO 2 in CaO grain is 2⋅ ⋅9 and 1⋅ ⋅7 weight %, respectively. The cell dimension of CaO lattice is 4⋅ ⋅803 Å. This value decreases with incorporation of La 2 O 3 and CeO 2. The better hydration resistance of La 2 O 3 added sintered lime compared to that of CeO 2 added one, is related to the bigger grain size of the lime in former case.

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Solid state sintering of lime in presence of La2O3 and CeO2

et al. 2003

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“…59 Densification of pure CaCO 3 -derived lime was appreciably enhanced by doping with 2?8 wt-%La 2 O 3 and firing 2 h at 1600uC, mainly through SSS. 58 However, when sintering limestone-derived lime, 59 the liquid (via LPS) interferes with the role of La 2 O 3 in the SSS of lime. Accordingly, limestone-derived lime samples after 2 h at 1600uC show lower bulk density values than reagent grade derived lime samples doped with the same amounts of La 2 O 3 .…”

Section: Rare Earth Oxidesmentioning

confidence: 99%

Improving the hydration resistance of lime-based refractory materials

Li¹,

Zhang²,

Lee³

2008

International Materials Reviews

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Studies to improve the hydration resistance of lime-based materials are reviewed. The methods described include densification of the lime aggregate by addition of sintering aids and surface treatment. Methods for assessing hydration resistance are also reviewed. Additions of ZrO 2 , TiO 2 (including Ti chelating compounds) and rare earth oxides can improve the hydration resistance of CaO aggregate by, it is believed, enhancing solid state sintering without sacrificing refractoriness via formation of hydration resistant solid solutions. Fe 2 O 3 , Al 2 O 3 (as well as Al chelating compounds and Al metal), CuO and V 2 O 5 , act as liquid forming aids. These additives improve the sintering of lime and subsequently the hydration-resistance via formation of liquids at high temperature which cool to produce hydration-resistant solids surrounding the lime polycrystals. However, the liquids formed may significantly reduce the refractoriness of lime materials, thus eroding their particular advantage. The same problem is thought to arise on addition of salts such as CaCl 2 and NaF. The hydration resistance of CaO aggregates can also be improved by surface carbonation and surface treatment using acids, phosphates, machine oils, silicones and fluxes. Surface carbonation of CaO aggregate is proving to be a promising experimental method, but practical problems currently limit its application on an industrial scale. A combination of the two methods mentioned above should therefore be even more effective in improving the hydration resistance of CaO refractory materials.

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“…Lime-based refractories are often used in secondary steelmaking processes due to its relatively low vapor pressure at high temperatures and numerous high-temperature superior properties [1][2][3]. Furthermore, with the development of clean steel production, lime-based refractories have been becoming more and more important [4,5]. CaOis one of the most suitable refractory constituents which can meet with requirements on durability and purifying function.…”

Section: Introductionmentioning

confidence: 99%

Effect of Al(OH)3 and La2O3 on the sintering behavior of CaO granules via CaCo3 decomposition

Wei

et al. 2020

Sci Sintering

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Hydration resistance of CaO aggregates is the key to the successful application of lime-based refractories. Granulation technology on limestone with additives and one step calcination method was used in this study to investigate the effects of Al(OH)3 and La2O3 on the sintering behavior and the hydration resistance of CaO granules. The result showed that the hydration resistance of CaO granules was improved significantly by adding Al(OH)3 and La2O3. The shell of sintered CaO granules was relatively dense after calcination and the specific surface area of CaO granules decreased from 7.5?10-2 m2/g to 1.2?10-2 m2/g. The average pore size of CaO granular was decreased from 3.54 ?m to 0.83 ?m due to the liquid phase sintering when Al(OH)3 additive was used. La2O3 promoted the densification of CaO compact by the ion substitution and solution with CaO. La3+ approached into CaO lattices, which enlarged the vacancy concentration of Ca2+ and accelerated the diffusion of Ca2+.

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Sintering of lime doped with La2O3 and CeO2

Cited by 22 publications

References 6 publications

Solid state sintering of lime in presence of La2O3 and CeO2

Solid state sintering of lime in presence of La2O3 and CeO2

Improving the hydration resistance of lime-based refractory materials

Effect of Al(OH)3 and La2O3 on the sintering behavior of CaO granules via CaCo3 decomposition

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