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Chemistry and Technology of Lime and Limestone
01 Dec 1966-
TL;DR: The ICCROM as discussed by the authors describes the formation and properties of limestone; exploration and extraction; processing and uses; and theory of calcination of lime; and methods of slaking of lime.
Abstract: Formation and properties of limestone; exploration and extraction. Processing and uses. Theory of calcination. Definitions and properties of lime. Manufacture. Theory of lime hydration. Methods of slaking. Analytical testing. -- ICCROM
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TL;DR: The reversible reaction between CaO and CO2 is an extremely promising method of removing CO2 from the exhaust of a power station, generating a pure stream of CO2 ready for geological sequestration.
880 citations
TL;DR: In this paper, the catalytic behavior of olivine, a common, naturally occurring mineral containing magnesium, iron oxides and silica, was investigated in a laboratory scale, biomass gasification unit.
Abstract: Naturally occurring catalytic substances are employed in biomass steam-gasification processes to enhance the yield of fuel gas and reduce its tar content by cracking and reforming the high molecular weight organic components. Calcined dolomite is widely used for this purpose; it exhibits good catalytic activity under the operating conditions of the gasifier. However, due to its poor mechanical strength, it gives rise to a large production of fines in a fluidised-bed environment. This work reports an investigation into the catalytic behaviour of olivine, a common, naturally occurring mineral containing magnesium, iron oxides and silica: iron is known to play a positive role in tar decomposition reactions. The gasification runs, performed with a laboratory scale, biomass gasification unit, show that the olivine activity is close to that exhibited by dolomite under comparable operating conditions. Olivine has the additional advantage, however, that its resistance to attrition in the fluidised bed is much greater, similar to that of sand. Parametric sensitivity studies of a gasification process, utilising olivine as the fluidised-bed inventory, indicate an optimum gasification temperature of just above 800°C, and little influence of the steam/biomass ratio in the range 0.5–1.
657 citations
TL;DR: In this article, a detailed analysis of clay-rich materials following firing is presented, showing that initial mineralogical differences between two raw materials (one with carbonates and the other without) influence the texture and mineralogical evolution of the ceramics as T increases from 700 to 1100°C.
Abstract: Mineralogical, textural and chemical analyses of clay-rich materials following firing, evidence that initial mineralogical differences between two raw materials (one with carbonates and the other without) influence the tex- tural and mineralogical evolution of the ceramics as T increases from 700 to 1100° C. Mineralogical and textural changes are interpreted considering local marked disequilibria in a system that resembles a small-scale high- T meta- morphic process ( e.g., contact aureoles in pyrometamorphism). In such conditions, rapid heating induces significant overstepping in mineral reaction, preventing stable phase formation and favoring metastable ones. High- T transfor- mations in non-carbonate materials include microcline structure collapse and/or partial transformation into sanidine; and mullite plus sanidine formation at the expenses of muscovite and/or illite at T ‡ 800° C. Mullite forms by mus- covite-out topotactic replacement, following the orientation of mica crystals: i.e., former (001) muscovite are ^ to (001)mullite. This reaction is favored by minimization of free energy during phase transition. Partial melting followed by fingered structure development at the carbonate-silicate reaction interface enhanced high- T Ca (and Mg) silicates formation in carbonate-rich materials. Gehlenite, wollastonite, diopside, and anorthite form at carbonate-silicate interfaces by combined mass transport (viscous flow) and reaction-diffusion processes. These results may add to a better understanding of the complex high- T transformations of silicate phases in both natural ( e.g., pyrometamor- phism) and artificial ( e.g., ceramic processing) systems. This information is important to elucidate technological achievements and raw material sources of ancient civilizations and, it can also be used to select appropriate clay com- position and firing temperatures for new bricks used in cultural heritage conservation interventions.
495 citations
Cites background or methods from "Chemistry and Technology of Lime an..."
...Upon storage at 22°C and 55 % RH, burnt lime (CaO) readily transforms into portlandite according to the following reaction (Boynton, 1980): portlandite CaO + H2O ® Ca(OH)2 (4)....
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...G. Cultrone, C. Rodriguez-Navarro, E. Sebastian, O. Cazalla, M.J. De la Torre starts to decompose according to (1) at ~ 700°C (1 atm pressure), while calcite decomposes at higher T (830 – 870°C) according to (3) (Boynton, 1980)....
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...atm pressure), while calcite decomposes at higher T (830 – 870°C) according to (3) (Boynton, 1980)....
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TL;DR: In particular, the mechanisms of the sulfation reaction are still not properly understood, and there is dispute over the explanation of the well-known temperature maximum for optimum sulfur capture found in FBC boilers as mentioned in this paper.
414 citations
TL;DR: In this paper, the changes in brick porosity upon firing and its relation to the mineralogical composition are examined, showing that the presence or absence of carbonates strongly influences the porosity development and, therefore, the brick texture and physical-mechanical properties.
Abstract: The changes in brick porosity upon firing (700 up to 1100 � C) and its relation to the mineralogical composition are examined. Two types of raw clay with a composition representative of that used in brick-making industry were selected to manufacture the bricks: one contains notable amounts of carbonates, with a grain size of under 1 mm, and the other is predominantly quartzitic and lacking in carbonates. We demonstrate that the presence or absence of carbonates strongly influences the porosity development and, therefore, the brick texture and physical-mechanical properties. The carbonates in the raw clay promote the formation of fissures and of pores under 1 mm in size when the bricks are fired between 800 and 1000 � C. The absence of carbonates results in a continuous reduction in porosity and a significant increase in the pore fraction with a radius (r) > 1 mm as the firing temperature rises and smaller pores coalesce. Porosity and pore size distribution results obtained from the combined use of hydric tests (HT), mercury intrusion porosimetry (MIP) and digital image analysis (DIA) of scanning electron microscopy photomicrographs are compared. A clear correlation between the water absorption and drying behaviour of the bricks and the porosity plus pore size distribution is observed. DIA discloses the evolution of size, shape and connectivity of macropores (r > 1 mm) and evidences that MIP results underestimate the macropore content. Conversely, MIP gives a good estimate of the open porosity and of the distribution of pores with r <1 mm. It is concluded that the combined use of these complementary techniques helps to fully characterise the pore system of bricks. These results as well as the study of the evolution of the speed of ultrasound waves vs. time yield useful information to evaluate the bricks physical–mechanical behaviour and durability. The relevance of these findings in the conservation of historic buildings is discussed. # 2003 Elsevier Ltd. All rights reserved.
370 citations