Calcium oxide

About: Calcium oxide is a research topic. Over the lifetime, 7600 publications have been published within this topic receiving 66104 citations. The topic is also known as: caustic lime & quicklime.

Characterization of Biochars Derived from Pyrolysis of Biomass and Calcium Oxide Mixtures

Abstract: This study forms the fundamental foundation for the development of a novel carbon arrestor process to produce a functionalized biochar. In this study, an experimental investigation was carried out on the production and characterization of biochar produced using a novel carbon arrestor process, which operates under the principle of in situ pyrolysis of biomass with lime (CaO) to produce a functionalized biochar product for use as an agronomic soil amendment. Two biomass sources were used, a woody biomass, Eucalyptus pilularis (or blackbutt) sawdust, and a herbaceous biomass, wheat stem. Characterization of the biochars produced as well as the gaseous products was completed via thermogravimetric analysis, micro gas chromatography, solid-state Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption, and scanning electron microscopy. The addition of CaO to the pyrolysis process resulted in a significant reduction in CO2 evolution via the carbonation reaction of CaO and the formation of H2 and CH4 ...

Lime addition and curing effects on the index and compaction characteristics of a montmorillonitic soil

Abstract: The effects of amount of lime added and of the curing period on the liquid limit, shrinkage limit and compaction characteristics of a montmorillonitic soil are investigated. Incremental additions of lime result in a progressive decrease in liquid limit, increase in shrinkage limit, decrease in maximum dry density and increase in optimum moisture content of the soil on immediate testing. Curing the soil with lime also has a distinctive influence on its properties. On extended equilibration for a given lime addition, liquid and shrinkage limits increase with time, while the maximum dry density and optimum moisture content values show a decrease. The physico-chemical mechanisms which alter the montomorillonitic soil properties on addition of lime and subsequent curing are highlighted.(A)

Calcium silicates: A new class of highly regenerative sorbents for hot gas desulfurization

Abstract: A thermodynamic and kinetic study on the use of calcium silicates and silica-supported lime as regenerative sorbents for desulfurization of hot combustion gases showed that, except for ..gamma..-Ca/sub 2/SiO/sub 4/ and Ca/sub 3/SiO/sub 5/, all the calcium silicates and the silica-supported calcium oxide were as reactive as, or more reactive than, calcium oxide. The regeneration rates of these sorbents were substantially higher than that of calcium oxide, the rate of thermal decomposition of the sulfated mono- and dicalcium silicates being about 15 times higher than that of calcium sulfate. Sulfation rates of CaSiO/sub 3/ and Ca/sub 2/SiO/sub 4/ were first order with respect to sulfur dioxide only for partial pressure of sulfur dioxide Vertical Bar3; 3000 ppm. The silica-supported calcium oxide after heat treatment at 1075/sup 0/C had ..beta..-CaSiO/sub 3/ on its surface.

The role of lime migration in lime pile stabilization of slopes

Abstract: Lime piles, which essentially consist of holes in the ground filled with lime, have been successfully used worldwide for the in situ treatment of failing clay slopes. The literature on the technique does not, however, permit a full explanation as to why lime piles work or how to design them. It is widely reported that migration of the lime from the piles into the surrounding clay provides the major stabilizing mechanism. This paper aims to review the literature on lime migration from piles and to report the results of recent research at Loughborough University to determine migration mechanisms from compacted quicklime piles. Potential applications are then discussed in the light of the findings. Hydroxyl (OH - ) ion migration by diffusion processes in intact clay is shown to be limited by high reactivity to approximately 20-30 mm. Nevertheless hydraulic transport via dehydration cracking or other discontinuities in the clay mass could result in migration extending for far greater distances. Calcium (Ca 2+ ) ion migration, would be expected to occur over distances greater than 1 m in ten years. Thus while full clay stabilization might only occur to a limited degree, modification of the clay is likely to be widespread. Mineralogical changes indicate a strength gain equivalent to that of lime mixed with clay at the initial lime consumption (Eades & Grim 1966) value plus 2% and cured for 28 days.

Calcium silicate granules forming a microporous structure

Abstract: The invention deals with calcium silicate granulates or powders with a microporous structure, which are obtained, by reacting crystalline or, if required, amorphous silicon dioxide, or materials containing the same, with calcium oxide or materials containing the same, in a CaO to SiO2 molar ratio of 0.8:1 to 1:1:1, by homogenizing the same in water together with a suitable additive and molding, autoclave setting, comminuting, drying, and grading with the further proviso that the homogenization during the reaction is carried through by dispersion of the starting materials in water by adding an anion-active surfactant, which had previously been converted in water into a microporous stable foam, obtained as absorbents and adsorbents for liquids, vapors and gases, as well as calcium silicate granulates of this type with further developing additives, which in the use for absorption of hydrophilic liquids are fatty amines, whereas in the use of the absorbent for oleophilic liquids and gases polyamide waxes, fatty amine salts or saponification resistant alkoxy silanes may be used.