Topic
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.
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TL;DR: The structural changes of NaOH- and LiOH-impregnated Ca(OH)2 during calcination were studied by applying differential thermal analysis, IR and X-ray diffraction techniques as discussed by the authors.
Abstract: Promotion of CaO by Na+ or Li+ leads to an active and selective catalyst for the oxidative coupling of methane into higher hydrocarbons. The structural changes of NaOH- and LiOH-impregnated Ca(OH)2 during calcination were studied by applying differential thermal analysis, IR and X-ray diffraction techniques. The results indicate that both NaOH and LiOH interact with Ca(OH)2 during drying and calcination. The alkali hydroxides tend to dehydrate along with Ca(OH)2 into oxides. In situ infrared spectroscopic studies suggest that dehydration of the mixed hydroxides occurs around 450°C. The measured lattice parameter values indicate that the inclusion of Na+ or Li+ ions into the CaO matrix remains very limited. It may be assumed that most of the alkali oxide remains in well dispersed state over the CaO matrix when calcining the samples at 600°C. On increasing the alkali content above 10% no further increase in hydrocarbon selectivity is achieved.
25 citations
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TL;DR: In this paper, the effects of water leaching on the engineering and physical properties of a lime-treated expansive clay in north-central Texas were determined. And the results indicated that leaching does have a detrimental impact on the physical properties.
Abstract: The effects that continuous water leaching has on the engineering and physical properties of a lime-treated expansive clay in north-central Texas were determined. Seventy laboratory-prepared lime-treated clay samples were subjected to continuous accelerated leaching for periods of 45 and 90 days in large-diameter, flexible-wall leach cylinders. The soils' physical properties were measured before and after leaching, then graphically and statistically analyzed for significant changes. Results indicated that leaching does have detrimental impact on the physical properties of lime-treated expansive clays. The property changes are related to lime content and initial moisture content. Permeability of all samples increased dramatically with the addition of lime. Maximum detrimental changes generally occurred at lime contents at or less than the lime modification optimum. At lime contents at or above the lime stabilization optimum, the detrimental effects of leaching were minimized or eliminated. Changes to properties upon leaching varied depending on their compaction water content relative to the optimum.
25 citations
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27 Jul 2011
TL;DR: In this paper, a recycled aggregate is made by pre-add water to carbonated curing wastes for forming balls which absorb carbon dioxide gas in industrial waste gas, which belongs to the building material technique field.
Abstract: The invention relates to a recycled aggregate made by pre-adding water to carbonated curing wastes for forming balls which absorb carbon dioxide gas in industrial waste gas, which belongs to the building material technique field. The recycled aggregate is made by adopting the following processes of: utilizing steel slag or cement containing carbonization compositions as a raw material, adding water for even mixture, and implementing the granulation for spheroidizing so as to make the recycled aggregate under the curing of carbonization gas; and the carbonization compositions include one or more than one of calcium oxide, calcium hydroxide, dicalcium silicate, tricalcium silicate, hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium ferrite, ettringite, magnesium hydroxide and magnesium oxide, and the carbonization compositions have a weight percentage of no less than 30 percent in materials. The recycled aggregate has the main point that: the accelerated carbonization technique is utilized to treat industrial wastes such as steel slag, sludge and waste concrete, solidify and store carbon dioxide of greenhouse gas, and make the recycled aggregate. The pollution problem of wastes such as steel slag and waste gas is released; meanwhile, the light recycled aggregate with excellent performance is prepared.
25 citations
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04 Nov 2009
TL;DR: In this article, a method for the preparation of nanometer calcium carbonate for water-soluble ink by a wet method is described, which is characterized in that the calcium oxide undergoes slaking in the gyratory slaker and first aging, is added with a crystal control agent, undergoes second aging after undergoing first bubbling carbonation and was added with material looseness modifier and a surface treatment agent to carry out second modification.
Abstract: The invention relates to a method for preparing nanometer calcium carbonate, in particular to a method for preparing nanometer calcium carbonate special for water soluble ink by a wet method. The method comprises the following steps: calcining and smashing limestone to prepare calcium oxide, classifying the calcium oxide, choosing fine quality calcium oxide to be slaked in a gyratory slaker, be aged twice and carbonized twice to prepare calcium carbonate. The method is characterized in that the calcium oxide undergoes slaking in the gyratory slaker and first aging, is added with a crystal control agent, undergoes second aging after undergoing first bubbling carbonation and is added with a material looseness modifier and a surface treatment agent to carry out second modification. The method farthest utilizes the low-grade limestone to prepare the nanometer calcium carbonate product special for water-based ink, with mean grain size of 10-40nm and specific surface of 40-70m/g and enhances the transparency and cohesive force of the ink.
25 citations
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TL;DR: In this article, the effect of adding 1, 2 and 3 per cent of sodium chloride during lime treatment was investigated and the results showed that the increase in unconfined compressive strength was between 100 and 300 percent over that of the untreated or lime-only treated soils for clay contents between 30 and 50 percent of the total soil composition.
Abstract: Kaolinitic and montmorrillonitic soils were prepared from commercial quality sand and clay in 10, 30 and 50 per cent clay contents. Lime was added in 2, 4 and 8 per cent by dry weight of soil. The effect on optimum moisture content, maximum dry density and unconfined compressive strength of adding 1, 2 and 3 per cent of sodium chloride during lime treatment was investigated. At 28 days strength gains due to sodium chloride were generally higher in lime-kaolinite than in lime-montmorillonite soils. These amounted to between 100 and 300 per cent increase in unconfined compressive strength over that of the untreated or lime-only treated soils for clay contents between 30 and 50 per cent of the total soil composition. For most soils the optimum salt content for a maximum strength gain appears to be approximately one per cent. (Author/TRRL)
25 citations