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.

Permeability and leachate characteristics of stabilized class f fly ash

Abstract: A 2-year laboratory investigation of the permeability and leachate characteristics of stabilized fly ash has been completed at West Virginia University. Two class F fly ashes rom coal-fired power plants in West Virginia were amended with either lime, cement, or bentonite. Stabilized specimens were permeated in either rigid- or flexible-wall permeameters. Permeant liquids included distilled water, highly concentrated organic solutions, and acidic solutions. Effluents from the permeability tests were collected periodically during the tests and analyzed for toxic elements. Results from the study indicate, for the ashes tested, permeabilities near 1.0E-06 cm/sec can readily be obtained when 15% (by weight) of lime or cement is added to the fly ash. Much lower permeabilities (1.0E-08 cm/sec) can be obtained by substituting bentonite in place of the lime or cement. Addition of lime or cement appears to stabilize the fly ash with respect to toxic elements being leached from the ash. Bentonite may not be as successful at fixing the elements onto the fly ash. In conclusion, difficulty in using fly ash as a liner material probably does not lie in the ability to obtain low permeability nor in fixing the toxic elements from leaching but rather in combining those two properties into one material. Permeability can be decreased to acceptable values through the addition of bentonite, but some ability to fix elements from leaching may be lost. In addition, ashes from different plants and from different operating periods, as found in this study, can have markedly different properties. To use a particular ash in a liner application, ash must be tested for its behavior to ensure that the correct properties are used in design of the particular liner.

The role of MgO in the binding of SO2 by lime-containing materials

Abstract: The results of investigation of MgO participation in the binding of SO2 with lime-containing materials as sorbents are presented. Experiments of SO2 binding into solid phase using model samples of reactive grade MgO and CaO varying the mole ratio of MgO/CaO from 9:1 to 1:9 were carried out. Besides, dolomite and limestone samples with different MgO/CaO mole ratio (from 1.24 to 0.13) and samples of ashes formed at combustion of Estonian oil shale (containing 35-40% of carbonates) and its semicoke were studied Initial samples, intermediate and final products were subjected to chemical, IR-spectroscopy, X-ray and BET specific surface area analyses. The results of the present study confirmed the active participation of MgO in the binding of SO2 into the solid phase. In addition to CaSO4 the formation of Ca,Mg-double sulphate CaMg3(SO4)4 and β-MgSO4 was observed. The presence of CaMg3(SO4)4 was fixed in a large temperature range 400-900°C and that of β-MgSO4 in between 500-700°C. The optimum temperature range for formation and durability of CaMg3(SO4)4 was 700-800°C.

Solid heat-generating composition

Abstract: A solid heat-generating composition utilizing the heat of hydration of calcium oxide, comprising calcium oxide and a solid substance supplying water capable of reacting with calcium oxide such as a solid substance having water of absorption, adsorption or crystallization, and an organic compound which yields water by an intramolecular or intermolecular reaction at elevated temperature. The composition can be utilized in various applications utilizing heat generation, for example for thawing and heating frozen foods, controlled releasing of agricultural chemicals such as insecticides or repellents, warming human body, etc.

Sintered body of aluminum nitride

Abstract: Sintered bodies of aluminum nitride are produced by adding, as a sintering aid, an oxide mixture consisting essentially of calcium oxide, yttrium oxide and one or more oxides of tungsten oxide and molybdenum oxide or a mixture of compounds (precursors) capable of being converted into said oxide mixture by firing to aluminum nitride as a main component in such proportions that total amounts of the sintering aid is in the range 01 to 20% by weight (calculated as oxides of CaO, Y₂O₃, WO₃, and MoO₃) based on the sum of the weight as the oxide forms of the sintering aid and aluminum nitride, molding the resulting composition and sintering the molded composition The composition can be sintered at relatively low temperature The black sintered bodies thus obtained are especially useful as materials for insulating substrate, heat sink, packaging for semiconductor device, etc, due to their high density and good thermal conductivity