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.

Phase transformation of transient B4C to CaB6 during production of CaB6 from colemanite

Abstract: The aim of this project is the production of calcium hexaboride (CaB6) from colemanite and petroleum coke and the determination of the temperature-dependent phase transformation of boron carbide (B4C), which appears as an intermediate compound to CaB6. This process makes use of the advantages of the “B4C method” as a special case of the “carbothermic method” for the direct production of CaB6 from natural raw materials. Colemanite (2CaO·3B2O3·5H2O), taken from Eti holding Co. in Turkey, and petroleum coke are used as raw materials. As-received crushed colemanite is processed by calcination between temperatures of 400 °C and 600 °C. X-ray diffraction analyses show that the obtained material contains amorphous boron oxide (B2O3) and calcium oxide (CaO) as well as calcium carbonate (CaCO3) and SrSO4 as additional crystalline components. The production of CaB6 was carried out by sintering the powder mixture under argon between temperatures of 1400 °C and 2000 °C. The products were analysed with an X-ray diffractometer. The experimental results and thermodynamic calculations show that B4C is produced as an intermediate product and remains present up to temperatures of 1700–1850 °C as the boron source for the formation of CaB6. The decomposition reactions of B4C to CaB6 in this temperature range were recorded by X-ray diffraction analyses and agree with thermodynamic calculations. It is concluded that the “carbothermic method” can be directly used for the production of CaB6 from the as-received unmilled raw material obtained from the calcination of colemanite at 400 °C and petroleum coke.

Characteristics of lime retention by montmorillonitic clays

Abstract: PREVIOUS WORK HAS SHOWN THAT HYDRATED LIME ADDED TO CLAYEY SOILS REDUCES THEIR PLASTICITY ABOVE A CERTAIN PERCENT LIME THERE IS A LEVELING OFF AND NO FURTHER REDUCTION THE POINT AT WHICH THIS LEVELING OFF BEGINS MAY BE REFERRED TO AS THE LIME RETENTION OR LIME FIXATION POINT THE AMOUNT OF LIME NEEDED TO SATISFY THE LIME RETENTION REQUIREMENT OF CLAYS MUST BE EXCEEDED IF LATER POZZOLANIC CEMENTITIOUS REACTIONS ARE TO PROCEED LIME RETENTION OCCURS IN CLAYS ALREADY CALCIUM SATURATED, ALTHOUGH SODIUM CLAYS TAKE MORE LIME THE TOTAL CALCIUM RETAINED EXCEEDS THE CATION EXCHANGE CAPACITY AS MEASURED BY THE AMMONIUM ACETATE METHOD LIME RETENTION BY CLAYS WERE STUDIED BY MEASUREMENTS OF PLASTIC LIMIT, PH, VISCOSITY, EXCHANGEABLE CALCIUM, AND X-RAY DIFFRACTION THE LIME RETENTION POINT WAS MOST PRONOUNCED IN MONTMORILLONITIC CLAYS, AND COINCIDES WITH A GRADUAL INCREASE IN PH AND A SHARP RISE IN VISCOSITY OF SUSPENSIONS AS MEASURED BY A STORMER PADDLE- ROTATION TYPE OF VISCOSIMETER THE RISE IN VISCOSITY WAS OBSERVED WITH NATURAL SODIUM- AND CALCIUM-SATURATED BENTONITES AND WITH IOWA GUMBOTIL AND PLASTIC LOESS SOILS VISCOSITY DEPENDS ON PH AS WELL AS ON CALCIUM ION CONCENTRATION, AND REACHES A MAXIMUM AT AROUND PH 118 HYPOTHESES OF LIME RETENTION ARE PRESENTED /AUTHOR/

Lanthanum Oxide Effects on the Structure of Calcium Phosphate Glasses

Abstract: Calcium phosphate glasses, in which part of calcium oxide was replaced by lanthanum oxide, were prepared by using the conventional melt quench method. The structures of xLa2O3 · (50-x)CaO · 50P2O5 ...

Polyaluminum calcium hydroxychlorides and methods of making the same

Abstract: A process is provided for the preparation of a novel polyaluminum calcium hydroxychloride composition of enhanced efficiency for water treatment, paper sizing, and antiperspirant applications. The polyaluminum calcium hydroxychloride compositions are prepared via the acidification of higher basicity reaction products to form mid-to-high basicity final products. Two methods are provided for the preparation of higher basicity products, contemplated in the first, and an aqueous acid solution, such as hydrochloric acid, aluminum chloride, or a mixture thereof, is mixed with a strong alkaline calcium salt such as calcium oxide or calcium carbonate and aluminum powder at temperatures greater than 60°C. In a second method, bauxite, aluminum hydrate, or aluminum metal, and calcium aluminate are mixed with hydrochloric acid and are reacted at high temperatures and/or elevated pressures for a certain period of time whereby, when the reaction is complete, the mixtures are filtered to obtain clear solutions. The final PAC-Ca solutions may be dried to powder to have a wide range of basicities from about 40% to about 80%. At lower basicities, the polyaluminum calcium hydroxychloride sales are used preferably as antiperspirants, while at higher basicities, the solutions are used preferably as water treatment chemicals.

Treatment of solid containing material derived from effluent or waste from wastepaper treating process

Abstract: A method of treating solid-containing material contained in or produced from an effluent or waste from a process for the treating of waste paper. The solid-containing material includes constituents of the waste paper and organic material including cellulose fibers and inorganic particulate material including calcium carbonate and other inorganic particulate material included in the waste paper. The solid-containing material is subjected to a heat treatment that incinerates the organic material present and forms from the inorganic particulate material present a calcined product including calcium oxide from thermal decomposition of calcium carbonate. The calcined product is formed into an aqueous suspension wherein calcium oxide is converted to calcium hydroxide. The calcined product in the suspension is comminuted and a reagent is added to the suspension to form a salt-forming anionic species to form an insoluble calcium salt precipitate mixed or aggregated with other inorganic particulate material derived from the waste paper constituents.