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.

Study of a hydraulic dicalcium phosphate dihydrate/calcium oxide-based cement for dental applications.

Abstract: By mixing CaHPO 4 . 2H 2 O (DCPD) and CaO with water or sodium phosphate buffers as liquid phase, a calcium phosphate cement was obtained. Its physical and mechanical properties, such as compressive strength, initial and final setting times, cohesion time, dough time, swelling time, dimensional and thermal behavior, and injectability were investigated by varying different parameters such as liquid to powder (L/P) ratio (0.35-0.7 ml g -1 ), molar calcium to phosphate (Ca/P) ratio (1.67-2.5) and the pH (4, 7, and 9) and the concentration (0-1 M) of the sodium phosphate buffer. The best results were obtained with the pH 7 sodium phosphate buffer at the concentration of 0.75 M. With this liquid phase, physical and mechanical properties depended on the Ca/P and L/P ratios, varying from 3 to 11 MPa (compressive strength), 6 to 10 min (initial setting time), 11 to 15 min (final setting time), 15 to 30 min (swelling time), 7 to 20 min (time of 100% injectability). The dough or working time was over 16 min. This cement expanded during its setting (1.2-5 % according to Ca/P and L/P ratios); this would allow a tight filling. Given the mechanical and rheological properties of this new DCPD/CaO-based cement, its use as root canal sealing material can be considered as classical calcium hydroxide or ZnO/eugenol-based pastes, without or with a gutta-percha point.

Method for manufacturing fatty acid calcium salts from high glyceride content oils

Abstract: A method for the preparation of fatty acid calcium salts, which includes the steps of: (a) providing a fatty acid feedstock having a glyceride content between about 30 and about 60% by weight; (b) adding to the feedstock from about 2 to about 3 equivalents of calcium oxide relative to the feedstock, so that a reactive admixture is formed; and (c) adding to the reactive admixture from about 2 to about 5 equivalents of water relative to the calcium oxide so that the calcium oxide hydrates and neutralizes the fatty acids to form calcium salts. Fatty acid calcium salts containing eicosapentaenoic acid and decosahexaenoic acid are also disclosed, as well as methods for enhancing ruminant fertility.

Improved solidification of aqueous radioactive waste using insoluble compounds of magnesium oxide

Abstract: Firm gel structures are formed from hot aqueous radioactive waste solutions containing boric acid by adding powdered magnesium oxide or magnesium hydroxide followed by addition of calcium oxide or calcium hydroxide. Cement may be introduced after addition of the magnesium compound without interfering with subsequent gel reactions. Product rigidity imparted by the gel enables reduction of typical cement usage up to 50% or more in the processing of radioactive boric acid concentrates. This results in more waste being solidified per container, less exothermic heat generation, greater shipping efficiency, and improved resistance to aqueous leaching of radionuclides.

Novel method for leaching, impurity removing and precipitating ion type rare earth ore

Abstract: The invention relates to a novel method of ion type rare-earth ore leaching, impurity removing and depositing, and the method consists of steps of leaching of ion type rare-earth ore, impurity removing for the rare earth leaching liquid, depositing of the rare earth solution after the impurity removal, rare earth burning and the like.The method is characterized in that a mixed leaching agent consisting of calcium chloride of 1-10% and ammonium chloride of 0.5-2% is added to the ion type rare earth ore leaching pond or in-situ place; using calcium oxide and water with a weight ratio of 1: (2-20) to the rare earth leaching liquid to obtain lime cream the PH of which is then adjusted to 5.0-5.4 and then a impurity removal process is performed; after the impurity removal process, the rare earth is deposited by using a deposition agent which is calcium oxide or a mixer of calcium oxide and seed crystal (the quantity ratio of the rare earth, the calcium oxide and the seed crystal is 1: (2-3) : (1/3-3)l in the rare earth solution, and in a sedimentation tank with seed crystal or added with seed crystal, the PH of the solution is adjusted to 8.0-9.0 by using lime cream to deposit the rare earth.The invention has characteristics of high rate of deposition of rare earth, environment protection by the reutilization of waste water, and further reducing of production cost.

Effect of Calcium Oxide on the Crushing Strength, Reduction, and Smelting Performance of High-Chromium Vanadium–Titanium Magnetite Pellets

Abstract: The effect of calcium oxide on the crushing strength, reduction, and smelting performance of high-chromium vanadium–titanium magnetite pellets (HCVTMP) was studied in this work. The main characterization methods of an electronic universal testing machine (EUTM), X-ray fluorescent (XRF), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), and scanning electron microscope-energy disperse spectroscopy (SEM-EDS) were employed. The crushing strength was affected by the mineral phases generated during oxidative baking and the subsequently-formed pellet microstructures owing to CaO addition. The reduction and smelting properties of HCVTMP with different CaO additives were measured and characterized with different softening-melting-dripping indices. Although HCVTMP showed the highest crushing strength with CaO addition of ca. 2 wt %, more CaO addition may be needed to achieve high permeability of the furnace burdens and a good separation condition of the slag and melted iron. In the formation process of the slag and melted iron, it can be determined that CaO could have a relationship with the transformation behavior of Cr, V, and Ti to some extent, with respect to the predominant chemical composition analysis of ICP-AES and XRF. With the microscopic examination, the restraining formation of Ti(C,N) and the promoting formation of CaTiO3 are in accordance with the improved melting-dripping indices, including the decrease of the maximum external static load and gas permeability, and the increase of the melting-dripping zone and dripping difficulty.