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Catalytic Calcination of Calcium Carbonate

Description: The calcination of calcium carbonate in a cement or a lime kiln uses approximately two to four times the theoretical quantity of energy predicted from thermodynamic calculation depending upon the type of the kiln used (1.4 x 10^6 Btu/ton theoretical to 6 x 10^6 Btu/ton actual). The objective of this research was to attempt to reduce the energy required for the calcination by 1. decreasing the calcination temperature of calcium carbonate, and/or 2. increasing the rate of calcination at a specific temperature. Assuming a catalytic enhancement of 20 percent in the industrial applications, an energy savings of 300 million dollars annually in the United States could be reached in the cement and lime industries. Three classes of compounds to date have shown a positive catalytic effect on the calcination of calcium carbonate. These include alkali halides, phospho- and silico-molybdate complexes, and the fused carbonates system.
Date: August 1985
Creator: Safa, Ali Ibrahim, 1953-
Partner: UNT Libraries

Final technical report for contract year November 9, 1947 to November 9, 1948

Description: Report describing processes to prepare metallic calcium of a very high purity. Report details promising methods for electrolyte purification. Methods of chemical analysis for nitrogen are also improved upon and spectrochemical methods and standards established for twelve other specified elements.
Date: 1948
Creator: Brown, H. & Woodberry, P.
Partner: UNT Libraries Government Documents Department

Response of Freshwater and Saltwater Toxicity Test Species to Calcium and Salinity Concentrations Encountered in Toxicity Tests

Description: The responses of freshwater (Daphnia magna. Pimephales promelas) and saltwater (Mysidopsis bahia. Cyprinodon variegatus) toxicity test species to elevated calcium concentrations and changing salinity conditions were investigated. The use of salinity as a criterion for selection between saltwater and freshwater test species was investigated by conducting both calcium and salinity toxicity tests. Salinity was determined to be an inappropriate criterion under conditions encountered in this study.
Date: 1989
Creator: Price, Edmund E., 1954-
Partner: UNT Libraries

The Isotopic Composition of Trace Quantities of Lead and Calcium

Description: The following report discusses development of new micro-chemical and micro-mas spectrometric techniques for handling trace quantities of lead. The first two sections of this report summarizes the development and trial application to mineral separates of a granite rock. The third section summarizes similar techniques developed for the determination of calcium, and gives the results of an application of the technique to the determination of the radioactive decay constants of K-40.
Date: 1951
Creator: Patterson, Claire
Partner: UNT Libraries Government Documents Department

Effect of Calcium Channel Antagonists and Other Agents on Olfactory Reception

Description: The role of Ca++ in olfactory responses was investigated with inorganic and organic calcium channel antagonists. Electrophysiological responses to odorants were recorded from frog olfactory mucosa before and after aerosol application of different agents. Electroolfactogram responses were blocked by certain inorganic ions with the order of effectiveness Zn++ >Ln+++>Cd++>Ca++>Co++>Sr++>Mg++. Ba++ potentiated olfactory responses, and is known to potentiate calcium channel-mediated responses in other tissues. Certain local anesthetics which are thought to act through calcium channel blockade were inhibitory to olfactory responses, with the order of effectiveness being dibucaine>tetracaine>procaine. These data support the idea that Ca++ is involved in olfaction, perhaps acting as a current carrier and/or a second messenger. Preliminary experiments on channel localization were performed using a silicon-labeled amine. Attempts to localize the silicon label were inconclusive, although silicon was detected in the olfactory tissue.
Date: August 1985
Creator: Rosick, Edward R. (Edward Rudolph)
Partner: UNT Libraries

Calcium Silicates: Glass Content and Hydration Behavior

Description: Pure, MgO doped and B2C3 doped monocalcium, dicalcium, and tricalcium silicates were prepared with different glass contents. Characterization of the anhydrous materials was carried out using optical microscopy, infrared absorption spectroscopy, and X-ray powder diffraction. The hydration of these compounds was studied as a function of the glass contents. The hydration studies were conducted at 25°C. Water/solid ratios of 0.5, 1, 10, and 16 were used for the various experiments. The hydration behavior was monitored through calorimetry, conductometry, pH measurements, morphological developments by scanning electron microscopy, phase development by X-ray powder diffraction, and percent combined water by thermogravimetry. A highly sensitive ten cell pseudo-adiabatic microcalorimeter was designed and constructed for early hydration studies. Conductometry was found to be of great utility in monitoring the hydration of monocalcium silicate and the borate doped dicalcium silicates.
Date: August 1987
Creator: Zgambo, Thomas P. (Thomas Patrick)
Partner: UNT Libraries

CERIUM AND PLUTONIUM DIOXIDE--NOTES ON REDUCTION TO MASSIVE METAL

Description: In reduction reactions of CeO/sub 2/, with calcium and a CaCl/sub 2/ flux, the use of vibrational energy was shown to have a marked effect on the yield of coalesced metal. Buttons of 40 to 50% theoretical yield were obtained from the vibrated reductions. As the flux concentration is decreased, the slag becomes more viscous containing undissolved CaO. The undissolved CaO present prevents the metal from completely coalescing, but the metal can be recovered from the slag and coalesced under CaCl/sub 2/ containing a small amount of calcium to reduce any oxide skin present. Cerium pellet yields of 50 to 60% metal were obtained by the procedure and were not difficult to handle in air. Cerium was used as a stand-in material for plutonium. (B.O.G.)
Date: February 13, 1956
Creator: Tolley, W. B.
Partner: UNT Libraries Government Documents Department

Calcium Aluminates Synthesis, Characterization, and Hydration Behavior

Description: The hydration behavior of the calcium aluminates as a function of the glass content, the curing temperature, and the water-solid ratio was investigated. In order to keep them from influencing the results, the free-lime content and the surface area of all samples were kept constant, whenever possible. Samples were hydrated with a water-solid ratio of 10/1 for periods of 1 to 90 days. Three curing temperatures were studied; 2°C, 25°C, and 50°C. Samples were hydrated in tightly sealed polyethylene containers to prevent reactions with atmospheric carbon dioxide. The hydration was followed by X-ray diffraction and thermal analysis. Only two samples, Hexacalcium Tetra-alumino Magnesium Silicate and Tricalcium Magnesium Dialuminate, were successfully prepared in an amorphous form. These compounds were used to investigate the effect of glass content on the hydration behavior. Results indicate that when the glass content is increased a corresponding increase is found in the percent combined water. Samples hydrated at 25°C were influenced by changes in the glass content to a greater degree than were those hydrated at either 2°C or 50°C. The effect of the water-solid ratio on the hydration behavior of the calcium aluminates was studied using the compounds; Hexacalcium Tetra-Alumino Magnesium Silicate/ and Dodecacalcium Hepta-Aluminate. In general, samples that were hydrated with large water-solid ratios reacted more completely than did those hydrated with small water-solid ratios. The presence of sufficient water to theoretically hydrate the samples to completion did not guarantee that the sample would do so. The curing temperature influenced the hydration behavior to a greater degree than did the glass content or the water-solid ratio. Increasing the curing temperature not only increased the rate of hydration, but, in some cases, also changed the hydration products.
Date: December 1984
Creator: Griffin, Joseph George
Partner: UNT Libraries

The Analysis of TBP Process Streams for Calcium with the Flame Photometer

Description: Summary: A method was found for determining calcium concentrations in TBP process streams in spite of serious interferences bysodium, ferrous, uranyl, sulfate, phosphate, and sulfamate ions as well as by TBP. The precision attainable varied from sample to sample, depending upon its composition. In general, errors of 20% or greater occurred. The smallest determinable amount of calcium was about 10 mg/1.
Date: February 20, 1953
Creator: Brite, D. W.
Partner: UNT Libraries Government Documents Department

New Manufacturing Method for Paper Filler and Fiber Material

Description: The use of fillers in printing and writing papers has become a prerequisite for competing in a global market to reduce the cost of materials. Use of calcium carbonates (ranging from 18% to 30%) as filler is a common practice in the paper industry but the choices of fillers for each type of papers vary widely according to its use. The market for uncoated digital printing paper is one that continues to introduce exciting growth projections and it is important to understand the effect that different types of calcium carbonates have on the paper properties made of 100% eucalyptus pulp. The current study is focused on selecting the most suitable market available calcium carbonate for the production of uncoated Eucalyptus digital printing paper, targeting a potential filler increase of 5% above the currently used filler content. We made hand sheets using 13 different varieties of widely used calcium carbonates [Nine samples of PCC (two rhombic and seven scalenohedral, covering a wide particle size range from 1.2 {micro}m to 2.9 {micro}m), and four samples of GCC (three anionic and one cationic, with a particle size range from 0.7 {micro}m to 1.5 {micro}m)] available in the market followed by a 12” pilot plant paper machine run. The detailed analysis on the main structural, optical and strength properties of the hand sheets found that the most suitable calcium carbonate for uncoated Eucalyptus digital printing paper production is scalenohedral PCC, with a particle size of 1.9 {micro}m for its positive effects on thickness, stiffness, brightness and opacity of paper.
Date: June 26, 2011
Creator: Doelle, Klaus
Partner: UNT Libraries Government Documents Department

Calcium/metal Sulfide Battery Development Program. Progress Report, October 1979 - September 1980

Description: A Ca-Al-Si/FeS2 cell has been developed and has exhibited reasonably stable capacity through 3200 h of operation. This system is expected to be capable of meeting the ultimate performance goals (i.e., 160 W.h/kg) of this development program. Further tests of this cell system in the coming year will better define its ultimate performance capabilities.
Date: March 1981
Creator: Barney, Duane L.; Roche, M. F.; Preto, S. K.; Ross, L. E.; Otto, N. C. & Martino, F. J.
Partner: UNT Libraries Government Documents Department

Recovery of lime from coal gasifier waste containing calcium sulfide

Description: Calcium-based materials hold great promise as sorbents for reduced sulfur compounds at high temperature. Such materials are needed for hot gas clean up or for direct addition to coal gasifiers in several types of integrated coal gasification, combined-cycle (IGCC) power generation systems under development. However, their use has been hindered by the lack of a suitable regeneration process for converting CaS back to CaO. Recently, it was discovered in the laboratory that CaS particles can be converted rapidly and almost completely to CaO by a cyclic process which exposures the material alternately and repeatedly to oxidation and reduction at 900 to 1,100 C. During oxidation with air a small portion of CaS is converted to CaSO{sub 4} which upon treatment with a reducing gas is converted to CaO. By repeating the cycle numerous times, individual particles are converted completely to CaO. Such a process can be carried out in a fluidized bed reactor which either has both oxidizing and reducing zones or is supplied with gas that is alternately oxidizing and reducing. The cyclic oxidation/reduction process for converting CaS to CaO has been demonstrated with a thermogravimetric analysis (TGA) systems, and the results are reported below. The effects of temperature and gas composition on the overall rate of conversion are indicated as well as the effect of subjecting typical sorbent materials to repeated sulfidation and regeneration.
Date: October 1, 1995
Creator: Jagtap, S.B. & Wheelock, T.D.
Partner: UNT Libraries Government Documents Department

Production and Properties of Ceramic Bodies of Alkaline Earth and Other Refractory Oxides

Description: Report discussing the properties and methods of forming ceramic bodies of alkaline earth and other refractory solids. These materials can be used for "reaction chambers, crucibles for melting metals, casting solids, insulation shields, thermocouple shields and other heat resistant bodies...High calcium lime was found to have the necessary chemical and thermal properties for many of the above uses."
Date: August 1945
Creator: Keller, W. H.; Peterson, David & Handlin, Louis
Partner: UNT Libraries Government Documents Department

The Production of Beryllium by the Metallothermic Reduction of Beryllium Fluoride

Description: Report discussing "the production of beryllium by the metallothermic reduction of its fluoride...Charges of BaF2 and Mg reacted smoothly when heated by induction in graphite crucibles and on continued heating the metal and slag separated fairly well. It was found that an addition of CaCl2 to the top of the charge facilitated the separation a great deal. Very clean, massive metal has been produced by this procedure."
Date: September 30, 1945
Creator: Spedding, F. H.; Wilhelm, H. A.; Keller, W. H. & Noher, Charles
Partner: UNT Libraries Government Documents Department

Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers

Description: In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.
Date: August 9, 2006
Creator: Enlow, Drew Lenzen
Partner: UNT Libraries Government Documents Department

Final report for grant number DE-FG02-06ER64244 to the University of Idaho (RW Smith)-coupling between flow and precipitation in heterogeneous subsurface environments and effects on contaminant fate and transport

Description: Engineered remediation strategies for inducing mineral precipitation in the subsurface typically involve the introduction of at least one reactant either by direct injection or by in situ generation. The localization of reactant sources means a wide range of saturation states and ion ratios will be created as reactants are mixed: These conditions together can result in a wide range of precipitation rates, as well as impact which mineral phase precipitates. This is potentially important for the capacity of the precipitates to take up of trace metal contaminants, for their long term stability. Aragonite, for example, is able to sequester a larger amount of Sr than calcite. However, aragonite is less stable under typical groundwater conditions, and so may release sequestered Sr over time as the aragonite transforms to a more stable phase. In addition, previous experimental studies have indicated that other system constituents may influence calcium carbonate precipitation and consequently the Sr uptake potential of a system. For example, dissolved organic carbon (at levels typical of groundwaters) can suppress crystal growth. As a result, the continuous nucleation of small crystals, rather than growth of existing crystals, may be the dominant mode of precipitation. This has the potential for greater uptake of Sr because the smaller crystal sizes associated with nucleated calcite may more readily accommodate the distortion resulting from substitution of the larger Sr ion for Ca ions than can larger crystals. However, these smaller crystals may also be less stable and over the long term release Sr as a result of Ostwald ripening. To better understand the formation and composition of relevant calcium carbonate mineral phases two related series of mineral precipitation experiments were conducted. The first series of experiments, conducted using a Continuously Stirred Tank Reactor (CSTR) operated at steady state rates of precipitation was focused on understanding ...
Date: June 18, 2010
Creator: Smith, Robert W.; Beig, Mikala S.; Gebrehiwet, Tsigabu; Corriveau, Catherine E.; Redden, George & Fujita, Yoshiko
Partner: UNT Libraries Government Documents Department

Role of Calcium and Phospholipids in Transepithelial Sodium Ion and Water Transport in Amphibian Epithelia

Description: The present investigation is concerned with determining the role of calcium, phospholipids, and phospholipid metabolites on transepithelial sodium and water transport in response to antidiuretic hormone (ADH). These studies utilize the frog skin for determining sodium transport and amphibian urinary bladder for water flow measurements and scanning electron microscopy of cell surface morphology. The results demonstrate that phospholipids and phospholipid metabolites containing arachidonic acid stimulate transepithelial sodium transport through amiloride sensitive channels and the action of these lipids involves the synthesis of prostaglandins. These lipids also inhibited the increase in water flow induced by ADH, and this effect was prevented with prostaglandin synthesis inhibitors. Prostaglandins alter intracellular calcium concentrations and agents effecting calcium metabolism alter cell surface morphology and the changes in surface substructure induced by ADH. These observations support the hypothesis that alterations in membrane permeability to water and ions may involve metabolism of membrane phospholipids and prostaglandin biosynthesis.
Date: August 1983
Creator: Tarapoom, Nimman
Partner: UNT Libraries