Showing papers on "Calcium oxide published in 1979"

Lime Columns—A New Foundation Method

Abstract: A new foundation method is described where columns manufactured in situ by mixing soft clay with unslaked lime are used as foundation for light structures to reduce settlements and to increase the bearing capacity. Methods have been developed for the calculation of total and differential settlements based on results from full-scale tests. The lime columns also function as drains in soft clay which increase the consolidation rate of the soil.

Process for converting coal ash slag into portland cement

Abstract: Disclosed is a manufacturing process for converting coal ash slag from a slagging coal gasifier into a marketable cement product having the characteristics and qualities of portland cement. This process comprises the steps of transferring molten slag from a slagging coal gasifier to a melt chamber and reacting it with a mineral containing lime, for example: calcium oxide, calcium hydroxide or calcium carbonate, to form a homogeneous cement product. This cement product is then transferred to a quench chamber where it is allowed to cool and solidify in the form of clinkers, which are later reduced to powder form. This process also provides an efficient means to conserve energy when producing a portland cement and provides an effective and economical way to dispose of a waste product while increasing the cost efficiency of a slagging coal gasifier.

Production of epoxy compounds from olefinic compounds

Abstract: Chlorine and tertiary alkanol dissolved in an inert organic solvent are reacted with calcium oxide in aqueous calcium chloride to produce tertiary alkyl hypochlorite which is recovered in the organic solvent and reacted with water and olefinically unsaturated compound to produce chlorohydrin and tertiary alkanol. Chlorohydrin and tertiary alkanol recovered in the organic solvent are contacted with calcium oxide in aqueous calcium chloride to produce the epoxy compound, and tertiary alkanol recovered in the organic solvent is recycled to hypochlorite production. Calcium chloride produced as by-product in the hypochlorite production and saponification is recovered as an aqueous solution having a calcium chloride concentration of at least 25 wt. % to provide calcium chloride in a usable form.

Calcium silicates: A new class of highly regenerative sorbents for hot gas desulfurization

Abstract: A thermodynamic and kinetic study on the use of calcium silicates and silica-supported lime as regenerative sorbents for desulfurization of hot combustion gases showed that, except for ..gamma..-Ca/sub 2/SiO/sub 4/ and Ca/sub 3/SiO/sub 5/, all the calcium silicates and the silica-supported calcium oxide were as reactive as, or more reactive than, calcium oxide. The regeneration rates of these sorbents were substantially higher than that of calcium oxide, the rate of thermal decomposition of the sulfated mono- and dicalcium silicates being about 15 times higher than that of calcium sulfate. Sulfation rates of CaSiO/sub 3/ and Ca/sub 2/SiO/sub 4/ were first order with respect to sulfur dioxide only for partial pressure of sulfur dioxide Vertical Bar3; 3000 ppm. The silica-supported calcium oxide after heat treatment at 1075/sup 0/C had ..beta..-CaSiO/sub 3/ on its surface.

Method and apparatus for treating water containing wastes

Abstract: A method and apparatus for treating a water containing waste such as industrial sludges and animal excrements. The method comprises a first step of mixing the waste with an alkaline earth metal oxide such as calcium oxide to obtain a preliminarily dried mixture and a second step of further drying and granulation of the mixture. The apparatus comprises a reactor for a mixture of the waste and an alkaline earth metal oxide, a drying kiln equipped with a stirrer means, a furnace surrounding the drying kiln and an exhaust collector means adapted to collect an exhaust gas from the reactor and drying kiln and transfer it to the furnace. Fuel consumption is saved by utilization of the exothermic reaction of an alkaline earth metal oxide with water contained in the waste. The waste may be converted by the method to usable products such as fertilizers, cement materials or cement additives. The apparatus is so designed to overcome the problems of an offensive odor produced during processing and at the same time to minimize a loss of heat during the transportation of the mixture from the reactor to the drying kiln.

Method for manufacturing fire-resistant lightweight building elements with accurate dimensions

Abstract: The invention relates to a method for producing fire-resistant, dimensionally accurate lightweight building boards with a bulk density of about 160 kg / m³ to 800 kg / m³ on the basis of fiber-reinforced calcium silicate materials by reacting amorphous and crystalline silicon dioxide or materials containing them with calcium oxide or materials containing them in a molar ratio of CaO to SiO2 of 0.8: 1 to 1.1: 1 with the incorporation of toxicologically harmless fibrous materials in the presence of water and molding and autoclave hardening, in which, as a further additive, a synthetically produced calcium silicate granulate or powder with a Mol ratio of CaO to SiO2 from 0.8: 1 to 1.1: 1 is used and the reaction before molding (pre-reaction) without external heat application in a minimum time of at least 5 in reverse function to the desired bulk density of the lightweight board to be produced Hours in the case of the manufacture of lightweight panels with a density of 800 kg / m³ to at least 12 hours in the case of the manufacture of lightweight panels with a density of 160 kg / m³ is carried out in increasing numbers.

Kinetics of desulfurization of hot fuel gas with calcium oxide. Reaction between carbonyl sulfide and calcium oxide

Abstract: The reaction between carbonyl sulfide and calcium oxide was studied since the typical concentration of COS is 0.01Vertical Bar3< in the fuel gases from commercially available coal gasifiers. Rates of sorption of 0.1Vertical Bar3< COS in N/sub 2/, with 10Vertical Bar3< CO added to suppress decomposition of COS, were measured at 500/sup 0/-900/sup 0/C, a total pressure of 1 atm and a flow rate of 2000 std cc/min. The CaO sample was a reagent-grade fine powder with a particle size of 1-5 jm. The over-all rates at 600/sup 0/-900/sup 0/C correlated satisfactorily with the grain model (with a shape factor of 1.5), where chemical reaction was the rate-limiting step. The rate of reaction of COS with CaO was first order in COS with an activation energy of 4.3 kcal. The rate of sorption of COS by CaO was slightly higher than that of H/sub 2/S, using the literature data on the H/sub 2/S sorption. Significant sorption of COS takes place parallel to the sorption of H/sub 2/S in the coal gasification processes in which lime is used.

Methods for consolidating radioactive waste material using self-setting or water-settable compositions containing an organic polyisocyanate, a non-ionic surface active agent devoid of isocyanate-reactive groups and alkaline filler

Abstract: Self-setting compositions are formed by bringing into admixture an organic polyisocyanate, a non-ionic surface active agent devoid of isocyanate-reactive groups, an alkaline filler and water. Preferred alkaline fillers are portland cement, calcium oxide and hydrated lime. A plasticizer is preferably incorporated in the composition. Waste material, for example liquid or particulate radioactive wastes may be formed into a self-setting composition for consolidation and disposal. A particulate extender may be incorporated in the self-setting composition to give a product useful for example as a floor screed or cavity filler.

Method of producing a complex mineral fertilizer

Abstract: A method of producing a complex mineral fertilizer is disclosed, comprising the steps of decomposing polyhalite at a temperature not exceeding 110° C. in the presence of dilute nitric acid, neutralizing the obtained suspension with a substance selected from the group consisting of calcium carbonate, calcium hydroxide and calcium oxide, and separating the resultant product.

Method for production of alkali metal chromates from chrome ores

Abstract: A method for producing alkali metal chromates by a single roast of chrome ores without the use of calcium oxide is disclosed. A double roast embodiment is also contemplated for obtainment of enhanced yields. The pollution and hygiene problems associated with the use of lime are substantially eliminated and only negligible amounts of alumina are found in the product chromate liquors without employing steps previously thought necessary. These advantages are achieved by controlling (1) the Bichromate Equivalent: aluminum oxide ratio in the mix, (2) the amount of alkali metal salts added to the mix, (3) the roasting time, (4) the composition and alkalinity of the liquor used for leaching the roast, and (5) the temperature employed. Recovery of vanadium values from the alkali metal chromate liquors is also disclosed.

Process for plant scale production of cement with mechanical compounding

Abstract: A process for plant scale production of cement wherein the materials including at least calcium oxide, silicon dioxide and aluminum oxide are subjected to the steps of grinding to approximately a 200 mesh size, drying to less than 5% water by weight of the materials when mixed, blending to a uniform mixture and compounding in a high velocity compounding mill.

Process for preparing mold

Abstract: A mold with an increased compression strength and a good collapsibility is prepared with a good efficiency by mixing refractory particles with a binder material comprising a caustic alkali-neutralized product of a copolymer containing a carboxyl group and calcium hydroxide, thereby preparing molding materials, filling the molding materials around a pattern, and blowing CO 2 gas into the mold sand, thereby hardening the molding materials. Polyvinyl alcohol, calcium oxide, at least one hydroxide of zinc, aluminum, barium, magnesium, and iron, SBR latex, etc. can be added to the binder material, when desired.

Engineering Properties of Soil-Lime Mixes

Abstract: The relation between sample preparation and curing procedures, and the engineering properties of compacted soil-lime mixes was investigated. Four natural Oklahoma soils of different origins were used in this study. The effects of variation of lime content, water content, and curing environment factors were evaluated on the basis of the strength, permeability, and pH of compacted specimens. It was found that the compressive strength increases with increasing lime content. Strength improvement was most conspicuous in the samples compacted at moisture contents above the optimum; the strength of samples compacted at lower moisture content could usually be improved by increasing the availability of water during curing. The soil pH appears to be an important factor controlling the soil strength, but its influence is better regulated by the lime-water ratio than by lime-soil ratio. The permeability of all soils was increased by the addition of lime, but the effect is reduced when water is sprinkled on the compacted lifts prior to curing.

On the Formation of O−2 Ion on Calcium Oxide

Abstract: — 6]. However, the interaction of the oxide surface with molecular oxygen are the subject of some controversy. At first, it was believed that the formation of 02 on MgO could be attained only by or UV irradiation [7,8]. Later, Derouane and Indovina [9] reported the formation of OJ ion on thermally activated MgO powders without need of prior irradiation. Indovina and Cordischi [10] found that the activity for 02 ion formation was enhanced when the sample was first exposed to H2, CO or C2H4 at room temperature. As for the oxygen adsorption on CaO, Iizuka and Tanabe [11] found a broad unsymmetrical signal when CaO with preadsorbed pyridine

Process for producing an aquous suspension of calcium and/or magnesium carbonates from dolomite

Abstract: 1. A method of producing an aqueous suspension of carbonates of calcium or/and Magnesium from dolomite, wherein the dolomite is converted into a mixture of calcium oxide and magnesium oxide by heating to approx. 1000-1100 degrees C, whereafter the resultant oxide mixture is suspended in water in the proportion by weight of at least 20 parts of water to 1 part of the oxides and wherein the hydroxides which form in the suspension are converted back to the corresponding carbonates by the introduction of carbon dioxide according to DE-A-26 00 485 characterized by that the carbonate-containing suspension is heated to a temperature above 160 degrees C in a pressurized vessel suitable for hydrothermal treatment and maintained at such temperature until lamellar, basic magnesium carbonates of a Shape factor of less than 1 : 30 have formed.

Resin composition for medical instrument construction

Abstract: PURPOSE: To provide a resin compsn. with reduced hemolytic effect and cytotoxicity, by a method wherein finely divided magnesium oxide or calcium oxide powder is blended with a mixt. of a vinyl chloride resin and an ethylene-carbon monoxide- vinyl acetate copolymer. CONSTITUTION: 5W200pts.wt. of an ethylene-carbon monoxide-vinyl acetate copolymer and 0.01W10pts.wt. of finely divided magnesium oxide or calcium oxide powder are blended with 100pts.wt. of a vinyl chloride resin. The ethylene-carbon monoxide-vinly acetate copolymer used is one resulting from the copolymerization of 0.03W5pts.wt. of carbon monoxide and 0.1W0.9pts.wt. of vinyl acetate with 1pt.wt. of ethylene. When the amount of said copolymer is less than 5pts.wt., flexibility can not be obtd. When the amount of said copolymer is more than 200pts.wt., the compsn. is too flexible and is difficult to retain its shape. When the amount of magnesium oxide or calcium oxide is more than 10pts.wt., transparency and flexibility are deteriorated. COPYRIGHT: (C)1981,JPO&Japio

Manufacture of calcium carbonate dispersions in lubricating oil

Abstract: Calcium oxide and carbon dioxide were allowed to react in an organic liquid in the presence of dispersing agents. Calcium carbonate was produced in a finely divided form. Carbonation did not occur unless small quantities of chloride ion were present. The size of the carbonate particles depended on the nature of the cation in the chloride additive and the amount of methanol present. Other factors which affect the size of the carbonate particles are discussed.

Testing tube construction for measuring sodium hydroxide and/or calcium oxide

Abstract: A testing tube for measuring sodium hydroxide and/or calcium oxide aerosols, comprises, a glass tube having breakoff points at each end to open at each end and containing a front layer of a substrate material impregnated with ammonium chloride and a following indicating layer of a substrate material impregnated with an acid and bromphenol blue.

Reclaiming scrap of rare earth magnets

Abstract: PURPOSE: To recover and reclaim rare earth metals in high yield and at a low treatment cost by a method wherein calcareous material is used to reduce oxides in scraps of rare earth magnets and at the same time contained carbon is transformed into calcium carbide and removed by washing with water. CONSTITUTION: To scraps such as powder of ground magnetic earth magnets, calcium in the form of metallic calcium or calcuim hydride is added in an amount of 1.2W2.5 times the stoichiometric amount required for combining oxygen and carbon contained in the scrap. The mixture is formed by compression and charged in a reducing furnace, etc. and heated to about 1,100°C in argon stream so that contained oxygen is transformed into calcium oxide and contained carbon into calcium carbide. The formed body is cooled, crushed, and washed with water to remove calcium oxide and calcium carbide. Dehydration and drying of this powder provides a reduced magnetic powder which, as it is, can be reused as raw material for rare earth magnets. COPYRIGHT: (C)1981,JPO&Japio

A thermoanalytical study of the interaction of vanadiumoxide(v) with calcium oxide and calcium carbonate

Abstract: The interaction of V2O5 with calcium oxide and calcium carbonate was studied by thermal analysis. The results indicated that the macrosuccession of the phase transformations in the systems CaO-V2O5 and CaCO3-V2O5 corresponds to an increasing calcium content in each successively formed calcium vanadate. Thermodynamical calculations carried out by methods available in the literature for determining the primary products and the succession of the subsequently formed products demonstrate that chemical reactions proceeding in the above systems are controlled by kinetic and not by thermodynamic factors.

Gasification of coal liquefaction residues

Abstract: A method for gasifying the bottoms fraction from a coal liquefaction process by mixing the bottoms fraction with at least one finely-divided calcium compound selected from the group consisting of calcium oxide, calcium carbonate and calcium hydroxide with the calcium compound being of a size consist no larger than about -200 Tyler mesh and present in an amount sufficient to produce agglomerate particles upon mixing with the bottoms fraction and thereafter gasifying the resulting agglomerate particles by reacting the agglomerate particles with steam in a fluidized bed.

Method for producing granules or powder of calcium silicate with a micro-porous structure

Abstract: 1. A process for the preparation of calcium silicate granulates or powders, respectively, having a microporous structure by reacting crystalline and optionally amorphous silicium dioxide or materials containing this or these, respectively, with calcium oxide or materials containing this, respectively *, in a molar ratio of CaO to SiO2 of 0.8:1 to 1.1:1 with homogenizing them by dispersing the solid starting materials in water with adding an anion-active surface-active substance previously converted to a foam in water in the presence of air and by shaping and autoclave indurating, characterized in that one uses as a foam a microporous stabile foam which has been produced from a solution of an anion-active surface-active substance prepared by dilution with water in finest distribution in compressed air and has a liter weight of from 30 to 80 g/l the anion-active surface-active substance being employed in an amount of from about 300 to 600 g/m**3 finished product and one works without aggregate as well as one comminutes, dries and classifies the indurated product in a manner known per se.

Process for the manufacture of foamed or non-foamed compositions

Abstract: The present invention relates to a process for the manufacture of foamed or non-foamed compositions, in which one or more organic or inorganic compounds containing at least two isocyanate groups is or are reacted in the presence of an alkaline aqueous solution, an alkaline aqueous suspension or an alkaline aqueous slurry of an alkali metal hydroxide and/or alkaline earth metal hydroxide, and of one or more catalysts and, optionally, inert fillers and/or, optionally, one or more volatile substances as blowing agents. According to the invention, a mixture of the compound or compounds containing the isocyanate groups and the alkali metal hydroxide or oxide and/or alkaline earth metal hydroxide or oxide is added to a mixture of water and catalyst. The oxide employed is preferably calcium oxide.

New approach to predict lime reactivity of soils

Abstract: The purpose of this paper is to provide a nondestructive technique that can be used to evaluate the lime reactivity of a soil from the long-term strength developed in lime stabilized soils in a short-term test. The method proposed is based on the dielectric dispersion properties of clay-water electrolyte system. The properties of treated and untreated soil samples were compared and the difference between them was found to correlate with lime reactivity, i.e. the greater the difference after 1 day cure, the higher the strength after 7 and 28-day cure.

Caluciummbased water treating agent

Abstract: PURPOSE:To provide a water treating agent effective for the removal of water- soluble polymer substances which are difficult to remove such as starch and polyvinyl alcohol. CONSTITUTION:A calcium compound which forms calcium oxide when baked such as calcium hydroxide, calcium carbonate, or calcium chloride is mixed with an aluminum compound which forms aluminum oxide when baked such as aluminum hydroxide, aluminum chloride, or aluminum nitrate and the mixture is baked at a temperature within the range of 1200 to 1600 deg.C. The mixture is so prepared that the weight ratio of calcium oxide to aluminum oxide is between 40/60 and 85/15, preferably between 70/30 and 80/20. This constitution results in the formation of a desired water treating agent.

Removal of sulfur during the combustion of coal by adding limestone

Abstract: The main objective of this paper has been to formulate a mathematical model for the study of the absorption of SO/sub 2/ in limestone, based on a detailed description of the fundamental chemical and physical steps. In particular, an original chemical mechanism has been proposed. It hypothesizes that the sulfur dioxide is oxidized to sulfur trioxide in the combustion chamber because of the catalytic action of tract compounds such as V/sub 2/O/sub 5/ and Cr/sub 2/O/sub 3/ in the coal. Then SO/sub 3/ diffuses into the calcium oxide particles to form calcium sulfate. This mechanism seems to account for the behavior of the desulfurization efficiency in terms of the parameters of interest, as found in experimental work.

Synthetic CO2 acceptor and gasification process therewith

Abstract: A synthetic CO 2 acceptor comprising at least one compound selected from the group consisting of calcium oxide and calcium carbonate supported in a refractory carrier matrix of the general formula 3CaO(SiO 2 ) x (Al 2 O 3 ) 1-x wherein x is from about 0 to about 1.0.