Showing papers on "Calcium oxide published in 1982"

Effect of the clay fraction on some mechanical properties of lime-soil mixtures

Abstract: Artificially prepared, lime-treated mixtures of sand-clay were studied in the laboratory. The experimental programme was arranged with two types of clay mineral (kaolinite and montmorillonite), three levels of clay content (10,30 and 50 per cent), four levels of lime content for the kaolinite soils (0,2,4,8 per cent) and five levels for the montmorillonite soils (0,2,4,8,12 per cent). Two periods of curing (seven and 28 days) were employed. Firstly the maximum dry density optimum moisture content relationships for the 27 different mixtures were determined using one compactive effort. Test specimens for these mixtures were then fabricated at their corresponding optimum compaction conditions. The effect of the type and content of the clay fraction on the specimens' compressive strength, Q, cohesion, C, angle of internal friction, phi, and elastic modulus, e, was determined. The results showed that regardless of the clay content in the soil, increases in the values of q, C, and e due to lime-treatment are significantly higher for the montmorillonite than for the kaolinite specimens. Generally the most significant increase in any of these parameters occurs at two per cent lime for the kaolinite specimens, while for the montmorillonite specimens these strength parameters tend to develop progressively with lime content up to about eight per cent or even beyond. The pattern of increase in the angle of internal friction due to lime treatment is comparable for the two types of soil. The most significant increase occurs mostly up to two per cent lime where it reaches about 10 degrees. Good correlations between unconfined compressive strength and both cohesion and elastic modulus were observed. Linear regression equations for the prediction of and e for lime-treated soils from known values of g were accordingly established. (Author/TRRL)

Hard solid animal feed supplement

Abstract: The invention is a sugar solution-based, preferably molasses-based, animal feed supplement which is produced as a viscous liquid that is gelled into a hard solid by the addition of a soluble calcium salt or oxide, preferably calcium oxide, a soluble phosphate, and a substantial quantity of magnesium oxide. Prior to its solidification a limited amount of discrete cellulose fibers can also be added to reinforce the solid and prevent its cracking. The solid product is hard and water resistant and has a limited consumption rate.

The Use of Additives to Improve the Mechanical Properties of Gypsum Products

Abstract: The effects of adding a combination of calcium oxide and gum arabic additives to calcium sulfate hemihydrate have been determined. It has been found possible to produce gypsum products with properties superior for dental applications. In particular, formulations are suggested for die, model, and flasking materials.

Sodium chloride as an additive in lime-soil stabilisation

Abstract: Kaolinitic and montmorrillonitic soils were prepared from commercial quality sand and clay in 10, 30 and 50 per cent clay contents. Lime was added in 2, 4 and 8 per cent by dry weight of soil. The effect on optimum moisture content, maximum dry density and unconfined compressive strength of adding 1, 2 and 3 per cent of sodium chloride during lime treatment was investigated. At 28 days strength gains due to sodium chloride were generally higher in lime-kaolinite than in lime-montmorillonite soils. These amounted to between 100 and 300 per cent increase in unconfined compressive strength over that of the untreated or lime-only treated soils for clay contents between 30 and 50 per cent of the total soil composition. For most soils the optimum salt content for a maximum strength gain appears to be approximately one per cent. (Author/TRRL)

Water-activated exothermic chemical deicing formulations

Abstract: Chemical formulations containing calcium oxide, or unslaked calcined limestone, and a chemical deicing agent. The formulations liberate heat upon contacting ice or snow and materially assist the normal deicing function. Deicer options include calcium acetate, sodium acetate, magnesium acetate, and potassium acetate and sodium chloride (salt). The magnesium acetate containing formulation represents a special case in which the ultimate products formed are magnesium hydroxide and calcium acetate, both relatively harmless to the environment.

Water-activated exothermic chemical formulations

Abstract: Intimately mixed dry chemical formulations consisting of (1) a stable acid-acetate salt and (2) a chemical base for use as water-activated exothermic deicing agents, and/or as the dry chemical components of a warming device. The salt is optionally calcium monoacid acetate, sodium diacetate, or calcium magnesium monoacid acetate wherein up to 7 mol percent of the metal is magnesium. The chemical base is optionally calcium oxide or hydroxide, magnesium oxide or hydroxide, or calcined limestone. The relatively non-polluting formulations are pelletized or otherwise aggregated for application to roads, highways, walkways and parking lots as deicers.

Method of producing iron-, nickle-, or cobalt-base alloy with low contents of oxygen, sulphur, and nitrogen

Abstract: The disclosed method of producing an iron-, nickel-, or cobalt-base alloy with low contents of oxygen, sulphur, and nitrogen comprises steps of melting the alloy in a crucible lined with a basic refractory containing at least 40% of calcium oxide; and adding at least one additive and not more than 5% by weight of at least one flux, based on said alloy, the additive being selected from the group consisting of aluminum, aluminum alloys, silicon, silicon alloys, titanium, zirconium, niobium, boron, and rare earth elements, the flux being selected from the group consisting of oxides, silicates, carbonates, and halides of alkali and alkaline earth metals, and aluminum oxide, so that the resultant molten alloy contains 0.005 to 7.0% of aluminum, 0.005 to 7.0% of silicon, and 0.0005 to 0.005% of calcium.

Lime mix stabilises subgrade

Abstract: The top 315mm of a Northampton Road subgrade has been transformed into a capping layer conforming to government specification by mixing 3% quicklime into soft in situ clay. The required fifteen-fold increase in CBR values was achieved in less than seven days and the lime will continue to strengthen the clay for several months. Although North America and Europe currently stabilise clay and subgrades with lime as a matter of course, for some reason the method has never been popular in Britain. Provided the clay was treated to a depth of 350mm, the type I sub-base could be reduced from 430mm to 150mm due to the stabilised clay forming the capping layer. Once the contractor had removed the topsoil and excavated to formation level, stabilisation of the 2.5km long 7.3M wide formation was completed in 12 days. Details are given of the lime spreading operation and the mixing process performed by a self-propelled fully hydraulic Bomag MPH 100 pulverising machine specially designed for stabilising operations. A brief explanation of the chemical/physical principles behind the process is included. Amongst the conclusions listed are: that it is worthwhile testing the soil acidity before lime quantities are established; and the formation is probably sufficiently strong after its second pulverization to allow immediate placing of the sub-base. The environment benefitted greatly by utilising local material and so reducing the amount of haulage traffic. (TRRL)

Liming fish ponds

Abstract: PROBLEMS with acid-base relationships in fish ponds can often be solved by liming, which is not a form of fertilization ( 8 ) but a remedial procedure to improve conditions for fish production. Fish will not survive in ponds with water having a pH below 4. Where pH is between 4 and 5.5, fish will survive, but they will not grow and reproduce at normal rates (24). In many ponds with slightly acidic waters (pH 5.5-7) and acidic muds (pH 4-5.5), fish will grow and reproduce, but attempts to increase fish production by inorganic fertilization are seldom very effective (25). The diminished response to fertilization apparently results from insufficient carbon in the alkalinity system to support high rates of phytoplankton photosynthesis and rapid adsorption of phosphate in fertilizers by muds (4). Liming materials Common liming materials include agricultural limestone, calcium hydroxide, calcium oxide, basic slag, and liquid lime. Liquid lime, an aqueous suspension of finely pulverized agricultural limestone, reacts quickly with acidity. Because liquid lime is about 50 percent water, application rates are usually twice those of ordinary agricultural limestone. The term “neutralizing value” refers to the relative abilities of liming materials to neutralize …

Process for manufacture of metallic magnesium

Abstract: A process for manufacture of metallic magnesium. A mixture of a first quantity of magnesium oxide, a second quantity of a carbide forming material which is either a material selected from the group of materials consisting of calcium, aluminum, boron, silicon, calcium oxide, aluminum oxide, boron oxide, and silicon oxide, or is a mixture of two or more of these materials, and whose weight is 10% or less than the weight of the first quantity, and a third quantity of carbon which is at least the equivalent mol weight of that of the magnesium oxide plus the carbide forming material, is heated within a reducing furnace at a pressure between about 5 and 200 torr and at a temperature of at least 1600° C. The carbide forming material combines with the carbon to form carbide, which induces simultaneous reducing reaction as that by carbon and reduces the magnesium oxide, releasing magnesium vapor, which is rapidly cooled down by adiabatic expansion to generate metallic magnesium, while the carbide forming material returns to oxide form. The carbide forming material is recycled again, to repeatedly form carbide and repeatedly reduce more magnesium oxide.

Syntheses of Sodium-Calcium Zeolites at Atmospheric Pressure and 80 °C. I. Reagents Used: Na4SiO4, Al(OH)3, Ca(NO3)2

Abstract: Sodium-calcium zeolite minerals were synthesized in an electric oven at 80 °C for 1–5 weeks from suspensions of a suitable combination of the starting materials, which had a chemical composition of 2nNa2O·2CaO·Al2O3·nSiO2·xH2O(4≤n≤20, x=83–610) All of the synthetic products were obtained as massive products in the gel X-Ray and IR analyses and a quantitative analysis of the principal ingredients showed these massive products to be well-crystallized hydroxycancrinites which contained 0–49% calcium oxide

Processes for the production of slaked lime and magnesium hydroxide

Abstract: Slaked lime (calcium hydroxide) is obtained by contacting quicklime (calcium oxide) with an aqueous solution containing at least one anion selected from the group consisting of Cl, Br and NO 3 ions in a concentration of about 0.1 to about 5 mole/liter at a temperature of about 10° C. to about 65° C. Magnesium hydroxide can be produced by reacting the aforesaid slaked lime with magnesium chloride or magnesium nitrate in an aqueous medium, the amount of slaked lime being about 0.5 to about 0.95 equivalent per equivalent of the magnesium compound, and thereafter heat-trating the reaction product in an aqueous medium at a temperature of about 150° C. to about 250° C.

Process for preparation of gypsum shapes

Abstract: A process for preparing shaped articles from waste gypsum from wet-process phosphoric acid production comprises: (1) mixing wet calcium sulfate hemihydrate with 0.5-20% by wt. of calcium hydroxide or calcium oxide, (2) adjusting the total water content of said mixture to 20-40% by wt., if necessary, and (3) molding shaped articles from said mixture by compression molding. The shaped objects so prepared have a low density and relatively high compressive strength.

Effect of electric fields on solid-state reactions between oxides: Part 4 Interdiffusion in polycrystalline calcium oxide and silicon dioxide pellets

Abstract: Interdiffusion in sintered polycrystalline pellets of CaO and SiO2 occurs predominantly by migration of Ca into SiO2 and is influenced by the application of d.c, electric fields which increase the penetration distance when the silica is negatively charged, and markedly decrease the diffusion when the polarity is reversed. Pseudowollastonite (α-CaSiO3) is formed in the interfacial region of the silica pellets under all conditions, withβ-Ca2SiO4 also appearing in the SiO2 (−ve) electrolysed samples, possibly as a result of stabilization by the excess Ca present which also occurs as CaO interpenetrating the silica pellet. Diffusion coefficients estimated for both the unelectrolysed and field-assisted (SiO2−ve) samples are similar to those for Ca diffusion inα-CaSiO3, but samples electrolysed under reverse polarity conditions (SiO2 + ve) have a much larger diffusion activation energy. The effective electrical mobilities of Ca in the CaO-SiO2 system derived from these results are discussed.

Process for recovery of aluminum from carbonaceous waste products

Abstract: A carbonaceous waste product, preferably containing 30 to 60% mineral substances, 35 to 55% carbonaceous materials, 5 to 20% water, and having a calorific value of 2,000 to 3,500 k cal/kg is fired to produce thermal energy and a combustion residue. The residue is adjusted, if necessary, by addition of mineral containing additives so that it contains 15 to 50% alumina, 15 to 20% silica and 13 to 45% other oxides (mainly iron oxide, manganese oxide and calcium oxide). Sufficient limestone is added to produce a mixture containing 1.8 to 2.2 moles of calcium oxide per mole of silica and 1.1 to 1.3 moles of calcium oxide per mole of alumina. The mixture is then sintered. The total energy requirements of the sintering step are supplied by the energy generated in the firing step. Useful products such as cement and cast stone can be produced from the sintered product.

Fluorine-free calcium-aluminosilicate glasses

Abstract: The invention relates to calciumaluminosilicate glasses. The glasses contain, in weight percent, 25 to 35% silica, 27 to 35% calcium oxide, 25 to 40% alumina, 0 to 4% of alkali metal oxide selected from lithium oxide, sodium oxide and potassium oxide, and 0 to 5% of titanium oxide and a total content of lithium, sodium, potassium and titanium oxides of 0.5 to 9%. The glasses, in finely divided form, react with aqueous polycarboxylic acids and set to a solid mass; cements made from the glass and polycarboxylic acids are useful in splinting compositions.

Alkali earth metal oxide-based coating compositions

Abstract: A noncarbonated complex for use in preparing coating compositions is comprised of the reaction product of a basic oxide selected from the group consisting of calcium and magnesium oxide and mixtures thereof; an organic sulfonic acid having an equivalent weight of about 300 to 750 grams per equivalent; and water. The molar ratio of basic oxide to organic sulfonic acid is at least 10:1. The molar ratio of water to basic oxide is less than 2.5:1 and greater than 0.5:1 when the basic oxide is at least 30 percent calcium oxide. The molar ratio of water to basic oxide is less than 0.7:1 and greater than 0.3:1 when the basic oxide is less than 30 percent calcium oxide.

Process for the desulfurisation of flue gases

Abstract: In this process for dry flue gas desulphurisation, reagents (calcium carbonate, magnesium carbonate, calcium oxide, magnesium oxide, etc.) of a grain size distribution are used, whose maximum is either at larger or at substantially smaller grain diameters than the maximum of the fly ash leaving the vessel (Figures 1 and 2). By selecting suitable separation equipment, this fly ash/reagents mixture is separated in such a way that a mass flow predominantly containing fly ash and a mass flow predominantly containing reagents are formed. The mass flow predominantly containing reagents can be taken to an industrial use or, in order to increase the utilisation of the reagents employed, be recycled to the furnace. If the maximum of the grain size distribution of the reagents employed is at a larger grain diameter than the maximum of the grain size distribution of the fly ash, it is advantageous to grind the mass flow which predominantly contains reagents, before it is re-used, and thus to obtain a substantially smaller grain size distribution. This process variant was illustrated in Figure 4. It is to be noted here that the unburned matter which is found in the fly ash in the case of the large grain diameters of the grain size distribution, is appropriately recycled to the combustion.

Electric joint material

Abstract: A joint material that is improved in arc-proof characteristic, fusion-proof characteristic, and consumption-proof characteristic The joint material contains silver, lithium oxide and one selected from the group consisting of aluminium oxide, calcium oxide, magnesium oxide, and silicon oxide Furthermore, one selected from the group consisting of iron, nickel and cobalt may be contained as an additional component in the joint material Such joint material is produced by a method of oxidizing the silver alloy containing lithium and one selected from the group consisting of aluminium, calcium, magnesium, and silicon, with the composition ratio of 01-3 wt % for lithium, and 001-1 wt % for aluminium, calcium, magnesium, and silicon, respectively, in quantitive conversion to metal or by a method of oxidizing the silver alloy containing, in addition to the components mentioned above, one selected from the group consisting of iron, nickel, and cobalt, with the composition ratio of 005-1 wt % In either of those methods, the oxidization mentioned above is performed through internal oxidation in order to disperse each of the foregoing oxides in silver

Short term active soil property changes caused by injection of lime and fly ash

Abstract: This paper describes research into the physical and chemical property changes that occur in an active clay soil during and shortly after injection witth lime and fly ash slurries. It reports on the changes measured for 20 properties by using 112 samples taken both before and after injection. It describes the design of the experiment, where four treatments were randomly applied in four replications. It describes the property changes noted that were significant and explains how the monitored ground surface elevations changed during the project. The paper describes the processes used for statistical analyses of property changes measured. This description includes two types of analysis of variance and comparison of means before and after treatment. Those properties concluded to have significantly been affected by injection stabilization included water contents, plastic indices, swelling potential, cation exchange capacities, calcium levels in pore water, and calcium levels in the exchange complex. The ground level monitoring analyses presented support the stabilizing effects of lime slurry pressure injection (LSPI). Conclusions include the relative ranking of the treatments applied where a single LSPI followed by a three-staged water injection proved most effective. (Authors)

Reaction products of lime-treated southeastern soils (abridgment)

Abstract: Six soils series (Cecil, Chewacla, Eutaw, Sumter, Tatum, and Wilcox) of the southeastern United States were investigated by using x-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscope. The study compared the natural soil with lime-treated soil (by using 6 percent high-calcium-hydrated lime) after a 48-h accelerated curing period at 49 degrees C (120 degrees F). The compaction specimens were prepared in a Harvard miniature compaction mold by using impact compaction and were sealed in plastic wrap during the curing phase to prevent moisture loss. Lime-soil reaction products of calcium oxide-alumina oxide-hydrate (C4AH3), C3AH6, calcium-silicate-hydrate (CSH) (gel) and CSH II were indentified, although a different mixture of products was associated with each soil. Unknown products were also noted on the thermogravimetric analysis data at 440 degrees, 450 degrees, and 460 degrees C. Both absorbed-solution and through-solution mechanisms appear to be involved in the formation of cementitious material. When compared with lime reactivity (i.e., unconfined compressive strength gain following the accelerated curing), the results for the montmorillonite dominated soils (Eutaw and Wilcox) suggest that excessive specific surface is a detriment to the development of significant cured unconfined compressive strength gains. (Authors)

Stepwise Complexometric Determinations of Calcium and Magnesium in Lime and Magnesia Bearing Materials

Abstract: A simple and rapid complexometric method for stepwise titration of calcium and magnesium, when present in unfavourable ratios, has been successfully worked out. The method is based on the direct titration of calcium of pH 12 with EDTA, using thymolphthaleincalcein indicator. The adsorption of metallochromic indicator and any Ca2+ has been prevented by the prior addition of titan yellow which masks magnesium by lake formation. Glycerine is also added as a protective colloid to stabilize the lake and to prevent coprecipitation of Ca(OH)2. After dissolution of the lake in HC1 acid, subsequent addition of ascorbic acid, then ammonia and ammonia buffer, for controlling the pH at 10, Mg is determined in the same aliquot by direct titration with EDTA using Eriochrome Black T indicator. The method has been successfully applied for the determination of calcium oxide and magnesium oxide in magnesite, dolomite, asbestos and other lime and magnesia bearing materials.

Deoxidizing desiccating agent

Abstract: PURPOSE:To obtain a chemical agent having the effects of a desiccating agent and a deoxidizing agent by adding iron to calcium chloride, and compounding sodium carbonate therewith then adding calcium oxide as a deoxidizing desiccating agent. CONSTITUTION:Iron is added to calcium chloride, and sodium carbonate, active carbon and pearlite or Sirasu balloons are compounded therewith, after which calcium oxide is added whereby the deoxidizing desiccating agent is prepd. This chemical agent is provided with both of deoxidizing power and desiccating power and prevents the danger such as of breaking of the bag by the absorption of water of calcium oxide and liquefaction by the deliquescence of calcium chloride.

Desulfurizing of reducing gas stream using a recycle calcium oxide system

Abstract: A process for producing a low-sulfur content hot reducing gas stream comprising (a) contacting a sulfur bearing hot reducing gas stream with a desulfurizing agent comprising a desulfurizing fixed bed of solid particles comprising calcium oxide to thereby produce a low-sulfur content hot reducing gas stream and a calcium sulfide composition, then (b) contacting said calcium sulfide composition with an oxidizing gas composed of CO 2 , H 2 O and O 2 to thereby convert the sulfide of the composition to a regenerated calcium oxide, and sulfur dioxide and then (c) reusing the regenerated calcium oxide in step (a) to desulfurize a hot reducing gas, and further involving the improvement comprising avoiding the formation of calcium sulfate when regenerating said calcium sulfide composition by means of (a) a separate clean-up bed after the desulfurizing bed of step (a) to assure complete conversion of the calcium oxide to calcium sulfide in the desulfurizing bed, or (b) passing the oxidizing gas through the partially sulfided desulfurizing bed from a direction which minimizes the contact of any sulfur dioxide formed in the regeneration step with any unsulfided calcium oxide.

Preparation of sorbitol adduct with calcium

Abstract: PURPOSE:To obtain the titled adduct useful as a calcium agent in the fields of medicines and food industry in high yield, by reacting an aqueous solution of sorbitol of high concentration with CaO or Ca(OH)2 at specific respective suitable temperatures, and drying and powdering the reaction solution. CONSTITUTION:Calcium oxide powder is dissolved and reacted with an aqueous solution of sorbitol in a concentration of 50-85% while heating the solution at 70 deg.C or above under stirring, or calcium hydroxide is added and reacted with an aqueous solution in a concentration of 60-100% or a melt thereof at 40- 140 deg.C. The reaction solution is directly dried or concentrated and dried to give a powder and give the aimed sorbitol adduct of calcium. In case calcium oxide is used as the raw material, hot water is added to the reaction solution, and filtered while hot to remove the unreacted calcium oxide or formed calcium hydroxide. The resultant filtrate is then cooled, crystallized and separated to give the aimed substance.

Treatment of waste sludge

Abstract: PURPOSE:To pulverize sludge with high efficincy while suppressing an energy consumption, by mixing a relarively laege amount of quick lime with waste sludge, adding a fixed amount of Mohr's salt to the mixture, and heating and agitating the mixture CONSTITUTION:Waste sludge generated in the treatment of waste water from a sewer system is mixed with 10% by weight or more of calcium oxide Thereafter 5% by weight or more of ammonium ferrous sulfate (so-called Mohr's salt) is added to the mixture The mixture is then heated and agitated According to this treatment, the sludge can be pulverized with high efficiency while saving an energy consumption

Improvements in hydraulic cements

Abstract: Alkaline residues in a hydraulic cement are neutralised by incorporating in the cement an acid material having a dissolution rate sufficiently slow that the setting process is not adversely affected. Typically the neutralising agent comprises an alkali metal/phosphorus pentoxide glass which is incorporated in the cement prior to or after mixing with water. The pH of the glass is adjusted by controlling its phosphorus pentoxide content, and the dissolution rate is determined by including e.g. calcium oxide and/or alumina to the glass composition.