Showing papers on "Calcium oxide published in 1973"

Voltage-nonlinear resistors

Abstract: The invention relates to voltage-nonlinear resistors having nonohmic resistance due to the bulk thereof and more particularly to varistors, which utility as surge absorbers and D.C. stabilizers, comprising zinc oxide, bisumuth oxide, cobalt oxide, boron trioxide and at least one member selected from the group consisting of magnesium oxide, calcium oxide, barium oxide and strontium oxide.

Exo-thermic heat transfer

Abstract: A composition for producing heat when contacted by water at a relatively uniform temperature up to about 260* F without appreciable generation of steam consisting essentially of a particulate primer material which is exothermic when contacted by water, a particulate inorganic oxide or salt which is highly exothermic when contacted by water, and a film-forming component which encapsulates the primer and inorganic oxide or salt in the dry state. A preferred primer is anhydrous calcium chloride, a preferred inorganic oxide is calcium oxide, and a preferred filmforming component is a combination of positively charged guar gum and anhydrous sodium tetraborate. A method and apparatus especially adapted for use of the composition are disclosed, in the heating of a packaged food product.

Method and apparatus for treating sumps

Abstract: Lime, preferably as calcium oxide, is mixed with the contents of sumps, such as oil well sumps, and these generally have a pasty or plastic consistency. The calcium oxide reacts with the materials present and also dehydrates the contents of the sump, causing the sump contents to stiffen. This mixing is performed by a drag line scoop that carries calcium oxide through the sump contents, mixing and blending the oxide and contents as it moves because of the unique construction of the mixing scoop. Once the mixing and blending is complete and reaction of the calcium oxide and the contents is complete, the sump contents are dredged and deposited on high ground to dry by the combined action of sun and air. Drying periods may range from several days to several weeks and the material thereupon becomes a dry, hard and stable type of soil suitable for fill purposes and which, when neutralized with acid, also may be suitable for agricultural purposes.

Processing titaniferous iron ores for the recovery of aluminium, chromium, iron, titanium and vanadium

Abstract: An improved process is provided for to separate iron from titaniferous iron ores by roasting the latter in the presence of a roasting agent made up of a mixture of sodium oxide producing compound and calcium or magnesium oxides or a calcium oxide or magnesium oxide producing compound whereby chromium, vanadium and aluminum oxides can be readily leached out from the ore.

Reduction of nickel oxide

Abstract: A moving bed of nickel oxide containing volatile impurities and having a controlled sulfur content and at least one additive selected from the group consisting of magnesia, calcium oxide or compounds heat decomposable thereto in an amount sufficient to react with the nickel oxide during reduction to provide an antiagglomerating coating on a substantial portion of the nickel oxide granules is established and is contacted with a reducing gas at temperatures high enough to reduce the nickel oxide and to refine it. The addition agent is advantageously added to the nickel oxide as an aqueous solution of a water soluble compound of magnesium or calcium, e.g., magnesium sulfate or chloride or nitrate. The process is advantageously used in conjunction with high temperature roasting of nickel sulfide, with roasting possibly followed by chlorination to control the copper content, to provide a combination of high temperature treatments that is effective in providing a refined metal product.

Process for the production of synthetic wollastonite and diopside

Abstract: Synthetic wollastonite is produced by sintering a mixture of silica and calcium oxide, and synthetic diopside or a mixture thereof with synthetic wollastonite is produced by sintering a mixture of silica, calcium oxide and up to an equimolar proportion, based on the calcium oxide, of magnesium oxide. When the CaO:MgO mole ratio is 1:1, synthetic diopside is produced. In all cases, silica is used in an amount of from 4 to 15%, and preferably from 5 to 10% in excess of the stoichiometric amount necessary to obtain the desired product.

Method for the production of fiber-reinforced resin compounds

Abstract: A method for the production of a fiber-reinforced resin compound. The method comprises spraying onto a suitable substrate from three respectively different nozzles: 1. an unsaturated polyester resin composition having a viscosity of about 3000 to 15000 Cps at 25°C; 2. a fiber-reinforcing material and 3. a thickening agent of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide or beryllium oxide suspended in a liquid polyester resin or a mixture of a liquid polyester resin and styrene, the weight of (1):(2):(3) being 100:20-55:3-30. The individual streams of (1), (2) and (3) intersect one another after exiting from said nozzles and prior to contacting said substrate to form one stream. The method can give a fiber reinforced resin compound having a strength equivalent to or more that of (sheet molding compound) and is simple in operation and can be carried out at a cost equivalent to or less than that bulk molding compound.

Lime reactivity of tropical and subtropical soils

Abstract: Research to deermine the factors that significantly influence lime pozzolanic reactions in soils has been fairly well restricted to soils of temperate regions. Extrapolation of these data to tropical soils was not justified without additional investigation. Selection and sampling of tropical and subtropical soils in this study were accomplished so that representative cross sections of soil characteristics were provided. The laboratory investigations included the use of standard techniques to determine physical, chemical, and mineralogical properties of the 26 soils. Development of lime pozzolanic reactions was measured by maximum incrasese in the unconfined compressive strength of the lime-treated soils after various curing periods. It was concluded that soil pH, cation exchange capacity, base saturation, silica sesquioxide ratio, silica-alumina ratio, and pedo-logic order influence the development of lime pozzolanic reactions in Ultisols and Oxisols. Strength increases after 28 days of curing at 73 F varied from 22 to 606 psi. Different indexes of lime reactivity and weathering were found to be valid within the Ultisols (soil pH) and within the Oxisols (silica sesquioxide ratio).

Lime slurry pressure injection tames expansive clays

Abstract: Shrinking or swelling soils under foundations inflict at least 2.3 billion dollars per year in damages to houses, buildings, roads, and pipelines. This article presents a promising and relatively inexpensive solution to many to these unstable soil problems -- lime slurry pressure injection (LSPI). A lime slurry is pumped into the soil under pressure, forming a network of interconnecting, sheet- like seams. These seams act as moisture barriers, preventing the movement of moisture either into or out of the soil. Since the soil's moisture content is now constant, moisture- induced swelling or shrinkage of soils is eliminated. For the past five years, LSPI has been used extensively throughout the North Texas area and other states. LSPI is used with a slab-on-grade foundation, where structural solutions to expansive clay soils are not feasible. /AUTHOR/

Transparent articles of aluminium oxide and method of manufacturing said articles

Abstract: 1. IN A FORMED ARTICLE CONSISTING OF MAGNESIUM OXIDECONTAINING AND ANOTHER METAL OXIDE-CONTAINING TRANSPARENT DENSELY SINTERED POLYCRYSTALLINE ALUMINUM OXIDE, THE IMPROVEMENT COMPRISING THAT THE OTHER METAL OXIDE IS CALCIUM OXIDE AND THAT THE CONTENT OF CALCIUM OXIDE IS 0.001-0.02% BY WEIGHT.

Method of preparing a calcium carbonate-magnesium hydroxide pigment

Abstract: The present invention relates to an improvement in the method of preparing a magnesium hydroxide-calcium carbonate product which is useful, for example, as a paper pigment. A process for preparing such product involves slaking dolime to convert the calcium oxide and magnesium oxide to their respective hydroxides and then carbonating the calcium hydroxide portion to calcium carbonate. The present improvement comprises employing a slaking solution which contains a water soluble boron compound. The improved process results in a magnesium hydroxide-calcium carbonate product with enhanced optical properties.

Process for treatment of vanadium containing fly ash

Abstract: The invention is addressed to the recovery of vanadium by the treatment of fly ash derived from bituminous or petroleum products, such as bituminous schists. In accordance with the practice of this invention, the fly ash is treated with a concentrated caustic soda solution selectively to solubilize vanadium, and in adding calcium oxide to the reacting solution in an amount within the range of 6-40 percent of the silica contained in the ash, with the addition being made preferably during the latter portion of the treatment.

Consolidation of high ash papermill sludges

Abstract: EXPERIMENTAL LABORATORY RESULTS FOR ONE-DIMENSIONAL COMPRESSION BEHAVIOR OF DEWATERED PULP AND PAPERMILL SLUDGES ARE PRESENTED. DATA WERE OBTAINED WITH A FIXED-RING OEDOMETER AND A PRESSURIZED CONSOLIDATION CELL ON A SECONDARY FIBER MILL SLUDGE IN THE NATURAL STATE, AT DIFFERENT ORGANIC CONTENTS, AND WITH LIME OR FLYASH ADMIXTURES. CONCLUSIONS INCLUDE: COMPRESSION INDEX REMAINED CONSTANT FOR LOAD INCREMENT RATIOS OF 1.0 TO 0.25, SHOWED A LINEAR DECREASE WITH INCREASE IN INITIAL SOLIDS CONTENT BY WEIGHT, AND HAD A LINEAR RELATIONSHIP WITH ORGANIC CONTENT FOR COMPARISONS AT THE SAME SOLIDS CONTENT BY VOLUME; FOR SMALL LOAD INCREMENTS MEASURED PORE PRESSURES DISSIPATED MORE RAPIDLY THANPREDICTED BY THEORY; THE RATE OF SECONDARY COMPRESSION PER UNIT PRESSURE INCREASED WITH DECREASE IN LOAD INCREMENT RATIO; LIME OR FLYASH ADMIXTURES INCREASED THE COEFFICIENT OF CONSOLIDATION; TEMPERATURE INCREASE REDUCED THE EQUILIBRIUM VOID RATIO, ALTERED THE COEFFICIENT OF CONSOLIDATION, AND INCREASED SECONDARY COMPRESSION RATES. /AUTHOR/

Acceleration of lime-clay reactions with salt

Abstract: THE EFFECT OF POTASSIUM IODIDE ON AN EXPANSIVE CLAYEY SOIL TREATED WITH LIME AND CEMENT HAS BEEN INVESTIGATED. ON THE BASIS OF EXPERIENCE REGARDING THE UTILITY OF THE DIFFERENTIAL THERMAL ANALYSIS (DTA) TECHNIQUE IN A SIMILAR SITUATION, THE INTERPRETATIONS OF THE PAPER ON "ACCELERATION OF LIME-CLAY REACTIONS WITH SOIL", IS DISCUSSED. THE IDENTIFICATION OF CLAY MINERALS ON THE BASIS OF DTA CURVES COULD BE AN ERROR. THE STATEMENT IS ILLUSTRATED BY CONSIDERATION OF THE DTA CHARACTERISTICS OF MONTMORILLONITE. IT IS NECESSARY TO SUPPLEMENT THE DTA DATA WITH X-RAY DIFFRACTION CHARACTERISTICS, BASE EXCHANGE CAPACITIES, SWELLING CHARACTERISTICS, CHEMICAL ANALYSES ETC., IF CONCLUSIVE IDENTIFICATION IS TO BE MADE. THE DTA OF SOIL, LIME, AND 1% SODIUM CHLORIDE WITHOUT ADDITION OF ANY MOISTURE, IF OBTAINED, WOULD HELP IN SEPARATING THE EFFECTS OF THE MERE PRESENCE OF LIME AND SODIUM CHLORIDE FROM THE EFFECT OF THE REACTION OF THESE WITH SOIL-LIME-SODIUM CHLORIDE-WATER MIXTURE. IT IS POINTED OUT THAT A NEW PEAK ON THE DTA CURVE DOES NOT MEAN THAT THE NEW MATERIAL IS CRYSTALLINE. NO DATA WAS FOUND TO SUPPORT THE SUGGESTION THAT THE ROLE OF SODIUM CHLORIDE IS A CATALYST. ADVANTAGES IN THE USE OF POTASSIUM IODIDE AS A TRACE ADDITIVE WITH A MIXTURE OF LIME AND CLAY CONTAINING MAJOR AMOUNTS OF BEIDELLITE AND NOUTRONITE IS POINTED OUT.

Stabilized burnt lime product and process

Abstract: A stabilized burnt lime product for use in the reduction of ores in blast furnaces consists of a large proportion of free burnt lime bound together by iron oxide and other oxides to form a solid material which is slow to react with moisture or carbon dioxide in the atmosphere. The product is obtained by a sintering process in which crushed limestone is burnt to form burnt lime and this is impregnated with a fluid mixture of mixed oxides, mainly iron oxide and calcium oxide. The iron oxide is obtained by feeding with the crushed limestone to the sintering process finely divided substances containing iron.

An evaluation of the adsorptive properties of fly ash with reference to a pulp and paper mill water effluent

Abstract: The results of the research indicated first that the fly ashes in general did not have conventional adsorptive properties comparable to a commercial-grade activated carbon. Softwood-bark-derived fly ash did, however, absorb iodine and phenol better than the hardwood-bark-derived fly ashes. The study also indicated that the ability of a fly ash to be used effectively in the treatment of a particular pulp and paper mill waste was proportional to its lime (CaO) content. Those fly ashes whose origin was hardwood bark had high lime contents and were most effective in removing caustic bleaching extract color, chemical oxygen demand, and 5-day biological oxygen demand. Effective treatment was arbitrarily defined as a color reduction of 90 percent or greater. /Author/

Magnesia-base sintered article and process for producing the same

Abstract: Finely divided magnesia or a substantially homogeneous mixture of finely divided magnesia with calcium oxide is blended with finely divided magnesium hydroxide or a mixture of both magnesium hydroxide and calcium hydroxide, and the resultant mixture is formed into a briquette. The thus prepared briquette is calcined to sinter same, thereby to produce a novel porous article having pores dispersed uniformly therein and having a low bulk density, high physical strength and excellent resistance to thermal shock. The approximate porosity value of the novel article can be predetermined by selection of the particle sizes and the blending ratios of the raw materials employed.

Metal-to-glass joint

Abstract: The invention relates to glass industry. A glass containing silicon dioxide, aluminum oxide, zirconium dioxide, strontium oxide, sodium oxide, potassium oxide, tungsten trioxide, lanthanum oxide and calcium oxide is thermally sealed together with gold.

Lime stabilization of frost-susceptible soils

Abstract: Depending on (1) nature and composition of the soil, (2) curing (time-temperature), (3) lime type, (4) lime percentage, and (5) density of compacted mixture, lime-treated soils display a wide range of engineering properties. Extensive studies have shown that all fine-grained soils react with lime to effect beneficial changes in workability, plasticity and swell properties. The extent to which the lime-soil poxxolanic reaction proceeds is influenced primarily by natural soil properties. The difference between the compressive strengths of the natural and lime-treated soil is an indication of the extent to which the lime-soil pozzolanic reaction has proceeded. Substantial strength increase indicates that the soil is reactive with lime and can probably be stabilized to produce a quality paving material (base or subbase). The validity of using initial unconfined compressive strength ()-cycles) as a measure of freeze-thaw resistance was demonstrated in extensive studies. Recent studies of different types of cementitious stabilized materials (lime-soil, soil-cement, lime-flyash) have confirmed that initial mixture compressive strength can be used to predict the cyclic freeze-thaw resistance of a stabilized soil. Factors influencing strength development, influence cyclic freeze-thaw resistance in the same fashion. Studies show that cured lime-soil mixtures with good freeze-thaw resistance can be developed when reactive soils are stabilized with quality lime. The strength required to prevent excessive heaving of cured lime-soil mixtures, approximately 200 psi, compares favorably with the strength required to restrict the heave of cement stabilized materials. Adequate mixture design, construction, and quality control procedures must be utilized to insure the successful utilization of lime stabilized soils in pavement construction.

Stoichiometric relationship between calcium oxide and sugars in water solution

Abstract: The interaction between 5 sugars and CaO in water solution has been found to be equimolar. Calcium uptake and ultraviolet absorption patterns between reducing and non-reducing sugars in basic solution indicate that cation- and/or anion-dependent reactions occur simultaneously and independently. It is suggested that variability of reported stoichiometric ratios between sugars and alkali or alkali-earth metals may also be a function of the polarisability of sugarderived reacting species, under a given set of experimental conditions.

Stabilisation of alluvial soil with lime and fly ash

Abstract: The paper reports the results of laboratory investigations and field research on the stabilization of alluvial soil with lime and fly ash and the use of such stabilized soil as base or subbase in the lower layers of the pavement system for both roads and airfields. The investigation using fly ashes from three thermal power stations of Delhi, Kanpur and Faridabad showed that alluvial soils could be staisfactorily stabilized with 15 percent of lime and fly ash in the proportion of 1:4. These proportions enabled an increase in the CBR value from 8-14 to 52-110 without any additive. With the addition of 1 percent gypsum by weight of soil, lime and fly ash, the CBR value increased to 73-190. Improvement was also noticed in the unconfined compressive strength of the lime-fly ash stabilized soil when 1 percent gypsum was added. Higher concentration of lime improved neither the CBR value nor the compressive strength of the stabilized soil. Other additives such as sodium carbonate (0.1 percent) and calcium chloride (0.25 percent) improved the CBR value of the stabilized soil significantly but the compressive strength only marginally. The results show that lime-fly ash stabilized soil base/subbase course would be about 50 percent cheaper than conventional stone soling or granular layer with oversized stone metal, which it can replace, in areas, where fly ash is locally available and good quality stones are either costly or have to be transported from a long distance. /Author/

Lime-Cement Combination Stabilization

Abstract: : Soil stabilization is used extensively in road and airfield construction. In particular, soil-cement appears to be a favorite among the engineers. As the plasticity of a soil increases, the ability to adequately mix the cement with the soil becomes a critical factor. Also the quantity of cement required to stabilize the soil becomes excessive. The objective of the study was to determine the effect of reduced compacted density on the durability of cement stabilized clays, pretreated with lime. The reduction in density did not impair the durability of cement stabilized clay soils, which were pretreated with lime. Most of the test results indicated an improved resistance to freeze- thaw. An evaluation of the unconfined compressive strength results obtained during freeze-thaw shows that lime pretreatment improved the strengths.

Device for the study of single crystals thermoluminescence. Application to the emission of calcium oxide.

Abstract: The authors describe a device made for the study of single crystals thermoluminescence and allowing an uniforme heating of samples with a rather large size The mounting is applied to the emission of the F and F+ centres of calcium oxide