Geological SeriesVirginia Geological Survey, 1909 |
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Andere Ausgaben - Alle anzeigen
Häufige Begriffe und Wortgruppen
Al,O Alumina Alumina Al2O3 Analyses Appalachian argillaceous limestone Augusta county beds blue limestone Blue Ridge calcareous shales Calcium carbonate Calcium carbonate CaCO3 Cambrian cement material cement rock cent Chambersburg formation chert Chickamauga limestone clay clayey coal Coastal Plain copper crystalline dark deposits division dolomite fault feet fine-grained fossils granite Holston Iron oxide Iron oxide FeO3 J. H. Gibboney Knox dolomite layers Lime CaO limestone limestones and shales Long tons Magnesia Magnesia MgO magnesian limestone Magnesium carbonate Magnesium carbonate MgCO3 manufacture marble Martinsburg shale Massanutten massive MgCO₁ miles mineral mines natural cement occur Ordovician Ordovician limestones outcrop Piedmont portion Portland cement production pure limestone pyrite quarried quartz railroad region sandstone sandy shale schists Sevier shale shale shaly limestone Shenandoah short tons Silica Silica SiO2 slate southwestern Virginia Stones River formation strata Tazewell thickness thin-bedded Total upper Valley vicinity Walker mountain Wise county Wythe county
Beliebte Passagen
Seite 285 - The material used in the manufacture of natural cement is invariably a clayey limestone, carrying from 13 to 35 per cent, of clayey material, of which 10 to 22 per cent, or so is silica, while alumina and iron oxide together may vary from 4 to 16 per cent.
Seite 5 - ... of the clayey materials. The burning takes place at a high temperature, approaching 3,000° F., and must, therefore, be carried on in kilns of special design and lining. During the burning, combination of the lime with silica, alumina, and iron oxide takes place. The product of the burning is a semi-fused mass called clinker, and consisting of silicates, aluminates, and ferrites of lime in certain definite proportions.
Seite 19 - Drying the raw materials. — With the exception of the marls and clays used in the wet method of manufacture, Portland cement materials are usually dried before the grinding is commenced. This is necessary because the raw materials, as they come from the quarry, pit or mine, will almost invariably carry appreciable, though often very small, percentages of water, which greatly reduces the efficiency of most modern types of grinding mills, and tends to clog the discharge screens.
Seite 7 - ... theoretically available are, however, reduced to a very few in practice under existing commercial conditions. The necessity for making the mixture as cheaply as possible rules out of consideration a large number of materials which would be considered available if chemical composition was the only thing to be taken into account. Some materials otherwise suitable are too scarce; some are too difficult to pulverize. In consequence, a comparatively few combinations of raw materials are actually used...
Seite 25 - Natural cements, after burning and grinding, are usually yellow to brown in color and light in weight...
Seite 7 - States were probably deep-sea deposits formed in this way. Some of these limestones still show the fossils of which they were formed, but in others all trace of organic origin has been destroyed by the fine grinding to which the shells and corals were subjected before their deposition at the sea bottom.
Seite 4 - CEMENT. Portland cement is produced by burning a finely ground artificial mixture containing essentially lime, silica^ alumina, and iron oxide, in certain definite proportions. Usually this combination is made by mixing limestone or marl with clay or shale, in which case about three times as much of the lime carbonate should be present in the mixture as of the clayey materials.
Seite 20 - NJ, the reduction is accomplished in a series of rolls. The majority of plants use either the Griffin mill and tube mill or the ball and tube mills, and there is probably little difference in the coat of operating these two combinations.
Seite 4 - After grinding, if the resulting powder (natural cement) be mixed with water it will harden rapidly. This hardening or setting will also take place under water. Natural cements differ from ordinary limes in two notable ways — (1) the burned mass does not slack on the addition of water; (2) the powder has hydraulic properties ; that is, if properly prepared it will set under water.
Seite 13 - ... much harder than argillaceous limestones like the Lehigh district "cement rock," and it was very difficult to pulverize them finely and cheaply with the crushing appliances in use when the Portland cement industry was first started in America. A series of analyses of representative pure hard . limestones, together with analyses of the clays or shales with which they are mixed, is given in the following table: Analyses of pure hard limestones and clayey materials.