Iowa Geological Survey, Volume 15

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Published for the Iowa Geological Survey, 1905 - Geology
 

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Page 52 - By a Portland cement is meant the product obtained from the heating or calcining up to incipient fusion of intimate mixtures, either natural or artificial, of argillaceous with calcareous substances, the calcined product to contain at least 1.7 times as much of lime, by weight, as of the materials which give the lime its hydraulic properties, and to be finely pulverized after said calcination, and thereafter additions or substitutions for the purpose only of regulating certain properties of technical...
Page 50 - 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 semifused mass called "clinker," which consists of silicates, aluminates, and ferrites of lime in certain fairly definite proportions.
Page 58 - Hocks of this series may therefore vary in composition from pure calcite limestone at one end of the series to pure magnesite at the other. The term limestone has, however, been restricted in general use to that part of the series lying in composition between calcite and dolomite, while all those more uncommon phases carrying more magnesium carbonate than the 45.65 per cent are usually described simply as impure magnesites.
Page 57 - Deposition from solution by purely chemical means has undoubtedly given rise to numerous limestone deposits. When this deposition took place in caverns or in the open air it gave rise to onyx deposits and to the "'travertine marls" of certain localities in Ohio and elsewhere.
Page 55 - ... a mixture of correct composition. The almost infinite number of raw materials which are 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....
Page 80 - The dryer above described is the simplest and is most commonly used. For handling the small percentages of water contained in most cement materials it is very efficient, but for dealing with high percentages of water, such as are encountered when marl is to be used in a dry process, it seems probable that double-heating dryers will be found more economical.
Page 98 - Portland cement clinker is much hardier to grind than any possible combination of raw materials ; but it must be remembered that for every barrel of cement produced about 600 pounds of raw materials must be pulverized, while only a scant 400 pounds of clinker will be treated, and that the large crushers required for some raw materials can be dispensed with in crushing clinker. With this exception, the raw material side and the clinker side of a dry-process Portland cement plant are usually almost...
Page 76 - Converting this relation into pounds of raw material and of clinker wo find that 600 pounds of dry raw material will make about 400 pounds of clinker. Allowing something for other losses In the process of manufacture, it Is convenient and sufficiently accurate to estimate that 600 pounds of dry raw material will give one barrel of finished cement.
Page 66 - Portland cement materials they are, therefore, almost ideal. One defect, however, which to a small extent counterbalances their obvious advantages is the fact that most of these soft, chalky limestones absorb water quite readily.
Page 94 - BTU, burned with only the air supply demanded by theory, this dissociation will require 2$*/2 pounds of coal per barrel of cement, a fuel consumption of only 6.6 per cent. Losses of heat in practice. — In practice with the rotary kiln, however, there are a number of distinct sources of loss of heat, which result in a fuel consumption immensely greater than the theoretical requirements given above. The more important of these sources of loss are the following : 1. The kiln gases are discharged at...

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