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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y .
A COLORIMETRIC METHOD FOR THE DETERMINATION OF CARBON IN IRON AND STEEL. B y JEROYE F. KOHOUT. Received Jaiiuary 29, 1912.
This method is similar t o the one proposed by Eggertz and may be used with Stead's modification. This method was worked out and used by the writer while engaged in iron and steel analysis, and is very useful in controlling the work of an open-hearth or similar furnace. It eliminates all necessity for calculation and gives direct readings which are accurate within the limits of colorimetric work. The method consists in dissolving the sample and a standard iron or steel in dilute nitric acid (1-3) and comparing the colors. The essential difference lies in the method of dilution. In the old and ordinarily used way the sample is diluted t o a definite volume, and the standard is then diluted until the color of both the solutions is the same. The carbon content of the sample is calculated f;om the ratio of the volumes of the two solutions. I n the proposed method the standard is diluted t o a definite volume depending on its carbon content, thus a standard of 0.5 yo carbon is diluted t o 5 cc., one of 0.65% to 6 . 5 cc., etc. The sample is diluted until the colors match. The volume of the sample gives its carbon content directly without any calculation. Thus if the sample contained 6 . 8 cc. and matched a standard 6 cc. in
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volume, the carbon content of the sample was 0 . 6 8 per cent. C. I t is always best t o use a standard of about the same percentage of carbon as that of tlie sample so that the height of the two solutions will be about the same. The writer used tubes 7 mm. in diameter and graduated t o 0.05 cc.; this gave greater height to the solution and allowed the volume to be read very closely. The weight of standard and sample taken was 0.I gram each. I n the following table the volumes given for the samples are the mean of several determinations run with each standard. I n every case the colors matched when the sample was diluted to within 0 .I cc. of the amount given in the third column.
. --Standard.
Carbon det. by direct combustiou in oxygen. Per cent. 0.06 0.11 0.56 0 72 0 89 1 .05
Sample.
Volunie. cc. 6.0 11.0 5.6 7.2 8.9 10.5
Volume. cc. 5.5 13.4 5.8 7.6 8.4 10.1
Carbon. Per cent. 0.055 0.134 0.58 0.76 0 84
I .01
Carbon det. by direct combustion in oxygen. Per cent. 0.057 0.137 0.58 0.77 0.86 1.02
The results are very slightly lower than those obtained by direct combustion, but are close enough €or routine commercial work and furnace control.
LABORATORY AND PLANT
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the kilns and to keep moving various minor operations of the process. B y RICHARD K . MEADE The size of the power plant which will be required Received February 24, 1912 in manufacturing 3,000barrels of cement per day will I n the manufacture of Portland cement, the ques- depend largely upon the class of material to be ground, tion of power enters in quite largely. In the manu- upon the type of machinery used to do this, and the facture of 3,000 barrels of cement per day, there must degree to which it is done, as well as the proper inbe ground approximately 1,650 tons of material to stallation of the plant itself and the means of transan almost impalpable powder every twenty-four mitting the power to the machinery. hours. Nine hundred tons of this represent the raw The general character of the power generators material which must be reduced from pieces of stone themselves and the arrangement of the engine and as large as a man can handle to such a degree of fineboiler rooms is similar to that of other manufacturing ness that from 90 t o 98 per cent. of the powder will pass a Ioo-mesh test sieve. Six hundred tons r e p > - enterprises where much slow-moving, heavy machinery sent the slag-like clinker which must be pulverized I S operated. Cross compound condensinq engines of the Corliss type are generally employed, although so fine that zt least 92 per cent. of it will pass this in electrically driven mills the steam turbine has been sieve, while the remaining one hundred and fifty tons used successfplly: when natural gas is available, gas consists of the coal for heating the kilns, which is pulengines are often employed. verized to about the foregoing degree of fineness. The steam plant usually consists of water tube The power required to run this amount of machinery is probably greater than that which would be utilized })oilers. These are generally of the horizontal type, in the manufacture of a similar value of any other but, occasionally, vertical boilers are employed. At one or two mills the boilers are arranged to utilize commodity. I n addition t o running the machinery necessary the waste gases from the kilns in making steam, but for grinding, power is required in quarrying and trans- this instdllation has never proved very satisfactory. The transmission of power can be effected b y either porting to the mill the raw materials, in operating the elevators and conveyors used to handle the product shaft or electrical drives, but, in either event, the disin the various stages of its manufacture, to revolve tribution of the power to the mills must be effected with the least possible loss due to friction. When the I Read at the meeting of the American Institute of Chemical Engitransmission is non-electrical, short, powerful shafts neers at Washington, December. 1911 THE DISTRIBUTION OF POWER IN PORTLAND CEMENT MANUFACTURE.
