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which is part of the dividing line between arcas B and C. This structure is almost like the structure of malleable iron in its appearance under the microscope, but scattered through it can occasionally be seen flakes of graphite.

The center of the bar C, Fig. 6, has the structure of unchanged gray iron. This is shown in the lower section of Fig. 8.

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FIG. 8-STRUCTURE OF B AND C, FIG. 6, IS SHOWN AREA HAS THE

CHARACTERISTIC OF GRAY IRON

W. E. Ruder of the research laboratory of the General Electric Co., Schenectady, N. Y., who made the micrographs for this paper, said in regard to the changed structure of the gray-iron bar: "The only explanation which I can give for the peculiar structure shown is that the entire material

up to the dividing line between A and B, Fig. 6, was in a semimolten condition, and while in this condition the copper oxide became mixed with it and the oxygen was given up by the copper and united with the graphite. The changing of graphitized carbon to temper carbon in section B is very unusual and until this experiment I did not think that this change could be brought about short of actual fusion."

Discussion

In

THE CHAIRMAN, MR. W. R. BEAN.-It seems to me that what Mr. Diller has found may possibly bear some relation to some of the problems involved in the hot galvanizing of malleable castings. We have been conducting experiments for a considerable period of time on that question, which is vital to a great many producers and users of malleable iron. making very careful tests we have been unable to duplicate the change in quality which results in hot galvanizing malleable iron by quenching, heating and quenching identical specimens for the same temperature. Thus it appears that the change is not one which comes directly or is closely associated with the actual quenching of the part, but that there is some action of the zinc on the metal itself, whether in penetration or in what way it may be. I do not know that it is so; we have not been able to prove it one way or the other.

The Application of Powdered Coal to Malleable Annealing Furnaces

BY CHARLES LONGENECKER, Pittsburgh.

The conservation of fuel is one of the most timely subjects confronting our manufacturers today. Its significance is just beginning to be appreciated. It is a national problem and it is therefore incumbent upon all of us to further the more economical disposition of our fuels. While the underlying motive is the preservation of our resources, fuel conservation will at the same time promote the personal interests of every manufacturer. It is apparent that any reduction in our fuel expenditure has a direct bearing on the cost sheet.

In the malleable iron foundry there are two processes which require for their fulfillment the generation of a large quantity of heat. These are the melting of the pig iron and scrap and the annealing of the castings. The furnace efficiency in both cases is low, and there is thus afforded an opportunity to effect a very considerable reduction in the fuel consumption. This has been accomplished in annealing furnaces using powdered coal as fuel. It is the object of this paper to present some facts dealing with this subject.

Early Installations

There are today some 15 to 20 malleable foundries burning powdered coal in annealing furnaces with satisfactory results.

This fuel was first applied at the plant of the Erie Malleable Co., Erie, Pa. The credit for the success of this installation belongs to B. J. Walker, who in 1896 operated annealing furnaces in which the source of heat was powdered coal. Other companies who appreciated the worth of this fuel and whose installations closely followed that of the Erie Malleable Co. were the International Harvester Co. and the Symington company. A recent installation which it

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FIG. 1-LONGITUDINAL SECTION ON 4-4, FIG. 2, THROUGH ANNEALING FURNACE

is the intention of this paper to describe, is that at the Pressed Steel Car Co., formerly the Pennsylvania Malleable Co.

This company made its initial application of powdered coal to annealing furnaces in the fall of 1917, and since then these furnaces have been in continuous operation. In this plant the furnace is practically all below floor level with the roof formed by bungs.

There are 10 large and 18 small furnaces, some of which are used for annealing steel castings. The larger ones have a capacity of 50 tons, while the smaller hold 25

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tons. Fig. 1 shows a longitudinal cross section of the large furnace and Fig. 2 a transverse section.

As is well known, the requisites in an annealing furnace from a thermal standpoint are a uniform temperature (and) consequently heat) throughout the heating chamber and the maintenance of a constant degree of heat for the proper length of time. To secure these conditions, it was necessary to install four burners in each furnace and maintain a steady flow of coal to these burners. The following table shows a typical run and illustrates how well the conditions demanded have been met:

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From the foregoing we obtain the following summary:
Furnace lighted, July 10, noon.

Time to bring furnace to temperature 1600 degrees, 18 hours.
Furnace held at temperature, 1600 degrees, 120 hours.

Firing discontinued, 6 a. m., July 16.

Bungs (roof) removed, 6 a. m., July 18. The castings were then removed as soon enough to handle.

as they were cool

A pyrometer is inserted in each end of each furnace. Each one is connected to a central recording instrument. It is the duty of the furnace attendant to read the temperature of each furnace at frequent intervals on this instrument, so that there is little chance for any wide fluctuation in temperature. One attendant supervises all the furnaces.

Time Saved by Powdered Fuel

With powdered coal it requires from 14 to 18 hours to bring the furnace to 1600 degrees, with fuel oil the time is

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