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HE success attending the adapta- application providing the conditions
tion of the electric arc furnace to are favorable. It is therefore evithe steel industry attracted the ser- dent that each particular alloy and ious attention of those most interested means for melting it most efficiently in the problem of melting non-ferreous must receive special attention from alloys. No radical improvements had a metallurgical as well as an electrical been introduced in the art of melting engineering viewpoint or an expensuch alloys for decades and the ap- sive choice is likely to be made. plication of electricity was retarded Many of the mistakes due to failure largely because of failure to fully ap- to recognize these elements are now preciate the benefits derived from its happily past experiences or soon will use as well as the economic factors be. which have served as a deterrent. The war changed many of these fac
FACTORS INFLUENCING USE OF tors and called for conservation of
ELECTRICITY FOR BRASS MELTING natural resources.
An incentive was Among the factors that contributed thereby established for a considera
to the recent intensive development tion of more efficient means of utiliz
of non-ferreous metal melting furning electrical energy.
aces are: Experiment and practise soon proved that a satisfactory heating medium
(A) Reduction of metal loss must be free from the metal bath
(B) Elimination of crucibles itself and the heat must be uniformly
(C) Accuracy of temperature condistributed at such intensity as to
trol prevent hot spots with inevitable and
(D) Rate of production wasteful volatilization of the constit
(E) Quality of product. uent metals which have low boiling
(F) Reduced labor costs and impoints. With these factors estab- proved working conditions. lished as fundamentals much pro- (A) One of the chief difficulties in gress was made in the design of equip- the melting of alloys is the metal loss ment likely to approximate ideal con- sustained due to the volatilization of ditions. There are now some five or constituent metals, particularly zinc. six types in practical use giving rea- The absorption of deleterious gases sonably satisfactory results. Opin- and elements, such as oxygen and ion in this respect is not unanimous sulphur constitute another factor. A as might be expected but it may safely closed chamber free from contamibe said that each type has a field of nating influences enables the metal losses to be considerably reduced and price high. Often they become in order to appreciate the value of broken during the process of heating metal saving, the statistics in relation with the result that the metal must be to this point taken from the report of reclaimed from the fuel bed. Such the Bureau of Mines for 1914 will mishaps contribute to the cost of proserve to show the magnitude of the duction and also materially diminish annual loss in this country. Value of the output. the non-ferreous metals melted $120,- (C) Much of the success in melting 000,000. Metal lost beyond recovery depends upon the accurate control of 272% or $3,000,000. Employment temperature. Pyrometers have been
Fig. 1. Detroit Electric Furnace Co.-Rocking Arc Furnace. One ton furnace at left used for melt
ing manganese bronze. One-half ton furnace at right used for melting red brass alloys. of suitable electric furnaces would re- used to determine the pouring temduce this loss to one per cent. or lower. perature but with the use of crucibles This brief descri ption of the character a great deal of reliance is placed in the of brass melting indicates the import- skill of the operator to determine the ance of being able to reduce metal proper temperature by sight. Conlosses from an economic as well as siderable skill has been developed quality of product viewpoint.
along this line but its actual value has (B) Crucibles have been used since been much overestimated. However, the inception of the art. Since the during the heat the metal may be subwar, however, the quality of crucibles jected to exceedingly high temperahas been extremely poor and the tures which are bound to increase the metal losses as well as to increase the zinc fumes particularly, is practically avidity of the metals for gas absorp- eliminated when electric furnaces are tion.
used. Intense heat to which the (D) With the use of coal or coke operator is subjected in the use of fuel atmospheric conditions affect the fired furnaces is eliminated except in length of time required to melt a pouring the metal. given amount of metal. In the elec- Now that the chief advantages of tric furnace conditions may be du- the application of electricity to brass plicated from day to day and thereby melting have been briefly set forth let production increased. Another aid us consider some of the data collected to increased production is “forcing” to show the efficiency of various fuels
Two furnaces for melting
the furnace which reduces the time used for melting. The data given for melting a given weight of metal below is taken from the Nov. Ist without increased losses or decreased issue of the “Gas Age” for 1919 and quality.
was presented in a report to the Amer(E) Tests show conclusively that ican Gas Association by Thomson the physical properties of alloys are King. much superior when produced in an electric furnace than when melted in
Heat Absorbed in 100 lbs. Brass Melted any other commercial way.
Sensible Heat... .18,800 B.T.U. (F) Conditions for working are
7,000 B.T.U. much improved and the much dreaded disease known as "shakes" due to