US2001808A - Furnace for producing purified metals - Google Patents

Description

May 21, 1935. M. L. WOOD 2,001,803

FURNACE FOR PRODUCING PURIFIED METALS Filed Aug. 28, 1933' 3 Sheets-Sheet l v Affornega 3 Sheets-Sheet 2 M. L. WOOD Filed Aug. 28, 195-3 May 21, 1935.

FURNACE FOR PRODUCING PURIFIED METALS /m en+0r Naur/ce L, Wood 0 M,M*M4

Affarnegs May 21, 1935. M. L. WOOD FURNACE FOR PRODUCING FURIFIED METALS Filed Aug. 28, 1953 3 Sheets-Sheet 5 ,4 Howey;

Patented May 21, 1935 UNITED STATES PATENT OFFICE 2,001,808 FURNACE FOR PRODUCING PUBIFIED METALS bury, Conn., a corpo Application August 28, 1933, Serial No. 687,023

2 Claims. (CI. 13-29) This invention relates to improvements in producing purified metals, and more particularly, metals such as copper, copper alloys and the like.

Heretofore in the production of copper and copper alloys, the finished product frequently contained considerable amounts of non-metallic inclusions, oxides, etc. In particular, alloys containing appreciable amounts of aluminum or silicon or nickel are prone to give rise to these impurities. Needless to say, these inclusions are very detrimental to the casting and to products fabricated therefrom.

It has been common in the art to cover the surface of the molten metal with a layer of charcoal. While this layer of charcoal prevents excessive oxidation, it is not particularly effective in cleansing the metal of oxide particles already present. Furthermore, when such molten metals covered with charcoal are poured in the ordinary manner from the top, even with the greatest care to hold back the surface dross,

since the metal is poured from the top, these inclusions become mechanically tangled in the raulting casting. Moreover, the layer of charcoal gives rise to gaseous impurities in the metal, namely, carbon monoxide and carbon dioxide, which are formed from the burning of the charcoal. These gases tend to produce holes and pockets in the cast metal.

30 One object of this invention, therefore, is to provide an improved process for producing purified metals, whereby these non-metallic inclusions, oxides, etc., are substantially eliminated from the metals.

Another object of the invention is to provide an improved process for producing purified metals, whereby gases such as carbon monoxide and carbon dioxide are substantially eliminated there from.

Another object of this invention is to provide an improved apparatus whereby the foregoing improved process can be readily and efficiently carried out.

With the above and other objects in view, this invention includes all. improvements over the prior art which are disclosed in this application.

In the accompanying drawings, in which one way 01% carrying outthe invention is shown for illustrative purposes: 50 Fig. l is a front elevation of an induction furnace made. in accordance with this invention;

Fig. 2 is an elevation, mostly in section, on line 22 of Fig. l; and Fig. 3 is an elevation, mostly line 8-4 of Fig. 2. v i

in section, on

The induction furnace I I has an-outer metal casing I I provided with a lining I2 of electrical insulation. Within said insulation lining I2 is refractory material II. The main chamber ll of the furnace is provided to hold the main body 5 of molten metal Ii. The pouring-spout I8 extends from outside the furnace inwardly and downwardly to communicate with the main chamber II at the location I'I adjacent the bottom of the main chamber. The opposite leg-portions or 10 leg-chambers I8 and I! extend downwardly from the bottom of the main chamber I4 and are directed toward each other at their lower ends so as to be joined together at their lowest locations at to form a complete loop 2|. Thus, when 15 the furnace is charged with metal, the molten metal not only occupies the main chamber H, but extends downwardly to fill the loop 2| formed by the leg-portions II and II.

Extending transversely through the loop por- 20 tion II is an iron core 22 which will ordinarily be formed of laminations in the usual manner. The opposite ends of this core I! are preferably magnetically connected with each other by similar iron laminations 23, 24, 25, etc. Surrounding the 25 core 22 is a coil 26 having a plurality of helical turns of copper ribbon or wire 21, as is usual. The coil 26 ordinarily is supplied with an alternating current of suitable frequency in the well-known way. It, will be evident that the loop II of molten 30 metal forms a complete single turn of the secondary winding of a transformer of which the coil 26 formstheprimarywinding,allasiswell understood by those familiar with the art of induction furnace construction.

Thetopofthesin'faceofthemetal Iliscovered witha layer of molten slag 2|.

In operation, the alternations of the electric current induce'a heavy current intbe loop ii of metal, causing considerable heating of the legportions II, II thereof. Duepartly to this heating action in the leg-portions of metal which extend downwardly, and partly due to the violent stirring action of the electric current, metal surges upwardly with considerable speed and force from the leg-portions I I and I! in the directions indicated by the upwardly-extending arrows (Fig. 3). Thus, molten metal is brought up from the depths of the bath of metal against the under side of the liquid slag layer a, thereby permitting W the slag to come in contact with the non-metallic inclusions and particles of oxide, resulting in these inclusionaoxides, etc., coalescing with or becoming entrapped in the slag layer, thereby resulting in the inclusions and oxides being eliminated from the body of metal and retained by the covering of slag.

This violent stirring action that takes place is continued until the steady purifying action that takes place by the oxides and other non-metallic inclusions contacting with and becoming entrapped in the liquid slag layer, results in the metal becoming substantially free from non-metallic inclusions, oxides, etc. At the same time that this removal of non-metallic inclusions is taking place, the liquid slag layer acts as aperfect blanket to prevent the absorption of gases by the metal, and as the slag itself contains no gases, as is true of charcoal, the metal is thus protected against absorption of gases.

After this purifying action has proceeded sufficiently to substantially remove the various objectionable inclusions, the metal is then poured from the furnace into suitable molds through the pouring-spout l6. Inasmuch as this pouringspout I6 connects with the main chamber 14 only at a location well below the liquid slag layer 28, there is no possibility of entraining or trapping any portion of the slag layer with the metal during pouring, as would occur if pouring-spout l6 were so located as to permit the top surface of the metal and slag to be poured off the metal into the molds. Thus, the finished product has a maximum degree of purity, freedom from inclusions of non-metallic particles, slag, gases, etc.

The invention may be carried out in other specific ways than that herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiment is therefore to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

I. A furnace for producing purified copper, copper alloys or the like comprising: a main chamber for holding a quantity of molten metal; a leg chamber of relatively-small cross-sectional area communicating with the bottom of said main chamber and extending downwardly therefrom; means for heating metal in said leg chamber; and a pouring spout communicating with said main chamber only adjacent the bottom thereof and well away to one side from the vertical planes enclosing said downwardly-extendmg leg-chamber.

2. A furnace for producing purified copper, copper alloys or the like comprising: a main chamber for holding a quantity of molten metal; a loop chamber communicating with the bottom of said main chamber and extending downwardly therefrom; means for heating metal in said loop chamber; and a pouring spout communicating with said main chamber only adjacent the bottom thereof and well away to one side from the vertical planes enclosing said downwardly-extending loop-chamber.

MAURICE L. WOOD.

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