US2264289A - Process and apparatus for casting metal - Google Patents

Description

J. 0. BETTERTON ET-AL 2,264,289

PROCESS AND APPARATUS FOR CASTING METAL 2 Sheets-Sheet 1 Dec. 2, 1941.

Filed Aug. 22, 1939 g] as N Q De@ 9 J. o. BETTERTON ETAL 2,24,29

PROCESS AND APPARATUS FOR CASTING METAL Filed Aug. 22, 1939 2 Sheets-Sheet 2 l NV EN TOR 5 J'Qse 0 Bdizrfan /raaifJ "fa/and and process for its fulfillment.

- in the part of the castin to the molten copper. 1

ppe

a very porous structure.

Patented Dec. 2, 1941 @raoonss AND 2,264,289 I, ArrAnA'rUs roa CASTING METAL Jesse 0. liette'rton) Metuchen, and

Poland, Highland Park, N; J.,ja.ssignors to American smelting and Refining Company, New York, N. Y,., a corporation of New Jersey Application August aaisaa'se ial No. 291,292 2oc1a1m (o1.22--57.2

The present invention relates"to-apparatus and method for continuously casting copper or copper-alloy rods for the manufacture of; wire.

It has long since been proposed to'introduce.

molten metal continuously intoone end-of amold, solidify it therein, and continuously,with- --'.,the metal being cast and c draw the solidified metal from the other end ofv the mold.- Such operation is generally referred to as continuous casting and itan object '0f the invention to provide an improved apparatus In the practical operation of the continuous Now, when copper is subjected to a continuous castingloperation, the gases associated with the copperare liberated from the metal during solidification thereof and there is a .very real danger of thexliberated gases becoming entrapped in auslng the casting to break. I Therefore, in practice, it is necessary to subject the metal to refining operations for the elimination of the gases present therein, this refining being heretofore carried out in accordance with the usual refining operations, that is to say the casting of copper, so that the process will be oi a truly continuous character, it has been found by experience that certain definite factors and conditions must be observed. These factors and conditions include the following: I

1. The metal (copper or, copper alloys) be properly, prepared preliminaryto its continuous casting; that'is, the metal must be rendered substantially free from oxygen gas-free.

2. There must be used a proper moldmaterial g'mold'that is subjected must 2n I ,and commercially.

3. There must be sufficientcooling of theimold and molten copper therein for eflecting a rapidsolidification of the copper in the mold inasmuch as the more rapid the solidification, the higher ith continuous prowill be the casting speed w duction of sound rod. I

4. The depth of the molten copper above the mold must be'limited in proper manner for avoiding excessive depth thereof with resulting hydrostatic pressure upon the copper in the mold.-

copper is first blown with air until thehydrogen and sulphur hasbeen expelled as completely as possible, and the metal is'then poled in accordance with the usual practice until it reaches the point where the specific gravityof cast samples will be at least 8.50. The copper thus preliminarily refined and rendered commercially gas-free nace, in accordance with the prior practice, in which prior practice the above indicated refining and degasify'ing operations have been carried out in stations remote from the casting furnace,

The present invention has for one of its objects the provision of a process and apparatus whereby electrolytically deposited copper cathodes may be submitted directly to a continuous casting operation, notwithstanding the presence 5. The speed of removal (casting speed) of themust be led into thecasting mold, additional prer from the mold must be controlled proppared copper being fed thereto at a location re-.

mote from the mold opening to avoid turbulence of the molten copper in the mold.

In the-commercial operation-of the continuous casting process as applied to copper and copper alloys, it has been foundthat an important factor to be considered in the practical-operation of the process is the presence of gases in the copper to be cast. Thus, for example, where electrolytic copper cathodes are being employed, there may be present gases such as hydrogen, water, and other gases, as well as saltsirom the electrolyte, so that if the cathode were simply melted down and cast, the casting would exhibit converted into a form 'wh made in the past,-and the economy of the prosuch as those mentioned above.

of the objectionable gases and other materials,

A further objectofthe invention is to provide an apparatus for continuously. casting copper, wherein the externally located refining stations are eliminated, and wherein the said preliminary refining and the continuous casting of the refined metal are performed in a single enclosure.

. Other objects and advantages of the present improvements will become apparent as the de-" scription proceeds, and the features of novelty will be pointed out in particularity with the appended claims. I

The particular application of the present invention is to providea process and apparatus which will enable copper cathodes to be directly ich is immediately suitable for fabrication. 'Many attempts have been posal is well recognized by many investigators. to use such cathodes to cast directly final refined V copper shapes. However, as has been mentioned above, these cathodes contain detrimental gases, such as hydrogen, water, and'other gaseous materials, as well as saltsfrom the electrolyte, sulphur,

and the like, so'that when they are melted down was introduced into thecontinuous casting furand cast they yield a casting with a very porous.

structure. Again, in all these attempts-to melt f cathodes, or refined copper mill scrap, intdrefined copper shapes for sale, the metal always becomes contaminated, particularly with iron, and also with magnesium aluminum, etc., from the refractories used in the furnaces, and here again there results a copper totally unfit for wire purposes in that the. conductivity is far too low.

This is the case even though the detrimental gases are removed, as has been described above, by separate and distinct operations for their elimination.

While the invention will be described with particular reference to the directconversion of coppencathodes into'oxygen-free refined copper by a continuous casting, operation, it will ,be apparent that, if' desired, other forms ofcopper, such as for example, wire bar copper may be utilized if desired in the present apparatus.

Although the features of novelty which are believed to be characteristic ofthis invention will be pointed out in particularity in the claims appended hereto, the inventionitself, as to its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, and which show the construction of an apparatus which is designed to.

,ing in thedirection of the arrows, and including the structural elements omitted in Fig. 1.

Fig. 3 is an enlarged sectional elevation of the casting mold and adjacent structure shown in Fig. 2.

' Itwill be understood that the particular furnace shown in the drawings is illustrative only as the specific details of the construction may be varied widely; also that it is not to be limited in its use to the continuous casting of copper cathodes, but that it may be used similarly for the continuous casting of other kinds of copper, as

' well as other metals and alloys.

Referring more particularly to the drawings, the furnace is shown as comprising a, refractory body In housed by a steel shell l2 and provided with a removal cover I8. This cover comprises a refractory body l4 enclosed in a steel shell I! 'and has a double seal I9 extending around the whole top of the furnace and formed by cooperating flanged members I l and I3 welded to shells l2 and I6, respectively. Sealing is appropriately I effected by filling the compartments formed by flanges II with sand or an equivalentgranular medium and with a non-volatile liquid such as a high petroleum distillate fraction, respectively.

Interiorly, the furnace is divided into two compartments, by a refractory vertical partition l3.

One of these compartments, I5, is the melting and refining compartment, and the other compart- 'ment l|.is the casting compartment. Communication between the two compartments ls afforded,

by duct 2 I.

The compartment l 5 is-lined with carbon blocks 23.. this lining extending overthe sides and bot- {tom of the compartments, the blocks 23 resting on a thicklayer of fire clay 25, which in turn 6 rests on heat insulating bricks 21, which are adjacent to the shell 12. The lower part'of partition I3 is fire clay with a carboncovering 29, the remainder of the partition l3.being built up of carbon blocks 3| to thetop of the furnace body. 10 The laboratory of the compartment l5 is'covered by carbon slabs 33. The carbon lined intake 35 for the metal has asloping bottom which opens tom being suillcient to allow thecathodes or other metal shapes being charged to slide freely down the slope and into the laboratory of the compartment- The compartment is heated to temperatures substantially above the melting point of the metal being cast by graphite resistor elements 31, 39, terminating interiorly of the furnace in terminal connector blocks 4|, 43. The graphite resistors 31, 39 pass through holes in the graphitesupport plate and connect the graphite blocks, 43

with graphite contact plates 41, 49, respectively,-

carbon slabs 33, and below carbon slabs 55, which cover the compartment 15 and form a ceiling therefor. Additionally,- the outer endof the intake is closed with a gas-tight door, not shown,

so that the interior of the furnace is sealed tightly against the outside atmosphere. With the'fur- 35 nace being, filled with an inert gas, preferably nitrogen, during operation it will be'a'pparent that the heating resistors and metal will be adequately protected against oxidation and contamination. Further, by reason of the close contact of the.

40 metal with its carbon environment on all sides, the metal becomes degasified sufficiently. to enab1e,it to be cast directly into oxygen-free metal suitable for direct fabrication. In this connec. tion it will be noted that the duct 2| is positioned closely adjacent to the bottom of the carbon slabs- 33 so that the metal fills almost up to these slabs' and its surface almost contacts therewith so that the metal is enclosed entirely in'a carbon environment, while becoming refined to a commercially gas-free condition.

The compartment I! is provided-with 'a graphite cr'ucible 23, one end 2|! of which subdivide's the compartment I! into a reservoir chamber 51 and a casting chamber 59. The passage or duct 55 2| in the wall l3 constitutes the path of flowfor metal from the chamber l5 into crucible 28, and a port ill in the crucible wall 20 constitutes the sole path of flow for metal from the chamber l1 into the mold or die 43.

Above the bottom of crucible 28 and supported by the sides of the crucible are spaced courses of graphite blocks, designated as 22, 24 and 24', which are in the nature of false bottoms in the crucible. The top course 22 of these blocks is beneath the cover 33, the slope of the intake. bot- 05 made shorter than the remaining courses, it terminating short of spout 63 of duct 2| which delivers the refined metal from the refining chamber I! to the crucible 28. At the right hand'side of the course 24 as viewed in Fig. 2, there is provided an opening or port 26 which delivers metal to the lower course 24, this latter being provided with a similar opening or port 26'- at its left hand side, through which metal flows to the bottom of ;the crucible 23, thence to mold 40.

port BI and casting,

. f the turbulence of'the metal, resulting from its v intake from spout 63, islbroken'up, so that it .fiows quietly and steadily to port BI, and also Q the metal becomes further deoxidlzed/before it through holes in the graphite support plate 56 "as is, also, a portion of the outside wall of the mold. The lower end of mold 40 is externally 7 13, 1939, for Apparatusfor continuously casting v I 2,26 "It will be seen thereforejthat on its ,way to complete contact with carbon, i. e., it flows be tween the blocks 22 and 24, through port 2 6,

then towards the left as viewed in Fig. 2, between the blocks 24 and 24, through port 26" onto the bottom ofcrucible 28, and then to the rightagain to theport, 20, the. metal. flowing between the 3 blocks 24' and the bottomi-of the crucible.

'Ihere, are thus performed two functions, 1. e.

reaches .the castlngmold 40, if it'was incompletely'deoxidized in the refining compartment.

c the 'mold' 40, the metal flows continuously in tion in part.

ass.

metals, of which this. application I continua- A seal is providedf'to preventlaccesspf air to the otherwise exposed ."surface' of. the exterrsion 66,0f the crucible 28, and mold 48. by means I ofa shell 14 provided with a channel-I6 filled with sand or 'other sealing mediuminto which Turbulence in the metal'in the mold is avoided further by arranging the port 6| 'to open. below I the mold intake.

Thecompartment'l'l; is heated electrically by graphite resistor elements horizontally positioned.

- between the crucible and mold construction, to

be described in detail hereinafter; and ceiling 42, which is made of graphite blocks or slabs and I supported bychannels in the furnace side walls. The heating elements comprise a pair of graph- I -ite resistor terminals 44, 46, terminating interiorly of the furnace in terminal connector blocks 48, 50. Graphite resistors 52, 54 pass and connect theconnector blocks 48, 50 with graphite contact plates 58, 68, which plates are extends sealing ring 1-8 when themold assembly I is in operative position; Non-oxidizing gas also may beintroduced intotheinterior of the mold,

as described in the aforesaid f Betterton and- Poland application in' order toprevent oxidation of the newcasting.

In view of'the fact-that any gases remaining in the metal after the above described refining treatment, are liberated from the metal upon solidification'thereof in the mold, and 11:15 desirable to maintain such liberated gases out of contact with themetal coming to the mold in order to prevent reabsorption thereof in the metalthe presence of such gases in the metal being "found in practice to cause seriousconnected with the support plate 56 by shorten graphite resistors '62, 64.

It will be seen that the crucible 28 has an extension 66 extending from the bottom of the end 20 of the crucible, and this extension has a hole through .its bottom for receiving the mold .48.

- This mold is machined from dense .graphite which meets the specification of U. S. Letters.

. Patent No. 2,136,394 dated November 15, 1938, granted to Frank F. Poland and Karl A. Lindner, and it is heldin place by holder 61 and graphitewasher 69, both of which are suitably threaded tapered towards its exit and is completely surrounded by a cooling jacket 68 of a metal with high heat conductivity, such as forged copper.

The said jacket is provided with intake 10 and a suitableoutlet, not shown, for circulation of cooling fiuidtherethrough, and thejacket is internally and inversely tapered to complement the external taper of the mold. and thus permit lenfulfillment of the conditions which have been gitudinal movement of the Jacket with respect to the mold.

Below this cooling jacket 68 there is provided 'a mold extension or auxiliary cooling jacket. in-

dicated generally at 12. the structural details of which are not shown, it being sufiicient to note in this connection that it is built up of a plurality of independent sections which when assembled are supported suitably in position, each section being composed of two separate complemental segments. which are joined yieldably by a conventional, bolt and spring arrangement.- Each segment has a suitable cooling fluid inlet and an outlet, and the segments are provided with liners 13 of ordinary graphite, which contact the cast rod.

These structural details are similar to theoperating difliculties, as has been mentioned above.

Consequently, means to' vent the gasis'provided. Suchmeans include a stack 80, which is T positioned directly above the intake of the mold -40 and extending through. the fumac roof; The

stack 88. has a vent opening 82 extending therethrough," the stack being secured in a graphitebase 84 by cooperating threads 86. The base 84 is in turn threadedly mounted in ,the crucible extension 66. The vent opening 82 educts from the furnace the gases liberated.

from the copper as solidification thereofoccurs in the mold, thereby reducing the sweeping mentioned previously herein as being important in the performance of the process on a satisfactory commercial basis.

It will be recalled that where copper cathodes is the material being handled in the process, the

operation must be conducted in view of the con-v dition of the metal, which may be high in oxygen, for example. Consequently there must be an effective deoxidation of the cathode metal in the furnace before it reaches the casting mold, and

the all-carbon surfaces with which the metal intimately contacts from the time it melts to the time it reaches the casting mold permit the metal to become deoxidized and commercially gas-free, the melting, refining-and casting as carried out in the direct manner as is described herein effecting important operating economies over the use of the usual operations wherethe copper. is. transferred intermittently from the casting" furnace from refining and holding units positioned atstations more or less remotefrom showing in the copending application of Better- 4 ton and Poland, Serial No. 267,688, filed April eliminating rehandling' of the metal during 7.5

the casting furnace, the improved procedure transfer operations and also the possibility of v the" continuous casting process produces oxygen-free, gas-free metal,

4 2,264,289 1 l preferablybeing' made self-adjusting with respect gas absorption during the transfer, together with a substantial shortening of the time interval heretofore consumed between, the melting ofthe to each other to accommodate cast rods of different diameters and between which the ,rod 82 passes. Either roll of eachpair maybe power of molten metal for supplying the-casting fun- All metal-contacting surfaces are of carbon,

-as is also true of the mold, so that from'the time the metal, such as copper-cathodes, is charged into the furnace and melted until the casting is withdrawn from the" mold, it is in' continuous contact, top, bottom and sides, with these carbon surfaces, and the time of passage.- of the metal through the furnace is such, that the metal, even whereit is gaseous metal such as cathodes, is transformed into,.and maintained in, the proper gas-free, deoxidized condition for direct conversioninto a continuous cast shape.

It will be seen that the metal from the refining chamber l5 overflows from that chamber through passage 2| and spout 63 into the driv'en from. a variable speed motor appropriately coupled to a speed reducer, the motor being responsive at all times to suitable rheostat.

control. After passing the rolls 89, 9|, .the.rod-

92 may be passed arounda guide 84, preparatory to passing to reducing dies.

It will be borne in mind that the rod 82 is a casting suitable for direct production of wire byv drawing. In order to produce a rod sufllciently'lon'g for. wire drawing operations, the rod 92 is bent at a suitable'distance above the cast- :ing floor at a guide roller '94, in a bend designat'ed at 88, andinyiew of the rod 82 being a ca'strod, the bend 86 preferably should be on an are having a long radius, for example, a threefoot radius for a rod of, say, about one inch in diameter.

shearing mechanism indicated at 88, which may crucible 28, this latter forming; a reservoirfor the refined metal, which flows to the casting mold through the passage 6|, thereby. maintaining a continuous supply oflmetal'in the mold.

By introducing the metal into the crucible through the spout. 63 and allowing it to cascade over the false bottoms 22, 24, 24' there isavoided turbulence in the metal undergoing solidification be anyone of several standard constructions. The rod is reduced in size for suitable shipment to wire manufacture, by passing it through one or morev suitable reducing dies, such as that indicated at I00, which reduces the rod to /4 in 'the mold, as well as completing the-deoxidation of the metal, and the construction and operation of the process is such that the casting operation proceeds without interruption. There is maintained continuously a supply of metal being refined in the chamber l5, and a continuous reservoir'of refined metal'in the crucible 28, which flows continuously to the mold as the casting proceeds, the crucible being fed by overflow of refined .metal from the laboratory of the refining chamber, this overflow being 0on trolled, in turn, by the introduction of fresh.

cathodes intothe charge-through the carbon intake '35. The importance of thus being able to replenish the supply offmolten metalin the that undergoing solidification .inthe mold must not be too highjat-any time if imperfections in the. casting are .to be avoided.

inch diameter, for example, it then being coiled on a reel IOI, also of large radius.

It has been noted previously that a nitrogen atmosphere is maintained in the furnace, the nitrogen being supplied to the furnace as substantially pure nitrogen gas, which is obtained in practice by burning out oxygen in carefully controlledquantities of air with city gas, butane or propane, the quantities being regulated so that combustion will be complete to water and CO2 without leaving residual oxygen and no substantial amounts of carbon monoxide. The resulting nitrogen, is passed through an absorbent for' CO2, e. g. -triethanolamine, and the nitrogen is then dried, and'passed to the furnace.

' Additionally, it has been noted previously that the present invention results in important opercasting operation is emphasized further when it It. will be understood that prior to charg ing the furnace, a suitable plug isprovided for the mold and mold extension which prevents the molten copper from running out of the mold prior to solidification therein Thisplug ordi-'- narily consists of the last part of the casting from a previous run and'constitutes the starting rod for withdrawing the casting from the mold. To initiate the actual casting operation, water is circulated throughthe mold to solidify the copper therein and weldit to the plug or starting rod which then is withdrawnslowly, the speed of withdrawal being increased gradually, with proper attention being paid to the mold cooling rateuntil the full commercial casting rate is attained and thereafter continued without jerking of the cast rod. For this purpose there are provided multiple pairs of flanged guide rolls, indicated '8t 88, 8|, the rolls.of each pair ating advantages. Previously to the present invention there were required at least two, and

preferably three, furnaces in addition to the cast- "and the like was skimmed oil. The melt-down. furnace was ,heated usually by a fuel such as oil and' the resulting products of combustion contaminated the. copper with sulphur and other noxious-materials, for the removal of which it became necessary to blow air through the molten charge,1.in order to burn out such contaminants. Incidentally some of the copper was oxidized. The blown copper is discharged into I a tilting furnace, where it was poled to toughpitch under coke or charcoal. This constituted the primary deoxidation treatment; further deoxidation-being accomplished by deoxidizing under a carbon blanket in the ladle which transferred for the casting furnace, it was highly desirable to provide two tilting iurnaces, one containing refined copper, the other copper being poled. Inaddition to-much labor, fuel costs, and repeated hon monoxide, in the presence of the carbon surraces in the furnace; the sulphates break down into sulphuric acid anhydride and copper oxide. Thes'e gases are present over and in the molten handling oi the metal, this procedure resulted If in a tie-up oi someten tons of copper for each casting mold. 7

' The present procedure eliminates all oi this.

The cathodes are simply washed clean with water and charged into the electrically heated car- 10.

bon furnace where they are melted and dear:-

idized in situ, while being swept by a current 7 of nitrogen gas. Since there are no combustion products or brickwork in contact with the copper, the blowing and skimming steps 01 the standard refining practice are eliminated; and l "as the deoxidation takes place in the carbon "furnace, the poling and secondary deoxidation in a ladle or ,by a carbon filter are avoided also,

a have a, common gas system.

been found that 1500 lbs. of copper per hour can as well as' the handling of moten metal which is go necessary in the transfer .of molten metal from the refining furnaces to the casting iurnacesx In accordance withthe present invention there is required only a single unit for each mold,

in whichunit both deoxidation and casting are accomplished, eliminating the various treatments and the multiple furnaces which were required previously to the present invention. 7 F

' Of course, the invention contemplates maki the refining section and the casting section, in-

' cluding the holding crucible, in separate parts,

with independently connected resistors. whereby flexibility of operation may be gained, as repairs may then be made to the sections more readily,- and a shut downof both of the resulting units is not necessitated for. making such repairs. In'

such an installation, the'deoxidizing unit may discharge. into the casting'unit by means of a metal overflow corresponding to the overflow 2|,

which discharges into the crucible'in the casting unit.- In such a modified constructiomboth units In accordance with the present invention, it has be readily cast directly from electrolytic cathup of about ten tons of copper for each mold in idrogen from the hydrogen in the bath; glue and lignone from addition agents; grease irom the jfrom the metal as cuprous chloride fume; the hyodes using a one-ton capacity iurnace in which there is a tie-up of only about one ton of copper foreach casting mold, as compared with a tieaccordance with the process as previously prac- 5o ticed.

A very important consideration in theproduction of sound continuously cast copper rod di rectly from the copper cathodes or other copper stock is the provision of the previously referred to inert sweeping atmosphere in the melting and casting units for the removal of noxious gaseous components which result from the melting of the cathodes. l

Since solid cathodes are charged into'the furnace without preliminary. refining, the small but so important amounts of contaminants in thecath odes go into the furnace in the metal. Such con taminants include chlorine from the hydrochloric acid addition agent used in the electrolyte; hy-

molten metal in the melting and casting units with an inert atmosphere nitrogen gas being the preferred sweeping gas,- as has viously herein. a 1

been stated pre- This nitrogen must be prepared very carefully to ensure its purity. The purer the nitrogen'the better it is for this particular purpose, and in practice it is prepared by burning a carefully controlled mixture of air with illuminating gas,

or such a mixture of airwith pentane'or butane,

the proportion of air with the combustible gas being such that all of the oxygen of the air is burned out, principally to'carbon dioxide with only, at most, traces or carbon monoxide, so that there results a mixture essentially. composed oil nitrogen, carbon dioxide and water.-- This mixture is passed through suitable gas absorbent equipment, wherein the carbon dioxide is removed by an eflicient absorbent, such as an ethanolamme, for instance either mono-, di-, or triphide or sulphur in the gas.

r The thus-treated gas which now contains 111- trogen, water, and possibly a little carbon monox ice and hydrogen is passed through activated alumina which extracts the water and lowers the dew point of the gas to -40 C. The resulting nitrogen contains generally not more than about 3% carbon monoxide, and generally not more than: 3% of hydrogen; and in practice it is very easy to hold these impurities below 1.5%. As pointed out above, .the purer the nitrogen is; the better.

The thus-treated gas, which now is essentially nitrogen, is passed through the furnace. Now,

copper-cathodes, in. addition to oxygen. contain appreciable amounts of the contaminants mentioned above, there being enough of them norpresent in' the cathodes to defeat completely the continuous casting process, which is inoperative with respect to the direct casting of copper cathode metal/unless these contaminants i are removed from the environment of the metal.

The nitrogen gas sweeps these contaminants out of the furnace, and transrorms an inoperative a fully commercially operative proposal into process;

As has been mentioned above, during the inelting or the'cathodes in the melting, umt, the

chlorine contained in th cathodes is evolved as' cuprous chloride, and'the hydrogenis liberated.

starting sheet; sulphates from the bath; oxygen. from exposure or the copper, to air; and water includedin the deposit. During the melting, the chlorine is evolved drogen is driven off as such; the glue, lignone,

and grease break down into miscellaneous gases;

the water breaks down into hydrogen and car- Also the oxygen in the copper is converted mto carbon monoxide, and the sulphates are decomposed-into sulphur trioxide'. The glue and grease are decomposed into miscellaneous gaseous materials. To a large extent such contaminating materials would not leave the copper, ordinarily, as they remain invthe copper in equilibrium with the atmosphere of the environment, in accordance with their partial pressures. Now, by sweeping atmosphere continuouslywith an inert gas,

I ethanoiamine, or a mixture thereof, which ab sorbs the carbon. dioxide .and any hydrogen suldioxide which may bepresent this equilibrium is destroyed and in attempting to restore it, these contaminants, all of which i arevolatile at the temperature-of thefumace,

leave the metal and are swept out of the environment as fast as they leave the me'taL- so that the metal is freed substantially from such i rod'for wire manufacture. is not asimple procedure, "and in fact until the discovery of the causes for the invariable failures of the attempts to directly continuously castcopper rods and the contaminants, only' slight traces thereof being left: in'the copper for liberation when the copper becomes solidified in the mold into arod which trolled-bye valve I04; and it is educted from the furnace through pipe I06, controlled by a valve I00.

IlO

discovery of the remedy therefor by sweeping the molten metal with an inert gaseous atmosphere, it was not possible to'operate to cast copper cathode metal directly .into sound rod, it being necessary to resort to the blowing and poling op erations, which the present invention obviates, in order to condition the metal for commerci continuous-casting operation; q

- Obviously the same precautions are appropriately taken, as describedin the foregoing de- It has been mentioned before that it is important tomaintain a low depth of metal over the mold 40, and in order to control such depth it is desirable to provide an indicating means for in- -dicating the approximate suitable level of metal over the mold Ill, beyond which level it is not desirable-to go.

The indicating mechanism includes a carbon rod H positioned suitably in recess Ill formed 'by the extension of the crucible 28, a port H2 positioned above the port, 6i affording communication between the interior of crucible 28 and the interior of the recess Ill, the lower end of the carbon rod H0 being positioned just above .this port 2, at the approximat preferred depth 3 of metal over the mold 40.

The rod I ll) extends through the roof of th furnace, and it is in circuit with a lamp" i I8, or

other equivalent indicating means, either visual or audible. A cooling coil' I" is provided for the scription, if alloying element are added to the copper cathodes, or other appropriate copper I stock hereinbefore suggested, to produce copperalloy rod.

What is claimed is: 1. Apparatus for continuously casting copper and copper alloy rod of high soundness for wire manufacture comprising furnacemeans defining metal-melting and metal-casting units, the

metal-melting unit being adapted to receive solid copper and tomelt the same, heating means in the' said unit adapted to melt the copper without subjecting the copper to combustion gases, a conupper end of the rod H0 and its connection with the indicating circuit, current from which is sup-' plied from a suitable source I20, a switch 122 being provided in the-circuit as control means. Consequently, when the metal level rises to where the-metal contacts the rod .I III, the switch 8 ll glows, thereby indicating to an operator that the metal level is such that no more metalshould be supplied to the mold 40 until the lamp is extinguished by the drop in -the metal level.

It will be seen also that a seal I22 is provided around the top of stack 80, where this stack extends through the furnace top.

It will be apparent that, in its broader aspects, the present invention includes the direct conversion of copper'cathodes into cast rod suitable for a direct drawing to wire, by melting the cathodes in a deoxidizing environment, sweeping away from the resulting molten metal, gaseous matebeing closed; a circuit is completed and the lamp tinuous casting mold rigidly mounted in the metal castingunit for receiving molten metal from the receiving unit, and means enabling molten metal, to pass directly from the melting unit to thee casting unit and thence without tupbulence to themold, the said apparatus presenting a continuous surface of carbon to the copper passed therethrough,

'2. Apparatus for continuously casting copper and copper-alloy rod of high soundness for wire manufacture. comprising furnace means defining a metal-melting unit, and metal-casting unit, means for heating therespective units, the saidmetal-melting unit being adapted to receive sol-i id copper and to melt the same therein, overflow means from the melting unit to the castingunit for transferring molten copper from the melting unit to the casting unit, a continuous casting mold rigidly mounted in the casting unit for continuously receiving molten copper from the melting unit, the said apparatus presenting a continuous carbonaceous facing to the copper from the time it entersthe melting unit until it leaves the mold, and means for indicating the depth of copper over the mold.

3. Apparatus for continuously casting copper and copper alloy rod of high soundness and density comprising a furnace interiorly divided into first and second compartments, means for introducing solid copper cathodes into the said first compartment, means for melting the said cathodes in the compartment, a continuous castrials hostile to the production of sound rod, and

continuously casting the swept metal into rod. Since the rod is a cast rod, and not a forged rod, due precautions should be taken in handling it to avoid such sharp bends asmight crack'the rod, and consequently it is preferred to coil the the rod on large drums, such as drum HII after the rod goes through the reducing dies, the radius of the drum being sufllciently long to prevent the rod cracking during coiling and uncoiling of the rod. A

From theforegoing description of the present invention, it will be apparent that the continuous casting ofcopper cathodes directly into sound fininga metal-receiving unit and a metal-casting unit, the interior of each of the said units being completely surfaced with carbon, electric accuse heating means in the, metal-receiving unit-for melting copper cathodesintroduced therein,.and S in the metal-casting unit for maintaining copper in the said metal'casting'unit at 'a temper'ature' substantially above its meltingto assuretull fluidity, of thecopper, overflow meansior the metal leading from the metal-receiving unitJto 8. The method of continuously casting copper ,7 oxidizing environment, effecting the melting and deoxidizing of the cathodes in situin the enthe Tmetal cas'ting unit, a continuous cajstingj mold rigidly mounted in the' metal-castingunit for continuously casting the metal in the said metal-casting unit, and means for. supplying,

. substantially completely free from turbulence,

the molten copper tothe said mold.

5. Apparatus for "continuously casting" copper I cathodes directly into sound and dense'rod comprising alpreliminary melting anddeoxidizingr chamber for the cathodes,;a secondary deoxidize ing-and casting chamber" indirect communic'aq .;ion withthe preliminary melting and dea'xidiz mg chamber for directlyreceiving molten copper therefrom, continuous casting .means in the. secondary chamber, means inthe chambers for de-. oxidizing the copper to be cast and ,forholding the said copper in substantially,completelmdeoxidized condition until completely cast; means i'or copper with the copper passing to the casting means and means for maintaining a circulating inert atmosphere over the copperin the chambers for sweeping out' materials hostile to the production of sound rod. I

6. Apparatus for" thewontinuous casting of copper rod directly from copper cathodes com prising .a nieltingchamber for receiving and melting the cathodes, means in the chamberfor deoxidizing the resulting molten copper in situ in the chamber, a casting chamberfor directly receiving deoxidized molten copperjrom-the deoxidized copper into a maintaining a supply offthe said'molten deoxi-, dized copper in the said casting environment ,25

pr v n Contact Eases d m pletely-"deoxidized condition, and continuously vir'onment until substantially completely deoxidized, directly passing the deoxidized molten melting-chamber, means in the casting chamber for continuously holding a pool of the deoxidized molten copper while maintaining the'copper in substantially completely deoxidized condition, a

continuous casting mold rigidly mounted'in the furnace including amelting chamber and a casting chamber, both chambers being completely lined with carbon, electric heating elements in both chambers to maintain copper therein at i temperatures substantially above its melting point, a carbon holder for the metal in the cast:

in chamber, a passage for leading molten copper from the melting chamber into the carbon holder in the casting chamber, a plurality of spaced vironment, directly passing the resulting molten ,mosphere orunabsorbable gas overthe copper in the chambers.

' supplied from copper cathodes which comprises introducing solid cathodes into a melting and decopper .irom thesald environment into a con-' tinuous casting environment,' and continuously casting the copper, while rendering. the copper- -in the-said environment substantially completely oxygen-free and gas-free by continuously sweep- .ing the copper (with an inert gas unabsorbable by the copper;

9. The method of continuously casting copper" supplied from copper cathodes 'which comprises 1 introducing the cathodes into a melting and deoxidizing environment, efiecting themelting and deoxidizing of the cathode copper in situ in said environment, overflowing the resulting molten casting. environment.

while holding the copper in substantially,com-

supplying the copper without, turbulence and in substantially as-free condition to continuous casting means as solidified copper is continuously withdrawn therefrom.

.10; ,The method ofv continuously casting copper supplied from copper cathodes which comprises introducing the cathodes into a carbon-lined "melting environment and melting the cathodes,

holding the resulting molten copperin said oncopper into a casting environment,- and' continuously casting the copperfromsthis latter environment while continuously "maintaining the copper in substantially completely deoxidized.

and gas-free condition by continuously -..sweeping the copper with a moving atmosphere ofan inert gas unabsorbable in the copper 11.1'I'he method of continuously casting copper supplied from copper cathodes which comprises introducing the cathodes intoia'. carbon-lined melting environment, melting, the cathodes therein, holding the resulting copper in said melting environment until substantially completely deoxidized, overflowing the copper from said environment directly into a carbon holder positioned in a carbon lined casting environment,

. said casting environment, and continuousl castmaintaining an-inert-atmosphere in both environments, forming a pool of the said copper in ing copper from the said pool while main aining the latter and, while sweeping the copper in the melting and casting environment with an inert layers of carbon spaced above the bottom, of the I holder and forming a multiple-floored. hearth therefor, ports in all upper floors disposed to cause copper flowing along the floors to cascade from one floor .to the next below, and to reverse its direction of flow along each succeeding floor,

thereby moving in a tortuous path completely enclosed, with carbon, ,a continuouscasting mold rigidly mounted in the casting chamber for continuously receiving copper from the holder, means for continuously leading copper from a pool'thereoi-in the holder to the mold, means for preventing turbulence of the copper at the mold, and-means for maintaining a moving atboth oxygen-free gas unabsorbable in the copper, thereby rendering the copper in substantially completely in casting.

12. The method of directly converting'copper cathodes into sound copper rod for wire manufacture which comprises melting copper cathodes,

and gas-free condition tor leading the molten copper directly and without turbulence to a continuous casting "mold; and

continuously casting the copper into rod while;

continuously-sweeping the, copper during melting and casting with an inert gas to remove con-' taminants of the copper from itsenvironment to produce soundcast rod. l

13. The method of directly casting copper cathodes into sound rod for wire production which comprises melting copper cathodes in a from, and continuously removing gaseous conmelting unit, directly flowing the resulting copper from the melting unit ,to'a casting unit while avoiding turbulence in the copper in the casting unit, controlling the depth 01 the copper in the casting unit, and continuously casting the copper into rod while continuously maintaining the molten copper in complete contact with carbon surfaces and while maintaining a moving atmosphere of inert gas in contact with the copper in the units to tree the copper from, and to sweep from its environment, contaminating materials.

14. The method as claimed in claim 13 wherein the inert gas is substantially pure nitrogen.

15'. The methodof converting copper cathodesdirectly into sound and dense rod, suitable for wire production, which comprises melting the cathodes in a deoxidizing environment while sweeping the resulting molten copper with an inert gas to degasify and remove irom contact with the said copper materials hostile to the production of sound rod, and directly continu- '-ously castingthe swept metal into rod, while continuously maintaining the'molten copper in intimate contact with the deoxidizing and detaminants from said environments by sweeping" same with an atmosphere non-absorbable by copper. L a

17. The method according to claim 16 in which the sweeping atmosphere is nitrogen. v

18, The method according to claim 16in which the sweeping .atmosphere is helium.

19. The method of producinga sound, continuous copper casting from copper stockcontaining gaseous impurities whichcomprises charging such stock to aflrst deoxidizing-environment, supplying heat thereto without introducing any'delete rious gases from the heating source, sweeping said environment with a gas non-absorbable by the copper, passing the copper into a second deoxidizing environment, and continuously casting the copper from said latter environment.

, 20. The method of producing a sound, continuous copper casting trom' copper stock contain- ,ing gaseous impurities which comprises charg- I ing such stock to a'flrst deoxidizing environ ment, supplying heat thereto without'introducing any deleterious gases from the heating replenishing the pool by charging copper stock to the pool and melting it therein, passing molten copper from the pool into the casting environment and continuouslycastlng the copper there source, sweeping said environment with a gas non-absorbable by the copper, passing the copper'into a second deoxidizing environment, continuously casting the copper from said second ,deoxidizing environment; and venting the gases constantly releasedv irom 'the copper being continuously cast in a manner preventing the entrance 01 such gases into 'said' second deoxidizing environment. 4

JESSE o. Barren-rpm W FR.ANK F. comma

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