Oct. l, 1946. E. c. LYoNS _ 2,408,466 -MELTING MAGNESIUM METAL AND THE LIKE Filed Nov. 9, 1944 wm. INVENTOR. BY- - . @IMA ¿gi?-W» 17km; 1% l I v A-rToRNE‘Ys Patented Oct. 1, 1946 2,408,466 UNITED STATES PATENT OFFICE ` y - Y ~ 1 Y:nuit-’,466 Ü ` MEL'rING mGNEsIUt/_i' METAL AND > ` 'T-HE LIKE " ' Ellis C.'Lyons, Boulder City, Nev., assigner, by mesne assignments, to Reconstruction Finance Y Corporation, a corporation of theUnited Statesl _ ' 'Application November 9, 1944, serial No. A562,722 7 Claims. (C1. 266-33) This invention relates to the melting of mag nesium and magnesium base alloys, and has for its object the provision of certain improvements » 2 . with molten metal and communicates with the elongated molten metal reservoir. In the form of the apparatus particularly adapted for'remelt in the melting of magnesium and in the melting, ` ing clean and puriñed magnesium base alloys, the with or without refining, of magnesium and its 5 aforementioned receptacles are unnecessary for allOYS- , Y settling out impurities,- and either or both may be Magnesium is vcommonly produced by the elec- l. trolysis of a fused bath of magnesium chloride or by rreduction of Vmagnesium* oxide. The crude metal is characteristically contaminated with ox- 10 ide, chloride or other impurities which are cus- used for introducing molten metal into the reser Voir as molten metal is discharged- therefrom, or other‘suitable means may be provided for-such introduction of molten metal into the reservoir; The temperature of the fused salt bath may be tomarily removed by remelting and/or reñning controlled to maintain the molten metal in the the molten metal. The reiined metal is usually reservo-ir within a predetermined temperature alloyed with other metals to impart desirable Tange- hardening and corrosion-resisting qualities there- 15 to for structural and other mechanical and commercial uses, as, for example, in the automotive and aircraft industries. Among the many magnesium base alloys so used may be mentioned, ' The foregoing and other novel features of the invention which I believe to be patenta'ble are set forth in thev appended claims. The prin ciples of the invention will be best understood from the following description taken in con merely by Way of example, the magnesium-alu- 20 junction with the accompanying drawing, in minum-zinc-manganese alloys -containing 0.1 to which the single ñgure is a side elevation, partly .12% aluminum, none up to 5% zinc, none up to iny section and somewhat diagrammatic, of an 3% manganese, >and the balance essentially magapparatus embodying the invention. nêsium- ` ‘Y f Y `Referring to the drawing, an insulated tank 5 The meltingVV and reñning of the crude metal 25 holds _a fused salt bath'ß. The bath 6 may be and the production of .magnesium base alloys is heated by any convenient means but is prefer customarily carried out at the plant where the ablyheated by one or more pairs of electrodes 7 magnesium is produced or in plants for refining electrically connected to a suitable source of elec and alloying magnesium. On the other hand, tricenergy B thro-ugh a thermostatic control de magnesium base alloys are customarily remelted l" vice 9 including a pyrometer ID thermally asso and -cast in foundries for manufacturing Ystruc tural and other mechanical articles of the alloy. ~ The present invention contemplates an im proved apparatus for melting and refining'crude ciated with the bath. An elongated conduit or molten metal reservoirV I I is submerged in the fused salt bath 6. The conduit is in the form of an oval coil extending magnesium and for melting magnesium-base `al-’ ,-35 from near the top to near the bottom of the bath loys, with or Without refining. In its broad aspect, and is appropriately supported by standards I2. the apparatus of the invention comprises an elonThe upper end of the conduit I I communicates gated molten metal reservoir immersed in a fused with the upper end of an enclosed receptacle or salt bath, with means for introducing metal into settling unit I3 completely submerged in the‘fused the reservoir under conditions inhibiting oxida- Lio ysalt bath.y A second receptacle or settling’unit tion, and with a Valve-controlled discharge for Ul is immersed in the fused salt bath. The re the reservoir, the reservoir being so constructed ceptacle I 4 is open at its top, above the level of that in'operation it is iilled with molten metal the bath, and is connected to the receptacle I3' Which flOWS 'by gravity from the point of intro# by a conduit I5 at a level slightly below the com duction thereto to the point of discharge there# 45 munication of the receptacle I3 with the elo-n from. In the form of the apparatus 10211131011gated conduit II. The conduit I5 may advan larly adapted for use in melting and reñhîng tageously slope upward from the receptacle I4 crude magnesium, the melted metal iS held in tothe receptacle I3. The receptacle Id has arde two receptacles immersed Vin the fused salt bath pending drain |5 with> a, discharge valve :1 a1; and ?communicating with each other beneath the the bottom. thereof The receptacle |3 has a. molten metal level, and in' which impurities are` similar depending drain IAB with a discharge valve permitted to settle out. One of the receptacles i9. A heating coil 2o surrounds the lower end of may be open to the atmosphere and the crude each drain ‘I5 and I8, exteriorly of the bottom metal introduced into the top thereof. The other of the tank 5, to prevent freezing of the metal and receptacle may be completely enclosed and is ñlled . impurities in the drains. The lower end of the 2,408,466 3 elongated conduit II communicates with a dis charge conduit 2 I having a valve-controlled metal outlet 22. The conduit 2| and Valve outlet 22 may be heated to prevent freezing of the metal. The apparatus illustrated in the drawing is particularly adapted for magnesium refinery op eration. Molten metal, solid pigs or shapes, scrap, and the like may be advantageously treated in the apparatus to separate therefrom the asso ciated impurities such as particles of salt (cell melt), flux, oxides etc. which may contaminate the crude metal. The crude or contaminated metal to be treated, for example the pig 23 illus trated inthe drawing, is introduced into the open upper end of the settling unit I4. Solid metal so introduced is melted by the heat of the fused salt bath. The impurities, being heavier than the molten magnesium metal, settle towards the ‘bottom of the unit I4 and may be removed from time to time through the discharge valve I1 of said reservoir for introducing molten metal into the reservoir when molten metal is discharged from the reservoir. 2. An apparatus of the character described comprising an elongated and substantially closed molten metal reservoir submerged in e. fused bath without communication between the interior or said reservoir` and the material of said bath, a settling unit submerged in said bath and com municating near its upper end with one end of said reservoir and having a discharge in its bot tom for settled matter, a Valve controlled dis charge means for the other end of said reservoir, and means for heating said bath. 3. An apparatus of the character described comprising an elongated and substantially closed molten metal reservoir submerged in a fused bath without communication between the interior of said reservoir and the material of said bath, a settling unit submerged in said bath and com municating near its upper end with one end of said reservoir and having a discharge in its bot place in the settling unit I3 and may be removed tom for settled matter, a valve controlled dis from time to time through the discharge valve charge means for the other end of said reservoir, I 9 of the drain I8. Substantially pure metal-is said reservoir being so constructed that in oper delivered from near the top of the settling unit 2:5 ation it is filled with molten metal which flows I3 lto the elongated conduit Il. by gravity from the end communicating with said The fused salt bath 5 is thermcstatically con settling unit to said discharge means, and means trolled to bring the molten metal in the elongated operatively associated with said bath for heating conduit II to the proper casting temperature. This vcan be accurately accomplished in the ap 30 the same and maintaining the molten metal in the drain I6. Further settling of impurities takes paratus of the invention, since the salt bath assures uniform heating of the metal in the con said reservoir within a predetermined tempera ture range. el. An apparatus of the character described comprising an elongated and substantially closed duit within narrow ytemperature limits. Purified molten metal is withdrawn from the conduit II, as required for casting, through the outlet 22. 35 molten metal reservoir submerged in a fused bath without communication between the interior of Casting may be carried out in sand molds, per said reservoir and the material of said bath, a manent molds, or the like. Except for the open settling unit submerged in said bath and com charging .top of the settling unit I4, the parts of municating near its upper end with one end the apparatus holding molten metal are com pletely enclosed, and the molten metal is effec 40 of said reservoir and having a discharge in its bottom for settled matter, a second settling unit tively protected against oxidation or other con open at its top and for the most part submerged taminating influence. The conduit II is at all in said bath and having a discharge in its bot times completely f1lled with molten metal, and tom for settled matter, said settling units com `the contemplated flow of molten metal through municating with on-e another intermediate their the apparatus results from the action of gravity. ends, a Valve controlled discharge means for the The elongated conduit or molten m-etal res other end of said reservoir, and means for heat ervoir I I may be made of steel, such as ste-el pipe. ing said bath. Such a metal conduit submerged in the fused salt 5. An apparatus of the character described bath has little tendency to scale, rust, pit or comprising an elongated and substantially closed corrode, and hence has a long life. Similarly, molten metal reservoir submerged in a fused bath the receptacles I3 and I4 and conduit I5 may be without communication between the interior of made of steel. said reservoir and the Ymaterial of said bath, a The fused salt bath may be heated in any settling unit submerged in said bath and com appropriate manner, the electrodes and asso municating near its upper end with one end of ciated devices being described and illustrated said reservoir and having a discharge in its bot merely by way of example. Thus, electric resist tom for settled matter, a second settling unit ance units, submerged pipes through which hot open at its top and for the most part submerged gases pass, etc. may be substituted for the elec in said bath and having a discharge in its bot trodes. tom for settled matter, a valve discharge means The invention while particularly adapted for for the other end of said reservoir, said settling treating magnesium and alloys thereof, may be units communicating with one another interme employed with advantage in treating other easily oxidized metals. ,I claim: l. An apparatus of the character described comprising an elongated and substantially closed molten metal reservoir submerged in a fused bath without communication between the interior' of said reservoir and the material of said bath, means operatively associated with said bath for maintaining the molten metal in the reservoir within a predetermined temperature range, a valve controlled discharge means operatively con nected to one end of said reservoir, and means diate their ends `and below the communication of said reservoir with the first mentioned settling unit, said reservoir being so constructed that in operation it is iilled with molten metal which flows by gravity from the end communicating with said first mentioned settling unit to said discharge means, and means for heating said bath. 6. An apparatus for melting an easily oxidized metal comprising an elongated and substantially closed molten metal reservoir submerged in a fused Ibath without COmmunication between the operatively associated with the other end of 75 interior of said reservoir and the material of said 2,408,466 v bath, onevend of said reservoir being adapted to receive molten metal melted rby the heat of said bath, and a Valve-controlled discharge means for the other end of said reservoir, said reservoir being so inclined that molten metal ñowsthere through by gravity. , _ ì f y 5 y 7. An apparatus for melting an easily oxidized metal comprising an elongated and substantially , closed molten metal reservoir submerged in a rfused bath withoutcommunication between the 10 interior of said reservoir and the material olf said lbath, means for introducing molten metal melted by the heat of said bath into said reservoir under conditions inhibiting oxidation, and a valve-con trolled discharge means for said reservoir, said reservoir being so constructed that in operation it is ñlled With molten vmetal which flows by gravìtyrfrom the point of introduction thereto to the point of vdischarge therefrom. ' f ELLIS C.y LYONS. .