US3182716A - Apparatus for cooling molten metals - Google Patents

Description

May 11, 1965 J MCNICQL ETAL 3,182,716

APPARATUS FOR COOLING MOLTEN METALS Filed Feb. 25, 1963' 2 Sheets-Sheet 1 M y 5 J. H. M NICOL ETAL 3,182,716

APPARATUS FOR COOLING MOLTEN METALS 2 Sheets-Sheet 2 Filed Feb. 25, 1963 United States Patent 3,182,716 APPARATUS FOR COOLING M'ULTEN METALS John Howard McNicol and Richard Henry Rowell, Port Pirie, South Australia, Australia, assignors to The Broken Hill Associated Smelters Proprietary Limited, Melbourne, Victoria, Australia, a company incorporated of Australia Filed Feb. 25, 1963, Ser. No. 260,562 Claims priority, application Australia, Feb. 27, 1962,

14,821/ 62; Dec. 20, 1962, 25,726/ 62 4 Claims. 7 (Cl. 165-12) For various purposes, it is required to cool molten metals. Thus, for example, the specification of our copending patent application Serial No. 250,397 discloses a process for the continuous copper drossing of lead bullion which operation requires the cooling of re-circulating molten bullion.

While molten lead, for example, may be cooled by passing it in contact with fixed water-cooled surfaces, some of the metal or its constituents usually freezes onto the cool surfaces and these deposits not only reduce the rate of extraction of heat but also they tend to choke the flow of the molten metal and are diflicult to remove.

Now the object of this invention is to provide an improved apparatus for cooling molten metals.

According to the invention, a liquid is cooled by causing it to flow through an elongated open channel and around and in contact with a plurality of immersion coolers arranged at intervals along the length of the channel. I e

The channel is preferably of deep and narrow shape in cross-section and the said coolers comprise suspended hollow members through which a coolant is circulated, the said hollow members being elongated in the lengthwise direction of the channel and of deep, narrow and downwardly convergent shape in cross-section. Such coolers are herein referred to as being of hollow platelike form.

Preferably, the cooling effect is regulated. by varying the number of coolers immersed in the flowing liquid, and for this and other purposes, provision is preferably made whereby each cooler may be individually raised and lowered to withdraw it upwardly from and return it to the channel. For this purpose, each cooler may be operatively connected to a pneumatic ram or the like.

When the apparatus is in use, accretions of the metal or constituents thereof form on each cooler as a more or less solid and continuous layer or shell which progressively increases in thickness as the operation proceeds. These deposited shells decrease the rate of heat transfer and also cause the level of the liquid in the channel to rise due to the reduction'in the effective cross-sectional area of the channel. a

It is therefore necessary to remove these deposited shells at intervals and, in some cases, this may be accomplished by temporarily cut-ting off the flow of coolant so that the shells are remelted by the hot liquid flowing through the channel.

Preferably, however, the deposited. shells are removed by lifting the coolers out of the channel and by maintainin the flow of coolant therethrough so that due to thermal contraction, the shells tend to split and drop back into the circulating liquid and are remelted therein. The

may be readily accomplished by moving the withdrawn coolers laterally out of alignment with the channel so that I the shells may fall off onto the floor or into a suitable receptacle. Alternatively, after the cooler-s have been withdrawn upwardly, an inclined chute or the like may be arranged below them to direct the shells laterally when they fall from the coolers.

The coolers may, according to requirements, be withdrawn sequentially or simultaneously from the channel for the aforesaid purpose and this operation is preferably carried out automatically under the control of timing means.

In order to maintain a constant cooling action, it is advantageous to Withdraw and return the coolers sequentially but on the other hand, when the discharged shells drop back into the channel, their discharge therefrom by the flowing liquid is impeded by any immersed coolers in advance thereof. For this reason, it has been found preferable, in the carrying out of the aforesaid copper drossing operation, to withdraw the coolers simultaneously so that the shells are more readily discharged from the channel. a

The invention also includes means for facilitating the delivery of the molten metal into the inlet end of the channel and means for facilitating the re-rnelting of the aforesaid shells after they are discharged from the channel.

By way of example, one practical application of the invention is hereunder more fully described with reference to the accompanying drawings in which: 7

FIGURE 1 is a View in plan of apparatus devised for cooling molten metal in carrying out the aforesaid continuous copper drossing operation,

FIGURES 2 and 3 are views in sectional elevation taken respectively on the lines 22 and 3-3 of FIG- URE 1,

FIGURE 4 is a view in sectional end elevation taken on the line 44 of FIGURE 3,

FIGURE 5 is a view in sectional elevation of an immersion cooler and is taken on the line 55 of FIG- URE 4, and

FIGURE 6 is a view in sectional plan taken on the line 7 66 of FIGURE 5.

discharge of the shells is assisted by the aforesaid down-;

wardly convergent shape, while in addition, the coolers, are preferably provided with solid wings which lose heat less quickly than the water-cooled body .of the cooler so that zones of Weakness areformed in the adjacent por- Referring now to these drawings, the reference numeral 10 designates an elongated open channel lined with suitable refractory material. -As shown in the drawings, this channel is straight when viewed in plan though it could be of any required shape, and our aforesaid prior specification shows a similar channel which is of U shape in plan. The inlet end of this channel is closed and is arranged above the top of an adjacent supply chamber 12 in which an approximatelyconstant level of molten lead is normally maintained while the opposite or discharge end of the channel is open and. projects above the top of a receiving chamber 14 to discharge the molten metal directly thereinto.

When the apparatus is in use, molten lead is continuously delivered into the. inlet. end of the channel 10 by means of a pump. 16 submerged within the chamber 10 and driven by an electric motor18 supported thereabove. A- small holding vessel 20 for the molten metal is arranged above the receiving end of the channel 10 and.

the pump 16 is connected to the bottom thereof by an upwardly diverging delivery pipe 24 and the holding vessel 20 is also provided with a short descending discharge pipe 26 which discharges the molten metal into v the channel without causing splashing.

' verging shape of the delivery pipe facilitates the discharge of solid accretions when they are dislodged by the scraper. Likewise, the upper end of the short discharge pipe 26 is similarly accessible so that blockages may readily be removed or prevented from forming, whereas when a pump delivery pipe with a downwardly bent upper end was previously used, accretions which formed therein could not be satisfactorily removed.

The channel 19 slopes downwardly at a small angle from its inlet to its discharge end and is of deep and narrow shape in cross-section as shown in FIGURE 4. Thus, in one particularly example, the channel was about thirteen inches deep to contain a depth of about seven to ten inches of molten metal without risk of spillage, while the sides thereof converged downwardly from the top where the width was about nine inches.

The channel 10 normally accommodates a plurality of immersion coolers 28 which are arranged in series along the length and centrally between the sides of the channel and close to, but above, the bottom thereof. The coolers, which are formed of thin plates welded together, are of hollow vertical plate-like form with downwardly converging sides and ends and may conveniently be about twentyfour inches in length, sixteen inches in height and two inches in thickness when the channel has the aforesaid dimesions in cross-section.

The top of each cooler is provided with fittings for the attachment of flexible inlet and outlet pipes 30 and 31 respectively for cooling water and the interior of the cooler is provided with battles 32 to cause the water to pass therethrough in a predetermined path.

Each cooler is suspended from a corresponding vertical.

pneumatic ram 36 mounted on a common frame structure 38 arranged above the channel in order that the cooler may be withdrawn upwardly from and returned to the channel and the cooler is maintained parallel to the length of the channel by guide rods 39 which project vertically upwards therefrom and extend slidably through fixed sleeves 40 on the frame.

As the molten lead flows past the immersed coolers, a layer of metal progressively solidifies thereon in the form of a shell or envelope 34 which extends around the sides and ends and below the bottom ot the cooler. As these shells build up, they progressively reduce both the rate of heat transfer and the eifective cross-sectional area of the channel thus causing the level of the molten metal to rise therein. It is necessary, there-fore, to removeithese deposited shells at suitable intervals and this is preferably accomplished by withdrawing the coolers from the channel as shown in FIGURES 2 and 3.

The flow of cooling water through the coolers is con tinued while they are removed from the molten metal, with the result that the shells quickly cool and contract so that they tend to split, and this action, in conjunction with the downwardly tapered shape of the coolers, tends to separate the shells so that they drop back into the molten metal and are eventually remelted therein. The discharge of the shells in this way may be further assisted by coating the external surfaces of the coolers with colloidal graphite or other suitable heat resisting solid lubricant.

In addition, however, and as shown in FIGURES 3, 4

and of the drawings, each end of each cooler is preferably extend-ed by a solid vertical wing 29. When the cooler is raised from the channel, these wings lose heat less quickly than the body of. the cooler with the result that zones of weakness are formed in the corresponding portions of the enveloping shell. Thus the shells tend to 'split vertically at each end so that the opposite sides turned to the channel sequentially in order that the total cooling eiiect within the channel remains substantially constant. It has been found, in the case of the aforesaid continuous copper drossing treatment, however, that when this procedure is adopted, a shell 34 which drops back into the channel when the coolers are withdrawn is not always quickly remelted so that it may tend to choke the channel when its progress towards the discharge end of the channel is impeded by an immersed cooler in its path.

For this reason when, as in the aforesaid copper drossing treatment, the consequent reduction in the cooling effect can be tolerated, it is advantageous to withdraw and return all of the coolers simultaneously, thus enabling the shells 34 to pass without obstruction to the receiver chamber 14. a

In either case, the withdrawal and return of the several coolers is preferably effected automatically at predetermined intervals under the control of any suitable timing mechanism, and for this purpose, a solenoid valve is preferably provided to control the supply of compressed air to and its discharge from the cylinder of each pneumatic ram 36.

In addition, a manually operable switch is preferably provided for each solenoid valve so that the respective cooler may be retained in its raised or withdrawn position.

Thus the rate at which heat is removed from the molten metal in the channel iiil may be regulated both by varying the number of coolers in use and also by varying the time during which each cooler remains immersed. The apparatus therefore permits of the effective regulation in a simple and convenient manner of the temperature of the molten metal discharged from the channel.

Referring now to FIGURE 3, a' propeller type agitator or stirrer 44 driven by an electric motor 46 is immersed in the upper portion of the body of molten metal in the chamber 14 and its purpose is to prevent the choking of the mouth of this chamber by unmelted fragments of the shells 34 discharged from the coolers. These shell fragments tend to fioat on the surface of the molten metal, in which case, they are remelted only slowly but the agitation produced by the propeller causes these fragments to be broken up and submerged so that they are soon remelted.

We claim:

1. Apparatus for cooling molten metals, comprising an elongated open channel for molten metal; said channel having opposed sides; said channel having an inlet end and a discharge end; means for continuously supplying molten metal to the inlet of said channel; a plurality of removable immersion coolers arranged at spaced intervals along the channel so that molten metal normally passes around and in contact therewith; each of said coolers comprising a downwardly convergent hollow body of vertical plate-like form having means for circulating coolant therethrough; a substantially vertically disposed solid wing formed on and projecting outwardly from each end of each cooler; said coolers being arranged centrally between and parallel to the opposed'sides of the channel; means arranged above and supporting the said immersion coolers; means operable to raise and lower the coolers thereby to withdraw them from and return them to the said channel; and timing means operable to control the raising and lowering of the coolers;

2. Apparatus for cooling molten metals, comprising an elongated open channel for molten metal, said channel having an inlet end and a discharge end; means for continuously supplying molten metal to the inlet end of said channel; a plurality of removable immersion coolers arranged at spaced intervals along the channel so that molten metal normally passes around and in contact'thereable to raise and lower the coolers thereby to withdraw them from and return them to said channel.

3. Apparatus for cooling molten metals, comprising an elongated open channel for molten metal, said channel having an inlet end and a discharge end; a plurality of removable immersion coolers arranged at spaced intervals along the channel so that molten metal normally passes around and in contact therewith; each of said coolers comprising a downwardly convergent hollow body of vertical plate-like form having means for circulating coolant therethrough; means arranged above and supporting the said immersion coolers; means operable to raise and lower the coolers thereby to withdraw them from and return them to the said channel; a holding vessel for molten metal arranged above the inlet end of the channel, said holding vessel being open at the top; a supply chamber for molten metal arranged below the level of the channel; a pump adapted to be immersed in a body of molten metal disposed in said supply chamber; a straight delivery pipe connecting the pump to the holding vessel at a position such that a scraper may be inserted downwardly into said delivery pipe through the open top of the holding vessel; the bottom of the supply vessel being formed with an aperture through which molten metal may gravitate therefrom into the channel.

4. Apparatus for cooling molten metals, comprising an elongated open channel for molten metal, said channel having an inlet end and a discharge end; means for continuously supplying molten metal to the inlet end of said channel; a plurality of removable immersion coolers arranged at spaced intervals along the channel so that molten metal normally passes around and in contact therewith; each of said coolers comprising a downwardly convergent hollow body of vertical plate-like form having means for circulating coolant therethrough; means arranged above and supporting said immersion coolers; means operable to raise and lower the coolers thereby to withdraw them from and return them to the said channel; a receiver for molten metal arranged below the discharge end of the channel to receive molten metal discharged from the latter; and agitating means so arranged in the receiver as normally to be immersed in a body of molten metal and near the surface of such body.

References Cited by the Examiner UNITED STATES PATENTS 301,394 7/84 Schlather 16586 997,762 7/11 Derrig 1651 19 X 1,119,801 12/14 Brigel 1031 1,727,216 9/29 Porter 1031 1,810,165 6/31 Frank et a1 16574 X 2,376,373 5/45 Merckel 165-74 X 2,633,435 3/53 Kopke 165-109 X FOREIGN PATENTS 38,818 6/86 Germany.

CHARLES SUKALO, Primary Examiner.

Claims (1)

1. 2. APPARATUS FOR COOLING MOLTEN METALS, COMPRISING AN ELONGATED OPEN CHANNEL FOR MOLTEN METAL, SAID CHANNEL HAVING AN INLET END AND DISCHARGE END; MEANS FOR CONTINUOUSLY SUPPLYING MOLTEN METAL TO THE INLET END OF SAID CHANNEL; A PLURALITY OF REMOVABLE IMMERSION COOLERS ARRANGED AT SPACED INTERVALS ALONG THE CHANNEL SO THAT MOLTEN METAL NORMALLY PASSES AROUND AND IN CONTACT THEREWITH; EACH OF SAID COOLERS COMPRISING A DOWNWARDLY CONVERGENT HOLLOW BODY OF VERTICAL PLATE-LIKE FORM HAVING MEANS FOR CIRCULATING COOLANT THERETHROUGH; AT LEAST ONE SUBSTANTIALLY VERTICALLY DISPOSED SOLID WING FORMED ON AND PROJECTING FROM EACH COOLER; MEANS ARRANGED ABOVE AND SUPPORTING SAID IMMERSION COOLERS; AND MEANS OPERABLE TO RAISE AND LOWER THE COOLERS THEREBY TO WITHDRAW THEM FROM AND RETURN THEM TO SAID CHANNEL.

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