US2465893A - Process for smelting and refining - Google Patents

Description

Mmh 29,1949. I L. M. LONG v 2,465,893

PROCESS FOR SMELTING AND REFINING Filed July 7, 1947 gin 0W Patented Mar. 29, 1949 UNITED STATES PATENT OFFICE PROCESS FOR SMELTIN G AND REFINING Leighton M. Long, Toledo, Ohio Application July 7, 1947, Serial No. 759,344

1 Claim. 1

This invention relates to remelting metal practices, more particularly in the establishment of alloy character or grading in the refining and smelting as of non-ferrous metals, as from scrap or miscellaneous sources.

This invention has utility in the preparation or forming of sections or ingots, with adaptability for ready handling and merchandising, including efficiency facilities for readily responding to definite and special formula or requirements in the ultimate use at foundry operations in casting production.

Referring to th drawings:

Fig. 1 is a vertical section thru a mold with an ingot, under the invention, therein;

Fig. 2 is a perspective View of a pig or ingot, say of brass or bronze in current practice as a foundry supply item;

Fig. 3 is a perspective view of an ingot under the invention herein, say as produced from the mold of Fig. 1;

Fig. 4 is a side elevation of a crucible, with parts broken away, showing charge therein of applicants ingots, for remelting at a foundry;

Fig. 5 is a View on an enlarged scale, with portions broken away, showing a special adaptability of the ingot hereunder in a melt to bring down the over-temperature from the melting heat to the range for the pour or casting, as well as incidental thereto, supply of a flux element or elements, as may be required for oxidizing or deoxidizing, as the particular situation may demand; and

Fig. 6 is a perspective view of a stack of ingots on a pallet.

The various substances in certain non-ferrous metal scrap of the general brasses and bronzes characteristics generally carry in varying proportions copper, tin, lead and zinc, of the differing alloys or compounds. Almost indiscriminately from heterogeneous sources, a practice current is to remelt into shallow open top molds in the production of pigs I, say in the range of 25#. Such a pig I at its small dimension or bottom may run 2" x 5" and when 3" deep or high, have its top or larger area face around 4 x 9". The top maximum side area exposes a large percentage of the metal body to oxidizing action of the air. Detrimental or less specific gavity inclusions rise to this surface as the melt for the pig tends to solidify. To clear the pig I from such Ill objectionable mass, a practice has been to skim before fully congealed. More favor has been met thru supplying a coating of powdered charcoal. This latter course tends to leave less rough places or irregularities 2. The carbon coating does not contribute to attractive appearance of the pig -I, and the carbon may, to some extent, be incorporated in the pig and to such extent affect or modify the analysis and the character of the product to be had therefrom.

These undesirable and objectional experiences are avoided under the invention herein. A multiple or single chamber mold may comprise a pair of sections 3, 4, relatively slidable into complementary register relation to form a mold chamber 5 having a relatively small area top 6. In carrying out the practice hereunder a cast or ingot T from a top pouring of a melt into the chamber 5 has its skum or impurities confined with the consequent almost total elimination of oxidation loss. The sides and bottom of the chamber 5 may be at least upon a A. radius edges, thereby avoiding sharp corners and occasion to wound the handler thereof. With the ingot 1 formed for say 1 square, it may be gauged for length, say for 20" for a saw off or cut 8 to sever a section 9 to include the scum and undesirable matter.

There is thus completed an article I9 as an ingot of definite shape, Weight and dimension. The ingot II] has four similar size and dimension rectangular parallogram long sides H extending between a pair of much less area square ends l2. These ingots I9 may be readily assembled into a stable stack I3 on a pallet 14. In warehousing, storage and. general handling practices, quantity identification is readily and reliably set up, and a transfer truck may enter beneath a stack on a pallet i l and take the stack l3 to and from storage.

When a crucible l5 has been prewarmed for a charge, the truck may bring the stack l3 into a convenient position for the operator or foundryman to take the ingots In from the stack l3 and insert the ingots on end in the crucible l5. In practice, the ingots 40 for remelting may be charged into various types of furnaces, such as reverberatory, and with the opening for receiving the charge as at a side or bottom. The ingots It being of considerable length as to their crosssection, may hav an end l2 thrust into the furnace opening, and as so directed, thrust suflici ently into the furnace to form a stack to be melted, or to become a part of a molten mass or pool. Considering the 25# pig I as having a surface in the range of 100 sq. in., this would make the exposure or face around 4 sq. in. per pound. In comparison the 20. ingot I has its surface range about 150 sq. in., or around 7 /2 sq. in. per pound. By taking the pig I to represent 100%, it is to b noted that there is 8'7 for the ingot I!) in its surface open to direct more heat attack. This is a direct heat efficiency advantage for the ingot I0, regardless of the character of remelting operation or the furnace therefor, as well as of the manner of placing or introducing the ingot I a into such furnace. With the heat on at the furnace, any symmetrical stackine may not be conveniently possible. That is, the throwing in of the ingots It may be sort of helter-skelter. Nevertheless, as introduced in a common or general direction, there is approximate parallelism in the usual grouping.

More specificaly, the crucible I5 may be taken as for say a 750# capacity of metal to be brought to the molten stage. With its available space approximating 3845 cu. in., a full charge into such hot crucible I5 would be about 16 pigs I or 400#. The actual displacement would net about 1250 cu. in. thereby leaving voids approaching 2600 cu. It is to be noted that this leaves over two-thirds voids and not quite up to half of the charge capacity for the crucible I5 to handle 7501i.

Notwithstanding the crucible I5 be hot, it is convenient and practicable for the foundryman to thrust the ingots II) on end thru the open top of the crucible IE to rest on bottom I6 of the crucible. The fact is that some 37 ingots I0 may be placed in on-end grouping conveniently in the crucible I5, thereby establishing a charge of 740# in bringing the charged crucible into the working range of its full capacity of 750#. With this charge having a displacement of about 2300 cu. in. as against 1250 cu. in. for the charge of the pigs I, there is 85% more metal in the crucible I5 to be made molten. The Voids now run with the ingots I0 and the charge of 31 into the crucible I5, to be under 1600 cu. in. as against 2600 cu. in. in the charge with the ingots I. The reduction in the voids thus shows as upward of 70%.

In foundry practice, a factor of safety may be adopted as to the temperature for the actual pouring into the molds for the castings to be produced. For instance, the optimum fluidity of an alloy for a certain type of casting operation may be 2150 F. In the handling of this job of pouring, the foundryman may bring the melt in the crucible I5 to the range of 2250 F. There is thus available 100 F. for drop in getting the molten metal into the molds. Furthermore, there may be occasion for final doctoring, which, if for temperature only, may be by introducing an additional ingot I0. Should there be need for oxidizing or deoxidizing, the ingot i0 may have an end pocket II for a flux capsule I8, retained by a plug I9, and tongs 20 used to place the treating agent I8 at the bottom of the melt 2 I.

The relatively minor exposed-to-air portion of the ingot I in the mold 3, l, normally requires quite an interval for cooling sufficiently that the set or congealed condition has developed shrinkage release so that the sections 3, 4, may be on side and slid apart to expose the ingot to have the} dross 9- trimmed Off. With the sides of the squares for the ends I2 of the ingot I0, under 2 as a maximum dimension, and the symmetrical cross-section ingot I0 having its remote or opposite end in the range of 20", there is multiple length dimension as to end or top. The polygon ends I2 have parallelogram sides upward of ten times longer than wide. The relatively slender overall appearance of the ingot II] means that heat travel into the ingot is quite a little less than 1" as a maximum. It follows therefrom that the extensive proportional surface area is a very material factor in the speed of heating operation. Considering the area relatively to the total mass of the ingot, there is a saving of nearly half; i. e., per pound, about half the heat units are required to bring the ingot I0 up to fusion, thruout, as for the ingot I. Further efficiency in the foundry practice is made possible by the fact that at a single charge the crucible may be brought to capacity for the melt. This avoids the course of less than capacity charge for the crucible. In the event the operator using the pigs I should seek to bring the crucible charge up to capacity, there is the chill for introducing the additional pigs I into the molten mass.

While the practically negligible air exposure top for the ingot I may eliminate greatly if not entirely occasion for deoxidizing, should there be need therefor, the counter-practice of oxidizing, or some special alloy, fiuxing or other treatment, such may be nicely and effectively handled, even without need for puddling or stirring, for by making the release of the capsule or charge I8 deep down in the molten mass, the forthwith melting thereof tends automatically to effect general permeation and uniformity.

What is claimed and it is desired to secure by Letters Patent is:

The methodv of foundry practice comprising,

'1 materially contributing to heat, material and labor economy, thru the performance in sequence of the steps of pouring a remelt of non-ferrous scrap metal into an open top mold to form an ingot blank with an air-exposed upper end area in the range of one tenth or less than a fiat side area of the blank length thereto, and with the blank approximating uniform cross-section thruout said length, separating a deleterious matter upper section by end gaging the blank to leave a refined homogeneous body metal ingot, laterally supporting a plurality of said ingots against a rising side wall of a crucible, with the ends of said ingots resting on the bottom of the crucible,

placing additional of said ingots side-by-side,

with said plurality of ingots to the range of 75% of the crucible melt capacity, fusing the cruciblecontained on-end ingots into a pool of a depth approximating 75% of the ingot length by simultaneously thruout minor crosssection decreasing the extent upward of the plurality of ingots, carrying the fusion heating of the pool to a temperature in excess of that for foundry pouring use thereof, partially utilizing the excess temperature to melt off an oxidation-control-agentcarrying special end of an additional normal temperature similar length ingot by thrusting said end of the additional ingot to the vicinity of the bottom of the pool, and, after the melting off of the agent and continuously therefrom, bringingv the pool down to normal pouring temperature by further utilizing said excess temperature to melt the remainder of the additional ingot into the. pool.

LEIGHTON M. LONG.

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

Number Newton et EL, Metallurgy of Copper, pub- 6 Name Date Pacz Aug. 24, 1926 Merten Mar. 15, 1932 Whitmore Sept. 10, 1935 Jung Feb. 6, 1940 Hughes July 29, 1941 Greenhow et a1. Aug. 12, 1941 Hulme et a1 Oct. 6, 1942 Prucha Dec. 29, 1942 OTHER REFERENCES lishecl 1942 by John Wiley 8: Sons, Inc., London, Chapman and Hall, Limited, page 218.

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