US2252697A - Manufacture of metal products - Google Patents

Description

Aug. 19, 1941. H. A. BRAssERT MANUFACTURE OF METAL PRODUCTS Filed Feb. l, 1940 S @Ek El INVENTOR ,s/@WZZM Patented Aug. 19, 1941 UNITED STATES PATENT OFFICE MANUFACTURE OF METAL PRODUCTS Herman A. Brassert, New York, N. Y., assignor to Minerals and Metals Corporation, New York, N. Y., a corporation of Delaware Application February 1, 1940, Serial No. 316,717

7 Claims.

dined to some extent, and then cast or deformed into the desired products, frequently accompanied by intermediate steps. In the production of steel products the iron ore is first reduced in the blast furnace to pig iron and conveyed in the molten state, or cast into pigs and remelted with or without the addition of scrap. The molten iron is blown in a Bessemer converter and cast into ingots or is further rened in the open hearth furnace with the addition of scrap. In most cases, however, -the open hearth furnace is used to convert molten iron and scrap into steel. In any case the metal is cast into ingots, reheated in the soaking pits, then formed into blooms and billets, with or without intermediate reheating steps, before it is nally rolled or otherwise shaped into the finished product. Wrought iron is produced in the puddling furnace, or by mixing blown metal with slag, forming the material into a ball Without bringing it to the molten state, squeezing the ball to remove excess slag, and forming it into blooms for rolling, with intermediate reheating operations. These necessary steps are laborious, expensive and time-consuming and contribute to the cost of making the finished products, and if one or more of them could be eliminated without sacricing quality in the finished product, the cost of the latter would be proportionately reduced.

In accordance with the present invention,` a process and apparatus are provided for manufacture of metal products directly from finely-divided reduced ore without the necessity of intermediate rening or melting steps and one or more of the reheating steps.

In a preferred embodiment of the invention, sponge iron is produced according to a known process, and is prefarably supplied in nely-divided form from the reducing furnace or collector in the presence of the reducing gas or other nonoxidizing atmosphere, or after admixture with desirable modifying elements or compounds. While retaining at least part of the residual heat of the reducing process, with or without an intermediate heating step, the material is fed to a press where the particles are compressed while hot into cohesive contact under suliicient pressure to form a self-contained dense billet of strength suilicient to prevent disintegration under subsequent deforming operations and having dimensions commensurate with the requirements of the subsequent operations. This compressed billet is directly discharged to a heated zone where it is heated to the welding temperature to provide a perfect weld between the contacting particles, preferably still under non-oxidizing conditions.

' While so heated the billet is directly supplied to a rolling mill, press, hammer, drawing die, extrusion press, or other metal deforming apparatus for working and shaping into a Vfinished or partially-iinished product of satisfactorily homogeneous internal structure.

Similarly, for manufacturing tubing, the finelydivided metal, after a direct reducing operation and while substantially at the temperature of the final reducing or concentrating step, is charged into a press comprising a cup-shaped outer die, and a force or plunger for compressing thev finelydivided material into a self-contained hollow or bottle having the physical properties described, which is then heated to the welding point of the metal to weld the particles together, and the hollow or bottle while so heated is repressed to more accurate dimension for pushing through a ringbed or dies, or pierced for rolling in a tube mill over a mandrel, or drawn or extruded, in any of the conventional Ways to produce the finished seamless tubing.

The ores and oxides of non-ferrous metals in nely-divided form are treated in the same way to produce finished metal products, the temperatures and pressures utilized being commensurate with the physical characteristics of the metal selected.

It will be seen that with the process and apparatus of this invention, metal products of great purity and high tensile strength may be manufactured on an economical basis in competition with the usual time-consuming present processes, while, in the case of iron and steel, eliminating the necessity for coke plants, blast furnaces, open hearth furnaces, puddling furnaces, Bessemer converters, and much ofthe auxiliary equipment, with the result that metal products including alloys may be produced having exceptional physical and chemical qualities.

For a more complete understanding of the invention, reference may be had to the accompanying drawing, in which:

Figure 1 is a diagrammatic representation of apparatus for conducting the process of this invention; and

Fig. 2 illustrates diagrammatically the formation of a hollow or bottle for the manufacture of tubing.

The material to be treated is preferably an ore, from which sponge iron in powdered or granular form may be produced, although the product of the reduction step may well be a finely-divided, non-ferrous metal, or mixtures thereof, depending upon requirements. The chief raw material source for sponge iron is rich iron ore, generally magnetite, which is crushed, pulverized, and magnetically concentrated, or the-ore may be concentrated iron sands. The powder resulting from magnetic concentration is then reduced with charcoal or other finely-divided carbon or it can be reduced by reducing gases, or by carbon derived in cracking natural gas or oil, or by a combination of reducing gases and solid carbon, all in accordance with known processes. Alternatively, lump ore may be reduced to sponge iron according to, a known process and then crushed or ground to finely-divided state.

In the arrangement illustrated in Fig. 1, the sponge iron is supplied directly from the reducing furnace I, in finely-divided form, after separation of the reduced ore from the ash and the like in a cyclone separator 2, for example, while retaining much of its residual heat, and in the absence of oxygen to preclude oxidation. For this purpose, the reduced'ore may be conveyed to separator 2 through a duct 3 from the furnace in the presence of the reducing gases or the spent or partially spent reducing gases, which provide a non-oxidizing atmosphere. From the cone 4 of the separator 2 the reduced ore particles are conducted by gravity through duct 5 and normally open gate valve 6 into the measuring chamber 'l formed in the duct between normally closed gate valve 8 and valve 6. When chamber 1 is filled, gate 6 is rst closed and then gate 8 is opened to discharge the measured quantity. the volume of which depends upon the determlned compression thereof in the subsequent compressing operation.

The measured reduced ore may have admixed therewith, if desired, certain modifying agents, such as soda, fluorspar, or other fluxes; or elements, such as carbon, silicon, sulphur, manganese, nickel or chromium in the form of reduced ore; or alloying metals or metallic compounds, such as ferro-manganese, ferro-silicon, ferro-titanium, or other alloys or alloying compounds of different chemical constituencies; or mixtures of one or more of the foregoing, and the like, which are introduced for the purpose of modifying the physical or chemical properties of the finished product, or both. If these modifying agents are to be added to the reducedore, the latter is discharged from measuring chamber 'I into mechanical mixer 9 having its beater driven by an electric motor I0 or the like. 'Ihe modifying agents are added to the mixer 9 by means of a hopper Il through a gate I2, which precludes the ingress of air. The mixing is intimate so that the agents are uniformly distributed through the reduced ore. The quantity of the modifying agents is usually relatively small, but may be great as required, and, if relatively great, the measuring device 1 is adjusted to compensate for the added quantity so as to maintain the proportion of size of charge to the desired volume of the compressed billet. Alternatively, the measuring device 1 may be placed after the mixer 9. If modifying ,agent-,s are not to be added, the mixer 9 is not used.

From the mixer 9 the material is preferably passed into a suitable furnace I3 to be heated to a temperature which will aid in the mechanical cohesion of the particles, but at a temperature lower than the fusion point of the material or mixture, so as to preclude sticking of the material to the walls of the apparatus. For example, for sponge iron, the temperature to which the material is heated in furnace I3 may be approximately 1500 F., although the temperature of the furnace may be higher to compensate for the heat loss between it and the compacting point.

The heated material is discharged through the gate I4 into the cylinder I5 of a hydraulic press, the plunger I6 of which is adapted to be operated by a suitable hydraulic ram I'I of conventional design. The end of the cylinder I5 is normally tightly closed by a heavy gate I8 between which and the plunger I6 the finely-divided material supplied to the cylinder I5 is compressed into a dense, self-contained billet B in which the finely-divided particles are in intimate cohesive contact with each other and no voids between them are visible or apparent.

The billet B so formed is preferably of relatively large size, comparable to the billet of conventional rolling mill or hammer or forging press practice. The pressure required for compressing the finely-divided metal must be sufllciently great that the billet B is sulciently strong, i. e., has sufficiently consolidated grain structure to stand the subsequent handling, such as rolling, forging, drawing, or the like, without'disintegration. For example, for a billet of sponge iron of dimensions roughly six inches square in cross-section and four to six feet long, soheated and formed of particles passing a mesh screen, the pressure necessary to compress it to the desired compactness and density is from two to four tons per square inch. However, it will be understood that the pressure varies in accordance with the size of the particles, the temperature thereof, the ultimate size of the compressed billet, and the like, and it is to be understood that the temperature and pressures herein given are merely illustrative of a practical example and are not to be taken as limiting the invention.

After the compression of the material into the billet B, plunger I6 is slightly retracted to relieve the pressure on the gate I8, so that the latter may be lowered by suitable mechanism to open the end of the cylinder I5. The plunger I6 is then again advanced and the billet B is pushed thereby from cylinder I5 directly into furnace I9 upon a slowly moving steel belt conveyor 20. While slowly moving through furnace I9 the billet B is heated to the welding temperature, that is, the temperature required to consolidate the grain structure throughout the interior of the billet, which, for a pure sponge iron in the example contemplated, is on the order of approximately 2500 F. vAt this temperature the contacting particles soften and weld together but the billet does not melt. It will be understood that the temperature in the furnace must always be somewhat higher than the temperature of the piece to be heated.

After being heated to the required temperature 1n furnace I9, the billet B is conveyed by'conveyor 20 directly into the rolling mill 2l where it is worked to compact the particles into a welded mass having a homogeneous structure, and having .its physical and chemical characteristics modified as and if desired by the modifying material previously added at point l I. The rolling mill 2| is conventional and the finishing rolls thereof form it into the desired cross-sectional shape, such as bars, shapes, sheets,I and the like. For reduction into rods or Wire, the material is supplied from the roughing mill 2| to the conventional draw benches or extrusion presses, not shown. Instead of utilizing a rolling operation as provided by the mill 2|, the billet may be forged or swaged in a hammer, press or the like, depending upon requirements.

It will be understood that the entire process is continuous without time delays, each step fol1owing the preceding one, thus enabling high rates of rolling and making use of the residual heat in every step to minimize reheating and alteration of the grain structure except as effected in the process. The process is preferably conducted in a non-oxidizing atmosphere not only up to and including the press cylinder I as described, but also preferably throughout the heating step in the furnace I9. By sealing furnace I9 and the rolling mill 2| and supplying a suitable non-oxidizing atmosphere thereto, the oxidation of the metal may be prevented throughout the entire process, whereby the original purity of the material may be retained.

Instead of heating the finely-divided material in preheatingfurnace I3, the cylinder l5 may be heated, or Aboth sources of heat may be employed. Also, other methods of heating the material to facilitate compressing may be employed, such as high frequency electric current supplied to a coil surrounding the supply duct or the cylinder l5, or both. For large billets, additional compression of the material may be desired, in which case a second stage press, similar to I5, I6 may be provided, or an additional press for compressing the material from two or more sides instead of at one end as shown, the practice of continuous feeding beingretained in each case.

Fig. 2 illustrates the adaptation of the invention to the manufacture of hollow products such as tubing. The plunger I6 is shaped as shown, with a cylindrical portion 22 and an axially extending conical portion 23. The finely-divided material is blown into cylinder I5' under pressure through a plurality of ports 24 supplied from a header 25, the pressure being furnished by a non-oxidizing gas. The material impinges on the sides of the conical portion 23 and by reason of the shape of the latter, the material is distributed uniformly throughout the interior of the cylinder I5' until the space between the cylinder 23 and gate |8' is tightly filled. Thereupon the plunger t6 is advanced by the hydraulic ram as before and compacts the material into the cupshaped hollow or bottle C, which is self-contained and uniformly dense because of the lateral as well as axial pressure produced by the conical portion `23, by reason of its shape. Portion 22 seals ports 24 during compression.

After the pressing operation plunger I6' is slightly retracted, which breaks the connection of the conical portion 23 with the hollow or bottle C, which remains fixed, being held in place by friction on the cylinder I5. The pressure on gate I8 being relieved, it may be lowered to permit the plunger I6' to push the hollow or bottle C from cylinder I5' onto the conveyor 20. The plunger I6 is then retracted, leaving C on the conveyor which is possible without dragging C, because there is little or no sticking between them, C having cooled slightly and contracted to permit ready withdrawal of the conical portion 23.' Gate Il is reclosed and the operation is repeated while the bottle or hollow C is wash-heatand rolled over a mandrel, or by any other tubemaking process, into a seamless tube or the like, in the usual way, with or without an intermediate re-pressing and reheating operation.

While certain preferred embodiments of the invention have been illustrated and described herein, it is to be understood that the invention is not limited thereby but is susceptible of changes in form and detail within the scope of the appended claims.

No attempt is made herein to claim a process or an apparatus,.the end product of which is a marketable solid produced by consolidating freshly reduced ore, while in its nascent condition, without an intermediate heating step. Claims to the last-mentioned process and apparatus are being made in my co-pending application Serial No. 369,053,V filed December 7, 1940.

.I claim:

1. The method of forming metal products, which comprises the steps of reducing ore in a reducing zone without melting, compressing the reduced ore in finely-divided form into a selfcontained mass while it retains at least part of the heat of the reducing step, further heating the mass to the welding point to weld the reduced ore particles together, maintaining said reduced ore under non-oxidizing conditions during and between said steps and then deforming the mass while so heated, the said several steps being immediately successive in a continuous process.

2. The method of forming metal products, which comprises the steps of reducing finely-divided ore in a reducing zone without melting, compressing the reduced ore in finely divided form into a self-contained mass while it retains at least part of the heat of the reducing step, further heating the mass to the welding point to weld the reduced ore particles together, maintaining said reduced ore under non-oxidizing conditions during and between said steps and then deforming the mass while so heated, the said several steps being immediately successive in a continuous process.

3. The method of forming metal products, which comprises the steps of reducing ore in a reducing zone without melting, finely-dividing the reduced ore, compressing the reduced ore in iinely-divided form into ra self-contained mass while it retains at least part of the heat of the reducing step, further heating the mass to the welding point to weld the reduced ore particles together, maintaining said reduced ore under non-oxidizing conditions during and between said steps and then deforming the mass while so heated, the said several steps being immediately successive in a continuous process.

4. The method of forming metal products, which comprises the steps of reducing ore ina reducing zone without melting, heating the reduced ore, compressing the reduced ore in finely-divided form into a self-contained mass, further heating the mass to the welding point to weld the reduced ore particles together, maintaining said reduced ore under non-oxidizing conditions during and between saidcsteps and then deforming the mass while so heated, the said several steps being immediately successive in a continuous process.

5. In apparatus for making metallic products,

the combination of means for reducing ore in finely-divided form without melting, means for separating the reduced ore from the other products of the reduction, a press. means for supplying the heated reduced ore to said press, means for actuating said press to compact the -reduced ore into a self-contained mass, a furnace for heating the mass to the welding temperature of the particles composing it, means for transferring the mass to said furnace, means for maintaining a non-oxidizing atmosphere in said means, press and furnace, a deforming device, and means for transferring the heated mass to said device for deforming the same into a metallic product.

6. In apparatus for making metallic products.

from finely-divided reduced ore, the combination of a furnace for heating the reduced ore, a press, means for supplying the heated reduced ore to said press for compression of the same into a self-contained mass, means for maintaining a; non-oxidizing atmosphere in the preceding means, furnace and press, a second furnace for heating the mass tothe welding temperature of the particles composing it, means for transfer-v ring the mass to said second furnace, a deforming, in nely divided condition, an ore at tem peratures below those at which either the metal or any associated gangue will fuse, eiecting, in

a non-oxidizing atmosphere and while retaining Y substantially the maximum residual heat content permissible, a. substantially complete separation of the metal in its finely divided condition from any remaining gangue, compressing the finely divided metal, in its still heated condition and in a non-oxidizing atmosphere, into a self sustaining mass, increasing the heat of said compressed mass to the welding temperature of the metal and then deforming the mass, while so heated and at a pressure that will insure structural uniformity throughout the mass, into its finished shape, said last mentioned steps being also performed while the metal is in a non-oxidizing atmosphere.

HERMAN A. BRASSERT.

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