US3414408A - Briquetting process - Google Patents

Description

United States Patent 3,414,408 BRIQUETTING PROCESS Walter W. Eichenberger, 2615 W. th St., Erie, Pa. 16505 No Drawing. Continuation-impart of application Ser. No.

309,329, Sept. 16, 1963. This application May 17, 1966,

Ser. No. 550,623

3 Claims. (Cl. 75-214) ABSTRACT OF THE DISCLOSURE Disclosed herein is a process of manufacturing briquettes for use in metallurgical products as an alloying agent. The material to be briquetted is enclosed in a container made of material that is compatible with the metallurgical process. The containers are provided with holes so that any liquid that may be entrained on the material can escape from the holes when the container with the material in it is pressed in a briquetting press. The containers are strong enough to hold the material when briquetted in integral body.

This is a continuation in part of patent application, Ser. No. 309,329, filed Sept. 16, 1963, now abandoned.

It is common practice to briquette titanium turnings by adding a soft matrix material such as titanium sponge to the turnings and compressing them in a briquetting press. This requires the utilization of the matrix material and it is sometimes inconvenient and expensive to carry out the process.

It has been discovered that by putting the titanium turnings in a can such as an aluminum can having sufiicient strength to hold the briquette together after pressing and compressing the can in a briquetting press, such compression causes the can to hold its shape and a perfect briquette results.

When cans made of aluminum are used, the aluminum can filled with titanium and titanium alloy turnings is compatible with the alloys. The aluminum forms part of a common alloy which is six percent aluminum, four percent vanadium, and ninety percent titanium.

The container is not only given a permanent set during the briquetting operation but it is work-hardened during the process so that it holds the briquette in shape, thus eliminating the necessity of a binder in the titanium.

Certain high alloy turnings and borings and most of the SAE 300 and 400 series of stainless steels are exceedingly difiicult to briquette in the as-is condition because of the high strengths of these materials which is further increased even higher by the fact that these turnings and borings are work hardened in the machining process and sometimes, due to high machining speeds and feeds they are even air quenched. In many cases, the only way that these superalloy turnings and borings can be briquetted is by annealing them first. But, annealing is expensive and, unless the annealing is done in a controlled or inert atmosphere, loss of value of the alloys contained can occur through oxidation. One theoretical aspect of briquettability of a material is that the briquetting pressure exerted on the material being briquetted (usually rated in tons p.s.i.) should be great enough to permanently deform the material thus giving it a permanent set. In the case of these superalloys and the stainless grades, this would mean that unit pressures of higher than 50 tons p.s.i. on the material would have to be used in order to make coherent briquettes. This can be done, but it then calls for expensive high tonnage rated hydraulic presses. The reason for wanting to briquette these materials in the first place is to be able to remelt them for the primary ice purpose of recovery of the costly alloy content, i.e. nickel, chromium, cobalt, tungsten, molybdenum, vanadium, titanium, zirconium, tantalum, etc. If these superalloy turnings and borings are charged for remelting into any type of furnace except a vacuum furnace, there occurs a considerable oxidation loss due to the high amount of surface presented by these borings and turnings to the furnace atmosphere. By briquetting, these turnings and borings are compacted into a dense mass which melts much as would a solid heavy mass. During melting, there is a normal formation of an oxide film or crust completely surrounding the mass being melted. Once formed, this oxide film or crust acts as a protective layer preventing further oxidation of the metal surrounded by that film or crust. As the individual pieces in the furnace melt, they coalesce with the molten unoxidized metal forming the bath while the oxide film or crust forms the slag which further protects the bath metal from further oxidation loss. This is why it is beneficial to briquette turnings and borings.

One other benefit of briquettin is that it provides easier and faster charging and also faster melting to have briquettes instead of uncompacted, loose turnings and borings.

The idea of using this can method of briquetting provides an economical method of briquetting the superalloy turnings and borings by having the can original container act as an external binder to make a coherent compact. It is possible to briquette these superalloy turnings and borings by mixing a binder with them and then briquetting at ordinary briquetting pressures, but the use of an admixed binder always creates the problem of contamination of the metal by the chemical constituents of the binder. The composition of the can used in this can method must be compatible with the chemistry of the metal being briquetted and subsequently remelted. Most of these superalloys have iron (Fe) as one of their components and the addition of additional iron (Fe) from the material of the can used is not significant enough to cause this additional (Fe) to be considered as a contaminant. Also, where the tin plate of the can is considered as a contaminant, even though the tin will volatilize and not enter wholly into the melt, the cans used can be of unplated black steel to eliminate any possibility of tin pick-up in the melt. Further, the can used need not be of steel at all; it may be made of nickel sheet or strip, aluminum, titanium, etc., anything that is compatible with the contained turnings and borings. Also, the can used should be of sufiicient thickness, for example, .025" to .010, so that it does act as a binder (external) in the finished can. However, even thin sheet or strip makes a satisfactory final product because during the briquetting of the can, the can itself is compressed and deformed permanently and actually work hardened which strengthens the final can. The external binder, which is the compressed and deformed can container, being of a lower melting point than the contained turnings and borings, will melt first and, as it melts, some of it becomes oxidized and this external melting and partial oxidation of the can forms a protective layer surrounding the contained turnings and borings. By the time the outside can layer has melted, the inside contents of the turnings and borings have been heated sufficiently so that they are annealed or softened. Thus, any possible sprin-giness of the contained turnings and borings is rendered non-harmful. If the external binder is of a material of a higher melting point than the contained material, this offers no problem since then the contained material will be protected from oxidation by the higher melting point can, but the melting points of the can container and the contained material should be fairly close to each other.

This can method can also be used in making an alloy addition to a molten metal, such as liquid steel, for example. This is an altogether different application than the melting operation previously covered. It is becoming more popular these days, due to development of rapid melting operations, such as B.O. F. furnace, oxygen lanced open hearth furnace, etc., to add alloying agents to the ladle as the furnace is being tapped rather than to the bath metal in the furnace after it has been refined or worked to the desired end point. The reason for adding alloys to the ladle is that this method is faster and better alloy recovery is obtained this way. When alloy additions, in particular, ferromanganese, ferrosilicon, ferrochrome, are added to the ladle in the lump form, there is always the possibility of segregation occurring due to the incomplete melting and distribution of these lumps of the various ferroalloys.

There is far less chance of segregation occurring if these ferroalloys are added to the bath metal in the furnace since it is usual practice to hold the furnace on heat for a time after making the ferroalloy additions in order to insure their complete melting. As the heat is tapped into the ladle, mixing occurs which further minimizes the possibility of segregation; but there is a higher loss of the alloy component due to increased oxidation loss. If the ferroalloys which are to be added are added to the ladle or to the tapping stream as fines in order to insure that they melt quickly, there is a considerable loss of these fines by the mechanical elevation of the fines with the hot air current which is present as the hot metal, approximately 3000 Fahrenheit, is tapped into the ladle. This phenomenon can be called a convection current loss. The fines are carried away to a considerable extent by this convection of hot air. By taking these ferroalloys as fines and putting them into a can, they can now be added to the ladle or to the tapping stream in the same manner as a lump. Thus, they are carried into the ladle metal as a lump, but once the can is surrounded by the liquid molten metal, a thermal shock occurs causing the can to pop open sending its contents of fines into the ladle metal. Thus, maximum efficiency of the fines can be obtained.

The third application of the disclosed method is totally different from the second (alloy addition) purpose but allied to the first purpose (melting). It is the briquetting of excessively wet (any type of liquid, such as water, mineral, or synthetic oil, etc.) borings (cast-iron borings, in particular) or turnings. When attempting to briquette such wet materials, especially if the borings and turnings are fine particles, the liquid content is trapped within the briquette and the net effect is that you are attempting to compress a liquid. 'If the material being briquetted is coarse, a considerable portion of the liquid content may be squeezed out during the briquetting process, but some of it will always remain.

This liquid problem becomes more acute when dealing with fine powders, filter cakes, etc. Further, if the liquid present is an oil type of liquid, this oil will act as a lubricant between the grains or particles of the material being briquetted and will result in a weak briquette which cannot be handled mechanically without excessive breakage. Borings, turnings and fines are referred to herein as swarf.

In order to briquette such wet materials, without having to first dry them by some preliminary means, the can method disclosed is used with a slight variation. After the can is filled with the material to be briquetted, the ends and body of the can are punctured with small pin holes. The can may be punctured with these small pin holes before being filled with the material to be briquetted. Either before or after filling is satisfactory. Then the can is briquetted. After being briquetted, the liquid contained in the material is forced (by the internal stress of compaction) out of these pin holes. It weeps out of these pin holes. Without the external can binder, the same weeping would occur momentarily at the instant that the briquette is removed or stripped from the briquetting die, but there also would occur at the same moment a slight expansion of the briquette which causes it to act as a sponge, pulling the liquid back into the briquette. The external can binder prohibits this re-expansion of the briquette from happening. Therefore, there is only one way for the liquid to go, out of the pin holes in the can.

A 4th application is for the manufacture of symmetrical parts, as in powder metallurgy, a flywheel may be made by putting the can of materials in a die of proper shape, and compressing same.

The advantages in using the disclosed method are as follows:

(a) Lower than normal briquetting pressures can be used since the can acts as an external binder.

(b) The wear on the briquetting tools is lessened since the abrasive surface of the material being briquetted does not contact the briquetting tools. The can makes the contact.

(c) Because lower than normal briquetting pressures can be used, the productivity of the press is increased.

((1) Because lower than normal briquetting pressures can be used, press maintenance cost is lower.

(e) Cleaner press operation all around is provided.

It is, accordingly, an object of the present invention to provide an improved briquetting process.

Another object of the invention is to provide an improved briquette.

A further object of the invention is to provide a briquette which is simple in structure, economical to manufacture, and efficient for its purpose.

Another object is to provide a briquette made from wet material held together by a perforated can.

The above objects and others which may be later referred to, together with others apparent to those skilled in the art, may be attained by carrying out the invention in the manner hereinafter described in detail.

To carry out the process disclosed herein, the titanium turnings are first crushed to compact them before they are put into the container. The container with its contents is then put in a briquetting press and pressed. Cans three inches in diameter to six inches in diameter have been found to be suitable for containers for use in this operation. These sizes are stated for purposes of example only. Any convenient size of container can be used.

Examples of the process disclosed herein are as follows:

EXAMPLE A 1.-crush titanium turnings to reduce the particle size 2.provide aluminum cans of approximately one quart volume and .010" thick 3.fill said cans with said turnings 4.compress the can and turnings in a briquette press.

EXAMPLE B 1.crush titanium turnings 2.provide a steel can .015" thick 3.-fill the can with said turnings 4.compress the can and turnings in a briquetting press.

EXAMPLE C l.-provide cast iron borings wet with a liquid 2.provide a can of a metallurgically compatible material having relatively small holes therein having sufiicient strength to hold said borings in briquette form when pressed 3.-fill said cans with said wet borings 4.compress said borings in a briquetting press.

EXAMPLE D 1.provide sponge borings 2.provide a can 3.-fill said can with said borings 4.provide a die of the shape of an article of manufacture 5.-place the can in the die and press to the shape of the article.

EXAMPLE E 1.-provide sponge iron borings 2.provide a can having small holes therein 3.-fill said can with wet borings 4.-provide a die of the shape of an article of manufacture 5.-place the can in the die and press to the shape of the article.

This process can also be carried out on stainless steel turnings of the SAE 300 series; i.e., 18-8 stainless steel. It is well known that aluminum, stainless steel, and many other metals harden and obtain resiliency when coldworked.- Cold-working characteristics which enable the metals to harden and obtain resiliency have to do with loss of ductility as opposed to elasticity and obtaining resiliency has to do with an increase in resiliency, Thus, the can will tend to hold the shape into which it is compressed.

The foregoing specification sets forth the invention in its preferred practical forms but the method described is capable of modification within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined 'as follows:

1.'A process of briquetting comprising placing swarf wet, with a liquid in a container:

said container being made of bendable material and having sufiicient strength and rigidity to retain a shape into which it is bent,

compressing said container with said swarf therein to a size substantially less than the uncompressed size of said container in the tools of a briquetting press, thereby forming an integral briquette held together by said container,

said container having perforations therein whereby said liquid in said swarf escapes when said swarf is pressed.

2. The process recited in claim 1 wherein:

said container is made of a material having suflicient strength to hold said swarf in substantially the same shape to which it is pressed -by said briquetting press and tools.

3. The process recited in claim 2 wherein:

said material is at least ten one thousandths of an inch thick.

References Cited UNITED STATES PATENTS 2,725,288 11/1955 Dodds 75-226 2,783,504 3/1957 Hamjian 75-214 X 2,792,302 5/1957 Mott 75-214 2,943,933 7/1960 Lenhart 75-214 3,050,386 8/1962 Von Dohren 75-222 X 3,269,826 8/ 1966 Bu-mgarner 29-420 X 3,071,463 6/1963 Hausner 75-213 X FOREIGN PATENTS 689,758 6/ 1964 Canada. 758,545 10/ 1956 Great Britain. 925,142 5/ 1963 Great Britain.

BENJAMIN R. PADGETT, Primary Examiner.

A. J. STEINER, Assistant Examiner.