RECYCLED ALUMINUM ROD

Abstract

A rod made of recycled aluminum that can be used to deoxidize steel during the refining process is the subject of this application. The method of producing such recycled aluminum rod is also explained.

Description

CROSS REFERENCE TO RELATED APPLICATION

The present patent application is based upon and claims the benefit of provisional patent application No. 62/712,564 filed on Jul. 31, 2018.

BACKGROUND OF THE INVENTION

The invention is directed to a rod made of recycled aluminum that can be utilized to change the properties of steel that is being refined. Aluminum has been added to molten steel for many years to deoxidize the steel during the refining process. The amount of aluminum added to the molten steel is controlled to produce a steel with desired characteristics or properties. Traditionally, only aluminum rods made of newly refined high aluminum content could be used to deoxidize the molten steel. Such rods are expensive, as it is necessary to refine bauxite ore to produce the high-quality aluminum rods that could be processed in the steel manufacturing equipment. Such aluminum rods are usually referred to as primary aluminum rods. In addition, the primary aluminum rods have a stiffness and melting temperature that are low enough that such rods melt and spread out on the top portion of the molten steel. This results in a poor distribution of the aluminum in the molten steel and usually necessitates the addition of a mixing process to adequately distribute the aluminum to deoxidize the molten steel. The current invention details the use of recycled aluminum, which greatly reduces the cost of the aluminum rod that is utilized in the steel refining process.

The objectives and advantages of the invention will be more readily understood from reading the following specification in connection with the accoupling drawings.

SUMMARY OF THE INVENTION

A rod made of recycled aluminum that can be used to deoxidize steel during the refining process is the subject of this application. The method of producing such recycled aluminum rod is also explained.

IN THE DRAWINGS

FIG. 1 is a side elevational view of the process for making the recycled aluminum rod.

FIG. 2 is a side elevational view of the annealing aluminum rod.

FIG. 3 is a side elevational view of the recycled aluminum rod used to deoxidized molten steel.

FIG. 4 is a flow diagram of the steps used to make the recycled aluminum rod.

DESCRIPTION OF THE INVENTION

The invention is directed to an aluminum rod that can be utilized to deoxidize steel during the refining process. More particularly, the aluminum rod is made from recycled aluminum which significantly reduces the cost of the aluminum rod utilized in the steel refining process. The aluminum rod is annealed under very precise conditions to reduce the stiffness of the aluminum rod so that it can be effectively utilized in the steel refining process. The features of the invention will be more readily understood by referring to the attached drawings in connection with the following description.

Scrap aluminum 5 from a variety of sources is placed into a vessel 9. The vessel 9 is designed so that the vessel can heat the scrap aluminum to a temperature that is above the melting point for the scrap aluminum. The vessel is usually a reverb or reverberating furnace that can heat the scrap aluminum above the melting point of the aluminum. During the process where the scrap aluminum is melted in the vessel, essentially all of the magnesium in the scrap aluminum is removed. A chlorine gas is introduced into the vessel 9 while the scrap aluminum is being melted and the chlorine gas burns off the magnesium. After the magnesium has been removed from the scrap aluminum the material in the vessel 9 will be at least 95% aluminum with the remaining 5% of the molten material comprised of other components.

Once the magnesium has been removed from the scrap aluminum and the scrap aluminum has been heated to a molten state, the aluminum is formed into a rod by process 12, which is described in a flow diagram in FIG. 4. In the process, the molten scrap aluminum is fed from the vessel 9 through a heated launder or trough 61 into a degasser 71. The launder has heated lids 63 that enclose the launder. The heated lids are maintained at a temperature that keeps the molten scrap aluminum at a desired temperature. The heated lids 63 reduce temperature variables in the process and allows the molten scrap aluminum to be more easily processed into a rod. The molten scrap aluminum passes through a degasser 71, the degasser removes hydrogen gas from the molten aluminum. The removal of the hydrogen gas from the molten aluminum improves the grain structure and increases the density of the molten aluminum. The degasser improves the stability of the molten aluminum and makes it easier to process the molten aluminum into a rod with the desired properties. From the degasser the molten aluminum is fed into a casting machine 11 where at least one forming roller 15 forms the molten aluminum into a cylindrical rod. As the molten aluminum moves through the at least one forming roller 15, the temperature of the aluminum rod drops below its melting point so that the aluminum will stay in the cylindrical form created as the aluminum passes through the at least one forming roller. A bar prep unit 17 can also be utilized to help shape the aluminum into a cylindrical shape. The newly formed aluminum rod is advanced from the at least one forming roller 15 for a distance in a location at an atmospheric temperature to sufficiently cool the aluminum rod so that the rod will retain the shape created by the at least one roller. The cylindrical rod that leaves the bar prep unit 17 is usually not in the final size or diameter that is needed for future use in refining steel. Accordingly, the cylindrical rod, made of recycled aluminum, is passed through a heater 18 where the temperature of the rod increased or elevated to assist in further processing for the rod. From the heater the rod is directed through a mill stand 20 where a plurality of rollers act upon the rod to progressively decrease the diameter of the rod to a desired size. Usually there are from about 3 to about 9 rollers that are in the mill stand for sizing the aluminum rod to the desired diameter. Once the aluminum rod leaves the mill stand, the rod passes through a quench line 23 where the temperature of the rod is reduced to essentially atmospheric temperature. Usually, water is sprayed on the rod in the quench line to reduce the temperature of the rod in an efficient and quick manner. From the quench line 23, the rod is directed to a diverter 24 where the rod is coiled around a spool 21. Once the desired quantity of rod is coiled around the spool, the rod is cut, and the diverter directs the rod 19 to a different spool so that the rod can be coiled around the next spool in an essentially continuous manner.

The aluminum rod 19 on the spool 21 is next positioned in a furnace 25 where the aluminum rod is heated to a temperature that is close to the melting temperature of aluminum. Usually several spools of aluminum rods are positioned in the furnace at the same time to increase the efficiency of the heating process. The elevated temperature in the furnace is used to bring the aluminum rod up to a temperature from about 1000° F. to about 1200° F. with the preferred range for the temperature of the aluminum rod being from about 1100° F. to about 1150° F. The aluminum rod in the furnace 25 will be maintained at the elevated temperature from about 2 hours to about 5 hours with a preferred range being from about 3 hours to about 4 hours. In some applications, it has been found to be preferable to tower the annealing temperature to about 800° F. to about 900° F. and to extent the time the aluminum rod is held at this temperature to about 4 to 5 hours. The lower temperature and longer retention time produce an acceptable aluminum rod with desired tensile strength. Subjecting the aluminum rod on the spool 21 to these elevated temperatures in the furnace for this period of time will effectively anneal the aluminum rod and effectively reduce the stiffness of the aluminum rod and increase the ductility of the aluminum rod. Once the annealing period is over, the aluminum rod will be removed from the furnace 25, allowed to cool and be available for further processing. The aluminum rod 19 on the spool 21, after annealing, has a stiffness from about 30.000 to about 35,000 KSI and a melting temperature from about 1220° F. to about 1250° F. The aluminum rod before annealing has a stiffness of approximately from about 31,000 to about 42,000 KSI and an aluminum rod with this level of stiffness has a reduced flexibility that can make it difficult to utilize such an unannealed aluminum rod in further applications. An aluminum rod made of primary aluminum, without using recycled aluminum, has a stiffness from about 18,000 to about 23,000 KSI and a melting temperature from about 1180° F. to about 1200° F.

The annealed aluminum rod 19 on the spool 21 is posited adjacent a steel refining furnace 31 so that the aluminum rod can be used to deoxidize the steel that is being produced. The aluminum rod 19 is advanced from the spool 21, through a guide 35, around a guide roller 37 and around and idler roller 39. From the idler roller the aluminum rod 19 is advanced between a plurality of drive rollers 43. The drive rollers engage the aluminum rod and cause the aluminum rod to be advanced in a direction away from the idler roll 39. This advancement also causes the aluminum rod to be advanced from the spool 21 through the guide 35 over the guide roller 37 and around the idler roll 39. From the drive rollers 43 the aluminum rod is advanced through a chute 47 which directs the aluminum rod towards the steel refining furnace 31. The aluminum rod 19 exits the chute 47 and enters the steel refining furnace 31 where the aluminum rod comes into contact with the molten steel in the steel refining furnace. The drive rollers 43 are caused to rotate by a drive mechanism 45. The drive mechanism is designed so that the rotation of the drive rollers 43 can be precisely controlled to allow a desired quantity or length of the aluminum rod to be introduced into the molten steel in the steel refining furnace 31. Once the desired quantity of the aluminum rod has been fed into the molten steel, the drive rollers are stopped. A cutting mechanism 51, an optional feature, can be positioned in the chute 47 for cutting the aluminum rod 19 once the desired length of the aluminum rod has been fed into the molten steel 33 in the steel refining furnace 31. The length of the steel rod 19 advanced into the steel refining furnace 31 is calculated so that the aluminum rod will effectively deoxidize the molten steel 33 that is being produced in the steel refining furnace 31. The stiffness and high melting temperature of the recycled aluminum rod 19 allows the rod to advance a greater distance into the molten steel before the rod melts than a rod made with primary aluminum. The deeper penetration of the aluminum rod 19 into the molten steel provides a better distribution of the aluminum in the steel batch and increases the effectiveness of the aluminum rod in deoxidizing the molten steel. The better distribution of the aluminum using the recycled aluminum rod produces steel with the desired properties with less processing required. The properties of the molten steel in the steel refining furnaces can be monitored, and this allows additional lengths of the aluminum rod to be advanced and positioned into the molten steel until the molten steel has the desired properties for the end use applications that are planned for the finished steel produced by the steel refining furnace. Depending on the arrangement of the feeding mechanism for the aluminum rod 19, the stiffness of the rod can be adjusted to allow for the stiffest rod that can be fed into the molten steel. The stiffness of the rod is adjusted by adjusting the temperature and duration of the annealing process for the rod 19. The stiffest rod that can be effectively used is preferred.

The above detailed description of the present invention is given for explanatory purposes. It will be apparent to those skilled in the art that numerous changes and modifications can be made without departing from the scope of the invention. Accordingly, the whole of the foregoing description is to be construed in an illustrative and not a limitative sense, the scope of the invention being defined solely by the appended claims.

Claims

1. A rod for use in steel refining comprising:

a rod being composed of recycled material having at least 92% by weight of aluminum and having no more than 5% by weight of any other component; and

the rod having a stiffness from about 30,000 to about 32,000 KSI.

2. The rod of claim 1 wherein the rod has been subjected to an elevated temperature of at least 1,000° F. for at least 2 hours.

3. The rod of claim 1 wherein the rod has at least 94% by weight of aluminum.

4. The rod of claim 2 wherein the rod has been subjected to an elevated temperature from about 1100° F. to about 1150° F. for a time period from about 3 to about 4 hours.

5. The rod of claim 1 wherein the rod has been subjected to an elevated temperature of about 800° F. to about 850° F. for a time of about 4 hours to about 5 hours.

6. The method of forming a rod used in steel refining comprising:

heating scrap aluminum in a furnace to a temperature above the melting point for the scrap aluminum;

introducing chlorine gas into the furnace to where the scrap aluminum is being heated, the chlorine gas removing magnesium from the scrap aluminum;

forming the heated scrap aluminum removed from the furnace into a rod by passing the scrap aluminum through at least one forming roller;

quenching the rod produced by the at least one forming roller to reduce the temperature of the scrap aluminum rod;

winding the quenched scrap aluminum rod on a spool;

heating the scrap aluminum rod on the spool to a temperature slightly below the melting point of the scrap aluminum for a period of time to anneal the scrap aluminum rod.

7. the method of claim 6 in which the scrap aluminum rod on the spool is heated to a temperate of at least 1000° F. for at least 2 hours.

8. The method of claim 7 in which the scrap aluminum rod on the spool is heated to about 1100° F. to about 1150° F. for a time period from about 3 to about 4 hours.

9. The method of claim 6 in which the scrap aluminum rod on the spool is heated to a temperature of at least 800° F. for at least 4 hours.

10. The method of claim 6 in which hydrogen gas is removed from the molten scrap aluminum by passing the molten scrap aluminum through a degasser prior to forming the molten scrap aluminum into a rod.

11. The method of claim 6 in which the temperature of the molten scrap aluminum is maintained at a desired temperature by passing the molten scrap aluminum from the furnace through a heated launder.

12. The method of claim 11 in which the launder has heated lids that function to enclose the launder and assist in maintaining the molten scrap aluminum at a desired temperature.