Chimera, Timothy (127 Camelot Circle Coraopolis, PA, 15108, US)
|1.||An additive for aluminum melts comprising a compacted substantially pure iron product in particulate form.|
|2.||The additive of claim 1 wherein said iron product is a steel having an iron content of greater than or equal to about 99%.|
|3.||The additive of claim 2 wherein said steel is an atomized steel.|
|4.||The additive of claim 1 wherein said particulate form is a wafer wherein one side of said wafer is smooth and the other side of said wafer is corrugated.|
|5.||The additive of claim 3 wherein said additive is made by compacting a powdered steel in a roll press, said roll press having one smooth roller and the other roller being a corrugated roller such that the thickness of said wafer is about 1 mm at a trough and about 2 to about 3 mm at a peak.|
|6.||The additive of claim 1 wherein said particulate form has a density of about 8 g/cc to about 3 g/cc.|
|7.||The additive of claim 1 wherein said particulate form is a wafer having a thickness of about 1 mm to about 3 mm and a length and width of about 2.5 cm by about 2.5 cm.|
2. Prior Art Iron is added to aluminum melts as an essential element for thin-gauged wrought aluminum products. Typically, such iron additives take the form of iron-aluminum briquettes which comprise, for example, 70-80% iron with a remainder of aluminum. Often, a binder, such as a resin or a wax, is used to hold the briquette together.
SUMMARY OF THE INVENTION It has now been discovered that an additive which comprises a compacted, substantially pure iron product in particulate form can be used as an alloying additive for aluminum melts. The additive of the present invention is preferably substantially free and, more preferably, completely free of any binder. The iron product used to make the additive of the present invention is an iron powder that is substantially pure, 99% iron. The preferred iron product is an atomized, steel powder. The particulate form
is preferably a wafer which is smooth on one side and corrugated on the other side. It has been found that the additive of the present invention dissolves at least as rapidly in the aluminum melt than conventional briquettes but costs less to produce. The dissolution of the wafer in the aluminum melt is attributed to the shape, thickness and density of the wafer, and is especially due to the presence of the corrugated side of the wafer.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates a compacting mill and material breaker used to make the additive of the present invention; and Fig. 2 illustrates the cross-section of the additive of the present invention.
DETAILED DESCRIPTION OF THE INVENTION Preferably, the compacted, substantially pure, iron product comprises about 99% iron, and is substantially free of refractive oxides and trace elements that impart unwanted physical and chemical characteristics of the aluminum. More preferably, the iron product is a steel which is about 99% iron. Preferably the iron product is in the form of a powder. Good results have been obtained with an atomized steel powder. Preferably, the steel powder used to make the compacted additive has the following chemical analysis:
Element Percent By Weight (%) Iron (Fe) 99 (minimum) Manganese (Mn) 0.3 Chrome (Cr) 0.1 Silicon (Si) 0.05 Copper (Cu) 0.1 Nickel (Ni) 0.1 Vanadium (V) 0.05 Lead (Pb) 0.001 Cadmium (Cd) 0.001 Carbon (C) 0.05 Atomized steel powders are conventional and readily available in the marketplace. Atomized steel powders are typically made by an atomizing process where the molten steel is rapidly cooled in a powdered form.
Suitable powder used in the present invention has a particle sieve size between about 30 and about 200. More preferably, the particle size is such that about 80% of the material has a sieve size between about 60 and about 140.
Suitably, the loose powder has an apparent density of about 3 g/cc.
In order to make the additive of the present invention, the powder is compacted into a sheet and then the sheet is broken into a particulate form.
Fig. 1 illustrates a process for making the additive of
the present invention. Substantially pure powdered iron product is compacted in a compacting mill using a roll press (press roll compactor). The powder is fed into the gap between two rolls which are typically rotated at equal speeds. The feed to the roll press is substantially free and, more preferably, completely free of a binder. The size and the shape of the additive is determined by the geometry of the surfaces of the rolls. In accordance with the present invention, one roll has a smooth surface while the other roll has a corrugated surface. The output from the rolls is a sheet having one smooth side and one corrugated side. The corrugated side has troughs and peaks.
From the roll press the compacted sheet is fed to a material breaker which breaks the sheet into flakes or wafers. The product is then screened to divide the output from the material breaker by size. Oversized material is then fed to a granulator mill to break it into a feed material for the compacting mill. The oversize and undersized material are then recycled to the roll press.
Proper sized material is bagged for use and sale.
A lubricator can be used with the roll press, if necessary, however, a dryer should then be employed on the compacted material to dry the material. It is preferred that the additive of the present invention comprise about 99% by weight iron, thereby avoiding the introduction of unwanted contaminates to the aluminum melt.
Press rolls and material breakers are conventional pieces of equipment which are operated in a conventional manner in order to make the additive of the present invention. As can be appreciated, the additive of the present invention is not sintered.
The amount of pressure necessary to form the compacted additive of the present invention will vary depending on the type of powder and the type of roll press. It has been found that the compacted material is strong enough and has enough mechanical integrity to withstand handling and transportation.
Preferably, the shape of the particulate additive of the present invention is a flake or a wafer. The preferred dimensions of the wafer are about 2.5 cm by about 2.5 cm with a thickness of about 1 mm to about 3 mm. More preferably, the wafer has one smooth side and one corrugated side such that the thickness of the wafer at its trough is about 1 mm and the thickness at its peak is about 2 mm to about 3 mm.
Fig. 2 illustrates a cross-section of the additive of the present invention with its smooth side and corrugated side. The corrugated side has troughs and peaks as shown.
The density of the particulate additive of the present invention is about 8 g/cc to about 3 g/cc and, more preferably, about 7 g/cc to about 4 g/cc. Good results have been obtained with a density of about 5 g/cc. These are
It has been found that the additive of the present invention dissolves completely in an aluminum melt in about 10 minutes and that in about 5 minutes at least 50% has been dissolved.
The additive of the present invention is added to an aluminum melt as an iron alloying components, especially suited for thin gauge wrought aluminum products. The method of addition of the additive of the present invention is accomplished in a conventional manner using conventional equipment.
It will be understood that the claims are intended to cover all changes and modifications of the preferred embodiments of the invention herein chosen for the purpose of illustration which do not constitute a departure from the spirit and scope of the invention.
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