Metallurgical apparatus – Process
Reexamination Certificate
1998-07-30
2001-02-13
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
C266S205000, C266S227000
Reexamination Certificate
active
06187257
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a dross removal system for removing bottom dross from a coating line. Specifically, the invention relates to a dross removal system which utilizes magnetic elements to attract magnetic dross within a molten material in order to remove the dross from the material.
BACKGROUND OF THE INVENTION
In coating applications coating lines are used to generate a molten material which is maintained in a coating pot. The molten coating material is typically zinc. In these coating lines, specifically galvanizing lines, a material known as bottom dross is often created. The dross is generated from iron placed into the coating pots wherein iron combines with the zinc to create dross. The specific weight of the alloy is approximately 10% greater than the molten zinc and therefore settles to the bottom of the coating pot or accumulates as a suspension near the bottom of the coating pot. In order to produce quality galvanized material it is necessary to periodically remove the bottom dross.
Conventional methods of removing the dross include scooping out the dross manually or using mechanical devices. While the percentage of dross present in the coating pot relative to the amount of coating zinc is small, use of the known removal devices tends to remove large amounts of the molten zinc along with the dross. The removal of the zinc results in decreased efficiency and higher expenses because of loss of coating material.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for dross removal from a coating line comprising a coating pot for holding molten material having a bottom portion at or near which dross may accumulate, and a collection device for attracting and separating the dross from the molten material, wherein the collection device includes a magnetic field inducing element.
The present invention provides a dross removal system for coating lines comprising a coating pot for holding molten metal, for example zinc. Because bottom dross is continuously being generated in the molten material due to the coating process it is necessary to remove the bottom dross in order to produce a quality galvanized material. To this end, a first embodiment of the present invention utilizes a permanent or electromagnet to attract the dross and remove it from the molten material. Because the dross is magnetic and the molten material is not, the magnet provides an excellent device for separating the dross from the molten material without also removing the molten material. The magnet is placed into the coating pot and suspended therein. The magnet attracts the dross residing at or near the bottom of the pot. The magnet is periodically removed for cleaning. Using electromagnets allows turning the magnets on and off, allowing for easier cleaning.
In another embodiment a pump is coupled to the coating pot and continuously removes a combination of molten metal and dross particles from the coating pot and passes them onto a receiving area. The receiving area may be a settling container which includes a strong magnet or magnets in its bottom. As the molten metal and dross pass through the settling container the dross settles more quickly than the molten metal because it weighs approximately 10% more. Additionally, the dross particles are drawn to the magnets, creating even more separation between the dross particles and the molten metal. The remaining molten metal is returned to the coating pot or a premelter. The receiving area may also be a trough. In that case, a magnetic drum is positioned in close proximity to the molten metal in the trough. In one embodiment the magnetic drum is positioned such that at least a portion of the drum is submerged in the molten metal-dross combination which is pumped into the trough. In another embodiment, the magnetic drum is positioned above the trough but close enough to the molten metal to magnetically extract dross particles from the molten metal-dross combination. A conveyer belt is journaled about the drum. As the dross is attracted to the drum the conveyor belt carries the dross up and out of the trough and deposits the dross into a dross container positioned adjacent to the coating pot.
In another embodiment the dross is attracted to a magnetic element and conveyed up and out of the coating pot by a conveying system. The conveying system may be a multiphase solenoid coil wound about a tube that is placed into the coating pot. A sequential electrical dc current is applied to the coil windings beginning from the bottom and working upwards. A slow travelling wave is generated inside the tube. As the wave travels, it picks up magnetic dross particles and conveys them to the top of the tube. A constantly energized electromagnet is present at the top of the tube. As the dross material is conveyed upwards it is accumulated on the magnet. The magnet is periodically cleaned to remove the collected dross. The conveying system may also be a conveyor belt having a first end positioned at or near a bottom portion of the coating pot and a second end positioned above the molten metal. In that event, a magnetic plate is positioned abutting the conveyor belt on an interior side of the conveyor belt. The magnetic plate attracts the dross. As the dross is attracted to the magnetic plate the dross contacts the conveyor belt. The conveyor belt carries the attracted dross up and out of the coating pot and deposits the dross into a dross container positioned adjacent the coating pot.
REFERENCES:
patent: 2115347 (1972-07-01), None
Derwent Abstract 1998—201804 of Japanese JP10053850A, Feb. 1998.
Derwent Abstract 1999—136940 of Japanese JP11006046A, Jan. 1999.
Fishman Oleg S.
Heine Hans G.
Inductotherm Corp.
Kastler Scott
Seidel Gonda Lavorgna & Monaco, PC
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