Specialized metallurgical processes – compositions for use therei – Processes – Process control responsive to sensed condition
Reexamination Certificate
2001-08-31
2002-11-12
Andrews, Melvyn (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Process control responsive to sensed condition
C075S638000
Reexamination Certificate
active
06478847
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the recycling and processing of scrap copper, and more particularly to a new and improved copper scrap processing system that optimizes the feedstock selection ratios of various sources of relatively inexpensive copper scrap feedstocks in order to more efficiently produce a recycled copper product having pre-determined acceptable levels of various contaminants.
BACKGROUND OF THE INVENTION
Within most metal fabrication industries, a key component of the manufacturing processes is the recycling of scrap metal for use as a raw feedstock material. Scrap metal is often collected and melted down for use in manufacturing new metal products. The ability to recycle scrap metal efficiently is a key objective in any metal recycling operation. Within an metal casting and refining operation, it is desirable to produce a metal that is as free of impurities as possible. Impurities, or contaminants as they are also known, are those constituents that exist in some or all of the scrap feedstock. The metal manufacturer seeks to minimize the amount of impurities in its final product.
Within the copper manufacturing industry, most standards for products employing copper require a purity content of at least 99.9 weight percent copper. If the scrap copper feedstock used in producing a final metal product is less than 99.9 weight percent copper, then such scrap must be blended with a more pure copper feedstock in the initial melting process, and possibly further refined after that, in order to produce a final metal product that is 99.9 weight percent pure copper. Pure copper cathode, which is 99.99 weight percent pure copper, is often used to blend with, and dilute, the impurities contained in scrap feedstock.
Copper scrap typically falls into one of the following generally recognized exemplary categories: No. 1 heavy scrap copper which consists of clean unalloyed copper solids and must be uncoated; No. 2 heavy scrap copper which consists of clean unalloyed copper solids that can be coated; soldered copper pipe which consists of assorted copper pipe (of any length) with soldered joints or ends, which are free of brass or bronze or non-copper fittings; beryllium copper which consists of clean beryllium alloyed copper solids, and may contain clippings, punchings, bar or pipe, tubing, and elbows; light copper scrap which consists of miscellaneous, unalloyed copper solids; copper turnings which consist of unalloyed copper turnings, grindings, or borings, which may be contaminated with cutting oils; No. 1 bare bright copper wire which consists of bare, uncoated, unalloyed copper wire, not smaller than 16 gauge; No. 1 copper wire which consists of clean, uncoated, unalloyed copper wire, not smaller than 16 gauge; No. 2 copper wire. which consists of clean, unalloyed copper wire, free of hair wire, brittle burnt wire, and excessive oils; No. 1 copper wire nodules which consist of No. 1 bare, uncoated, unalloyed copper wire nodules, from a chopping or shredding operation, not smaller than 16 gauge; No. 2 copper wire nodules which consist of No. 2 unalloyed copper wire nodules, from a chopping or shredding operation; No. 1 insulated copper wire which consists of plastic insulated, unalloyed, uncoated (plated) copper wire, not smaller than 16 gauge; No. 2 insulated copper wire which consists of assorted plastic insulated, unalloyed copper wire, free of heavy or double insulation; No. 3 insulated copper wire which consists of assorted plastic insulated, unalloyed copper wire, including heavy or double insulation, and plastic insulated telephone cable; and so forth.
It should be noted that not every copper scrap recycling operator uses all of the afore-mentioned categories of copper scrap; however, most copper scrap recycling operators typically use one or more of the afore-mentioned categories of copper scrap during the course of routine recycling operations.
The scrap can be in many different forms, such as it's original configuration, or it can be physically altered by compacting, baling, shredding, granulating, and the like. When copper scrap arrives at a recycling facility, it is first physically segregated into the afore-mentioned individual categories. Each category of scrap is then analyzed to determine the chemical composition thereof. Typically this is done by taking a small sample of each category of scrap, melting it, and then running the sample through one or more diagnostic instruments that can detect the presence and amount of different metallic elements. In this manner, the copper scrap recycling facility operator can quickly determine the relative quality of the particular category of copper scrap. If a particular category of scrap falls below a pre-established quality threshold (e.g., has a very high contaminant level), it is typically returned to the seller.
A complicating problem encountered by many copper scrap recycling operators is that each category of copper scrap typically contains one or more contaminants, at various levels, that need to be taken into account as to how they might impact the quality control and the sale price of the recycled copper product.
For example, impurities such as zinc (Zn), tin (Sn), lead (Pb), iron (Fe), and aluminum (Al) are of particular interest. Additionally, impurities such as antimony (Sb), arsenic (As), nickel (Ni), bismuth (Bi), cadmium (Cd), phosphorous (P), silicon (Si), sulfur (S), tellurium (Te), silver (Ag), chromium (Cr), magnesium (Mg), selenium (Se), zirconium (Zr), manganese (Mn), cobalt (Co), gold (Au), and beryllium (Be), as well as others, are also of interest. It should be noted that not every one of the afore-mentioned contaminants is present in any given grade of copper scrap; however, most grades of copper scrap will typically have one or more of the afore-mentioned contaminants present in various weight percentages.
Unfortunately, conventional copper scrap recycling operators typically combine the various sources of copper scrap together in a haphazard and poorly planned manner. The resulting recycled copper product is typically high in one or more contaminants. The recycled copper product must then be either further refined (which is very time consuming and expensive) or sold at a lower price than the operator had anticipated.
Although this problem can be improved by using copper cathode (which has very low levels of contaminants) as a feedstock source, the use of copper cathode exclusively is not economically feasible for most copper recyclers. Therefore, the problem of contaminants must eventually be addressed.
There are two primary approaches that can be used to control contaminant levels in the recycled scrap product. First, copper scrap feedstocks having relatively low levels of contaminants can be used. However, these feedstocks tend to be relatively expensive, albeit not as expensive as copper cathode, but more expensive than lesser grades of copper scrap feedstock.
Second, copper scrap feedstocks having relatively high levels of contaminants can be used. However, it is then typically necessary to combine them with relatively high grade copper, such as copper cathode, to produce a recycled product having acceptable contaminant levels. Therefore, the cost savings attempted by using the relatively low grade copper scrap feedstocks are offset by having to supplement with relatively high grade copper to control the contaminant levels. Even if it were possible to use relatively low grade copper scrap feedstocks without resorting to supplementation with relatively high grade copper, it would typically still be necessary to refine the recycled copper to remove or lessen the amount of certain contaminants (e.g., tin, lead). This is due to the fact that most copper recyclers do not employ any significant quality controls on the selection and ratios of the relatively low grade copper scrap feedstocks that are being used. Refining is an expensive process that adds to the production costs of the resulting recycled copper product, thus offsetting any material cost savin
Babin Paul D.
Dennis Glenn
Jamison Tommy
Popetz Allen
Andrews Melvyn
Harness & Dickey & Pierce P.L.C.
Mueller Industries, Inc.
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