Today, it is nearly impossible to simply look at a piece of scrap metal to identify it correctly. Throughout the years, metal has changed significantly in chemistry and application. No longer can recyclers classify a valve as red brass simply because it’s a brass valve. Chances are that same red brass valve has been replaced by 81 metal/semired brass or in some cases replaced by a much cheaper yellow brass.
In addition to these new alloys, metals recyclers are facing heavy competition and slimmer margins. For recyclers to remain competitive, they must be able to identify various grades of scrap metal correctly.
Many scrap facilities now possess modern equipment, such as handheld analyzers or spectrometers. These tools have assisted greatly in metals identification. When identifying copper scrap, however, visual identification and magnet tests usually are sufficient (be sure to check all red metals with a magnet), but using a handheld analyzer is always a good way to remove any doubt.
What do recyclers do if they are not fortunate enough to have such analytical equipment?
The following information will assist in identifying basic grades of red metals.
Narrowing in on copper
Identifying copper scrap is relatively easy compared with identifying brass and bronze scrap. There are four primary categories of copper scrap:
- Bare bright copper wire is defined as clean, bare, uncoated, unalloyed copper wire, not smaller than No. 16 gauge wire. Bare bright also should be free of copper tubing, burnt copper wire and nonmetallics.
- No. 1 copper consists of clean, untinned, uncoated, unalloyed copper wire and cable, not smaller than No. 16 gauge. No. 1 copper also can consist of clean, unsoldered copper tubing and clean copper solids/punching. Burnt wire should be free of excess ash and nonmetallics.
- Light copper consists of miscellaneous unalloyed copper wire having a nominal 96 percent copper content. No. 2 copper should be free of excessively leaded, tinned and soldered copper wire. Burnt No. 2 copper wire should be reasonably free of ash and have no nonmetallic attachments, while No. 2 copper tubing containing soldered joints is generally accepted as No. 2 copper.
- Light copper mainly consists of miscellaneous, unalloyed copper scrap having a nominal copper content of 92 percent (minimum 88 percent). Light copper generally is considered to consist of sheet copper, gutters, downspouts, kettles and similar scrap. Light copper should be free of excessive tar, paper and other nonmetallics; check carefully for roofing nails and other contaminates.
Brass and bronze identification
Identifying brass and bronze scrap is much more difficult and detailed than identifying copper. Many of the brass and bronze grades have similar applications and uses; however, their chemistry can be significantly different. Using a handheld analyzer will assist greatly in correctly identifying the brasses.
Brasses are metals that contain zinc as the principal alloying element. Brasses also can contain other alloying elements, such as iron, aluminum, nickel and silicon.
Bronzes are copper alloys in which the major alloying element is not zinc or nickel. Originally “bronze” described alloys with tin as the only or principal alloying element. Today, the term “bronze” is generally used as a description.
When identifying brass and bronze, it is helpful to have a magnet, a bench or handheld grinder or heavy-duty steel file. Sometimes 2 percent silver nitrate is used, but this method takes a lot of use and experience to fully understand. Good lighting (such as outdoor) can assist greatly in seeing the true color of the metal.
The various brass and bonze grades recyclers will encounter include:
Red brass – The copper-tin-lead-zinc alloys comprise the most important and most widely used of all the copper-based castings alloys. In the group, recyclers will find the following families of alloys: leaded red brasses, leaded semired brasses, tin bronzes, leaded tin bronzes and high-leaded tin bronzes. Red brass is popular because of its favorable combination of casting properties, machinability and general utility. Red brass is commonly used for castings, valves, pipe fittings, water pumps, meter housings, small gears and high-quality plumbing goods.
- C83300 (92 to 94 percent copper, 1 to 2 percent tin, 1 to 2 percent lead and 2 to 6 percent zinc) is typically used in electrical hardware parts.
- C83600 (84 to 86 percent copper, 4 to 6 percent tin, 4 to 6 percent lead and 4 to 6 percent zinc) is generally used in castings, valves, fittings and high-quality plumbing goods.
- C83800 (82 to 83.8 copper, 3.3 to 4.2 percent tin, 5 to 7 percent lead and 5 to 8 percent zinc) is commonly used in general low-pressure valves, fittings and pumps.
- Seibolly Metal (87 percent copper, 6 percent tin, 0.10 percent lead, 5 percent zinc and 1.9 percent bismuth) replaces some of the lead in other red brass alloys with bismuth. Much of the new red brass is being made this way.
Red brass alloys are reddish/light yellow (medium weight) in color and have a spontaneous gray-black or black color developing on the surface when exposed to silver nitrate. They have no magnetic reaction.
Semired brass – Semired brass, called an 81 metal, is another member of the copper-tin-lead-zinc family. Alloys C84400 and C84800 are the “workhorse” alloys comprising the major tonnage of commercial plumbing fixtures, cocks, faucets and certain low-pressure valves. These alloys are popular because of their relatively low cost, good machinability and good casting properties.
- C84400 (78 to 82 percent copper, 2.3 to 3.5 percent tin, 6 to 8 percent lead and 7 to 10 percent zinc) is used in commercial plumbing fixtures, cocks, faucets and low-pressure valves.
- C84800 (75 to 77 percent copper, 2 to 3 percent tin, 5.5 to 7 percent lead and 13 to 17 zinc) is typically used in plumbing fixtures, faucets, stops and low-pressure valves.
Semired brasses are reddish/golden red but duller than red brass (because of their higher lead content). When silver nitrate is applied, it goes from clear, to gray and then rapidly changes to black. Semired brasses have no magnetic reaction.
Yellow brass – All of the leaded and high-strength yellow brass alloys contain zinc as the primary alloying element. These alloys comprise two families: the lower strength, leaded yellow brasses and the high-strength yellow brasses (manganese bronze). These alloys are used primarily because of their low cost and their good corrosion resistance and when a distinct yellow color is desired. The most common leaded yellow brass alloys are:
- C85200 (70 to 74 copper, 0.7 to 2 percent tin, 1.5 to 3.8 percent lead, with zinc making up the balance) is often used in plumbing fixtures/fittings and ornamental castings.
- C85400 (65 to 70 percent copper, 0.50 to 1.5 percent tin, 1.5 to 3.8 percent lead, with zinc making up the balance) is mostly used in plumbing fixtures/fittings and ornamental castings.
- C85700 (58 to 64 percent copper, 0.50 to 1.5 percent tin, 0.8 to 1.5 percent lead, with zinc making up the balance) is commonly used in plumbers flanges, fittings, ornamental and hardware ship trim.
Yellow brass is yellow (usually light weight) in color. Silver nitrate immediately turns black, then slowly changes to gray when exposed to yellow brass. These alloys have no magnetic reaction.
Manganese bronze – This high-strength yellow brass is another alloy considered to be in the yellow brass family. The term manganese bronze is inaccurate and somewhat confusing, however, because some alloys in the category actually contain very little manganese. These alloys find application where relatively high strength is required in combination with good corrosion resistance and moderate cost. Common members of this family are:
- C86200 (60 to 66 percent copper, 2 to 4 percent ferrous, 3 to 4.9 percent aluminum, 1 percent nickel, with zinc making up the balance) is typically used for brackets, shafts, gears and structural parts.
- C86300 (60 to 66 percent copper, 2 to 4 percent ferrous, 5 to 7.5 percent aluminum, 1 percent nickel, with zinc making up the balance) is generally used for screw down nuts, slow-speed heavy load bearings and gears.
- C86400 (56 to 62 percent copper, 0.4 to 2 percent ferrous, 0.50 to 1.5 percent aluminum, 1 percent nickel, with zinc making up the balance) is often used for strength applications, such as propellers for salt and fresh water and machine parts.
Manganese bronze is dull yellow/yellow (medium weight) in color. When exposed to manganese bronze, silver nitrate immediately turns black to gray. It reacts to a magnet but not as strongly as aluminum bronze does.
Aluminum bronze – Aluminum bronzes are copper-based alloys containing about 6 percent to 12 percent aluminum and varying amounts of iron, nickel and/or silicon. Aluminum bronzes are widely used in applications that require good strength, hardness and ductility and where corrosion resistance is required. Their bearing and wear resistance properties make them useful in applications of gears, slides, bushings, bearings, molds and dies. The nickel aluminum bronzes are used widely in saltwater applications. The most common aluminum bronze alloys are:
- C95200 (86 percent copper at minimum, 2.5 to 4 percent ferrous and 8.5 to 9.5 percent aluminum) is often used for gun mounts, slides, landing gear and marine applications.
- C95300 (86 percent copper at minimum, 0.8 to 1.5 percent ferrous and 9 to 11 percent aluminum) is often used in gears, stripper nuts, high-temp applications, mining and marine applications.
- C95400 (83 percent copper at minimum, 3 to 5 percent ferrous, 10 to 11.5 percent aluminum and 1.5 percent nickel) is used in heavy gears, nuts, pumps, landing gear and marine applications.
- C95500 (78 percent copper at a minimum, 3 to 5 percent ferrous, 10 to 11.5 percent aluminum and 3 to 5.5 percent nickel) is commonly used for extreme conditions, such as tank gun recoil mechanisms and other high-strength applications.
Aluminum bronze is light yellow on the surface and darker yellow on its fresh cut surface (brighter yellow than manganese bronze). Silver nitrate stays clear when exposed to aluminum bronze. It reacts to a magnet, with a stronger pull than manganese bronze because of its higher iron content and the possibility of nickel.
Hard brass – Hard brass, also known as leaded tin bronzes, use tin and lead to form a strong but easily machineable alloy. Hard brass is used extensively for bushings and bearings.
- C93200 (81 to 84 percent copper, 6.3 to 7.5 percent tin, 6 to 8 percent lead and 1 to 4 percent zinc) is often used in general-duty bearings and bushings. It is dull grayish/red in color and silver nitrate turns black, then gray, eventually turning black again, when exposed to this alloy. It is nonmagnetic.
This has been a brief overview of some of the basic nonferrous red metals and ways of identifying them; scrap yard will see many more alloys. Handheld analyzers are recommended for exact analysis.
The author is an account executive with Amity Metals, Charlotte, North Carolina, and can be contacted at email@example.com.