May/June 1991
Scrap suppliers and buyers use sampling and assaying to assess the quality of materials and protect their interests.
By Kent Kiser
Kent Kiser is associate editor of Scrap Processing and Recycling.
Let’s say you’re a precious metal processor and you plan to buy 10,000 pounds of circuit boards, connectors, and relays from a new supplier. How do you estimate how much precious metal is in the hodgepodge? Or, assume you’re an automobile shredder and you are selling 3,000 tons of steel scrap to an overseas client. How can you determine if the shipment meets the quality standards required by your contract with the buyer?
The answers lie in the practices of sampling and assaying. Using visual inspections, weighted averages, acid tests, spark tests, and laboratory analyses, scrap buyers and suppliers can find out what they are buying or selling--more or less. The processes are far from perfect--especially when dealing with heterogeneous scrap materials--but, for decades, sampling and assaying have served as the scrap industry’s informal insurance system for both suppliers and buyers. Many companies have also found that sampling and assaying can help them serve their customers better and market their products more effectively.
What Are Sampling and Assaying?
Though sampling and assaying are separate activities, they are always mentioned together as one process. They complement each other, and the accuracy of both can make thousands of dollars of difference on any given sale or purchase.
Sampling is the act of selecting a portion of a scrap shipment that--ideally--represents the entire load. It is usually done by an independent sampler at the supplier's facility or at a shipping location. The task is easy when a shipment is small and uniform in terms of metal type and particle size. Unfortunately, scrap shipments are often massive and rarely uniform. Charles Deak of Analytical Associates Inc. (Detroit) says wryly, "Sampling is more than a science, it's an art." Some independent samplers, in fact, refuse to practice their art on scrap, opting instead to handle ores, minerals, and alloys. "Scrap is one of the most difficult materials in the world to sample," one sampler says. "It's a whole different ball game.”
Assaying, which is done in a laboratory, "is really nothing more than establishing the composition of the metal," says Deak. "You have to do this in order to sell it, buy it, or use it." An assay scientifically analyzes the contents of a given sample, but it is the accuracy of the sample that determines how applicable the assay's results are to the entire shipment. The fact is, a good, representative sample provides the foundation on which a precise assay is based.
Unfortunately, there is no such thing as "the perfect sample." "Sampling is not magic," asserts Ron Rosenson, president of Behr Precious Metals Inc. (Rockford, Ill.) and chairman of the Institute of Scrap Recycling Industries's (ISRI) nonferrous committee. "It's a matter of probability, which means you win and you lose. It represents the best effort to take a heterogeneous mix and determine an analysis.”
How Do They Work?
To say that sampling and assaying involve many variables would be a huge understatement. The requirements and results of a sample or assay vary from shipment to shipment and material to material. A load of steel I-beams, for instance, should be easy to sample because there should be minimal variation within the pieces and within the load. No. 2 steel bundles, however, might each contain 50 pieces of metal, all different and only some accessible to the sampler.
The sample size also varies, generally increasing in proportion to the shipment's size, heterogeneousness, and particle size. As for the scope of the assaying process, it's possible to analyze for the entire periodic table of elements, says Roy Odell, vice president of Ledoux & Co. (Teaneck, N.J.).
Many large scrap loads can be analyzed through visual inspection and physical separation, precluding the need for lab assaying. Eduardo Martinez, a sampler with Inspectorate (Carson City, Calif.), says that for large shipments of shredded auto scrap, he takes a 330-pound sample out of each 1,000 tons of material. He dumps the sample onto a clean tarp and physically separates the steel from the fluff, fines, cast iron, and nonferrous metals.
A weighted average is calculated, estimating the percentage of each material in the 1,000 tons. From these findings, the steel content of the entire shipment is then estimated. If the percentage of any nonsteel material is too great, the shipment could be rejected. This test ensures that the shipment meets the quality standards outlined in the contract between the buyer and supplier.
Processors that handle precious metals and high-temperature alloys are, by necessity, the most focused on sampling and assaying. "The more valuable the material being sampled, the more care must be taken in the process," Rosenson explains.
Griff Martin, president of Martin Metals Inc. (Los Angeles), says that he takes up to a 10-percent sample from each incoming load of precious metal-bearing scrap. He processes and melts the sample, making three small metal "shots" one for his company, one for the supplier, and one "umpire" shot, which is used in the event of a dispute. This three-shot process is very common in the assaying business, particularly when dealing with precious metals.
Martin Metals's on-site lab then assays its buyer shot. The supplier can either agree to accept Martin's assay or elect to test the supplier's shot, hire an independent assayer to test it, or have a representative present at the buyer's facility during the assay.
What if the buyer and supplier get different results in their assays? Contracts often specify a "splitting limit," which states the acceptable variation that can be found between the buyer and supplier shots. The splitting limit varies from contract to contract and material to material. When discrepancies arise, the umpire shot can be assayed to determine which of the previous assays is more accurate. If the results of the umpire shot fall closer to the supplier shot, then it “wins," and vice versa for the buyer shot.
Why Make the Effort?
First and foremost, sampling and assaying guarantee that a scrap shipment meets quality standards specified in a contract, including such considerations as limits on moisture, fines, and extraneous metal content. The process is essentially an industry-created insurance system that enables suppliers to obtain the highest Price from buyers and buyers to receive the highest-quality product from suppliers. "It protects both the buyer and the seller," says Martin.
As a supplier, Barry Schuchman, president of Kasle Recycling Metallic Resources Corp. (Indianapolis), says that sampling enables his company to ensure the purity of the steel, aluminum, brass, copper, and nickel alloy it offers to its customers. "Obviously we do it to protect ourselves," he says, "but we also use it as a marketing tool. The more we can separate our product into segregated alloys, the more money we'll receive."
With precious metals, accurate sampling and assaying is essential to meet purity levels that are often measured in parts per million. "We spend more time in fine-tuning the process than anything else," Martin says, "because millions and millions of dollars are riding on it. The economies of the world are based on precious metals."
For Rosenson, sampling is a way to maximize his return while also making his customers happy. Since the prices of precious metals are dictated by the commodity exchanges, he notes, service is what differentiates firms. Sampling is a sophisticated form of customer service, Rosenson says, with "significant" costs. The expenses are necessary and worthwhile, however. "That's your whole career right there," he says. "The only way to continue the relationship is to make everybody happy."
What Kind of Investment?
How significant are the costs of sampling and assaying? When dealing with independent assaying firms, sampling can range from $50 to $100 an hour, while assaying can cost from $40 to $120 per hour, depending on the testing needed, says Deak. Since sampling is the more time-consuming process, it can cost 10 times more than assaying, he asserts.
Establishing an on-site lab can also be a significant expense. Behr Precious Metals, for example, employs two full-time chemists, owns its own spectrophotometer and atomic absorption unit, and does its own fire and wet assays. "It can cost hundreds of thousands of dollars to build and furnish a lab that can do fire and wet assays as well as instrumentation analysis,” Rosenson says.
Martin Metals also has a complete on-site lab, which accounts for 30 percent of its overall production expenses, Martin estimates. This includes the costs for lab technicians, testing instruments, and related environmental controls. "You can spend $300,000 [on equipment alone] without batting your eyes," he says. "It depends how much you want to accomplish in your lab, how sophisticated you want it, and how automated you want it." A basic lab could be set up for less than $50,000, according to Deak.
Despite the expenses, Rosenson and Martin assert that their labs are indispensable. "You may need an answer within a matter of minutes," Martin explains, which is virtually impossible to accomplish without an on-site facility. Rosenson adds, "You've got to have your own control. You can always send things out for comparison.”
Do You Need an Independent Assayer?
Most small scrap processors and recyclers, of course, do not employ a staff chemist or have elaborate on-site labs. Companies that handle material other than precious metals and high-temperature alloys have little need to invest in expensive testing equipment. Many can satisfy their testing needs through basic acid testing and spark testing. Schuchman points out another option: "If the average processing company needs something assayed, normally it can go to one of its consumers and get the scrap analyzed for free."
There may be times, however, when a processor may need to hire an independent sampling and assaying firm to assist with an overseas shipment or a particularly large, special, or heterogeneous load. Though independents are hired by one party, their purpose is to serve as an impartial body between the buyer and seller. "We're not interested in having a biased sample," says Ledoux's Odell, "otherwise we wouldn't be in business." Martin asserts that independent assayers "have to have a reputation that's so squeaky clean you can't believe it." Still, Odell points out, "We can't please both sides. Oftentimes, when we do a job, we reap displeasure."
Independents can be hired to sample and assay a shipment, or they may be called in to just sample or just assay, working in conjunction with the client or another independent firm. For instance, a processor selling titanium may have a local assaying firm do the sampling and assaying, or he may opt to have the local firm simply take a sample and send it to an out-of-state assayer that specializes in high-temperature alloys.
Independents offer various on-site services that range from visual inspections to limited chemical spot-tests to physical sampling and sorting of large shipments. Besides being an objective third party, they also offer expert representation, state-of-the-art lab facilities, and punctual work. Some independents say they can assay No. 2 copper in about 5 days, other nonferrous in 10 days, ferrous samples overnight, and precious metals in 2 days. Odell notes, however, that in today’s tight economy some processors are finding it difficult to hire an independent assayer.
Companies that don't invest in sampling and assaying, despite necessitating circumstances, can run into trouble later on, Deak asserts. "Many times they go on the basis of past experience, and that can create many kinds of problems," he says.
Independent assayers can serve as arbitrators when disputes between buyers and suppliers arise. Disputes can arise when the quality of a shipment is questioned, when the supplier contests a buyer's assay, when specifications were not spelled out clearly in advance, when market changes prompt the buyer to apply rarely used contract stipulations, and so forth. Disputes with overseas parties are not as common as domestic disputes, Deak observes, but they can be much more difficult due to the distance between the buyer and supplier. The two parties tend to settle quickly rather than initiate lawsuits, he says.
Deak, an arbitrator with the American Arbitration Association (New York City), says that assayers can help ascertain the facts of a situation and determine who is at fault and who is going to pay. He says that arbitration is faster, less expensive, and less confrontational than lawsuits. Arbitrators are also usually experts in the field, whereas judges and juries are not.
Tips to Improve Samples
The sampling and assaying process is not perfect, and both parties may not always be happy with it, but there are a few ways to avoid unnecessary problems. Rosenson advises his suppliers to make loads as uniform as possible, segregating material into separate lots by particle size, type of metal, quality of metal, and vintage. In fact, he encourages his suppliers to submit a typical sample of a load in advance so he can offer advice on the best preparation and segregation of the material. "This is an advantageous procedure for both the supplier and the buyer," he says. "You can't expect miracles. You can't send a hodgepodge and expect the results to be exactly as you anticipated." Suppliers should consider how they can improve the sampleability of each shipment, he asserts, and put themselves in the buyer's shoes, asking themselves how they would like to receive a load. Martin echoes these sentiments, saying, "You can't go to see every customer's material; it doesn't pay. So you ask the supplier to send a typical sample for evaluation and preparation suggestions."
It is just as essential for buyers to communicate openly with their suppliers regarding current concerns and potential problems, Rosenson notes. In this way, both parties can forge a more satisfying--and profitable--business relationship. "We try to communicate as much information to our suppliers as possible to alert them to possible problems and let them know what to look for," he says. "The communication between the buyer and seller is so important.”
By working together and anticipating problems, both scrap suppliers and buyers can ensure quality and protect their own interests when employing the sampling and assaying process.
Testing Nonmetallic Materials
Metals are not the only scrap materials that can benefit from testing procedures.
Paper: Scrap paper packers test their incoming stock to prevent mills from later rejecting one of their shipments. John Gold, vice president/general manager of North Shore Recycled Fibers (Salem, Mass.) and chairman of ISRI’s nonmetallic division, says that paper dealers rely on acids, applied manually with eyedroppers and spray bottles, to help them ascertain three main attributes in scrap paper:
Groundwood content. Groundwood-based paper is used mainly in newspapers and novels, while writing paper, computer paper, and other fine papers are usually groundwood-free. Groundwood-based paper turns purple when acid is applied.
Wet-strength. Wet-strength paper does not break down in water and is used commonly in beer bottle holders, coffee filters, and silicone-coated papers.
Acidity. This test is usually done on trimmings from white-envelope manufacturers.
Scrap paper processors also employ several “primitive” testing methods, such as using pencil erasers to identify certain types of inks and coatings; black magic markers and magnifiers to identify laser printing; and spit tests and tearing tests to indicate polycoated paper. Processors can also send paper samples to their mill customers for tests on ash content and ink solubility.
Plastics: In the scrap plastic industry, accurate segregation is essential to achieve high purity. A visual inspection of inbound material can be an effective first step. Most consumer plastics, such as polyethylene terephthalate soda bottles and high-density polyethylene milk jugs, can be easily identified and separated by their appearance, shape, and, increasingly, recycling identification symbols on the bottom, says Martin Forman, Forman Metal Co. and Poly-Anna Plastic Products Inc. (Milwaukee) and chairman of ISRI’s plastic committee.
If the plastic is prompt scrap from an industrial supplier, processors can often obtain a specification sheet from the supplier that will indicate the composition of the plastic. Problems can arise when the scrap plastic does not come directly from the generator or when it is in the form of durable plastic goods. Nevertheless, some of these plastics can be identified through manual tests, melt flow tests, impact tests, or flame tests, says David J. Kaplan, senior sales associate for Maine Plastics Inc. (North Chicago, Ill.). When burned, pure polyethylene, for example, has a blue flame and smells like candle wax. While an independent assaying lab may need to be hired to identify some industrial plastics, Forman, who is also president of ISRI’s Wisconsin Chapter, estimates that his company can determine the exact makeup of approximately 95 percent of its plastic scrap on its own.
Before buying certain plastic shipments, Kaplan says, processors are often able to send a sample of the material to their customers for testing, thus protecting both parties from a bad purchase. In the end, he adds, “You have to rely on the honesty of your suppliers.”
Glass: Scrap processors that accept glass rely mainly on visual inspections and careful color segregation of inbound scrap glass to maintain the necessary purity levels. Unless a company processes glass to make it furnace-ready, there is little need for more elaborate testing methods. Contamination can be avoided by knowing what to accept and diligently monitoring inbound materials. Beverage bottles (soda, beer, wine, and liquor) are acceptable, as are juice containers, ketchup bottles, and food jars. Unacceptable glass materials include light bulbs, mirror and window glass, heat-resistant ovenware, drinking glasses, crystal, ceramic cups and plates, and bottles with ceramic caps.
Vincent Pace, president of Pace Glass Inc. (Jersey City, N.J.), which produces furnace-ready glass from scrap glass, notes that contamination from unclean collection containers is a serious concern. Asphalt, dirt, and stones can cause trouble in the glassmaking process--in some cases, he says, preventing the glass from being recycled at all. In addition, contaminants can cause loads of cullet to be rejected by the buyer and, in severe cases, can lead to glass-furnace implosions, Pace explains. His company constantly promotes better separation and cleanliness to its industrial, municipal, and individual suppliers. “It’s an ongoing teaching process,” he says.
When a load of scrap glass arrives at a glass recycler such as Pace, it is first visually inspected. The glass is then dumped into a charging box and run through several mechanical processing steps and five other visual inspections. Caps, rings, and labels are removed and the glass goes through crushers and magnetic separators on its way to becoming furnace-ready.•
Scrap suppliers and buyers use sampling and assaying to assess the quality of materials and protect their interests.