Converter Recycling: 4 Big Problems with Assay

You finally made the switch from selling your converters by the piece to selling them on assay. And you have found, like most of us have, that it is totally worth it. Your average cat sale is up 5-45% depending on how you were being treated by your buyer. 

So, with assay, what could possibly go wrong when you are selling on science and getting paid on actual metal markets?

For nearly 30 years we have been processing scrap catalytic converters for refining at United Catalyst Corporation, let me explain what can and does go wrong. And, more importantly, how you can fix it.   

Count and Weights: How many units or pounds lost is acceptable? 

In converter processing, everything begins and ends with weights and counts. The weight of your entire lot, converters, pallets, shrink wrap, and all. We begin with the end in mind. BOL weights must match. Unit counts must match what you sent in. We are a disassembly facility which means your load comes in and we destroy it. We confirm how many converters you sent in, the average value and weight of each unit. As part of our ISO certification, all our processes must be followed, and all nonconformities must be investigated and resolved before refining. Is this happening where you are processing converters? 

Dust: If you are missing weight your missing money.

If you are missing weight your missing money. But if you are missing dust, you are missing significantly more money. It is the coating of the ceramic or metallic substrate that contains the precious metals. So, the dust has the highest concentration of the platinum group metals or PGMs. The dust may be 1-3% of the weight of the load while being 10-20% of the value. Therefore, we suggest you let us de-can for you.  After the count being right, the de-canning system is paramount to getting paid the correct amount. At our plant, every shear has its own, very high-end, dust collector. Your dust is weighed and added back to your broken honeycomb or catalyst before being milled and sampled. We do not have one dust collector going to multiple shears which would break the chain of custody and leave questions as to where your dust is and who keeps it. Is this true of where you are processing converters? 

Sampling: In-house XRF, a guide, not a basis for final payment.

Did you know that when you sell on assay and refining terms that you are settling on the results of a sample of your load? It is true. After de-canning the converters, the catalyst must be milled into a powder and a representative sample must be taken to be tested. That sample is only 5-10% of your material so it had better represent all your converters. Sampling is science in and of itself. Every particle in your load must have an equal chance of being sampled and that means it must be blended properly and for enough time before it comes through the sampler and goes into the sample preparation lab. There the primary sample becomes smaller and finer and must be blended or homogenized again, and the moisture must be determined, before it is analyzed. This is just for the first analysis or XRF and it is only plus or minus 10% accurate. We do not pay you based on XRF. We have this lab and get this reading for quality control. So, we know how many ounces to expect within reason and can make an early payment determination. Do you know if you are getting paid on XRF? 

Assaying: There is no short cut to getting paid accurately.

A properly collected sample that is representative of all your converters in your load then goes through two more advanced scientific processes called pyro- and hydro- metallurgy or fire assay with chemical dissolution and an atomic absorption (AA) with an Inductively coupled plasma mass spectrometry (ICP-MS). Now your processor may have fire assay and an ICP lab in-house and pay you quickly based on the assay result they get; however, this is not the same as being paid on the assay result from the refiner or a third-party independent lab. Whose assay are you getting paid on? Can the assay be verified? 

Selling converters on assay is the way to go. It is the only way to ensure that you get paid the most from your converters with a process you can trust. You buy the car. You own the converter. The lion’s share of its value is yours. 

If you have questions about this article or any issue pertaining to the recovery of precious metals and materials from automotive recycling, we, at United Catalyst, are here to help you. United Catalyst Corporation is a processor of scrap catalytic converters that offers global refining services. Our recycling solutions are accurate, scientific, and verifiable to get you the most money. United Catalyst is a processor you can trust.

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Becky Berube serves the recycling community as President of United Catalyst Corporation, Co-Chair of the Automotive Recycling Association’s Events Advisory Committee, and is an ExCom Board Member of the International Precious Metals Institute. She can be reached at 864-834-2003 or by email at