How Many Stages are There in the Catalytic Converter Recycling Process?

converter processing stages

To ensure the proper recovery of platinum, palladium, and rhodium from recycled catalytic converters, they have to be toll-refined. This is a complicated process that involves multiple steps to extract the Platinum Group Metals (PGMs) contained within, and for many recyclers, the toll-refining process remains a mystery. We’re here to shed some light on the entire process, from converter acquisition to the sale of your precious metals.

Acquiring Your Converters

The first step in the recycling process is acquiring catalytic converters. Recyclers collect converters by buying cores, processing end-of-life vehicles, buying scrap metal, and many more ways.

Most recyclers use price lists or pricing tools to help them acquire material profitably. For example, automotive recyclers who partner with PMR use VIN/TRIM. With this tool, they receive quick converter estimations at auction with the vehicle VINs or year, make, and model. They can then adjust their bidding price and make sure that they collect material profitably.

Once you’ve collected enough converters, you can sell them. But remember, no matter who you sell to, your converters will eventually end up at a toll-refining facility.

The Toll-Refining Process

Toll-refining converters is the only way to extract the precious metals that they contain. Here’s how the process works.


After a toll refiner receives your converters, the units are counted or graded. This is an important step because processors will use the grading report for comparison once the assay is complete. But we’ll get to that later!

During grading, processors look for total units, unit fullness, and material types (DPFs, OEMs, Aftermarkets, foil, etc).


Once your converters have been counted, they are decanned. This means any pipes, shields, and metal shells are removed. The dust produced during this stage often has twice the concentration of precious metals, so capturing any dust is the most important part of this step. It’s important that your processor has the proper equipment and methods to capture dust effectively, because dust is money!

Crushing & Milling

When decanning is complete, the loose ceramic is crushed, milled, and commingled. The result is a homogenous powder with equal particle size, which means each particle has an equal chance of being analyzed. Once the crushing and milling phase is over, multiple samples are taken for laboratory analysis.


A laboratory assay is the only possible method to determine the composition of precious metal content in your converters. A proper analysis uses both the X-ray Fluorescence (XRF) and Inductive Coupled Plasma (ICP) methods to determine precious metal content.

X-ray Fluorescence

XRF is the most common method used in assay laboratories. XRF is a non-destructive technique that measures fluorescent secondary x-rays emitted by a sample.

It’s important to remember that a lab grade XRF machine is not the same as an XRF gun. While they both operate on the same scientific principles, the lab machine analyzes a homogenous sample and provides results for a load of converters. The XRF gun only gives a reading of the section it’s pointed at.

Inductive Coupled Plasma

While many companies claim they can sample converters, most of them might have an XRF machine at best, or even an XRF gun. The Golden Standard for toll refining companies is the ICP machine, which is much more precise.

The powder sample is converted into a liquid, and the component elements are separated. Plasma flame is then used to make the elements visible. Then the precious metal content is measured against the ceramic substrate by light intensity and the results are indicated as parts per million (PPMs).

Determining the Value of Your Material

With the completion of laboratory analysis, the value of your converters is determined. Processors do this by combining the PPMs of precious metals, net weight of the ceramic, and the market prices for the metals at the time of sale. It’s at this stage that all recyclers are paid, whether the company who assayed the material has a smelter or not.

After the Processor: the Smelter

Your material moves to the furnace once you’ve been paid and the toll-refining process is over. Material is smelted in an arc or plasma.

During this process, the catalyst ceramic floats on top of the furnace and needs to be released in two stages. The first stage of the tap-out is the ceramic. The second stage is to release the metal in the form of slag. It’s important to remember that furnaces need to be fed material constantly in order to work effectively.

Once the initial smelting process is finished, the metals are combined into one mass. Then, the metals are ground down into a fine powder and subjected to chemical leaching. This means that the precious metals are separated from each other into a usable form, or what we call a sponge.

Now they’re ready to be sold on the market.

Metals Are Returned to the Global Economy

When these precious metals are sold on the market, they typically return to the automotive industry. But PGMs are versatile metals and have uses across many industries. Platinum, for example, is used in the production of medical equipment, electronics, and jewelry. Palladium is used in fuel cells, dental fillings/crowns, and jewelry. The majority of rhodium’s use is in catalytic converters but is also used in catalysts for chemical industry, nitric, and acetic acid.

Why Is Recycling Converters Important?

Around 40% of the PGM supply for the automotive industry comes from recycled catalytic converters. That means that a significant proportion of the PGM supply still comes from mining, which damages our environment and depletes our natural resources. There’s also a high cost to mining precious metals, so recycling converters is both beneficial for the environment and a cost-saving measure.

The converter recycling process should now be pretty clear, and with this knowledge, we can confidently say that you should get your material toll-refined and assayed. This is the best way to ensure that you’re getting paid what your material is worth.

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Published: May 11, 2023
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