Articles

Material Losses in Processing

Posted by  Alice
21 Aug 2019 0 comments

 

 

There will always be a discrepancy between the specified content of PGMs (Platinum Group Metals - Platinum, Palladium, and Rhodium) at the time of manufacture and the actual amount recovered after processing. It is estimated that this discrepancy is a loss of around 15% in volume and 20% in value. The higher loss in value terms is due to the costs associated with the smelting and refining processes involved in PGM recovery. These losses can be quantified in two areas:

 

Pre-processing losses

As the scrap catalytic market grows and becomes more professionally managed, the players in the industry have more information available to them in terms of the quantity of PGMs in each of the many thousands of catalysts that now exist. Reliable, comprehensive catalogs now provide up-to-date information on both content and prices, based on the latest market information. Most of these rely totally on the catalytic converter manufacturer's specifications. However, variations from these “as new” specifications can occur for several reasons:

 - depending on the age of the catalyst and vehicle usage, physical disintegration can occur during the life of the catalytic converter

 - during dismantling, storage & transportation stages prior to processing, sometimes the monolith (“honeycomb”) may become damaged or broken which can result in some losses

 - the crushing and sampling stage, if not carried out properly, can also result in losses

Almost by definition, these losses are hard to estimate and the only way to accurately determine the exact PGM content is by a full analysis of the crushed monolith material prior to processing. The better-equipped processing operations can provide in-house or external laboratory analysis. Alternatively, handheld X-ray Fluorescence (XRF) spectrometers provide accurate and precise measurements, almost to laboratory standards.

Processing Losses

Losses during physical processing can be split into two categories:

 - those that result from the metal recovery techniques

 - those financial losses as a result of the processing fees of the smelters and refineries

A number of different processes are used to recover PGMs from scrap catalytic converters. These include hydro-metallurgical and pyrometallurgical techniques as well as other more innovative means like deep eutectic solvents or ionic liquids. Typically though, the process for the economical processing of large quantities of PGM-bearing material is in two stages:

 

Smelting: the most common smelting method of the crushed monolith is pyrometallurgical treatment, using a high-temperature furnace such as a plasma arc process, which deposits a PGM-enriched alloy. A small proportion of the PGM’s is lost to the slag during this process, with final recovery usually around  97% for Platinum and Palladium, but as low as 85% for Rhodium.

As well, depending on what method of charging has been agreed with the smelter, smelting costs will be up to $3.50 / kg of a monolith or up to 5% of the value of the PGMs extracted.

Refining: recovery and separation of PGMs to the point that they reach a purity of 99.95% (the standard required by LBMA - The Global Authority for Precious Metals) requires highly technical and expensive refining techniques. Typically refiners will hold back a negotiable percentage of the recovered PGMs to cover their fees which results in a financial loss for the scrap dealer.

As stated previously, these mount up and can result in metal losses of around 15% and cash value losses of around 20% when compared with the volume and value of PGMs in an “as new” catalytic converter.

One final thought when considering the potential profit from any batch of scrap catalysts, it is also important to bear in mind currency fluctuations. These can move up and down surprisingly quickly and keeping up-to-date with market trends is well worthwhile, in terms of deciding when to sell.

Thus, in summary, when financially planning for the future business, these variables need to be borne in mind - they can have a marked impact on profitability if not taken into account.