Umicore Precious Metals Refining is one of the world’s largest precious metals recycling facilities. This plant recycles very diverse waste streams containing precious and other non-ferrous metals. More than 200 different types of raw materials are being processed here, varying from complex mining concentrates and refining residues coming from the mining industry and other smelters up to precious metals containing production scraps and end-of life materials such as electronic scrap and car catalysts. All these materials need to be sampled and analysed, of course, to determine the metal content (and so the value) of each individual lot. It is clear that heterogeneity rules in this process! Next to the obvious heterogeneity of the material itself, there is also a huge variety e.g. in lot size, in packaging, in physical appearance of the different materials, … which is also to be taken into account during the sampling process. To take all these hurdles, the necessary resources are … unfortunately… – not unlimited.

In this article we will gain more insight on how this complex problem is tackled in practice within Umicore, with respect for the Theory of Sampling. A couple of major specific sampling lines have been developed and designed in particular to be able to deal with the variety in physical appearance of the materials itself. Additionally, a large number of sampling procedures are made up in a modular way, to be able to cope with the necessary flexibility demanded for. Some examples will be illustrated and described more in detail, with specific attention to the most important influencing circumstances. Furthermore, the way the overall performance and quality of this whole process is supervised, will be explained. And finally, we’ll discuss some special cases where “nothing seems to be what expected for”…