Precious metals in pharmaceutical processing
Precious-metal catalysts are typically supported on carriers. Carbon supports are the most common carrier media for precious metal-bearing catalysts in the pharmaceutical processing industry. Heterogeneous palladium on carbon, platinum on carbon, palladium on alumina, and palladium on calcium carbonate are examples of catalysts and their supports that facilitate hydrogenation of intermediates. These catalysts do not last forever and, when spent, the PGMs from the catalysts need to be recovered. A precious-metal refiner can be used for this function.Precious-metal recovery and refining
Equipment. Most refiners use a wide variety of equipment to process spent catalysts. This equipment includes rotary and crucible furnaces, kilns, roasters, thermal processors, pulverizers, granulators, screens, blenders, auto samplers, reactors, dissolvers, precipitators, electrolytic cells, and filter presses. In selecting a precious-metals refiner for a partner relationship, a pharmaceutical manufacturer should be aware of some of the key steps within the refiner's process and how the various equipment and tools are applied to spent catalyst lots. Sampling and assaying are two of the more important procedures that help to ensure optimum return of PGMs from spent catalysts.
Sampling techniques. Precious-metal refiners generally use three different sampling techniques: dry sampling, melt sampling, and solution sampling. The choice of method depends on the type of material to be processed and its precious-metal content. Because most catalysts for pharmaceutical processing are based on carbon, dry sampling is often applied to these materials. Dry sampling is the most complex of the three sampling approaches and is used when materials cannot be dissolved in a solution or are not suitable for melt sampling because of their structure. Because it is difficult to achieve true homogeneity by means of dry sampling, refiners using this technique should have expertise and sound judgmental skills. And for maximum sampling accuracy, spent catalysts must be properly prepared prior to dry sampling.