An overview of the role of the pgms in the glass industry

The platinum group metals (pgms) have been used for many years in the glass industry. Due to their high melting points and superior resistance to corrosion, they are invaluable for protecting manufacturing equipment from attack by molten glass and corrosive vapours. Although the initial cost of pgms may be high, they are fully recyclable and, depending on the product, 95% to 98% of the metal can usually be recovered and converted into revenue once the useful life of the component is over.

Established products include platinum-rhodium fabrications, which are self-supporting parts or linings usually made of welded sheets of platinum alloyed with between 5 and 20 wt% rhodium. Platinum-rhodium alloys with dispersed zirconia particles can give fabrications increased mechanical strength and durability.

The deposition of a thin layer of platinum or platinum with 10 wt% rhodium can also be used for ceramic protection in the manufacture of all glass types. Coatings use a lower weight of precious metal than fabrications and are ideal for long runs with limited thermal cycling.

Alloys of platinum with 5 wt% gold are used both in the form of fabrications and as coatings on ceramic substrates, but are generally only suitable for lower-temperature applications.

Recent developments in manufacturing capabilities at Johnson Matthey Noble Metals in Royston, UK, have now made it possible to use iridium in the glass industry. Like platinum and rhodium, iridium is recyclable; but, with a substantially lower metal price, it is more affordable upfront. Iridium has high mechanical strength and excellent creep resistance and can be used under mildly reducing conditions.

A choice of pgm-based technologies is therefore available to the industry and this flexibility ensures that both protection and metal use can be optimised. Every glass plant has its own unique characteristics and trials of various forms of pgm protection can be undertaken to establish which technology is most suitable in each case.

According to Christophe Couderc, Business Development Manager (Glass) at Johnson Matthey Noble Metals, expected benefits of pgm protection include improved glass quality and more sustainable manufacturing. Protection on furnace parts such as the throat will extend the life of a glass furnace, potentially offering considerable return on investment. As the globalisation of the glass industry continues to reduce end-product prices, even while higher technical specifications are demanded of manufacturers, pgm protection of manufacturing parts can offer significant competitive advantages.

Source:

Platinum Group Metals in Glass Making (07/10)

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