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‘Spiroflow’ Aero-Mechanical Conveyors – a moving story!

Keeling & Walker Ltd of Stoke-on-Trent, UK is the world’s largest producer of Tin Oxide. Not only is Tin Oxide a very abrasive material, it is very difficult to handle: it smears, doesn’t flow well and readily bridges. So, back in early 2007, when Operations Manager, Martyn Pedley, came to choose a replacement for a troublesome bucket elevator, he was concerned to find a conveyor that would be man enough for the job and, in addition, which would eliminate the fugitive emissions to improve the working environment too. The problems with the bucket elevator were caused by the abrasive product getting into the chains and other mechanical parts. As a result, it had become too costly to maintain.

After trawling the pages of the technical magazines, that Martyn Pedley keeps on his office shelves for reference, he concluded that either a Flexible Screw Conveyor or an Aero-Mechanical Conveyor would be possible solutions. Accordingly, he contacted 3 companies and made arrangements to conduct trails at their respective Test Centres. He included Spiroflow among the 3 because of their technical article comparing the merits of various conveyor types published by one of the titles.

However, continuous trials here at Spiroflow soon indicated that, over time, tin oxide would smear onto the inside wall of a Flexible Screw Conveyor conveying tube; building up to the point where it would likely bind and cause premature failure. As a result, the trials were re-run in an Aero-Mechanical Conveyor and all the indications were that this was the ideal solution. This has been verified by the ‘Spiroflow’ Aero-Mechanical Conveyor installed in March 2007 which has performed to Keeling & Walker’s satisfaction since.

Keeling & Walker Ltd, and sister company Thermox Performance Materials Ltd, operate from the same site in Stoke-on-Trent, UK. Between them they offer more than 50 Tin Oxide based materials for use in ceramics, electrical, electronics and advanced technology applications. They are based in Stoke as their origins were in the supply of materials for the local ceramics industry. Although that industry has declined, the company has successfully developed Tin Oxide products for new applications as well as expanding to service the ceramics industry globally. Today, a staggering 95% of their production is exported – which is great news for the British economy! High purity tin is sourced on the commodity markets around the world and transformed into oxides of many varieties and grades by both thermal and chemical processes.

Over the last 2 years, Keeling & Walker have invested heavily in improving the efficiency of their production processes to remain competitive in their global market. Martyn Pedley set about upgrading the packaging lines to reduce its labour intensive nature and to eliminate dust in the atmosphere. To do this, additional conveyors were required to transfer Tin Oxide from the reverse-jet filter hoppers, where it is collected after undergoing the thermal process, to the storage hoppers above the packing machines.

According to Martyn Pedley, “Spiroflow Aero-Mechanical Conveyors were my automatic choice, I didn’t look elsewhere based on the performance of the unit installed in March 2007, the service that I received at that time and the after sales service I have enjoyed since. There was a minor teething problem with the first conveyor. A Spiroflow Service Engineer not only remedied that very quickly, he even took the trouble to stop by a few days later to check that all was still well”. Mr Pedley continues, “The fact that the conveyors are totally enclosed has made a massive difference to the cleanliness of our factory”.

Keeling & Walker bought a further ‘Spiroflow’ Aero-Mechanical Conveyor in February 2008 and then 2 more in September 2008. The original conveyor is 3m long and operates vertically; the other 3 are 5 meters long and operate at around 50 degrees to the horizontal. Aero-Mechanical Conveyors can operate at any angle from horizontal to vertical without any change in performance. The ‘Spiroflow’ Aero-Mechanical Conveyors at Keeling & Walker operate continuously 24/7.

Keeling & Walker’s Tin Oxides find applications in ceramic colours and glazes, electrodes for glass melting, electrical contact materials, electrical and electronic components, brake pads, polishing materials, sputtering targets, antistatic coatings and fillers for plastics, transparent electrically conductive materials for flat panel and CRT displays, transparent infrared-reflective coatings for energy-efficient glass, as well as for catalysis, gas detection, medical and many other applications. To learn more about Keeling & Walker, their products and their applications, visit their website at

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