Abstract SYMPHOS 2011

HOW IS BINDING ACHIEVED?
Trace Element Attachment is achieved by first adding the coating to wet the granules then adding the required
powder via a powder feeder. The coating will dry on the surface trapping the powder, which due to its small size, is
readily oxidised. Efficiency of the coating process can be enhanced by the following
a) Product temperature – either via heating the coating or monitoring the granule temperature if
adding post production. A gently heated coating (35 – 40 degrees C) spreads further and is more
easily applied with less potential for blockages.
b) Coating in a drum/belt. A drum undoubtedly gives better results but speed and internal contours
should be checked to avoid violent throwing of granules and instead an even tumbling action is
desired. This may require some drum adaptation.
c) Use of a nozzle. Type, aperture, air atomising, flow jet etc.
d) Number of nozzle outlets. A high dosage of coating can be spread over several nozzle outlets
maximising coverage and so minimising product requirement.
SELECTING YOUR POLYMERISING COATING
When selecting a coating the following points should be considered
• The effectiveness of the coating on attaching and retaining the required volume of powder
• Cost effectiveness in terms of yield and result
• Whether you require oil based or water soluble coatings
• The method and equipment for application
• Environmental aspects of the coating – is it soil beneficial and will it comply with European
legislation?
• Health and Safety considerations for the workforce including smell, toxicity and operating
temperature. Whether the coating needs to be applied at 80 degree C - or is classified as a fire hazard
for storage purposes.
• Availability, stability and reputation of supplier
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