The hardmetal particles are very heavy and in order to keep the
particles in suspension, it is necessary to use a feed tank with agitation. The
feed tanks used for the hardmetal
spray drying plants are specially designed to deal with this
issue.
A fluid pressure nozzle is used to atomize the hard metal suspension. The
nozzle is placed pointing upwards in the conical part of the drying chamber.
This allows that the spray can be dried without semi-wet deposits in drying
chambers of limited volume.
A PC/PLC based operator system with recipe color pop-up menus are used to
control and monitor the plant operation, ensuring the constant conditions
necessary to obtain a reproducible free-flowing press body powder of high
uniform quality.
All GEA Niro plants comply with the strictest requirements to health, safety
and environmental compliance. GEA Niro’s expertise in explosion control design
is unequaled and an invaluable aid whether looking at ATEX, other European safety directives or at local
regulations.
An advantage of operating with an inert atmosphere is the reduced risk of
oxidation degradation of the hard metal powder and the reduced emission of
solvents and solids. The closed cycle drying plants for hardmetals supplied by
GEA Niro also include automatic CIP
(Cleaning-In-Place) of the essential parts.
Hardmetals
Hardmetals are most often carbides primarily
of tungsten. Hardmetals are typically used for manufacturing of cutting or
mining tools, but hardmetal powder can also be used to spray coat other
materials. Hardmetal powders for cutting and mining tools are mainly produced
as ready-to-press powder in one single drying operation from a formulated
suspension of hardmetals.