The process for making metal granules and powders is an established technology that involves melting metals in 500 kg induction furnaces. The liquid metal alloy is then poured from its crucible into a water-cooled chamber to produce the required size of liquid droplets. Inside the chamber the metal droplets are quenched to solid granules by water and air, or they fall onto a water-cooled metal plate and by controlling the process parameters the shape of the granules can be varied from needle, irregular to spherical. The constant availability of water, at predetermined pressures to the spray nozzles which quench the molten metal, is essential to the whole process. The higher the water pressure used in the atomisation process, the finer the granules or powders. This places a high level of importance on the water supply system and the pumps involved. It is also a hostile, unforgiving working environment.
ECKA uses a closed loop recycling system in order to optimise the use of water, which contains biocides and inhibitors. The water is pumped into the atomisation process at temperatures between 10°C and 16°C. However, when it returns into the closed loop the temperature has risen considerably so is has to be chilled before it can be re-used.
In order to achieve higher levels of product throughput, it was decided to introduce Cat Pumps triplex plunger pumps as these would give the pressure and flowrates required. The smooth performance of the Cat Pumps’ model 3545 pumps ensures that the pressure through the spray nozzles in the atomising chamber is constant, as any variation would impact on the size of the granules.
The three pumps provide a combined flow rate of 405 L/m at pressures up to 70 bar. A forged brass model, the model 3545, includes secondary low pressure seals with internal fluid recirculation, which provide double protection against external leakage. Whilst the triplex plunger design does give a smooth product flow, Cat Pumps fitted all three pumps with pulsation dampeners to ensure the exact flow required for the granule size would be provided constantly.
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