Pumps switch at metal atomisation plant

Wednesbury, UK – UK metal powders producer ECKA Granules has recently installed new pumps technology to improve the performance of the atomisation lines at its Wednesbury plan in the West Midlands.

The facility has a capacity to produce over 3,000 tonnes per annum of nickel, cobalt and stainless steel powders for the thermal spray, surface coating and welding industries. The plant operates 24/7, employing a batch production process that takes over three hours to complete.

The company’s 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 10ºC and 16ºC. 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.

To improve productivity, at the end of 2011 the company invested in a new pumping system in order to achieve greater flexibility in its water atomisation line.

This included the introduction of three triplex pumps, from Cat Pumps, to augment the existing high pressure pumping system, which relied upon two pumps operating in tandem to generate the required water volume and pressures up to 190 bar.

Whereas these pumps were effective in generating the high pressures required for producing fine powders, when it came to the lower pressures required for larger granules, typically around 70 bar, the pumps were inefficient.

The new triplex plunger pumps were chosen as these would give the pressure and flowrates required to raise product throughput – any variation in these parameters could impact on the size of the granules

The pulse-free performance of the Cat Pumps’ model 3545 pumps is said to ensure that the pressure through the spray nozzles in the atomising chamber is constant. The pumps were also fitted with pulsation dampeners to ensure the exact flow required for the granule size would be provided constantly.

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.

This was the first time that ECKA have used triplex pumps noted Andrew Baker of ECKA Granules, who reported: “After more than six months of operation, we have seen the improvement in productivity that we wanted to achieve, and the pumps have provided the service and reliability that we required.”