Research Study Leads Kwatani to Better Banana Screen Design
Posted by Paul Moore on June 8, 2021
Numerical simulation research that modeled the behavior of particles on a conventional banana sieve was leveraged by local vibrating sieve specialist Kwatani to make fundamental improvements to the design. Kwatani’s adaptations were so extensive that they were able to double the throughput of a competitor’s problematic dewatering screen at a customer’s mine, where excessive water entrainment limited production potential.
According to Kwatani COO Kenny Mayhew-Ridgers, the depth of the company’s mechanical and metallurgical expertise underpins its ability to apply what it learns from research and field testing. “This specific research, which was carried out by the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) and the University of Queensland, found that the traditional feeding slopes of banana screens were generally too steep. “says Mayhew-Ridgers. “At around 34 °, these slopes create a material velocity of more than 3 m / s – too high for effective screening. “
He considers that a more suitable slope at the feed end is 25 °, leading to five or six bridge slopes in the screen and ending with a discharge slope of only 5 ° or even 0 °. This would ensure that the material speed was less than 0.5m / s at the discharge end. The drive angle, operating speed and stroke are also important factors, he says.
“Our analysis allowed us to address a challenge that a customer was having with their degreasing screens,” he says. “Transferring water from the screen to the conveyor belt limited the throughput to just 250 t / h, and the mine needed more than that.
Kwatani changed the feed slopes of the screen and incorporated a 3 ° long discharge end decline slope. The drive angle has also been increased to 50 ° to improve the sieve dewatering performance. These adaptations were possible within the framework of the constraints of the existing chute works, the position of the engine base and the support structure. The size of the screen – measuring 3.66m wide – meant that a considerable load had to be supported on the screen deck, so the circular hollow sections offered improved strength in place of the H-profile bridge beams. usually used.
“The changes have been successful,” he says. “The mine plant manager was able to confirm that the feed rate had been increased to 500 t / h with very little water entrainment, and this performance was consistently maintained.
The application of the new design was described in a peer-reviewed article by Mayhew-Ridgers and Kwatani director Derrick Alston, which was presented at an international conference on mineral processing.