Responding to the needs of the mineral sands sector, process equipment specialist Multotec has developed its first 12-turn spiral concentrator.

Multotec Process Engineering GM Christina Ramotsabi says the HM12 spiral was designed and tested in-house, evolving from the company’s popular NHM heavy minerals spiral.

The first order has been manufactured and shipped to an international customer.

“The customer required higher recoveries from its mineral sands plant, while also achieving optimal grades.

“Our HM12 spiral concentrator will deliver these increased recoveries while still maintaining a limited footprint in the plant,” says Ramotsabi.

Conventional spirals generally feature seven or eight turns, she points out, adding that two stages of these spirals would be required to achieve similar recoveries with one 12-turn spiral.

The use of the 12-turn setup reduces footprint requirements, as well as the use of additional equipment such as pumps, distributors and piping.

The new model was developed through a lengthy collaboration between Multotec’s research and development department, its process team and its engineering team.

Multotec applications engineer Kgabo Mashita says the initial phase of testing used a conventional spiral to generate benchmark results. In the next phases, the feed box was redesigned and evaluated, and re-pulpers were introduced.

“The length of the spiral made it necessary for us to introduce more energy to the slurry mix at certain stages, to renew the separation process.

“We placed re-pulpers strategically on each spiral, to receive and re-energise the slurry, essentially creating a multi-stage separation process,” says Mashita.

He emphasises the critical role of the feed box in optimising the functioning of the spiral. The improved presentation of the slurry feed allows even and consistent distribution as it enters the spiral.

This ensures that more residence time is spent on separation.

The first units were ordered through Multotec International’s Eurasian division and have been shipped to the customer.

A technical team from South Africa will assist in the commissioning and optimisation of the equipment. It will be serviced by Multotec’s agents and supported by the company’s representatives in the region.