Shake it up

WHILE the Pilbara may seem worlds away from the tropical downpours of the Amazon rain forest region, its iron ore miners are suffering some of the same problems as their Brazilian counterparts.
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While Metso is still developing its elliptical screen technology, it does hold a lot of promise for screening wet ores.

Metso crushing and screening application specialist Edis Nunes told the AusIMM Iron Ore 2019 conference that screening wet ores was a problem both shared.

One of the problems is the wet ore binds on the screen, greatly reducing throughput.

In Brazil the approach has been to use extra water to help the screening process along when dealing with wet ores.

However, this brings its own issues, not least being the amount of water that gets directed to tailings.

Access to water is also becoming an increasing issue in Brazil. In 2014 the country faced a water crisis after going three months without rain.

In the usually arid Pilbara region wet ores are becoming an increasing issue as miners get below the water table.

They too are facing similar problems to their Brazilian counterparts when it comes to trying to screen the ore.

To get around this, Metso has been working on screening techniques that can work with wet ores.

Nunes said the company was first called in 2007 in Brazil to eliminate wet screening.

Over the years it has tried a number of different screening approaches including an endless circular screen and traditional banana screens, all with varying degrees of success.

However, it was the development of an elliptical screen that started to show promise.

"It gave good performance in both dry and high moisture conditions," Nunes said.

"We had some mechanical issues. The development is still ongoing."

Nevertheless, Nunes said, the elliptical screen showed the most promise when it came to screening wet ores.

"You need to know what acceleration and what the ellipse angle should be," he said.

"Normally flexible rubber is the best screening media."