The design and operating principle of Metso Outotec’s HRC high pressure grinding roll has been well proven since going commercial in 2014.

The elimination of the edge effect with a flange design brings with it high throughput, while the anti-skew assembly means customers find faster machine restarts and no downtime from skewing events.

These benefits have been proven at Freeport McMoRan’s Morenci mine, in Arizona, USA, with the company’s largest unit – a HRC 3000 – having now processed more than 120 Mt of ore at that operation. This HRC 3000 is still going strong.

Yet, there was room for improvement, hence the reason Metso Outotec has just released the HRC™e HPGR.

Christoph Hoetzel, Head of Grinding business line at Metso Outotec, explained the rationale for such an update.

“To enable this flange technology, it was very important to have a simple, mechanical solution that works under any circumstances,” he told IM. “Our solution with the HRC was the arch frame, which was a mechanical fix to keep the rolls parallel at all times.

“This, however, came with a compromise. You had to have access to both sides of the machine and, in general, the units were relatively heavy and tall.”

These attributes meant that, if the customer investigated the total installed cost of the HRC – especially if they were weighing the purchase of more than one unit – the cost sometimes outweighed the benefits.

“This was a case of where the economics did not match the sustainability and efficiency of the unit,” Hoetzel said.

Metso Outotec has listened to customer feedback with the HRCe.

“The enabling factor for the flange technology is a mechanical solution for eliminating skewing on the machine,” Hoetzel said. “We have now achieved this with a much simpler, compact design. This is really where the step change has come from.”

Now, when you look at the specifications of the HRCe, which comes with a large feed size acceptance of 60-120 mm and typical capacities of 1,810-6,930 t/h, the footprint is almost the same as other HPGRs on the market, according to Hoetzel.

“Yet, the unit benefits from the proven and reliable flange design of the original HRC,” he said. “You could, potentially, even use a smaller unit for the same application.”

By reducing the size and associated installation cost that comes with the HRC technology, Metso Outotec is suddenly levelling the HPGR playing field. The advantages the company spelt out back in 2014 when the HRC technology was originally publicised now come with no cost drawbacks.

With more miners looking for not only energy-efficient grinding solutions in their flowsheets, but processing options that reduce their water intake, HPGRs are increasingly being used in tertiary or quaternary crush applications, or in lieu of traditional SAG mills.

In this regard, an updated HPGR is coming to the market at just the right time.

Metso Outotec, cognisant of this trend, has also sought to offer the benefits of its HPGR technology to the wider market.

The mechanical skew control HPGR (High Pressure Grinding Roll) retrofit kit takes the key components responsible for minimising skew from the HRC and makes the technology more accessible without the major investment or need to acquire a new machine, according to the company. The technology can also be incorporated into non-Metso Outotec machines.

These latest product updates are in keeping with Metso Outotec’s defined purpose of “enabling sustainable modern life”, fitting the mineral processing reality that miners face today.

Hoetzel reinforced this message: “Customers should not have to choose between sustainability and lowest total cost of ownership with their machines. At Metso Outotec, we truly want to be the partner for positive change, which means we really need to combine both.

“With the HRCe, we think we have achieved that.”