MechChem Africa November-December 2020

The thyssenkrupp HPGR Pro: fit for the future With the release of the HPGR Pro, thyssenkrupp is taking crushing and grinding circuits to new levels of operational efficiency: higher throughput, improved product quality, and reliability with much lower production costs. MechChemAfrica talks to Gerhard VanWyk, the process manager for thyssenkrupp Industrial Solutions in South Africa.

“F or decades, our high-pressure grinding roll (HPGR) has been the machine of choice for ef- ficient, high-pressure grind- ing and processing of ores. But our new thyssenkrupp HPGR Pro takes grinding to the next level,” begins Van Wyk. “Through a multitude of innovations and features, min- erals processing plants now have access to better-than-ever throughput, product quality andmachinereliability,whichcansignificantly improve production efficiencies and reduce operating costs – and all of these things are as necessary now as they have ever been,” he tells MechChem Africa . Glbally, vanWyk says that HPGRs started to be introduced in the cement and diamond industries in the mid to late 1980s. In hard rock applications, their use has steadily grown, especially since 2006 with the com- missioning of the first thyssenkrupp HPGR at a large copper mine in Peru, which was soon followed in 2007 when a leading South African platinum producer began to investi- gate replacing problematic SAG mills at its Limpopo mine in South Africa. This mine was struggling to get its semi- autogenous grinding (SAG) mill to do con-

ventional fine crushing of the very competent Platreef ore. The lowefficiencyof this tertiary crushing stagewas causingbottleneckson the feed line into the ball-mill. This drove the mine to investigate a more efficient comminution technology for its new North concentrator plant. After extensive work, an HPGR-based circuit was selected and commissioned in 2007. Originally de- signed for 20 000 t/day, the later addition of variable speed drives enabled a produc- tion increase of 20 to 33% above nameplate capacity. “We have been installing solutions such as these for over 40 years and, worldwide, we now have over 150 HPGR installations for hard rock applications and more than 300 in the cement industry. Over the years, we have made steady improvements, but the new HPGRPro combines the bestmodern innova- tions to create a more efficient and economi - cal solution than ever,” he explains, adding the complete HPGR Pro package typically offers 20% more throughput, 15% energy savings, and rolls that last up to 30% longer. Turning attention to the specific innova - tions included in thenewthyssenkruppHPGR Pro, VanWyk says that several individual de-

sign improvements have been incorporated, which all deliver operational performance enhancements. Rotating side plates The throughput improvement is largely as a result of the shift from using conventional static cheek plates to rotating side plates to keep the feed material running in a uniform line in the gap between the rolls. “Rotating side-plates on fixed grinding rolls improve material feed by up to 20% in terms of throughput. What’s more, the machine’s specific energy consumption is reduced by around15%,” VanWyk tells MechChemAfrica . Explaining why, he says themore dynamic and sealed rotating side plates enable better grinding at the roll edges. “They enable crush- ing across the full length of the roll, which not only crushes more material, but the pressure is better distributed across the grinding rolls. The side plates rotatewith the roll, unlike the static cheek plates that reduce the speed of thematerial close to the edge, which reduces the pressure and increases wear. “Traditional HPGRs produce higher pres- sures in the centre, tapering off towards the rolledges.Rotatingplatesreducepeakcentral

Oil lubrication enables better control of bearing temperatures, since the oil can be circulated through the bearings and back through an oil cooling and filtration system.

6 ¦ MechChem Africa • November-December 2020