Metso has launched two new developments in comminution equipment in the form of HRC, a major step in the profitable application of high pressure grinding roll (HPGR) technology; and a new concept in mill liners, the new Megaliner Poly-Met shell liner that maximises mill availability while improving worker safety. For HRC, Metso has made several key innovations in order to increase throughput and decrease total cost of operation. Metso’s patented Arch-frame creates an even gap setting across the width of the tyres, limiting skewing that can result in downtime for mining operations. This anti-skewing Arch-frame also prevents damage to the roller bearings (caused by misalignment) that can occur with the traditional HPGR design.

Used in place of spring-loaded cheek plates, flanges keep the bed of material within the crushing zone and prevent material from bypassing the tyres. This enables greater circuit capacity and increases the overall crushing efficiency. In addition, by preventing material from bypassing the tyres, even pressure across the width of the tyre is better maintained. By distributing the pressure more evenly, the tyre life is maximised by preventing a “bath tub effect,” in which the center of the tyre wears faster than the edges. Victoria Herman, Metso’s Product Manager for the HRC, notes that this breakthrough design is a response to the growing needs in the mining industry. “Energy efficiency has been attracting our customers to HPGR technology for years,” she says. “But our design concept increases capacity and crushing efficiency – and that’s something mining companies are always looking to improve on.” Other notable benefits of the HRC include the hydraulic cylinders, which are positioned to create a compact design while still providing excellent crushing strength; dust enclosure to minimise dust and reduce noise; a transporter facilitating safe and fast tyre replacement; a feed hopper include liners designed for long life; and studded tyres that maximise tyre life by building up an autogenous layer.

Metso has also presented. a new concept in mill liners. The new Metso Megaliner shell liner keeps downtime in large mills to a minimum, utilising an innovative design that offers speedy replacement. It also improves worker safety during maintenance, as the liners are bolted into position from the outside of the mill, so workers do not need to stand in the ‘drop-zone’ of the liners. Mill availability is improved through faster liner replacement. Megaliner uses larger than average liners, yet these can still be placed with the same 6 to 8 axis liner handlers used with many large AG mills. Using larger liners means mills require fewer of them and Megaliner also has fewer attachment points compared with conventional liners, speeding up installation even further. Liners are easily and accurately positioned before bolting with the aid of highly visible, coloured guiding markers.

Megaliner weighs up to 60% less than a metallic liner of similar size. The system makes removal and replacement of liners just as quick, safe and easy as installation. Bolting and unbolting is straightforward as the threaded portion of the standard hex-head liner bolts is protected from dust, corrosion and general mechanical damage. Once loosened, it is often possible to remove the liner bolts simply by hand-turning them. Pneumatic or recoilless hydraulic hammers are not needed to dislodge worn Megaliners, as gravity alone is generally sufficient. The Megaliner is suitable for large AG mills with large trunnions and where modern liner handlers are available. Each Megaliner element integrates multiple lifter and shell plate rows, and covers an area up to 4 m2. The rubber / metal composite liner weighs between 30% and 60% less than metallic liners of a similar size. Overall installing and replacing mill liners with the Megaliner system creates a much safer and less stressful environment for the liner handler operator and the installation team.

Paul Moore is Editor of International Mining magazine – www.im-mining.com