FMG aims for a cut above the rest

Emerging iron ore producer Fortescue Metals is preparing for a field trial of the CSIRO-developed SMART*CUT rock-cutting tool. Sarah Belfield writes for Australian Mining

Perth-based iron ore outfit Fortescue Metals is exploring the avenues for cost savings with the surface mining technique and part of this campaign will involve scrutinising the CSIRO-developed SMART*CUT rock-cutting tool. Fortescue is now gearing up for a pending preliminary field trial of this technology.

When applied to rock-cutting in mining, the SMART*CUT technology involves thermally stable diamond composite cutting tips that have been mounted onto the rock-cutting picks traditionally used in the industry.

The diamond composite particles are held together by a silicon carbide binder.

The composite has been a winner in the laboratory, with the new tips showing a very low rate of wear-flat development, even after large cutting distances were racked up.

To date, the mainstay of rock cutting in the mining industry has been the tip composed of tungsten carbide particles in a cobalt binder.

But the SMART*CUT configuration has begun to capture imaginations in industry, with Fortescue being one company prepared to step up to the plate and see if the technology will work at a commercial scale in the real world.

Fortescue’s involvement was prompted by its decision, following trial mining in late 2005, to go with surfacing mining at its tenements rather than take the conventional iron-ore mining route of rock blasting and shovelling. And while one could argue that equipment manufacturers might be hesitant to embrace any change away from tungsten carbide pick tips, Fortescue convinced German-based manufacturer Wirtgen to join in on SMART*CUT trials.

At the time of writing, Fortescue had 10 of Wirtgen’s 2500 SM surface miner machines on order and was expecting to begin taking delivery of this initial fleet mid-year.

Each machine features a 2.5-metre wide cylindrical rotating cutting drum concealed beneath the middle of the chassis.

In a process resembling a paddle steamer, the picks mounted on the drum claw upward into ore as the machine slowly wheels forward.

The broken ore picked up then swings around and over the drum and onto an internal conveyor belt.

Finally, the ore moves out onto a rear boom, which can direct the ore into a haul truck. Fortescue is aiming to assess the merit of using SMART*CUT pick tips on its surface miner machines.

The company will be doing this as part of wider trials involving other surface miner components such as the cutting drum and pick holders.

One of the roles Fortescue’s David Mendelawitz plays within the company is managing these sorts of special projects.

“For us there are lots of benefits in having a pick that doesn’t wear out,” Mendelawitz told Australian Mining. Mendelawitz said the main benefit of longer-life picks would be the end of unscheduled surface machine down-time.

It would remove the opportunity cost of powering down a machine for say 20 minutes just to change to fresh picks – a machine that could have been producing ore.

By ruling out unscheduled down-time, the economics of pick changing would therefore merely involve the cost of the picks and labour used.

And so Fortescue was prepared to pay a higher price for picks that removed the much larger opportunity cost of production stoppages.

In its bid to commercialise the SMART*CUT technology, Fortescue intends to first put the new pick materials through its paces in a quarry featuring some of the hardest rock that can be found.

In this preliminary field trial, Mendelawitz wants to push the technology to its current limits to see what it’s capable of.

He will be looking at what break-out forces and abrasivities the pick tips can handle.

“It might be in the first minute, it might two months later, but what we’ll be after is mechanisms of [tip] failure,” he said. He will also be assessing the best angle at which the picks hit the ground, known as the attack angle.

“Diamond composites, being very hard materials, work very well in compression. But when you put a component of shear onto them they don’t work as well as traditional tungsten carbide.

“So we need to optimise those angles so we can have [the tips] in compression as much as possible without affecting the actual cut rate, particle sizing and the impact of vibrations on the machine.”

SMART*CUT will then go back into the lab in the hope the performance bar can be raised. Later, all of the preceding work would be reviewed to judge whether extensive field trials were warranted, Mendelawitz said.

“There are a lot of sceptics about this technology – it might stay on the drawing board for a while. We believe it’s worth taking through to the end to see where we can optimise it,” Mendelawitz said.

“We’re pretty close to getting all this technology right. If we get it right, it’s a huge amount of money [saved]. We believe that the work we’ve done has gotten over the major barriers.”

As a technology, work on aspects of SMART*CUT goes back at least a decade.

According to CSIRO Exploration and Mining research leader Hua Guo, a consultant for an Australian manufacturer had first brought thermally stable diamond composite to researchers’ attention and suggested the material should be able to cope with cutting hard rock. It was then in 1996 that initial rock cutting trials took place using the diamond composite.

“The very first cutting trial on a granite was an outstanding success, much to the delight of the research team,” Guo told Australian Mining.

He said while hurdles would arise for the researchers in later years, they realised early on that the diamond composite had great potential in mining industry applications.

What enabled the creation of SMART*CUT as we recognise it today was the watershed development of a process to bond the composite to the steel body of the rock-cutting pick.

Guo said while the feasibility of commercialisation was still being gauged at this stage, the materials scientists, engineers and technicians involved in SMART*CUT were excited at the prospect of having their technology tested in Fortescue’s field trials.

“There is a giant step in migrating this laboratory-based technology to field trials,” he said.

“In many respects, it will be a relief to have the picks demonstrated to the mining industry [and there is also] the hope that they perform to the level repeatedly demonstrated in the laboratory cutting trials.”

Guo said the steel bodies of picks may now be the limiting factor in rock-cutting wear processes, so the upcoming field trial would also involve test runs of several picks featuring not only SMART*CUT tips but also steel bodies with a wear-resistant coating.

David Mendelawitz

Fortescue Metals Group

08 6218 8888

Dr Hua Guo

CSIRO Exploration & Mining

07 3327 4608

Dr Xing Li

CSIRO Exploration & Mining

07 3327 4634

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