Advances With Large Rotary Blasthole Drills

BHP Billiton recently purchased 18 autonomous upgrade packages for its fleet of Atlas Copco Pit Vipers. (Photo: Atlas Copco)

 

Blasthole drilling is one aspect of open-pit mining that engineers identified long ago as a promising area for autonomous operations. Unlike haulage and loading operations, which are much more dynamic and complex with several pieces of equipment interacting in a 3-D environment, drilling a blasthole pattern on a bench is a very repetitive process. Over time, the task has evolved from automated drilling operations to hole location via GPS to teleremote operations to today’s autonomous operations.

Much of the advances in autonomous mining operations are taking place among iron operations in the Pilbara in Western Australia. Rio Tinto and BHP Billiton have been investing a significant amount of money in automating operations in an effort to improve safety, reduce costs and improve the quality of life for their miners. During June, Atlas Copco announced that BHP had purchased 18 autonomous upgrade packages for their large rotary blasthole drills operating in the Pilbara.

Ultimately, the goal with automation in this area is to drill a fairly accurate pattern consistently. Three key considerations for drill automation should be: safety, repeatable operations (consistency) and utilization.

Not every open-pit mine is as easy to operate as the relatively flat iron ore operations of Western Australia. Similarly, not every mine operator is interested in fully autonomous operations. But, it’s safe to say that these days every mine operator is looking at ways to blast as much rock as they can with a consistent level of fragmentation at the lowest cost. Today, they can capitalize on some of the steps developed along the way toward full autonomy by tailoring a drilling program to meet site-specific needs. Manufacturers such as Joy Global confirmed that in the not-so-distant future, miners should expect to see more in this area of modularization.

BHP Takes the Lead With Autonomous Drills

For the past two years, BHP Billiton has been running a trial of Atlas Copco’s autonomous technology on Pit Viper 271 rigs at the Yandi mine. The machines have operated autonomously for more than 15,000 hours and drilled more than 1 million m.

As a result of the successful trial, BHP Billiton has ordered autonomous upgrade packages for 18 drill rigs, in addition to a couple of machines already operating autonomously. The autonomous rigs will initially be controlled at BHP Billiton’s five iron ore mines in Pilbara, with the longer-term aim of remote operation from Perth, more than 1,000 km away.

“We are committed to delivering the most innovative solutions that enhance customers’ productivity, and our autonomous drill rigs are a fine example of that,” said Johan Halling, president of Atlas Copco’s Mining and Rock Excavation Technique business area.

Altogether there will now be 20 PV-271 autonomous drills deployed across BHP’s five Pilbara iron ore sites: Yandi, Mining Area C, Jimblebar, Mount Whaleback and Eastern Ridge. The rollout will occur in a staged process between now and July 2017.

All blasthole drilling at those sites will become autonomous, according to Luke Purvis, key customer manager for Atlas Copco. “The drills will initially be operated from site but will become remotely operated from BHP’s Integrated Remote Operations Centre (IROC) in Perth from December,” Purvis said. “Atlas Copco will also base staff in the IROC to help monitor the drills.”

Atlas Copco has also been working with Rio Tinto on various drilling automation projects, Purvis explained. “It is understood BHP Billiton, while not as far down the autonomous haulage and data analytics paths than its Pilbara rival, is much further ahead on the autonomous drill front,” he said.

According to Purvis, BHP’s autonomous PV-271s can tram themselves out to where they need to drill, locate where they have to drill much more accurately than a human operator could, drill the hole, and move to the next. “They can drill an entire pattern autonomously, even managing jamming issues within the hole,” Purvis said. “The rigs can also call for water and fuel as they need it. Should the rig get into problems, an operator can take control of it remotely and help it out.”

At the Drill and Blast Summit in Brisbane in April, BHP’s mine automation readiness engineer, Jack Chaston, said autonomous drilling led to increased machine utilization and consumable life. He said the autonomous PV271s were 16% faster per hole, had 20% additional utilization and one-third extra drill capacity.

BHP Billiton WAIO Asset President Edgar Basto said technology was having a significant impact on productivity across the industry. “Through our trial at Yandi, we were testing how this was going to work in our operations and making sure there was a business case, and then we started to see the benefits,” he said. “We were able to do this relatively quickly because they [Atlas Copco] had already done the work.

“We are creating a safer working environment for our people…they will now be operating in our control room so we are driving collaboration with this.

“The predictability of the drilling operations is going to be a lot better—we have seen that already. There is consistency in the way that autonomous drills are performing.”

The Atlas Copco system is a modulated automation system that can be adapted from semiautonomous teleremote to fully autonomous operation depending on the mining operational requirement.

 

New Drills, New Technology on the Way

Looking at the markets segments, Matt Collins, product manager for drills at Joy Global, readily admitted there are some gaps in the line of P&H rotary blasthole drills. “We currently operate at the large end of the spectrum—hole diameters up to 17 inches, dropping down to 7 7/8 inches,” Collins said. “During a review of our existing product line, we also began to look at possible incremental improvements to the product line.”

All of the current Joy Global blasthole rigs use rotary tricone bits. With the recent MTI acquisition, however, the company gained access to most of the drill string components, including some down-the-hole hammer technology. “This is a new area for us and we’re exploring our options as far as hole diameters less than 8 in.,” Collins said.

One of the areas missing from the Joy Global product line was automation for surface drilling. Obviously, this is a hot topic among the miners and a few years ago, Joy Global began to work on an automated system for bench drilling applications. “Right now, we have an existing effort on drill automation that we’re testing in the field, and we have an additional initiative to develop new machines to round out the company’s offering,” Collins said. “With the MTI acquisition, we acquired most of the drill string—everything but the bits. We are strengthening our product line. We have added a number of engineers and key people. We have an excellent existing service network and a really good footprint to introduce some new products.”

Joy Global has developed a new automated control system, which can be operated by line of sight up to a mile away. The system offers high precision GPS and the company routinely sees accuracy with as little as 10 cm deviation on drill hole location. “The system is a traveling kit that can be placed in a pickup truck,” Collins said. “We have also added a GPS depth aspect, so the controls take the x, y and z axis into consideration during drilling. Sometimes the operators level the jacks and the machine is positioned higher than it should be. By using the rated depth feature, they can be sure they will remove that hard toe.”

The off-machine console is a little smaller than a suitcase. It folds open to a monitor and a set of joysticks pop up out of a well. The screen replicates what would be seen onboard. The joysticks are the same. With Autodrill, the screen is split. “Operators can page through and find the view they prefer,” Collins said. “On the right hand side, a series of cameras offers 360° views around the machine. There is another camera trained on the deck and the drill bit.”

These control systems can be retrofitted to existing drills. “The scope of the project was to improve the electrically powered 320XPCs with a control platform similar to the Centurion system that was launched for electric shovels,” Collins said. “The second part of the project is to fit it into our future product line, which we are in the process of developing right now.”

Joy Global plans to debut this new drilling system in a few months at MINExpo 2016. He said the idea for the backbone architecture was related to the innovative design that drives the patented Switched Reluctance Hybrid loader technology, which was discovered when the company acquired the Le Tourneau line of large front-end loaders. “Le Tourneau had some advanced technologies that we can use to help achieve a common control platform across all of the equipment,” Collins said. “If we have a service tech tracing faults and failures and each week the tech is moving between a drill, a hybrid shovel or an LHD underground loader, ideally the technician would be working with the same control platform. That would mean a huge improvement in efficiency. Plus, with a standardized offering, the technicians are using the same components and there is less inventory on the shelf, such as digital and CAN-analog cards that are common from one to the next. They can replace the existing system and the software file will make the modifications.

“The backbone architecture is common against what we are doing right now and it has high computational ability for supporting teleremote and ultimately full-autonomous machine functionality,” Collins said.

Joy Global has been testing units in the field. “We have trialed a unit in western U.S. copper and another in North American iron ore operations,” Collins said. “Our field trials have given us some awesome feedback. We have modified a few items on the product as result of safety and performance related input. We are about to release this product commercially. We will do a few more tests and then we will have something superior for the rest of the existing drill fleet.”

The most obvious productivity improvement is the Autodrill function in the hole. P&H has had it for a number of years. “Ultimately, what we did this time was we looked at the period when the drill string backs off and re-engages due to excessive bit air pressure, vibration in the mast or tower, or rotary torque. There is a fraction of second for the system to re-engage the rock,” Collins said. “We have been able to change the sensors and logic to keep the bit engaged for better cycle times.”

When the operators are not on the machine, they have to rely on horizontal and vertical vibration indicators. “We have been looking at rotary RPMs, pull down force, feed rate, bit air, rotary torque, and resultant vibration signatures to establish baseline settings for different geologic formations, essentially an Autodrill cheat sheet,” Collins said.

Part of the plan for Joy Global’s drill automation and baseline architecture program is to systematically grow the product. “So first we establish high-precision GPS, teleremote operation with line-of-sight control for one rig. Then the next step would include obstacle detection mitigation and auto-navigational control with multiple machines,” Collins said. “An operator could be auto-tramming one rig to the next hole location while the other rig is auto-drilling a hole. Synchronized movement.”

When introducing these new systems, Collins cautions people to have patience, especially with machine malfunctions, and the mine’s network, which is usually stretched thin. “Live video feeds chew up a lot of bandwidth for the mine site’s command center,” Collins said. “If they want to capture the feed they have to either push it through the existing Wi-Fi network, and currently there’s nothing robust enough or cost-effective for it, or use two different networks, where one transmits dispatch information and other operational information. Or they can use a stand-alone system for video feeds from remote operations. Understanding a mine’s network is key.”

The first machine in the company’s new product line, the 77XD blasthole drill, will debut at MINExpo as well. The numerical indicator “77” represents the bit load of 77,000 lb of force maximizing at 10 ft-5/8 in. (270 mm) diameter holes. According to Collins, this versatile drill will have a variety of configurations to meet a variety of mining duty applications. The “D” included in the name represents diesel power, whereas the “E” in 77XE would represent an electric trail cable machine. Other options include rotary tricone or DTH hammer drilling, as well as single pass or multipass configurations.

“We have whole bunch of new designs. We know where we fall short compared to the competition as far as cycle times, performance characteristics, etc.,” Collins said.

“We have been looking at a new platform similar to the Centurion control platform,” he added. “We would call this a LINCS-controlled platform or maybe it would be better explained as the next generation of drills. The best way to think of the new machine, the first of which will be on the show floor at MINExpo, is as a base with buildup options thereafter,” Collins explained. “Whereas historically when we would bring a new drill to the market, we would have it armed to the teeth with every possible function, and then as a result the price is substantially higher. If a mine operator simply wants to drill a hole and doesn’t need all of the additional functionality, we can deliver a more cost effective unit. So we are building a customized machine upward as needed to with request that meet certain applications and needs.”