Mining projects can be dangerous jobs that are difficult to manage, and when things go wrong, the consequences can cost millions.

But a new system is tackling both safety and productivity, which could have gains both in Australia and overseas.

The Cave Tracker has been developed by Elexon Mining in conjunction with CRC Mining, Rio Tinto and Newcrest, to enhance critical monitoring in block caving projects where miners go beneath an ore body and undercut it.

This requires blasting a segment out from under the ore body, which removes the support for the rock that’s above it. As ore is removed, gravity pushes down fragments to the undercut area where it can be collected.

As miners are unable to see into the ore body, it is hard to predict ore flows and manage the mine.

But the Cave Tracker system is looking to change that through the use of beacons that are installed into the ore body. These wireless beacons can then be tracked in 3D by detectors as they move through the mine as the ore is drawn to the bottom.

Beacon prototype

The cylindrical beacons measure 76 mm wide and about 33 cm long and are made of fibreglass to withstand the harsh environment of underground mines.

But the first beacon prototype was not designed to survive the force of a cave but to test the locating technology. Instead, Elexon Mining had access to holes in a mine where it lowered the first prototypes down on rope and recovered them again.

“They weren’t exposed to massive forces like the ones we have now. The prototype was pretty simple and probably quite far away from what we’ve got now,” said Simon Steffen, product manager at Elexon Mining.

The initial beacons measured much wider at 135 mm in diameter, but due to constraints on mine sites and the cost of drilling holes of that size, the beacons were downsized to its current 76 mm.

The newest generation beacons comprise a spinning magnet, electronics for controlling the motor and a battery pack, which has a lifespan of up to 10 years.

“We had to make sure the forces of the rock in the cave didn’t destroy the beacon, its housing, the electronics and the spinning element. From a mechanical point-of-view, this was very challenging,” Steffen said.

Elsewhere in the mine, detectors are installed deep around the mine and can detect signals between 160 m and 210 m away. It then collects this information via a cable to a central system where the data can be stored and analysed.

The system also works in near real time, which enables operators to analyse if material is traveling down according to plan, is moving in an accelerated fashion or whether there are areas that aren’t moving. This insight allows them to optimise ore recovery and minimise waste.

The system also has flow-on effects that improve safety by detecting areas that aren’t moving.

“If [the mine is] not propagating to plan and the cave stalls … it can create what’s called an air gap, which means they extract material that’s broken but no new material is flowing down from above, which creates a void,” Steffen said.

“If the rock above the void collapses at some point, it can displace a huge amount of air, which can have critical safety implications.”

Software prediction

The system has undergone two trials – the first at Newcrest’s Ridgeway underground mine and the second at Rio Tinto’s Argyle diamond mine.

In the first trial, Elexon deployed a small number of beacons. A small number of issues were identified and resolved, while the second trial deployed a larger number of beacons.

“It was really interesting … to actually compare measured locations of devices in the cave with modeling software prediction. To get these lined up was really good,” Steffen said.

“Also, from a technology point-of-view, we were happy that the beacons performed really well. There were a few beacons that failed, which we expected as a first-generation prototype.

“The number of failed beacons was relatively small and we investigated potential causes, which we followed up. Now with the next generation, we’ll hopefully have resolved most of these issues.”

Some of those potential issues included a software bug, but Steffen said as the beacons can’t be recovered once they’re in the ground, it can be diffciult to see what actually happened.

Elexon Mining is now a semi-finalist in the Australian Technologies Competition, and the system is still currently running at the Argyle mine. Another a system is also scheduled to be delivered to Newcrest. Rio Tinto also plans to use it in its cave mining operations at Oyu Tolgoi in Mongolia.

“In the scale of the mining projects we are looking at, where costs and revenue are in the multiples of billion dollars, the economic value of [this system] is potentially huge,” Steffen said. “Even small improvements can have a big effect on the bottom line.”

[Image: Screengrab from the Cave Tracker video courtesy Rio Tinto, Elexon and CRC Mining]

This article was originally published by Engineers Australia. Original article can be found HERE.

China’s exponential growth has been driving the growth in the resource industry, but the country’s consumption of minerals is slowing. The resource industry is moving from a price driven expansion strategy to a cost driven business approach.

Controlling costs and risks is gaining importance during this cycle of the resource industry. This in effect is resulting in mining companies looking into innovative ways in which it can improve its extraction efficiency – especially in the underground mining sector. There is usually a higher cost involved in underground mining, when compared to surface mining. In order to replace low-cost surface operations, large-scale underground mass-mining methods are gaining importance. Underground mining, however, comes with its own set of technical challenges and uncertainties, as it is not easy to see what you are doing.

“We know that the ore body is there, but the question is, how are we going to extract it in a cost efficient manner and are we extracting the targeted ore body? Leaving ore behind and extracting low-grade material which originates from outside the targeted ore body, can have a massive impact on short-term profits and the mine’s net present value,” Elexon Product Manager Simon Steffen says. “Excessive ingress of low grade material is an important reason for underground mines being shutdown as operations have become uneconomical,” he adds.

The team at Elexon have identified the potential of maximising revenues and the issue of uncertainty, which exists in the sector. They have since been working on solutions to improve extraction predictability and efficiency. Underground extraction in low-cost caving operations is a field where decisions are based mainly on experience and intuition, as the rock mechanics are still not fully understood.

“The data that our solutions provide these mines enables the operators to make decisions based on facts and measurements, while improving and streamlining its processes,” Steffen says. “We are focusing on developing solutions for improving extraction efficiencies and economies which are based on rugged electronic systems that can survive the underground mining environment.”

The team at Elexon’s mission is to provide solutions, which will give the mines the right information at the right time necessary to exercise a large degree of control over the extraction process. The technology solutions Elexon has developed and are currently developing include, the Smart Marker, the Network Smart Marker, 3-D Smart Marker and the Cave Tracker. Over the next 6-months, Elexon is due to release its Networked Smart Marker System. Meanwhile, the Cave Tracker and 3-D Smart Marker System which is undergoing development, is set for release in about two-years. This growing suite of solutions will be highly complementary and will provide measured feedback about the critical areas of cave mining.

The Smart Marker System measures blast efficiency and reveals ore flow post-extraction, while the Networked Smart Marker System focuses on measuring real-time cave development and propagation. The 3-D Smart Marker System will allow for real-time, micro flow tracking, Steffen says, while the Cave Tracker will be able to provide the mine operator with real-time data about macro ore flow in an underground mine.

“These technology solutions are essential to the future of mining to ensure that operations remain feasible,” concludes Steffen.

The mining industry is in the dark when it comes to an in-depth understanding about the mechanisms of underground mining methods based on caving, however, there is a smart solution that is addressing the issue.

It is called the Smart Marker system, developed by Elexon Mining; a company with a strong focus on creating innovative value-adding solutions to assist mining companies to improve ore recovery performance in underground mines, with a particular focus on block and sub-level caves.

One of the big issues with caving is that you don’t see what you are mining; you only see the ore when it reaches the draw points where it is collected. The consequences of unplanned material recovery are ore loss and dilution, which both of have a significant impact on productivity, safety and profit.

“The Smart Marker has the ability to measure ore flow from underground mines electronically, in particular sub-level and block caving operations,” Elexon product manager Simon Steffen said. The Smart Marker system is a blast resistant, long-life Radio Frequency Identification (RFID) device that is installed in the ore body of sub level or block cave mines. “It transfers its unique identifiers (ID’s) to the Smart Marker System Readers when extracted with the ore by a Load Haul Dump (LHD) machine.”

The reader automatically detects, logs and time-stamps the Smart Marker detections as the Markers are extracted with the ore at the production level. The overall system collates both the installation and the extraction data. “The movement of the rock is analysed based on the Markers’ original positions and where and when they are extracted,” Mr Steffen said.

Major miner Rio Tinto played a vital role in the development of the Smart Marker system with Elexon. “We recognised the importance of this technology for our operations, so we were very keen to be involved,” Rio Tinto geotechnical engineer Andre van As said.

Meanwhile, before the Smart Marker, Rio used a “Dumb Marker” system, which was basically a piece of steel with an identification tag. “Unfortunately the recovery success was low,” Mr Van As explained.

Mr Steffen said it was important to understand what was going on in the cave, as the mining company faced potential risks economically if the project went off track. The Smart Marker system allows companies like Rio Tinto to not only improve its current mining operations, but future ones as well. “We have improved our predicted models based on the data we get from the Smart Marker system,” Mr Van As said.

The team at Elexon believes the Smart Marker system has the ability to bump up the output from an underground mining operation based on the insight it is able to provide. Aside from Rio’s Northparkes mine, the Smart Marker system is currently being used at mining operations in Australia, North America, Sweden, Chile and Indonesia.