Digital underground
Written by: Philip Mason | Published:

Philip Mason digs into the communications technology currently being used by mining companies to maximise profits and keep their workers safe.

While perhaps not regarded as ‘mission critical’ in the same way as more public-facing sectors such as community safety or air travel, mining still takes place in a dangerous environment, where mishaps can easily lead to disaster.

This danger lies in the nature of the work, which in the case of underground mining often takes place hundreds of metres below the surface. One of the most well-known incidents that serves to highlight its dangers was the plight of the 33 Chilean miners who became trapped half a mile under the earth and rock following a cave-in at a copper and gold installation in 2010.

Certain features of modern mining technology coupled with the sheer scale of the endeavour have also increased the vigilance required on the part of those who make their living underground. In a disagreement between a human being and a 300-tonne haulage vehicle, after all, there is only going to be one winner.

As well as safety challenges, the mining sector also has to find efficient and effective ways to communicate with those working on-site, and for them to communicate with each other.

This is no straightforward task, with the type of mining – for instance, coal, iron ore, cobalt, etc – in large part dictating the propagation of any radio signal. The enormity of a typical site, whether underground or open-cast, also means that companies have to find ways of guaranteeing coverage across thousands of metres in all directions.

Many of these concerns are addressed by Rajant’s multi-point ‘mesh networking’ system, which has become widely used across the sector.

No single point of failure

The Rajant system operates via a series of ruggedised radio node units, which the company refers to as ‘Breadcrumbs’, and across a broad range of radio frequencies. For example, its four-transceiver LX5 product works in the 900MHz, 2.4GHz and 5GHz bands. The units are designed to guarantee low-latency connection, with the data – via what the company calls its ‘Instamesh protocol’ – routed across the site in question in the most efficient way available at any given moment. These nodes can be deployed individually or mounted on pre-deployed equipment, such as the aforementioned 300-tonne haulage vehicle.

Giving an overview of their functionality, and why he believes they are so well suited to the sector, Rajant’s director of sales for EMEA Chris Mason says: “There are several key principles on which the system is based, with a crucial one being that the data connection simply does not break.

“Because Rajant radios operate on multiple frequencies within each individual breadcrumb, it mitigates any possible interference that might be occurring locally. If any difficulty is encountered on one frequency, the radio automatically uses an alternative with no single point of failure.”

He continues: “This is important because modern-day mining takes place around the clock, so naturally the communications network has to be functioning all the time as well. The node checks 20 times a second to see which is the fastest route for the data to get off the network to the wired environment.

“The system is also highly scalable – the signal doesn’t degrade no matter how many nodes you add. Line-of-sight connectivity between network nodes is around three kilometres.”

Copper, molybdenum and sulphuric acid

As well as being a habitually dangerous endeavour, mining is also a daunting one from an organisational and logistics point of view. This is well illustrated by one of Rajant’s main clients, the Rio Tinto-owned Kennecott facility in Utah, which is one of the most important installations of its kind in the United States.

Two and three quarters of a mile wide and three quarters of a mile deep, the 114-year-old open-cast mine supplies around seven per cent of the country’s copper, as well as other materials including molybdenum and sulphuric acid (the latter as a byproduct of the smelting process). It is, according to Rio Tinto, the largest man-made excavation on Earth.

Regarding the mining process itself, the site’s operators use explosives to extract the ore – no walk in the park in itself – which is then transported by massive haulage vehicles to a crusher.

This processed material subsequently travels several further miles by conveyor belt to a machine known as the ‘concentrator’, where it is mixed with an aqueous solution and ground into fine powder. Having been made into concentrate, it then moves another 17 miles to the facility’s flash-smelting furnace.

Discussing the part Rajant technology plays in the process at the Utah facility, Mason says: “We’re currently being used for things such as mapping the location of the machinery in and around the site. We can also help monitor the alertness of drivers and operators, for instance by looking at the number of blinks within a certain time period.

“The top mining companies are now using this data – harvested in real time via the use of onboard sensors – to improve performance in a predictive way. Looking in particular at questions around where a vehicle spends its time, we’ve seen organisations show between a three and 10 per cent improvement in yields.”

According to Mason, one particularly important area is the use of data to keep track of and manipulate the vehicle maintenance cycle. This has seen operators move from a ‘time based’ model to a ‘predictive’ one, in which vehicles are brought in as and when necessary, even if they are not scheduled to go offline.

This may seem elementary, but it would not have been possible without the deployment of cutting-edge digital communications technology to monitor potential issues in advance.

“The mining process is a really interesting mixture of extreme civil engineering, coupled with just as extreme IT and technology,” says Mason. “They literally have to move mountains, so any advantage that can be gained during that process – as long as it’s cost-efficient – will be welcomed.

“With that in mind, there’s a sense that companies are now looking to roll out autonomous drills and trucks, with trials currently taking place across the sector. Human beings require time off, health insurance, pensions, wages and so on, so it
would be no surprise if companies try to take them out of the equation altogether.

“Also, if someone gets hurt, production has to temporarily come to a halt, which is immensely costly. Mining is [always] going to be an inherently dangerous business.”

It’s still good to talk

It is clear that the mining sector is becoming increasingly reliant on real-time monitoring and automation, facilitated by solutions such as Rajant’s mesh networking system. Those working
on-site still need to speak to one another, however, something that continues to be accomplished mainly through the use of two-way radio.

One of the major players in the supply of DMR to the industry is Tait Communications, which recently kitted out the coal-producing Bengalla Mining Company in New South Wales, Australia. According to the company, its task was to provide a system that would eliminate what it refers to as ‘black spots’ at various points around the facility.

Speaking of the background to the roll-out, a Tait spokesperson says: “The previous system created a number of frustrations for the operators of the mine. It’s an open-pit operation, which meant a continually changing landscape due to the accumulation of ‘spoil dumps’ [waste material such as rock, which is produced during the mining process]. These interfere with the radio transmission.

“Health and safety was also a significant concern for the company, because of its use of blasting. For the new system to be a success, the mine required the capability to notify everyone on the network of any activities using explosives.”

To fulfil the brief, the company installed a multi-site VHF simulcast channel – a product known as the GS2 – thereby enabling the broadcast of identical voice information simultaneously from all sites across the network. This meant in essence that anyone on the system could travel anywhere within the coverage area, without having to change channels to take account of interference.

Speaking of the continued use of voice as an adjunct to increasingly ubiquitous mesh networking systems, Rajant’s Mason says: “There is still a huge amount of standard PMR-type radios being used in mining environments, something which is primarily a safety consideration.

“Our radios have an inherent TROIP [tactical radio over IP] function, which enables voice to go over the network through the use of a USB headset and microphone. At the very least, however, operators will also want a second, independent voice network just for resilience’s sake.”

Mining is a fascinating sector, within which safety concerns are intrinsically linked to imperatives around efficiency and profit maximisation. At the same time, it is also being transformed through its deployment of sophisticated digital and analogue communications.

As in so many sectors, only time will tell where this technology will leave human beings in 10 or 20 years. In the meantime, however, its continued use will help this vital industry run as it should, and that can only be a good thing.

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