A Hawk’s eye view

Hawk Measurement sat down with Australian Mining to discuss some of its most important systems for tailings management.

Tailings dams are built as earthen structures, and there are many factors that can lead to their failure.

The last 20 years have seen a marked increase in the failure of tailings, which has had significant consequences on the environment and human safety.

But the mining industry recognises this issue and is making major efforts to mitigate – and ultimately eliminate – the potential dangers.

One company that understands this pressing issue, and offers a range of solutions, is Hawk Measurement Systems.

Hawk Measurement has been solving solid- and liquid-related issues in several industries, including mining and mineral processing, for 35 years.

To help mining companies monitor tailings dams efficiently, Hawk Measurement developed the Praetorian fibre optic sensing (FOS) conveyor health-monitoring system.

“It started from a Melbourne Water grant who were having major pipeline leak issues,” Hawk Measurement fibre optic product manager Mathew Cook told Australian Mining. “I’ve spent five years taking that same sensor and adapting it to different applications.

“You can take the same fibre optic and stick it to a fence, which then becomes a smart fence that can detect intruders. We can also put it in a conveyor so it can monitor idler condition.”

The ORCA system was designed for the dewatering of tailings.

The FOS system looks after three key areas: acoustic/vibration/sound, temperature, and strain.

“We can do a combination of those three to monitor many different applications,” Cook said.

“We are currently working on solutions for tailings dams, so we’re putting fibres within the earthen structure itself and putting out information that geophysics can look at.

“It depends on the application, but the main pitch of the unit is that it completes linear asset monitoring – so any large object that’s roughly line-shaped or that you can draw a line around.”

An effective method of reducing failures in tailings dams is to monitor the strain within the dam’s earthen structure by putting the fibre in when various lifts are done.

“The basic concept is you can either put them in the lifts or boreholes,” Cook said. “You stick the fibre to something and then it will measure the strain on that – whether that’s a layer within the earth or the borehole, or whether you want to monitor just the ground structure or the layer.”

One of the FOS system’s notable features is the fact it doesn’t require any power or communications in the field.

“It’s totally immune to electromagnetic forces because it’s a light-based system. You can throw electricity, magnetism or radiation at these cables and they won’t react,” Cook said.

The system can also be placed in areas where it is unsafe for workers to be located, increasing safety of people as well as productivity.

“When talking about conveyors, we can monitor the historical condition of each idler or group of idlers, but typically each idler on the left and right-hand side, and we can watch that deterioration over time,” Cook said.

“When you’ve got enough of that data, you can start making smarter decisions and can schedule and target your maintenance better.

“The system is a machine, so it won’t get lazy, tired or distracted – humans are likely to miss things unless they’re really switched on. And if it’s something you do every day, you tend to be less vigilant and more complacent.”

The FOS unit requires no maintenance or calibration after commissioning.

Customers who have used the FOS system have been impressed with its reliability.

“You can potentially reduce the amount of downtime you have in a particular shut down for a particular belt,” Cook said.

“Some belts are quite valuable in that respect, especially if they feed your point of transfer.”

In addition to helping mining companies monitor their tailings dams, Hawk Measurement also has a solution for controlling tailings thickeners, the ORCA sonar bed level system.

“(The ORCA system is) a lower frequency sonar. It was designed for dewatering of tailings and can typically be used in concentrate thickness,” Cook said.

“The vast majority of what it’s trying to do is allow control of thickener and you can go to an automatic control-based system.

“It was specifically designed to be more rugged. It has an auto-cleaning function, so it dips into the water and that shearing action prevents like scumming and build-up.

“It works in thickeners where you’ve got a lot higher density materials suspended in the column.”

One of the biggest problems mining companies face with tailings thickeners is the fact they can get into an uncontrolled condition and can be slow moving in their responses.

“You can put (the ORCA) system in there, take a couple of feeds from other bits of information you have, and you’re able to control the thickener and keep it stable,” Cook said.

“You can very slowly go to an uncontrolled condition and then will need to overclock the tank or add too much chemical to try and get the material to settle out.

“You can do all sorts of things to effectively deal with the problem, but those things can be incredibly expensive.

“The idea with the ORCA is that it maintains and gives you an output that you can then make very small micro adjustments to. For example, you don’t want over height settling bed in the bottom of the thickener.

“With the settling layer, you can predict when you’ll start losing material by maintaining and keeping it controlled with very small but consistent doses of flocculent.”

Since its inception in 1988, Hawk Measurement’s bread and butter has been primary level solutions for a wide range of industries.

“Hawk has always focused on not necessarily going down the path of having a million features but trying to get the strongest and best return signal we can from the primary sensing element,” Cook said.

This feature appeared in the November 2023 issue of Australian Mining.

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