The company is noted for the imagination of its mining solutions and it shows no signs of slowing down. Next on the agenda? 3D printing. Ewen Hosie writes.
Columbus Group in not a company known to rest on its laurels. The engineering firm has won three Australian Mining Prospect Awards in five years — one for Innovative Mining Solution in 2014, another for Minerals Processing of the Year in 2015 and a third for Excellence in Environmental Management in 2017.
Columbus Group’s initial win came for its 3-D ‘down-the-hole’ (DTH) high-pressure water drilling system. Although this was not the first water drill on the market, it was regarded as innovative due to its digitally-controlled manoeuvrable cutting head, which gave the enduser more freedom in terms of directional control. The system in turn delivers an increase in efficiency and dust suppression.
It also separated itself from similar fracking equipment. Instead of pumping high-pressure water down to the cutting head, it pumped medium-pressure water to an ultrahigh- pressure pump onboard the cutting system, providing improved distribution and alleviating the potential of sediment damage.
Installed with the subtractive drilling system is a very flexible additive 3D printer. While drilling and cutting large cross section fissures, it can produce its own solid bore casing, conduits for underground services, and even a cotton wool-like 3D printed fill material to allow more water, oil and gas infusions.
The 2014 win was backed up the following year with the company’s Water Wall system, which cuts solid rock into tetra- and octahedral shapes for direct feed into processing mills without requiring primary crushing or explosives. Columbus made it a hat trick in 2017 with a Prospect Award for its methanolic conversion of sugar-like carob tree pods using a bioethanol-producing bacterium.
The company has built on each of these technologies since the 2017 win, while also introducing other new innovations. Columbus Group’s chief executive officer Donald Yates says the company has moved more strongly into additive 3D printing and subtractive manufacturing in the same machine.
Initial research and development on carob pods focused on their conversion into methanol fuel cells for transport electricity. However, the carob’s lactic acid can also be used for conversion into polylactic acid (PLA), which is then utilised for filament for 3D printing.
By using carob pods in this way, mine sites could be granted a useful material source for additive manufacture of spare parts. This even indirectly extends to the creation of metal parts through a process called lost PLA casting.
Using this process, a metal part requiring replacement is 3D printed using PLA. The PLA copy is then covered in plaster or casting sand, with the PLA melted away and recovered to make a mould that is used to shape a new metal part. This, therefore, avoids the downtime and cost issues associated with having to wait for the shipment of new parts.
“The carob pod is a sugar-rich legume and it’s an all-year tree; it’s as tough as old boots,” Yates tells Australian Mining.
“What we’re working on at the moment is something about the size of a refrigerator where the carob goes in one side and you get PLA filament out of the other. “So what you can do on your mine site is 3D print a spare part that you need, like a cutting jaw or something like that; you pack it up with casting sand, melt it so the PLA falls out then you can fill it up with your casting material.”
Yates says the process has ancillary benefits outside of machine part reproduction. For example, if a mining company has a catering department, it can specify if the plates, cups and wrapping consist of PLA plastic.
The products can then be chopped up and stuck in the same machine to make filament. They can also make plates, cups and other items out of the PLA.
Columbus has likewise taken the step to modify its Water Wall system with additive technology as well. The design’s original purpose was to cut solid surfaces, such as rock walls, in small shapes so the resulting slurry is pumped straight to a semi-autonomous grinding (SAG) mill, bypassing the need for conveyor belts, trucks, loaders, explosives and production drilling.
It is a technology that is reductive by design. However, Columbus has recently modified the Water Wall system with additive technology that allows the machine to both cut away and print material with “virtually the same cutting head” using mixtures of PLA, fibre, and ultraviolet, fast-setting smart resins.
The construction and reinforcement of tailings dams is a practical example of a situation where this technology will be used. The company’s DTH high-pressure cutting system that won the 2014 Prospect Award has more potential 3D printing applications as well. The printing of earth movement compensating concertina piping for increased flexibility, and Columbus’s Squeezable Sponge Piping, which captures and then harnesses stormwater for distribution into the soil, are two opportunities the company is targeting.
The water would be extracted from the piping by twisting, using shape memory alloy (SMA) or compressed air from the surface. When used on tailings dam applications the cutting system even weaves fibre-reinforced 3D printed netting inside the facility’s walls for added reinforcement.
“If the cutting heads are heated then you can squeeze the adhesives in the mix through them without any grief, but once they get into tailings dams for example, it’s usually not running at 200–300 degrees Celsius; it’s out in the sun at a maximum of maybe 50 degrees Celsius,” Yates says.
“The Water Wall technology that won us the Prospect Award in 2015 has seen us basically change the cutting material to a 3D additive material that is temperature sensitive and that gives it the fluidity at a high temperature so it can be placed where required.”
Columbus Group has also been using the Water Wall system to cut through disused electronics such as old televisions buried in rubbish tips from the changeover from black and white to colour, or more recently, CRT to flatscreens. These older televisions are rich in copper, which can be extracted and reused.
“Because tetrahedral and octahedral shapes are solid by their very nature, when you mix them together and put them back into whatever you’re making, they form a solid shape again with virtually no airspace,” Yates explains.
“Normally we just use garnet and ultra-high pressure water to facilitate this.”
This technology extends to mining infrastructure applications, such as rail track extensions and the development and repair of new and existing underground and open-cut haul roads with built-in guidance and power transfer points.
“You can basically print the road as you go, including rumble strip. The 3D software determines the road mix so you can just rebuild the road as you go,” Yates says.
“You can even add paint to it so the dotted lines and magnetic guidance inserts are put down as part of the single pass process as well – it’s all done in one efficient operation.”
It seems oddly fitting that Columbus Group would elect to build on its mining technology for road building in this fashion. It is, after all, a company that has long been comfortable with forging its own path.
This article appears in the April 2019 issue of Australian Mining.