The long-standing use of water to cool underground mines is increasingly providing the opportunity to apply the free water pressure head that this offers to energise mining equipment.

High-pressure water technology, a proudly South African technology, has advanced markedly over the last couple of decades, turning South Africa into a global leader in water hydraulics for mining.

“From humble beginnings back in the 80s, high-pressure water power has gone mainstream,” Hydro Power Equipment (HPE) director Ulrich Kienle told Engineering News & Mining Weekly in a Zoom interview.

Some 50 different mine sites are using water hydraulics as the primary powering medium to drive rock drills and mining machines and equipment can be configured into delivering any kind of mining solution using high-pressure water power.

Several mines on the Northern Limb of the Bushveld Complex have even integrated modern trackless mining equipment with water hydraulics for doing board-and-pillar bolting activity – “a very interesting example of how you can fuse modern water technology with sophisticated trackless equipment”, said Kienle, who sees water energy as the opportunity for the South African mining industry to ensure longer life-of-mine and do things in a better way for the benefit of all stakeholders and society at large.

Amid the Eskom power crisis and the need for sustainability, water hydraulics is on the receiving end of unprecedented recognition: “We’re beginning to have the kind of conversation with the mining industry that even a decade ago was not possible because the urgency just wasn’t the same as it is today,” said Kienle.

“We live in a world today where sustainability, green credentials, decarbonisation are all big issues. Being able to use less energy to produce an ounce of gold or a ton of rock, and being in a position to not contaminate the environment, or precious water resources, means you’re doing things in a way where the principles of ‘use less, don’t contaminate and reuse’ are a given with water hydraulic technology.

“We’ve run a number of long-term production trials with some of the mining majors in both the gold and platinum space and had these trials independently reviewed by third-party consultants that have put all sorts of measurement devices on to the water lines, and water ticks all the boxes,” said Kienle.

Engineering News & Mining Weekly: What opposition does mining with water face in water-short South Africa?

Kienle: It’s one of those myths that we’ve worked really hard to dispel. At face value, people always say, mining with water in a water-scarce country, does it really make sense? The answer is an absolutely categorical ‘yes’. Water hydraulics are efficient, they get the job done quickly; whatever water you have as a footprint on a mine site, that water is simply pressurised. It is then utilised and comes back out of the mine with the process continuing in a closed-loop cycle, with some losses to evaporation.

How financially competitive is high-pressure water power?

This is one of the big surprises. Initially, when water hydraulic technology was developed, it was quite expensive. Over the years, economies of scale have come into play and the technology today is surprisingly affordable.

Water Hammer Technology

Building blocks are available that are configured into a mining solution using water power.

“Those tools all exist. What we’re particularly excited about are the latest developments. The first is what we call the Isidingo drill, which is in commercial use at six of our South African mines. We have combined it with a drill guide that allows us to deliver precise drilling and, as miners will tell you, good drilling makes blasting easy and good blasting means that you get maximised rates of advance and production. It also uses much less water than prior generation water drills.

“The second is about man-free boxholing. It’s really quite clear that putting human beings into boxholes is perhaps an unsafe thing to do and the industry is starting to move in the direction of doing it man-free.

“We do this with what we call in-the-hole water hammer technology and we’ve broken all the records in delivering excavations in excess of 100 m. This has never been done before with water hydraulic in-the-hole technology.

“We’ve just finished on a mine site 102 m long and are now in the process of blasting. We have also used this technology to do drilling in a diamond mine, where we’ve managed to get these holes to go up in excess of 200 m.

“The last example is that we’ve also managed to integrate this hydro technology with trackless mining technology,” Kienle enthused.

Hydro Hoisting

On the horizon is hydro hoisting, the concept of putting whatever rock is produced underground into a pipe and bringing that pipe to surface to fulfil the vision of using the pressure and the coolth of water hydraulics to power equipment, lubricate equipment, cool equipment, and then use that flushing water to take broken suitably downsized and piped rock to surface to achieve rock-on-tap.