Underwater mining on land

Waste not, want not

A new robot system will reopen abandoned, flooded mineral workings

Teeth in its head and a sting in its tail

THE IDEA of underwater mining is not restricted to the ocean floor (see article). High water tables submerge many terrestrial deposits, too. At minimum, this means doing a lot of pumping to make them workable. Sometimes, it makes those deposits altogether inaccessible. Flooding also adds to the cost of re-opening closed mines. The team behind VAMOS hopes to do something about this.

The Viable Alternative Mine Operating System, to give its full name, is being developed by a consortium of 16 European firms and research institutes. It is currently on trial at Silvermines, Ireland—which, as its name suggests, was once home to workings for silver and other metals. They are now closed and flooded. But one of them, a source of baryte, the principal ore of barium, has been repurposed as VAMOS’s test bed.

The core of VAMOS is a pair of remotely controlled vehicles. These are floated on-board a special platform into place over the site to be mined, and then dropped through the water (to a depth of 57 metres in this case) by a crane.

The larger vehicle is a 25-tonne tracked robot (pictured) with a powerful rock-cutting head at one end and, at the other, a hydraulic gantry that can carry tools such as drills and grabs. Crushed ore-bearing rock is pumped to the surface through a flexible pipe, and a cable carries power and data between the robot and an onshore control centre.

The smaller vehicle is called EVA. It has neutral buoyancy and swims around the mining site. It was designed at the Institute for Systems and Computer Engineering, Technology and Science, in Portugal. EVA first makes, and then continually updates, a 3D map of the area—transmitting this cartography to the main vehicle, to assist navigation.

Both vehicles use sonar, cameras and laser rangefinders to work out where they are. They send these data to a pilot in the control centre, who sees them displayed on a multi-screen console of the sort gamers can only fantasise about. A future version may also be able to analyse the ore spectroscopically as it is mined, enabling rich seams to be pursued and poor ones abandoned.