The mining industry is turning to water power to increase the efficiency and effectiveness of underground drilling.
The exploitation of narrower ore deposits situated at greater depths below the earth is increasing the technical difficulty of mining operations, and large-scale drilling in particular.
Drilling technology must be capable of tapping deep, narrow deposits in a manner which is quick and economical, as well as environmentally friendly and safe.
In order to meet these exacting demands, Swedish mining engineering firm Wassara has developed water-powered drilling equipment which has already been extensively deployed at iron ore operations by parent company LKAB.
Wassara’s system is applied to blast-hole drilling and uses water to power a down-the-hole (DTH) percussion hammer in lieu of the more commonly used air-powered DTH, top hammer or core drilling equipment.
Wassara’s patented DTH hammer uses 300 litres of water per minute to produce high frequency, high energy blows which are capable of achieving pressures as high as 180 bars.
The incompressible nature of water results in greater efficiency and effectiveness with respect to power transmission, enabling the technology to be deployed in areas where other methods would be difficult to apply. It also dispenses with the problem of power loss via the drill string, which is characteristic of top hammers.
This advantage means the water-powered percussion hammer can operate with a high level of efficiency at just about any bore length, from anywhere between 10 metres in depth to a full kilometre. Wassaras’s water-powered hammer is also suitable for bore hole sizes ranging from 60 to 254 millimetres.
Wassaras’s parent company, mining outfit LKAB, has upscaled production by around 800 per cent using the DTH hammer, which has enabled them to drill long, straight holes for great reduced cost.
LKAB has already used the water-powered drill to create more than 18 million metres of drill holes. The resulting holes are both long and straight, with minimal deviation and improved quality.
This results in an ore which is thoroughly fragmented subsequent to blasting. When the water leaves the hammer, it also emerges with sufficient velocity to convey any debris to the surface, producing a clean passage which facilitates subsequent operations.
LKAB has used the water-powered DTH hammers to increase borehole depth from 28 to 56 metres at its Kiruna mine. The hammers also raise the outcome from each blast from 1,200 tonnes to 10,000 tonnes.
The use of water and the attendant increase in efficiency is also beneficial for the environment and the health of operators. The use of clean water dispenses with the need for oil additives, thus preventing the creation of an oil mist and dust particles, while the heightened efficiency of the system results in the use of a mere quarter as much energy as air-based drilling systems.