Drilling deep

As the mining industry seeks to improve extraction rates, the need has grown for improved drilling methods. Michael Sheffield writes for Australian Mining.

As the mining industry seeks to improve extraction rates to access an estimated A$600b in metal value contained in known but currently sub-economic deep hard-rock reserves, the need has grown for improved drilling methods. Michael Sheffield writes for Australian Mining.

At Sandviken, Sweden, on 8 December 1848, five years and five days after the barricades fell at Eureka, an event took place that would lift the world out of the Iron Age and into Steel Age modernism.

Göran Fredrik Göransson’s production of steel using the Bessemer method enabled a quantum shift in industrialisation. And in revolutionising rail construction, ship building, civil development, building construction and armaments manufacture, world demand for iron ore, coal and limestone would produce a revolution in mine technology, starting with the mechanisation of rock drilling.

Steam powered mechanical rock drills, using steel bits produced by Göransson’s company, later to be renamed Sandvik, became available during the 1860’s. The days of tap and hammer mining were over.

Australia had its early adopters. Hunters Reef company at Bendigo operated a locally—invented rock drill in 1869. But, as Geoffrey Blainey, notes in his mining history classic, ‘The Rush That Never Ended,’ “Australia, with its host of small mines, tended to be slow to adopt rock drills. They were heavy and cumbersome, had to be shifted before the holes they drilled could be fired, and they often broke down”.

In 1891, Swedish manufacturer Nya AB Atlas (New Atlas Company — rebirthed after the collapse of AM Atlas in 1890 ) expanded beyond steam engines and steam locomotives into pneumatic tools (riveting hammers and drills in 1901) compressors (1904) and rock drilling equipment (with its first rock drill in 1905).

Compressed air tools were to carry the company forward, and in 1952 Atlas gave the post-war mining world ‘The Swedish Method’ — a rock drill light enough for one man to operate, with pusher leg and drill steels with tungsten carbide drill bits and a penetration rate of 8-10 m/hr (drill metres per hour per operator), double that of its 1928 RWT-80 model and three times the 3-5 m/hr capability of its 1907 Cyclops 50.

Exponential productivity gains continued through to the end of the century. The Boomer range doubled and then trebled output from 65 m/hr to 180 m/hr between 1962 and 1983. By 2005, three generations of Rocket Boomers had lifted the bar to 450 m/hr.

In the 1970s at Kalgoorlie, Bill Metske and Jan Humphries applied thinking from the U.S. oil industry to equip DTH (Down The Hole) Hammer drills to retrieve uncontaminated samples from open hole drilling in virtually any geological setting, with improved penetration rates and significant cost improvements.

Reverse Circulation Drilling was an immediate success. WA alone clocked up more than two million RC-drilled metres per annum in the late ‘80s and, as Fredrik Gabrielsson, Product Manager, Reverse Circulation, Atlas Copco Secoroc, says “RC drilling is now the most common method used for surface mineral exploration drilling throughout the world”.

Drilling is as integral to mining as sweat. But because it accounts for a relatively small percentage of total costs — 20% of development and 10% of production costs — it has not caught the imaginations of mine owners as a fertile field for research and development investment.

That is not to say that drilling is taken lightly. It may be one of the industry’s most commonplace activities but is also respected by many as an art form and its challenges have been understood widely enough to ensure that it has not been seriously proposed as a soft target for automation.

Consequently, drilling has developed an entrenched image as a trade service whose management and development is best left to those with specialist skills in the area – a service best left to specialist contractors.

Accompanying that has been the tacit expectation that, despite labour and capital equipment supply constraints, with the rigours of the procurement process containing cost increases, there should be no reason to believe that current drilling technologies and methods might not be scalable to the levels needed to meet forward demand.

Not so says academia and the CSIRO. And an increasing number of highly informed industry members agree.

The worm has turned and some of the nation’s largest mining house now acknowledge that the time has come to integrate drilling more fully in a vision of a future era in which mining production is as scientifically informed and enabled as metallurgy has become over the last 20-30 years: An era characterised by the convergence of mining production as the application of trade skills, intellect and the imposition of collective will on the nation’s ore bodies with new developments in Information Age science and technology to establish the competitive capabilities needed to secure the industry’s future, and the future of a nation dependent now as perhaps never before on the global competitiveness of its resources sector.

That kind of thinking is reflected, in process terms, in BHP Billiton’s holistic approach to the use of down-the-hole geophysics and other objective, sample-based scientific information to produce the “high-grade products … that our customers desire” and “meet (their) demanding and constantly changing tonnage requirements” through “a highly integrated and tightly controlled process that begin as early as the exploration phase and ends with the final blending of products as thy are loaded into ships at the port”.

Under that approach, “Ore types and their physical and chemical properties are identified during exploration and ore body modelling. Mine planning and the mining sequence are controlled to extract ore of the characteristics and in the quantities that are required to produce the final blended products,” the company says.

Beyond this, the application of this thinking in the development of a new generation of intelligent, automated mining equipment is seen in the CSIRO’s aspirations for research being undertaken in the ‘Transforming the future mine’ stream of its ‘Minerals Down Under Flagship’ program which focuses on ‘Enhancing knowledge from drilling’, ‘Geologically intelligent surface mining’ and ‘Non-entry underground mining’.

In the drilling area, CSIRO is committed to “design, test and deliver to market new and effective drilling and logging technologies” that will support the development and delivery of a “revolutionary drill rig” which will “significantly reduce drilling costs, increase rates of exploration, provide a greater quantity and quality of data acquired from bore holes and improve the control of rock fragmentation”.

What is needed, says Jock Cunningham, CSIROs Theme Leader — Transforming the Future Mine, is “a transformation of the way that drilling happens — in analysing information from within drill holes and in the way that we make the drills that produce those holes.

“In addition to new ways of drilling, we need to equip ourselves to surface mine in logically controlled machines, that is, in machines that can sense the geology in which they operate, and then pass that geologically-based information back to allow mine design to be updated and kept current, to allow the mine plan to be changed and modified, and to allow new instructions to be issued to the mine machine.

“This would allow us to close the loop on mine design and machine operation, it would allow the designers and mine planners to work very tightly with the production people, and it would allow us to do that by long-distance remote control,” he says.

Will this happen?

The good news, Mr Cunningham says, “is that we have seen a change in industry expectations. Some very senior people in our larger mining companies are now willing to, and wanting to change the way that they operate mines. It’s one thing to have researchers at universities saying ‘why don’t you do this’ — or, indeed, to have them engaged in that work — its something else again to have a customer base which shares that same vision”.

What has delivered that shift?

“I think it’s because there is an awareness that we are reaching the limit of our ability to secure the future by scaling up conventional technologies. The other aspect is that it is increasingly difficult to find people to send out to our remote mines.

“This is a recognition of the need that exists to equip our people to perform the tasks that must be undertaken to Australia’s world-leading industry standards in the demanding conditions under which they must operate. It is also a recognition of the need to develop smart machines that can get people out the hazardous spots where they should not be, and the nasty jobs which they should not be doing, in the forward-looking workplace that we should be creating,” he said.

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