In June, I left the safety of my desk in Montreal for the wilds of Sudbury, Ontario. I was there for MassMin
, to hear from experts and to deepen my knowledge of mass mining. From engineering challenges to HR conundrums, I heard about problems and solutions emerging as miners turn to larger, lower-grade deposits underground. Here are some lessons I brought back:
1 Surface mining giant digs deep to build business In Allan Moss’ plenary talk, I learned Rio Tinto predicts getting 43 per cent of its copper production
from underground mines by 2021. Since the company began work on Oyu Tolgoi, a combined open pit and underground gold-copper-ore mine in Mongolia, it has
developed an underground technology centre with the Centre for Excellence in Mining Innovation. Moss’ presentation made me realize how massive a change
mass mining represents for the industry.
2 El Teniente’s layout copied worldwide One of two layouts considered for the extraction levels of contemporary block caves was pioneered at Codelco’s El
Teniente mine. El Teniente and the other most common style, herringbone, both have pros and cons. El Teniente layouts are best in mines with large
footprints, but aren’t well-suited to use of electric loaders. Some mines can transition between the two layout styles, depending on how mining progresses.
As the El Teniente layout is well-suited to larger cave mines, it is gaining popularity.
3 Archived mass mine designs still valuable There are only about ten mass mining projects operating worldwide, but around 40 in development. Engineers have
few working examples for designing new projects. As highlighted by Jarek Jakubec of SRK Consulting Inc. in his talk on incline cave mining, there are ore
bodies that are not economical to mine with commonly used designs, but there are options. Although there are no operating incline cave mines, projects over
the past 20 years can act as a resource.
4 Bigger mines mean more money down Today’s mass mines extract low-grade ore, so must be huge to be economical. Mass mines can have over 2,000 drawpoints on
their footprints – each costing about $500,000 to construct – which I learned chatting with AMC Mining Consultants. As drawpoints need to be established
before revenue can be generated, securing enough investment to get mines built is more difficult than ever.
5 Killer commutes simplified with computer models Transporting staff to a mass mine is a huge challenge. At Freeport McMoRan’s Grasberg block cave there
will be 4,000 workers underground at any one time. According to Chuck Brannon, manager of underground mine planning at Freeport McMoRan, moving thousands
of people, as well as several hundred thousand tonnes of rock, per day requires large-scale and long-term planning. Computer models can predict where
bottlenecks might lie at all stages of development.
6 Underreporting of accidents elevates risk At Iain Ross’ talk on major hazards in block caving, the engineers all seemed to agree: The recorded number of
very dangerous incidents (like air blasts) is far less than the true number observed in the field. If engineers lack accurate statistics from operations,
it becomes difficult to learn from mistakes, and proliferation of risky techniques can become the norm. This represents a significant risk, given the very
few examples of operating mass mines available to draw on.
7 The “ore factory” – new technology may improve efficiency by 600 per cent Jens Steinberg of Caterpillar says potential efficiency gains in continuous
underground cave mines are in the order of 500 to 600 per cent. To achieve that goal, Caterpillar has carried on Bucyrus’ continuous mining project, Block
Cave Mine 2020. The system will be fully automated and use a continuous miner or roadheader in the undercut. The company proposes to automatically push ore
onto an interconnected system of conveyors. Sensors would be used to detect where the conveyor belt has room for more, continually producing ore with
minimal human involvement.
8 Ask equipment suppliers for help – they have experience on the ground I was impressed by how much knowledge folks from Sandvik and other equipment
manufacturers had to share. Around the lunch table, it became clear that involving those most familiar with equipment at a project`s inception phase can
help smooth construction and operation. Many equipment manufacturers have advanced engineering teams that have already experienced, and can predict,
problems new mines may face.
9 Less can be more when it comes to simulation Using 3D simulation has its benefits, but there are times when it is too complicated, too time consuming or
too costly. Troy Newman spoke about how Rio Tinto used 2D Arena simulation tools for the feasibility study of the Oyu Tolgoi project. And Patricia Rojas
from Vale was impressed that the 2D tools were so effective. Ultimately, the most appropriate tool is the one that does the job best.