The 10th International Conference on Acid Rock Drainage and the International Mine Water Association’s Annual Meeting, ICARD-IMWA 2015, was held in Santiago, Chile from April 21-24.
Over 400 delegates from 31 countries attended to hear 186 presentations. The conference, organised by the South American Network for Acid Prevention (SANAP), and the company Gecamin, was chaired by Robert Mayne-Nicholls, CEO of Minera Los Pelambres. The Co-Chairs were Terrence Chatwin, Technical Manager of the International Network for Acid Prevention (INAP), and Adrian Brown, President of IMWA 2013. ICARD is the world’s leading event in acid rock drainage that takes place every three years.
The themes of the conference spanned materials characterisation and prediction of AMD, management of waste through operations and closure, passive and active treatment of mine water, surface hydrology and groundwater hydrogeology. One aspect of special relevance was approaches to scaling from the results of laboratory tests to field scale. This is of major import given the many orders of magnitude of mass (and particle size) that are represented as test methods progress from finely ground pulps through to the masses and particle size dimensions of full scale waste rock dumps.
One session of the conference was dedicated to national ARD guides and programs to improve the performance of AMD management. Of especial note in this context is the Canadian MEND (Mine Environment Neutral Drainage) program. This has been running since the early 1990s and continues to be a world leader in advancing the science and technology of mine waste management. As noted by the ICARD-IMWA 2015 Technical Coordinator, Jacques Wiertz, ‘The amount of money Canada has saved by implementing this program is really remarkable. We’re talking about billions of dollars in savings as a result of these solutions.’ Australia has a lot to learn from the MEND program and the National Abandoned Orphan Mine Initiative (NAOMI) on how that type of model can be effectively developed and applied in this country.
The proceedings of the conference can be purchased online at www.gecaminpublications.com.
Conference field trip
The field trip on the Saturday after the conference was to the Los Pelambres mine (pictured) located 200km north of Santiago. This mine produced 405,000 tonnes of copper in 2014. To put this output into context Chile, which is the world’s biggest exporter of copper, has a total annual output of around 5.8 million tonnes. The porphyry copper mineralisation at Los Pelambres comprises a resource of 3000 Mt of ore grading at 0.65% Cu with molybdenum, gold and silver and credits.
The open pit is located at 3200m above sea level and has a top plan footprint of 2.5 x 2.2 km at surface. All attendees on the field trip had to pass a medical screening at lower altitude prior to ascending to the level of the mine. Given the size of the resource there are still several decades of production remaining before closure. AMD is a risk factor given the sulfide content of the waste. The mine is located in the headwaters of a river that flows down the valley to a predominantly rural agricultural community. Hence management of the snowmelt runoff that occurs at the end of winter is a significant issue.