Geoscientists focus on acid mine drainage

With the addition, in recent years, of hydrogeology and environmental geology, the Earth Science Department of the University of Waterloo has become the largest such department in Canada.

It is only fitting, then, that about 160 of the nation’s leading geoscientists should have gathered there recently to discuss advances in the understanding of the oxidation of sulphides in mine wastes and chemical alteration related to orebodies.

Two short courses were held prior to the combined annual meetings of the Geological Association of Canada (GAC) and the Mineralogical Association of Canada (MAC).

About 60 people — mainly government and university geoscientists — attended the MAC-sponsored course on mine waste, whereas about 100 people from industry, university and government attended the GAC-sponsored course on alteration.

With some 15,000 hectares of active mine tailings in Canada, local ground waters are in danger of becoming contaminated, which explains why environmental geology has become the fastest-growing area of study in the earth sciences, said Dr. John Cherry.

Many geoscientists present expressed confidence that companies will benefit from a greater understanding of the complex chemical and biological reactions that occur when sulphide minerals are brought to surface by mining. In particular, companies will know, with greater certainty, whether they are required to post short-term or long-term bonds to finance plants to treat acid mine drainage.

Presentations at the courses were made by researchers from several institutions, including the University of Waterloo, Ohio State University, the Australian Nuclear Science and Technology Organization, Kea Pacific Holdings, the Canada Centre for Mineral and Energy Technology (CANMET), the U.S. Geological Survey (USGS) and Environment Canada.

Presenters emphasized that the understanding of sulphide oxidation in tailings impoundments and waste rock dumps is in its infancy but that knowledge is being acquired rapidly.

“These systems are so complex that we’ll never have a complete model,” said Dr. Kirk Nordstrom of the USGS.

Scientists at the University of Waterloo have been focusing their studies on six tailings ponds, specifically those at Heath Steele, Copper Cliff, Waite Amulet, Joutel, Nickel Rim and Kidd Creek. Since sulphide oxidation occurs in a complex, natural system, these investigators are taking various factors into consideration, including chemistry, biology, hydrology and mineralogy. Dr. John Jambor of the University of Waterloo called for more co-operation between hydrogeochemists and mineralogists to carry research forward. Among the most potentially beneficial areas of geoscience, according to Dr. Douglas Gould of CANMET, is the development of inhibitors to prevent the growth of bacteria that catalyze oxidation reactions.

During the alteration course, presenters focused on thermodynamic, experimental, petrologic and lithogeochemical methods used to study alteration systems in ore-forming environments.

Also discussed were alteration studies from various ore deposit environments, such as porphyry copper, skarn, granophile, platinum group elements, lode gold and volcanogenic massive sulphide systems.

David Lentz of the GAC, who organized the courses, said delegates seemed to welcome the combination of theoretical principles and practical examples. A 467-page short course volume, Alteration and alteration processes associated with ore-forming systems, is available from the Geological Association of Canada, Dept. of Earth Sciences, Memorial University, St. John’s, Nfld.

A 440-page volume, Short Course Handbook on Environmental Geochemistry of Sulfide Mine-Wastes, is available for $27 from The Buiness Manager, Mineralogical Association of Canada, Cityview 78087, Nepean, Ont. K2G 5W2. — Patrick Whiteway, the co-author, is editor of “Canadian Mining Journal.”