CHAPTER 15 STATE OF THE ART TECHNOLOGY FOR ENVIRONMENTAL PROTECTION IN THE MINING INDUSTRY

• Jurisdiction: Derecho Internacional

Mineral Development in Latin America
(Nov 1997)
CHAPTER 15
STATE OF THE ART TECHNOLOGY FOR ENVIRONMENTAL PROTECTION IN THE MINING INDUSTRY
Dirk Van Zyl
Golder Associates Inc.
Denver, Colorado

1. TWO BIG ENVIRONMENTAL ISSUES FACING THE MINING INDUSTRY

• Water quality

• Land use

2. DESIGNING FOR CLOSURE

• Issues

• Physical stability

• Chemical stability

• Land use

• Options

• Walk away

• Passive care

• Active care

3. CHEMICAL STABILITY

• Source control

• Migration control

• Treatment

4. TECHNOLOGIES AND CASE HISTORIES

4.1 Mine waste characterization, segregation and cover

• Use best technology to characterize waste, credible geochemist

• Potentially acid generating and non-acid generating materials

• Segregate during operations to limit water contact with acid generating materials

• Surface water diversions and cover (interim and permanent) cover placement to limit infiltration

• Chemical stability, source and migration control

4.2 Coal mine pit closure, Ravensworth Australia

• Reclamation of final cut of open cut coal mine using dense slurry ash disposal

• After placement use a cap of at least 1m of spoil

• Physical stability

4.3 Wetlands for reclamation of kaolin mine, Macon, Georgia

• Wetland constructed to mitigate impact, mimic bottomland swamps in function and appearance

• Backfilled pit with stockpiled overburden and cover of 150 mm loamy overburden was placed

• Soil was limed and fertilized and covered with 150 mm of topsoil stripped from a wetland.

• Vegetation re-established rapidly

• Physical stability

4.4 Mine closure at Blackbird, Idaho

• Intermittent mining of copper and cobalt since 1890

• Problems:

• ARD from waste dumps

• Underground mine discharge

• High dissolved copper runoff

• Downstream salmon fishery restoration

• Remedies:

• Water treatment and maintenance in perpetuity

• Collection of contaminated water

• Diversion of clean water around facilities

• Physical and chemical stability (treatment) and land use

4.5 Flooding of tailings Stenjokk, Sweden

• Sulfide ores mined for copper, zinc and silver from 1976 to 1988

• Coarse tailings backfilled, fines deposited on surface

• Alternatives for closure: flooding, dry till cover, pyrite cleaning and buffering

• Flooding selected, completed in summer of 1991

• Char in ponds by 1997

• Chemical stability, source control

4.6 Quirke uranium tailings closure, Ontario, Canada

• Mining started in 1955...