Building and characterizing low sulfide instrumented waste rock piles: Pile design and construction, particle size and sulfur characterization, and initial geochemical response

• Main Author: Smith, Lianna
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2009
• Subjects: geochemistry; Acid mine drainage; waste rock; Earth Sciences; Canada; Diavik Diamond Mine; Northwest Territories; Rock Pile
• Online Access: http://hdl.handle.net/10012/4659

A rigorous laboratory and field study to measure and compare low sulfide waste rock and drainage characteristics at various scales has been designed and implemented. The field study was constructed at the Diavik diamond mine in the Northwest Territories, Canada. Three well-instrumented, 15 m high test piles and three sets of 2 m scale experiments were constructed from run of mine waste rock. Diavik waste rock is comprised of granite and metasedimentary biotite schist country rock. The biotite schist contains the sulfide minerals, principally pyrrhotite. Diavik segregates waste rock based on sulfur content. One test pile contains waste rock with 0.035 wt. % S, within the operational sulfur target of < 0.04 wt. % S for lower sulfur waste rock designation. The second pile contains waste rock with 0.053 wt. % S, lower than the operational sulfur target of > 0.08 wt. % S for the higher sulfur waste rock designation. The third pile contains a core of 0.082 wt. % S waste rock which is within the operational sulfur target of > 0.08 wt. % S for the higher sulfur waste rock. The third pile has been re-contoured and capped by a 1.5 m of till and 3 m of lower sulfide waste rock as per the current reclamation plan for the higher sulfide waste rock pile. The test piles were built using standard end-dumping and push-dumping methods. Instrumentation was installed at the base of each pile and on four angle of repose tip faces, as well as in the covers of the third pile. Instrumentation was selected to measure matrix flow, pore water and bulk pile geochemistry, gas-phase oxygen and carbon dioxide concentrations, temperature evolution, microbiological populations, permeability to air, and thermal conductivity, and to resolve mass and flow balances. Instruments were designed to permit measurements at multiple scales. During pile construction samples of the < 50 mm fraction of waste rock were collected. The samples were analysed for sulfur content and particle size distribution. Particle size distributions for the lower ...