The Implementation of Paste Rock Systems for Preventing Acid Rock Drainage from Waste Rock and Tailings Impoundments

摘要

The present paper demonstrates the application of paste rock for the prevention of acid rockdrainage from waste rock and tailings impoundments. Paste rock is produced by blending pastetailings with waste rock. The new material, known as paste rock, is an engineered material thatoffers superior physical and hydraulic properties for constructing post mining landforms. Testresults show that paste rock materials have a low hydraulic conductivity, high water retentioncapacity (air entry value), high shear strength and low compressibility. These properties can beused to restrict oxygen entry and water seepage in mine waste deposits for minimizing oxidationand metal leaching within sulphide bearing materials. The new material also has densities muchhigher than either conventional tailings or waste rock deposits, thereby reducing the total volumeof waste and surface area requirements for impoundment design and final reclamation. An extensive laboratory testing program along with meso-scale experiments and field scale testtrials using selected blends of waste rock and tailings have been completed. Results show thathydraulic conductivity values for paste rock mixtures equivalent to consolidated paste tailings(i.e. 10~(-7)m/sec to 10~(-8)sec) along with volume change characteristics similar to waste rock canbe achieved. Furthermore, field scale lysimeter measurements demonstrate infiltration rates arereduced by almost 2 orders of magnitude when paste rock is used to construct cover systems.The present paper demonstrates the potential benefits of implementing paste rock at a wellknown site in Canada.