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Finch Report <br />BENCH-SCALE STUDY FOR TREATABILITY TEST <br />June 25, 2008 <br />by Linda Figueroa, Ph.D. and Andrea Koenig, Ph.D <br />Environmental Science and Engineering, <br />Colorado School of Mines <br />Introduction <br />This report outlines the results of a bench-scale study for a treatability test. CSM <br />examined an enhanced passive neutralization technology (EPN) in parallel with a <br />conventional limestone system to perform the treatability test on synthetic Tiger Tunnel <br />mine drainage. The purpose of the treatability test was to evaluate the efficacy of the <br />EPN technology for the treatment of three key constituents in the mine drainage: nuneral <br />acidity, iron and aluminum. The EPN technology involves the use of limestone and <br />pebble lime in varying ratios to reduce the required hydraulic residence time in the EPN <br />drain relative to limestone alone. Pebble lime is a very effective neutralizing agent but <br />alone will increase the pH above the desired effluent value of 6 to 8. The proper <br />combination of limestone and pebble lime was expected to provide effective <br />neutralization, moderate the pH increase and reduce aluminum and iron from the Tiger <br />Tunnel mining influence water (MIW) <br />Bench-Scale Testing Objectives <br />111 support of this treatability test, CSM performed laboratory tests with <br />synthetic Tiger Tunnel mine drainage. The synthetic MIW was prepared based upon the <br />major compounds and pH of the water from a 2007 analysis of the Tiger Tunnel none <br />drainage provided by Karl Ford of the BLM. The synthetic water was treated with either <br />limestone (CaC03) or a combination of limestone (CaC03) and pebble lime (Ca0) in <br />order to increase the pH to a neutral level and to precipitate aluminum and iron from this <br />acidic MIW. The goal is to create a system that is simple, passive, inexpensive and that <br />can be scaled-up for the Tiger Tunnel mine drainage site. <br />The lab tests consisted of both batch and advective-flow experiments. The objectives of <br />the laboratory tests were as follows: <br />Batch-experiment objectives <br />• Determine the amount of limestone and pebble lime required to neutralize the water and <br />precipitate aluminum and iron. <br />• Determine the effect of time on the rate of neutralization. <br />Advective-flow experiment objectives <br />• Evaluate the effect of hydraulic residence time on effluent pH, iron and aluminum. <br />The bench-scale treatability effort is intended to provide information to determine the <br />Frg~ter~oa EP~-re1x~rt, Jztne ?~, 200< <br />