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• 999 <br />BATTLE MOUNTAIN GOLD COMPANY <br />ANDRE J. DOUCHANE <br />GENERAL M.INAGE0. <br />NORTH AMERICAN OPERAHONS <br />April 1, 1992 <br />Mr. James C. Stevens <br />Geohydrologist <br />Colorado Mined Land Reclamation <br />Division <br />1313 Sherman St. <br />Denver, CO 80203-2273 <br />Re: Permit M88-112 Technical Revision <br />Dear Mr. Stevens: <br />• .~.~- <br />~~GO EC MgWYN <br />~~C~ih~tf:.~ <br />a~~ 3 ~99? <br />Mined ~a d <br />Reclamation n~,,:..;,,~ <br />Thank you for your time to meet with Matt Lewis t <br />the tailings detoxification system (AVR) at the San LI <br />As you are aware, cyanide concentrations in the tail: <br />are greater than originally anticipated at the time tl <br />application was approved. In general, BMR beleives tl <br />concentrations are attributed to differences <br />characteristics. Additionally, there are some indicat <br />natural cyanide degradation in the tailings pond may <br />significant as previously predicted during winter col <br />The original ore test program is still valid for the <br />the ore, with the exception of a potential increase <br />contained in the ore. To immediately respond <br />situation, BMR has requested approval to utilize zinc <br />sulfate as a detoxification reagent. The sulfate will <br />to the slurry line prior to the A\7R system in either a <br />or dry state form. The initial application stren <br />provide excess free cyanide detoxification capacity f <br />the pond. The sulfate concentration will then be re <br />the level necessary to detoxify the fresh tailings slu <br />placed in the tailing facility. We expect the comple~ <br />to be detoxified of free cyanide in approximately 14 d <br />collection pond below the main embankment will be di <br />immediately upon CMLRD approval by directly adding the <br />to the lined conveyance ditch which carries flow from <br />blanket to the collection pond. <br />discuss <br />is mine. <br />3gs pond <br />permit <br />;higher <br />in ore <br />Dns that <br />lot be as <br />ditions. <br />bulk of <br />n copper <br />to this <br />ferrous <br />be added <br />solution ~ L <br />lth will tA.t.,~.+ d6o.'-~ <br />Ir use in G N ~}.. <br />duced to t~,~~~r <br />-ry to be <br />e system <br />iys. The <br />toxified <br />sulfate <br />:he drain <br />The sulfate addition will reduce the concentra 3_ons of <br />free cyanide in the pond. A substantial reductio in WAD wG"'~P'~`~~~ <br />cyanide levels will require potentially longer term t eatment, <br />which BMR is currently evaluating. BMR believes that the <br />5670 GREENWOOD PLAZA BLVD. SUITE 106 ENGLEWOOD, CO 80111 (303) 721 b741 FA%(303) 721 813 <br />