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. ~ ~ <br />~~ <br />2) Cyanide Cissolution Time - The Pachuca tar.~s <br />in r•rhich the silver is taken into solution are <br />designed fora 3o hn~rr~ retention tune in order <br />that very dilute (0.1 percent) cyanide solution <br />could be used. This design also yrcatly reduced <br />the residual cyanide remaining in the slurry which <br />significantly simplifies the pollution problems <br />and costs. <br />3) Chlorination - To insure that no free cyanide <br />o-rill be present in the tailings pond,a chlorine <br />system r~ras incorporated into the plant design. <br />Chlorination of effluents containing cyanide is <br />the recommended and standard treatment process <br />used throughout the world. Basically,.the bulldog <br />t•lountain treatment for the dilute cyanide solutions <br />is as follows: <br />a) raise pH to 11 with lime during processing <br />(often all that is needed for cyanide- <br />oxygen reaction) <br />b) injection of 4= chlorine (C12) for each <br />lr cyanide (FlaCfi) in tailings line (oxi- <br />dation of cyanide) <br />c) mix and aerate 23 minutes prior to dumping <br />in pond through tailings line <br />d) deposition of the cyanates o-rith the tailings <br />in the pond. <br />Additional treatment is afforded in the pond by the <br />reaction of sunlight. It is reasonably assured <br />that lrildlife will be in no danger from drin~ing <br />the water contained in the pond. Both the Environ- <br />mental Protection Agency and State Dapartm°nt of <br />Health have bezn advised of thz proposed car;;u;i-in- <br />puip plant and are familiar arith the process. EffLlen* <br />limitations from the ber,zficiation operation is <br />covered by MPOES 0ischar~r' Permit fdo. CD-0000711!. <br />Close monitoring of 'ht' pond will be coni!ucted <br />during plant operations. <br />D. Visual Pollution - The propose' project ti•,ill lave little <br />visual impact because of the er.isting structures. Tyro b~.:ild- <br />ings, one storage tanl, and a pp.=_line ~•rill be vl~ysically <br />separated frOril the pre^.znt r^111 structure. ;r. overhear! oo:•rer <br />llne l~llll dli~l be needed t0 supC~l`; PO:+er t0t^e pon,l arz,. <br />~• <br />-- - . . . ... .. .. .. . .--------1 ] 6 - - <br />