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<br />• F.~"~~ <br />d- Total WAD (true WAD plus Free cyanide) shall not exceed 40 ppm under the <br />following formula: <br />True WAD + 1.3 Free CN = 40 ppm ato'N s.qz ~ <br />5. The Modified 7ailinss <br />The writer refers to the penultimate paragraph, page 2 of Doc. Na. 2382F. ~ <br />,' <br />BEI presumes that Dr. Pendleton's astute observations refer to: <br />a. Potential acidity increase in the tailings ("modified tailings"). <br />b. Potential increase of metal-cyanide (WAD) complexes in the tailings. <br />These concerns are real and have been addressed by BMG, BEI, and Dr. Adrian Smith <br />and are here below reviewed; <br />A. Acidit <br />By introducing art acidic (and acid-generating) Compound, Cytox, one was <br />concerned about the potential of generating reaction-products that could <br />turn the tailings acidic, before, during, or after, reclamation. <br />Two reviews have been conducted so as to assure BMG and BEI that this <br />shall not occur <br />Review 1 Today, BMG is permitted t0 use an AVR system that uses 2 1bs <br />of HZSO4 per ton of milled ore. This condition has been <br />approved by the state as "safe" ih terms of acidity. The <br />i ~6=~ ; ,-~=, r C~_ F~ZS~4 introduction of Cytox shall be in-place of H2$04 in the AVR. <br />Barringer Labs of Go1~~n, Ca lorado, have confirmed the acidity <br />S ~~ ~ /1 20~~00 7 ~, e ofi Cyto~C as 235 tans~p2r 1000 tons of Cytox compared to 20, 000 <br />tons~per 7000 tons of Mi501. A change in chemicals, <br />5~„~ ,./ ,~c~ therefore, should reduce the potential acid load of the l~~oEtV~~~~ <br />r/ lJ°~ J;. { : system. <br />rl ZrcU '.wt.f.^Atc F <br />~y,~~ Grc~..-t Review 2 "Care laboratories" has d®termined that the use of "Cytox" <br />1 ,;~ ~, shall provide the San Luis operation with 9.2 tons of acid-I <br />•~'^~` neutraTizing potential per 1000 tons of tailings and thus, <br />ti9s~ ,Yh~ K r~`~o , N,~oy CyTOx should not change the acid generating potential at San <br />Luis. - ~ ~J <br />~a,e=o ~ e*r 7.:,er:~ r '~.e ,~ ,,Q yr¢a~rw~r . <br />B. Potential Increased WAD W'~'~'~ <br />99% of the WAD complexes at San Luis are Cu WAD Capper WAD's are <br />especially problematic since it is hard to destroy them in normal mine <br />operations because ait solutions have a high pH, and yet they can break <br />down relatively easily after reclamation. <br />metals analysis of the tailings at San Luis suggests that the only WAO <br />~ , is that of copper. Without treatment it would reside in the tailings at ~ ~ o <br />~,~ ;p. closure and thus cause concern. BMG and EI are curranr.ly t1Pt.Pinpinn a <br />~~C~'' process to remove Cu WAD which is expected to be available within 30 davs., ~T~,l_,a,, <br />y - / " <br />.~~ <br />y.i ~. 4~ , <br />~~~ ~ <br />S ~~' <br />