Laserfiche WebLink
III IIIIIIiit1111Iii <br />~ STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Department of Natural Resources <br />1313 Sherman 51., Room 215 <br />Denver, CO 80203 <br />303 866 3567 <br />FA X. 303 632-6106 <br />OF ~~[O <br />v''ie ~' + <br />.~ ~~~~ <br />~ ra76 ~ <br />Roy Romer, <br />Governor <br />Michael B. Long. <br />Division Director <br />DATE: April 5, 1992 <br />T0: Larry D. Oehler <br />FROM: Jim Pendleton <br /> <br />RE: "Technic .YReport Proposal - Cyanide Detoxification <br />Response to 3/31/92 NOPV <br />Preliminary Technical Revision Application <br />Battle Mountain Gold (Permit No: M-68-112) <br />at San Luis" <br />(~ev~ <br />I have reviewed the chemical engineering study referenced above. Briefly, the <br />report discusses five possible remedial actions to be used to reduce the <br />cyanide content within the tailings slurry at the Battle Mountain Gold (BMG) <br />mine near San Luis. The report was prepared for BMG by BEI Engineers / <br />Constructors Inc. (BEI), consultant to BMG. The conclusion of the report is <br />that the preferred method for detoxification of the tailings is through the <br />use of "Cytox" chemicals, which are a proprietary product marketed by BEI. <br />The report presents data which projects relatively rapid reduction of the <br />cyanide within the slurry through the application of the "Cytox" chemicals. <br />"'Cytox' (derived from ~anide detoxification) is a ferrous sulphate compound <br />'stuffed' with differing levels of zinc." BEI represents "Cytox" to be an <br />improvement over the relatively common Ferrous Sulphate process. The drawback <br />of the Ferrous Sulphate process being that the end product is "highly soluble" <br />in comparison to the "totally stable" end product of the "Cytox" process. <br />Discounting BEI's Choice of descriptive language within its proposal / report, <br />the data suggests that the "Cytox" chemicals do result in a more stable end <br />product precipitate than the more common Ferrous Sulphate process. However, <br />BEI does Include cautions within its report. The data presented wa3 collected <br />under laboratory conditions. BEI also observes that the source of $MG's <br />problem is probably an excess of Copper, resulting from the unexpected Copper <br />content of the San Luis ore. BEI projects that methodology could b@ developed <br />to remove the excess Copper levels from the tailings slurry. Finally. BEI <br />projects that a long term slurry treatment could be implemented to Maintain <br />low cyanide and Copper levels in the tailings slurry. <br />In the interest of eliminating the potential hazard represented by the <br />existing elevated cyanide levels in the BMG tailings, I recommend that we <br />approve the use of the proposed "Cytox" process. We should, however, place <br />number of conditions upon approval of their technical revision, as follows. <br />(1) The purpose of this remedial activity is to bring the existing tailings <br />into compliance with the originally approved permit requirements. <br />