ENFORCE25133

• Permit No: M1988112
• IBM Index Class Name: Enforcement
• Doc Date: 4/5/1992
• Doc Name: TECHNICAL REPORT AND PROPOSAL CYANIDE DETOXIFICATION AT SAN LUIS RESPONSE TO 03-31-92 NOPV PRELIMINA
• From: MLRD
• To: LARRY D OEHLER
• Media Type: D
• Archive: No

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MINED LAND RECLAMATION DIVISION
Department of Natural Resources
1313 Sherman St., Room 215
Denver, CO 80203
303 866-3567
Fnx'303 832-8706
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Ray Romer.
Governor
Michael B. Long,
Division Direnar
DATE: April 5, 1992
STAT~OF
T0: Larry D. Oehler ~
FROM: Jim Pendleton -,i,l~~~--~
RE: "Technics ep~ Proposal - Cyanide Detoxification at 'San Luis"
Response to 3/31/92 NOPV
Preliminary Technical Revision Application
Battle Mountain Gold (Permit No: M-88-112)
I have'reviewed the chemical engineering study referenced above. Briefly, the
report discusses five possible remedial actions to be used to reduce) the
cyanide content within the tailings slurry at the Battle Mountain G ld (BMG)
mine near San Luis. The report was prepared for BMG by BEI Engineers /
Constructors Inc. (BEI), consultant to BMG. The conclusion of the r port is
that the preferred method for detoxification of the tailings is thro gh the
use of "Cytox" chemicals, which are a proprietary product marketed b BEI.
The report presents data which projects relatively rapid reduction o the
cyanide within the slurry through the application of the "Cytox" the icals.
"'Cytox' (derived from ~anide detoxification) is a ferrous sulphate compound
'stuffed' with differing levels of zinc." BEI represents "Cytox" to be an
improvement over the relatively common Ferrous Sulphate process. Th drawback
of the Ferrous Sulphate process being that the end product is "high) soluble"
in comparison to the "totally stable" end product of the "Cytox" pro ess.
Discounting BEI's choice of descriptive language within its proposal / report,
the data suggests that the "Cytox" chemicals do result in a more stale end
product precipitate than the more common Ferrous Sulphate process. owever,
BEI does include cautions within its report. The data presented was collected
under laboratory conditions. BEI also observes that the source of B G's
problem is probably an excess of Copper, resulting from the unexpect d Copper
content of the San Luis ore. BEI projects that methodology could beydeveloped
to remove the excess Copper levels from the tailings slurry. Fina11~, BEI
projects that a long term slurry treatment could be implemented to m intain
low cyanide and Copper levels in the tailings slurry.
In the interest of eliminating the potential hazard represented by tt}e
existing elevated cyanide levels in the BMG tailings, I recommend that we
approve the use of the proposed "Cytox" process. We should, however,lplace
number of conditions upon approval of their technical revision, as fdllows.
(1) The purpose of this remedial activity is to bring the existing tlailings
into compliance with the originally approved perm?t requirements.