GREY:VITFF - Post by User
Comment by
HoneyBadger77on Jul 17, 2024 1:48pm
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Post# 36136978
RE:RE:RE:A clue perhaps?
RE:RE:RE:A clue perhaps?Great info MDJ! Thanks for the digging!
The snow accumulation and melt considerations could certainly relate to VG's current situation. HLP experts consider excess water on a HLP as the leading cause of ore slides and that could be a main contributing cause in this case. I didn't read it all but don't believe there is anything in the report about steep embankment or ore itself actually leaving the pad as has occurred at Eagle. Of course if the Brewery Creek HLP has a much less steep / gradual slope and plenty of embankment around it then that consideration would not have been needed.
Section 4 has lots of great info and the in-situ bacteria detox process decribed in 3.7.3 is an interesting detox method that sounds quite effective.
3.7.3 Heap Leach Pad Detoxification and Effluent Management
After mine closure, the heap leach must go through a detoxification process to remove the potential of toxic elements from entering the environment. During the regulatory process, the initial plans proposed included a fresh water rinsing process. Detoxification was expected to be completed in six months. The method ultimately adopted by Viceroy was a process call in-situ bacteria detoxification.
The in-situ bacteria process involves mixing nutrients such as sugars, alcohol, and fats with water that is then spread over the heap. The existing bacteria present in the heap use the nutrients to transform the cyanide and other metals into an inert state. The process was initiated in 2002 and continued until 2003, after which the heap leach was considered clean.
Heap effluent (water used in detoxifying the heap) was stored in the process ponds and overflow pond and was monitored regularly for water quality. Most suspended solids in the heap effluent settled out. By July 2003, the water quality had improved considerably with the exception of selenium. The heap effluent was released into the receiving environment through a combination of water sprinkling and groundwater releases between 2002 and 2005. The releases were in accordance with Canadian Council of Ministers of the Environment (CCME) approved guidelines, and water licence restrictions. Information of the heap effluent releases can be found in annual water licence reports reported by Viceroy and Alexco.
HB77