Abstract:

These web pages form the basis of the "VIGM" elementary school presentation prepared by Alex Doll for the Scientists In the Schools visit to Maple Ridge Elem. The information in this document is based on fictional design options for a fictional gold mine development located on Vancouver Island.

Disclaimer:

The information in this presentation is totally ficticious and is not intended to prepresent any actual gold mine past, current, or future. The design options presented in these documents are based upon the experience of the presenter (Alex Doll) and do not represent the opinions of his employers or others. This presentation is prepared for educational purposes only and people using this information for any purpose do so solely at their own risk.

Summary of Choices:

Mining type:

large open pit

• highest capital cost ($225 million)

• biggest impact on regional environment

• base rate of return of 20%

small open pit

• smallest capital cost ($85 million)

• moderate impact on regional environment

• base rate of return of 12%

small underground (adit access)

• moderate capital cost ($124 million)

• minimal impact on regional environment

• base rate of return of 8%

Processing Type

NaCN leaching

• uses poisonous sodium cyanide solution (NaCN) to dissolve gold

• low environmental risk

• adjust rate of return by 0%

gravity

• uses shaking tables and other machines to separate gold particals (no chemicals)

• no environmental risk

• adjust rate of return by (-10%)

flotation

• uses organic chemicals (similar to pine tree oil) to separate gold particles

• minor environmental risk

• adjust rate of return by (-5%)

Tailings Disposal

effluent treatment & land impoundment

• conventional tailings pond holding benign solution (no chemicals in pond)

• high environmental risk due to impoundment dam breach

• high capital costs ($2.5 million) with moderate operating costs ($1.0 million/year)

land impoundment with decant effluent treatment

• conventional tailings pond holding poisonous solution with treatment prior to discharge

• extremely high environmental risk due to impoundment dam breach

• moderate capital costs ($2.0 million) with low operating costs ($0.5 million/year)

effluent destruction & subsea deposition

• discharging tailings into the base of the river delta via underwater pipeline

• no impoundment to risk breaching. Low risk of polluting the discharging environment.

• Moderate capital costs ($2.0 million) with high operating costs ($2.0 million/year)