Post on another board (Revello)
Someone at Excelsior Mining informed me that the company is constantly looking for a quicker, more efficient way to address the CO2 issue.
Optimal solution would be a method that removes the CO2 as it builds up, but still allow injection of SO2 and extraction of copper sulfate at the same time.
I'm not an engineer, but I've worked with engineers who work on environmental remediation systems to address volatile organic compounds (VOCs) in soil overlying groundwater, and VOCs in groundwater. One would think that if you did a soil vapor extraction in the zone above the groundwater, and air sparged in the groundwater zone to force gaseous carbon dioxide to rise into the non-wet soil zone and be captured by the soil vapor extraction, that might alleviate the resisting pressure from the gaseous CO2 that they're encountering.
The water flushing process they're currently using mixes the water and CO2 to form carbonic acid, which is relatively harmless compared to other acids. Not sure how/what they do to treat/handle the carbonic acid mix, but I guess there's an easy process to separate the CO2 from the carbonic acid to reform H2O and then reinject in cyclic loop.
Again, I'm not an engineer, so take what I said above with a grain of salt (and swig of carbonic acid). Maybe the company should discuss the problem with an engineering firm such as Jacobs Engineering (who acquired CH2M Hill). They have loads of experience and talent dealing with groundwater remediation, pumping, soil vapor extraction, etc.