In October 2012 Vista Gold implemented an innovative plan to change the pH of more than ten gigalitres of contaminated water stored in the mine site’s open cut pit.
More than six months later, Vista Gold General Manager,Brent Murdoch said that the program has delivered results at the top end of their expectations.
“Without a doubt we have proven that the water treatment program is a viable solution,” he said.
“The results speak for themselves. The pH level of water in Batman Pit has changed from an acidic 3.3 to a neutral 7.9 and 99.8% of all the metals contained in the top 15 metres of water have been taken out.”
Vista Gold’s water treatment program entailed 10,000 tonnes of finely ground limestone and 2,000 tonnes of quicklime added to the water in Batman Pit causing a chemical reaction which increased the pH level and caused the metals to precipitate to the bottom of the pit.
After the water is released the metals will be pumped into the existing Tailings Dam and encapsulated there.
“This process was based on extensive independent scientific research and testing which now sets a benchmark for environmental mine management beyond Mt Todd," Mr Murdoch said.
“While Vista Gold will continue to pursue other water treatment programs, we now have a proven method for managing the volume of water on site until Mt Todd goes into production.”
The Mt Todd mine site still holds a total volume of more than 16 gigalitres of water which will need to be treated and removed from site before the mine goes into production.
Water collection and storage is the biggest environmental issue facing the Mt Todd site. Since the mine ceased operations in 2000 mine affected water has been collected in the Tailing Storage facility (RP7) and the Waste Rock Dump Dam (RP1). This water is then been pumped and stored in the Batman Pit (RP3) as required.
Regardless of the whether the mine goes ahead, this water requires treatment and release from site as historically the Mt Todd mine site receives a net positive of 1.5 gigalitres of water each year.
Vista Gold is also currently looking at evaporation techniques such as land apping for reducing the volume of water.
The release of water from site is governed under licence from the Northern Territory Government and strict environmental controls.
Vista Gold is yet to make a final investment decision on reopening the mine. A positive decision will require a workforce of around 450 people during construction and 350 for the operation of the site.
Vista Gold aims to recruit workers who live in Katherine or Pine Creek, boosting demand for goods and services from local businesses and will continue to show preference for doing business with local companies.
“In addition to local employment and services, long term benefits from Mt Todd reopening include rehabilitation of the site and sound environmental stewardship,” Mr Murdoch said.
Vista Gold General Manager, Brent Murdoch will be available to meet with media on site at 2pm on Thursday, 9 May for a site inspection.
Due to security requirements please register your interest in attending by 5.30pm Wednesday, 8 May.
Protective clothing and a brief site induction will be required.
To register for the site inspection or for further information please contact Jeannette Button on 8941 9169 or 0407 727 080.