Victoria, Australia-based Minerals and Metals Group (MMG) announced in early November a restart of its commitment to develop three major projects, including $60.4 million to expand production capacity at the Sepon copper operations in Laos; $3.7 million for design and construction of a flotation desliming circuit at Sepon to improve pyrite recovery; as well as $24 million to design and construct a new tailings storage facility at Golden Grove in Western Australia. The previously announced expansion program was suspended in September 2008 due to economic uncertainty.
The Sepon copper and gold operation comprises a 1,250-km2 contract area located approximately 40 km north of the town of Sepon in the Savannakhet Province of south-central Laos. Gold production at Sepon commenced in December 2002 and copper in early 2005.
According to the company, the copper expansion project will increase annual copper cathode production at Sepon from around 65,000 mt to a nameplate capacity of 80,500 mt.
The flotation desliming circuit at Sepon will allow improved pyrite recovery from the leach tails to maintain soluble iron levels in the copper processing circuit. This will result in a reduction in the amount of pyrite purchased annually to supplement the flotation concentrate production and the potential for acid formation in the tailings storage facility.
The new tailings storage facility at Golden Grove will ensure continuity of mining operations with up to 15 years of tailings storage capacity. MMG expects the new tailings storage facility to be commissioned by mid-2010 with design and regulatory approval complete and early works already commenced.
The company noted that significant improvements in copper production capacity at the Sepon operation have already been achieved with the commissioning of the second autoclave this year which saw capacity increase from around 64,075 mt/y last year to a forecast of 67,500 mt this year.
The expansion project, which was scheduled to begin immediately and is expected to be completed in December 2010, will increase plant throughput from 1.35 million mt to 2 million mt/y. The project will include modifications to the current plant including increasing the size of the run of mine (ROM) crusher, an additional surge tank, cooling tower, spiral heat exchangers, thickeners and electrowinning cells.
