In its June quarter outlook, the Bureau of Agricultural and Resource Economics and Sciences also expected notable gold production rises out of Papua New Guinea, China and African nations outside of South Africa this year.
Feasibility studies for an expansion of Hidden Valley were about halfway complete in November, and gold production from the mine amounted to 1.59t on a 100% ownership basis in the March quarter - a rate of 6.35t per annum for that period.
A 26% ramp up from that figure to 8tpa of gold would equate to 282,191 ounces each year.
The mine held 5.6 million ounces in the ground, according to a Newcrest presentation at a global mining conference last month, indicating that Hidden Valley could support another 20 years of mining.
Harmony said in its March quarter report the mine became connected to the grid of PNG Power.
This allowed the mine to receive up to 10 megawatts of electricity, or more than 60% of requirements, and reduced the need for onsite diesel-fuelled power generation.
ABARES forecast global gold production to grow 2% to 2780t in 2012.
South African gold output is forecast to fall a further 5% to 183t next year, while China is expected to remain the biggest gold producing nation.