The Zimbabwe government has invited tenders for the treatment of calcine dumps, which should lead to the recovery of up to 4 000 kg of gold from the now defunct Kwekwe Roasting Plant, which is owned by the State-owned Minerals Marketing Corporation of Zimbabwe (MMCZ).

President Robert Mugabe’s government is also looking for potential investors who can set up a refractory gold recovery facility for the processing of
refractory gold ores from local mines.

A tender notice published by the State Procure- ment Board late last month reads: “The govern-ment of Zimbabwe is inviting ‘expressions of interest’ in
the treatment of the calcine dumps at the Kwekwe Roasting Plant site and the establishment of a refractory gold recovery facility at the roasting plant site for the processing of refractory gold ores from supplier mines.”

Mines and Mining Development permanent secretary Professor Francis Gudyanga says the prospective investor will be required to treat
calcine dumps, believed to contain up to 625 000 t of milled gold grading an average of 10 g/t.

“Based on work previously done elsewhere, 60% gold recovery from the dumps can be achieved through a process route involving a combination
of ultrafine grinding, with acid pretreatment prior to cyanidation.

On this basis, the dump potentially has at least 3 750 kg of recoverable bullion gold.

“We want to find the technology that can efficiently and effectively extract the refractory gold from the dumps. “The treatment of this ore
requires new technology because we want to migrate from the past roasting method. Government wants to establish a facility to treat the
ore as it comes from other mines that have refractory gold because all is now under the jurisdiction of the Ministry,” Gudyanga says.

According to the Ministry’s estimates, the treat-ment of the dumps and gold recovery processes would cost in excess of $20-million, while the value of the potential gold to be extracted is esti-mated at more than $140-million at prevailing bullion market rates.

The Kwekwe Roasting Plant was established in 1937 to help small and medium-sized gold miners in the processing and marketing of their
product but it closed shop in 2000 owing to a difficult operating environment.