Online Reporter
Fungai Lupande-Mashonaland Central Bureau
THE Government has intensified efforts to eliminate the use of mercury in artisanal and small-scale gold mining, with officials conducting baseline data collection and technical feasibility assessments for safer gold processing technologies in Mashonaland Central Province.
Officials from the Department of Metallurgy under the Ministry of Mines and Mining Development, the Environmental Management Agency, and the Planet Gold Zimbabwe project this week visited Kuzivakwashe Mining Syndicate in Mazowe District and Chiweshe Rosa Mine to assess the viability of establishing mercury-free gold processing centres.
Department of Metallurgy official Mr Reginald Chidawanika said the assessments are part of the development and rollout of alternative gold processing technologies aimed at protecting miners and the environment from mercury pollution.
“We are carrying out baseline data collection on the development of mercury-free technologies,” said Mr Chidawanika.
He said three methods are currently under assessment.
“The primary one is the leaching and precipitation method where we use ordinary bleach and hydrochloric acid. When they are mixed together, they release chlorine gas, which dissolves the gold,” he explained.
“When the gold gets into solution, we can separate the gold-bearing solution from the siliceous gang material through filtration. After recovering the solution, the gold can then be re-precipitated using sodium metabisulfite.”
Mr Chidawanika said the second method targets ores containing coarse-grained free-milling gold.
“After milling the ores and recovering concentrates using conventional gravity concentration equipment, miners can further grind the concentrates before cleaning the gold using Falcon concentrators, Nelson concentrators or Gemini tables,” he said.
“After recovering the gold, it can be taken straight for smelting.”
He said miners whose ores do not contain significant quantities of free gold could process them through cyanidation or other leaching methods without using mercury.
Mr Chidawanika said the technologies being developed are affordable for small-scale miners because they use readily available reagents and simple processing equipment.
Some ore samples, he said, have already been sent to South Africa for metallurgical test work to obtain expert recommendations from accredited laboratories.
“I would like to think that by year-end we would have established some of these methods at some of our small-scale mines because we are now at the stage of developing mercury-free technologies,” he said.
Planet Gold Zimbabwe project manager Mrs Nyaradzo Mutonhori said the initiative seeks to reduce mercury use in artisanal and small-scale gold mining over a five-year period.
“The aim of Planet Gold Zimbabwe is to reduce the use of mercury in traditional small-scale gold mining by 4,85 tonnes at the end of five years,” she said.
Mrs Mutonhori said the project is being implemented in 11 districts across Zimbabwe, with plans underway to establish eight mercury-free gold processing centres.
