The Government has stepped up efforts to end the use of mercury in artisanal and small-scale gold mining.
Officials are collecting baseline data and carrying out technical assessments of safer gold processing technologies in Mashonaland Central Province.
This week, officials from the Department of Metallurgy under the Ministry of Mines and Mining Development, the Environmental Management Agency, and the Planet Gold Zimbabwe project visited two sites in the province.
They went to Kuzivakwashe Mining Syndicate in Mazowe District and to Chiweshe Rosa Mine. The visits were to check whether mercury-free gold processing centres could be set up there.
Reginald Chidawanika, an official from the Department of Metallurgy, said the assessments are part of a plan to develop and roll out alternative gold processing methods.
The aim is to protect miners and the environment from mercury pollution. He said three methods are currently being assessed.
“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,” Chidawanika said.
“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 reprecipitated using sodium metabisulfite.”
Chidawanika said the second method is for ores that contain coarse-grained gold that is easy to separate.
“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 ore does not have much free gold could use cyanidation or other leaching methods instead. These methods do not need mercury.
Chidawanika said the new technologies are affordable for small-scale miners. They use reagents that are easy to find and simple processing equipment.
He added that some ore samples have already been sent to South Africa. Accredited labs there will carry out metallurgical tests and give expert advice.
“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,” said Chidawanika.
The initiative will reduce mercury use in small-scale gold mining by 4.85 tonnes over five years, said Planet Gold Zimbabwe project manager Nyaradzo Mutonhori.
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