Controlled use of cyanide is one of the options being examined in the local gold-mining industry as countries work on a treaty to control mercury — widely used to recover gold but harmful to the environment when misused.
Chemical engineers here are working on the “cyanidation option” and have completed successful laboratory scale tests, head of the Guyana Geology and Mines Commission (GGMC), William Woolford said last week. “We had the consultant look at the framework for the introduction of cyanidation in a country like ours, the phobia, the technology, the overall requirements…” he added. A team is due here later this month to look at the results of the laboratory tests and will be working with local engineers to scale up to a pilot plant or commercial level. “Cyanidation use will not be for the ordinary pork-knocker and it will only be for selected medium-scale operators… people who have the wherewithal to operate in that fashion,” Woolford stressed.
Officials here have been working on alternatives to mercury in mining after concerns about its effects on the environment. Small miners place mercury in pans of gold-rich ore where the element clings to the gold and sinks to the bottom as the ore is washed off, enabling retrieval of the precious metal. In order to separate the mercury from the gold, miners apply fire resulting in toxic fumes escaping into the atmosphere.
Environmentalists have been critical of the contaminating effects of mercury use on rivers and streams that are an integral source of food among residents of interior communities. The practice of pouring mercury directly into sluice boxes is also believed to have resulted in the contamination of rivers. Research has linked mercury to damage to the nervous system and the brain.
President Bharrat Jagdeo had said last year that mercury use in mining will have to end and the GGMC, in documents, said that mercury use will have to be phased out in two years. A European Union ban on mercury exports takes effect this month while the United States is expected to impose a similar ban in 2013. Globally, countries are working on a mercury treaty.
Questioned on the issue at a press conference last Friday, Woolford said the GGMC had been doing a lot over the years to help miners to improve their recovery system. This included collaborating with miners to set up alternative processing systems that do not require the use of mercury. “In terms of the timeline, we are responding to what the international business community and NGO community are working on,” he said. He said the use of cyanide is looked upon as an alternative and is not necessarily the “top of the line” option since depending on several factors, other types of processing systems such as centrifugal concentrators could garner a higher recovery rate while cyanidation is useful for certain types of ores and deposits.
Woolford also said they have tested different pieces of equipment adding that they are sure that there are jigs and centrifugal concentrators that will be introduced in most of the local gold sector in the near future. Suppliers have gotten on board to supply the alternative equipment, he said.
Meantime, countries under the United Nations are working on a mercury treaty. Manager of the GGMC’s Environmental Division, Karen Livan attended a regional conference in Jamaica in March that was sponsored by the United Nations Environment Programme. The meeting, she said, was to prepare representative of the group of Latin American and Caribbean countries for an inter-governmental negotiating committee to work on a legally binding international instrument for mercury. The committee would have started its work this year with the instrument envisioned to take the form of either a treaty or a convention. The treaty should be completed to be implemented by June 2013, Livan said, adding that “the real implementation may not come until 2015”.
According to Livan, as part of the negotiating process, issues of developing countries like Guyana such as new technologies being developed and finances to develop these technologies are being taken into consideration.
However, she pointed out, the instrument will be much broader than mercury issues in gold mining and will take into its ambit, all aspects of mercury use including in larger industries such as coal mining. But it will have a strong focus on small and medium scale gold mining internationally.
Meantime, Woolford said there has been no case of mercury poisoning at the GGMC. He said there are daily checks in all relevant offices in the organisation using a mercury analyzer. He said that they have not found levels outside the allowable levels but nevertheless, introduced medical checks for lab staff and field staff over the past two years while a new scrubber system has been acquired.
“The GGMC doesn’t have on record any medical report of mercury vapour poisoning of any miner. We’ve had reports that miners and goldsmiths have been exposed to levels of mercury vapour that is above the allowable level but it in a sense it is like if the dumpsite is there and smoke is across the road and you riding through, you may be inhaling things above the allowable level but if you don’t inhale it continuously you’re not really in grave danger,” Woolford added. “I wouldn’t argue that there might not be goldsmiths or traders in gold who are burning gold in an unsafe environment and we are working at saying to them don’t even try it,” he said. He recalled that the GGMC had collaborated, under a CIDA programme, with researchers from abroad and did a comprehensive study, compiled a “dossier on mercury” and from over 1,000 incidents checked, they are “on top of it”.