A focus on Mercury

Scarlett Evans 26 October 2020 (Last Updated October 26th, 2020 09:52)

The use of mercury in mining is known to be so damaging that treaties exist to curb its production and emission. However the material is still used in significant quantities, predominantly in the artisanal and small-scale gold mining (ASGM) sector for processing gold ore. New evidence from mining communities in the Amazon reveals the devastating downstream impacts of this method on both people and ecosystems, and begs the question of how, if at all, this metal can be mined and used safely? We take a look.

A focus on Mercury
Women miners in Ecuador known as “jancheras” search through ore discarded by small-scale mining operations to find pieces with small amounts of gold. Credit: PNGQ, UNDP Ecuador

The mercury problem is a critical one. A paper from Flinders University found that between 410 and 1,400 tonnes of the element are emitted through  artisanal and small-scale gold mining (ASGM)every year, with mercury-based ASGM causing more mercury pollution than any other human activity. While estimates vary, there are 15-20 million people working in the ASGM sector globally, producing up to 20% of the world’s gold between them. The scope of the issue is demonstrably vast, and a recent report highlighting impacts felt by communities in the Amazon is only the latest example of what is a widespread and systemic problem.

Introducing a safer alternative to these small scale workers is an imperative if the issue is to be overcome, yet the method needs also to be economically viable, and come alongside a general overhaul of existing ASGM structures. While no small feat, increasing strides are being seen from organisations and individuals seeking to turn this industry around, and make gold mining safe for everyone.

A toxic problem

The use of mercury in processing gold ore is age old, vastly utilised in the first gold rush throughout the Americas and Australasia. While larger corporations later substituted mercury for cyanide (which breaks down into CO2), small scale miners operating today lack the technology and resources to follow suit. Despite the danger, globally rising gold prices means ASGM has remained steady and the use of mercury has persisted, with excesses of the material often simply dumped into the surrounding environment or leaked into the atmosphere.

Susan Keane, senior director of global strategies for the Natural Resources Defence Council (NRDC), defines it as a somewhat unusual pollutant.

“The chemical nature of mercury means that it can float around the world for a long time before it finally falls out of the atmosphere and deposits,” she says. “So no one country can possibly address this pollution on its own, because mercury from another country could come in and pollute its waters and land.”

The realisation that efforts must be concentrated to tackle this problem came to a head in 2013 with the Minamata Convention – an international agreement in which members pledged to control or eliminate mercury emissions and releases, and eradicate them where possible. It is this convention that Keane says truly brought the issue to global attention.

Given the fact that ASGM provides a source of income for millions of people around the world, efforts to target the problem mainly centre around changes to education and current processing systems, rather than simply eradicating the use of mercury.

“What do you think will happen if you ban mercury right away?” says Keane. “People usually don’t have any other alternatives. All you would do is drive the activity underground and make it harder to help the miners. Of course the aspiration is to eventually get rid of mercury, but if you do it too drastically, before alternatives are in place, you drive everything into the black market and actually undermine efforts to improve the situation.”

Targeting mercury

A true solution would be the development of an economically viable, easily deployable mercury alternative – a tall order given the necessity to make it accessible to millions of people accustomed to the mercury method. Yet it is not impossible.

One such alternative is being developed by Dr Justin Chalker and the rest of his lab from Flinders University, using a sulphur polymer to replace mercury. While the lab was initially engaged in making new types of plastic, with sulphur targeted as a building block, the research quickly turned into mercury remediation, given sulphur’s known bonding capabilities with metals such as gold and mercury.

“We’ve developed a few different methods that don’t use mercury or cyanide to leach gold, and we’ve used some of these sulphur polymers to recover it,” Chalker says. “We have something that meets the criteria of being cheap, fast, and technically simple, and is biodegradable after its been used.”

Yet while the method itself is relatively simple, Chalker says it will take a greater effort in changing the ASGM system before it could be deployed across the sector.

“It’s more than just introducing a new technique that uses benign chemicals,” he says. “For any process to replace mercury, or even cyanide, there has to be an immediate and obvious economic benefit. It also has to be fast, and it has to operate with minimal training, use equipment that’s simple, needs to be portable, needs to use minimal power.”

How solutions are implemented will also depend on the location and geochemistry unique to each area in which ASGM operates, as well as the governance in each region.

“It’s more than a chemistry problem,” Chalker adds, “it’s a development problem.”

A systems change

According to Chalker, miners need to be brought into the formal economy and a broader plan of engagement is required before widespread change can be expected. It is a sentiment echoed by Keane.

“Our emphasis right now is on changing the systems,” she says. “The idea is to help the country develop practical processes so they can become part of the formal economy. It’s a holistic systems approach coupled with education, training, access to cleaner technology and finance, and so forth – but it’s really about helping miners gain access to formal markets to help it become a viable sector.”

The NRDC is part of the Global Mercury Partnership and planetGOLD, initiatives set up to assist in this attempted change of the ASGM sector. Such efforts aim to tackle the problem by supporting formalisation, raising awareness of the issue, and connecting mining communities with mercury-free technologies. While the shift will not happen overnight, it seems attitudes are changing and recognition of the issue is growing – and with it, optimism that a new normal is on the horizon for small scale gold miners.

“We have seen a definite shift in awareness,” says Keane. “It’s a little too early in the game to see big scale changes, but my personal opinion is that awareness is much higher – awareness of the potential for change. These problems take a long time to overcome, but we’re aiming for long term change, not just a one-off intervention.”