The Use of Mercury in Artisanal & Small Scale Gold Mining

Christian is a Project Manager at Minespider.
Christian Ecker
A comprehensive overview of mercury and its uses in artisanal and small scale mining. It covers the Minamata Convention on Mercury, the uses in Artisanal and Small Scale Gold Mining (ASGM), and the alternatives, as discussed with Cyrus Njonde Maina of Impact Facility.
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Mercury is the only metal that is fluid at room temperature. It used to be used in thermometers or light switches, but has been phased out of most applications in recent years.

The reason? It is very poisonous.

The neurotoxin can impair your vision, harm organs, lead to neurological damages, cognitive and motoric malfunctions, and ultimately be fatal.

So why are we talking about this in our ASM series? In fact, Artisanal and Small Scale Gold Mining (ASGM) is a key actor in global mercury consumption, using it to separate gold from other sediments.

In the mix, mercury binds the gold in an amalgam, which is then heated up so that the mercury evaporates and the miners are left with a gold nugget. Many artisanal miners operate without protective gear and are unaware of the extent of the risk, stirring the mercury mix with their bare hands and emptying the containers on site.

The burning often happens either with an open flame, or in ovens, and in many cases without devices to contain the vapor. This is not only damaging for miners but entire communities, as the spilled or vaporized mercury disperses, and spilled mercury travels up the food chain through water or aquatic creatures that are consumed by humans.

The Minamata Convention on Mercury

Recognizing the danger, an international treaty on its use and trade was adopted in 2013: The Minamata Convention on Mercury, which to-date counts 128 signatories.

It stipulates an end to mercury production within fifteen years, and prohibits mercury import and export, manufacturing, and a number of mercury-containing products by 2020 — except for countries who request a five-year extension. Moreover, it also lays out policies to prevent damages to humans and the environment. All these stipulations are to be implemented through National Action Plans on the country level, by the respective governments.

This, however, has proven to be insufficient to eliminate mercury use, since the trade has found new channels.

The EU and the USA banned mercury export in 2011 and 2013 respectively, allowing its export only for scientific research. However, this has led to a situation where prices in areas which haven’t phased out yet are increasing, leading to smuggling and fraud.

In Germany, for instance, in 2016 the head of a recycling company was sentenced to prison for illegal mercury trade. He had mislabelled pure mercury as “mercury containing hazardous waste”, and exported it to Switzerland, from where it was sold abroad.

Several hundred tons of illegal mercury entered the market through this scheme.

Other countries exploit the long periods granted for the gradual phasing out of trade and production, shifting the principal trade to East Asia and Latin America. Countries such as Mexico reopened mercury mines that they had already shut down to fulfill the demand that other countries who had already abandoned mercury production cannot fulfill.

The IUCN National Committee of the Netherlands (IUCN NL) has published a report on the new trade hubs: in Latin America these are Bolivia, Guyana, and Surinam. In Africa, hot spots include Tanzania, Kenya, and Burkina Faso. In East Asia, the Philippines stick out. The trade of mercury remains global.

Sizeable Reporting Discrepancies

The clandestine nature of the trade, even before the adoption of the Minamata Convention, becomes evident in another report by the WWF, Gaia Amazonas Foundation and the UN, which cites high discrepancies in the amounts of mercury reported as exports from one country, and imports by another between 2011 and 2015.

Consequently, mercury suddenly “goes missing” and is not accounted for. In the mentioned time frame, the UK reported to have imported 200 metric tonnes less than what exporting countries claim to have delivered. Other countries had concerningly high gaps as well, for example Germany and Poland (50 tons), and Indonesia (40 tons).

The trade, it seems, has become as elusive as the metal itself.

The use of Mercury in Artisanal and Small Scale Gold Mining.

Circle back to ASGM: mercury is highly important for this sector but often poorly handled, putting communities and the environment at risk.

The Minamata Convention, one should hope, would reduce the consumption, however this is not evident. The latest UN Global Mercury Assessment 2018 estimates that in 2015, ASGM operations released 1225 tons of mercury into the environment, about 38% of the annual total.

More recent figures estimate the annual release caused by ASGM to be around 2000 tonnes— which means the consumption has actually increased in the years since the Minamata Convention passed. ASGM continues to be well-supplied with the liquid metal.

There are many reasons for the high demand in the sector. Apart from a lack of awareness of the toxic side effects, mercury is used because it’s easy to transport and apply, and yields quick results. In the short run, it is also cheaper than investing in other technologies, especially considering that many artisanal miners are working informally and do not have access to the capital needed in order to transition to cleaner technology.

What is more, often, the buyers of the gold provide the mercury, creating a lock-in effect and a relationship that is hard to change.

So, at the end of the day, the Minamata convention and national policies are undoubtedly good and necessary steps. However, they are not sufficient, and have to be complemented by directly supporting the miners.

Credit: Cyrus Njonde Maina; panning gold concentrates with gloves to avoid mercury Contact, Tanzania Mine

What are the alternatives?

Luckily, there are alternative approaches. Retorts, for example, capture mercury vapor when the amalgam is burnt. Essentially they are a container with a long neck, tilted downward. The vapor is caught in the neck and then condenses. It can later be reused, reducing emissions by 90–95%.

Alternatives that work without mercury altogether exploit the concept of gravity and the weight difference between gold and sediment particles. For that method, the ore needs to be crushed or milled. It is then put in a centrifuge, where heavier materials, such as gold, are collected and lighter materials washed out. Next, on vibrating shaking tables, gold and sediment particles rattle in one direction, a process during which the heavier gold and lighter sediment are separated. Then the gold particles, which are heavier, can be recovered and taken for final smelting.

Another chemical process is leaching, where gold is mixed with cyanide and dissolved. After this process, gold is extracted when carbon particles bind the gold solution or other reagents. The gold-carbon mix is then smelted, yielding the final product with a recovery rate of about 90%. This process requires a considerable amount of technical know-how as well, since cyanide is poisonous itself — albeit much less so than mercury.

How to start the transition.

We were fortunate enough to speak with an industry expert, Cyrus Njonde Maina to understand the alternatives. Cyrus is a mining engineer and Regional Manager for East Africa with the Impact Facility, an NGO working to empower ASM communities economically, socially and environmentally. Their approach is three-fold, providing miners with access to finance and equipment, capacity building, and ethical markets. Among those, they also provide equipment that reduces or eliminates the use of mercury.

The Impact Facility, he explained, works with local partner organizations, such as mining associations, who are known to the ASM communities and have a history of working together. Through them, as an already trusted entity, they can communicate with the communities.

As Cyrus explained, the approach is always to go to the communities, speak with them and understand where they are coming from and what they need.

Using their due diligence tools, Impact Facility aligns with what they are looking for.

“We talk with them, we don’t bombard them with technology.”

Together with the ASM communities and partner organizations, next steps are decided on.

It is important for everyone to see the benefits of the proposed solution, which is why prototypes are key for demonstration purposes.

A crucial point: Mercury-free production is not only safer, but also more efficient.

As Cyrus explained, the Impact Facility collects and analyzes data on mercury consumption and gold output, provided by the miners. When presenting the results to the miners, the numbers speak for themselves.

“So we are not trying to push, it’s for them to make a decision at the end of the day. The new technologies are not a way to fight mercury, but to help the miners to understand that there are always better ways to do processing.”

— Processing, in fact, that results in close to 100% of gold recovery.

Apart from the production-related improvements around health, safety, and processing, the legal status of the mining is part of the work plan, too. At the outset of the process, the Impact Facility makes sure the miners are formalized and have the necessary permits — where this is not the case they support the process, not financially but with guidance:

“Most artisanal miners, they fear the government. But now they’re actually getting better. They are able now to go to government offices and ask ‘What do I need?’. And that is one thing that we are trying to do, to bridge the gap between the government and the artisanal miners”.

Regarding transition to mercury-free production, a project in Uganda provides useful insights: At the end of two year process of training in business, governance, safety, child labor, and technology, among others, stood the formalization of all four mines involved, improved health and safety standards, and a mercury-free gold processing plant, using a shaking table.

In that case, Ugandan miners, aware of the danger of mercury exposure, were actively looking for alternative approaches. They know they have the gold, what was missing was better means to get it out of the ground.

Flexible financing.

How is the plant in the example going to be financed? By a pay-per-use scheme.

This way, no single person or organization has to assume the burden of the investment needed to install it, and the entire community benefits. The prefinance of 10% is the only upfront investment needed, and miners are well sensitized as to the financial planning of the project. To this point the financing model has not been implemented, since the rainy season in Uganda took longer than usual. This leads to lower yields, as miners are busy getting the water out of their pits.

Furthermore, Covid-19 has hindered movement for the miners and field visits. As a result, the processing plant has so far been under-utilized. There is, however, optimism that the finance model will work in the near future.

Cyrus described the miners in Uganda he has worked with as “visionary and optimistic”, eager to improve their production and not backing down from new technologies or financial risks. When the climate and pandemic allow for it, miners can return to work, and field visits will allow opportunities to identify further adjustments to enhance productivity.

Following up, keep improving.

Once the system is set up, data is collected from the partners on a quarterly basis to keep track of how the operation is developing. Expenditures, consumption, production, and sales are recorded on prepared templates. This is to understand the business dynamics, even when there is a language barrier, but it requires a lot of trust.

That information is then given back to the mines to better understand the bookkeeping and identify nuts and bolts for optimization. At the same time, they keep track of the mining practices in order to ensure better practices are not sacrificed for higher profits.

Based on this record and the trust built, future engagements can include introducing even better equipment, or other steps identified as necessary to improve the production.

To sum it up.

There is no shortage of aspects to be considered when working to reduce the use of mercury, but here are some of the most important ones: understand what the mining communities want, why they want it, what scenario they are operating in, and collect data. Decide together which approach to use, and what tools work best in the given context. Let the facts speak for themselves, instead of pushing anybody to adopt technology they might not be comfortable with. Crucially, finance needs to be available at acceptable conditions, in order to install the equipment. And, follow up on the work done, keep collecting data, and maintain the conversation.

Asked about his favorite aspect of working with mining communities, Cyrus sees it as miners moving from rudimentary equipment to modern technology and getting more for their gold.

“If we can increase their production while still adhering to the responsible mining practices, they can get quite a lot of gold, they can get quite good profit, and their livelihood will be improved.”

It seems that a combination of know-how, finance, and understanding and caring for the context can go a long way to improving the situation for mining communities and their environment.

Want to learn more? The Impact Facility, Solidaridad Network, and Planet Gold held a webinar on mercury and ASM last week that is available here.

About the author
Christian is a Project Manager at Minespider.
Christian Ecker
Christian is a Project Manager at Minespider. He focuses on the implementation of traceability processes and sustainability policies, with an interest in local-level human rights & environmental impacts.

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