February 2015    Print this article

The end of mercury mines

Louis Bienvenu, ing. and Katrie Bergeron, ing.
Ministère de l’Énergie et des Ressources naturelles

On October 10, 2013, Environment Canada announced that Canada had signed the Minamata Convention. This treaty is the result of negotiations between 140 countries, under the aegis of the United Nations.

The goal of the Convention is to reduce human exposure to mercury to a minimum. The main measures of the treaty aim to…

  • reduce the supply of mercury (supply sources);
  • ensure the environmentally sound storage and international trade of mercury;
  • reduce the intentional use of mercury: products and processes that use mercury (for example, dental amalgams);
  • eliminate the use of mercury in artisanal and small-scale gold mining; and
  • reduce mercury discharge into the environment: air, water and land, mercury waste, contaminated sites.

The Convention stipulates that products using mercury, such as thermometers, should disappear by the year 2020. The states agree not to authorize the opening of any new mercury mines, and a delay of 15 years is granted to close existing mercury mines and stop the use of mercury in artisanal mining activities.

Mercury poisoning at Minamata

The Convention is named after the city with the same name in Japan, in remembrance of the worst case of mercury poisoning. From 1932 to 1966, approximately 400 tons of mercury were discharged into Minamata Bay from a chemical factory. 

The subsequent mercury poisoning primarily affected fish, then cats, then children who lost the ability to speak and could no longer walk or eat, and finally pregnant women who passed along the disease to their children. Officially, 13,000 people (of which 9,000 died) were victims of this spillage.

Use of mercury

Worldwide consumption of mercury is roughly 2,000 tons per year, half of which is used in China for the production of vinyl polymers for paints, glues and other products of that nature. Mercury is also used by artisanal gold panners and in a number of modern products, such as dental amalgams, breakers, fluorescent bulbs, medical and laboratory instruments, batteries, seed treatments, antiseptic and antibacterial creams, and skin-lightening creams.

Mercury mines

The only mercury mine in Canada, the Pinchi Lake mine in British Columbia, ceased operations in 1975. It operated from 1940 to 1944, and from 1968 to 1975. There has never been a mercury mine in Québec, and there is currently no exploration work towards developing a mercury mine.

In 2011, China was the leading producer of mercury with 72% of the world’s production, followed by Kyrgyzstan with 13%. These are the only remaining countries that still have mercury mines. The other 15% of production is from recycling or as mining by-products. China signed the Minamata Convention, but Kyrgyzstan has not yet signed.

Two main sources of mercury

The biggest emitters of mercury into the environments are coal-fired power plants and artisanal gold mining.

Coal-fired power plants

Power generation from coal plants is widespread throughout the world, following the pattern of coal deposits. For example, it accounts for 75% of energy production in China, and 50% in the United States. As there is approximately 1 mg of mercury in every kilogram of coal, the use of this material emits large quantities of mercury into the air. In the United States only, 600 power stations emit some 50 tons of mercury into the air. In China, more than 100 tons of mercury enter the atmosphere every year.

Pursuant to the Minamata Convention, states are obliged to measure their emissions and develop a plan of action to reduce them. The United States have declared new rules concerning atmospheric emissions, including mercury, for coal-fired power plants. According to experts, setting up new rules will prevent 11,000 premature deaths in the United States caused by toxic emissions from power plants.

The new American rules directly affect the principal technology that controls mercury emissions from coal-fired power plants, the injection of activated carbon. Last July, the firm Roskill reported that worldwide sales of activated carbon were growing rapidly, and by 2017 it would need to increase its production to keep up with demand.

Artisanal gold mining

Extracting gold using mercury is still widely practiced in the artisanal mines of Latin America, Africa and Oceania.

The technique consists of processing gold-bearing mud with mercury to form amalgam (an alloy between mercury and another metal), then heating the amalgam to evaporate the mercury and liquefy the gold.

Gold panners are thus doubly exposed to mercury: while they mix the ore with bare hands, and when they burn the amalgam to recover the gold. Experts estimate that this method exposes between 10 and 15 million gold panners around the world to toxic doses of mercury vapour. Nearly 50% of these people would have developed neurological systems that are characteristic of mercury poisoning.

On a global scale, the practice of gold panning produces atmospheric emissions of mercury amounting to roughly 300 tons per year.

In Peru — the fifth largest mercury producer in the world — artisanal miners produce 18 tons of gold per year and discharge 32 tons of mercury into rivers. This unregulated segment of Peru’s mining industry provides a livelihood for 40,000 gold washers and their families.

Under the Minamata Convention, the states with land that is being used for artisanal and small-scale gold mining and recovery must take measures to reduce, and if possible eliminate, the use of mercury and mercury compounds in these activities. Peru has signed the Minamata Convention.

But there is still hope for Peruvian gold panners. In 2010, a group of Peruvian professionals designed and manufactured equipment that does not require mercury to extract gold. The apparatus, known as “ECO-100V”, was successfully tested, recovering 95% of the gold and recycling 90% of the process water. Furthermore, it only consumed 0.2 litres of fuel for the production cycle. The $5,000 price tag is equivalent to two months of work for a gold panner.

This apparatus works using a small thermal motor that creates millions of miniscule bubbles that separate gold from black sand and make the gold float. The process is so efficient that it recovers up to 20% more ore compared to conventional methods using mercury. This should be a good incentive for artisanal gold producers.

Impact of the Convention on the MERN
and mining development

Certain features of the Convention are relevant to the MERN:

  • Art. 3 – mercury mining activities must not be allowed in the province.
  • Art. 12 – appropriate strategies must be developed to identify and assess sites contaminated by mercury and remediate them.
  • Art. 21 – measures taken to apply the Convention shall be reported, in addition to their effectiveness and possible challenges in meeting the objectives of the Convention.

At the present time, the means for applying this Convention to the province of Québec have not yet been defined, particularly for the mining sector, but authorities have been appraised of the situation. As the MERN must report on measures taken to apply the Convention, it will need to inventory mining sites contaminated with mercury, and develop and action plan to rehabilitate them.

On the other hand, the prohibition on allowing mercury mining activities does not affect the province’s development of its natural resources because no such activities are planned in the future. It is possible, however, that this authorization ban may require a modification to the Mining Act.

One fact remains: it is the first time as a signatory of an international treaty that Canada, and thus Québec, cannot allow the mining of a mineral substance. 

For more information : http://www.mercuryconvention.org/

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© Gouvernement du Québec, 2013