“Mining” and “environmentally friendly” rarely come in the same sentence. The gaping holes, polluted rivers, spewing smokestacks and toxic soil associated with mining are some of the reasons why.
But if it’s successful, an experiment by nickel mining giant Inco Ltd. of Toronto could change that. In conjuction with Viridian Resources LLC of Houston, Inco has planted alyssum near a former metal refinery in a small Southern Ontario town called Port Coborne to test the viability of phytomining — extracting metals from soil and rock using plants.
Alyssum has evolved the ability to absorb metals such as nickel. Tests indicate that a crop of alyssum can contain up to 2% nickel. To extract the metal, Inco will use a furnace to produce a metallic ash. An added environmental benefit is that the incineration process can be used to generate power.
Natural wonder — with a few tweaks
Since the 1940s, researchers have known of alyssum’s ability to concentrate nickel and other metals.
But wild alyssum concentrates just a fraction of the nickel of plants used for phytomining. Thanks to selective breeding, researchers have improved the plant’s absorption and concentration.
Add to that an increasing body of knowledge about phytomining, and returns improve even more. Scientists now know, for example, that alyssum contains the most nickel before it goes to seed.
While phytomining will have many enviromental benefits, this is no charity work.
According to the US Department of Agriculture, a harvested crop of nickel-rich alyssum would be worth up to $3,000 a hectare if the incineration process were also used to generate power ($2,000 if it weren’t), assuming a nickel price of $5,000 per tonne. By contrast, a food crop on the same land — if it could be grown at all, given the soil conditions — would yield about $50 to $100 per hectare.
And lots of land qualifies. It takes just 0.05% nickel in soil to allow alyssum to produce a valuable nickel yield. In some places, such as Indonesia (where Inco and Viridian hope to open a phytomine soon) natural levels of 0.5% are common. With proper soil management, this would allow a phytomine to operate for centuries.