Industrial Super-MineDNI Metals’ breakthrough technology pioneers mining industry’s green revolution
May 25, 2010
By Jesse J. Leaf
For Troy Media
CALGARY, AB, May. 25, 2010/ Troy Media/ — It sounds like somethingout of a science fiction movie: Bacteria exist in an alien environmentand multiply by eating rock and living off their own heat and acidwaste, leaving only valuable metals in their wake.
Well, it’s not science fiction, but science fact that may soon beunfolding in the vast black shale mountains of northern Alberta. Calledbio-heapleaching, this emerging technology is being pioneered in Canadaby DNI Metals Inc., a small Toronto company that just mightrevolutionize the mining industry.
Bio-heapleaching — the future of mining
With industrial leaders and innovators looking for better, greenerways of keeping the world’s economy churning, DNI believesbio-heapleaching is the future of mining, a sustainable technology thatis easier on the environment, cheaper to operate, and will yield metalsthe future will desperately demand.
DNI is conducting tests to see how bio-heapleaching can be used inAlberta black shales. It sees the technology as the foundation for anindustrial super-mine north of Fort McMurray, AB, where it has rights toa vast polymetallic store of minerals on 2,500 square-kilometres ofland in the heart of Alberta’s oilsands country.
If you break the name apart, you get to the astounding science behindit. A solution made up of naturally occurring bacteria captured fromthe black shale is dripped through heaps of low-grade ore that leach outusable minerals.
The process works in several stages that bridge the gap betweenbiology and chemistry. According to Karen Budwill, a microbiologist atAlberta Innovates – Technology Futures (an arm of the Alberta governmentpreviously known as the Alberta Research Council), “It’s a biologicalsystem that’s creating a chemical reaction.”
A simple beginning
“Bioleaching has its roots in the 1970s,” says Shahe Sabag, DNI’spresident and chief executive officer. “It was primarily used for copperand hard to recover gold-bearing ores.”
It then took more than a decade to invade the world inhabited by thebacteria living in ore rock to discover what their private lives wereall about. It is a complicated society.
Oneof the environmental benefits of a bio-heapleach metals mine is that itconsumes massive amounts of sulphur during normal operations. Thebright yellow sulphur pyramids stockpiled in this aerial photo near FortMcMurray, Alberta, are part of the waste byproducts created when heavyoil is upgraded. Photo courtesy: DNI Metals Inc.
“There are about a dozen different species of bacteria,” says Sabag,“all with different needs – temperature and moisture levels, forexample. To find just the right ones to cultivate took time. It’s likemaking yogurt; it’s bacteria. And it took years to perfect yogurt,” hesays with a smile. “Empirical science can only take you so far.Sometimes you need a lot of trial and error in the lab to get answers.”
This spring DNI got some of those answers. Results of leaching testsconducted at independent laboratories in Canada and France showedsignificant recovery of metals from the black shale. Actlabs, ofAncaster, Ont., pulled a cocktail of metals from the rock includingnickel, copper, cobalt, cadmium, uranium, lithium, vanadium, molybdenumand zinc in 24-hour and 36-hour leaching tests.
The Bureau de Recherches Géologiques et Minières is France’s leadingEarth sciences institution. Its labs also demonstrated that metals canbe readily extracted from the black shales via bioleaching, showingrecoveries high enough to compel expansion of the test program.
Sabag says the test results are a milestone step toward development of what he calls the Alberta Black Shale Metals project.
Finnish firm Talvivaara pioneered the first bio-heapleachingpolymetallic mine in 2008. Today, the company is recovering commercialquantities of nickel, cobalt, copper, zinc and manganese, building itsstable of recoverable metals one by one from what were once uselessdeposits. Talvivaara recently added uranium to its stable ofrecoverables and forecasts enough supply to satisfy almost all ofFinland’s nuclear industry needs. Talvivaara is projecting a profitablefuture that will generate tens of billions of dollars over the next 75to 100 years and with minimal operating costs or damage to theenvironment. Talvivaara spent about $750 million to get its mine up andrunning. Operating expenses are low compared to traditional miningmethods because bio-heapleaching uses steady state production – theprocess never ends and there are no energy bills to pay.
Energy of creation
Down at the microbial level, the process vibrates with the energy ofcreation. A dilute solution containing bacteria native to the rock issprayed over the heap, percolating through its core.
Here’s where it gets interesting. With their living and reproductiveconditions set to paradise, the bugs go busily about living the goodlife, dining on the iron and sulfur they relish, excreting powerfulchemicals that liberate the metal compounds DNI is after. Sabag says DNIhopes to extract copper, silver, nickel, zinc, and uranium. DNI’sproperty also holds lithium, molybdenum and vanadium, minerals that areexpected to be in great demand for electric cars that can be recoveredthrough this process. Leaching solutions are washed to the bottom of theleach pile to be collected and circulated back to the top of the heap.This is done a dozen times over until the solution is so pregnant withmetals that it can be siphoned off and sent to a metal-separationsplant. The spent liquid is recycled to the top of the pile, to whichfresh rock is added, and the process continues without stop for decades.
Sustainable solution
It’s all part of what Sabag calls the sustainable advantagesbio-heapleaching has over traditional mining methods that use toxicchemicals and energy intensive smelting and refining processes. Thechemical and biological reactions in bio-heapleaching areself-sustaining, operating in what is effectively a closed system thatuses only air, water, sulphur and the native rock and bacteria. Spentbyproducts are recycled back into the system so there are no wettailings. There’s no power needed to fuel the system.
The heat the pile generates keeps it operating in virtually anyambient air temperature. The pile requires industrial amounts of sulphurthat is tilled and dripped into the heap to fuel the chemical reactionswithin and keep its pH levels in balance. DNI’s property is adjacent toAlberta’s oilsands mining operations that produce thousands of tonnesof sulphur as a waste byproduct of refining the heavy oil. Abio-heapleaching operation could be used to eat up those massive storesof waste sulphur.
“You have to have the proper acidity and temperature conditions tomake the culture conducive for the bugs to be happy and grow,” says Dr.Budwill.
The composting nature of the bio-heap is even being tested for itsproperties as a carbon sink, ultimately consuming greenhouse gasemissions created elsewhere. Dr. James Brydie is a research scientist atAlberta Innovates. He is working on the question of carbonsequestration, which is a fancy term for locking CO2 away permanently soit doesn’t get into the atmosphere. “We are studying the effect ofusing CO2 both in the mining process and as a permanent sink in thecrushed ‘spent’ shale. This can be potentially used as backfill,” hesays.
In today’s world, satisfying regulations means the ecological impact of such a project must be parsed to the nth degree.
Jeremy Moorhouse, an eco-efficiency analyst for the Pembina Institutein Calgary, Alta., an environmental think tank, says a detailedlifecycle analysis must be performed covering the environmental impactof the facility. “The study runs the full gamut — includinggreenhouse-gas emissions and water use — from construction of thefacility to its deconstruction,” he says. “You have to determine whatthe strata produces and the scale of its impact per kilogram. You thenhave to look at how to reduce that impact, as well as how it can beincorporated into other projects.”