Nickel-munching plant to change mining?

Thursday, 8 January, 2015

Rather an interesting piece on on the old scientific discovery front today, as a post on Forbes introduces us to an “astonishing nickel eating plant that could radically change mining.” 

Hot on the heels of yesterday's announcement that forestalled this correspondent's fears of an imminent descent into the post-anitbiotic age (a horrible fate much overlooked in the public narrative), we have what is essentially an ore plant, proving that perhaps money does (almost) grow on trees. Science appears to be winning 2015 so far - long may it continue. 

This plant apparently holds within it the potential “of radically changing how we go about mining for certain metals.” It’s old knowledge that certain plants tend to build up high levels of certain elements within them - the article uses the example of coal, illustrating how elevated levels of germanium in the coal are the result of high germanium concentrations in the plants from which the coal is derived. This new plant, however, catchily names Rinorea niccolifera, is more extreme: a Professor Fernando is quoted as saying that “the Rinorea niccolifera’s leaves can take in up to 18,000 parts per million of nickel. This is a thousand times more than what any other known plant species can safely absorb.”

If true, this has astonishing potential economic implications, as the article points out:

18,000 ppm is also known as 1.8%. So, for one tonne of the leaves of this plant we would have 18 kilogrammes of nickel contained. Well, OK, we would if it had been growing on highly nickel contaminated soil. The importance of this is that those leaves would then be a richer source of nickel that the nickel laterite ores which are expected to be our major source in the centuries to come. These usually grade at around 1 to 1.5% Ni. So our plant, just growing as it wishes to, is concentrating Ni above the sort of level that we’re prepared to dig rock out of the ground to get. And, given that it is in a leaf rather than in rock it’s going to be a lot easier to get out too. Just harvesting the leaves and leaving them to dry will concentrate further, a controlled burning of that dried material further and so on.

And one of the great truths of the mining industry is that the cost of extraction from an ore is more than directly proportional to the concentration of the target metal in the ore. The greater the concentration the less per unit of metal extracted that extraction is going to cost. So, extraction from plants that concentrate to higher than the usual ore level, which are themselves easy to concentrate further, is going to reduce mining costs substantially.

But there’s two more economic effect here too. The first is that this rather frees us from having to go looking for ore bodies, from trying to find places where, say, the nickel concentration of the soil is high. Almost all soil and rock contains just about every element (not true of things like helium but it is true of most metals). Almost always they’re not in the concentrations which make them worthwhile to extract. This is actually the technical difference between the words “dirt” and “ore”. Ore is worth processing for the metals content, dirt is not, even though that dirt will contain some uranium, some gold, some silver, nickel and all of the rest. But if we’ve now got plants that will selectively extract metals from the soil in which they grow then we’ve got a method of extracting valuable metals from just about anywhere, rather than having to go hunt for pre-existing concentrations.

The second effect will depend a little upon whether it will be possible to genetically alter these plants so that they can be directed to a metal of choice. If that happens then the world of weird and exotic metals will change dramatically. I’ve already mentioned germanium, a natural part of all plant tissue but in very low concentrations. When we go looking for Ge (we make certain solar cells and other electronic parts like night sights from it) we end up dealing with things like coal fly ash which have concentrations of perhaps 500 ppm, maybe 800 ppm. If we’ve now got a plant that can concentrate Ge in its tissues up to that sort of 18,000 ppm level then we can produce that metal a great deal more cheaply (currently it’s around $1,500 a kg, or was last time I looked). And the same will be true of a great number of other metals. There are all sorts of metals that we extract from rock when we’ve a concentration of perhaps 500 or 1,000 ppm in that original rock. If we can get plants, selectively, to do that extraction for us up to concentrations that this plant can do for nickel then we’re on the verge of changing the economics of mining entirely.

Check out the original piece here.