I had a friend share an interesting article from Mining.com with me. The article asked this question: “Can plants that suck metal from the soil replace mining?” It’s an interesting thought. We eat plants every day for their mineral content, but actively growing plants that contain massive amounts of minerals such a nickel and extracting that mineral for industrial purposes? This is agro-mining.
The article noted that miners have this saying: if it can’t be grown, it must be mined. Yet mining is devastating for our planet and environment. If we are to solve this, we need to use renewable technology which depends on obtaining more and more of these minerals and metals from the ground. It sounds like a vicious cycle — and it is — but the idea of growing plants specifically to absorb the metals through the soil is pretty inventive.
This is what agro-mining is. The article shared a video from Bloomberg that explored whether or not agro-mining would ever be scalable enough to reduce traditional mining practices. The video explained that the demand for metals is rising more and more strongly, especially in the year after the pandemic started. Everything from household appliances to manufacturing electric cars to building bridges or highways requires metals.
Nickel mining has been increasing since the early 2000s, mostly due to China’s economic boom. The rise of electric vehicles is also playing a key role in the demand for nickel.
The video also noted that for the past 30 years, researchers from all over the world have been pursuing agro-mining. Agro-farming, also known as phytomining, is simply growing plants that can store metals such as zinc and then later harvesting them. Researchers have worked on recovering zinc, rare earth elements, and even cobalt using these methods.
The video noted that mining has many devastating effects on the environment, ranging from acid rain to air pollution. In 2020, Elon Musk announced that Tesla was looking for nickel that was mined sustainably. Yvonne Yue Li with Bloomberg News pointed out that nickel, not steel, has the highest CO2 emission intensity.
“You may think steel is the most polluting metal when it comes to CO2 emission intensity, but actually nickel has the highest CO2 intensity of all metals. CO 2 emissions per ton of metal for nickel production on average is about 18 tons of CO2 per ton of metal.”
The processing, smelting, and refining of nickel also result in the highest CO2 emissions of mined metals. Li noted that the mining industry is trying to focus on making nickel mining more sustainable. She pointed out an example of plants using renewable energy and hybrid systems as a fuel source. However, the mining industry as a whole is pretty slow compared to other industries.
Mining is just a very energy-intensive activity. As stated in the video, if there’s a mine with 1% copper, then 90% of the materials will be waste materials.
The video also interviewed Dr. Antony Van Der Ent from the University of Queensland, who is one of the key researchers of agro-mining.
“Hyperaccumulators are a rare group of plants that have the unusual ability to accumulate very high concentrations of particular metals into their living shoots, so into their leaves. We know of about 700 of them that occur all around the world.
“And most of them are known for nickel — 500 or so of them. We know hyperaccumulators for a whole range of different metals, including thallium and zinc, and copper, cobalt, manganese. But we keep discovering more of these plants wherever we do research.
“So it is about 350,000 plant species around the world, and we think there are more hyperaccumulators that are awaiting discovery.”
How do these plants accumulate metals? A nickel hyperaccumulator plant literally consumes the metal from the soil through its roots. Then it stores the metal in the skin of its leaves or biomass. Once the plants are harvested, the biomass is then dried and incinerated. The ash created by burning the plants is ready for processing to create a bio ore. Nickel is then recovered from the bio ore.
The ash contained up to 20% of nickel, which is more than any nickel ore on the earth. The video shared exactly how it’s processed or extracted from the ash. The video also goes into detail about the plants, how they are bred and grown. These plants are also used to decontaminate polluted soils that have massive amounts of lead, zinc, or other metals in them. One of the plants that were featured in the video has leaves that can contain up to 4% of nickel in dry weight. Incinerating the plants does use energy, but the team’s tests have discovered that the overall agro-mining process uses significantly less energy than conventional mining procedures.
You can watch the full video here.
I think this is a brilliant way to recover metals (and minerals) that are used for industrial purposes as well as other purposes such as health or medicine. I think that we need a company that will do what Tesla did for the auto industry to do figure out a way to scale up agro-mining. This could revolutionize the mining industry while also helping to clear up soils that have been contaminated by metals such as lead. We’ll keep an eye on what happens in this sector and if it becomes cost competitive with conventional mining at some point at a decent scale.
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