Depollution: extracting gold naturally with plants
Faced with the dangerousness of gold mining methods by mercury, cyanide or other heavy metals for miners and populations. The mining industry must be active and put in place cleaner solutions with greener methods for the environment.
We are aware that gold is a sector that earns a lot of money. But it is their duty to take care of the planet and protect the people and our environment. Many researchers are working on more environmentally friendly alternative solutions to extract gold from the soil.
What are the different alternative solutions proposed?
Agromine and phitoextraction.
Agromine is emerging. It is the ability of certain plants to accumulate in their tissues high concentrations of minerals without becoming intoxicated. They are “hyperaccumulators”. This feature allows them to be used to decontaminate mining sites and quarries, to extract heavy metals or to practice a new form of agriculture on soils rich in metals.
Some scientists propose to do phytomining. It is a technique for extraction of phytoextraction of gold through plants. They noticed that some natural plants use their roots to extract heavy metals from the soil or air. Metals such as zinc, nickel, cadmium or gold are found in their roots and leaves. For a long time, scientists have studied these hyperaccumulative plants to fight against pollution.
Chris Anderson, an environmental geochemist and expert in gold phytomining at Massey University in New Zealand, has demonstrated that it is possible to obtain mustard plants to suck gold from the soil.
1 / mustard
How does the technology work?
For Anderson, you need to find a fast-growing plant with lots of above-ground masses of greenery, like mustard, sunflower, or tobacco. Then you have to plant them in the ground where there is gold. When the plant transpires, it takes water from the soil’s gold, which accumulates in its biomass, settles on the tiny pores of these leaves. Then, we harvest the plants. Anderson says that getting gold from plants is the easiest part. Gold in plants is gold nanoparticles, which can be of great potential for the chemical industry because it is used as catalysts for chemical reactions.
The use of phytomining, gold can never take the place of artisanal mining.
He explains: “The value of it is in the rehabilitation of polluted mine sites,” he added.
“If we can generate revenue by reframing gold, while soil remediation, then that’s a good result,” said Anderson, who is currently working with researchers from Indonesia to develop a system. sustainable for artisanal small-scale gold miners.
Australian scientists have gold particles in eucalyptus wood. The researchers undertook a study to unravel the mystery of this tree. They carefully studied the leaves, twigs and bark of eucalyptus. It is a tree up to 10 meters high, lying to the south and west of Australia. Through their study, the researchers knew that there were ancient explorations in these places. X-ray analysis reveals the presence of gold particles of about 8 microns (millionths of a meter) in eucalyptus cells. The experiments revealed that these particles were absorbed by the tree roots before being transported to the leaves where the concentrations are higher. Research reveals that eucalyptus is able to fetch gold at depths of over 35 meters.
“We were amazed at the ability of eucalyptus to move gold on a road that is the equivalent of a ten-storey building,” says Melvyn Lintern, a geochemist at the Commonwealth Scientific and Industrial Research Organization in Australia quoted by LiveScience.
But, the amount of gold present in the eucalyptus is extremely small. It would take 500 eucalyptus, growing above a gold deposit, to harvest a lot of gold.
The scientist explains that eucalyptus could serve as a benchmark. They could be used to identify the locations where the gold deposits are located, the depths by the miners. Melvyn Lintern explains that this would be a way to avoid wasting time, money and human resources chasing the precious metal over large areas. For more than 10 years, discoveries of new gold deposits have dropped by 45%.
3 / the wall allyssum
.The mural Alyssum is a plant of the family Brassicaceae. It is a hyperaccumulator plant of nickel up to 100 kg of nickel per hectare. If we can recover nickel with this plant, we can also extract gold.
- 4 / Cornstarch
Researchers at Northwestern University have discovered, by chance, that corn starch is just as effective as cyanide or mercury for gold mining.
By a lucky coincidence, a post-doctoral researcher Zhichang Liu wanted to mix two aqueous solutions. Zhichang had mixed a corn starch derivative with dissolved gold salt. Specifically, the first test tube contained a kind of sugar “alpha-cyclodextrin”, which resulted from the degradation of starch with a bacterium, with another test tube filled with gold. Surprise, tiny needles have formed. Zhichang was saddened because he hoped to see tiny cubic structures that could store gases or other molecules.
“At first, I was disappointed that my experience did not produce cubes, but when I saw the needles, I wanted to learn more about their composition,” says researcher Zhichang Liu in a statement released by his university. . This study was published in the journal Nature Communications.
“Zhichang has come up with the magic formula to insulate gold from anything else in an environmentally friendly way,” said Fraser Stoddart, who oversaw the research.
Passing from sadness to joy, researcher Zhichang Liu had just found the miracle and ecological formula for extracting gold. These needles are an assembly of 4000 nano son of gold ions, trapped by atoms, water and cyclodextrin.
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