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A new source for rare elements

Researchers have found a new possible source of rare elements - waste from a phosphorescent rock - and an environmentally friendly process to extract them from it, according to a new study. The approach could benefit the development of clean energy technologies

Scheme describing the extraction mechanism of the rare elements by several acids
Scheme describing the extraction mechanism of the rare elements by several acids

[Translation by Dr. Nachmani Moshe]

rare elements (Wikipedia entry), for example neodymium (neodymium) and dysprosium (dysprosium) are essential for technologies of utilizing solar and wind energies as well as for advanced technologies in vehicles, alongside modern electronic components, such as those found in smart phones. However, a reduction in the rate of production of rare elements in the US endangers the energy security of the US. Compared to the USA, China produces about ninety percent of all these elements in the world.
The extraction of these elements from phosphogypsum - the waste obtained from the process of phosphoric acid production - may be a solution to this problem. It is estimated that every year 250 million tons of phosphoric rock are mined for the production of phosphoric acid used in the preparation of fertilizers. The US mined about twenty-eight million cubic tons in 2017. Rare elements typically make up less than one-tenth of a percent of phosphate rock. However, around the world, about a hundred thousand tons of these elements are found in phosphogypsum waste. This amount is almost equal to the amount of one hundred and twenty thousand tons of rare element oxides produced annually throughout the entire world.

Common methods of extracting rare elements from lead involve the production of millions of tons of toxic and acidic pollutants. However, instead of using dangerous chemicals to deplete these elements, another method may make use of organic acids produced by bacteria, the researchers said. The research team examined the possibility of using mineral and organic acids, including a mixture of bio-acid, for the extraction of six rare elements (yttrium, cerium, neodymium, samarium, europium and ytterbium) from synthetic phosphogypsum.

Oxides of the rare elements gadolinium, praseodymium, cerium, samarium, lanthanum and neodymium [Photo: USDA ARS]
Oxides of the rare elements gadolinium, praseodymium, cerium, samarium, lanthanum and neodymium [Photo: USDA ARS]

The researchers prepared a mixture of bio-acid, consisting mainly of gluconic acid, which is naturally found in fruits and honey, by growing dedicated bacteria on a substrate of the sugar glucose. The results indicate that indeed the bio-acid led to a better performance in the extraction of rare elements than the performance of pure gluconic acid at the same acidity level (pH = 2.1. The mineral acids sulfuric acid and phosphoric acid did not manage to exhaust the rare elements at all under the same conditions. When the four acids were tested At the same concentrations, only the sulfuric acid was more effective than the bio-acid.
In the next step, the researchers plan to test the performance of the bio-acid on industrial phosphogypsum and other types of waste obtained during the production of phosphoric acid, products that also contain varying amounts of rare elements. As part of their initial experiments, the researchers looked at lab-made phosphogypsum, so they could easily control its exact composition. Samples obtained in industry are much more complex.

The article is about the research

The news about the research

4 תגובות

  1. The Chinese caught the rest of the world in an exercise that in any orderly market constitutes a violation of the law: they lowered the prices of rare metals until all the mines in the world were closed, then they nationalized all the mines in China and raised prices 50 times.
    In the meantime, there are two new sources: one is already active today, the production of rare metals in the recycling of old fluorescent bulbs, which are now being replaced at a rapid pace by LEDs. There is a company in the USA that does the recycling and produces about a third of the consumption in the USA.
    Future source: The Japanese found a huge deposit of rare metals, at a depth of 6 km below sea level. The deposit is expected to supply the world's consumption for about 700 years.
    Besides, the shortage is temporary. In a few years, new mines will be opened, because the rare metals are not really rare on the earth's crust.

  2. It sounds very strange to me that phosphoric acid (H3PO4) is used for extraction from phosphate rocks (= phosphates)...

  3. I assume that phosphate waste in Israel can also be reprocessed in this way.
    Does anyone have detailed information on this?

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