From toxic waste to valuable rare earth resources

(CLO) Millions of tons of coal ash from burning fossil fuels are currently being buried, threatening to seep into water sources and pollute the soil. However, these toxic wastes can also become valuable resources, containing rare earth elements necessary for clean energy development.

Scientists have studied coal ash from power plants across the United States and found that it could contain up to 11 million tons of rare earth elements, equivalent to nearly eight times the US rare earth reserves, with a value of about $8.4 billion, according to a recent study led by the University of Texas (UT) at Austin.

Bridget Scanlon, study author and professor in UT’s Jackson School of Earth Sciences, said the resource represents a huge opportunity to extract rare earth elements domestically without having to mine them further. “This really exemplifies the saying ‘turn trash into treasure,’” she said. “We’re trying to close the loop and use waste to recover resources.”

Rare earth elements, including scandium, neodymium and yttrium, play a key role in clean technologies such as electric vehicles, solar panels and wind turbines. While these metals are not rare in nature, they are difficult to mine and separate from ore, leading to demand far exceeding supply.

Coal ash on the surface of the Dan River in Virginia, US, after a terrible coal ash spill. Photo: AP

As the world shifts to clean energy to combat global warming, demand for rare earth elements is expected to surge, possibly seven times current levels by 2040, according to the International Energy Agency.

Research shows that the ease of extracting rare earth elements from coal ash depends on its source. Coal ash from the Appalachian Basin in the United States contains the highest concentration of rare earth elements, but is only 30% extractable. Meanwhile, coal ash from the Powder River Basin in Wyoming and Montana has lower concentrations of the elements but is 70% easier to extract.

However, Paul Ziemkiewicz, director of the Water Research Institute at West Virginia University, warns that extracting rare earth elements from coal ash can be expensive, as the process requires the use of strong acids and bases, which are expensive and can have negative environmental impacts.

In addition, mining rare earth elements from coal ash cannot change the amount of waste that needs to be treated, because coal ash contains many dangerous pollutants such as mercury, arsenic and lead.

Still, the study authors argue that the benefits of recovering rare earth metals could offset the costs of improving how coal ash is stored and managed. In April, the Biden administration announced a $17.5 million investment in projects to extract rare earths from coal ash.

Some worry that using coal ash to mine rare earth metals could spur more coal mining, a highly polluting fossil fuel. Scanlon is not too worried about that, however, saying the resource will mostly come from old waste, since there are already more than 2 billion tons of coal ash stored across the US.

The Department of Energy has said using coal ash as a feedstock for critical materials would discourage further coal burning. Ms Scanlon said the broader goal is to extract value from coal without burning it, including finding other ways to recover products from coal beyond rare earths.

Ngoc Anh (according to CNN)

Source: https://www.congluan.vn/tro-than-tu-chat-thai-doc-hai-thanh-tai-nguyen-dat-hiem-quy-gia-post324558.html