Young-Shin Jun, a professor at the University of Washington has found a way to extract rare earths from coal fly ash, a fine powdery waste product of coal combustion.
In virtually all modern electronic devices, such as mobile phones, computers, televisions and even vehicles of all kinds, rare earth elements (REEs) are used, which comprise a group of 17 metallic elements.
Despite the fact that the demand for these elements has been increasing every year and, in fact, it is vital for the electric car industryits offer is limited by geopolitical factors and its extraction is carried out through environmentally unsustainable practices.
To address this problem, the professor of energy, environmental and chemical engineering at the McKelvey School of Engineering at the Washington University in St. LouisYoung-Shin Jun, together with his team, have developed a proof-of-concept solution that involves extracting REEs from coal fly ash, a fine powdery residue produced by coal combustion.
“We wanted to use a greener process to extract REE than traditionally more harmful processes”states Jun. “Since the charcoal has already been used, this process is ultimately a pathway to waste product reduction and remediation.”
How to extract rare earths from coal dust
The teacher Young Shin Jun and his former PhD student, Yaguang Zhu, now a postdoctoral fellow at Princeton University, have developed an innovative extraction process using supercritical fluid.
This is a substance that is in a state between liquid and gas when exposed to a temperature and pressure above its critical point. This method, commonly used to decaffeinate coffee, allows critically necessary REEs to be recovered from coal fly ash that would otherwise have been disposed of in a landfill.
According to Jun’s team, more than 79 million metric tons of ash coal flywheels each year in the United States, and the potential value of REEs that could be extracted from them is estimated at more than $4 billion annually.