A group of scientists are exploring an alternative technique of recovering rare-earth minerals from old phones and laptops, which will reduce the impact of mining and processing rare earths on the environment, according to a member of team of researchers,Senior Research Fellow, Deakin University.
“Our team in collaboration with the research centre Tecnalia in Spain has developed a way to use environmentally friendly chemicals to recover rare-earth metals. It involves a process called “electrodeposition”, in which a low electric current causes the metals to deposit on a desired surface,” writes Pozo-Gonzalo in an article published by The Conversation.
“Rare-earth metals are critical to the high-tech society we live in as an essential component of mobile phones, computers and many other everyday devices. But increasing demand and limited global supply means we must urgently find a way to recover these metals efficiently from discarded products.”
Rare-earth metals are currently mined or recovered via traditional e-waste recycling. But there are drawbacks, including high cost, environmental damage, pollution and risks to human safety. This is where the ongoing research comes in.
Ponzo-Gonzalo believes the process is important because if it is rolled on a commercial scale, it can alleviate the pressure on global supply, and reduce reliance on mining.
Rare-earth metals are currently extracted through mining, which comes with a number of downsides, Ponz-Gonzalo points out.
First, it’s costly and inefficient because extracting even a very small amount of rare earth metals requires large areas to be mined.
Second, the process can have enormous environmental impacts. Mining for rare earth minerals generates large volumes of toxic and radioactive material, due to the co-extraction of thorium and uranium — radioactive metals which can cause problems for the environment and human health.
Third, most mining for rare-earth metals occurs in China, which produces more than 70% of global supply. This raises concerns about long-term availability, particularly after China threatened to restrict its supply in 2019 during its trade war with the US.
Pozo-Gonzalo observes that e-waste recycling is not the complete answer.
“Through e-waste recycling, rare-earth metals can be recovered from electronic products such as mobile phones, laptops and electric vehicles batteries, once they reach the end of their life.
“For example, recovering them from electric vehicle batteries involves traditional hydrometallurgical (corrosive media treatment) and pyrometallurgical (heat treatment) processes. But these have several drawbacks,” she says.
Pyrometallurgy is energy-intensive, involving multiple stages that require high working temperatures, around 1,000℃. It also emits pollutants such as carbon dioxide, dioxins and furans into the atmosphere.
Meanwhile, hydrometallurgy generates large volumes of corrosive waste, such as highly alkaline or acidic substances like sodium hydroxide or sulfuric acid.
Similar recovery processes are also applied to other energy storage technologies, such as lithium ion batteries.