The Massachusetts Institute of Technology, Cambridge, announces that associate professor of metallurgy Antoine Allanore has received a $1.9 million grant from the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy to run larger scale tests of a new way to produce copper using electricity to separate copper from melted sulfur-based minerals, which are the main source of copper.
In June 2017, researchers in Prof. Allanore’s lab identified how to selectively separate pure copper and other metallic elements from sulfide mineral ore in one step. Their molten sulfide electrolysis process eliminates sulfur dioxide, a noxious byproduct of traditional copper extraction methods, instead producing pure elemental sulfur.
“We think that with our technology we could provide these copper wires with less energy consumption and higher productivity,” Prof. Allanore says. It may be possible to cut the energy needed for making copper by 20 percent.
In earlier research, postdoc Sulata K. Sahu and graduate student Brian J. Chmielowiec decomposed sulfur-rich minerals at high temperature into pure sulfur and extracted three different metals at very high purity: copper, molybdenum, and rhenium. The process is similar to the Hall-Héroult process, which uses electrolysis to produce aluminum, but operates at a higher operating temperature to enable production of liquid copper.
Currently, it takes multiple steps to separate out copper, first crushing sulfide minerals, and then floating out the copper-bearing parts. This copper-rich material — copper concentrate — is next partially refined in a smelter, and further purified with electrolytic refining.
“Professor Allanore’s approach would work on the copper concentrate and has the potential to produce copper rod in a single operation while separating unwanted impurities and recovering valuable byproducts that are also in the concentrate,” says Hal Stillman, director of technology development and transfer for the International Copper Association. “Professor Allanore’s approach is a big step; it allows a completely new approach to refining copper.”
The three-year, $1.89 million DOE award will allow Allanore’s group to make a larger reactor, producing about 10 times as much liquid copper per hour, and to run the reactor for a longer time, enough to identify what happens to the other metals accompanying copper, which are also commercially important.
