Study looks into biochar for battery recycling

A research project at the University of Minnesota is studying the use of biochar in pyrometallurgical battery recycling.

NRRI’s Eric Singsaas and Brian Barry (left) talk with Gopher Resource’s James Dahlstrom and Abbas Mizia in an NRRI Lab.

Battery recycler Gopher Resource is teaming up with the University of Minnesota Natural Resources Research Institute (NRRI) in Duluth to study the use of charcoal from biomass as an alternative to fossil coal in its recycling process.  

Gopher Resource recycles more than 25 million batteries a year, producing about 300,000 tons of recycled lead for reuse in domestic manufacturing.  

Historically, conventional charcoal was used in pyrometallurgical operations as a fuel source and reductant to produce metals like cast iron or copper. During the mid-1800’s charcoal was replaced by coal or foundry coke that had properties better suited for the applications. 

Advances in technology have allowed researchers to better understand how these carbon-based materials impact performance in smelting processes. As a result, highly engineered charcoals like biochar may again be a viable, cost-effective reagent.  

Biochar is created by combusting organic materials in a low oxygen environment using processes like pyrolysis or torrefaction to produce a black material (biochar) that is about 70% carbon. Biochar is often used in soil amendment applications to remove biological contaminants and improve nutrient retention.  

The project with NRRI will explore the use of biochar as a replacement for coke currently used in the company’s furnace process.  

“Our role is to figure out how to make biocarbon work for their process,” explained Eric Singsaas, NRRI materials and bioeconomy group leader.

“We can densify the biocarbon with binding agents and give it the right chemical properties by optimizing the process conditions.” 

The goal is to reduce Gopher Resource’s direct greenhouse gas emissions by up to 30% using a renewable, carbon-neutral resource such as biochar that will significantly increase the sustainability of the lead recycling process. 

In this case, the biochar is produced using ash trees and balsam fir slated for removal due to disease and insect infestations, such as emerald ash borer and spruce budworm. Finding a useful application for this abundant resource will not only divert waste from landfills but will aid in the prevention of wildfires in northern Minnesota.  

“We are very conscious of recycling process waste and have a number of projects aimed to improve sustainability. Reduction of our net carbon footprint is one such example, and why we have partnered with NRRI to explore renewable alternatives,” said James Dahlstrom, senior director of engineering and technology at Gopher Resource.

“We are optimistic that biochar has the potential to create a renewable supply chain that will reduce our net greenhouse gas (GHG) emissions significantly.”  

With funding from the U.S. Department of Defense, the project is part of a larger Materials Recovery Technology for Defense Supply Resiliency (MRT-DSR) initiative, a multi-year collaborative partnership working to find new ways to reduce waste and recover more useable materials in metals processing.