Zhijiang Gao
Ph.D. student of Kroll Institute for Extractive Metallurgy at Colorado School of Mines

Zhijiang’s doctoral research at KIEM focuses on the removal of Cu impurities from shredded automobile scrap, involving physical sorting improved by machine learning and thermo-chemical processing under molten state. He has been accepted for publishing work “Applying Improved Optical Recognition with Machine Learning on Sorting Cu Impurities in Steel Scrap” in the Journal of Sustainable Metallurgy. He worked with Dr. Patrick Taylor on the Pushing the State of the Art in Steel Recycling through Innovation in Scrap Sorting and Impurity Removal REMADE Project. We asked him about his experience:

Q: How did you become interested in steel recycling?
A: Before participating in the REMADE project, I knew that steel is the most recycled material in the world and it maintains a high recycling rate. Millions of metric tons per year of automobiles, appliances, and other steel products have been recycled by the steel industry. I then learned about the primary issue still limiting steel recycling is the surface hot shortness during hot working induced by Cu contaminants. I became interested in steel recycling when I realized how much work researchers have done to try to eliminate this issue. It could be a great opportunity if we can contribute our efforts to the progress of improving steel recycling.

Q: How has your experiences working on a REMADE project changed your understanding of the issue?
A: With the access to actual automobile scrap and following identification piece by piece, we have stepped through the recycling of automobile scrap and understand the reason for Cu accumulation and contamination. Through exploratory experiments, we think the application of new sensor technology could be feasible for sorting the impurities out in an efficient way. All these experiences not only provided me with thorough details, but also made me think that to solve the issue, technical and economic factors must be evaluated at the same time, especially for recycling and recovery.

Q: What’s your advice for the new generation of students considering careers in Recycling and Recovery?
A: “No such thing as waste, only resources in the wrong place.” I think this could be the ultimate target for recycling and recovery. With the development of the circular economy, recycling would be of paramount importance, as well as the training of engineers and participants who have a passion in this for a career.