Principles of Metal Refining and Recycling

This book provides a self-contained introduction to the field of purification and recycling of metals. It outlines the unifying scientific principles behind the treatment of various metals and discusses the importance of using a clean and properly alloyed metal. The text covers thermodynamics, physical and transport properties, mixing, mass transfer and numerical models. It describes methods for removal of dissolved impurity elements, particles, and inclusions, and considers important aspects of the solidification process, remelting and adding of alloys. Recycling, future challenges and specific processes for each metal are discussed in detail.

The book is a greatly extended update of the 1992 book Principles of Metal Refining by T. Abel Engh. It includes, in particular, the subjects of metal recycling, ferrous and non-ferrous metal refining, and metalloids like silicon.

Thorvald Engh, Formerly Professor Emeritus, Norwegian University of Science and Technology,Anne Kvithyld, Senior Research Scientist, SINTEF,Geoffrey Sigworth, Consultant, GKS Engineering

Thorvald Abel Engh graduated from NTH in 1958. He has worked at IBM's laboratory for process control, Massachusetts Institute of Technology (MIT), at the Metallurgical Research Station in Luleå, and at the Royal Institute of Technology, Stockholm. From 1971 to 1980 he was a lecturer in Metallurgy Engineering, and from 1980-2004 he was a professor of process metallurgy at Norwegian University of Science and Technology. He continued working in the field of refining and recycling metals up to his death in December 2023.


Geoffrey Sigworth has worked extensively in metals production and refining, melt treatment, alloy design and metal casting. Particular areas of his scientific interest have been the thermochemistry of metallic alloys, control of cast microstructures and characterizing quality in net-shaped castings. Dr. Sigworth was formerly technical specialist for foundry products at Alcoa (Aluminum Company of America); and has extensive experience working for other metal producers as a consultant.

Anne Kvithyld earned her PhD in aluminium recycling at Norwegian University of Science and Technology in 2003. She has worked as a visiting scientist at the Colorado School of Mines and now as a senior researcher at SINTEF, in particular in the field of recycling and refining of metals.

1. The effect of dissolved elements and inclusions on the properties of metal products, Christian Julius Simensen, Otto Lunder, Oddvin Reiso2. Thermodynamics3. Mixing, Mass Transfer, and Numerical Models4. Removal of dissolved impurities from molten metals, Gabriella Tranell, Martin Syvertsen, and Erlend Bjørnstad5. Removal of inclusions from melts, Roderick Guthrie, Sarina Bao, and Mihaiela Isac6. Solidification and Refining, Eivind Johannes Øvrelid7. Remelting and addition of alloy components, Martin Syvertsen8. Metal processes and applications - an overview, Christina Meskers9. Refining in Steel Converter, Olle Wijk10. Recycling, Per Bakke