A large quantity of slag containing various harmful and heavy metal impurities is generated in non-ferrous metal production industry every year. In order to achieve sustainable development of the industry in Japan during the 21st century, prompt measures should be taken to deal with the ever-increasing quantities of slags. To resolve the slag issues, great efforts have been made to develop their new applications and usage. As a part of the activity of the "Committee for the Investigation Research on Development of Innovative Non-Ferrous Metals Smelting Technologies in the 21st Century", the current situation and problems on this matter are reviewed focusing on slags generated in copper, lead, zinc, and ferronickel production.
