Proposal for Excavation of Urban Mines and Recycling of Artificial Ores
Creation of a Visible Resource Recycling Chain by Applying Technology to the Intermediate Process in Recycling
National Institute for Materials Science
NIMS proposed a new direction for resource use which he calls "recycling of artificial ores" at the session on "Resource and Environmental Policy" at the 2008 Spring Meeting of the Mining and Materials Processing Institute of Japan (MMIJ) held at the Institute of Industrial Science of the University of Tokyo on March 27.
Abstract
- Dr. Kohmei Harada, Managing Director of the Innovative Materials Engineering Laboratory and Managing Director of the Strategic Use of Elements, Interdisciplinary Cluster at the National Institute for Materials Science (hereinafter, NIMS; President: Teruo Kishi) proposed a new direction for resource use which he calls "recycling of artificial ores" at the session on "Resource and Environmental Policy" at the 2008 Spring Meeting of the Mining and Materials Processing Institute of Japan (MMIJ) held at the Institute of Industrial Science of the University of Tokyo on March 27. The proposal was presented jointly in the names of Dr. Harada and Dr. Mikio Kobayashi, Deputy Director of the Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology.
- The term "urban mines" refers to the valuable metals contained in discarded products. Japan possesses large reserves of these resources. In attempting to realize effective utilization of Japan’s urban mines, the efforts of RtoS Research Committee, which was established in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University in March 2006, and others have been based largely on social systems and economic problems. Dr. Harada’s "artificial ore recycling" is considered to show the possibility of solving one technical problem.
- To date, "artificial ore recycling," or to coin an expression, "urban concentrates," has been understood exclusively in terms of "recovery" "extraction." Conventionally, the focus of attention has tended to be on added value in the extraction process. However, the aim of urban concentrates is to supply recycled resources which are more easily extracted, and thus have higher added value, by applying technology in the intermediate stage, that is, by actively introducing a process of "enrichment" in the recycling process. In the mining of natural ores, low purity “crude ore” is normally processed to a higher concentration at the mine head. This product is called "concentrates." The above-mentioned concept of urban concentrates focuses on a process corresponding to the production of enriched "concentrates," which had been lacking in conventional recycling of urban mines.
- In urban concentrates, the valuable metals contained in discarded products are not extracted directly. Rather, the concentration of the object valuable metal, such as gold, rare metals, etc. is first increased by reducing the contents of other admixed materials which would hinder extraction and refining, and the resulting product (corresponding to the concentrates in conventional mining) is used as raw material in the downstream extraction and refining processes. This greatly reduces the load on refining furnaces and other equipment in the extraction and refining processes, and thus can lowers one technical barrier to recycling.
- The technology which is the key to urban concentrates is "enrichment." For this, sorting technologies which focus on the properties of the metal components are necessary. These technologies may be a combination of decomposition, pulverizing, and the like. Examples include a selective crushing and fine particle separation technologies developed by AIST, and the pinpoint separation technology developed by NIMS. Considering long-term efficiency, it is also important to grapple with design-for-disassembly materials in the products themselves. In this connection, dismantlable joining and other technologies being researched at NIMS are expected to make an important contribution.
- In addition to the above-mentioned presentation at the 2008 Spring Meeting of the MMIJ, a related presentation on the "Development of a Materials Strategy Model Considering Resources and the Environment" was made in a symposium at the 2008 Spring Meeting of the Iron and Steel Institute of Japan to be held at Musashi Institute of Technology March 26-28.
Fig.Current flow focusing on gold in cell phones
