SGER: Environmentally Benign Iron Manufacture with Renewable Reductants

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0904459KawatraCurrent processes for manufacturing iron are highly non-sustainable, as they are dependent on fossil fuels to chemically reduce iron oxides to metallic iron. The iron and steel industry has long believed that only carbon produced from fossil fuels can be used in ironmaking, and so sustainable alternatives have not been pursued. The investigator has recently discovered that, contrary to the beliefs of the industry, it is not necessary to use carbon or other fossil fuels for iron production. Renewable biomass materials, particularly those that are rich in carbohydrates such as starches and cellulose, have been shown to be capable of reducing iron oxides to metallic iron. The objective of this project is to demonstrate the value of renewable reductants for ironmaking, and begin necessary fundamental studies that will determine chemistry and kinetics of the reactions between biomass components and iron oxides Intellectual Merit Recent developments in ironmaking furnace design have made it possible to use reductants other than metallurgical coke to manufacture liquid metallic iron. The industry does not yet appreciate the potential of renewable reductants such as biomass for this purpose. Industry personnel feel that the mechanisms of the reduction are not well understood, and that it has not yet been demonstrated that iron oxide reduction by biomass will proceed quickly or produce high-quality iron. The proposed project will carry out the necessary preliminary studies to demonstrate the potential of biomass technology, and to encourage industrial support for further fundamental research needed to convert the technology into an industrially-practical process. Broader Impact. Annually, 40 million tons of metallic iron are produced in the US from natural iron oxides. Its manufacture consumed an estimated 23 million tons of metallurgical coal in 2006. Since it is a fossil fuel, use of this coal contributes directly to a net increase in levels of atmospheric carbon dioxide. Replacing coal with biomass will reduce carbon emissions, as every ton of carbon dioxide released will be balanced by the growth of additional biomass as it is produced to feed the process. As a result, carbon will be in a closed loop in the ironmaking process, and there will be no net increase of carbon dioxide in the atmosphere. Biomass use will also be cleaner than coal, as it contains lower levels of mercury, sulfur, and other pollutants. It also contains lower levels of non-combustible ash-forming minerals, and therefore solid residues in the form of slag will be reduced in the biomass-based process.