NKK's Waste Gasifying and Direct Melting Furnace Certified
NKK's waste gasifying and direct melting test plant at its Tsurumi Works
A high-temperature gasifying and direct melting furnace for wastes developed by NKK has recently passed a technical evaluation and was certified by the Waste Materials Research Foundation, an organization affiliated with the Health and Welfare Ministry. With the certificate, the facility has become eligible for governmental subsidies, and NKK expects that orders will increase from local municipalities. In NKK's gasifying and direct melting furnace,municipal and industrial wastes such as shredder dust are gasified at temperatures above 1,000°C and melted in one step, resulting in a reduction in waste volume and recovery of high-quality recyclable slag. Since the technology helps lessen the burden on permanent disposal sites, it has been attracting considerable attention. NKK's gasifying and direct melting furnace is based on a combination of the company's blast-furnace ironmaking technology and its fluidized-bed technology that has proven effective as a waste disposal process. Because the waste is melted in a high-temperature reducing atmosphere in the shaft furnace, the upper part of which is kept in a fluid state, it is possible to reduce emission of dioxin in flu gas to less than 0.1 ng-TEQ/Nm3 and prevent the elusion of heavy metals from the recovered slag. After many years of R&D and bench tests, in December 1995 NKK constructed a demonstration test plant with a daily processing capacity of 24tons at its Tsurumi Works. The plant was test operated seven times by melting seasonally varying municipal and industrial wastes to verify its per-formance. NKK collected data from these tests,which were summarized in a technical evaluation application and submitted to the Waste Material Research Foundation in December 1997. |
