NKK to Jointly Test Municipal Waste Plastics Recycling Technology

Thermal-decomposition dehydrochlorination and granulation test plant at NKK's Keihin Works

NKK, jointly with Shinagawa Fuel Co., Ltd., has begun demonstration tests using a newly constructed thermal-decomposition dehydrochlorination and granulation test plant, which is designed to remove polyvinyl chloride (PVC) from municipal waste plastics so that such plastics can be blown into a blast furnace as a reduction agent in ironmaking. The test facility, built adjacent to the No.2 blast furnace at NKK's Keihin Works, was put into full operation in March.

The test plant, with a processing capacity of 50kg per hour, employs a thermal decomposition device to remove hydrogen chloride from municipal waste plastics containing PVC, then cools and processes the molten plastic into granules. Plans call for conducting demonstration tests and a total process evaluation to be completed by August 1998 in preparation for constructing a commercially viable plant.

In October 1996, NKK commissioned the world's first integrated waste plastics recycling and blowing system for blast furnaces. The system installed at the Keihin Works No.1 blast furnace is steadily recycling industrial waste plastics collected from some 150 contracted companies in the Kanto region, achieving its full operational capacity of 30,000 tons per year at the end of March.

For the current demonstration tests, NKK joined hands with Shinagawa Fuel to develop a pretreatment test facility for reusing the waste plastics contained in municipal wastes. Unlike industrial wastes, in which waste materials are easily identified, municipal wastes contain all sorts of plastics, including PVC in concentrations of up to 10%. PVC, when broken down into hydrogen chloride, is a cause of corrosion problems in blast furnace facilities. It is therefore imperative to remove PVC from waste plastics prior to blowing them into the blast furnace.

The newly developed facility combines a thermal decomposition technology already in commercial use by Shinagawa Fuel to pre-treat waste plastics with NKK's waste plastic granulation technology that is applied after the PVC is removed.

In an effort to further promote waste plastic recycling technologies, NKK is also developing a PVC gravity separation system to process municipal waste plastics for use in blast furnaces. This research project has been undertaken jointly with the Japan Chemical Industry Association and the Japan Iron and Steel Federation under a contract from the New Energy and Industrial Development Organization (NEDO) and the Clean Japan Center.

In addition, in collaboration with the Japan PVC Environmental Affairs Council and the Plastic Waste Management Institute, this March NKK put into operation a new plant to remove chlorine, recover hydrochloric acid and reuse dehydrochlorinated plastics as a reduction agent in a blast furnace. This system is mainly designed for industrial PVC wastes, but if PVC is successfully separated from municipal waste plastics using the above technology, the recycling of PVC will advance another step.

Japan's Container and Packaging Recycling Law, which calls for the recycling of all plastics (other than PET bottles), is scheduled to take effect in April 2000. NKK is stepping up its R&D activities to broaden the scope of waste plastic recycling in blast furnaces to include not only industrial, but also municipal waste plastics.