Polymer injection technology as foaming slag agent in the EAF: Operations in Australia and Thailand

The disposal of polymeric materials, such as waste plastics and tires, represents an environmental challenge worldwide. The recycling of waste tires in particular is problematic due to their non-biodegradable nature and low bulk density. In most advanced economies, the vast majority of end of life tires are illegal disposed of or sent to land fill. Storage of tires in land fill dumps creates potential fires and health hazards, as toxic pollutants are released in case of a fire. OneSteel, the Australian steel manufacturer, in co-operation with the University on New South Wales, has developed a method to utilize waste polymers, and recycled tires more specifically, as an alternative source of carbon in Electric Arc Furnaces (EAF) to improve slag foaming and hence furnace efficiency. OneSteel has been using this technology within its Sydney and Laverton EAFs for over four years and over 41,000 heats, consuming over one million tires in the process. The first commercial implementation of this technology was performed in May 2011 at UMC Metals, Thailand. In all three cases, benefits derived from the implementation of Polymer Injection Technology translated into cost and productivity benefits. Benefits include: reduction in the quantity of foaming agent injected, a reduction in raw material cost of the injectant, an increase in average active power, a reduction in power on time, and an improvement in yield.