OXYFINES - A NEW TECHNOLOGY FOR DIRECT RECYCLING OF EAF DUST AND SLUDGE

摘要

There is considerable demand for increases in the recycling of dust and sludge within the metallurgical industry. The current solutions are few in number and not very competitive. For sludge, there is frequently no viable alternative at all. OXYFINES is an oxy-fuel based technology developed by Linde Gas for in-plant recycling. It provides fines, dust, sludge (without any drying stage) and other byproducts to be recycled directly back into existing processes or a separate unit on-site. The OXYFINES technology has successfully been applied to recycling of several dry and wet materials, including fines and dust from production of different ferroalloys, iron powder dust and rejects, carbon and stainless steel-making dust, dust and sludge from blast furnaces and steel-making converters. Additional materials, including e.g. pickling sludge and scarfing granulates, are now conceived for testing. As the recycled materials contain metals of different kinds, OXYFINES does not only provide a solution to the problems connected with dust and sludge generated in metal production. It also turns these materials into a low-cost raw material useful for the production in question, thus replacing a part of the raw material input. OXYFINES has successfully been applied to many materials. The recovery rate has been shown to be very high, and a recycling rate of 3.5 t/h has been proven. When applied in EAF steel-making it has no negative impact on the established operation practice. For direct recycling in an EAF with zinc-containing dust, a bleed-off will be required at a certain zinc level. For EAF mills OXYFINES must be considered as a viable method of internal recycling of dust and sludge, thus avoiding or minimizing external treatment and landfill dumping. Additionally, as OXYFINES provides a flexible system, it opens up additional opportunities within this area.