OXYFINES Technique for Upgrading Zinc Containing Blast Furnace Sludge—Part 1: Pilot Trials

Abstract

In the Swedish steel industry, much work is put on further increasing the recycling and use of residual materials. However, blast furnace sludge is one residual which currently, despite its valuable contents of iron and carbon, is put on landfill or long-term storage due to its zinc content. Linde has developed the OXYFINES technique which is suitable for upgrading of fine particulate and zinc containing materials. The material is fed to the OXYFINES burner whereby its zinc content is vaporised to a generated dust phase whereas other non-gasifiable contents, such as iron, forms an oxidic sinter phase in the bottom of the reactor. The technique has proven a high degree of zinc separation, is relatively flexible and straightforward, and does not require sludge pre-treatment such as drying. Pilot set-up and trials, using the OXYFINES technique, were performed at Swerim’s research facility. In the trials, the effects from altering different process parameters were tested aiming to develop an optimal concept for upgrading the blast furnace sludge. The pilot trials’ results showed the required process settings to attain a high degree of zinc separation from the sludge, and to generate an iron oxide product, suitable for straightforward charging to the steelmaking process.

Keywords

• pilot trials
• OXYFINES technique
• zinc containing sludge
• residual upgrading