Innovative Binders for Efficient Recycling of Steel Mill Residues

Purpose and goal

In Innobind, increased knowledge has been gained about agglomeration and recirculation of steel mill residues with different binders and via various agglomeration methods. Partial replacement of cement could be done with the retention of cold strength and improved the reduction properties. Upgraded knowledge can be applied to other metallurgical industries and contribute in enhancement of residues re-circulation and saving of virgin materials.

Expected results and effects

Briquettes with reduced cement and 2% bitumen showed sufficient strength and good reduction properties for blast furnace. The briquettes have the potential to annually replace 15,000-45,000 ton of coke and reduce CO2 emission by 4,500-19,500 ton from Swedish blast furnaces. Mill scale briquettes with 2% sodium silicate or lime mixture briquettes with 0.5% Ca-stearate as binder achieved the desired quality for LD converter. Replacement of 5% of burnt lime with lime mix briquettes and 1.5% of scrap with mill scale briquettes can annually recycle 10,000 ton and 8,000 ton, respectively.

Planned approach and implementation

In this project steel mill residues and alternative binders are selected to meet the metallurgical requirements for BF and LD. Among different tested alternative binders, bitumen showed satisfactory mechanical strength for BF briquettes at replacement ratio of 2.0% of cement. Ca-stearate and sodium silicate showed superior mechanical strength of the briquettes from lime mix and mill scale, respectively. Pilot and full scale trials are recommended to investigate possible usage of developed briquettes and to evaluate its impact on recycling capacity and the process stability.