Dry cooling as a way toward minimisation of water consumption in the steel industry: A case study for continuous steel casting

The steel industry represents a chain of technological processes, which consume a vast amount of energy and water, and produce a large quantity of emissions. A number of restrictions and regulations have therefore been recently imposed on the steel industry and involved processes aiming at the improvement of the use of resources, reduction of footprint in the natural environment as well as at the enhancement of overall efficiency of the steel production. In contrast to other research papers, the paper focuses on water use in a particular steelmaking process - continuous steel casting, which is used to cast more than 95% of the worldwide steel production. Approaches allowing the minimisation of water consumption are first identified and analysed. Spray cooling using once-through water and its substitution with dry cooling coupled with internally-cooled rollers by means of closed-loop water is computationally investigated. A 3D heat transfer and solidification model for continuous steel casting, which was validated with data from an actual steel plant, was used for this purpose. The results indicate that partial substitution of water spray cooling with dry cooling can provide a 48% lower once-through water use, which represents approximately a 1.5 m3/min reduction in water consumption. The annual potential for water savings at a steel plant operating three casters at 24/7 is about 2.4 Mm3. •Water conservation in continuous steel casting was investigated.•Water spray cooling (WSC) and water spray and dry cooling (WSDC) were analysed.•Water use in WSDC was 3.75× higher than in WSC but most water in WSDC was re-usable.•Consumption of once-through water in WSDC was 48% lower than in WSC.•Annual water saving at a steel plant with 3 casters is 2.4 Mm3 when using WSDC.