In the steelmaking-continuous casting (SCC) production process, machine breakdown is one of the most common disturbances which may make the current schedule unrealisable. Existing rescheduling models for machine breakdown only employ one constraint that charges cannot be processed on this machine in its failure period. However, this method is effective for steelmaking furnace breakdown and refining furnace breakdown but invalid for continuous caster breakdown. Due to the production characteristics of continuous caster, reallocating a casting order and a continuous caster for each unfinished charge on the broken down continuous caster is necessary before making a new schedule. Different reallocation strategies have different impacts on charge’s processing time and processing stage route in the dynamic scheduling process. Therefore, SCC dynamic scheduling for the continuous caster breakdown is different from the other machines. In this paper, the impacts of these strategies are studied, and a dynamic scheduling model which can be used to generate a new schedule for each strategy is built. To obtain a high-quality solution in acceptable computational time for this model with NP-hard feature, a hybrid algorithm featuring a genetic algorithm combined with a general variable neighbourhood search is developed based on the problem-specific characteristics. Computational experiments on practical production data show that the proposed rescheduling method is effective for SCC dynamic scheduling with continuous caster breakdown.

Kinetics of Brazilian iron ore fines reduction was investigated in a micro fluidized bed, a newly developed kinetics analyzer for gas-solid reactions, where the effects of external and internal diffusion were significantly reduced by modifying the operation conditions. The reducing gas was a mixture of CO and N2 and the temperature ranged from 973K to 1123K. The experimental data was analyzed with respect to the reduction mechanism of iron oxides, and the feasibility of the segment treatment on the experimental data was discussed. The kinetics parameters were determined by the iso-reduction degree method as well as models matching method, and compared with available data in the literature. Moreover, a reduction model for iron ore fines was hence established in terms of piecewise differential rate function, and the reduction stage FexO→Fe is considered as the most likely limit step during the reduction of iron ore fines