Analysis of specific discharge rate functions in industrial scale cement grinding multi-compartment ball mills to assist ball mill modeling

• Multi-compartment ball mill model structures were proposed.
• Particle discharge rate functions were described.
• Particles follow different discharge rate patterns in dry multi-compartment ball mills as compared to SAG mills.

Specific discharge rates in industrial scale multi-compartment cement grinding ball mills were determined using industrial scale data to assist modeling of multi-compartment ball mills. Multi-compartment ball mill model structures were proposed to estimate normalized specific discharge rate functions. Multi-compartment mills were divided into perfectly mixed mill segments to describe material transport mechanism in the mill. Specific discharge rate functions were determined by using the estimated mill hold-up for perfectly mixed mill segments at the steady state condition of the cement grinding circuits. Estimated normalized discharge rate functions were found to be different than the basic pattern observed in semi-autogenous mills due to the differences in design and operational conditions of the mills. Coarse particle accumulation was found to have a significant effect on discharge rate function pattern. Estimated normalized discharge rate functions could be used in modeling of multi-compartment ball mills.

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