Prediction of Performance of an Industrial Poittemill in Production of Limestone Powders

Abstract

Experimental data were collected from tests using an industrial-scale high-pressure roller mill named the Poittemill grinding limestone materials for a range of parameters (such as force pressure, circumferential speed of roll, and feed size) in a Nordkalk AB plant located in Ignaberga, Sweden. These data were used to develop models of throughput, size reduction, and energy utilization with the parameters. A performance model with a correction coefficient, which has been developed, is able to describe the Poittemill throughput at various force pressures and circumferential speeds of rolls. The materials leaked beside the rolls are found to be empirically related to the circumferential speed of roll in a given force pressure. It is shown that two major parameters, force pressure and circumferential speed of roll, have an influence on the median size (d₅₀) of the ground product. Product fineness is decreased at a higher circumferential speed of roll or at a lower force pressure. The force pressure is the most dominant effect on energy utilization in the mill. The feed size used has a slight influence on the grinding results. Energy to the Poittemill for the comminution is utilized more efficiently at a lower force pressure or a higher circumferential speed of roll. Empirical models can predict the comminution characteristics with respect to the major parameters in the Poittemill system in dry mode. Product size-energy input relations have been also established, independent of the operating parameters used.

Keywords:

• HPRM
• limestone
• model
• powder
• roller

The author wishes to thank the MinBas and Swedish Mineral Processing Research Association (MinFo) for supporting this work. Thanks go to Ignaberga Plant, Nordkalk AB, Sweden, for providing the Poittemill system and the corresponding facilities. The author is also grateful to Mrs. Anneli Sköld, Mr. Roger Nilsonivs, and Mr. Bertil Persson in the Ignaberga plant for assistance in the experiments in this work.

Notes

C∗ = Q_T/(Q_m + Q_mL); C∗∗ = Q_T/(Q_c + Q_L).

All F-ratios are based on the residual mean square error.