Abstract
In recent years, heat treatment has attracted attention as a means to improve the color sorting technology with the aim of improving the quality of low-grade limestone. The crucial stage in this technique is to evaluate the breakage characteristics of the sample materials after color sorting. In this study, the breakage characteristics of samples showing color differences after heat treatment and of the original raw material were investigated using a laboratory ball mill. The grinding was characterized using the population balance model. Specific rates of breakage and the primary breakage distribution were experimentally determined by first-order kinetic plots and the BII method. The breakage parameters were also back-calculated by employing a simplex method. Grinding of the three materials indicated first-order kinetics, and the experimental results were well described by the model with parameters obtained by back-calculating.
Highlights
Limestone has approximately 300 different reported uses and can be processed into a variety of products
Cement and steel industries account for a high percentage of this usage, and in Korea, the steel and cement industries are the largest consumers of limestone
The material that has the greatest influence on the quality of limestone is carboxylation reaction with lime (CaO), and the refining of low-grade limestone is becoming an important issue as high-grade limestone reserves are depleted
Summary
Limestone has approximately 300 different reported uses and can be processed into a variety of products. The dolomite crystals in limestone were calcined by heat treatment into CaO, and the difference in the grinding rates between the materials was analyzed to improve the limestone grade. These improvements can be maximized through optical separation based on material color differences after calcination. Mathematical modeling based on the mass balance equation and simulation of the grinding process using two functions—corresponding to the specific rate of breakage and primary breakage distribution—were performed. The particle size of the ground product can be calculated at certain grinding times, and the production rate and particle size distribution can be predicted for the grinding/classification circuit
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