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.

Due to depletion of resources and the spread of environmental pollution, the sustainability of raw materials is emerging as an important issue. Glass bottles are one of the products that are easy to recycle, and many studies have been conducted to improve the recycling rate. In this study, we attempted to develop the waste glass bottles process that can be recycled into a glass cullet and recycled glass aggregate. To produce a cullet from waste glass bottles(WGBs), color quality standards must be satisfied. Therefore, we applied a multistage color sorter to the experiment. The recycled aggregate glass must adjust the particle size. Thus, we experimented with the optimum crusher selection test when applying the crushing process. And, we confirmed the appropriateness of process by aspect ratio analysis of product. In addition, we confirmed the trends in the data required to set the optimum design and operating conditions of the selected vertical shaft impact(VSI) crusher using discrete element method(DEM) simulations.

This study investigates grinding media behavior and grinding efficiency in a laboratory-scale ball mill under different rotation speeds to identify energy-efficient operating conditions in ball mill grinding operations. Grinding efficiency is evaluated in terms of the effectiveness of energy transfer into particle breakage, as quantified by PBM-derived breakage-rate characteristics, rather than by conventional metrics based solely on energy consumption. Batch grinding tests were conducted at several fractions of the critical speed, and a Population Balance Model (PBM) was calibrated for each operating condition to quantify the corresponding breakage-rate characteristics. In parallel, Discrete Element Method (DEM) simulations were performed to analyze the motion of grinding media as a function of rotation speed. Media motion descriptors derived from DEM were integrated with the PBM-based breakage parameters to interpret efficiency trends. The results show that grinding efficiency does not increase monotonically with rotation speed; instead, an optimal operating region exists within the investigated range due to the balance between impact-dominated and surface-contact-dominated motion regimes. By linking DEM-quantified media behavior indicators with PBM-derived breakage-rate coefficients, the proposed integrated framework enables physics-based estimation of the optimal rotation speed region. This methodology provides a transferable basis for analyzing and improving grinding efficiency in ball mill grinding operations.