On the problem of control over the primary grinding mill ball charging

Abstract

Considering the fact that the costs related to grinding balls and electric power account for a significant share of operational costs incurred by concentrator plants, this paper highlights the relevance of using an optimized ball charge. The paper considers a conventional approach to ball charging, which involves doing calculations on the basis of a given throughput. The latter serves as a parameter for the specific ball consumption rate approval procedure. At the same time, no consideration is given for the ball wear rate as a parameter defining the grinding performance. It is noted that the ball charge dynamics can be analyzed based on the noise produced by the mill, or the vibroacoustic parameters of the mill. The paper examines some vibro-acoustic ball charge analysis techniques utilized by both domestic and international service providers. It is noted that in all these cases the technique uses just one physical parameter, which is not enough to monitor the total mill load. The VAZM-1M analyzer developed by Soyuztsvetmetavtomatika JSC analyzes and calculates an integral amplitude of the mill vibro-acoustic field. This ensures that all components of the grinding process are taken into account. The paper takes a detailed view of the findings obtained upon analysis of the primary grinding mill ball charge. The work was carried out at the Erdenet concentrator plant as part of contractual scope. A number of different ball charge options was considered, and is it noted that none of the options can resolve this problem completely. The authors describe a possibility to monitor the mill process load with the help of the VAZM-1M analyzer. The authors also analyzed the experiments that aimed at identifying the grinding parameters governed by the mill ball charge. It is shown that the VAZM-1M analyzer gives adequate readings of any ball charge deviations. The mill spectrum registered by the VAZM-1M analyzer contains a resonance peak, which is believed to correlate as a small mill ball charge spectrum. In this regard, a plan of further research was drafted that relies on the use of the VAZM-1M analyzer. The aim is to identify an exact frequency band that would adequately correlate with the mill ball charge.