The purpose of a mineral comminution circuit with a ball mill running in closed-loop with a hydrocyclone classification battery is to feed the downstream process with the target pulp particle size. Maintaining the optimal particle size in the flotation feed can significantly improve plant cash flow. In particular, reducing the amount of coarse material is often a major challenge. Existing instrumentation to provide on-line particle size measurement is considered standard equipment in most modern concentrator plants. However, its very low availability, in spite of high maintenance requirements, and its relatively slow update rate have made it difficult to use the information for real-time automatic control of the grind and classification circuit to achieve the target particle size for the flotation feed.