Barry a. wills, james a. finch frsc, fcim, p.eng., in wills' mineral processing technology (eighth edition), 7.5.2 circuit operation. grinding circuits are fed at a controlled rate from the stockpile or bins holding the crusher plant product. there may be a number of grinding circuits in parallel, each circuit taking a definite fraction of the feed. an example is the highland valley cu/mo.Each milling circuit is unique, and as such the goals and most optimal control strategy might differ for individual cases. process iq is an expert in implementing control systems for sag and ball milling circuits, making use of advanced stabilisation and optimisation strategies developed by.