Abstract: An automatic control system is built for the high density slurry process for treating the acid sewage in Tongling Xinqiao Pyrite Mine by using PLC, inverter and Profibus, where Cohen-Coon algorithm is adopted for the control of the lime milk and flocculant dosage in the core link. The practice has proven that this control system has high reliability and excellent performance and is therefore worthy popularization.

Key words: S Sewage treatment, Automatic control, PLC, Inverter, Cohen-Coon algorithm