Increasing efficiency of the regrind circuit of the Sarcheshmeh copper complex, S.M. Mousavi, Gh.A. Parsapour, S.D. Tafvizi, M. Mahmoudi, and S. Banisi

Generally, regrind circuits are used to increase the degree of liberation of value minerals which are fed to flotation circuits. At the regrind circuit of the Sarcheshmeh copper complex, four ball mills are in closed circuit with their hydrocyclone clusters. In the initial design of the plant, feed and underflow percent solids, and pressure drop of the hydrocyclones were 39% and 65%, and 15psi, respectively. Over the years, due to a reduction in the feed grade from 1.17% to 0.67% and changes in the operational conditions, the feed rate to each hydrocyclone cluster has decreased from 401 to 70t/h and consequently the pressure drop, feed and underflow percent solids have reduced to 4psi, 17% and 25%, respectively. The main objective of this research was to audit the feed solids concentration and pressure drop of the hydrocyclones and make the necessary modifications based on the Plitt’s model. The results of sampling showed that water recovery to underflow was 59% which was higher than normal values. By reducing the number of operating regrind mills from 4 to 2, the feed rate to each mill increased. After this modification and taking necessary measures in the plant to implement the new operating approach, the pressure drop, feed and underflow percent solids increased to 18psi, 28% and 58%, respectively. The water recovery of the hydrocyclones underflow decreased from 59% to 12%. These changes in addition to increasing the circuit efficiency saved 1000 kWh energy and decreased ball consumption by 925 ton/year because of reduction in the number of operating ball mills. Keywords: Regrind mills, flotation, audit, troubleshooting