Process Control In The Lornex Grinding Circuit

CIM Bulletin, Vol. 71, No. 793, 1978

James McManus, General Mill Superintendent, Allan R. Paul, Senior Electrical and Instrumentation Foreman, and Frank Yu, Senior Metallurgist, Lornex Mining Corporation Ltd., Logan Lake, B.C.

The original analogue instrumentation at Lornex Mining Corporation to optimize the throughput by controlling the power drawn by the semi-autogenous mills was found to be inadequate because of the frequent changes in ore type. Although the trunnion bearing pressure of the mill was a crucial control criterion, it was not utilized in the original control scheme. After several plant tests of different types of analogue controllers were unsuccessful in finding any control equipment suitable for this application, it was concluded that a digital process control computer was required. Computer control strategy to optimize the grinding rate by controlling the power and the bearing pressure of the semi-autogenous mill was developed and a Fox 2/30 computer made by Foxboro was selected. After six months of experimentation, it was found that the throughput was increased substantially by computer control.
Keywords: Metallurgy, Process control, Lornex, Grinding, Semi-autogenous grinding, Instrumentation, Automation, Computers, IMPAC, Supervisory programs.