Level and solids profile detection in thickeners using conductivity

CIM Bulletin, Vol. 87, No. 985, 1994

M. Xu, A. Probst and J.A. Finch, Department of Mining and Metallurgical Engineering, McGill University, Montreal, Quebec

Solids concentration (weight % solids) profiles and the clear liquid/slurry interface level (mud-line) were determined from conductivity measurements in thickeners at Falconbridge's Strathcona mill (Ni concentrate and non-mag thickeners) and Kidd Creek Division (Cu, Zn concentrates and final tails in the concentrator and a jarosite thickener in the Zn plant). The conductivity measurement system consisted of a probe 1.5 m in length with 23 electrode cells, a 24-channel relay, a conductivity meter and a computer. A conductivity profile is collected which locates the mud-line by a sharp change in conductivity. The conductivity measurements are readily converted to solids concentration profiles using a model due to Maxwell. The results from conductivity measurements were compared with direct measurements on local samples obtained using a modified Noranda sampler. It is concluded that the conductivity technique is applicable to locate the mud-line and to estimate the solids concentration profiles in thickeners. This on-line information could improve the operational efficiency of industrial thickeners.