A conductivity probe for thickeners : calibration and level estimation

Vergouw, Ir. Jolanda.; Vergouw, Ir. Jolanda.

Thesis

A conductivity probe for thickeners : calibration and level estimation

Public Deposited

Analytics

Download PDF

Creator

Vergouw, Ir. Jolanda.

Contributors

Finch, J. A. (advisor)

Abstract

English

Thickening is the separation of suspended solid particles from a liquid by gravity settling. As a feed stream enters the thickener, the solids settle to the bottom. Clarified liquid overflows the top and the settled solids (underflow) is removed. Thickeners are widely used in the minerals and metal processing industry. To assist in the monitoring and control of thickeners a conductivity probe has been developed. Test work was carried out on a concentrate thickener at the Copper Cliff, Ontario Division of Inco Limited in Sudbury. The conductivity probe is a multicell arrangement. It exploits the difference in conductivity between liquid, slurry and settled solids. A conductivity profile is collected which locates the interfaces (liquid/slurry, slurry/settled solids) by detecting the change in conductivity, The conductivity profile can be readily converted to a solids concentration profile using a model due to Maxwell. From the solids profile, a solids inventory are obtained along with an estimation of underflow density. The main tasks in this thesis were to (a) develop a method of on-line calibration and (b) develop a level estimation procedure. The former was achieved by designing a portable probe and lowering it in to predetermined positions corresponding to rings on the probe. The time between re-calibration was also established (ca. 10 days). In the case of the level a previous method using a 0--1 scale has been converted to a true bed height using the bed height estimated by the operators using a weighted rope.

Last modified