Soft-Sensor Estimation of an Apatite Thickener Operation at the Siilinjärvi Concentrator

In slurry thickening, even and high slurry density is often a key requirement for successful operation of the subsequent process. In many cases, after a concentrate thickener, the slurry is fed to a filtration section. Therefore, disturbances in thickening can lead to increased filtration costs or even reduced plant throughput. Here, a Kalman filter based soft-sensor for an apatite concentrate thickener at the Siilinjärvi concentrator was set up. The aim is to monitor the thickener operation, especially changes in the solids mass in the thickener, and thereby to be able to reduce the number of process disturbance periods. Also, flow rate step experiments were carried out, indicating good operation of the estimator.