Underwater camera can save 10% flocculants

Over-dosing is a common problem in thickener operation. It increases the operating cost, affects the downstream process and stresses the environment unnecessarily. A new tool has been developed by FLSmidth for real-time floc size monitoring and accurate reagent dosage control.

When flocculants are added to the slurry, particles agglomerate and the settling velocity increases accordingly, which leads to more efficient solid/liquid separation. Although larger floccules settle faster, they are however not always desirable and can sometimes inhibit thickener performance. To achieve the optimum floccules, the dosage rate has to be precisely balanced, and that requires sampling and settling tests. Such tests are not only time consuming, their results are very difficult to trust: "The slurry property and volume flow rate are changing so the characteristics at 10 am will have changed from the sample taken at 8 am – and slurry exhibit hysteresis so the act of sampling can itself alter the settling characteristics and affect the results," explains Technical Manager, Yihong Yang.

Now, an innovation from FLSmidth enables instant and accurate dosage adjustment: A small submersible camera is installed in the thickener feedwell to record floc images and analyze the floccule size in-situ and in real-time. Operators can use the floc images and size information to optimize the flocculant dosage on the spot.

The idea for the floc camera was ignited by the success of FLSmidth's E-DUC dilution technology; with the diluted slurry FLSmidth's R&D team was able to monitor the flocculation using a camera and developed a solution that could be combined with the E-DUC system to further improve thickener performance. The team tested the camera at customers and proved significant results.

The idea for the floc camera was ignited by the success of FLSmidth's E-DUC dilution technology; with the diluted slurry FLSmidth's R&D team was able to monitor the flocculation using a camera and developed a solution that could be combined with the E-DUC system to further improve thickener performance. The team tested the camera at customers and proved significant results.

“The floc camera system provides not only the floc size information but also other key characteristics, for example the structure. More importantly, the measurement is in-situ and real-time. With this device, up to 10% flocculants can be saved,” explains Yihong Yang. FLSmidth presented the Floc Camera at the SME conference in February in Denver.

Yihong Yang believes that the new tool will be widely adopted in the industry: “Our ultimate goal is to increase productivity in the operation by making dosage control 100% automatic."