Tietjen unveiled its new online particle size controller, OPC, which measures the particle size of free-flowing bulk solids inline, providing continuous, user-defined control of the grist spectrum between 160 and 6000 μm.

The new approach ensures a consistent grist spectrum over time and across multiple batches or recipes. As a result, the quality of the grinding material is increased. Overall, less raw material is also lost, as deviations in the grinding quality are detected promptly and faulty batches are thus avoided or greatly reduced. For example, screen breaks are detected early, and the screens can be replaced.

The continuous monitoring of the grist spectrum also allows for the current wear of screens and hammers to be indirectly monitored. Maintenance can be carried out at the optimum time depending on the condition, which reduces costs due to rejects and at the same time saves the budget for maintenance parts.

Practically, the OPC is integrated into Tietjen's grinding module in a way that the ground material is transported to the OPC via a bypass. In the OPC itself, the particle size is recorded and evaluated with the help of the software. At the beginning of each measurement, the regrind spectrum to be achieved is defined in the OPC software. If the spectrum is outside the specification during the measurement, the operator is informed.

To achieve the highest possible degree of automation in production, the OPC is preferably used with the large chamber mill GDX and the air-gravity separator AGS AD. Screen changes on the large chamber mill GDX are automated, and the AGS AD automatically discharges foreign particles.

Tietjen will exhibit the OPC live at the EuroTier from November 15-18, 2022 in Hanover, Germany.