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Moisture of bulk material has a significant impact on energetic efficiency of dry grinding, resultant particle size distribution and particle shape, and conditions of powder transport. As a consequence, moisture needs to be measured or estimated (modelled) in many points. This research investigates mutual relations between material moisture and particle classification process in a grinding installation. The experimental setup involves an inertial-impingement classifier and cyclone being part of dry grinding circuit with electromagnetic mill and recycle of coarse particles. The tested granular material is copper ore of particle size 0–1.25 mm and relative moisture content 0.5–5%, fed to the installation at various rates. Higher moisture of input material is found to change the operation of the classifier. Computed correlation coefficients show increased content of fine particles in lower product of classification. Additionally, drying of lower and upper classification products with respect to moisture of input material is modelled. Straight line models with and without saturation are estimated with recursive least squares method accounting for measurement errors in both predictor and response variables. These simple models are intended for use in automatic control system of the grinding installation.

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Comminution of raw materials consumes great shares of energy and operating costs of production and processing plants. Savings may be achieved, e.g., by developing new grinding equipment, such as the electromagnetic mill with its dedicated grinding installation; and by applying efficient control algorithms to these elements. Good quality control relies on mathematical models, and testing of versatile control algorithms is much simplified if a plant simulation environment is available. Thus, in this research, measurements were collected at the grinding installation with electromagnetic mill. Then, a model was developed that characterised the flow of transport air in the inlet part of the installation. The model was also implemented in software to provide the pneumatic system simulator. Verification and validation tests were conducted. They confirmed the correct behaviour of the simulator and good compliance with the experimental data, for both steady-states and transients. The model is then suitable for design and parametrization of air flow control algorithms and for their testing in simulation.