Experimental Investigation on the Multistage Particle Classification in a Zigzag Air Classifier
—In most industrial solid processing operations, the separation of particles is important and designed based on the terminal settling velocity as the chief operating parameter. This settling velocity is dependent on characteristic particle properties like size, density, and shape. In this work, multi-stage separation experiments of sand and gravel have been performed using different channel velocities and mass loadings of the air. The performance has been analyzed and discussed with respect to the separation functions, and characteristic parameters as separation sharpness and product quality. Furthermore, the SMART analysis is used to evaluate different parameter configurations.
Gravity Separation of Particulate Solids in Turbulent Fluid Flow
The separation characteristics of particles’ settling velocity, size, density, and shape are introduced, and the equivalent settling condition for laminar, transition, and turbulent flow are explained. A similarity model of particle transport in a turbulent flow field is briefly discussed. Typical operation principles in separation devices for counter current and cross-flow separation are presented. The separation function, cut point, sharpness, and separation stage utilization coefficient are determined to assess the efficiency for process sequences for multistage turbulent cross-flow separation. Satisfactory to very good results were achieved in the difficult separation of a partially liberated aggregate consisting of hardened cement paste rubble with sharpness from 0.66 to 0.94 at separation stage utilization coefficients of 7 to 87%. Specific mass flow rates of 3 to 16 t/(m2 · h) and mass related energy consumption of 0.2 to 8 kWh/t were obtained.
Photoinduced spin-state transition of Co3+ in the layered perovskite manganite thin film
The photoinduced effect, at different temperatures, on layered perovskite manganite La1.2Sr1.8Mn1.8Co0.2O7 thin film deposited on a SrTiO3(100) substrate has been studied using a He–Ne laser (632.8 nm) with the power of output 25 mW at low temperatures. The electrical transport and magnetic properties of the film are investigated systematically in the temperature region from 20 to 300 K. The resistance shows a significant decrease at low temperatures (T<90 K) under laser irradiation, which can be interpreted in terms of the spin-state transition of Co3+ ions. The magnetic field combined with the laser is also used to detect the photoinduced effect of the spin-glass state. The time dependence of the metastable system under several applied fields was also discussed. The system has the ability to keep a persistent memory of the magnetic history imprinted in its zero-field resistance.