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.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.
Trouble-shooting dual arch impressions.
Dual arch impression techniques enable the dentist to capture an impression of the prepared tooth, the opposing teeth and the occlusal registration in one procedure. This saves chair time and impression material.