Intensification of granular bulk material separation in a blocked fluidized bed

Abstract

The intensification of the separation process of bulk granular materials which may be achieved by developing separation systems based on new technological principles is discussed. In our opinion, such a system is a blocked fluidized bed (BFB) which is a two-phase aeromechanical system that may be adjusted for separating capacity - effective density intermediate between the densities of the components being separated. The studies of granular bulk material separation in a BFB were conducted by using an experimental setup. The intensification of the separation in this device is achieved by increasing the rotational speed of the working element. Therefore, it was necessary to determine how this affected the size of the separation corridor - the gap between the trajectories of the mixture components during separation. A mixture of wheat grain and soil clods and stones of equal size was used for testing. The research findings showed that this mixture was completely separated. It was found that the size of the separation corridor increased slightly with increasing rotational speed of the working element. When the working element with the BFB rotated at speeds ranging from 100 to 400 rpm, the operating corridor size varied from 4.5 to 10 mm. It was also found that this design and technological scheme on which the experimental setup was based allowed gaining a separation system with a stable airflow distribution across its surface which positively impacted the efficiency of the separation. The airflow velocity measurements were conducted using an electric anemometer in a static state (the BFB was not rotating). Based on these measurements, airflow velocity distribution diagrams were constructed across the annular surface of the horizontal BFB. The results showed that, in this case, the airflow velocity was distributed almost uniformly across the circular surface of the BFB.