Coal Ash Beneficiation and Utilization in Coal Separation Process
In recent years, coal production and consumption increased dramatically, especially in China. So, more and more attentions have been paid to coal preparation and coal ash utilization with the growing concern about the pollution by fly ash. The unburned carbon in fly ash significantly affects its utilization in many fields, especially in concrete production industry. Technologies such as flotation, triboelectrostatic separation and carbon burnout have been developed to remove carbon from coal ash. This paper introduces chemical compositions of a typical coal ash and a dry beneficiation method. For some kinds of fly ash, magnetically stabilized fluidized bed was studied to recover magnetic pearls from fly ash. The magnetic pearls are mainly composed of Fe3O2 and Fe3O4 and are mostly hollow spheres. The size distributions of three kinds of magnetic pearls are from 300 to 25 µm. A magnetic pearls fluidized bed and a magnetically stabilized magnetic pearls fluidized bed for coal dry separation are studied in the paper.
Magnetically stabilized fluidized beds for fine coal separation
Abstract Based on a prior study on air-fluidized dense media for 6–50-mm coal preparation, this paper presents results on magnetically stabilized fluidized bed (MSFB) on fine 1–6-mm coal preparation. Magnetic stabilization improves separation by lowering the lower size limit of separation and by preventing back mixing of the separated solids. This work addresses the fluidization media characteristics, the experimental system and separation results.
Study on magnetic fluidization of group C powders
Abstract The fluidization behavior of Geldart's group C powders has been studied and the experiments demonstrate that channels and bubbles can be eliminated effectively. Theoretical analysis shows that the fluidization quality is improved due to the formation of a chain structure. Two optical fiber probes are used to measure the size of the bubble in the bed and it shows that the bubble size decreases with increasing magnetic field intensity and magnetic powder fraction. The length of the chain, obtained by using a CA5300 board and modular system, has been found to be strongly influenced by the magnetic field intensity. A mathematical model has been derived through theoretical analysis and the calculated results are in agreement with experimental data. A dimensionless number M h is developed to forecast the magnetically condensed state.