Axial flow reversal and its significance in air-sparged hydrocyclone (ASH) flotation
- Univ. of Utah, Salt Lake City, UT (United States). Dept. of Metallurgical Engineering
In recent years the potential of air-sparged hydrocyclone (ASH) flotation for fine coal cleaning has been demonstrated both in pilot plant testing and in a plant-site demonstration program. Further improvements in the ASH technology will depend, to some extent, on improved understanding of the complex multiphase fluid flow. Froth transport plays a very important role in determining the efficiency of fine coal cleaning by ASH flotation. It should be noted that the surface of zero axial velocity is of particular significance in froth transport because the location of this surface actually accounts for the amount of froth being transported to the overflow. In this regard, the axial flow reversal has been examined based on specially designed tracer experiments. On the basis of these experimental results, modeling efforts were made to characterize the flow pattern in the ASH. The theoretical predictions based on turbulent fluid dynamic considerations were found to describe experimental observations regarding the surface of zero axial velocity. These results that define the surface of zero axial velocity together with froth phase features established from X-ray CT measurements provide an excellent description of the flow characteristics in ASH flotation and explain the effect of various process variables, such as dimensionless area (A*), dimensionless flowrate (Q*), inlet pressure, percent solids, etc., on flotation recovery. On this basis it is expected that further advances in the design and operation of the ASH system can be made, leading to more efficient use of the ASH technology for fine coal cleaning.
- DOE Contract Number:
- FG22-90PC90311
- OSTI ID:
- 257054
- Report Number(s):
- CONF-950952-; TRN: IM9631%%260
- Resource Relation:
- Conference: 12. annual international Pittsburgh coal conference, Pittsburgh, PA (United States), 11-15 Sep 1995; Other Information: PBD: 1995; Related Information: Is Part Of Twelfth annual international Pittsburgh coal conference: Proceedings. Coal -- Energy and the environment; PB: 1248 p.
- Country of Publication:
- United States
- Language:
- English
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