The hydraulic transport of high concentration stabilized flow full plant mineral tailings

This thesis involves an analytical and experimental investigation of the flow behaviour of high concentration stabilized mineral tailings used as backfill material. At high solids concentrations "anomalous" behaviour occurs and is indicated by diameter dependancy on rheogram curves. These curves are not coincident in the laminar flow region. The anomalous behaviour is examined by postulating the following mechanisms : 1. Slip velocity at the pipe wall 2. Wall effects due to particle interaction 3 . Boundary layer effects 4. Plug flow at high concentrations 5. Particle migration away from the wall leaving a sheared annular zone 6. Lateral dispersive stress acting between particle and pipe wall. The mechanism responsible for "anomalous" behaviour is found to be due to the presence of a dispersive stress acting on the pipe wall due to particle-particle and pipe wall contact. This only occurs above a critical solids concentration ratio which is defined in terms of the critical void ratio or freely settled particle concentration. The total wall shear stress is a combination of both the viscous shear stress and the solid shear stress due to the lateral dispersive stress. Measured data was obtained from several test facilities. in pipe diameters ranging from 13,48 mm to 101,5 mm and for solids volumetric concentrations from 25% to 55%. Measurements included mean mixture velocity, pressure gradient, in situ and delivered volumetric concentration, temperature and the solids particle size distribution. Vertical down pipeline pressure gradients were obtained for a 40 mm NB pipeline which was constructed for the research. A tube viscometer was used to obtain rheological parameters. The measured data was compared with several analytical models using the log standard error. Existing models were found to be unsuitable for these slurries. The "anomalous" behaviour of the high concentration stabilized slurries is explained. The flow behaviour of these slurries is analysed in detail. The output is in the form of a user friendly interactive pipeline design computer program.

Grantor dc:publisher.institution

Department of Civil Engineering

Year dc:date.issued

1991

Author dc:creator

• Paterson, Angus John Cawood

Advisor dc:contributor.advisor

• Lazarus, JH

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/5011

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/5011