Conference article

To enable online estimation and further modeling of full scale airslide capacity, a small scale rig with adjustable length was built at POSTEC in Porsgrunn. Airslide capacity (alumina flow rates) for different lengths of 3 m, 7 m and 15 m and inclination of 0 to 3.1 degrees of airslide were measured by using pressurized air in the range of 3 to 6.5 barg. It became clear that interfaces (feeding silo and standpipe) also have a great influence on the capacity of an airslide. The standpipe should be integrated into the mechanical design of an airslide, because if the material cannot be delivered (discharged) properly from the feeding unit, there is no conveying. There is a strong analogy with the flow of Newtonian or non - Newtonian fluids in an open channel which can be applied to the flow of fluidized alumina in an airslide. In this paper, the hydrological model used by Agu and Lie [2014] has been used to model alumina flow in an airslide. From the general Saint-Venant model of the open surface, a mechanistic model for non- Newtonian flow of powder in a rectangular channel has been developed. Such theoretical models based on the mass and momentum balance with bottom friction along the powder bed are numerically challenging to solve. An ODE solver in MATLAB seemed promising and showed similar trends compared to the results obtained from a small scale rig. Results so far indicated that a more detailed analysis needs to be conducted in order to find out how to tune the model parameters to further improve the model fit.

Alumina transport; standpipe; fluidization; airslides; Saint Venant; non-Newtonian fluid