Flow Analysis Capability
eDart uses a Computational Fluid Dynamics packaged called FloEFD. FloEFD is embedded in SolidWorks and works directly on the solid model – no negative regions for the fluid need to be created. The finite volume mesh is fully controllable and uses a structured non-body fitted hex mesh. Where the cells intersect the solid boundary, what is termed partial cells are created, and a proprietary modified wall function is employed to deal with the boundary layer – both laminar and turbulent regimes may exist in the same model. Boundary conditions are applied, and iteratively, the computer converges upon a flow solution. eDart uses regular water for most of its analysis to flow patterns understanding. This is shown with velocity and pressure cut plots and flow trajectories, calculating relevant variables, modifying the presented results by using empirical functions to deal with factors such as aeration and solids concentration.
Design of Back Pressure Pipes
In a mineral concentrator, the crushed ore is passed through a cascading system of floatation machines. eDart valves are located between each cell to control the flow and are subjected to the pressure drop which is a function of the height between the two aerations in both, vertical head and density change should there be any feed introduced to the process. However, on the last cell, there is a significant pressure drop across the valve. Back pressure pipes, also known as goosenecks or riser pipes, are used in this case to represent another cell ensuring the valve need not be specially designed for the increased pressure drop. The resulting reduction in step for the last cell before the sump can be used to reduce the overall height of the bank or allow for another piece of equipment to be used as a metallurgical sampler. FloEFD is used to determine throat diameters and discharge height in these back-pressure pipes.
Design of distribution/splitter boxes
eDart uses FloEFD to model inlets and outlets of distribution and splitter boxes to optimise the design and get good mixing and even flow from the outlets. Good box design will often have a drop box in the inlet chamber to cushion the inlet flow if fed from the top, an underflow weir to the boiling chamber and an overflow weir which can be split easily to achieve the desired output.