Stewart Bodtker is a Project Engineer with Paterson and Cooke Canada Inc, Calgary, Alberta. Stewart Bodtker discusses the challenges in non-segregating tailings pipeline systems. He explains the flow properties of non-segregated tailings in turbulent and laminar flow in pipelines and the unique issues that need to be addressed.
Bodtker discusses yield stress in the tailings and the velocities required to move the product in turbulent flow or laminar flow. In the laminar pipeline flow, coarse particles separate from the rest of the tailings mixture. There is the un-sheared zone, the sheared zone and the coarse particle rich area which settles at the bottom of the pipe. The un-sheared zone above the coarse flow moves slower than the rest of the product, and it is not known what the friction losses are. In turbulent flow, more power is needed to move the tailings mixture and there is a higher rate of wear on the pipeline. Stewart Bodtker summarizes the choices for the pipeline designer, either turbulent or laminar flow. The former results in higher friction, higher power consumption and higher wear. Laminar flow results in lower wear, delivers on particle segregation but friction losses are unknown.
However, because the friction losses are not known for laminar flow, the choice is turbulent flow but Bodtker suggests, as close to the transition velocity as possible and to increase the yield stress so that there is segregating behaviour when the tailings reach the end of the pipe in the deposition area.
Stewart Bodtker recommends that collaboration between all relevant sectors -- geotechnical, hydraulics, process and operations - is necessary for the NST pipeline system to be successful in the deposition of tailings.
Stewart Bodtker's presentation was part of the Tailings and Mine Waste Conference, Banff, Alberta, November 3-6, 2013.
