Oil sands slurry and waste recycling mechanics in a flexible pipeline system

Abstract

Slurry transportation is an economic haulage system in oil sands and coal mining operations characterized by long haulage distances and rugged terrain. In such conditions, the ton–km–h limits for truck haulage are exceeded creating extreme tire wear and high maintenance costs. Steep haul grades and rugged terrain also cause mechanical wear and tear, which decrease haulage equipment economic life. In addition, waste materials may have to be recycled from the plant to the tailings dam or to the mined out areas as a backfill. The destination of these waste materials may require flexible pipelines for access and efficient recycling process. Hydraulic transportation is a proven and viable technology for slurry transportation in such conditions. Currently, stationary pipeline transportation is being used in transporting minerals in many mines. There is an increasing demand to create slurrified minerals at the mining faces to be transported to the processing plant and the subsequent recycling of the waste from plant to the tailings dam and mined out areas. However, stationary pipelines are not capable for dealing with the rapidly changing configuration of the mining faces and topography. In this paper, the authors present a conceptual design for the ground articulating pipeline (GAP) technology to address this problem. The GAP system consists of pipelines connected together with flexible joints in each pipe section, which allows deflection to avoid torsional stresses from the adjoining frames. This flexible arrangement accommodates the horizontal and vertical displacements of the mobile system as it follows the hydraulic shovels in the excavation process. The mechanics of the GAP system, as well as the production-economic function, are formulated and simulated over an extended period using data and information from Syncrude's North Mine. The results show that the GAP system is technically and economically viable for productivity between 6300 and 6500 tons/h. The simulated head loss for the GAP system is 15.66 m per 400 m, which compares with 20 m per 400 m for the existing stationary system at Syncrude. The pressure gradient–radius curves are asymptotic to the pipe boundaries, which indicates steep axial pressure gradient in these areas.