Investigating Key Parameters Affecting Slurry Pipeline Erosion

• Author / Creator

  Sadighian, Ardalan

• Slurry pipelines are widely utilized in most mining operations to transport the raw materials and the tailings. These pipelines typically suffer from high wear rates. For example, in Canada’s oil sands industry, pipeline wear rates of 1 cm/yr are considered representative. To generate and measure such wear rates at the pilot-scale, significant resources (time and materials) are required; therefore, limited pilot-scale pipeloop investigations have been performed to study erosion in slurry pipelines. The present study is focused on identifying the underlying mechanisms affecting slurry pipeline erosion. The main goal is to relate the parameters affecting pipeline friction loss to erosion rate. Initially, a lab-scale slurry pot tester was chosen to investigate the effects of slurry properties on erosion rate. In this phase, the effects of carrier fluid viscosity, impact angle and particle properties on erosion rate were studied. It was observed that particle density and shape strongly affect the erosion rate. Slurry-specimen impact angle also significantly changes the erosion rate. Finally, specimen erosion rates were measured at various carrier fluid viscosities. It was observed that carrier fluid viscosity has an indirect effect on the erosion rate. Using Bagnold’s methodology, the normal and shear stresses on the specimen surface were calculated. The magnitude of the normal and shear stresses on the surface were identified as the key parameters affecting the erosion rate. In the next phase of the study, a purpose-built pipeloop was utilized to study the effect of slurry hydrodynamics on erosion rate using silica sand and Al2O3 slurries. Two pipe diameters (75 and 63 mm) were utilized in this study. It was observed that independent of particle type and pipe diameter, the erosion rate increases with increasing velocity. However, the erosion data from the two pipe diameters revealed that velocity cannot be used to model erosion data. After examining the evidence available in the literature, solids shear stress was introduced as an alternative to velocity for the purpose of erosion rate prediction. It was observed that the pipe erosion rate increases logarithmically with increasing solids shear stress. In general, specimen surface stresses were identified as the key parameter affecting the erosion rate. Using solids stresses, a new model was proposed to predict the effect of flow parameters on erosion rate. The model proposed is capable of predicting the effect of flow parameters such as solids concentration and carrier fluid viscosity on erosion rate, which represents an important new tool for scale-up purposes. The results of this study can directly be applied to predict erosion rates in slurry pipelines in the mining industry and specifically in Canada’s oil sands industry.

• Subjects / Keywords

  • Pipelines
  • Slurry
  • Erosion

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3GX45041

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.