Environmental Management
Pit Lakes
Numerical Modeling
Project Permitting

For mines operating in close proximity to coastal ocean waters submarine tailings placement may be a viable option for the disposal of waste rock. Where permitted, this involves mixing finely crushed rock with water to form a slurry that is subsequently delivered via pipeline to the ocean for sub-surface discharge.

Lorax is able to assess the environmental impact of submarine tailings placement by using a sediment transport and dispersion model in conjunction with either current measurements or the output from a numerical hydrodynamic model. In the case of current measurements, a specialized interpolation scheme is used to estimate the current at a location. Alternatively, a three-dimensional numerical hydrodynamic model is developed for a region and used to simulate currents under a variety of environmental conditions.

The sediment / tailings transport and dispersion model utilizes the following information to determine the behaviour of the tailings after discharge:

  • Particle size distribution, mass and density
  • Discharge location, depth and volume flux
  • Discharge pipe diameter

These data are used to calculate a settling velocity that varies with particle size. In saline ocean environments, the formation of flocs from fine-grained material must be taken into consideration as well.

The results from the model simulations provide information required for determining the concentration of suspended solids in the water column as well as the thickness of sediments deposited on the ocean bottom.