Paste &Thickened Tailings

Thickening mining waste streams into higher solids concentration slurries and pastes is a widespread practice which has become the dewatering process of choice for a large number of mines globally. Thickening offers significant water recovery and process control when compared to traditional tailings dams, and the emergence of numerous thickener vendors has ensured that the technology is continually developing and improving. RCS offers independent and experienced services in this area, from flocculant selection and screening to rheological analysis of thickener underflow streams to determine rake torque and pumping requirements.

Flocculant screening

  • Analysis of free settling rate and maximum achievable solids concentration
  • Supernatant turbidity measurements for thickeners and clarifiers
  • Measurement of yield stress of unsheared sediment in order to provide qualitative indications of raking requirements
  • Measurement of yield stress profiles of fully sheared flocculated tailings over a range of solids concentrations in order to provide insight into solids concentrations achievable via thickening and effects of different flocculant types and dosage rates
  • Measurement of shear viscosity of flocculated non-Newtonian process streams and tailings at solids concentrations pertinent to operation, providing input data for pumping and transport requirements within operational window

Thickened Tailings Transport

  • Measurement of yield stress and viscosity of thickened tailings at a wide range of solids concentrations for input into pumping calculations
  • Particle size and specific gravity measurements
  • Mineralogical analysis of samples to provide a link between mineralogy and rheology and indicate the presence and abundance of clays
  • SEM imagery of samples to indicate shape/size/abundance of particles in samples
  • Analysis of thixotropic/shear effects on thickened tailings
  • Analysis of efficacy of thickener operation and optimisation of existing equipment in terms of throughput and underflow solids concentration

Data Analysis and Interpretation

  • Interpretation of experimental data to give viscosity curves over a wide range of pumping velocities
  • Prediction of dewatering behaviour for thickening devices based on experimental results
  • Assessment of potential for thickened tailings disposal and mine stope backfill

Site Visits

RCS has the capability of transporting mobile technical equipment to mining operations in order to undertake on site rheological and material characterisation testwork. Site visits are often preferable to laboratory test work as they allow for samples to be tested in their operational environment, minimising the effects of age and transportation on their behaviour and providing the most accurate data obtainable. Furthermore, site visits are useful in providing a detailed understanding of the process under investigation, which can lead to valuable insights into problem areas and assist in formulating optimal testwork matrices.

RCS can also work alongside thickener and filtration manufacturers during testwork campaigns and provide complementary, impartial data and analysis to our customers.