Laboratory Services: Pulp Rheology (Viscosity Measurement)

Key Benefits

  • Determination of slurry sample viscosity at various conditions
  • Development of flow curve for slurry sample at various conditions 
  • Development of correlation between yield value vs. solids concentration for slurry sample at various conditions 
  • Characterization of slurry sample as Newtonian vs. non-Newtonian


Tests can performed to examine the rheological behavior of the thickened pulps across a specific shear rate range.  Data correlated include the relationship between apparent viscosity (Pa-sec) and shear rate (sec-1), and shear stress (N/m2) and shear rate (sec-1) at anticipated operating temperatures, grind size, solids concentrations, residual flocculant, and pH.

The apparent viscosity exhibited by a pulp at a specific shear rate can be due in part to grind size, solids concentration, mineralogical composition, temperature, flocculant dosage and concentration, and pH.

Correlations developed by Pocock Industrial are employed to characterize the various pulps under test as Newtonian or non-Newtonian.  Further, when the relationship between apparent viscosity and shear rate varies, the correlations characterize the fluid within a non-Newtonian class of fluids.

Viscosity Testing
As required by flow sheet demands for the sizing of agitators, pipe lines, pumps and screens, viscosity measurements will be made on Newtonian or non-Newtonian pulps.  Apparent Viscosity (Pascals-sec) will be determined at various Shear Rates (sec-1).  Samples will generally result from thickening tests, or pilot plant operations.

Data collected would allow for the following determinations:

1. Tests to determine apparent viscosity at known shear rates relative to solids concentration at known temperature and pH.

2. Data analysis to determine the yield value for the slurry at various solids concentrations.

3. Determination of the rheological classification of the pulp (ie. Newtonian vs. non Newtonian).


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