Pulp Rheology

Testing Apparatus

Pocock Industrial utilizes different viscometers based on slurry properties or client needs. The Fann viscometer is used for measuring the rheological properties of solids containing slurries. The Haake viscometer is used for measuring the rheological properties of materials that can be used as paste back fill as well as brine solutions or other solutions with a high specific gravity or dissolved solids in solution.

Testing

Samples for rheological measurement can be produced from thickening tests. Our clients are also able to send us the sample they would like for rheological measurements to be completed on. Various solids concentrations are tested to aid in design of pumping and pipeline equipment.

Capabilities

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).