Measuring the Percent Solids of a Slurry with the AccuPyc 1330 Pycnometer

Application Note Number 77

Measuring the Percent Solids of a Slurry with the AccuPyc 1330 Pycnometer

The percent solids of a slurry can be calculated readily and easily from analyses performed with the AccuPyc 1330 Pycnometer. To ensure accuracy, all pores of the solid must fill with liquid. Analyses were performed on samples of varying percentages of solids using the following procedure.

1. An instrument calibration was performed.
2. As an example, a weighed amount of clay and a weighed amount of water were placed in the sample cup of the AccuPyc 1330, then stirred thoroughly.
3. An analysis was performed on the sample prepared in step 2 using the following parameters, and the results were recorded.
   • Purges = 3
   • Runs = 3
   • Run Precision = No
4. Steps 2 through 3 were repeated seven times using different percentages of solids in the sample.
5. The density of the dry solid was measured.
6. The following equation was used to determine the percent solids of the slurry. Respective solid and liquid volumes and weights were all assumed to be additive in its derivation.

% solids (w/w) = 1-(Dliq/Dslu) x [Dsol/(Dsol-Dliq)] x 100

where (with all densities at the same temperature: 22 deg C)

Dliq = Density of liquid = 0.9977 g/cm3

Dsol = Density of solid = 2.6471 g/cm3

Dslu = Density of slurry (as measured by the AccuPyc1330)

% solids (w/w) = Weight percent solids

The results are shown in the following table.

Analysis Results

Analysis  Water     Clay    Dslu   % Solids Calc.  % Solids 
          Mass      Mass    1330   with a Known    Using 1330
           (g)      (g)   (g/cm3)  Water & Clay    Results
                                   Mass             (w/w)
                                     (w/w)          

  1      20.7313   2.1842   1.064       9.53        10.00
  2      20.7107   4.1794   1.117      16.79        17.14
  3      20.0836   6.0823   1.171      23.24        23.75
  4      51.2941  16.7724   1.174      24.64        24.10
  5      29.2592  11.9434   1.225      28.99        29.78
  6      40.1003  19.8484   1.241      33.11        31.46
  7      21.7233  12.9248   1.300      37.30        37.32
 

As shown in the table, the percent solids of a slurry can be determined reliably using AccuPyc 1330 density results. If you know the density of the solid and the density of the liquid, or measure them with the AccuPyc 1330, you can calculate the percent solids of a slurry using the equation shown above.