Slurry

File:High angle.jpg

A slurry composed of glass beads in silicone oil flowing down an inclined plane.

A slurry is, in general, a thick suspension of solids in a liquid.

Examples of slurries

Examples of slurries include:

• A mixture of water and cement to form concrete
• A mixture of water, gelling agent, and oxidizers used as an explosive
• A mixture of water and bentonite used to make slurry walls
• A mixture of wood pulp and water used to make paper
• A mixture of water and animal waste used as fertilizer
• Meat slurry, a food product
• An abrasive substance used in chemical-mechanical polishing, a semiconductor manufacturing process
• A mixture of ice crystals, water and freezing point depressant, called slurry ice
• A wet-process cement rawmix
• A mixture of water, ceramic powder and various additives (e.g., dispersant) used in the processing of ceramics.
• Bean slurry, a food product
• A mixture of water and a starch (normally corn starch) used in cooking to thicken liquids to make a Blancmange (pudding) or translucent sauce (gravy).

Slurry calculations

Determining solids fraction

To determine the percent solids (or solids fraction) of a slurry from the density of the slurry, solids and liquid

<math>\phi_{sl}=\frac{\rho_{s}(\rho_{sl} - \rho_{l})}{\rho_{sl}(\rho_{s} - \rho_{l})}</math>

where

<math>\phi_{sl}</math> is the solids fraction of the slurry

<math>\rho_{s}</math> is the solids density

<math>\rho_{sl}</math> is the slurry density

<math>\rho_{l}</math> is the liquid density

In aqueous slurries, as is common in mineral processing, the specific gravity of the species is typically used, and since <math>SG_{water}</math> is taken to be 1, this relation is typically written:

<math>\phi_{sl}=\frac{\rho_{s}(\rho_{sl} - 1)}{\rho_{sl}(\rho_{s} - 1)}</math>

even though specific gravity with units tons/m^3 is used instead of the SI density unit, kg/m^3.

Liquid mass from mass fraction of solids

To determine the mass of liquid in a sample given the mass of solids and the mass fraction: By definition

<math>\phi_{sl}=\frac{M_{s}}{M_{sl}}</math>*100

therefore

<math>M_{sl}=\frac{M_{s}}{\phi_{sl}}</math>

and

<math>M_{s}+M_{l}=\frac{M_{s}}{\phi_{sl}}</math>

then

<math>M_{l}=\frac{M_{s}}{\phi_{sl}}-M_{s}</math>

and therefore

<math>M_{l}=\frac{1-\phi_{sl}}{\phi_{sl}}M_{s}</math>

where

<math>\phi_{sl}</math> is the solids fraction of the slurry

<math>M_{s}</math> is the mass or mass flow of solids in the sample or stream

<math>M_{sl}</math> is the mass or mass flow of slurry in the sample or stream

<math>M_{l}</math> is the mass or mass flow of liquid in the sample or stream

Volumetric fraction from mass fraction

<math>\phi_{sl,m}=\frac{M_{s}}{M_{sl}}</math>

Equivalently

<math>\phi_{sl,v}=\frac{V_{s}}{V_{sl}}</math>

and in a minerals processing context where the specific gravity of the liquid (water) is taken to be one:

<math>\phi_{sl,v}=\frac{\frac{M_{s}}{SG_{s}}}{\frac{M_{s}}{SG_{s}}+\frac{M_{l}}{1}}</math>

So

<math>\phi_{sl,v}=\frac{M_{s}}{M_{s}+M_{l}SG_{s}}</math>

and

<math>\phi_{sl,v}=\frac{1}{1+\frac{M_{l}SG_{s}}{M_{s}}}</math>

Then combining with the first equation:

<math>\phi_{sl,v}=\frac{1}{1+\frac{M_{l}SG_{s}}{\phi_{sl,m}M_{s}}\frac{M_{s}}{M_{s}+M_{l}}}</math>

So

<math>\phi_{sl,v}=\frac{1}{1+\frac{SG_{s}}{\phi_{sl,m}}\frac{M_{l}}{M_{s}+M_{l}}}</math>

Then since

<math>\phi_{sl,m}=\frac{M_{s}}{M_{s}+M_{l}}=1-\frac{M_{l}}{M_{s}+M_{l}}</math>

we conclude that

<math>\phi_{sl,v}=\frac{1}{1+SG_{s}(\frac{1}{\phi_{sl,m}}-1)}</math>

where

<math>\phi_{sl,v}</math> is the solids fraction of the slurry on a volumetric basis

<math>\phi_{sl,m}</math> is the solids fraction of the slurry on a mass basis

<math>M_{s}</math> is the mass or mass flow of solids in the sample or stream

<math>M_{sl}</math> is the mass or mass flow of slurry in the sample or stream

<math>M_{l}</math> is the mass or mass flow of liquid in the sample or stream

<math>SG_{s}</math> is the bulk specific gravity of the solids

See also

• Coal slurry impoundment
• Slurry pipeline
• Slurry Transport

References

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