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A slurry is a mixture of solids with specific gravity greater than 1 suspended in liquid, usually water. Most common use of slurry is as a mean of transportation of solids being the liquid a carrier that is pumped on a device like a centrifugal pump. The size o solid particles may vary from 1 micron up to hundred of milliliters. The solids may settle at certain transport velocity and the mixture can behave as Newtonian or non-Newtonian fluid. Depending on the mixture the slurry may be abrasive and corrosive.

Examples

Examples of slurries include:

• Cement slurry, a mixture of cement, water, and assorted dry and liquid additives used in the petroleum and other industries
• Soil/cement slurry, also called Controlled Low-Strength Material (CLSM), flowable fill, controlled density fill, flowable mortar, plastic soil-cement, K-Krete, and other names
• A mixture of thickening agent, oxidizers, and water used to form a gel explosive
• A mixture of pyroclastic material, rocky debris, and water produced in a volcanic eruption and known as a lahar
• A mixture of bentonite and water used to make slurry walls
• Coal slurry, a mixture of coal waste and water, or crushed coal and water
• Slurry oil, the highest boiling fraction distilled from the effluent of an FCC unit in a oil refinery. It contains large amount of catalyst, in form of sediments hence the denomination of slurry.
• A mixture of wood pulp and water used to make paper
• Manure slurry, a mixture of animal waste, organic matter, and sometimes water often known simply as "slurry" in agricultural use, used as fertilizer after ageing in a slurry pit
• Meat slurry, a mixture of finely ground meat and water, centrifugally dewatered and used as food
• An abrasive substance used in chemical-mechanical polishing
• Slurry ice, a mixture of ice crystals, freezing point depressant, and water
• A mixture of raw materials and water involved in the rawmill manufacture of Portland cement
• A mixture of minerals, water, and additives used in the manufacture of ceramics
• A bolus of chewed food mixed with saliva
• A mixture of epoxy glue and glass microspheres used as a filler compound around core materials in sandwich-structured composite airframes.

Calculations

Determining solids fraction

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

${\displaystyle \phi _{sl}={\frac {\rho _{s}(\rho _{sl}-\rho _{l})}{\rho _{sl}(\rho _{s}-\rho _{l})}}}$

where

${\displaystyle \phi _{sl}}$ is the solids fraction of the slurry (state by mass)

${\displaystyle \rho _{s}}$ is the solids density

${\displaystyle \rho _{sl}}$ is the slurry density

${\displaystyle \rho _{l}}$ is the liquid density

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

${\displaystyle \phi _{sl}={\frac {\rho _{s}(\rho _{sl}-1)}{\rho _{sl}(\rho _{s}-1)}}}$

even though specific gravity with units tonnes/m^3 (t/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

${\displaystyle \phi _{sl}={\frac {M_{s}}{M_{sl}}}}$

therefore

${\displaystyle M_{sl}={\frac {M_{s}}{\phi _{sl}}}}$

and

${\displaystyle M_{s}+M_{l}={\frac {M_{s}}{\phi _{sl}}}}$

then

${\displaystyle M_{l}={\frac {M_{s}}{\phi _{sl}}}-M_{s}}$

and therefore

${\displaystyle M_{l}={\frac {1-\phi _{sl}}{\phi _{sl}}}M_{s}}$

where

${\displaystyle \phi _{sl}}$ is the solids fraction of the slurry

${\displaystyle M_{s}}$ is the mass or mass flow of solids in the sample or stream

${\displaystyle M_{sl}}$ is the mass or mass flow of slurry in the sample or stream

${\displaystyle M_{l}}$ is the mass or mass flow of liquid in the sample or stream

Volumetric fraction from mass fraction

${\displaystyle \phi _{sl,m}={\frac {M_{s}}{M_{sl}}}}$

Equivalently

${\displaystyle \phi _{sl,v}={\frac {V_{s}}{V_{sl}}}}$

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

${\displaystyle \phi _{sl,v}={\frac {\frac {M_{s}}{SG_{s}}}{{\frac {M_{s}}{SG_{s}}}+{\frac {M_{l}}{1}}}}}$

So

${\displaystyle \phi _{sl,v}={\frac {M_{s}}{M_{s}+M_{l}SG_{s}}}}$

and

${\displaystyle \phi _{sl,v}={\frac {1}{1+{\frac {M_{l}SG_{s}}{M_{s}}}}}}$

Then combining with the first equation:

${\displaystyle \phi _{sl,v}={\frac {1}{1+{\frac {M_{l}SG_{s}}{\phi _{sl,m}M_{s}}}{\frac {M_{s}}{M_{s}+M_{l}}}}}}$

So

${\displaystyle \phi _{sl,v}={\frac {1}{1+{\frac {SG_{s}}{\phi _{sl,m}}}{\frac {M_{l}}{M_{s}+M_{l}}}}}}$

Then since

${\displaystyle \phi _{sl,m}={\frac {M_{s}}{M_{s}+M_{l}}}=1-{\frac {M_{l}}{M_{s}+M_{l}}}}$

we conclude that

${\displaystyle \phi _{sl,v}={\frac {1}{1+SG_{s}({\frac {1}{\phi _{sl,m}}}-1)}}}$

where

${\displaystyle \phi _{sl,v}}$ is the solids fraction of the slurry on a volumetric basis

${\displaystyle \phi _{sl,m}}$ is the solids fraction of the slurry on a mass basis

${\displaystyle M_{s}}$ is the mass or mass flow of solids in the sample or stream

${\displaystyle M_{sl}}$ is the mass or mass flow of slurry in the sample or stream

${\displaystyle M_{l}}$ is the mass or mass flow of liquid in the sample or stream komi

${\displaystyle SG_{s}}$ is the bulk specific gravity of the solids

See also

• Grout
• Slurry pipeline
• Slurry transport

References

1. Shlumberger: Oilfield glossary
2. Rheonova : Measuring rheological propertis of settling slurries
3. Portland Cement Association: Controlled Low-Strength Material
4. Red Valve Company: Coal Slurry Pipeline
5. Rheonova : Measuring food bolus properties Archived 2013-11-30 at archive.today
6. Wills, B.A. and Napier-Munn, T.J, Wills' Mineral Processing Technology: an introduction to the practical aspects of ore treatment and mineral recovery, ISBN 978-0-7506-4450-1, Seventh Edition (2006), Elsevier, Great Britain

External links

• Bonapace, A.C. A General Theory of the Hydraulic Transport of Solids in Full Suspension
• Ravelet, F., Bakir, F., Khelladi, S., Rey, R. (2012). Experimental study of hydraulic transport of large particles in horizontal pipes. Experimental thermal and fluid science.
• Ming, G., Ruixiang, L., Fusheng, N., Liqun, X. (2007). Hydraulic Transport of Coarse Gravel—A Laboratory Investigation Into Flow Resistance.

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