Slurry

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

A slurry is a thin sloppy mud or cement or, in extended use, any fluid mixture of a pulverized solid with a liquid (usually water), often used as a convenient way of handling solids in bulk.^[1] Slurries behave in some ways like thick fluids, flowing under gravity but are also capable of being pumped if not too thick.

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^[2][3]
• 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^[4]
• 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^[5]
• 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^[6]

Calculations

Determining solids fraction

To determine the percent solids (or solids fraction) of a slurry from the density of the slurry, solids and liquid^[7]

$\phi_{sl}=\frac{\rho_{s}(\rho_{sl} - \rho_{l})}{\rho_{sl}(\rho_{s} - \rho_{l})}$

where

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

$\rho_{s}$ is the solids density

$\rho_{sl}$ is the slurry density

$\rho_{l}$ is the liquid density

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

$\phi_{sl}=\frac{\rho_{s}(\rho_{sl} - 1)}{\rho_{sl}(\rho_{s} - 1)}$

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

$\phi_{sl}=\frac{M_{s}}{M_{sl}}$*100

therefore

$M_{sl}=\frac{M_{s}}{\phi_{sl}}$

and

$M_{s}+M_{l}=\frac{M_{s}}{\phi_{sl}}$

then

$M_{l}=\frac{M_{s}}{\phi_{sl}}-M_{s}$

and therefore

$M_{l}=\frac{1-\phi_{sl}}{\phi_{sl}}M_{s}$

where

$\phi_{sl}$ is the solids fraction of the slurry

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

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

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

Volumetric fraction from mass fraction

$\phi_{sl,m}=\frac{M_{s}}{M_{sl}}$

Equivalently

$\phi_{sl,v}=\frac{V_{s}}{V_{sl}}$

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

$\phi_{sl,v}=\frac{\frac{M_{s}}{SG_{s}}}{\frac{M_{s}}{SG_{s}}+\frac{M_{l}}{1}}$

So

$\phi_{sl,v}=\frac{M_{s}}{M_{s}+M_{l}SG_{s}}$

and

$\phi_{sl,v}=\frac{1}{1+\frac{M_{l}SG_{s}}{M_{s}}}$

Then combining with the first equation:

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

So

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

Then since

$\phi_{sl,m}=\frac{M_{s}}{M_{s}+M_{l}}=1-\frac{M_{l}}{M_{s}+M_{l}}$

we conclude that

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

where

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

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

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

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

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

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

See also

• Grout
• Slurry pipeline
• Slurry transport

References

1. Oxford English Dictionary 2nd ed.: Slurry
2. Shlumberger: Oilfield glossary
3. Rheonova : Measuring rheological propertis of settling slurries
4. Portland Cement Association: Controlled Low-Strength Material
5. Red Valve Company: Coal Slurry Pipeline
6. Rheonova : Measuring food bolus properties
7. 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.