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Slurry

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Revision as of 20:06, 14 July 2020 by Comfr (talk | contribs) (paragraph break)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff) Mixture of solids denser than water suspended in liquid, usually water For the settlement in the North West province of South Africa, see Slurry, North West.
A slurry composed of glass beads in silicone oil flowing down an inclined plane
Potato starch slurry

A slurry is a mixture of solids denser than water suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids, the liquid being a carrier that is pumped on a device such as a centrifugal pump. The size of solid particles may vary from 1 micron up to hundreds of millimeters.

The particles may settle below a certain transport velocity and the mixture can behave as a Newtonian or non-Newtonian fluid. Depending on the mixture, the slurry may be abrasive and/or 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

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

where

ϕ s l {\displaystyle \phi _{sl}} is the solids fraction of the slurry (state by mass)
ρ s {\displaystyle \rho _{s}} is the solids density
ρ s l {\displaystyle \rho _{sl}} is the slurry density
ρ l {\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 S G w a t e r {\displaystyle SG_{water}} is taken to be 1, this relation is typically written:

ϕ s l = ρ s ( ρ s l 1 ) ρ s l ( ρ s 1 ) {\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

ϕ s l = M s M s l {\displaystyle \phi _{sl}={\frac {M_{s}}{M_{sl}}}}

therefore

M s l = M s ϕ s l {\displaystyle M_{sl}={\frac {M_{s}}{\phi _{sl}}}}

and

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

then

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

and therefore

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

where

ϕ s l {\displaystyle \phi _{sl}} is the solids fraction of the slurry
M s {\displaystyle M_{s}} is the mass or mass flow of solids in the sample or stream
M s l {\displaystyle M_{sl}} is the mass or mass flow of slurry in the sample or stream
M l {\displaystyle M_{l}} is the mass or mass flow of liquid in the sample or stream

Volumetric fraction from mass fraction

ϕ s l , m = M s M s l {\displaystyle \phi _{sl,m}={\frac {M_{s}}{M_{sl}}}}

Equivalently

ϕ s l , v = V s V s l {\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:

ϕ s l , v = M s S G s M s S G s + M l 1 {\displaystyle \phi _{sl,v}={\frac {\frac {M_{s}}{SG_{s}}}{{\frac {M_{s}}{SG_{s}}}+{\frac {M_{l}}{1}}}}}

So

ϕ s l , v = M s M s + M l S G s {\displaystyle \phi _{sl,v}={\frac {M_{s}}{M_{s}+M_{l}SG_{s}}}}

and

ϕ s l , v = 1 1 + M l S G s M s {\displaystyle \phi _{sl,v}={\frac {1}{1+{\frac {M_{l}SG_{s}}{M_{s}}}}}}

Then combining with the first equation:

ϕ s l , v = 1 1 + M l S G s ϕ s l , m M s M s M s + M l {\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

ϕ s l , v = 1 1 + S G s ϕ s l , m M l M s + M l {\displaystyle \phi _{sl,v}={\frac {1}{1+{\frac {SG_{s}}{\phi _{sl,m}}}{\frac {M_{l}}{M_{s}+M_{l}}}}}}

Then since

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

we conclude that

ϕ s l , v = 1 1 + S G s ( 1 ϕ s l , m 1 ) {\displaystyle \phi _{sl,v}={\frac {1}{1+SG_{s}({\frac {1}{\phi _{sl,m}}}-1)}}}

where

ϕ s l , v {\displaystyle \phi _{sl,v}} is the solids fraction of the slurry on a volumetric basis
ϕ s l , m {\displaystyle \phi _{sl,m}} is the solids fraction of the slurry on a mass basis
M s {\displaystyle M_{s}} is the mass or mass flow of solids in the sample or stream
M s l {\displaystyle M_{sl}} is the mass or mass flow of slurry in the sample or stream
M l {\displaystyle M_{l}} is the mass or mass flow of liquid in the sample or stream
S G s {\displaystyle SG_{s}} is the bulk specific gravity of the solids

See also

References

  1. Shlumberger: Oilfield glossary
  2. Rheonova : Measuring rheological propertis of settling slurries
  3. Portland Cement Association: Controlled Low-Strength Material
  4. http://www.iring.ca/_Knowledgebase/module_2_3.html?ms=AAA%3D&st=MA%3D%3D&sct=MjI%3D&mw=MjQw#
  5. Red Valve Company: Coal Slurry Pipeline
  6. Rheonova : Measuring food bolus properties Archived 2013-11-30 at archive.today
  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

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