© Paterson & Cooke 2010 Page 1.1
1. Propiedades de Pulpas y su Clasificación Slurry Properties and Classification
Overview
• Slurry components
• Material properties
• Slurry terminology
• Basic process relations
• Slurry classification
Curso Transporte de Relaves Espesados y en Pasta 2010
• Slurry hydraulic behaviour
• Pipeline friction loss examples
Slurry Components
W t Water
Solids
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.2
Slurry Components
Typical types of solids
Curso Transporte de Relaves Espesados y en Pasta 2010
Tailings Concentrate Sand Slime
Material Properties
Particle size analysis• Different methods: sieving, elutriation, sedimentation and laser
• Produce different results – use a standard method to ensure consistencyconsistency
• Typical method: +75 μm sieving, -75 μm hydrometer
Finer than 5 μm Clay
5 μm to 74 μm (200 mesh) Silt
74 μm to 420 μm (35 mesh) Fine Sand
420 μm to 2 000 μm (9 mesh) Medium Sand
2 000 t 4 760 (4 h) C S d
Curso Transporte de Relaves Espesados y en Pasta 2010
2 000 μm to 4 760 μm (4 mesh) Coarse Sand
75 mm to 4 760 μm Gravel
© Paterson & Cooke 2010 Page 1.3
60 %
70 %
80 %
90 %
100 %
ge P
assi
ng
20 %
30 %
40 %
50 %
60 %
Cum
ulat
ive
Per
cent
ag
Curso Transporte de Relaves Espesados y en Pasta 2010
0 %
10 %
1 µm 10 µm 100 µm 1000 µm 10000 µm
Particle SizeTailings Kimberlite Sand
Material Properties
Particle packing concentration• Freely settled concentration represents the approximate transition
between low and high concentration slurries
Maximum packing concentration represents a concentration that is• Maximum packing concentration represents a concentration that is unachievable for slurry pipeline transport.
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.4
Material Properties
Particle micrographs
Platinum Tailings Kimberlite
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Heavy Mineral Concentrate
Slurry Terminology
Slurry• Mixture of solid particles and liquid.
• The liquid and solid phases do not react chemically.
Vehicle• Conveying medium, e.g. water or a mixture of water and fine
particles.
Homogeneous mixture• Non and slow settling slurries form mixtures that remain
homogeneous when quiescent for a period of more than an hour.
Curso Transporte de Relaves Espesados y en Pasta 2010
• The distribution of particles across the pipe section is uniform.
© Paterson & Cooke 2010 Page 1.5
Slurry Terminology
Heterogeneous mixture• The concentration of solid particles across the section of a horizontal
pipe is non-uniform.
For particles with a density greater than the vehicle density the• For particles with a density greater than the vehicle density, the concentration of solid particles increases towards the pipe invert.
Pseudo-homogeneous flow• Flow regime which behaves as single-phase homogeneous flow at
high mean mixture velocities, but becomes heterogeneous at lower mean mixture velocities.
• Pseudo-homogeneous flow can arise with virtually any slurry if the
Curso Transporte de Relaves Espesados y en Pasta 2010
g y y ytransport velocity is high enough to suspend particles reasonably uniformly by turbulence.
Mean mixture or bulk velocity• Flow rate divided by pipe cross-sectional area.
Slurry Terminology
Laminar flow• Flow behavior is dominated by the fluid viscosity.
• Particles of fluid move in straight streams with no mixing between adjacent streamsadjacent streams.
Turbulent flow• “The paths of individual particles are no longer everywhere straight
but are sinuous, intertwining and crossing each other in a disorderly manner so that thorough mixing of the fluid takes place” – Massey 1979
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.6
Slurry Terminology
Rheology• Viscous characteristics of a fluid or homogenous solid-liquid mixture.
• Note the term viscous indicates that laminar flow is being considered (where viscous forces dominate) as opposed to turbulent flow (where(where viscous forces dominate) as opposed to turbulent flow (where inertial forces dominate). Thus, rheology refers to laminar flow phenomenon only.
Rheogram or flow curve• A plot of shear stress versus shear rate for laminar flow conditions.
Curso Transporte de Relaves Espesados y en Pasta 2010
Slurry Terminology
Rheogram
200
220
Muestra 1
40
60
80
100
120
140
160
180
200
Ten
sió
n d
e co
rte
en l
a p
ared
, o
(Pa)
Cp=74,2%
Cp=74,1%
Cp=71,2%
Cp=69,5%
Cp=67,6%
Cp=65,0%
Cp=64,0%
Curso Transporte de Relaves Espesados y en Pasta 2010
0
20
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
Velocidad de Corte, (s-1)
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Concentration and Density Relations
Concentration• Volumetric concentration
• Mass concentration
Slurry Density
Curso Transporte de Relaves Espesados y en Pasta 2010
Mass and Volume Concentration
The volumetric concentration is the ratio of the volume of solids to the total volume of the mixture:
m
svC
The mass concentration is the ratio of the mass of solids to the total mass of the mixture:
M
Curso Transporte de Relaves Espesados y en Pasta 2010
m
sw M
MC
© Paterson & Cooke 2010 Page 1.8
Slurry DensityThe slurry density is the mass of slurry per unit volume:
mm
M
mm
Curso Transporte de Relaves Espesados y en Pasta 2010
Concentration and Density
Cv Cw ρm
wwm
Cv = 1 wsw
s
C
ws
wm
Cw = wsv
w
s
C
1
wsm
wms
Curso Transporte de Relaves Espesados y en Pasta 2010
ρm = wsvw C wsws
wswww C
C
1
© Paterson & Cooke 2010 Page 1.9
Concentration and Density
Consider a slurry at a mass concentration of 65%m.
The volumetric concentration is:• Copper tailings (ρs = 2.8 t/m3): Cv = 39.9%v
• Copper concentrate (ρs = 4.0 t/m3): Cv = 31.7%v
Curso Transporte de Relaves Espesados y en Pasta 2010
Slurry Classification
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.10
Main Slurry Classifications
Particle Settling Characteristics
Rheology
Solids Concentration
Curso Transporte de Relaves Espesados y en Pasta 2010
Particle Settling Characteristics
According to the particle settling, slurries may be classified into:
• Settling Slurries
• Non an slow settling slurries
• Mixed regime slurries
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.11
Particle Settling Characteristics
Mixed Regime
SettlingS
low
Set
tlin
gNonSettling
0 1 / 1 /
Curso Transporte de Relaves Espesados y en Pasta 2010
0.1 mm/s10 µm
1 mm/s32 µm
Non-Settling Slurries Slow Settling Slurries Settling Slurries
Vt ≤ 0.1 mm/s
(d = 10 µm for Ss = 2.65)
Brownian motion.
Homogeneous even in laminar flow
Vt ≤ 1 mm/s
(d = 32 µm for Ss = 2.65)
Turbulence
Particles settle in laminar flow.
Solid and liquid phases are separate. Liquid properties unaltered by the presence of the solids.
Turbulence and inter-particle collisions.
Concentration gradient in horizontal pipes
(uniform particle distribution).
Normally exhibit non-Newtonian behaviour at higher concentrations.
In a quiescent state, particles do not settle readily.
Frequently referred to as homogeneous slurries.
In a quiescent state, particles settle slowly en masse.
pipes.
In a quiescent state, particles settle readily.
Frequently termed heterogeneous slurries.
Curso Transporte de Relaves Espesados y en Pasta 2010
Mixed Regime Slurries
Contain a wide range of particle sizes and/or densities.
Fine particles mix with liquid to form a vehicle (Newtonian or non-Newtonian) with the coarser particles being transported inthe vehicle.
Most common slurry type encountered.
© Paterson & Cooke 2010 Page 1.12
Rheology
Newtonian Slurries• Linear relationship between shear stress and shear rate
She
ar S
tres
s
μ
Newtonian τ = μ γ
Laminar flow
Curso Transporte de Relaves Espesados y en Pasta 2010
• The rheogram passes through the origin and the slope of the flow curve is the mixture viscosity
Shear Rate
Rheology
Non-Newtonian Slurries• Has one or more of the following characteristics:
→non-linear rheogram
→the rheogram does not pass through the origin
→the rheogram varies with time (i.e. dependant on the shear history).
r S
tres
s
Non-Newtonian τ ≠ μ γ
Curso Transporte de Relaves Espesados y en Pasta 2010
Shear Rate
She
ar Non-Newtonian τ ≠ μ γ
(Next lecture by Angus)
© Paterson & Cooke 2010 Page 1.13
Solids Concentration
30%m 40%m30%m 40%m
Curso Transporte de Relaves Espesados y en Pasta 2010
Solids Concentration
Conventional slurries• The most common slurries in the industry
• Solids concentration under the Cbfree limit
Thickened Slurries• Obtained from high rate or high compression thickeners
• Solids concentration between Cbfree limit and concentration at Yield Stress of 100 Pa
Curso Transporte de Relaves Espesados y en Pasta 2010
Paste Slurries• Obtained from paste thickeners
• Solids concentrations at Yield Stress above 100 Pa
© Paterson & Cooke 2010 Page 1.14
High Concentration Slurries
High Concentration Non and Slow Settling Slurries High concentration settling slurries
Form paste mixtures.
Contain a high % of fine particle which form a non-
Form dense phase mixtures
Inter-particle contact is the dominant mechanismContain a high % of fine particle which form a non-Newtonian vehicle.
Vehicle yield stress dominates the flow behaviour.
Larger particles do not contribute significantly to the pipeline friction losses.
Generally operated in laminar flow due to
Inter-particle contact is the dominant mechanism supporting the particles.
There are insufficient fine particles to significantly alter the vehicle rheology.
Essentially a settling mixture in which settling is prevented by the high concentration of particles.
For concentrations greater than Cbfree, the pressure
Curso Transporte de Relaves Espesados y en Pasta 2010
Generally operated in laminar flow due to excessive amount of energy required to achieve turbulent flow.
Examples: high concentration tailings for surface disposal or underground backfill
o co ce a o s g ea e a Cbfree, e p essu egradients are very sensitive to small concentration changes.
Example: cyclone classified tailings backfill.
Paste and Thickened Tailings
High concentration mixed regime slurries
Non-Newtonian rheology• Typically characterized as a Bingham Plastic (discussed during next
lecture by Angus)
• May be time dependant
• Considered fully sheared condition for classification
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.15
Paste and Thickened Tailings
SlurryPa)
Paste
100
Slurry
Cake
Yie
ld S
tres
s (P
Thickened Tailings
Curso Transporte de Relaves Espesados y en Pasta 2010
Solids Concentration (%)
20
Paste and Thickened Tailings
69,7% - 10 Pa 72,6% - 30 Pa
74,4% - 100 Pa 76,3% - 300 Pa
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.16
Slurry Hydraulic Behaviour
Depending on the particle settlement characteristics, rheology and solids concentration, several models may be used to predict the slurry behaviour in transport and to calculate the hydraulic parameters in a slurryto calculate the hydraulic parameters in a slurry pipeline.
Thus, for each type of slurry, different design considerations should be applied related to:• Deposition and transition velocity
Curso Transporte de Relaves Espesados y en Pasta 2010
• Friction Head losses
• Pump derating
• Pipeline wear
Slurry Hydraulic Behaviour
Settling Slurries• Presentation 3 – Ray
Non-Newtonian Slurries – Pipe Flow• Presentation 4 - Angus
Paste and Thickened Tailings Transport• Presentation 5 - Rob
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.17
Pipeline Friction Loss Examples
70 %
80 %
90 %
100 %
ssin
g
20 %
30 %
40 %
50 %
60 %
Cum
ulat
ive
Per
cent
age
Pas
Curso Transporte de Relaves Espesados y en Pasta 2010
0 %
10 %
1 µm 10 µm 100 µm 1000 µm 10000 µm
Particle SizeMarine Sand HM conc HM Slimes
Marine Sand
Narrow size distribution• d50 = 422 μm
100 %
ρs = 2 600 kg/m3
Ss = 2.65
30 %
40 %
50 %
60 %
70 %
80 %
90 %
um
ula
tive
Pe
rce
nta
ge P
assi
ng
Curso Transporte de Relaves Espesados y en Pasta 2010
0 %
10 %
20 %
1 µm 10 µm 100 µm 1000 µm 10000 µm
Particle Size
Cu
Marine Sand HM conc HM Slimes
© Paterson & Cooke 2010 Page 1.18
Marine Sand
1.4
1.6
1.8
2.0
Pa/
m)
150 NB Pipe Loop
0 2
0.4
0.6
0.8
1.0
1.2
Pre
ssur
e G
radi
ent
(kP
Curso Transporte de Relaves Espesados y en Pasta 2010
0.0
0.2
0.00 1.00 2.00 3.00 4.00 5.00
Velocity (m/s)
Water 1.18 t/m3 1.27 t/m3 1.40 t/m3
Marine Sand
0.100
0.120
m p
ipe)
150 NB Pipe Loop
0.020
0.040
0.060
0.080
Hea
d Lo
ss (
m m
ixtu
re /m
Curso Transporte de Relaves Espesados y en Pasta 2010
0.000
0.00 1.00 2.00 3.00 4.00 5.00
Velocity (m/s)
Water 1.18 t/m3 1.27 t/m3 1.40 t/m3
© Paterson & Cooke 2010 Page 1.19
Heavy Mineral Concentrate
Narrow size distribution• d50 = 140 μm
90 %
100 %
ρs = 4 530 kg/m3
Ss = 4.53
30 %
40 %
50 %
60 %
70 %
80 %
Cu
mu
lativ
e P
erce
ntag
e P
assi
ng
Curso Transporte de Relaves Espesados y en Pasta 2010
0 %
10 %
20 %
1 µm 10 µm 100 µm 1000 µm 10000 µm
Particle Size
C
Marine Sand HM conc HM Slimes
Heavy Mineral Concentrate
1 4
1.6
1.8
2.0
a/m
)
150 NB Pipe Loop
0.4
0.6
0.8
1.0
1.2
1.4
Pre
ssur
e G
radi
ent (
kPa
Curso Transporte de Relaves Espesados y en Pasta 2010
0.0
0.2
0.00 1.00 2.00 3.00 4.00 5.00
Velocity (m/s)
Water 1.55 t/m3 1.72 t/m3 2.00 t/m3
© Paterson & Cooke 2010 Page 1.20
Heavy Mineral Concentrate
0 080
0.100
0.120
m p
ipe)
150 NB Pipe Loop
0.020
0.040
0.060
0.080H
ead
Loss
(m
mix
ture
/m
Curso Transporte de Relaves Espesados y en Pasta 2010
0.000
0.00 1.00 2.00 3.00 4.00 5.00
Velocity (m/s)
Water 1.55 t/m3 1.72 t/m3 2.00 t/m3
Heavy Mineral Slimes
Wide size distribution• d50 = 3.5 μm
90 %
100 %
ρs = 2 860 kg/m3
Ss = 2.86
30 %
40 %
50 %
60 %
70 %
80 %
Cum
ulat
ive
Per
cent
age
Pas
sing
Curso Transporte de Relaves Espesados y en Pasta 2010
0 %
10 %
20 %
1 µm 10 µm 100 µm 1000 µm 10000 µm
Particle Size
C
Marine Sand HM conc HM Slimes
© Paterson & Cooke 2010 Page 1.21
Heavy Mineral Slimes
Curso Transporte de Relaves Espesados y en Pasta 2010
Heavy Mineral Slimes
Curso Transporte de Relaves Espesados y en Pasta 2010
© Paterson & Cooke 2010 Page 1.22
Heavy Mineral Slimes
2.0
2.5
a/m
)
150 NB Pipe Loop
0.5
1.0
1.5
Pre
ssur
e G
radi
ent
(kP
a
Curso Transporte de Relaves Espesados y en Pasta 2010
0.0
0.00 1.00 2.00 3.00 4.00 5.00
Velocity (m/s)
Water 1.28 t/m3 1.31 t/m3 1.34 t/m3
Heavy Mineral Slimes
0 140
0.160
0.180
0.200
m p
ipe)
150 NB Pipe Loop
0 020
0.040
0.060
0.080
0.100
0.120
0.140
Hea
d Lo
ss (
m m
ixtu
re /m
Curso Transporte de Relaves Espesados y en Pasta 2010
0.000
0.020
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Velocity (m/s)
Water 1.28 t/m3 1.31 t/m3 1.34 t/m3
© Paterson & Cooke 2010 Page 1.23
Slurry Properties and Classification
Questions - Preguntas
Curso Transporte de Relaves Espesados y en Pasta 2010