Classification and dewatering
of non-metallic minerals
Tailored calcium carbonate and kaolin treatment for industrial needs
In the production of non-metallic
minerals, classification and dewatering
are two process steps that can
significantly affect your profitability.
As drying is an energy-intensive step,
effective dewatering ensures fast
and more economical processing.
To further maximize the commercial
value of your end-product, accurate
control of the classification step
makes sure that you obtain the final
particle size and purity needed to
meet specific target application
requirements.
Using Alfa Laval decanter centrifuges
ensures continuous, operator-friendly
minerals dewatering with accurate
control in a fully enclosed process step,
which contributes to a better working
environment.
method involves mechanical processes
such as crushing, screening and washing,
followed by classification and dewatering.
The drier the product is after dewatering,
the more energy can be saved in the
final drying step of the calcining process.
Process overview
Product requirements can be very
specific, which creates a need for a suitable process for tailor-made production.
The final particle characteristics are
often critical for specific applications,
making it imperative to obtain a welldefined particle size distribution or
specific purity.
Calcium carbonate and kaolin, found in
quarries all over the world, are among
the most widely used minerals. After
a number of treatment steps they are
used not only as pigments in paint and
paper products, but also in ceramics
and cosmetics. The typical production
Crushing
Mining
Milling
Screening
and washing
Flotation
Classification
Calcium Carbonate ore
Ground Calcium Carbonate
(GCC) Production
Coarse product
Dewatering
Fine
product
MINING / BENEFICIATION
EXTRACTION & CONCENTRATION
MINING / BENEFICIATION
Product
Water
Solid-Liquid Separation
Leaching / Digestion
Screening /Washing
Pregnant Liquor
Pregnant Liquor
4
Surface Mining
EXTRACTION & CONCENTRATION
Solid-Liquid Separation
Fine GrindingLeaching / DigestionThickening
Precipitation
4
Crushing
Calcium carbonate
production
Precipitates /Concent
Tailings
MINING / BENEFICIATION
Flotation
2
Crushing
Precipitates /Concent
Precipitation
Screening /Washing
2
Surface Mining
Tailings
Flotation
Grind
Thickening
6
Thickening
Grind
Fines Rejects / Slimes
MINING / BENEFICIATION
Fines Rejects / Slimes
Limestone
CaCO3
Concentrate
Leaching
6
Concentrate
the
number of particles smaller than two
Solid-Liquid Se
Leaching / Digestion
microns.
This makes the classification
Tailings
Underground Mining
Screening /Washing
MINING / BENEFICIATION
step very important, as it can be the
Calcium carbonate is readily available
Surface Mining
The lime
Solid-Liquid Separation
/ Digestion
Coarse Reject
Tailings Pond / Dam
driving force behindLeaching
quality
differentiations
4
2
in quarries around the world. It is minedCoarse Reject
cycle
for
Tailings Pond / Dam
Screening /Washing
Tailings
Pond / Dam size and distribution.
based on
particle
as Surface
limestone
high-calcium
Miningand can be ground to
MINING / BENEFICIATION
Tailings Pond / Dam
4
The degritting
process before the
2 particle size. This produces
the right
lime
PURIFICATION AND METAL RECOVERYLeaching / Digestion
Solid-Liquid Separation Flo
Screening /Washing
classification
step is important if small
Surface Mining
Slaked
lime
Quicklime
PURIFICATION AND
METAL RECOVERY
GCC (Ground Calcium Carbonate)
viaCRUD
Pre
Crushing
Grind
Anode Slimes
2
amounts of sand are present.
Ca(OH)
CaO
2 Slimes
Anode
Flotation
a mechanical process in which the CRUD
Tailings
4
Fines Rejects / Slimes
Screening /Washing e d
Flotation
mineral is washed by aSurface
large
volume
Crushing
Grind
Mining
W ater ad d
Advantages
for all
Crushing
Grind
2
of water.
Fines Rejects / Slimes
3
ed
ed
1
3
Ca r bo nat
1
Tailings
at
He
Underground Mining
5
5
9
8
9
8
Solvent Extraction
Electrowinning
processes and requirementsConcentrate
Cathode
Tailings
Fines Rejects / Slimes
Concentrate
A decanter offers a Flotation
number of benefits,
3
Grind
regardless
of which calcium carbonate
Tailings
Tailings
production method is used or whether
Concentrate
3
orPond
dewatering
is required.
Coarse Reject classification
Tailings
/ Dam
Impurity Removal
Drying 5
Filtration
Decanter process
parameters
Tailings such
Impurity Removal
Drying
The
kaolin production
process has
Thickening
Coarse Reject
Tailings Pond / Dam
Filtration
Coarse Reject
Tailings Pond / Dam3
Thickening
pond level settings
strong
similarities with the
GCC process, as bowl speed,
Tailings Pond / Dam
Waste / Residue
and differential speed can be used to
5
as it includes both classification
and
Waste / Residue
Tailings
Coarse Reject
Tailings Pond / Dam
classify the product and particle sizes
dewatering steps
in which a decanter
Calcining PU
PURIFICATION AND METAL RECOVERY
deviating from a certain diameter can TailingsCalcining
centrifuge can be used.
Pond / Dam
Anode Slimesbe excluded. Anode Slimes
CRUD
CRUD
PURIFICATION AND METAL REC
Kaolin, one of the principal ingredients
Underground
Mining
PCC (Precipitated Calcium
Carbonate)
Crushing
1
is anotherConcentrate
calcium carbonate production of ceramic goods, is often called "china
Fines Rejects / Slimes
Underground Mining
clay".
Concentrate
Underground
Mining
3
method. The limestone
goes through
Solvent Extraction
1
1
the same primary mechanical crushing
Leaching
Leaching
process, but is then
heated
to
1000°C
in
Underground Mining
a calcination tower. 1
Electrowinning
Cathode
(Reduction, Precipitation,
Cementation, Crystallization)
(Reduction, Precipitation,
12
11
Cementation, Crystallization)
12
11
10
Kaolin production
10
Kaolin is a general name for minerals
such as kaolinite and halloysite, which
are mainly used in paper filling and coating,
as well as plastics, rubber and paint.
8
9
8
Solvent Extraction
Electrowinning
Solvent Extraction
Solvent Extraction
PURIFICATION AND METAL RECOVERY
9
8
Concentrate
9
Kaolin is often described as primary or
Anode Slimes
CRUD
secondary
kaolin deposits, which9 define
Anode Slimes
CRUD
8
Solvent Extraction
Cathode
Electrowinning
Electrowinning
Electrowinning
Cathode
Cathode
Cathode
Kaolin Production
Concentrate
Concentrate
Leaching
Impurity Removal
(Reduction, Precipitation,
Concentrate
Thickening
Cementation, Crystallization)
11
Mining
Crushing
Leaching
Blunging
Impurity Removal
Degritting
Leaching
Classification
Separation
Waste /Magnetic
Residue
Impurity Removal
10
Leaching
Fine product
Impurity Removal
Waste / Residue
10
Grit
Kaolin
Waste / Residue
10
Flotation/
(Reduction, Precipitation,
Selective Flocculation
Thickening
Cementation, Crystallization)
11
(Reduction, Precipitation,
T
Cementation, Crystallization)
Waste / Residue
10
Dewatering
Coarse product
Water
Solid fraction
Crushing
Mining
Calcination
Lime slaking
Lime tank
Fuel and air
Water
Carbonation
Dewatering
Calcium Carbonate ore
CO2
Solid
fraction
Precipitated
Calcium Carbonate
(PCC) Production
Packaging
Fine grinding
Water
Drying
MINING / BENEFICIATION
MINING / BENEFICIATION
EXTRACTION & CONCENTRATION
EXTRACTION & CONCENTRATION
Solid-Liquid Separation
Solid-Liquid Separation
Leaching / Digestion
Leaching / Digestion
Pregnant Liquor
Pregnant Liquor
4
Screening /Washing
Screening /Washing
Surface Mining
Surface Mining
2
2
4
Precipitation
Precipitation
Precipitates /Concent
Precipitates /Concent
Tailings
Tailings
Flotation
Flotation
Crushing
Crushing
Grind
Grind
Fines Rejects / Slimes
Fines Rejects / Slimes
Thickening
Thickening
6
6
Concentrate
Kaolin production, like calcium carbonate the drying process, which is often an
separation
means we can provide you with
energy-intensive process.
Tailings
production, requires a final dewatering
an
optimized
design for your application.
Tailings
Underground Mining
Underground Mining
in order
to minimize the cost for final
Besides a unique bowl geometry and
drying of the product. Consequently,
Coarse Reject
Tailings Pond / Dam
Coarse Reject
Tailings Pondprotection
/ Dam
Efficient
MINING / BENEFICIATION
an inlet zone to ensure gentle accelethe process benefits are similar to those
Tailings Pond / Dam
Pond / Dam
/ Digestion
and
high
reliability
ration Tailings
of the
slurry, we can offerLeaching
higher
of decanter installations in calcium
PURIFICATIONgrade
AND METAL
RECOVERY to protect the bowl and
materials
With more than 100 years of experience,
carbonate applications.
PURIFICATION AND METAL RECOVERY
conveyor. We can also offer economical
Anode Slimes
CRUD
Alfa Laval brings
you cleaner and more
Anode Slimes
CRUD
Screening /Washing
options for less aggressive, less erosive
The product can be dewatered to a Surface Miningefficient solid-liquid separation. Our accu2
slurries if this is a priority.
mulated expertise in industrial minerals
higher dryness, minimizing the cost in
1
1
Concentrate
3
3
5
8
8
Solvent Extraction
Solvent Extraction
9
5
Solid-Li
4
9
Electrowinning
Electrowinning
Flotation
Cathode
Cathode
No matter what the Grind
solution, all the critical
parts
we
provide
are
made of wear and
Key benefits:
Fines Rejects / Slimes
Concentrate
Concentrate
corrosion-resistant
material.
There are
• Concentrate
A solid fraction with low water content means lower drying costs
also options to include tiles that provide
• High flexibility – decanters can be applied in classification and dewatering
Tailings
extra conveyor
protection, or cleaningLeaching
Impurity Removal
Drying
Underground
Mining
3
Leaching than competing
Impurity Removal
Drying
Filtration
• Lower power consumption
separation technologies such
1
Filtration
Thickening
in-place (CIP)
programs
especially
Thickening
as plate-and-frame filters
adapted
to the specific application.
Waste / Coarse
Residue Reject
Tailings Pond / Dam
• Unmatched separation efficiency facilitated by our special
Waste / Residue
deep-pond technology
Ta
Calcining
Calcining
• Small installation space – the largest capacity per installed area
• Continuous, automatic operation instead of batch operation
PURIFICATION AND METAL
• Enclosed process means a greatly improved working environment.
Crushing
(Reduction, Precipitation,
(Reduction,
Precipitation,
Cementation,
Crystallization)
Cementation, Crystallization)
12
12
11
11
10
10
Anode Slimes
9
CRUD
8
Solvent Extraction
Electrowinning
Cathode
Concentrate
Leaching
Dewatering
Drying and
Calcination
Impurity Removal
(Reduction, Precipitation,
Packaging
Cementation, Crystallization)
Waste / Residue
10
Water
Solid fraction
Drying
Packaging
Samples from a dewatering test on calcium carbonate. The inlet slurry (left) is separated into the solids
fraction (middle) and liquid fraction (right) in an Alfa Laval decanter centrifuge. Parameters such as
bowl speed, pond level setting and differential speed can be changed in the decanter to meet targets
for solid-fraction dryness, particle size and separation efficiency.
Alfa Laval's decanter centrifuges are the perfect choice for treating
calcium carbonate, kaolin and other non-metallic minerals slurries.
High torque – low power consumption
Separation is often performed at high
solid loads and the minerals are very
dense. The backdrive system must
produce a high torque as well as a
high differential speed to scroll out
the dry solids and keep the liquid clean
– or, in a classification application, to
maintain efficient and exact separation.
Alfa Laval’s gearbox provides both the
required torque and scrolling rate, while
also ensuring the lowest possible power
consumption.
Automatic control
The 2Touch control system automatically
adjusts operation of the decanter according to changing conditions, such as
variable flow rates and solids concentration. This guarantees a very dry solids
fraction, accurate classification, stable
operation and minimum wear and tear.
Maintenance and service
Wherever you are, support from Alfa
Laval is never far away. Our worldwide
network of sales companies, service
organisation and field service engineers
are ready to provide assistance, rapid
support and ongoing optimization.
Our close cooperation with customers
in nearly 100 countries is a source of
valuable feedback for our research and
development team, giving us an edge
in the development of market-leading
technology.
Design based on experience
Our decanters are designed based on
experience, knowledge and testing in
laboratory and field environments to
optimize your specific processes, setting
a framework for scaling up to meet your
exact requirements and specifications.
Alfa Laval has a wide range of test
equipment and resources available to
suit the vast range of applications in
the mining and mineral industry.
Selected references
Alfa Laval has full-scale references worldwide for different
applications and has also carried out extensive testing and
laboratory analysis on numerous types of slurry.
Country
Decanter
Year
Application
India
P2-300
2011
Calcium carbonate
India
P2-405
2015
Kaolin
France
P2-500
2009
Calcium carbonate
Malaysia
P2-405
2016
Kaolin
At MS Sawa Clay & Minerals in Rajasthan, northern India,
five Alfa Laval decanters are installed in parallel to handle the
classification process, separating two-micron particles from
coarser material. The customer is very happy with the separation
efficiency, and thanks to good communication during the entire
engineering of the project, Alfa Laval’s design recommendations
were adopted to achieve the highest possible process efficiency.
PEP00245EN 1611
How to contact Alfa Laval
Up-to-date Alfa Laval contact details for all countries are
always available on our website at www.alfalaval.com.
Alfa Laval reserves the right to change specifications without prior notification.