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Crusher
Pre-reduction plants
The raw material that is required for the
cement production process is quarried in
accordance with the characteristic raw
material data by blasting, extraction by
hydraulic excavators or ripping. The
pre-reduction plant breaks the extracted
material to the particle size required by the
downstream raw mill.
The raw material to be broken is delivered
to the feed hoppers of the crushing plant by
heavy trucks or other transport machines.
The discharge device underneath the feed
hopper then conveys the material at a
controlled flow rate to the crusher.
Depending on the material's properties and
the method of extraction, very different
types of crushing plant are used for
breaking the raw material.
Conveyors belts
Raw materials and additives are usually
transported by suitable conveyor belts to
bulk material blending or storage beds.
Subsequently they are conveyed either
directly to the grinding plants or to the flow
regulation bins.
All conveyor belts are designed and
dimensioned to suit the plant requirements
and material properties, having the
necessary troughing, the necessary
cleaning and safety devices and suitable
feed and transfer chutes.
Circular stockpile/circular blending bed
the compact, cost-saving solution
In relation to their space requirement,
circular stockpiles and circular blending
beds have a higher storage capacity than
longitudinal stockpiles and blending beds.
Moreover, the circular version has the
convincing advantages of lower costs for
the civil construction work, shorter
conveying distances and lower capital
expenditure for the machines and electrical
equipment. The continuous CHEVCON
stacking method allows the highest
blending effects to be achieved.
The CONESHELL stacking method is
usable in storage facilities where there is no
need for a high degree of blending. The
use of stockpiles and blending beds for
storing lumpy single and multi-component
raw materials has become a standard
process at cement plants.
Maximum throughput rates and drive
powers, smallest possible construction size
and high availability are the essential
demands on a cement raw material grinding
plant and also precisely the characteristics
of this new roller mill from Polysius.
Grinding/Drying
The QUADROPOL® has decisive
advantages that make it particularly
suitable for online operation. One is the 4
individual grinding rollers, whose bearing
assemblies are located outside the grinding
chamber, protected from dust and high
temperatures. The cambered geometry of
the grinding roller, proven in the classical
mill with double roller pair and with
outstanding wear resistance, was retained
for the QUADROPOL®. This geometry
results in long service lives and a constant
performance profile with regard to
throughput and energy requirement over
the entire lifetime of the grinding elements.
The compact QUADROPOL® is designed
for drive powers of up to and above 6 MW
while assuring high plant availability. With
its automatic changeover from 4 to 2-roller
operation, the mill provides high adjustment
flexibility for adaptation to changes in raw
meal requirement. In addition, the mill has
extremely maintenance-friendly design
features. For instance, the two opposite
grinding rollers can be swung hydraulically
out of the mill housing; the two roller units
remaining in the mill then continue the
grinding process.
Polysius roller mills integrate three work
operations in a single unit: drying, grinding
and separating. The separator is thus an
integral part of the machine and is
therefore mounted directly on the mill
housing.
Conveying/Metered feeding
The POLDOS® flow regulating conveyor
continuously conveys fine-grained bulk
materials such as raw meal or coal dust at a
controlled flow rate.
The POLDOS® is used for pneumatic
feeding of cyclone preheaters and for
dosing coal dust to the burners of the
rotary kiln and calciner.
The advantages of the POLDOS® are ·
high flow-regulation precision · calibration
during operation · low-maintenance
operation · low energy requirement and ·
uniform and trouble free metered feeding.
Blending/Storing
The tangential blending silo consists of the
silo shell, the distributing system, the inner
cone, the aeration surface with the
discharge systems, the central mixing
chamber, the aeration system and the dust
collection filter.
The raw meal is fed into the silo through the
distributing system. Compared to the
conventional blending silo, the number of
feeding arms has been increased and a
central in feeding point has been installed.
As the feeding arms are alternately
activated by a control system, it is not
possible for the coarser grain size fraction
of the raw meal to permanently fall straight
down onto the same point and form a pile of
large-sized material. The special silo filling
process thus already counteracts
segregation of the raw meal.
The new tangential blending silo has a
unique aeration floor which covers almost
the entire ring area at the bottom of the silo
and thus ensures optimum aeration of the
raw meal. The material can be fluidised and
extracted at all points of the silo floor. The
aeration floor is of modular and compact
design and can therefore be simply,
efficiently and thus cost-effectively installed.
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Heating
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Preheating
For every requirement an
optimally customised DOPOL
concept
In the case of the cement
industry, today's requirement
profile for the manufacturing
process is directed at high
production capacities with low
operating and capital expenditure.
For this reason, multistage
cyclone preheaters with integral
calciner and tertiary air duct are
indispensable components of
modern kiln lines.
Polysius offers preheater/calciner
concepts that are innovative and
nevertheless technically mature
for the production of white and
grey cement; for new plants as
well as plant conver-sions, and
tailored to the desired production
capacity - no matter whether this
is less than 1,000 or more than
10,000 tonnes per day.
Burning
These days, thanks to
optimisation of the precalciner
system, a large number of rotary
kilns fully meet the requirements
of the burning process with a
length to diameter ratio of up to
15:1.
With the POLRO® system from
Polysius, a kiln with these
dimensions can be built as a
two-support version.
The POLRO® rotary kiln has a
statically determined support
configuration on only two roller
stations and has a direct drive
system. The kiln shell with its
splined tyres rotates on
self-aligning rollers, which
automatically adjust themselves to
the momentary running
conditions. The kiln is directly
driven via the rollers of the
inlet-end roller station. This
system supersedes the previously
conventional girth gear and pinion
mechanism. The POLRO® is
rounded off by pneumatic inlet
and outlet seals, hydraulic axial
thrust system and air-cooled inlet
trough.
Thanks to the statically
determined support configuration,
this kiln design is characterised by
high operating reliability, minimal
maintenance and inspection
requirements and therefore very
low operating costs.
Cooling
Numerous innovative process and
design details derived from
extensive studies provide this
future-oriented clinker cooler with
outstanding mechanical and
process technological advantages.
The POLYTRACK® - a unique
combination of static, horizontally
positioned aeration floor and an
above-floor transporting system -
offers an extremely efficient
clinker transporting principle and
strict separation of transportation
and aeration functions, together
with
ideal transverse distribution of the
clinker, with the effect of uniform,
efficient cooling of all grain size
fractions over the entire width of
the cooler
extremely low construction height
very high thermal efficiency
a robust, low-wear and easy to
maintain design, with resultant
outstanding availability and
a consistently modular design.
These advantages make the
POLYTRACK® extremely
interesting for both new plants
and conversion retrofittings..
Storing
he circular stockpile for clinker is
the simplest solution for storing
free-flowing materials. There are
two design versions: a
space-saving, mechanically
advantageous stockpile with a
funnel-shaped floor and central
discharge or a flat-bottomed
stockpile requiring no soil
excavation, with up to 3 discharge
channels.
Conveging/metered feeding
The AEROPOL® is a pneumatic
vertical conveyor for fine-grained
materials. It conveys continuously
at low pressure, produces no dust
and has no moving parts in the
flow of material.
The AEROPOL® is used for
low-maintenance and
cost-effective feeding of silo
installations for raw meal, cement
and coal dust
Grinding
The proven energy-saving
grinding system.
One of the principal reasons for
the outstanding success of the
high-pressure grinding roll in the
cement industry is its low power
requirement. Today, this mill is
employed all around the world for
the grinding of cement raw
material, cement clinker and
granulated blast furnace slag.
Since the POLYCOM® was
introducted by Polysius onto the
market in 1985 more than 250
units have been sold, so that
almost half of the approximately
500 mills operating worldwide on
the interparticle comminution
principle bear the name
POLYCOM® and stand for "Made
by Polysius".
The popularity of this type of mill
is due to the excellent operating
results, the substantial reduction
in energy consumption with
resulting cost savings and the
enormous throughput increases
when incorporated into existing
conventional grinding plants.
POLYCOM® units are designed
for throughput rates of up to
1,300 tph. The mill feed material
can be dry or moist with a largest
feed grain size of up to 60 mm.
Storing/silos
Tangential silo
The tangential silo was specially
developed for the long-term
storage of very fine-grained bulk
materials - such as cement. All the
silo outlets are located in the
middle of the silo, beneath the
central cone. The discharged
material can be conveyed to
various packing and loading
facilities.
Flat floor silo
For storing free-flowing and
fluidisable materials the simplest
solution is the flat floor silo.
Compared with other types of silo,
the flat floor silo - due to its silo
floor inclination of only 15
degrees - has the best ratio of
storage volume to construction
height. Flat floor silos have
diameters of up to 16 m.
Cone silo
The cone silo is a storage silo with
very little mechanical equipment
and therefore with minimal
operating costs. Aeration units in
the outlet zone and a blower are
all that is needed to ensure
perfect discharge of material. The
inclination of the cone is so
designed that the stored material
slides down in mass flow without
needing aeration in the silo.
Multi-compartment silo
When producing composite
cements, the individual
components are stored in
separate silos before they are
blended. Combining these silos
into one unit presents distinct
advantages. The compartments of
a multi-compartment silo are thus
individual silos with
pressure-relieved outlet.
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