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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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