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Processing
limestone
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Limestone (CaCO3)
is one of the most important, versatile and - in terms
of quantity - one of the most frequently used minerals.
It is used throughout the world, for example, in the plastics,
rubber, foodstuffs, chemicals and pharmaceuticals industries.
It is an important constituent of high-grade paper, for
which typical finenesses that range between 60 and 99%
< 2 µm are demanded. |
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These end-product finenesses are manufactured
using wet mills. And because limestone is a mass product,
the machines used for processing are often in a simple
design that is oriented to non-stop production. One of
these inexpensive machines suitable for processing superfine
mineral powder suspensions of medium viscosity is the
Alpine vertical agitated ball mill ANR. This mill is used
for single-pass mode in constant operation. In order to
optimise the brightness of the product and the service
life of the mill components, the mill can be lined with
ceramic elements. |
The system
schematic shows a classic application for the ANR mill: Superfine
processing of calcium carbonate slurry for the manufacture of
paper. As an option, the system can be supplemented by a dry
precrushing step with the Alpine table roller mill AWM and –
to permit other product applications – by a slurry drying
step with the long gap mill LGM, an impact dryer.
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1 = Feed metering for dry precrushing
2 = Rotary valve
3 = Table roller mill AWM
4 = Automatic reverse jet filter
5 = Fan
6 = Buffer – feed bin for wet processing
7 = Feed metering screw
8 = Slurry mixing tank on load cells
9 = Additives tank with metering pump
10 = Transfer pump
11 = Supply bin for wet grinding
12 = Feed pump for agitated ball mill
13 = Agitated ball mill ANR
14 = Safety screening machine
15 = End product tank |
16 = Feed pump for impact drying
17 = Impact dryer – long gap mill LGM
18 = Air heater
19 = Automatic reverse jet filter
20 = Fan to preheat the air
21 = Control cabinet
A = Feed < 20 mm
B = Feed < 45 µm from silo
C = Drain
D = Process water
E = Additives
F = Slurry transfer
G = Dry pulp transfer |
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