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Compared with limestone, quartz or kaolin, talc is a speciality
within the sector of filler minerals for the industry. Because
there are numerous types of talc which can differ quite dramatically
dependent on their provenance, the range of processing methods
and the applications for this raw material are infinitely wide
and varied.
Talc is characterised by the following features:
Flaky, laminar structure
Soft in substance (1 Mohs)
Water-insoluble
High degree of brightness
Resistant to chemical attack
Thanks to these characteristics, talc has become widespread
above all in two application areas:
Paper industry: as a filler and as a coating.
Plastics industry: as a filler for polypropylene, to increase
the stiffness and the natural stability.
Special applications can be found in the cosmetics, pharmaceutical
and ceramic industries.
There are two things which need to be taken into account when
processing talc: the high abrasiveness of the contaminants (quartz,
dolomite, etc.) of the otherwise soft talc, and preservation
of the laminar structure.
Because of this, it is mainly two systems which are used for
grinding talc:
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1. Table roller mills
such as the ALPINE
AWM, for producing medium qualities of between d
= 63 µm and d
= 20 µm.
The ALPINE table roller mill AWM
has the following advantages:
Extremely low energy requirement
Steep particle size distribution
Extremely wear-resistant |
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Legend
1 = Feed metering unit
2 = Rotary valve
3 = Table roller mill AWM
4 = Automatic reverse jet filter
5 = Throttle valve
6 = Fan
7 = Silencer
8 = Suction filter
9 = Control cabinet
A = Product feed
B = Endproduct |
2. For superfine grinding operations, ALPINE's AFG jet mill
has won high recognition on the world market. When equipped
with a multi-wheel classifier, the AFG jet mill can produce
high finenesses (e.g. d
= 1 µm) at high throughput rates. This is without doubt
the reason why our large jet mills (800/3 AFG and 1250/6 AFG)
have been adopted by every market leader on the talc sector.
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Multi-wheel classifier
We have been able to increase
the throughput rate yet again in a decisive way by building
the 1500/3 AFG - the largest jet mill (max. air flow rate
20,000 Nm³/h at 9 bar) in the world. All machines
are equipped with the patented megajet nozzles and operate
with hot compressed air, a measure which serves to increase
the throughput rate. |
Megajet nozzles |
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Legend
1 = Proportioning belt weigher
2 = Flap valve
3 = Fluidised bed opposed jet mill AFG
4 = Automatic reverse jet filter
5 = Rotary valve
6 = Fan
7 = Throttle valve
8 = Exhaust silencer
9 = Control cabinet
A = Feed product
B = End product |
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