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Graphite is
a hexagonal or rhomboedrical grey-black mineral having
a high electrical conductivity and a hardness according
to MOHS of 1. Depending on the purity Graphite is used
for production of pencils, of casting molds, of electrods,
as lubricant as very light construction material, for
carbon fibres and a lot of other applications. Due to
the high demand Graphite is gained relevantly synthetical.
This socalled Electrographite is produced in special kilns.
Mainly Petroleum Coke is used as rawmeterial for this
process. New technics are using Asphaltite and achieving
nuclear pure Graphite.
Natural Graphite is found in three forms: mikrocristaline
Powdergraphite, makrocristaline Flake-graphite and amorphous
Graphite. The majority of Graphite is produced in China,
Southkorea, Czech Republic, India, Mexiko, Austria, Northkorea,
Brasil, Madagaskar and Germany.
Many new applications for example for Lithium batteries,
fuel cells, as a flame retardent in the form of Graphite
foil but the traditional fields for lubricants or as a
filler for rubber are asking for more fine powders.
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Therefore Hosokawa Alpine has developed
further the existing Fluidised Bed Opposed Jet Mill. This
new mill is called TTG
and integrates a new patented Turbo Twin classifier head.
Using the new designed classifier wheel very fine products
can be produced. Due to the higher airflow an improvement
in capacity in the range of 15 % can be realised in comparison
to the existing AFG. To use the MegaJet nozzles increases
the capacity by another 15 %. Finally load cells ensure
a more continous level control inside the mill and therefore
a more equal product quality.
The fines products to be gained from production sized
mills are in the range of d
= 1,9 µm and have a topcut of d
= 5,0 µm. With the TTG such ultrafine products can
be achieved but as well the standard fines 90 % < 60
µm.
Especially for manufacturing of batteries a steep particle
size distribution with high bulk density shall be used.
Due to the improved efficiency of the new classification
technology the particle size distribution of the fines
is more steep.
The use of MegaJet nozzles and the Turbo Twin classifier
head reduce the specific energy cost approximately 30
% an more. As natural Graphite and of course Electrographite
influenced from it's production process are different
in grindability the correct safes only can be determined
during grinding tests at our test centre.
Of course all AFG's of any year of manufacturing can be
upgraded with the new technology. |
Advantages:
easy and low cost upgrading at existing systems
extremely fine products can be produces
much lower production cost
steep particle size distributions achieveable
Available are the following machine sizes.
| Scale
up factor |
1
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2,5
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6,25
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12,5
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| Fines
d
[µm] |
2,5 – 50
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3 – 65
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3,5 – 80
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4 – 100
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Classifier
wheel- [mm] |
200
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315
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500
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710
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Max.
Classifier speed [min ] |
10.000
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7.300
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4.600
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3.250
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| MegaJet-Nozzles-[mm] |
8 / 9
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10 / 12
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18 / 21
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1)
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| Number
of nozzles |
3
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4
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4
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4
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1) Determined according to test result
The following comparison shall underline the capability
of the new technology. |
| Finest
Product d
[µm] |
1,9
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3,5
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| Picture of Fines with the internal
REM at the test centre of Hosokawa Alpine |
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