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The main advantage of PCC is the fact
that much finer products can be produced at less specific energy
consumption than with conventional methods such as grinding.
In comparison with other natural fillers, the special feature
of PCC is that by altering certain parameters which have an
influence on the chemical reaction, the end product can be controlled
in a great variety of ways. The advantages of PCC products include
especially being able to control:
The morphological or crystalline shape.
The degree of aggregation or clustering of the particles.
The particle size or the size of the specific surface area.
PCC products are employed especially in the paper industry,
but also in the pharmaceutical, foodstuffs, plastics and rubber,
and paint industries. The paper industry uses PCC with a fineness
of approx. 60% < 2 µm as a paper filler. The particles
are elongated in shape (see figure below). For paper coating,
a product with approx. 90% < 2 µm is necessary. The
particles in this case are cubic or elongated prisms (see figure
below).
60% < 2 µm |
90% < 2 µm |
The flowchart below shows the PCC production
process stages:
| 1. |
Feed material = natural quarried
limestone |
| 2. |
Kiln; end product = CaO lumps
(quicklime) |
| 3. |
CaO bin |
| 4. |
Slaker: CaO + H2O
= calcium hydroxide (Ca(OH)2)
= slaked lime |
| 5. |
Screen to separate contaminants
and unslaked lime |
| 6. |
Cooling unit |
| 7. |
Bin for slaked lime |
| 8. |
Reactors (fed with cleaned
waste gas for the reaction) |
| 9. |
Reactors |
| 10 |
Bin for the end product |
| 11 |
Postscreening to separate
any not reacted calcium hydroxide |
| 12 |
Intermediate bin |
| 13 |
Filter press |
| 14 |
Dryer |
The dry PCC can subsequently be coated
with the Alpine Contraplex pin mill.
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