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The first anode insulators were manufactured as a normal Rinotop
porcess. The product worked technically very well but later it appeared
that the product was not strong enough in all process conditions.
Plastic becomes brittle in acid as time passes. The first version was
hard but as said very brittle and was easily broken by a strong impact.
In the worst case, the lifter of the anode plates could be damaged and
the whole operation of the production plant could be interrupted. In the
process of the Kokkola factory, the Copper sulphate splashes
occasionally and adheres to the locking system of the separator. The
acid came inside the piece through a hole and copper sulphate started to
expand gradually by damaging the insulator as a result.
Requirements set to the new anode insulator made 2004:
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Acid-proofness. The recovery plants have a solution containing sulphuric acid and copper sulphate.
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Temperature resistance. In normal conditions, the temperature of the
process is about 50 degrees, but in exceptional cases it can rise up to
even 100 degrees.
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Mechanical strength. Lead anode plates of ca 100 kg are lifted from the
cam of the two anode insulators. In the export projects, hard treatments
of the anode insulators must be prepared for; a hammer is unknown in
many places and often a piece of iron or the like is used instead.
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The abrasion strength must be good.
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The material must not be conductive.
The development manager of Rinotop, Kari Kippilä summarizes:
- The implementation is a result of good cooperation with Outokumpu.
Rinotop was responsible for the 3-D modelling, the mould manufacturing
and the product manufacturing.
- The product dimensions were massive; many material tests and other
testings were done simultaneously with the mould design and the
machining; The best material showed to be the quality for film
fabrication, not the one intended for injection moulding. The
determination of the shrinkages was difficult due to the material and
the required wall thickness.
- The manufacture and the production required several tests. The
search for the manufacturing parameters was challenging due to the raw
material and the exact application. The production was divided into four
different places in accordance with a tough time schedule.
- End result: The customer got the insulators in time, the export
deliveries ready and packed in containers. The pieces also stand hard
treatment on work places. The whole project lasted from 17.2.2004 to
15.9.2004.