Processing of Polymetallic Materials Requires Flexible and …
755
Table 5 Operational experience and taken actions during first years after commissioning
Positive
Need improvement
Measures/Actions
• Better suction of kettles and
de-drossing units due to
better cover of kettles,
increased off-gas volume
and separate baghouse
• Less level handling at
kettles, reduced the casting
of intermediate blocks
• Better temperature control
due to kettle design, two
burners for each stand
• Frequency control for each
stirrer and pump
• Parallel de-drossing of
kettles possible
• Improved removal of Zn
deposit from vacuum lid
instead of vacuum bell
• Shorter ways on the shop
floor for crane works
(parking stands for pumps,
covers, and stirrers next to
kettles)
• Safer access to Harris
cylinder and working
platform
• Plugs next to every kettle
• Shop floor ground made of
special concrete, heat
resistant
• Casting speed
approximately 40 t/h
• Crane can reach all
necessary positions in the
refinery
• Possibility of installing a
second crane if required
• Quality of welding and
sealing at vacuum kettle
and lid in the beginning
• Time consuming procedure
to protect the cooling edge
of vacuum kettle by
installing a protection
shield at each batch during
removal of bismuth foam
• Temperature changes
during bismuth removal
process caused cracks at
cooling edge later on
• Installation of additional
kettle (No. 9) in 2018 to
separate de-zincing and
de-bismuthing process
• Due to the installation of a
separate de-bismuthing
kettle the de-zincing
process runs very stable
• No experience in
de-zincing parameters with
lid, no chance to take
samples
• Time controlled procedure
is preferred
(continued)
755
Table 5 Operational experience and taken actions during first years after commissioning
Positive
Need improvement
Measures/Actions
• Better suction of kettles and
de-drossing units due to
better cover of kettles,
increased off-gas volume
and separate baghouse
• Less level handling at
kettles, reduced the casting
of intermediate blocks
• Better temperature control
due to kettle design, two
burners for each stand
• Frequency control for each
stirrer and pump
• Parallel de-drossing of
kettles possible
• Improved removal of Zn
deposit from vacuum lid
instead of vacuum bell
• Shorter ways on the shop
floor for crane works
(parking stands for pumps,
covers, and stirrers next to
kettles)
• Safer access to Harris
cylinder and working
platform
• Plugs next to every kettle
• Shop floor ground made of
special concrete, heat
resistant
• Casting speed
approximately 40 t/h
• Crane can reach all
necessary positions in the
refinery
• Possibility of installing a
second crane if required
• Quality of welding and
sealing at vacuum kettle
and lid in the beginning
• Time consuming procedure
to protect the cooling edge
of vacuum kettle by
installing a protection
shield at each batch during
removal of bismuth foam
• Temperature changes
during bismuth removal
process caused cracks at
cooling edge later on
• Installation of additional
kettle (No. 9) in 2018 to
separate de-zincing and
de-bismuthing process
• Due to the installation of a
separate de-bismuthing
kettle the de-zincing
process runs very stable
• No experience in
de-zincing parameters with
lid, no chance to take
samples
• Time controlled procedure
is preferred
(continued)