158
D. Dreisinger et al.
Lead plating takes place over a 3-day cycle. Cathode thickness will be 18–20 mm
and will weigh between 160 and 200 kg. The tankhouse operates with lead starter
cathodes that weigh 8 kg which are fabricated in the lead smelting and casting facility.
Each electrowinning cell is provided with a hood and ventilation extraction system
to exhaust the acid mist generated by the electrowinning process. The collected acid
mist is passed through a scrubber to ensure lead levels to atmosphere do not exceed
allowable limits. The solution in the electrowinning circuit is maintained at 40 °C
by a heat exchanger.
An automated cathode harvesting and delivery to the furnace system is provided.
Cathodes are harvested and melted on a 24-h cycle. Cathodes are removed from the
electrowinning cells utilising the automated overhead crane and bale system. Onethird (15) of the plated cathodes are removed from each cell at a time. The bale is
designed to lift the cathodes and insert a drip tray below the cathodes to collect acid
solution. The cathodes are delivered by the crane to storage racks ahead of the cathode
wash station. From the storage racks, the cathodes are automatically transported into
the cathode wash station and cleaned with hot water sprays and dried. They are
then automatically conveyed to storage racks ahead of the lead melting furnace. The
storage rack has capacity for 750 cathodes which is sufficient to ensure a 12 h buffer
in the event of equipment problems. A robot is used to remove the cathodes from the
wash station and to load them onto the storage/transport rack.
Cathodes are removed from the racks (one at a time) by a robot which presents
the cathode to a second robot for automatic removal of the copper hanger bar. The
bar is then delivered to the cathode starter sheet casting machine for reinsertion in
the starter sheet.
Once the hanger bar is removed, the robot delivers the cathode to an induction
furnace for melting. Cathodes are delivered to the furnace at the rate of one per
minute.
Lead Melting and Casting
A 600 kW induction furnace is provided for melting the lead cathode. The furnace
is provided with two sets of metals pumps. One set delivers hot metal to the ingot
caster, the other delivers metal for cathode starter sheet fabrication.
The lead ingot caster is made up of multiple moulds which are attached and
rotated through the casting cycle by a chain conveyor. The ingot casting is fully
automated from receipt of molten lead to the stacking of cast ingots. Cooling water
and air are applied to the moulds for cooling the ingot. The ingots are ejected onto a
second conveyor and a robot stacks the ingots into bundles on the stacking conveyor
where they are banded. A hoist is used to remove the ingot bundles from the stacking
conveyor and a forklift is used to the deliver the bundles to a storage area adjacent
to the furnace building. The bundles will be shipped off-site by truck.
D. Dreisinger et al.
Lead plating takes place over a 3-day cycle. Cathode thickness will be 18–20 mm
and will weigh between 160 and 200 kg. The tankhouse operates with lead starter
cathodes that weigh 8 kg which are fabricated in the lead smelting and casting facility.
Each electrowinning cell is provided with a hood and ventilation extraction system
to exhaust the acid mist generated by the electrowinning process. The collected acid
mist is passed through a scrubber to ensure lead levels to atmosphere do not exceed
allowable limits. The solution in the electrowinning circuit is maintained at 40 °C
by a heat exchanger.
An automated cathode harvesting and delivery to the furnace system is provided.
Cathodes are harvested and melted on a 24-h cycle. Cathodes are removed from the
electrowinning cells utilising the automated overhead crane and bale system. Onethird (15) of the plated cathodes are removed from each cell at a time. The bale is
designed to lift the cathodes and insert a drip tray below the cathodes to collect acid
solution. The cathodes are delivered by the crane to storage racks ahead of the cathode
wash station. From the storage racks, the cathodes are automatically transported into
the cathode wash station and cleaned with hot water sprays and dried. They are
then automatically conveyed to storage racks ahead of the lead melting furnace. The
storage rack has capacity for 750 cathodes which is sufficient to ensure a 12 h buffer
in the event of equipment problems. A robot is used to remove the cathodes from the
wash station and to load them onto the storage/transport rack.
Cathodes are removed from the racks (one at a time) by a robot which presents
the cathode to a second robot for automatic removal of the copper hanger bar. The
bar is then delivered to the cathode starter sheet casting machine for reinsertion in
the starter sheet.
Once the hanger bar is removed, the robot delivers the cathode to an induction
furnace for melting. Cathodes are delivered to the furnace at the rate of one per
minute.
Lead Melting and Casting
A 600 kW induction furnace is provided for melting the lead cathode. The furnace
is provided with two sets of metals pumps. One set delivers hot metal to the ingot
caster, the other delivers metal for cathode starter sheet fabrication.
The lead ingot caster is made up of multiple moulds which are attached and
rotated through the casting cycle by a chain conveyor. The ingot casting is fully
automated from receipt of molten lead to the stacking of cast ingots. Cooling water
and air are applied to the moulds for cooling the ingot. The ingots are ejected onto a
second conveyor and a robot stacks the ingots into bundles on the stacking conveyor
where they are banded. A hoist is used to remove the ingot bundles from the stacking
conveyor and a forklift is used to the deliver the bundles to a storage area adjacent
to the furnace building. The bundles will be shipped off-site by truck.