hatch potshell blanket 150215
TRANSCRIPT
HATCH
MAGNETIC MOUNTED INSULATION BLANKETS
FOR ALUMINUM REDUCTION CELLS
INSULATING BLANKETS FOR CORNER BATH LEDGE
CONTROL IN ALUMINUM REDUCTION CELLS
Cold corners in Aluminum reduction cells may lead to frozen bath ledge extending over the cathode,
contributing to high current densities and advanced corrosion of the cathode surface.
1 2
Advanced
cathode wear
in corner from
high current
density beside
extended bath
ledge
Advanced corner wear
Potholes from unequal current distribution through cathode
Anode
Shadow
Potshell
Sidewall
Edge of frozen
bath ledge on
cathode
Potshell
Endwall
Corner Blankets:
To reduce frozen
bath ledge and
reduce peak
current density
in corners
Anode
Molten Bath
Metal Pad
Cathode &
Potlining
Bath Cover
Reduced frozen
bath ’Toe’ in
corners
Reduced Frozen
Bath Ledge on
sidewall
Corner
Blankets
Anode
Molten Bath
Metal Pad
Cathode &
Potlining
Bath Cover
Frozen bath
‘Toe’ on
cathode
Frozen bath ledge
on sidewall
Pot cross section Cathode Surface Corner
Anode
Shadow
Potshell
Sidewall
Edge of frozen
bath ‘Toe’ on
cathode
Potshell
Endwall
Cold Corners:
Area of high current
density and cathode
corrosion
Convenience: Hatch’s magnetically mounted insulation blankets (patent pending) are easily
applied or removed to the potshell external surface to accommodate changing heat transfer
requirements due to refractory wear, or changes in bath chemistry or potline amperage.
Effective: The Blanket eliminates natural convention cooling of the steel potshell to the
environment. The graph below shows theoretical heat transfer rates of insulation blankets
versus bare steel with natural convection cooling in ambient air (20 C).
Feature & Benefits of the Cooling Fins and Blankets
• Magnetically mounted potshell insulating blankets may be manually applied or removed to
carbon steel surfaces without need of welding or bonding materials.
• Blankets are available in small (~350x350 mm), or large (600x600mm, or custom sizes.
• Blankets are non combustible silica cloth with rare earth magnets (350C max operating
temperature corresponding to ~450 C shell temperature under the blanket).
• Blankets can reduce the frozen bath toe over the cathode which reduces local high current
density which contributes to:
o magnetic force induced metal velocity and turbulence in the metal pad and
o high rates of current induced cathode corrosion
• The use of Hatch insulating blankets and cooling fins allow a balancing of the inner potshell
temperature, with less temperature variance, which may allow operating the cell with lower
bath superheat.
270C 330C
350C
Internal view Double
layer
Single
layer
Laboratory testing of a heated steel
shell demonstrates by infrared
imaging the internal surface
temperature of the steel shell under
single and double layers of the Silica
cloth, and under the bare metal
surface. The blankets effectively
raise internal shell temperatures.
Photo Reference: 1. Century Aluminum, Light Metals 2004
2. Hydro Aluminum, Norway Today
Please contact Hatch to trial or obtain the magnetically mounted insulation
blankets.
Canadian Patent PCT CA2014/051178, int’l patents pending.
Will Berends
Hatch Ltd.
2800 Speakman Dr.
Mississauga, ON,
Canada, L5K 2R7
www.Hatch.ca