Nomenclature
Aluminate
A compound of aluminum and oxygen (Al 2 O 4 2- ) that is found in Bayer liquor in a precipitated or dissolved state after the digestion of bauxite.
Anode butt
Prebaked anode residue (comprising the rod, carbon residue and cryolite bath crust) consumed in the electrolytic cell.
Anode effect
Phenomenon causing a sudden increase in voltage and decrease in amperage in electrolytic cells due to the presence of a gas film on the surface of the anode.
Baghouse
Type of dust collector that uses filtering bags to capture particles contained in gas.
Bath/electrolytic bath
Molten liquid at a temperature of around 960 °C composed primarily of aluminum fluoride (AlF 3 ) and cryolite (Na 3 AlF 6 ).
Bauxite
Ore varying in structure, containing predominantly aluminum oxides, iron and silicon.
Bayer process/liquor
Process for the alkaline extraction of alumina contained in bauxite using Bayer liquor (solution of concentrated sodium hydroxide). Involves preparation and digestion of bauxite, settling of red mud, crystallization and precipitation of aluminate, and calcining of hydrated alumina.
Boehmite/gibbsite
Polymorphic aluminum oxides (AlO(OH), Al(OH) 3 ) making up bauxite.
Busbar
Low impedance conductor bars to which the electrical circuits of the electrolytic cells are attached.
Calcined coke
A form of petroleum coke having undergone the calcining step. Primary raw material of green/prebaked anode.
AQMS
Canadian policy on air quality management.
Casting centre
Facility in an alumina reduction plant where liquid aluminum from electrolytic cells is transformed into a semi-finished solid product.
Casting machine
System through which liquid aluminum is transformed into ingots, according to the required specifications.
Carbon dust
Carbon dust that accumulates in a cryolite bath, derived primarily from prebaked anodes.
Coal tar
By-product of carbon coking or gasification.
Cover material
Solid mix of alumina and crushed cryolite bath used to cover prebaked anodes after installation in the electrolytic cell. Also used to plug holes in the crust.
Crushed frozen bath
Crushed cooled cryolite bath, or a crushed mixture of cryolite, alumina and carbon recovered from anode butts.
Crust
Solidified bath and alumina mix covering the cryolite bath in electrolytic cells.
Cryolite
Main chemical compound (Na 3 AlF 6 ) of a cryolite bath in alumina reduction cells that reduces the melting temperature of aluminum.
Dry scrubber
Gas cleaning system consisting of several vertical reactors into which an adsorbent (calcined coke or alumina) is injected.
Dust collector
Processing unit designed to capture most particles contained in gas.
Enriched alumina
Alumina that has been used in the GTC or FTC to capture fluorinated gas. Enriched with fluorine.
Feeder/breaker
Automated system that feeds metallurgical grade alumina into electrolytic cells using a breaker that breaks the crust before injecting the alumina in the liquid bath.
FTC
Centre for the treatment of combustion gases from the baking furnace. Composed of a dry scrubber with alumina injection followed by a baghouse.
Green (petroleum) coke
Product derived from the delayed coking of refined crude oil.
Green anode
Compacted product of calcined coke and tar pitch after the casting and cooling of green paste.
Green paste (facility)
Section of the prebaked anode plant that produces green anode paste, a mix of calcined coke and tar pitch.
Grit blasting
Technique for cleaning a surface that consists of projecting microbeads on an object (anode butts) to break off cryolite bath residue.
GTC
Centre for the treatment of gases from alumina reduction cells. Composed of a dry scrubber with alumina injection followed by a baghouse.
Hard gray scale
Amorphous solid product of alumina, cryolite and water that accumulates on the inner wall of some ducts in a GTC or FTC that uses an alumina injection system.
Hydrated alumina
A form of alumina chemically bonded to water molecules (Al 2 O 3 ∙ x H 2 O).
Induction furnace
Furnace in which the heat required to melt metal is supplied through induction between two electric coils.
LMRC
Research and consultation centre on the smelting of aluminum, magnesium and other light metals based out of Auckland, New Zealand.
Metallurgical grade
alumina
alumina
A form of alumina containing very few or no water molecules (Al 2 O 3 ).
Packing coke
Calcined coke inserted in the pits of a kiln with green anodes to protect them against oxidation from the combustion air, while supporting good heat exchange.
PFTC
Centre for treating pitch fumes from the green paste facility. Composed of a dry scrubber with calcined coke injection followed by a baghouse.
Potroom
Building in which electrolytic cells connected in series are operated.
Pyroscrubber
Cleaning system specific to gases from the calcining of green coke that incinerates volatile organic compounds.
Red mud
Solid by-product of the Bayer process containing mainly iron oxides as well as aluminum, silicon, titanium, sodium and calcium oxides.
Sealed prebaked anode
Final product from the prebaked anode plant consisting of two blocks of anodes attached with cast iron to an electroconductive rod. Use in alumina reduction pots.
Sealing facility
Area of the prebaked anode plant where carbon blocks are attached to electroconductive rods.
Self-ignition
Occurs when the energy necessary for calcining comes from green coke alone, without an external fossil fuel.
Söderberg process
Alumina electrolysis process using carbon briquettes (or anode paste) characterized by its property to bake in situ in the electrolytic cell.
Superstructure
Facility containing electrolytic cells, hoods and a system that extracts gas to the GTC .
Taphole
Opening in the crust through which molten aluminum or cryolite bath is extracted from the pot.
Tar pitch
By-product of the distillation of coal tar used as a binder during the production of green paste.
Under-calcined coke
By-product of coke recovered by dust collectors from calcining gas released from the green coke calciner.
Venturi wet scrubber
Gas cleaning system that atomizes wash water, improving particle capture.