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

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.