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Straumsvik aluminum smelter, operated by Rio Tinto Alcan in Iceland. Aluminium smelting is the process of extracting aluminium from its oxide, alumina , generally by the Hall-Héroult process . Alumina is extracted from the ore bauxite by means of the Bayer process at an alumina refinery .
For ingots, book molds are often used, producing slabbed ingots suitable for remelting or rolling. [14] Continuous casting directly shapes the aluminium into rolling slabs without an intermediate ingot casting step. Twin-belt or twin-roll strip casting produces alloy strips 6-7mm thick directly from the melt for subsequent rolling.
The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer.Bauxite, the most important ore of aluminium, contains only 30–60% aluminium oxide (Al 2 O 3), the rest being a mixture of silica, various iron oxides, and titanium dioxide. [1]
The density of liquid aluminum is 2.3 g/ml at temperatures between 950 and 1000 °C (1750° to 1830°F). The density of the electrolyte should be less than 2.1 g/ml, so that the molten aluminum separates from the electrolyte and settles properly to the bottom of the electrolysis cell.
This is a list of primary aluminium smelters in the world. Primary production is the process by which alumina is smelted to pure aluminum. [1] Secondary production is the process of recycling aluminum scrap into aluminum that can be used again. [2]
Aluminium recycling is where pure aluminium products (previously used in another form) are re-melted into aluminium ingots and then re-used to new aluminium products. [9] While aluminium dross recycling is where the dross, a byproduct of the smelting process in the creation of aluminium from bauxite , can be mechanically recycled thus ...
Direct Chill casting is a method for the fabrication of cylindrical or rectangular solid ingots from non-ferrous metals, especially Aluminum, Copper, Magnesium and their alloys. The original ingots are usually further processed by other methods (rolling, forging, etc.). More than half of global aluminum production uses the Direct Chill casting ...
Ingot molds are tapered to prevent the formation of cracks due to uneven cooling. A crack or void formation occurs as the liquid to solid transition has an associated volume change for a constant mass of material. The formation of these ingot defects may render the cast ingot useless and may need to be re-melted, recycled, or discarded.