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Bayer process. 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]
Hall–Héroult process. The Hall–Héroult process is the major industrial process for smelting aluminium. It involves dissolving aluminium oxide (alumina) (obtained most often from bauxite, aluminium 's chief ore, through the Bayer process) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell.
Aluminium smelting. 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.
Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt. Al 2 O 3 + 6 HF → 2 AlF 3 + 3 H 2 O Al 2 O 3 + 2 NaOH + 3 H 2 O → 2 NaAl(OH) 4 (sodium aluminate)
Water-reactive substances[1] are those that spontaneously undergo a chemical reaction with water, as they are highly reducing in nature. [2] Notable examples include alkali metals, lithium through caesium, and alkaline earth metals, magnesium through barium. Some water-reactive substances are also pyrophoric, like organometallics and sulfuric ...
The chemical formula for TEOS is given by Si(OC 2 H 5) 4, or Si(OR) 4, where the alkyl group R = C 2 H 5. Alkoxides are ideal chemical precursors for sol–gel synthesis because they react readily with water. The reaction is called hydrolysis, because a hydroxyl ion becomes attached to the silicon atom as follows: Si(OR) 4 + H 2 O → HO−Si ...
Atomic layer deposition. Schematic illustration of one reaction cycle of the ALD process, using the trimethylaluminium (TMA) -water process to make thin aluminium oxide films as (simplified) example. There, the starting surface contains hydroxyls (OH groups) as reactive sites; Step 1 is the reaction of TMA; Step 2 is a purge or evacuation step ...
A high-purity (≥99.9998%) aluminium bar that has been etched to reveal the component crystallites. Chemical milling or industrial etching is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. [1][2] Other names for chemical etching ...