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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 .
It is used for infrastructure, vehicles, aviation, energy and more due to its lightweight, ductility, and cheap cost. Aluminum is harvested from gibbsite, boehmite, and diaspore which make up bauxite. [2] The aluminum cycle is the biogeochemical cycle by which aluminum is moved through the environment by natural and anthropogenic processes.
The liquid aluminium is removed from the cell via a siphon every 1 to 3 days in order to avoid having to use extremely high temperature valves and pumps. Alumina is added to the cells as the aluminum is removed. Collected aluminium from different cells in a factory is finally melted together to ensure uniform product and made into metal sheets.
This is due to a majority of the aluminium in the ore being dissolved in the process. [2] Energy consumption is between 7 to 21 gigajoules per tonne (0.88 to 2.65 kWh/lb) (depending on process), of which most is thermal energy. [3] [4] Over 90% (95-96%) of the aluminium oxide produced is used in the Hall–Héroult process to produce aluminium. [5]
Acidic precipitation is the main natural factor to mobilize aluminium from natural sources [180] and the main reason for the environmental effects of aluminium; [207] however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air. [180] In water, aluminium acts as a ...
It involves re-melting the metal, which is cheaper and more energy-efficient than the production of virgin aluminium by electrolysis of alumina (Al 2 O 3) refined from raw bauxite by use of the Bayer and Hall–Héroult processes. Recycling scrap aluminium requires only 5% of the energy used to make new aluminium from the raw ore. [2]
Once the aluminium anode is consumed by its reaction with atmospheric oxygen at a cathode immersed in a water-based electrolyte to form hydrated aluminium oxide, the battery will no longer produce electricity. However, it is possible to mechanically recharge the battery with new aluminium anodes made from recycling the hydrated aluminium oxide.
Mass flow rate is defined by the limit [3] [4] ˙ = =, i.e., the flow of mass through a surface per time .. The overdot on ˙ is Newton's notation for a time derivative.Since mass is a scalar quantity, the mass flow rate (the time derivative of mass) is also a scalar quantity.