Waste from aluminum production mosaic
These photos show red mud, a waste product generated when aluminium is extracted from bauxite.
ALUMINIUM
Aluminium is a widespread metal, valued for being both lightweight and durable.
Aluminium's properties make it ideal for food packagings like kitchen foil and drinks cans.
Another important use of aluminium is in vehicle manufacture. Cars, trains, and planes often have frames constructed from aluminium.
Aluminium is widely recycled, with up to 81% of Europe's aluminium being reused each year.
But demand for aluminium is increasing, and much is still produced from scratch from rocks known as bauxite.
The production of aluminium from bauxite is an energy-intensive process, resulting in significant emissions of greenhouse gases.
Photo by Kier In Sight on Unsplash
Photo by James Yarema on Unsplash
In China, the world's leading producer of aluminium, 21 tonnes of carbon dioxide are released for each tonne of aluminium produced.
Recycling aluminium requires 95% less energy than producing it from scratch.
BAUXITE
Aluminium is the most widespread metal on Earth, comprising 8% of the total mass of our planet.
But aluminium does not occur naturally in its 'pure' elemental form, and so must be extracted from rocks known as bauxite.
Bauxite is a sedimentary rock with a distinctive red tinge. It is particularly prevalent in Australia, China, and Guinea.
The production of aluminium from bauxite takes place in two stages.
The first stage is known as the Bayer Process. It involves heating bauxite with sodium hydroxide in a pressure vessel. The Bayer process allows for the extraction of aluminium oxide from bauxite; separating it from waste products known as ‘red mud’.
The next stage is to smelt the aluminium oxide to produce pure aluminium. Smelting also gives off carbon dioxide as a waste product.
Photo by Michael Martinelli on Unsplash
Photo by Kier In Sight on Unsplash
RED MUD
Red mud is the common term used to describe bauxite residue. It is the main by-product released when aluminium oxide is extracted from bauxite.
Thick, red, and sludgy: red mud is an environmental pollutant and a risk to human health.
Red mud varies in composition, depending on the type of bauxite it is derived from.
Typically, red mud contains large quantities of silica, iron, and unextracted aluminium. It will also contain trace elements like arsenic, cadmium, mercury, and uranium.
One of the main risks posed by red mud is that it is alkaline, with a pH of 9.
In 2010, an accident at the Ajka alumina plant in Hungary resulted in 40 square kilometres of red mud spillage, killing 10 people.
Over 150 local residents were injured, with many suffering caustic burns from the red mud’s alkalinity.
Red mud also poses a threat to aquatic ecosystems: even small leakages of red mud can disrupt the pH of watercourses, endangering the survival of plant and animal species.
Magyar: Közigazgatási és Igazságügyi Minisztérium, Kormányzati Kommunikációért Felelős ÁllamtitkárságEnglish: Ministry of Public Administration and Justice, Ministry for Government Communication, Copyrighted free use, via Wikimedia Commons
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