Primary aluminum production consumes vast amounts of energy and emits a lot of carbon dioxide. Recycling is particularly important in aluminum, as it saves a lot of energy compared to other materials. By recycling per ton of aluminum, 6-10 tons of carbon dioxide and up to 95 percent of the energy originally required are saved.
Occurrence of aluminum
Aluminum is the third most abundant element in the earth’s crust and the most abundant metal. It is almost exclusively found in bound form, with bauxite being the economically most important starting compound for aluminum production. The mining areas for bauxite are among others in Australia, China, Indonesia, Russia, India, and South America.
Environmental problems from mining to production
The mining of bauxite is a huge burden on the environment. In addition to the sometimes destructive mining, the production of primary aluminum produces 1.5 tons of iron-rich, alkaline red mud per ton of aluminum oxide using the Bayer process.
This can hardly be recycled and is usually only deposited in large basins. If stored correctly, it is harmless, but if a dam breaks, there is a danger on the one hand from its high proportion of highly alkaline sodium hydroxide solution and, in the long term, from its heavy metal components such as cadmium, arsenic, mercury, lead and chromium.
Primary aluminum is produced using an energy-intensive electrolysis process. To produce 1 ton of aluminum, between 13,000-20,000 kWh of electrical energy is required and 6-10 tons of CO2 are released. The energy requirement and CO2 emissions increase further through the transport and further processing of the raw aluminum.
Why recycling is important
By recycling per ton of aluminum, the aforementioned 6-10 tons of carbon dioxide and up to 95 percent of the energy originally required are saved. That is a huge difference, which is why recycling is so important.
However, aluminum recycling is not an easy process. Aluminum rarely occurs in its pure form but is mostly part of alloys. Since aluminum is a base metal, it is very difficult to separate it from the more noble components in the alloy. As a result, aluminum is lost during the recycling process and the quality does not quite match that of the primary aluminum.