You may not know it, but aluminum is all around us. We find it in different areas of our daily lives. There is a big difference between producing it and recycling it, both in terms of energy costs and pollutant emissions, and at M&M we are committed to recycling it. We tell you more about it below.
The importance of recycling
Aluminum has countless applications in our daily lives. It is used to protect food (aluminum foil, cans or in Tetra Briks), in doors and windows or in kitchen utensils and tools.
Currently, around 100 Mt of aluminum are produced every year, which implies a great expense of energy. It is estimated that, to produce one ton of aluminum from bauxite (a mixture of minerals containing various concentrations of hydrated aluminum oxides), 45560 kWh are consumed (WBG, 2004). However, it is possible to reuse aluminum at the end of its useful life, that is, to recycle it. In fact, it is estimated that 70% of all aluminum manufactured in the history of mankind is still in use.
In this post we will talk about aluminum recycling, a key element in our company, since at M&M our commitment to environmental sustainability is unwavering.
How is primary aluminum obtained?
Aluminum is the most abundant chemical element in the earth’s crust (8%) after oxygen (47%) and silicon (28%). However, it is not found pure in nature, but combines with oxygen and hydrogen to form oxides and hydroxides. These, in turn, are mixed with oxides of other metals, such as iron oxide and silicon oxide. Bauxite, a mineral with the above-mentioned composition, is the main ore of aluminum.
The production of primary aluminum is carried out in two main stages. In the first, bauxite is crushed, purified and calcined to produce pure aluminum oxide (alumina) in a process known as the Bayer process. In the second, the alumina undergoes an electrolytic reduction process. In this stage (known as the Hall-Héroult process), the aluminum oxide is separated into aluminum and pure oxygen.
The most relevant pollutants emitted in this activity are: on the one hand, perfluorocarbons (PFCs), such as perfluoromethane (CF4) and perfluoroethane (C2F6); and on the other hand, SO2, CO, CO2, Cd, Ni, Zn and polycyclic aromatic hydrocarbons (PAHs) (SEI, 2014).
As a curious fact: four tons of bauxite are needed to produce one ton of aluminum. In addition, the Hall-Héroult process consumes around 15 MWh per ton of aluminum, (the equivalent of five million LED light bulbs lit for one hour) and emits approximately 1.6 tons of CO2 per ton of aluminum.
The aluminum recycling process
Aluminum recycling consists of different stages at the end of which the aluminum can be reused, obtaining a metal with the same properties as the initial one.
The first step consists of eliminating any magnesium that may be present in the material to avoid degradation problems. Subsequently, the material is melted using fluxing salts if necessary. It should be noted that the degree of aluminum recovery is higher if these fluxing salts are used because they form a layer on the aluminum that helps prevent oxidation. However, more salt slag is also produced.
The recycling process requires much lower amounts of energy than the primary route; energy savings are considered to be approximately 95%. In addition, emissions of CO2 and other greenhouse gases, such as PFCs, are also significantly reduced.
At M&M we are committed to cleaner, more efficient and environmentally friendly production. For this reason, the aluminum and other metal waste generated in our production process is collected and taken to a smelter for recycling.