Australians use over three billion aluminium beverage cans annually, but only two billion end up in recycling plants. Fortunately, measures are in place to increase the number of aluminium cans recycled and save energy used to process new ores. However, recycling waste aluminium cans is quite tricky compared to other scrap metals because aluminium is non-ferrous. This article highlights the critical stages of recycling used aluminium cans.
Optical Sorting – Aluminium is one of the trickiest metals to sort because, unlike ferrous metals, it cannot be separated using a magnet. Thus, metal recycling plants use optical sorters equipped with infrared sensors to immediately identify the metal from the piles passing through a conveyor belt. Most importantly, the infrared sensors are connected to air supply nozzles along the conveyor belt, blowing away non-metallic materials such as glass and plastic. The mechanism ensures that only metals pass through the optical sorter. It is important to note that optical sorters that separate shredded aluminium cans from other materials must be fast-acting and highly sensitive. It prevents non-metallic materials from mixing and contaminating aluminium metal during recycling.
Powerful Magnet to Pull Other Metals -- Although the remaining pile is free of non-metallic materials, the chances are high that other metal types can be found within shredded aluminium cans. Since the aluminium recycling process is different from that of other metals, it is vital to separate the two. It is made possible through a powerful magnet located at the end of a conveyor belt. As the mixed metal pile falls to a catchment area, the powerful magnet sucks any steel scraps and other magnetic metals. Thus, only aluminium metal falls inside the catchment bin, ready for melting.
Vaporising Paint and Lacquer -- The paint and lacquer on the sides of aluminium beverage cans can contaminate the recycling process; therefore, removal is essential to the integrity of the finished product. Notably, the most effective way to remove the paint and lacquer is to vaporise them, which requires extremely high temperatures. Most people think that the temperatures vaporise the paint and lacquer and, at the same time, melt the shredded aluminium. However, it is not the case because aluminium does not melt until temperatures reach 660 degrees Celsius. Thus, the paint and lacquer are not so lucky since they easily vaporise way before temperatures reach aluminium's melting point. The process leaves behind clean aluminium chips that are melted and cast into towering blocks of aluminium called ingots.
For more information on scrap metal recycling, contact a recycling plant in your area.