Municipal waste - state-of-the-art metal recovery
The Elbisgraben landfill site is home to Switzerland's most modern metal recovery plant, which removes raw materials from municipal waste residues and puts them to new use. It achieves an efficiency far above the legal requirements, as the operators emphasize.
Aluminum tubes, tin cans and other metals belong in the separate collection and not in the garbage bag. According to the Construction and Environmental Protection Directorate of the Canton of Basel-Landschaft, this recyclable fraction accounts for around 10.5 percent of the total weight of municipal waste incineration residues in the region. Each kilo of slag contains slightly more than 100 grams of metal, according to the data. Two-thirds of this is iron and one-third is so-called non-ferrous metals - including aluminum and copper, but also stainless steel or smaller amounts of silver and gold.
Environmental legislation prescribes the recycling of metals. According to the Swiss Waste Ordinance (VVEA), the landfill material may only contain a maximum mass fraction of 1 percent non-ferrous metal and stainless steel.
Pioneer plant designed
According to its own information, the canton of Basel-Landschaft has had a metal recovery plant designed for the Elbisgraben landfill site in Arisdorf that achieves far better efficiency and thus serves as a model for Switzerland. It has been in operation since September 2019 and is 2021 in its material flows of Rainer Bunge, Institute for Environmental and Process EngineeringOST Ostschweizer Fachhochschule, has been evaluated. With this plant, it is possible to reduce the metal content of the landfilled slag to only 0.08 percent for non-ferrous metal and 0.05 percent for stainless steel.
The granulation of the slag and the handling of the stainless steel are cited as success factors. The more the slag is crushed, the smaller the metal particles captured. The Elbisgraben plant reduces the grain size of the slag to 5 millimeters (previously 12 millimeters). In addition, it separates the stainless steel in the cycle, since it cannot be sorted out either by magnets or by so-called eddy current separators, which only act on other types of metal, as the Construction and Environmental Protection Directorate emphasizes.
This "urban mining" is much more environmentally friendly than mining. Material cycles are closed and natural deposits are conserved. Two-thirds of the environmental benefit of metal recovery in the Elbisgraben would come from fulfilling the legal obligation. The additional output of the plant corresponds, for example, to the total annual environmental impact of 1,200 people, it concludes.
Source: Building and Environmental Protection Directorate, Canton BL
The operation of the plant here in the video
