Resource potential of landfill mining in Germany
Considering the increasing scarcity and raising prices of both, energy raw materials and other raw materials, such as metals and minerals, the recycling and recovery of these materials from anthropogenic deposits is of increasing relevance. Regarding this, the potentials of phosphorous, ferrous and non-ferrous metals as well as high calorific fractions in old landfills are of mayor interest for landfill mining. Assuming 10 million tons of dumped sewage sludge in Germany, the phosphate portion in landfills can be estimated to approximately 1 million tons (as P2O5). Rough estimations of dumped metals revealed, that the annual German demand for ferrous and nonferrous metals could be covered for several years. Taking into account the dumped household and hazardous industrial waste, 124 % of the annual demand for iron, 54 % for aluminium and 142 % for ferrous metals can be satisfied, given by literature. Extended caclulations including the metals stock in former dumped construction waste revealed, that up to 720 % of the non-ferrous metals and 360 % of the annual ferrous metal demand of Germany could be covered. Further metal potential was found in metallurgical slag dumpsides were 16 million tons of slags have been generated from the production of iron, steel and nonferrous metals in Germany. Since part of the metals remains in the form of metallic inclusions, agglomerates of alloys or in oxidic form in the mineral slag, this old dump sites offer an interesting valuable material potential. From the energy point of view, the high calorific waste components such as wood, plastics or paper and cardboard could act as substitute fuel. Estimations show that 95 million tons of plastics, 83 million tons of iron and 13 million tons of non-ferrous metals have been disposed of in landfills since 1975. An estimation of the energetic potential for landfills in Germany showed that in Germany the potential energy content stored within the landfills is approximately 7,700 PJ. This energy quantity corresponds to about 50% of the German annual primary energy consumption. Since the recovery of the raw materials stored in the landfills is only possible by use of technically and logistically complex systems, the economics of such projects are, among others, tied to the price level of raw materials in the world market. If a noticeable raw material scarcity with corresponding price fluctuation at the international raw material markets occurs, then the importance of urban mining will also increase.