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Mixing Technology Urban Mining Made Profitable by Improved Mixing Technology

| Author/ Editor: Wolfgang Keller, Annette Rümmele, Dr.-Ing. Wolfgang Last* / Dr. Jörg Kempf

On first sight process requirements in urban mining seem to be much less complex as in the classical mining of primary ore bodies since numerous metals are available in high concentrations. Anyhow the presence of many different metals makes the separation to pure end products very demanding and complex.

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Fig. 3: 2.1 m diameter impeller with solid ceramic blades
Fig. 3: 2.1 m diameter impeller with solid ceramic blades
(Source: Ekato)

Besides the direct recovery of metals from waste the recycling from sources as tailings from former ore processing plants gets more and more common. This is mainly due to the fact that technological developments and state-of the-art production processes nowadays allow the reclaiming of these former dumps. Other aspects of the reprocessing of tailings are the extraction of by-products, which were previously not the main focus of the operators. In addition to the expansion of resources such reprocessing of heaps can also serve the protection and preservation of the environment, for example, if the uranium content is reduced or in sulfide ores, the uncontrolled formation of acid is suppressed. However, again the processing methods, especially in the extraction of additional metals, can again become quite complex.

Many of the established and new processes required recovering metals and other raw materials necessitates agitated process steps. Some of the many examples include the recycling of clothing, PET bottles and wood. When it comes to metals examples are the extraction of metals from batteries (e.g. lead), red mud (aluminum), gold tailings and the extraction of zinc or aluminum from fly ashes of waste incineration or coal fired power plants. Many of these recovery processes can be designed using available technologies and know-how, but some require the development of new technologies or process steps. This applies for agitation as for other unit operations as well. Many of the solutions provided rely on the experience and know-how of the equipment suppliers gained over many years for similar or related applications.