Progressive Plant Extension Applied to the Soil Treatment Facility of the “Arge Ground Unit”, Particularly Enhancement of the Treatment Range and Optimization of the Product Flows: An Example for Successful Urban Mining

The wet-mechanical soil treatment plant (soil washing plant) of the consortium “Arge Ground Unit”, located at the industrial area Linz (Upper Austria), was extended progressively. Particular mineral processing techniques were applied for the enrichment of contaminants and a continuous optimization process was implemented, pertaining all material flows from coarse gravel fraction to filter cake. Considerable quality control improvement and cost reduction were achieved by optimizing the wet-mechanical soil treatment plant. Particularly the disintegration and pre-separation of low-density material from the contaminated input material, the efficiency of the process water cycle and the decontamination of the sand fraction 0/4 mm were improved significantly in regard to higher PAH-contaminated material from the high priority remediation site ‘Cookery Linz (O76)’. In addition, flotation tests were performed with contaminated sand and dewatered filter cake, which finally led to the final extension step of integrating a two-step froth floatation unit into the existing plant concept for the treatment of the highly-contaminated thickener sludge. Owing to the plant expansion, the CO₂ reduction within the operation period of 2009–2015 was in a considerable range of 2,280 metric tons. The current status and insights gained are subject of this technical note.