Demonstration Plant Equipment Design and Scale-Up from Pilot Plant of a Leaching and Solvent Extraction Process

摘要

Germanium recovery from coal fly ash by hydrometallurgical procedures wasstudied at the pilot scale (5 kg of fly ash/h). Results were used to design the equipment of ademonstration-sized plant (200 kg of fly ash/h). The process is based on hydrometallurgicaloperations: firstly a germanium extraction from fly ash by leaching and a consequent Geseparation from the other elements present in the solution by solvent extraction procedures.Based on the experimental results, mass balances and McCabe-Thiele diagrams were appliedto determine the number of steps of the solvent extraction stage. Different arrangements havebeen studied and a countercurrent process with three steps in extraction and six steps inelution was defined. A residence time of 5 min was fixed in both the extraction and elutionstages. Volumetric ratios in extraction and stripping were: aqueous phase/organic phase = 5and organic phase/stripping phase = 5, so a concentration factor of 25 is achieved. Mixersand decanters were completely defined. The maximum extracted and eluted germanium wasestimated and a global efficiency of 94% was achieved. The cost-effectiveness of theequipment was estimated using the Lang factors.