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Ing. Matthias Kraume on the occasion of his 65th birthday Over the past 35 years, the cost benefit of the economies of scale has led in some industrial production processes to a more than tenfold increase in reactor volume. The article highlights this trend with the focus on three industrial examples: PET production, pressure oxidizing in the mining industry, and fermentation. It gives background information about the current trend and shows industrial examples of the world's largest plants, often referred to as world-scale plants with their specific characteristics, challenges, and mixing and engineering solution.

As mineralogy has become more complex in the long history of hydrometallurgical processing, the process routes and equipment used had to adapt to the changing conditions [1]. Hydrometallurgical bioleaching processes have been developed for different key metals such as gold, nickel and copper amongst others, to overcome the limitations of leaching sulphidic ores. The core of such a hydrometallurgical bioleaching plant is a cascade of stirred atmospheric tank reactors. Large volumes of air that are blown into these tanks must be dispersed by the agitator in order to provide the necessary oxygen mass transfer rates. At the same time the agitator system must be able to properly suspend all solids, homogenize the vessel contents and remove the exothermic reaction heat by inner tube bundles to achieve optimal reaction conditions. Besides the ‘economies of scale’ and advances in process results, cost optimization of such systems is fundamental. Therefore EKATO has developed the Combijet+ technology which has significantly reduced power requirements, compared to conventional agitators. Another advantage of the Combijet+ technology is that the gas is injected directly into the highest shear zones, at the impeller blades. As a result the oxygen mass transfer is improved and also substantial cost savings for compressor power are possible. The technical paper will present EKATO’s Combijet technologies which support the next step towards a new generation of biohydrometallurgical processing plants. It will also give examples of large scale commercial applications where this technology is successfully in operation.

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