Recovery of copper from metallurgical sludge by combined method of acid leaching and biosorption

A novel combined acid leaching-biosorption process has been designed and applied to recover Cu from metallurgical sludge. Cu was firstly leached out and then selectively adsorbed from lixivium by using modified sugarcane bagasse (SCB) fixed-bed column. Leaching results by HNO3 showed that 96.9% Cu along with different leaching ratios of Mg, Ca, Zn, Fe, Cd, Pb, K and Cr were dissolved into the lixivium from the sludge. Three types of breakthrough curve including inversed-L (for Mg, Ca, Fe, K and Cr), overshoot (for Zn, Cd and Pb) and S type (for Cu) were observed when the pretreated lixivium passing through the column, and adsorption kinetic results showed that the amount of Cu, Zn, Cd, Pb, Mg, Ca, Fe, K and Cr adsorbed was 16.6, 1.03, 0.04, 0.01, 0.03, 0.01, 0.77, 0.018 and 0.001 mg g(-1), respectively. Adsorption mechanism illustrated that Cu was selectively adsorbed from the lixivium due to its strong coordination ability with amine groups on the sorbent surface and the corresponding substitution reaction (between Cu and the co-ions). Cu could be recycled and the modified sorbent could be used repeatedly after column regeneration. These combined method had great potential in application of Cu recovery from sludge. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.