The dewatering of iron ore is a high tonnage application in general requiring high energy input. Choosing a ceramic capillary action disc filter can offer decreased specific energy consumption in addition to a fully regenerable filter medium. The aim of this study was to obtain new information on the fouling of the filter medium in an iron ore process to enhance and develop the regeneration process of the medium in the future. X-ray diffraction and scanning electron microscopy were used to characterise the chemical composition and the morphology of the different chemical components, respectively, of the filter media used in the dewatering of magnetite. Two types of media blockages were found to play an important role in an acidic iron ore dewatering process: fouling by slurry particles and by in-situ crystallisation of calcium oxalate, of which the latter originated from the combination of process water and process chemistry. The scale was dissolved with hydrochloric, nitric, and sulphuric acids, and with potassium hydroxide. The best results, i.e. highest quantity of dissolved calcium and increase in permeability of the filter medium, were achieved with 2 mol/L nitric acid. (C) 2013 Elsevier B.V. All rights reserved.