Recycling of steel plant by-products is a critical area that needs careful assessment and development if the integrated steel plant is to remain environmentally and economically sustainable into the future. A research program is being embarked upon in the Australian Steel Research Hub with aims to realise the value of the by-products to the Australian Steel industry and minimise volumes being stockpiled. As a first step, key by-product streams (such as blast furnace, BOS and sinter dusts) are being evaluated and characterised so that their potential uses in-plant or elsewhere can be assessed/evaluated. These streams contain components including iron and zinc units which have value on plant and elsewhere. Realising the value in these streams by recycling or other processing will help to minimise emissions and reduce costs by replacement of raw materials and reducing the amount going to stockpile. In this paper, microscopy (SEM and EDS analysis), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of a by-product material are presented and discussed with a view of understanding the behaviour of the material in use and on plant and its limits for further processing.