A New Added-Value Application for Steel Wire Drawing Mill Scale Waste in Stoneware Ceramic Products

Mill scale (MS) is a iron-rich waste generated in the wire drawing process with high iron content and is still mainly disposed in landfills. The scientific community has been studied its use in other applications such as pigments, concretes, among others. This work aims to study a new added-value application for MS—the development of coloured ceramic pastes. For this purpose, the influence of the added amount (0, 1, 3, 5 and 10 wt.%), the pre-treatment (milling + sieving at 212 μμm), the maximum firing temperature (from 1043 to 1165 °C) and the type of furnace (laboratory/industrial) were analysed on the sample’s characteristics. A dark grey stoneware product was obtained through the incorporation of 10 wt.% of MS and leaching tests conducted at pilot scale with cups confirmed its immobilization in the ceramic matrix. Furthermore, it was proved that the firing temperature can be reduced by about 100 °C without affecting the specimen’s characteristics. This reduction leads to a considerable decrease in the energy consumption upon firing, inducing economic and environmental advantages. Therefore, this work provides a new added-value application for MS and contributes to the reduction of virgin raw materials consumption and development of more sustainable stoneware products.