title: Using mixture design of experiments to assess the environmental impact of clay-based structural ceramics containing foundry wastes.
abstract: This work describes the leaching behavior of potentially hazardous metals from three different clay-based industrial ceramic products (wall bricks, roof tiles, and face bricks) containing foundry sand dust and Waelz slag as alternative raw materials. For each product, ten mixtures were defined by mixture design of experiments and the leaching of As, Ba, Cd, Cr, Cu, Mo, Ni, Pb, and Zn was evaluated in pressed specimens fired simulating the three industrial ceramic processes. The results showed that, despite the chemical, mineralogical and processing differences, only chrome and molybdenum were not fully immobilized during ceramic processing. Their leaching was modeled as polynomial equations, functions of the raw materials contents, and plotted as response surfaces. This brought to evidence that Cr and Mo leaching from the fired products is not only dependent on the corresponding contents and the basicity of the initial mixtures, but is also clearly related with the mineralogical composition of the fired products, namely the amount of the glassy phase, which depends on both the major oxides contents and the firing temperature.
authors.affiliation: Department of Chemistry and Process and Resources Engineering, University of Cantabria, 39005 Santander, Spain; Department of Materials and Ceramics Engineering (CICECO), University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Coronado
authors.affiliation: Department of Materials and Ceramics Engineering (CICECO), University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: A M
authors.initials: AM
authors.lastname: Segadães
authors.affiliation: Department of Chemistry and Process and Resources Engineering, University of Cantabria, 39005 Santander, Spain. Electronic address: andresa@unican.es.
authors.forename: A
authors.initials: A
authors.lastname: Andrés
keywords: Chromium; Design of experiments; Foundry waste; Immobilization; Recycling