Using mixture design of experiments to assess the environmental impact of clay-based structural ceramics containing foundry wastes

authors	Coronado, M; Segadaes, AM; Andres, A
nationality	International
journal	JOURNAL OF HAZARDOUS MATERIALS
author keywords	Foundry waste; Recycling; Design of experiments; Chromium; Immobilization
keywords	RESPONSE-SURFACE METHODOLOGY; FLY-ASH; SPENT CATALYST; PROCESS OPTIMIZATION; SINTERING BEHAVIOR; TRIAXIAL PORCELAIN; LEACHING BEHAVIOR; THERMAL-TREATMENT; WATER-TREATMENT; PHASE-DIAGRAMS
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. (C) 2015 Elsevier B.V. All rights reserved.
publisher	ELSEVIER SCIENCE BV
issn	0304-3894
year published	2015
volume	299
beginning page	529
ending page	539
digital object identifier (doi)	10.1016/j.jhazmat.2015.07.010
web of science category	Engineering, Environmental; Engineering, Civil; Environmental Sciences
subject category	Engineering; Environmental Sciences & Ecology
unique article identifier	WOS:000367411000060