Classification and statistical analysis of mine spoils chemical composition from Oliete basin (Teruel,NE Spain)

The Oliete basin (Early Cretaceous, NE Teruel, Spain) is one of the most important areas for the supply of mine spoils used as ball clays for the production of white and red stoneware in the Spanish ceramic industry of wall and floor tiles. This study corresponds to the second part of the paper published recently by Meseguer et al. (Environ Geol 2008) about the use of mine spoils from Teruel coal mining district. The present study shows a statistical data analysis from chemical data (major, minor and trace elements). The performed statistical analysis of chemical data included descriptive statistics and cluster analysis (with ANOVA and Scheffé methods). The cluster analysis of chemical data provided three main groups: C3 with the highest mean SiO₂ content (66%) and lowest mean Al₂O₃ content (20%); C2 with lower SiO₂ content (48%) and higher mean Al₂O₃ content (28%); and C1 with medium values for the SiO₂ and Al₂O₃ mean content. The main applications of these materials are refractory, white and red ceramics, stoneware, heavy ceramics (including red earthenware, bricks and roof tiles), and components of white Portland cement and aluminous cement. Clays from group 2 are used in refractories (with higher kaolinite content, and constrictions to CaO + MgO and K₂O + Na₂O contents). All materials can be used in fine ceramics (white or red, according to the Fe₂O₃ + TiO₂ content).