Stabilization/solidification of ashes in clays using for the manufacturing of ceramic bricks

C. GARCÍA UBAQUE, J. C. MORENO PIRAJÁN, L. GIRALDO, K. SAPAG

Waste Managment & Research

ISWA

Lugar: London- UK; Año: 2007 vol. 25 p. 1 - 15

0734-242X

This paper presents the results of the lixiviation of metals from different mixes of fly and bottom ashes that have been stabilized and solidified in clays used in the manufacturing of bricks.  The ashes used for this study were obtained from a Hoffmann-type brick furnace adapted for the incineration of municipal solid wastes (MSW) during the manufacturing of ceramic breaks (process denominated from now on coincineration). The ashes were stabilized in clay in different proportions of the clay-ash mix (99:1, 95:5, 90:10, 80:20 and 60:40). Such mixes were used to manufacture bricks that were calcined at a temperature ranging from 50 to 1100°C. Clay, ashes and manufactured bricks were characterized using the techniques of X-Ray diffraction (XRD), Fluorescent X-Ray (XRF), Thermogravimetry (TG), Differential Thermal Analysis (DTA), Atomic Absorption Spectroscopy (AAS) and Scanning Electronic Microscopy (SEM). Additionally, TCLP (Toxicity Characteristic Leaching Procedure) lixiviation tests were performed according to EPA 1311 method for the determination of heavy metals. The results showed an affinity between clay and ash, and also that the bricks manufactured with these mixtures presents low lixiviation levels. The tests also showed that the mixtures 95:5, present a greater concentration decrease, for most of the heavy metals tested, independent of the toxicity of the compound. Selenium is the metal with lower concentration change against Arsenic, Nickel, Chromium, Zinc and Cadmium with great concentration change in all mixtures, excepting cadmium in the mixture 99:1.