Stabilization/solidification of ashes in clays used in the manufacturing of ceramic bricks

Abstract

This paper presents the results of the lixiviation of metals from different mixtures of fly and bottom ashes that have been stabilized and solidified in clays used in the manufacture of bricks. The ashes used for this study were obtained from a Hoffmann-type brick furnace adapted for the incineration of municipal solid waste during the manufacturing of ceramic bricks. The ashes were stabilized in clay in different proportions of 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 degrees C. The clay, ashes and manufactured bricks were characterized using X-ray diffraction, fluorescent X-ray, thermogravimetry, differential thermal analysis, atomic absorption spectroscopy and scanning electronic microscopy. In addition, toxicity characteristic leaching procedure lixiviation tests were performed according to the 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 present low lixiviation levels. The tests also showed the highest decrease in the concentration of arsenic, nickel, chromium, zinc and silver for 99:1 mixtures. The 95:5 mixture was found to be the most favourable for the stabilization (greater concentration decrease) of lead and cadmium. Selenium was the metal with the lowest concentration change whereas arsenic, nickel, chromium, zinc and cadmium showed the greatest concentration change in all mixtures, with the exception of cadmium in the mixture 99:1.

Manufacturing of building bricks without Portland cement

“…On the one hand, many studies have considered the use of FA as a raw material in brick manufacturing. On the other hand, avoiding energy consumption has not been the focus of these studies (Cicek and Tanriverdi, 2007;Tokyay and Cetin, 1991;Garcia-Ubaque et al, 2007;Xu et al, 2005;Chou et al, 2001). In these studies, the production of masonry bricks requires additional energy because of the firing or steam curing of the samples.…”

Uso de resíduo da produção de alumina eletrofundida na produção de blocos e telhas cerâmicos

“…Assim, evidencia-se que a capacidade de absorção de resíduo pelas massas cerâmicas não está apenas associada a sua composição química, mas também a sua granulometria, sendo necessário que o resíduo que vá atuar como material não plástico (e inerte) tenha granulometria semelhante as das matérias-primas não plásticas convencionais [17]. Um resíduo que apresenta granulometria semelhante ao do resíduo do pó de coletor estudado é a cinza volante, no entanto é possível a incorporação de grandes quantidades desse resíduo em formulações cerâmicas para produção de blocos e telhas em virtude de sua elevada reatividade e poder fundente [26,27] nas temperaturas utilizadas para a produção de cerâmica estrutural. Com a queima ele funde ou reage com a massa argilosa e assim, possíveis efeitos de diminuição do empacotamento podem ser "compensadas" durante a queima.…”

Environmental suitability of ceramic raw materials: a geochemical approach to volatile emissions and leaching potentials

“…The inertization of hazardous industrial waste into a ceramic matrix is widely pursued, being considered an environmentally acceptable solution (Domínguez and Ullmann 1996;Dondi et al 1998Dondi et al , 2002Cheesman et al 2003;García Ubaque et al 2007;Singh et al 2007;Chiang et al 2008;Lafhaj et al 2008). However, caution is needed particularly in the case of products containing significant amounts of easily volatile or leachable elements.…”

“…These tests incude measuring physical and chemical characteristics of clay bodies, as well as their responses during the ceramic process (Murray 2007). However, the use of unknown raw materials involves potential contamination, especially in the case of industrial by-products and residues, which requires a preliminary assessment to prove that the ceramic body actually incorporates the pollutant and that no harmful elements are released as volatile emissions during processing (Dondi et al 2002;Galán et al 2002;Xie et al 2003;Cusidó et al 2003;García-Ten et al 2006) and/or as leachate from the finished product (Domínguez and Ullmann 1996;Cheesman et al 2003;García Ubaque et al 2007;Chiang et al 2008;Lafhaj et al 2008).…”