Stabilization of a Chromium-Containing Solid Waste: Immobilization of Hexavalent Chromium

Abstract

This article describes the stabilization/solidification (S/S) of a steel industry waste, using a common type-F fly ash from a coal power station as the main binder. The waste, which contains hazardous levels of metals, may be stabilized by a conventional S/S to achieve permissible Pb, Cd, and Zn concentrations in the Toxicity Characteristic Leaching Procedure (TCLP) leachates of S/S solids. On the other hand, the stabilization of Cr(VI), also present in the waste, requires a reducing pretreatment stage with ferrous sulfate to attain TCLP leachates within limits. A bibliographic study on the stabilization of Cr(VI)-containing wastes is included in the paper, along with a discussion on the lowest Cr concentration in TCLP and aqueous (DIN) leachates.

Optimum Dose Of Lime And Fly Ash For Treatment Of Hexavalent Chromium–Contaminated Soil

“…The major conclusion, compared with the other research, is the fact that in no cases did class F fly ash improve performance when mixed with other binding agents, maybe due to it lower pH than class C fly ash or to the dosage in respect to the amount of Cr(VI). A review of the literature reveals some other important studies on the effective use of fly ash(lime for Cr(VI) immobilization in solid wastes (Albino et al, 1996;Rodríguez-Piñero et al, 1998). While other important research has been carried out using either cement or in addition to fly ash (Palomo and Palacios, 2003;Rinehart et al, 1997), these works focused on other applications of these agents for stabilization.…”

“…Generally speaking, immobilization treatment involves the use of inorganic binders, such as cement, fly ash, lime, slugs, or organic binders, as bitumen; among these various stabilizing agents investigated by numerous researchers, lime, fly ash and Portland cement are the most prominent (Catalan et al, 2002;Rodríguez-Piñero et al, 1998;Evanko and Dzombak, 1997).…”

“…A Portland cement particle is a heterogeneous substance containing reactive calcium, silica and alumina compounds that interact with the water in the soil producing hydrated calcium silicates, hydrated calcium aluminates and hydrated lime (Ca(OH) 2 ). This process is often called "pozzolanic reaction" and occurs over a long period of time, such as months or even years (Rodríguez-Piñero et al, 1998;Ç okça, 2001) and depend also on the reaction conditions, e.g., quantity and type of Portland cement, soil characteristics, temperature (Dermatas and Meng, 2003). The formation of these calcium alumino-silicate hydrates is mainly responsible for heavy metal immobilization through surface sorption, inclusion and physically entrapment (Dermatas and Meng, 2003).…”

The enhancement effect of pre-reduction using zero-valent iron on the solidification of chromite ore processing residue by blast furnace slag and calcium hydroxide

“…Several remediation technologies have already been applied in the treatment of Cr(VI) in COPR (Rodríguez-Piñero et al, 1998;Wang et al, 2007;Velasco et al, 2012). One promising technology is the stabilization/solidification (S/S) (Dermatas and Meng, 2003;Dalmacija et al, 2011) of solid wastes by mixing the waste with a binder to reduce the leachability of the contaminants and to convert the hazardous waste into an environmentally acceptable form of waste for land disposal or as recyclable construction material.…”

Comparison of mechanical and leaching behaviours of pulverised fuel ash/low-grade magnesium oxide-cement blended stabilised/solidified baghouse dust

“…The right choice and effective use of binders in S/S is important since they physically and chemically trap contaminants. Portland cement and lime have been widely used as primary binders while ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA), natural pozzolans, low grade magnesium oxide and silica fume are widely used as secondary binders (Alsheyab & Khedaywi, 2013;Arribas, Santamaría, Ruiz, Ortega-López, & Manso, 2015;Chang, Lin, Ko, & Liaw,1999;Chen, Tyrer, Hills, Yang, & Carey, 2009;del Valle-Zermeño, Giro-Paloma, Formosa, & Chimenos, 2015;Fernandez, Macias, Guerreo, Lorenzo, & Goni, 2000;Gervais & Ouki, 2000, 2002, Lampris, Stegemann, & Cheeseman, 2008, 2009a, 2009bParia & Yuet, 2006;Pasetto & Baldo, 2010;Poon, Lio, & Tang, 2001; Rodrfguez-Piñero, Pereira, de Elvira Francoy, & Vale Parapar, 1998;Salihoglu & Pinarli, 2008;Serjun et al, 2015;Shi & Spence, 2004;Stegemann & Zhou, 2009).…”