Solidification of cement kiln dust using sulfur binder

• Published in: Journal of hazardous materials 2011-08, Vol.192 (2), p.576-584
• Main Authors: Mohamed, Abdel-Mohsen O., El Gamal, Maisa M.
• Format: Article
• Language: English
• Subjects: Alkali metals; Alkaline waste; anions; Applied sciences; aqueous solutions; Binder; cement; Cements; chemical composition; Chemical engineering; Chemical stability; construction industry; Construction Materials; cooling; Crystallization, leaching, miscellaneous separations; Durability; Exact sciences and technology; Fiber glass; General treatment and storage processes; glass fibers; Heavy metals; Hot Temperature; Hydrogen-Ion Concentration; industrial wastes; Kilns; Leachability; mechanical properties; metal ions; methodology; Microscopy, Electron, Scanning; Microstructure; mixing; natural gas; Natural water pollution; Other industrial wastes. Sewage sludge; petroleum; Pollution; Polymerization; Reduction; Sand; seawater; Seawaters, estuaries; sodium sulfide; Solidification; Strength; sulfates; Sulfur; Sulfur - chemistry; temperature; Wastes; Water treatment and pollution
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.05.057

► Sulfur is a potential candidate for binding cement kiln dust (CKD). Solidified CKD articles exhibit homogenous and compact internal microstructure with excellent mechanical properties. Inclusion of glass fiber increases the strength and reduces volume change. Addition of anhydrous sodium sulfide reduces heavy metal leachability from solidified articles. The present study aims to offer a new methodology for consuming two industrial wastes; sulfur, from petroleum and natural gas industries, and cement kiln dust (CKD), from Portland cement industries, in construction industry. Sulfur solidified cement kiln dust material (SSCKDM) was manufactured by mixing molten sulfur, treated sulfur, CKD and sand at a controlled temperature in excess of 120 °C. The hot mixture was subsequently cast and shaped into the desired mold and was then allowed to solidify at a specified cooling rate. Solidified materials were immersed for time periods up to 28 days in distilled water at different temperatures of 25 and 60 °C, sea water, and acidic and basic universal buffer solutions of pH4 and pH9, respectively. Solidified material performance as function of time and type of aqueous solution exposed to was evaluated in view of compressive strength variations and leachability of metal and heavy metal ions. The results indicated that the solidified articles exhibit homogenous and compact internal microstructure with excellent mechanical properties. However, it showed durability problem upon exposure to aqueous solution environments due to the initial chemical composition of the CKD, whose leached test showed release of relatively high amounts of sulfates and alkali metals. Durability of SSCKDM articles in relation to strength reduction and crack formations control was improved by addition of glass fiber while, the use of anti-leaching agent such as anhydrous sodium sulfide resulted in reduction of leached heavy metals without any measurable decrease in leached amounts of alkali metals and anions from the solidified matrix. Furthermore, based on leachability index method of calculation, potential chemical mobility of metal and heavy metal ions from the solidified matrix was characterized as medium.