Ing De Materiales

Environ Geol (2007) 53:159–175 DOI 10.1007/s00254-006-0631-4

O R I G I N A L A RT I C L E

Sulfur based hazardous waste solidification
Abdel-Mohsen O. Mohamed Æ Maisa El Gamal

Received: 7 September 2006 / Accepted: 18 October 2006 / Published online: 24 January 2007 Ó Springer-Verlag 2007

Abstract Existing uses for sulfur are relatively advanced and offer limited opportunities toconsume significant new supplies. Currently, sulfur is in net surplus on a global basis, and with environmental regulations, greater sulfur recovery from petroleum and gas processing is mandated. The outlook is clear: there will be substantial and growing surpluses in global sulfur supply in the foreseeable future. Sulfur prices are likely to be under pressure, and producers could face substantial andgrowing disposal fees. Therefore, new markets must be found for sulfur to avoid disposal crises. One potential new market is the production of sulfur-solidified concrete. This is a thermoplastic composite of mineral aggregates bound together with chemically modified sulfur. The product is more durable than Portland cement. There may be monetizeable benefits in reducing greenhouse gas emissions thatwould enhance the attraction of sulfur solidified cement applications. The main objective of this study is to evaluate experimentally the potential use of sulfur as a solidifying agent for hazardous waste. To achieve this objective, the study reviewed the sulfur concrete literature, analyzed locally produced sulfur, evaluated a number of sulfur polymer modifiers and physical stabilizing agents,designed a set of experiments and evaluated the produced product for its hydromechanical-chemical properties. The results indicated
A.-M. O. Mohamed (&) Department of Civil Engineering, UAE University, P.O. Box 17551, Al Ain, UAE e-mail: Mohamed.a@uaeu.ac.ae M. El Gamal Research Affairs, P.O. Box 17551, Al Ain, UAE

that the manufactured sulfur polymer cement is an excellent candidate for: wastemanagement practices such as solidification/stabilization of hazardous waste; barrier systems for landfilling of hazardous waste; and waste water treatment plants. Keywords Fly ash Á Sand Á Molten sulfur Á Modified sulfur Á Orthorhombic Á Monoclinic Á Compressive strength Á Temperature Á Structure Á Voids Á Density Á Mineral formation

Introduction In the last decades, the availability of sulfur hasconsiderably grown in many countries. This is mainly due to the current environmental restrictions regarding petroleum and gas refining processes, which limit the maximum quantity of sulfur present in the combustibles. Extremely large quantities of sulfur are thus obtained as a by-product of these processes, for example, in the United Arab Emirates (UAE), which is ranked as the world’s fourth largestproducer, natural gas reserves are of roughly 212.0 trillion cubic feet. The Abu Dhabi National Oil Company (ADNOC) has placed increasing emphasis on the development and uses of its natural gas resources to meet the growing demand for power generation, water desalination, petrochemical plants and enhanced oil recovery. Concurrently, an environmental priority has been given to recovering andprocessing the associated gas. The development of new applications for sulfur becomes fundamental. Sulfur concrete has a relatively simple composition and manufacture, and very interesting characteristics and properties. Sulfur concrete

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Environ Geol (2007) 53:159–175

construction materials are used in many specialized applications in industry and transportation. They are currentlyused primarily in areas where conventional materials like Portland cement concrete (PCC) failed, such as in acidic and saline chemical environments. Sulfur concrete research There is evidence of even earlier uses of sulfur, and both archeological sites and classic literature offer proofs of the knowledge and utilization of sulfur as a binder. Study on the use of surplus sulfur in the manufacture...