الفهرس | Only 14 pages are availabe for public view |
Abstract Cement kiln dust (CKD) is a solid waste material that is produced in massive quantities, ca. 30 million tons per year worldwide. In Egypt, more than one million tons of CKD have been produced annually. Unfortunately, large amounts of it are land-filled or stockpiled. Hence, CKD is, hitherto, neither properly disposed, nor adequately utilized. Accordingly, any research endeavors towards opening up profitable applications that use up large amounts of the stockpiles of CKD worldwide, would, no doubt, be an added value for the cement industry and a sustainable means of environmental protection. Therefore, the present investigation was designed to join the forces with the current worldwide research interest in applications of CKD, however focusing on (i) alleviating obstacles facing the reusing of CKD in clinker manufacturing, and (ii) probing its surface reactivity in heterogeneous catalysis of acid-base and/or redox reactions. To accomplish these objectives, a representative sample of CKD, obtained from a local cement manufacturer (ASECMINYA/Minia Portland/El-Minia/Egypt), was fully characterized to reveal its chemical and phase compositions, thermal stability, particle morphology, surface area, and acid-base properties in aqueous suspension, using a range of physic-chemical analytical techniques; namely, X-ray fluorescence spectroscopy (XRF), X-ray powder diffractometry (XRD), Fourier-transform infrared spectroscopy (FTIR), nitrogen sorptiometry (SBET), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and pH-metry. Subsequently, portions of the CKD were subjected to (i) heat treatments at different high-temperatures (500-1000 °C), and (ii) water treatments for short and long periods. The consequences of these treatments were probed on the bulk and surface properties of the CKD using adequate analytical techniques. The surface reactivity of the CKD and its treatment products was explored in two functions: (i) the leachability of the CKD components at the solid/water interfaces established during the water treatment course, and (ii) the decomposing catalytic interactions at the solid/H2O2 interfaces established in the peroxide aqueous solutions, as well as the solid/2-Propanol (or solid/Methylbutynol) interfaces established in a surrounding gas phase of the alcohol molecules. The literature background and the methods and outputs of the research studies performed in the present investigation are presented in the thesis manuscript over four chapters. Chapter 1 sets out literature background information about the CKD status in the cement industry, as well as its current and prospective uses and applications. Chapter 2 details the materials, methods, and techniques used to characterize the CKD and the consequences of its heat and water treatments. This is besides the products of its catalytic interactions with H2O2 molecules in solution, and 2-propanol (or methylbutynol) molecules in the gas phase. Chapter 3 presents and discusses bulk and surface characterization results obtained for the CKD and the consequences of its heat and water treatments. Chapter 4 presents and discusses results communicated by the follow-up measurements and data processing for the catalytic activity of the CKD and its heat treatment products in the decomposition reactions of H2O2 molecules in solution and 2- propanol (or methylbutynol) molecules in the gas phase. |