A Facil Water Treatment Rendering Cement Kiln Dust Reusable in Clinker Manufacturing

Cement kiln dust (denoted CKD) is by-produced during the calcination process in the kiln of cement clinker manufacturing plants [1,2]. It is a massive by-product (ca. 30 million tons/year worldwide and 5-20 % of the amount of cement clinker produced [3-5]) that is generally a heterogeneous mixture by chemistry and particulate size. These characteristics are dependent on the raw feed materials, fuels, kiln pyroprocessing type (dry or wet), overall equipment layout, and kind of cement being manufactured [4,6]. Chemically speaking, however, it includes oxides, carbonates, chlorides and sulfates of Ca, K, Na, Al, Fe and Si, with CaO/CaCO3 being its major constituent [2]. CKD is separated from the clinker kiln exhaust gas in order to prevent (i) the alkali content of the clinker from exceeding the maximum allowable value (≤0.6 %) [7], and (ii) the buildup of excessive salts (chlorides and sulfates) in the produced clinker [7].