Article

The effect of foreign ions on the reactivity of the CaO–SiO 2 –Al 2 O 3 –Fe 2 O 3 system Part II: Cations

Cement and Concrete Research (Impact Factor: 3.85). 10/2001; 32(3):463-469.

ABSTRACT The subject of this paper is the effect of foreign cations on the reactivity of the CaO – SiO 2 – Al 2 O 3 –Fe 2 O 3 system. One reference mixture and eighteen modified mixtures, prepared by mixing the reference sample with 1% w/w of chemical grade MnO 2 , CuO, were studied. The effect on the reactivity is evaluated on the basis of the free lime content in samples sintered at 1200 and 1450 °C. At 1200 °C, the reactivity of the mixture is greatly increased in the presence of Cu and Li oxides. Based on their effect at 1450 °C, the added elements can be divided into three groups. W, Ta, Cu, Ti and Mo show the most positive effect, decreasing the free CaO (fCaO) content by 30 – 60%, compared with the pure sample. Cr and B cause an increase of fCaO content, while the rest of the elements exhibit a marginal positive effect. According to their volatility at 1450 °C, the added compounds can be subdivided into three groups of low (Ti 4 + , Cu 2 + , Mo 6 + , W + 6 , V 5 + , Zn 2 + , Zr 4 +), moderate (Cr 6 + , Co 3 + , Ni 2 + , Mn 4 +) and high volatility (Cd 2 + , Pb 2 +). All burned samples, analyzed by means of X-ray diffraction, have a final mineralogical composition, which corresponds to the structure of a typical clinker. D

Download full-text

Full-text

Available from: Konstantinos G. Kolovos, Jul 06, 2015
3 Followers
 · 
183 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Lime drying is an effective technique to achieve the volume reduction of sewage sludge produced by wastewater treatment plants. It holds the advantages featuring most cost-effective, practical operation with high dryness fraction and good stability. However, the great challenge facing environmental engineering is to solve the outlet for lime-dried sludge (LDS). Since calcium in LDS is a potential raw material for producing cement, the feasibility of combining LDS disposal with cement kiln and the influence on sintering of cement were investigated in this work. The results indicated that adding LDS (<15 wt %) improved the burnability of clinker leading to reduce the temperatures for calcium carbonate (CaCO3) decomposition and liquid phase formation. Furthermore, the presence of phosphorus and other trace elements increased the amount of liquid phase and decreased the viscosity, making it favorable for forming tricalcium silicate (C3S) in cement clinker. The free lime content in the clinkers was below 1.0%; thus, meeting the standard of Chinese current regulatory thresholds of 1.5%. Compressive strength of the clinkers produced with different amount of sludge at 3, 7, and 28 d met cement production standards (GB/T17671–1999). Moreover, when LDS was substituted, it not only provided chemical components but also contributed 2441 J/g of LDS with moisture content less than 50% in cement producing kilns. Overall, this work could effectively achieve the sludge treatment target of environmental protection, solid reduction, and resources utilization.
    Journal of Cleaner Production 08/2014; 83:286–293. DOI:10.1016/j.jclepro.2014.07.070 · 3.84 Impact Factor
  • Source
    Materiales de Construcción 12/2008; 58(292). DOI:10.3989/mc.2008.45307 · 0.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a laboratory scale simulation that aims to investigate the possibility of partially substituting ordinary cement raw mix with waste ammunition materials (WAM), originated from a shooting range in Athens, Greece, in Portland cement clinker produc-tion. One reference and twelve modified mixtures, containing 0.5%, 1.0%, 1.5% and 2.0% w/w of three blends of corresponding types of waste ammunition materials, were examined. It was concluded that the three used WAM blends, improve remarkably the burnability of the cement raw mixture, even though in a different extent, without affecting considerably the hydration rate and the cement properties. In spite of the high volatile matter in the WAM, primarily due to high levels of lead present, incorporation degree of the heavy metals pres-ent in the WAM blends in the mineralogical clinker compounds was rather high during the sintering process. Leaching tests showed that the heavy metal concentrations in the leachates were kept low.
    Cement and Concrete Composites 12/2005; 28(2):133-143. DOI:10.1016/j.cemconcomp.2005.10.001 · 2.76 Impact Factor