Determining controls on element concentrations in cement kiln dust leachate

Journal Article · Thu Dec 31 04:00:00 EST 1998 · Waste Management

DOI:https://doi.org/10.1016/S0956-053X(98)00078-6· OSTI ID:323766

Duchesne, J ^[1]; Reardon, E J ^[2]

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1. Univ. Laval, Quebec (Canada). Dept. de Geologie et de Genie Geologique
2. Univ. of Waterloo, Ontario (Canada). Dept. of Earth Sciences

Cement kiln dust is a waste residue composed chiefly of oxidized, anhydrous, micron-sized particles generated as a by-product of the manufacture of Portland cement. When cement kiln dust is brought into contact with water, high concentrations of potassium, sulfate and caustic alkalinity are leached. Other constitutents are leached to a lesser extent. The objective of this study was to determine whether the concentration of a given chemical constituent in kiln dust leachate is controlled by the precipitation of a secondary mineral phase or whether its concentration depends on its initial availability to the leachate solution and its subsequent diffusive flux from hydrating particles with time. Differentiating between these two distinctive styles of leaching behavior is necessary to predict the chemical composition of kiln dust leachate under dynamic flow conditions in disposal environments. Evidence of solubility control was found for Si, Ca, Mg, Al, Zn, Ti, Sr, and Ba. The concentrations of Na, Cl, K, Mo, Cr and Se, however, were found to have no solubility control. Because of the observed lack of solubility control and the particularly high concentrations of Cr and Mo in kiln dust leachate, The authors tested two additives to reduce their concentrations: (1) aluminum oxide to promote the precipitation of calcium aluminosulfates and the proxying of chromate and molybdate for sulfate in their structures; and (2) iron metal to promote the reduction of chromate and molybdate to lower valent and less soluble forms. Neither treatment had any effect on the concentration levels of Cr and Mo in solution.

• OSTI ID: 323766
• Journal Information: Waste Management, Journal Name: Waste Management Journal Issue: 5 Vol. 18; ISSN WAMAE2; ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ALUMINIUM
BARIUM
CALCIUM
CHLORIDES
CHROMIUM
ECOLOGICAL CONCENTRATION
INDUSTRIAL WASTES
KILNS
LEACHATES
MAGNESIUM
MOLYBDENUM
PORTLAND CEMENT
POTASSIUM
SELENIUM
SILICON
SODIUM
STRONTIUM
TITANIUM
ZINC