Leachable Characteristics of Arsenical Borogypsum Wastes and Their Potential Use in Cement Production

• Published in: Environmental science & technology 2009-09, Vol.43 (18), p.6939-6943
• Main Authors: Alp, İbrahi̇m, Deveci̇, Haci, Süngün, Y. Hali̇l, Yazici, Ersi̇n Y, Savaş, Mehmet, Demi̇rci̇, Songül
• Format: Article
• Language: English
• Subjects: Applied sciences; Arsenic; Arsenicals - analysis; Calcium Sulfate - analysis; Cement; Characterization of Natural and Affected Environments; Comparative analysis; Conservation of Natural Resources; Construction Materials - analysis; Exact sciences and technology; Hazardous Substances; Leaching; Mechanical Phenomena; Metals - analysis; Particle Size; Pollution; Time Factors; Waste materials; Waste Products - analysis; Water Pollutants, Chemical - analysis; X-Ray Diffraction
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es9013008

In this study; the potential use of arsenical borogypsum wastes (ABW) as a set retarder in cement industry was investigated. The comparative performances of arsenical borogypsum wastes (ABW) and natural gypsum samples (NG1 and NG2) at different proportions in the range of 3−8 wt % were tested based on compressive strength over 1, 2, 7, and 28 days and setting times. The use of ABW was observed to lead to a somewhat slower rate of development of strength of the mortar samples than those of NG1 and NG2 during the curing period of 7 days. This is the indication of the effectiveness of ABW as a set retarder. The 28-day compressive strength of mortars tended to decrease with the addition or increasing the proportion of ABW, beyond 5 wt % in particular. The data for setting times of the cement products confirmed set retarding characteristics of ABW with an initial setting time of 90−120 min at 3−5 wt % dosage, which conforms to the desired setting time of ⩾60 min for CEM I (42.5 N) type cement (TS EN 197−1). Leachability tests (TCLP and SPLP) have also shown that ABW can be classified as a nonhazardous waste; but it can readily release metals such as As and Mn, in particular, whereas the mortar samples containing ABW-cement clinker present no environmental concern with its remarkably reduced leachability.