Recycling Nonmagnetic Material from De-sulferization Slag as Coarse Aggregate through Cold-Pressing Technique

Abstract

Every year there was approximately 500,000 tons of de-sulferization slag generated in Taiwan, but the recycling amount was very slightly. A new approach, the cold-pressing technique that incorporates the principles of the cement chemistry and composite material was developed to recycle innocuous resources (e.g. construction residual soil, granite and lime sludge, and sediment, etc.) as recycling coarse aggregate. Even this technique also has successfully been applied to recycle stainless steel reductive slag with low volume stability. This paper aims to show that using cold-pressing technique can recycle nonmagnetic material from de-sulferization slag as coarse aggregate. Herein the cement-based composite is regarded as concrete. Particularly, the mixture proportions with a low cement amount of 100 kg/m³ and more than 70% (by weight) of nonmagnetic material from de-sulferization were designed. The test results show that the specific gravity of recycling coarse aggregate is about 1.67 in the OD state; the absorption capacity is 27.65%; the dry loose density (i.e. unit weight) is about 1,106 kg/m³; and other characteristics conform to ASTM C33. Therefore the cold-pressing technique is a new and practicable approach to recycle nonmagnetic material from de-sulferization slag in future.