From Wastes to Resources: Life Cycle Environmental Benefits from the Recycling of Blast Furnace Slag

摘要

Blast furnace (BF) slag from iron smelting process, has great potential for producing green building materials. The recycling-processes of BF slag were analyzed in this paper. Based on life cycle inventory (LCI) analysis and GaBi 4 software, resources consumption and greenhouse gas(GHG) emissions of slag portland cement and commercial concrete production processes using BF slag were analysed in a Chinese building materials factory. Accordingly, the environmental benefits from the recycling of BF slag were assessed in terms of energy saving, reduction of raw material consumption and mitigation of GHG emissions. The results show that, compared with ordinary portland cement, slag portland cement can save energy 1911MJ/t (decreased by 26%), reduce raw material consumption 1158kg/t (decreased by 27%) and mitigate GHG emissions 236kg/t (decreased by 26%). Meanwhile, the results for slag portland cement are 352MJ/t (decreased by 6%), 278kg/t (decreased by 8%) and 47kg/t (decreased by 7%), respectively, in contrast to composite portland cement. Likewise, commercial concrete (with slag powder) can save energy 97MJ/m3 (decreased by 5%), reduce raw material consumption 7kg/m3 (decreased by 0.3%) and mitigate GHG emissions 12kg/m3 (decreased by 5%), compared with common commercial concrete (without slag powder). Thus, the recycling of BF slag for slag portland cement and commercial concrete have obvious positive environmental benefits.