Energy-saving production of high value-added foamed glass ceramic from blast furnace slag and hazardous wastes containing heavy metal ions

Abstract

In this work, foamed glass ceramic (FGC) is prepared by using blast furnace slag (BFS), waste glass, and zeolite adsorbing heavy metal ions (HMI) as the raw materials. To conserve energy, the residual heat of BFS at low-temperature could be used as a heat source. In order to simulate the heating process, the green body is directly put into a hot tube furnace and heated during the cooling process without heat preservation process. The optimized FGC has an apparent density of 0.81 g cm−3, a compressive strength of 4.51 MPa, and a water absorption of 19.5%. The physical property of high value-added FGC meets the industry standard and it could be widely used in the field of building materials. The leaching efficiencies of Cu2+, Zn2+, and Cd2+ of FGC are as low as 0.76 mg L−1, 0.55 mg L−1, and 0.79 mg L−1, respectively. The HMIs are steadily stabilized in the FGC and have less impact on the environment. It is found that the newly formed columnar crystal has a great contribution to the improvement of compressive strength due to its pinning effect between the glass phase and crystalline phase. The newly formed lamellar crystal plays an important role in preventing HMI from escaping out into the environment. This study provides a reasonable method for converting solid waste into high value-added product, recycling industrial tail heat at low-temperature zone, and eliminating the harm of hazardous waste containing HMI to the environment.