Abstract: In order to reduce the hazardous characteristics of tungsten slag from the manufacturing of ammonium paratungstate and to minimize the ecological environment pollution risk in the process of disposal and utilization, vitrification, considered as a promising technology for the management of hazardous wastes, is adopted to dispose the hazardous wastes for tungsten slag, which achieves the goals of reduction, innocent treatment and resource utilization. This study focused on the utilization of tungsten slag. Various proportions of diatomite, quicklime and aluminum oxide were adjusted to control the alkalinity of raw material, and the different melting temperatures as well as the holding times were set to prepare the glassy product. The results show that the main heavy metals in tungsten slag were Mn, As, Pb, Hg, Cr, Cu and Zn. By means of an appropriate technique (temperature:1 500℃, holding time:1.0 h, alkalinity:0.15-0.46), a vitrified product characterized with dense homogenous structure, low porosity and smooth appearance can be made. Compared with HJ/T 299-2007 and HJ/T 300-2007, the toxic substances in the finished samples were much lower than that of the limited value in GB 5085.3-2007 and GB 16889-2008, respectively. Furthermore, the vitrified product had excellent mechanical properties (robustness value:1.08%-3.47%, crushing value:2.47%-10.05%), which were much lower than that of the limited value in Standard for JGJ 52-2006. Therefore, this vitrified product is qualified as an alternative impermeable material for landfill use since it has excellent impermeability and permeability coefficients ranged from 1×10^-8-1×10^-9 cm·s^-1. The results also show that after being disposed by the vitrification technology, the heavy metal leaching toxicity and the hazardous characteristics of vitrified samples were significantly reduced to satisfy the harmless disposal. The physical chemistry properties and anti-seepage effect of vitreous met the performance requirements of potential applications such as the concrete sand and the alternative impermeable material.

Key words: hazardous wastes, tungsten slag, vitrification, solidification, leaching toxicity