Abstract:
In order to reduce the hazardous characteristics of chromium dust generated in the production of stainless steel, and reduce the ecological environment pollution risk in the process of disposal and utilization, advanced vitrification technology is adopted to treat chromium dust hazardous waste. Vitrification is considered as a promising technology for management of hazardous waste, and it achieves the goals of reduction, innocent treatment and resource utilization. This study focused on the utilization of the chromium dust from the manufacture of stainless steel. Various proportions of diatomite, bentonite, quicklime and aluminum oxide were adjusted to control the alkalinity of the raw materials, and different melting temperatures as well holding times were set to prepare glassy products. The results showed that the main heavy metals in the chromium dust were Cr and Ni. By means of an appropriate technique (temperature, 1450 ℃; holding time, 0.5 h; alkalinity, 0.14-0.55), a vitrified product characterized with dense and homogenous structure, low porosity and smooth appearance could be made. Compared with
Solid Waste-Extraction Procedure for Leaching Toxicity-Sulphuric Acid & Nitric Acid Method (HJ/T 299-2007) and
Solid Waste-Extraction Procedure for Leaching Toxicity-Acetic Acid Buffer Solution Method (HJ/T 300-2007), the toxic substances in the finished samples were lower than the limits of
Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity (GB 5085.3-2007) and
Standard for Pollution Control on the Landfill Site of Municipal Solid Waste (GB 16889-2008), respectively. Furthermore, the vitrified product had excellent physical and mechanical properties (robustness value, 1.1%-4.5%; crushing value, 3.4%-7.5%), which was lower than the limits in
Standard for Technical Requirements and Test Method of Sand and Crushed Stone (or Gravel) for Ordinary Concrete (JGJ 52-2006). Therefore, this vitrified product could be used as an alternative impermeable material for landfills since it has excellent impermeability, and the permeability coefficients ranged from 10
-9-10
-8 cm/s. The research showed that after the vitrification treatment, the heavy metal leaching toxicity and hazardous characteristics of the vitrified samples are significantly reduced, which can achieve harmless disposal. The physical chemistry properties and anti-seepage effect of the vitrified material meet the requirements of potential application scenarios such as concrete sand and alternative impermeable materials.