Pilot trial of detoxification of chromium slag in cyclone furnace and production of slag wool fibres.

The pilot trial of detoxification of chromium slag in cyclone furnace and production of slag wool fibres were investigated in a power plant in China. 10-30 wt.% chromium slag was mixed with pulverized coal and 0-10 wt.% limestone as the raw materials of the cyclone furnace. Cr(VI) in chromium slag was reduced to Cr2O3 inside the cyclone furnace at high temperature. The melt was then produced into slag wool fibres through high-speed centrifugation. Optimal fibres with shot content of 4.5%, average diameter of 4.8 µm and acidity coefficient of 1.6 were produced with 15 wt.% chromium slag and 5 wt.% limestone in the mixture. Leaching toxicity test showed Cr(VI) of 0.016 mg/L of the produced fibres, which is far below the national standard of China. The total energy consumption could be significantly decreased compared to traditional cupola furnace method. This technique provides an effective and comprehensive technique for the detoxification and utilization of chromium slag at low cost and large-scale.