A Sustainable Process for the Resource Utilization and Stabilization Disposal of Stainless Steel Pickling Sludge

The resource utilization and stabilization disposal of stainless steel pickling sludge has received more and more attention from domestic and foreign scholars. Here, a sustainable treatment process of low-silica reduction smelting for stainless steel pickling sludge, followed by low-temperature vitrification for the reduced slag, has been proposed. The metal yield can reach more than 98% and metal content in the slag is lower than 0.6% under the optimal conditions of 1400 C temperature, 15% coal ratio, 10% SiO2 addition, and 1.5 h reaction time. The distinguishable crystal phase in the alloy mainly contained FeNi intermetallic compounds. The reduced slag mainly consisted of fluorite, anorthite, and magnesium silicate. The vitrification experiments implied that it was conducive to increase the vitreous body content of reduced slag via lowering the temperature. The vitreous body content of vitrification products can reach more than 85% when the SiO2 addition is in the range of 10-20% at 1250 degrees C. This work puts forward a new perspective to achieve both the recovery of valuable metals and the reduction of the slag amount.