Investigated type and mixing ratio of binders for the stabilization/solidification of electric arc furnace slags and meeting the solidified standards promulgated by the Ministry of Industry No.1/B.E. 2531 and No.6/B.E. 2540. An estimate of 45,300 ton/year of slage were generated from electric arc furnaces producing steel rod. There were two types of electric arc furnace slags which were black and white slag. The black slag was generated from the purifying process and the white slag was generated from the refining process. According to the notification of the Ministry of Industry No.6 (B.E. 2540), electric arc furnace slag had been classified as specific sources hazardous wastes. The results of the solidification unveiled that portland cement was the most appropriate binder in terms of economical and the compressive strength compared to other binders, which were a mixture of portland cement and lime, a mixture of portland cement and sodium silicate, and a mixture of portland cement and lime and sodium silicate, of equal mixing ratios. It was also found that the optimum mixing ratios for the portland cement were 15 percent and the water/cement ratio were 0.7 for both black slag and white slag. The density and concentration of heavy metals in extractant also met the solidified standard promulgated by the Ministry of Industry. The estimated cost for the stabilization/solidification of the slags, included the solidification cost, the transportation cost and the cost for disposal in the secured landfill at Rajburi of the Ministry of Industry, were about 1,230 baht per ton of slags or equal to 73.80 baht per ton of steel rod or 0.75 percent of the price of steel rod.
