A continuous adsorption study in a fixed-bed column was carried out using granulated slag (GS) as an adsorbent for the removal of methylene blue (MB) from aqueous solution. The effects of various parameters, such as initial dye concentration, flow rate, bed depth, and pH were investigated. Obtained results confirmed that the breakthrough time and exhaustion time were dependent on these factors. The adsorption capacity of GS was calculated at the 50% breakthrough point for different conditions. The highest breakthrough capacity (q,exp = 0.296 mg.g–1) was obtained with a 15 cm bed height and a 2 mL.min–1 rate by using a 10 mg.L–1 initial MB concentration at pH 7.5. Bohart–Adams, Bed Depth Service Time (BDST), and Thomas models were applied to experimental data to determine the characteristic parameters of the column. The Thomas model was found suitable for the description of the whole breakthrough curve, while the Bohart–Adams model was only used to predict the initial part of the dynamic process. The data were in good agreement with the BDST model. Thus, the granulated slag can be used as an adsorbent in the treatment of wastewater. Desorption was carried out with a deionized water as the desorbing agent, and reuse study was investigated.