In the present study, the strontium hexaferrite (SrFe12O19) has been successfully produced from recycled mill scale and strontium carbonate (SrCO3) powders with stoichiometric ratio (SrCO3/Fe2O3) of 1:6 by mechanochemical synthesis process, followed by annealing at 975 degrees C temperature. As the mechanochemical synthesis time increased, the phase ratio of hard magnetically SrFe12O19 in the structure increased after the annealing, according to the XRD analysis. The SrFe12O19 phase formation temperature decreased from 851 degrees C to 762 degrees C with increasing mechanochemical synthesis time. Also, FTIR analysis showed that The CO bond peaks are only visible for a 2 h synthesis time at 854 cm-1 wavenumbers. Magnetic properties have changed according to particle size, activation energy, and phase ratios. The best magnetic properties were obtained with the application of 16 h of synthesis time. The coercivity values of 3.3, 3.6, 4.6, 5.5, 5,4, and 3.7 kOe were obtained for 2, 4, 8, 16, 32, and 64 h of mechanochemical synthesis times, respectively. The residual magnetization density (Br) values under 1 T magnetic field for the same synthesis times were obtained as 168, 221, 292, 347, 314, 258 mT, respectively. (c) 2021 Elsevier B.V. All rights reserved.