The work presented here investigates the optimum conditions for maximum recovery of iron from the waste slag. The most advantageous option for industrial trial is roasting of the waste slag under reducing condition followed by magnetic separation selected from various options for recovery of iron from the waste slag. The experimental results show that under the treatment condition in this work, about 70% of the iron was recovered from the waste slag, where the iron content in the concentrate is 57%. After further treatment with chlorinated segregation-magnetic separation, the iron content in the recovered slag can reach 83%. After the treatment, sulphur content in the concentrate was reduced significantly and gangue materials, such as SiO2, Al2O3, and TiO2, were reduced effectively. This paper is mainly focused on the results of reduction roasting- magnetic separation. Recovery of iron from the waste slag is of great interest for maximum use of mineral resource, reduction of environment impact, and improvement of economical benefits to the related companies.