The aim of the present study is to selectively extract antimony and arsenic from decopperization slime through alkaline sulfide hydrometallurgy with a view to recycle the obtained solid residue within the copper smelter, and also regenerate the sulfide lixiviant during the process. Rechtschaffner experimental design was used to evaluate the joint influence of several experimental parameters such as leaching temperature, Na₂S concentration, solid concentration, and reaction time on the extraction of antimony and arsenic from the material. The most active parameters influencing the extraction of the metals are solid concentration and reaction period. In addition, the results show that solid concentration interacted strongly with the leaching time and slightly with reaction temperature, which is an indication that solid concentration is the predominant influencing factor in removing antimony and arsenic from the material. It is also indicated from the results that about 95% Sb and 89% As were extracted when 50 g/L of the decopperization slime was dissolved in alkaline sulfide lixiviant containing 200 g/L Na₂S + 20 g/L NaOH at 60 °C for 24 h. Moreover, analysis of the leach residue reveals that copper sulfide and lead sulfide remain as the main constituents of the residue. The bismuth-containing mineral phase was not observed in the residue because of its low concentration, and also the Sb/As-bearing mineral phases were not detected due to the selectivity of the leaching reagent to the metals. Based on the experimental results from this investigation, a process flowsheet for the alkaline sulfide treatment of a decopperization slime was proposed with a view to eliminating its antimony and arsenic contents in a sustainable manner.