Selective separation and recovery of selenium from copper anode slime by compound leaching followed by sulfate roasting

•Selective separation and recovery of Se from copper anode slime can be achieved.•Se was effectively enriched by approximately 200% after first compound leaching.•More than 99.39 % of Se was separated by using sulfate roasting, whereas the extraction of the remaining metals in were all less than 0.5 %.•The evaporative separation process of Seis controlled by intraparticle Diffusion Control.