Abstract: In order to efficiently recover valuable elements from a sulfur thermal filter residue in Inner Mongolia，a systematic process mineralogy study is carried out on the problems of unclear material composi⁃ tion and occurrence state，complex mineral dissemination relationship and so on.The results show that the grade of S，Pb，Zn and Ag in the slag is 69.94%，4.10%，5.30% and 172.00 g/t，respectively，which are the main valuable elements for recovery.Among them，sulfur mainly exists in the form of elemental sulfur （80.02%），and 8.99% of sulfur occurs in sulfides of copper，lead，zinc and iron，which is a secondary source of recovery.The characteristics of mineral dissemination show that elemental sulfur is mostly wrapped in metal sulfide ore and closely associated with it，and a small part is adjacent structure. The particle size of elemental sulfur is relatively coarse（+75 μm accounts for 65.69%），while sulfides are mostly fine-ultrafine embedded. It is appropriate to use stage grinding-stage flotation process to enrich elemental sulfur and metal sulfides respectively.In addition，silver mainly occurs in lead minerals，and its direction should be consis⁃ tent with lead minerals. In view of the fact that copper，lead and zinc oxides account for 40%～70% of metal minerals and are different from the main gangue minerals（gypsum and anhydrite），the recovery of such met⁃ al oxides can be strengthened by gravity separation process.

Key words: sulfur thermal filter residue, process mineralogy, mineral composition, particle size