2. Ground space: silos, hoppers, ore chutes, single-roll crushers, single-roll chutes, cold screens, mixers and cooling towers.
3. Underground space: circulating pool, primary desulfurization sedimentation tank, pump pit, underground pipeline, pit, sewage pool (well), cable trench, sewer, etc.
4. When working in a confined space, the examination and approval procedures must be performed in strict accordance with the Application and Approval Form for Working in a Confined Space. Confined space operations should be controlled and managed according to the classification of hazardous operations, and the examination and approval procedures should be strictly implemented.