Research on separation mechanism of waste palladium catalyst in a structure-optimized compound dry separator based on DEM-CFD

Abstract

Recovery of precious metals from waste catalysts is necessary. The compound dry separator provides a new method for the recycling of waste catalysts with special morphology. The bed surface structure was modified in consideration of the unique properties of spent palladium catalyst in petrochemical industry. The solid-fluid coupling method (DEM-CFD) was used to study the distribution of airflow on the bed surface and the motion characteristics of particle swarm with different combinations of properties. The results showed that the best size of the apertures of bed surface was 2 mm and the optimum installation angle (β) of the lattice bars on bed surface was 50°. The velocity of air flow was small in the backplane region, but relatively large in the region far away from the backplane. And so was the case with dynamic pressure. The dynamic pressure was the largest in the central wind apertures and decreased gradually along the upward direction. The key factor influencing the distribution and movement of the aggregate on the bed surface was the shape of particles, while the effect of density was relatively weak. The separation efficiency (E_f) in numerical simulation was 99.83%, which coincided with the actual experimental result (99.57%).

Keywords:

• Compound dry separator
• particle motion
• waste palladium catalyst
• DEM-CFD
• flow field

Funding

The research work is financially supported by the Natural Science Foundation of Jiangsu Province [BK20160055], the Found of State Key Laboratory of Mineral Processing [No. BGRIMM-KJSKL-2017-10], the National Natural Science Foundation of China [No.U1508210], the Priority Academic Program Development of Jiangsu Higher Education Institutions.