Process Analysis and Parameters Optimization of Black Soldier Fly Sand Mixture with Two-Stage Sieve Surface Vibration Separating Machine

The application of the conventional vibrating screen to the separation of the black soldier fly (BSF) sand mixture has several problems (e.g., high rate of impurity and low efficiency). A two-stage sieve surface vibratory sorting device with combined planar and curved surfaces was investigated, and its critical operating parameters were determined. Moreover, a coupling simulation model of the sieve surface and the larvae–sand mixture was built based on the characteristics of the BSF breeding process, and its critical operating parameters were optimized. Next, the Plackett–Burman test was set to determine the significant factors for the separation of two-stage sieve surface vibrations as amplitude and curved height. The process of crushing separation of frass aggregates and the process of collision transport of BSF larvae were studied through simulation, and the actual test stand was built for parameter verification tests. The preferred parameter combinations comprised 0.012 m amplitude and 0.007 m curved surface height at the impurity rate of 2.34% and the insect injury rate of 5.65%, as well as 0.013 m amplitude and 0.005 m curved surface height at the impurity rate of 3.15% and the insect injury rate of 4.3%, respectively, thus conforming to the requirement of separating BSF larvae–sand mixture to reduce the impurity and prevent larvae injury. The results of this study can lay a basis for the structural improvement and operational parameter adjustment of the BSF larvae–sand mixture separation device.