Design and optimization of a shearing grinding device for efficient separation of eggshell and eggshell membrane

Global poultry egg production reached 100 million tonnes in 2024, and eggshell membranes account for approximately 10% of total egg mass. Mass egg consumption produces enormous amounts of waste eggshell. Eggshell is a natural calcium source, while eggshell membrane contains abundant proteins; both can be further processed into high value-added products. Current eggshell-membrane separation technologies commonly suffer from high energy input, chemical pollution or low separation efficiency, restricting large-scale industrial application. To address this bottleneck, this work adopts a combined shearing-grinding crushing strategy, which makes full use of the brittle nature of eggshell and high toughness of eggshell membrane. Key components of a custom shearing-grinding separation device were innovatively designed for this process. A four-factor three-level Box-Behnken response surface methodology (RSM) was implemented, with eggshell membrane separation rate selected as the response indicator for parameter optimization. The RSM-BBD regression model exhibited acceptable fitting performance (adjusted R² = 0.8637, predicted R² = 0.6983, Adequate Precision = 12.729). Under optimized operating conditions (15% moisture content, motor speed of 1,000 r/min, feed mass of 51 g, rotor-stator gap of 1 mm), a maximum separation rate of 87.28% was achieved. The proposed shearing-grinding device features simple structure, low energy consumption and environmental compatibility. This study offers a feasible technical route for the efficient industrial separation of waste eggshell and eggshell membrane, and supports the high-value valorization of poultry biomass waste within a circular economy framework.