Waste printed circuit board (WPCBs) is a kind of sustainable resource for providing economically valuable metals due to its huge output and excellent metal grade. Gravity separation is an effective pre-concentration technology to separate WPCBs particles with significant density difference. This study focuses on revealing the mechanism of gravity concentration from the perspective of dynamics and statics. The settling velocity of three kinds of particles in WPCBs (organic matter, glass fiber and metal particles) are calculated, which can be expressed by traditional settlement velocity model with correction coefficient. Subsequently, the equal-sedimentation model of the particles was established, and the calculation results show that the particle size ratio should be within 5.58. The lowest potential energy model was proposed to explain the stratification process of particles from the static point of view. The potential energy calculation results show that the stratification process dominated by density difference is spontaneous, which can achieve the lowest potential energy. Shaking table test shows that the metal particles with different sizes can be effectively enriched in the concentrates, and the metal grade increases with the decrease of particle size, from 56.5% to 68.2%, and the metal recovery decreases from 86.41% to 83.04%.

废印刷电路板（WPCB）由于其产量高和金属品位高而成为提供经济上有价值的金属的一种可持续资源。重力分离是一种有效的预浓缩技术，用于分离密度差异显着的WPCBs颗粒。这项研究的重点是从动力学和静力学的角度揭示重力集中的机理。计算了WPCB中三种颗粒（有机物，玻璃纤维和金属颗粒）的沉降速度，可以用具有校正系数的传统沉降速度模型来表示。随后，建立了颗粒的均沉模型，计算结果表明粒径比应在5.58以内。提出了最低势能模型，从静态的角度解释了粒子的分层过程。势能计算结果表明，以密度差为主的分层过程是自发的，可以实现最低的势能。振动台试验表明，不同尺寸的金属颗粒可有效富集到精矿中，金属品位随颗粒尺寸的减小而增加，从56.5％降至68.2％，金属回收率从86.41％降低至83.04％。