Mineral particles are acted upon by two forces as they settle in a medium: the gravity of the particle in the medium (which is constant for a given particle in a given medium) and the resistance of the medium, which is related to the settling velocity of the particle. In the initial stage of settling, because the resistance of the medium is very small, the particles settle with acceleration under the influence of gravity. As the settling velocity increases, the resistance of the medium also increases, and the settling acceleration of the particles gradually decreases. After a certain period of time, the acceleration decreases to zero. At this point, the particles settle at a certain velocity, called the terminal settling velocity. The terminal settling velocity is affected by several important factors, including the density, particle size, and shape of the mineral particles, as well as the density and viscosity of the medium.