The working principle of the specific gravity machine

Gravity sorter (also known as gravity sorter or specific gravity sorter) is a mechanical equipment that separates materials based on their density differences, and is widely used in fields such as agriculture and mining. The core principle is to separate mixtures of different densities through physical means. The following provides a detailed analysis of the working principle, structural composition, application scenarios, and technological advantages.

1、 Working principle: synergistic effect of density difference and external force

The sorting process of a specific gravity machine depends on the interaction between the material density and the medium (such as air, water, or heavy liquid), and is mainly divided into the following steps:

Material layering

After the mixed materials enter the sorting area, under external forces such as vibration, airflow, or water flow, the components with higher density settle downwards due to gravity, while the components with lower density float upwards, forming layers. For example, in grain sorting, plump grains have high density and fast sinking speed; However, moldy or hollow grains are easily carried up by air currents due to their low density.

Media assisted separation

Dry sorting: Using air as the medium, by adjusting the wind speed and vibration frequency, light impurities (such as straw and dust) are blown away by the airflow, while heavy materials (such as ore and seeds) are retained.

Wet sorting: Using water flow or heavy liquid (such as zinc chloride solution), materials with a density lower than the medium float on the surface, while those with a density greater than the medium sink to the bottom. Commonly used for the separation of metals and plastics.

Mechanical separation and collection

The layered materials are exported separately through sieves, baffles, or spiral conveyors to achieve sorting. For example, the mining specific gravity machine tilts the vibrating screen surface to make high-density ore slide down along the screen surface, while low-density gangue is discharged from the screen holes.

2、 Core structure and functional modules

Feeding system

Uniform feeding is the key to sorting efficiency, and vibration feeders or belt conveyors are usually used to ensure that materials enter the sorting area continuously and stably.

Sorting device

Vibration screen surface: High frequency vibration is generated by motor drive to promote material stratification.

Airflow system (dry): The fan generates controllable airflow to separate light impurities.

Water tank or heavy liquid tank (wet type): provides buoyancy medium to separate materials with small density differences.

control system

Modern density machines are equipped with PLCs or frequency converters, which can adjust vibration amplitude, wind speed, or medium concentration to meet the sorting needs of different materials.