The working principle of the proportion machine

The gravity separator (also known as a specific gravity separator or density separator) is a mechanical device that achieves separation based on the density differences of materials, widely used in agriculture, mining, and other fields. Its core principle is to separate mixtures with different densities through physical means. The following provides a detailed analysis from the aspects of working principle, structural composition, application scenarios, and technical advantages.

1. Operating principle: Coordinated action of density difference and external force

The sorting process of a gravity separator relies on the interaction between material density and the medium (such as air, water, or heavy liquid), and mainly consists of the following steps:

Material stratification

After the mixed material enters the sorting area, under the influence of external forces such as vibration, airflow, or water flow, components with higher density will settle downward due to gravity, while components with lower density will float upward, resulting in stratification. For instance, in grain sorting, plump grains have a higher density and sink faster; whereas moldy or empty-husked grains, due to their lower density, are easily lifted by the airflow.

Medium-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: Utilizing water flow or heavy liquid (such as zinc chloride solution), materials with a density less than the medium float on the surface, while those with a density greater than the medium sink to the bottom. It is commonly used for separating metals from plastics.

Mechanical separation and collection

The stratified materials are exported separately through screens, baffles, or spiral conveyors to achieve sorting. For example, the mine gravity separator tilts the vibrating screen surface, allowing high-density ores to slide down the screen surface while low-density gangue is discharged through the screen holes.

II. Core Structure and Functional Modules

Feeding system

Uniform feeding is crucial for sorting efficiency, and vibrating feeders or belt conveyors are commonly used to ensure that materials enter the sorting area continuously and stably.

Sorting device

Vibrating screen surface: High-frequency vibration is generated through motor drive to facilitate material stratification.

Airflow system (dry type): The fan generates a controllable airflow to separate lightweight impurities.

Water tank or heavy liquid tank (wet type): Provides buoyancy medium for separating materials with small density differences.

Control system

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