In a sesame processing line, the Air-Screen Gravity Separator serves as the core equipment for both preliminary cleaning and fine sorting. Integrating air separation, vibrating sieving, and gravity separation into a single unit, it simultaneously removes light impurities, oversized and undersized debris, heavy impurities, and shriveled grains, thereby providing high-purity material for subsequent color sorting and destoning processes.
I. Core Functions (Four Key Capabilities)
Air Separation: Removal of Light Impurities (Dust, Straw, Leaf Fragments)
Utilizing differences in airflow suspension velocities, a negative-pressure air separation system carries away light impurities—such as dust, straw fragments, empty hulls, and weed seeds—which are then discharged through a dust collector. The cleaned sesame grains proceed into the sieving section, thereby reducing the processing load on downstream equipment.
Vibrating Sieving: Removal of Oversized and Undersized Impurities (Size Grading)
A multi-layer vibrating screen (typically comprising 2–3 layers) precisely sorts the sesame grains based on their particle size:
Upper Layer (Large Mesh): Removes large impurities such as soil clods, pebbles, and large straw fragments;
Middle Layer (Standard Mesh): Retains intact sesame grains while allowing broken grains, fine soil, and small impurities to pass through;
Lower Layer (Fine Mesh): Retains the qualified, standard-sized sesame grains while discharging minute impurities.
Gravity Separation: Removal of Heavy Impurities and Shriveled Grains (Density Stratification)
Through the combined action of screen bed vibration and airflow, the sesame grains are stratified according to their specific gravity:
Heavy Impurities (Pebbles, Soil Clods, Metal Shavings): Sink to the bottom and are discharged through the heavy impurity outlet;
Plump, Healthy Sesame Grains: Settle in the middle layer and flow toward the product discharge end;
Shriveled, Insect-Damaged, or Moldy Grains: Float to the top layer and are discharged along with the light impurities.
Pre-grading and Quality Enhancement (Material Uniformity)
The process yields clean, plump, and uniformly sized sesame grains, with the impurity rate reduced to below 0.5%. This provides a stable, high-quality raw material supply for subsequent processes—such as color sorting and polishing—thereby elevating the grade and market value of the finished product.
Working Principles of the Dedicated Sesame Air-Screen Gravity Separator
The machine integrates three major principles—air separation, multi-layer vibrating screening, and gravity stratification—to operate simultaneously. It achieves separation by leveraging three distinct physical differences in the material: volume size, weight density, and suspension velocity.
1. Air Separation Principle
The equipment features built-in, adjustable negative-pressure fans positioned at the front and rear, creating a longitudinal convective airflow field.
Light impurities (dust, broken stalks, empty hulls, grass clippings) have a low suspension velocity; they are drawn upward by the airflow, channeled into the dust collection system, and subsequently discharged.
Plump sesame seeds have a high suspension velocity; they remain unaffected by the airflow, sinking steadily into the screening unit to achieve a preliminary separation between light and heavy materials.
2. Multi-Layer Vibrating Screening Principle
The entire machine undergoes high-frequency, reciprocating linear vibration, causing the material to move forward at a uniform speed across the screen surfaces.
Grading and impurity removal are achieved based on the mesh aperture sizes:
Upper Layer (Large-Mesh Screen): Retains large clumps of soil and coarse stalks, discharging them through the impurity outlet.
Middle Layer (Standard Screen): Retains qualified, whole sesame seeds while allowing fine soil, broken seeds, and minute impurities to pass through.
Through mechanical vibration, impurities that do not meet the required size specifications are thoroughly screened out.
3. Gravity Stratification Principle (Core Mechanism)
Once the material falls onto the inclined gravity separation deck, it is subjected to the dual action of vibration and lateral airflow:
High Density: Stones, soil clumps, and heavy sand remain in close contact with the screen surface and are discharged toward the lower end of the deck.
Medium Density: Plump, high-quality sesame seeds flow along the central path, heading toward the finished product outlet.
Low Density: Shriveled seeds, insect-damaged seeds, and moldy sesame seeds are lifted and suspended by the airflow, separating out through the reject outlet.
Integrated Process Flow
Raw Material Feeding → Airflow removes light impurities → Vibrating screens eliminate oversized and undersized impurities → Gravity table stratifies and separates based on density → Separates the material into four distinct streams—clean sesame seeds, heavy stones, shriveled seeds, and various other impurities—completing the entire cleaning and purification process in a single pass.
II. Position and Value within the Production Line
Position: Located at the front end of the production line (following primary cleaning but prior to color sorting and destoning), it receives material from the primary cleaning screen, serving as a critical transitional node that bridges the preceding and subsequent stages.
Value:
Simultaneously removes five categories of impurities—light, heavy, oversized, undersized, and defective grains—thereby simplifying the process and reducing the total number of required machines;
Significantly reduces the operational load on downstream color sorters and destoners, minimizing material loss and boosting overall efficiency;
Features an integrated dust removal system to control airborne dust and improve the working environment within the facility.
III. Key Configuration Highlights
Sieves: Upper layer 8–10 mm; middle layer 2.5–3 mm; lower layer 2–2.2 mm (calibrated to match the specific grain size of sesame seeds);
Fan System: Utilizes negative-pressure air separation with adjustable airflow speed, ensuring thorough removal of light impurities without inadvertently carrying away sound product;
Gravity Separator: Features adjustable vibration frequency and deck inclination, allowing for optimal adaptation to sesame seeds with varying moisture levels and impurity concentrations.
Post time: May-20-2026
