During the processing of grains (such as wheat, rice, and corn) and legumes (such as mung beans, soybeans, and red beans), raw materials often become contaminated with metal impurities such as nails, wire, iron filings, and nuts during harvesting, drying, and storage. These impurities can damage subsequent processing equipment (such as the gears and rollers of grinders and polishers) and may also affect the quality of the finished product and even pose a health risk to consumers. Grain and legume magnetic separators, acting as the “front-end gatekeeper” of the grain and legume processing line, utilize the principle of magnetic field adsorption to efficiently separate magnetic metal impurities from raw materials, ensuring smooth processing.
To understand the workings of a magnetic separator, you first need to understand its core components. These components work together to form the complete magnetic separation process:
The feed device, including a feed hopper, conveyor belt, or screw feeder, is responsible for evenly and stably conveying the processed grains/beans to the magnetic separation area, preventing accumulation or excessive flow that could lead to incomplete separation.
The magnetic separation core unit, the “heart” of the equipment, comes in two main configurations: a permanent magnet drum and a suspended magnetic separator (selectable depending on the processing scenario). It houses highly magnetic neodymium iron boron permanent magnets.
The separation and impurity removal device, including scrapers, guide plates, and a waste collection box, separates metallic impurities attracted by the magnetic field from the raw materials and centrally discharges them.
“Achieve Precise Metal Impurity Separation in Three Steps”
Step 1: Uniform Feeding and Stable Conveying
Grains/beans to be processed enter the equipment through a feed hopper and are transported at a constant speed to the top of a permanent magnetic drum via a conveyor belt (or screw feeder).
The feed mechanism controls the thickness of the material (typically 5-10 cm) by adjusting a baffle to ensure that every grain and bean reaches the magnetic separation area, preventing impurities from being trapped in the underlying material due to excessive thickness.
Step 2: Magnetic Field Capture to Capture Metal Impurities
A circular array of NdFeB permanent magnets is fixed inside the permanent magnet drum. The drum’s outer shell rotates with the drive system, driving the raw materials on its surface forward.
As the raw materials pass over the drum’s surface, they are exposed to a strong magnetic field. Magnetic metal impurities (such as nails and iron filings) are strongly attracted to the drum’s surface, while non-magnetic grain and bean particles remain unaffected and continue to be transported forward along the conveyor belt (or drum).
Key Advantage: The high magnetic properties of NdFeB permanent magnets enable “deep absorption.” Even iron filings embedded in the grain or beans or encapsulated in the raw materials can be precisely captured, achieving an absorption rate of up to 99.5%. Above.
Step 3: Impurity Separation and Centralized Disposal
When the drum shell, holding the metal impurities, rotates into the magnetic field blind zone (the area below the drum where the permanent magnets are not installed), the magnetic field disappears, and the metal impurities lose their attraction. Gravity forces them off the drum surface and into the waste collection box below.
Meanwhile, the purified grains and beans, free of impurities, are transported via guide plates to the next processing stage (such as screening, polishing, and grinding), completing the entire magnetic separation process.
In mung bean processing lines, magnetic separators are typically installed before polishing machines, creating an efficient process of “magnetic separation to remove impurities → polishing to improve quality”:
The magnetic separator first removes impurities such as nails and iron filings from the mung beans, preventing them from scratching the polishing rollers or embedding themselves in the bean surface during polishing, thereby affecting the polishing effect.
The pure mung beans, after magnetic separation, enter the polishing machine, where they come into more uniform contact with the polishing rollers, further improving impurity removal and surface gloss, ultimately producing high-quality finished mung beans.
Post time: Sep-04-2025
