Introduction
When processing rice, have you noticed that there are many impurities in the rice grains? You must clean the rice thoroughly before processing, or the impurities can damage your rice processing machines. Next, I will explain a machine that can remove stones from the rice—called a destoner machine. I hope this helps you process your rice more smoothly!
What is a Destoner Machine?
The gravity stoner is a machine used in the cleaning process before rice processing. It separates stones that are similar in size and shape to the rice grains, based on how quickly rice and stones float in the air. The machine also has a suction system that removes lighter impurities from the rice.
How does the Destoner Machine Work?
Components of the Destoner Machine
Feed Inlet: Also called the material feeding hopper, it is an angled part that extends from the front of the machine. This is where you put the material into the machine.
Storage Hopper: This temporarily stores the material to ensure a continuous flow of feeding and prevent air leaks.
Air Inlet: Located at the top of the gravity destoner, it works with the fan to create airflow inside the machine.
Air Suction Hood: Positioned below the air duct, it uses the airflow from the fan to separate the rice and remove light impurities, while also helping reduce machine noise.
Screening Body: Made of fish-scale-shaped screens and a stone removal device. It separates the rice from stones through vibration and airflow.
Observation Window: Located at the front, below the air suction hood, it allows you to observe the material on the screening body and make adjustments as needed.
Eccentric Drive Mechanism: Installed along the centerline symmetrically to the left and right of the screening body, it drives the screen to move in a back-and-forth vibrating motion.
Machine Frame: A simple structure that supports the weight of the machine and ensures it operates normally.
The Working Principle of the Destoner Machine
Before explaining how the gravity stoner works, it’s important to understand what “specific gravity” means. Specific gravity can be understood as the weight of a substance per unit volume. Rice has a low specific gravity, usually below 2.5, while stones have a higher specific gravity, usually above 4. This means that, for the same volume, stones are heavier than rice. The gravity stoner takes advantage of this difference in specific gravity to separate the stones from the rice.
A destoner is a machine that separates stones from grains by taking advantage of the difference in specific gravity between the two. It works through a combination of vibration and airflow.
When grains are fed onto the destoning table, they are brought into a suspended or semi-suspended state by the air stream. By adjusting the air pressure and vibration frequency, stones and grains are effectively separated. Because the lighter grains remain on the upper layer while the heavier stones settle at the bottom, the corrugated deck and its vibration cause the stones to move gradually forward by inertia instead of sliding downward, eventually discharging them from the stone outlet. This ensures efficient stone removal.
Advantages of the Destoner Machine
Efficient Heavy Impurity Removal
The fish-scale screen in the gravity stoner is designed to help stones stick to the screen and move upward with inertia. Combined with the screen’s vibration and the airflow, this design effectively creates a gap between the rice and stones, making it easier and faster to remove stones and light impurities from the raw material.
Improved Paddy Quality
At the beginning, the rice is mixed with stones, light impurities, and dust, which lowers its quality and can damage the rice processing equipment. By using the gravity stoner, you can remove most of the impurities from the rice, increasing its purity and improving the overall quality of the rice.
Environment Protection
The suction-type gravity stoner does not have a built-in fan. Instead, it uses an external fan for the airflow system. The whole machine is sealed, which helps prevent dust and impurities from escaping. This design meets environmental standards and allows you to work in a cleaner, more comfortable environment.
Factors Affecting Destoner Machine Performance
Flow Control
When the gravity stoner is operating, you need to feed the material continuously and evenly to avoid air leaks. If there is an air leak, the airflow system won’t work properly. Also, if too much material is fed in at once, the screen won’t be able to process it all, and stones may end up going into the clean rice outlet with the rice, reducing the efficiency of stone removal.
Independent Air Network
When the gravity stoner is working, it uses the air pressure from the fan to make the raw material float or partially float. This helps separate the stones from the rice. The airflow speed and pressure inside the machine directly affect the stone removal process. That’s why the gravity stoner must be equipped with an independent air network to ensure there is enough airflow.
Adjusting Airflow
It’s important to know that more airflow is not always better. When using the gravity stoner, you need to adjust the airflow to the right level so the raw material can float or partially float. If the airflow is too strong, it will disturb the floating layer of rice. If the airflow is too weak, the rice won’t float properly, and the material won’t separate into layers.
Adjusting the Screen Angle
Before using the gravity stoner, you need to adjust the screen angle, usually no more than 10°. If the angle is too small, both stones and rice can easily slide toward the stone outlet, causing too much rice to be lost. If the angle is too steep, the stones will have a harder time moving up the screen and will stay on the screen longer. This could cause the stones to fall into the clean rice outlet with the rice, lowering the quality of the rice.
How to Maintain the Destoner Machine
The most important part of the gravity stoner is its screening body. Next, I will explain how to maintain the screening body in three ways to ensure the best stone removal performance.
Keep the Screen Flat
The flatness of the screen is very important. Remember what I mentioned earlier? The fish-scale screens curve downward on one side. If the screen surface is uneven, the stones won’t be able to move up properly and will easily slide with the rice into the clean rice outlet. This will mix too many stones with the rice and increase your workload.
Regularly Clean the Screen
Some stones or rice, similar in size to the fish-scale screens, can block the holes. If the holes get blocked, the machine won’t be able to remove stones properly. To avoid this, you should clean the screen regularly to prevent too much blockage, ensuring the machine works smoothly. It’s a good idea to clean the screen for any blockages at least once a week.
Regularly Replace the Screen
During operation, stones climb up the screen, which causes some wear and tear. If the screen holes get worn down, the stones won’t be able to move up and be properly removed, which can affect the quality of the clean rice. It’s best to replace the screen once a month to keep the machine working efficiently.
Conclusion
As you can see, the gravity stoner is essential in rice processing. If you’re thinking about investing in a rice processing plant, make sure to choose a gravity stoner. Feel free to consult with us at ANON—we are experts in grain processing machinery!
FAQ
How much is the rice destoning machine sold?
We provide all kinds of rice destoner machines for sale at the best price. Please tell us your needed capacity, voltage & frequency to get the latest rice destoning machine price.
