A stone removing machine is a device used to remove stones and other impurities with high specific gravity from grains. The processes of different types of stone removing machines (such as gravity grading stone removing machines, suction-type specific gravity stone removing machines, etc.) vary slightly, but the core principle is to separate materials based on the differences in physical properties such as the specific gravity and suspension velocity between the materials and stones.
The Basic Structure of a Stone Removing Machine
Before understanding the process, let's first get acquainted with its main components, which helps in comprehending the role of each link:
Feeding Device: Consists of a feeding hopper and a flow regulating mechanism to ensure uniform and stable entry of materials.
Stone Removing Working Surface: Typically an inclined sieve plate with fish-scale holes or sieve holes, serving as the core area for separating stones.
Fan and Air Volume Adjustment System: Provides upward airflow to make materials suspended, facilitating separation from stones.
Stone Discharge Device: Collects and discharges the separated stones. Some equipment is equipped with a water washing function to clean the stones.
Discharge Outlet: Transports the separated clean materials.
Detailed Explanation of the Working Process of Gravity Grading Stone Removing Machine
1. Material Pretreatment and Feeding
Material Preparation
Grains to be processed (such as wheat, paddy, etc.) must first undergo preliminary cleaning to remove large-particle impurities (such as straw and broken shells) to avoid blocking the stone removing machine.
Uniform Feeding
Materials fall into the stone removing machine through the feeding hopper. The flow regulating mechanism (such as a gate or vibrating feeder) controls the feeding speed to ensure that the materials form a uniform material layer on the sieve plate (usually 2–5 cm thick). Uneven feeding will reduce the separation effect.
2. Interaction Between Airflow and Materials (Stratification Stage)
Airflow Action
The upward airflow generated by the fan passes through the fish-scale holes or sieve holes of the sieve plate and contacts the falling materials.
Specific Gravity Stratification
Due to the difference in specific gravity between grains and stones (the specific gravity of grains is generally 1.1–1.4, and that of stones is about 2.5–3.0), the buoyancy of the airflow makes the grains suspended or loose, while the stones sink relative to the sieve plate due to their high specific gravity, forming a stratification effect of "grains on the top and stones at the bottom".
Sieve Plate Vibration Assistance
The stone removing working surface usually vibrates at a certain frequency (such as 300–500 times/minute) and amplitude (2–4 mm) to further promote material stratification and push the stones toward the high end of the sieve plate.
3. Separation and Conveyance of Materials and Stones
Movement and Discharge of Grains
The grains suspended in the upper layer slide downward along the sieve plate under the action of their own gravity and the vibration of the sieve plate, and are discharged from the discharge outlet at the low end of the sieve plate as preliminarily de-stoned clean materials.
Collection and Discharge of Stones
Stones that sink to the bottom of the sieve plate move toward the high end of the sieve plate under the action of vibration and enter the stone collection area. Some equipment is equipped with a regulating device (such as a baffle) at the stone outlet to control the amount of grains entrained in the stones and reduce material loss.
4. Cleaning and Treatment of Stones (Optional Step)
Water Washing for Stone Removal (if available)
Some stone removing machines are equipped with a water washing tank. After the stones enter, they are washed by water flow to further remove attached grain dust or small-particle materials. The cleaned stones are discharged from the stone discharge port, and the sewage can be recycled after treatment.
Secondary Air Separation Treatment
High-end stone removing machines may add secondary air separation before stone discharge, using airflow to separate the small amount of grains mixed in the stones again, improving the stone removal efficiency.
5. Discharge and Subsequent Treatment
Collection of Clean Materials
Grains discharged from the discharge outlet are transported to the next process (such as flour milling, shelling, etc.) through a conveyor belt or pipeline.
Equipment Operation Monitoring
During operation, parameters such as air volume, sieve plate vibration frequency, and material layer thickness must be monitored in real time to ensure the separation effect. For example, excessive air volume may cause grains to be discharged with stones, while insufficient air volume will lead to incomplete stratification.
Key Process Parameters and Influencing Factors
Air volume control: Adjust the air velocity according to the type of material (e.g., the air velocity for wheat stone removal is approximately 3-4 m/s), which needs to be precisely regulated through the fan damper.
Sieve plate inclination: Typically 5°-12°. A larger inclination increases the sliding speed of materials, requiring coordination with the vibration frequency to avoid excessive thickness of the material layer.
Vibration frequency and amplitude: Excessively high frequency or large amplitude may cause materials to jump, affecting stratification; conversely, insufficient pushing effect will occur.
Material layer thickness: Excessive thickness makes it difficult for stones at the bottom to move, while too thin a layer reduces processing capacity. It needs to be adjusted according to the equipment model and material characteristics.
Maintenance and Process Optimization of Stone Removing Machine
Regular cleaning: Remove the materials or stones blocked in the sieve plate holes to avoid affecting the airflow distribution.
Inspection of component wear: Check components such as the sieve plate, vibration motor, and fan impeller. Replace them in a timely manner if severe wear is found.
Process optimization direction: Integrate an automatic control system to monitor the material layer thickness and impurity content in real time, automatically adjust the feed volume and air volume, and improve the stone removal efficiency and stability.
Process Differences of Other Types of Stone Removing Machines
Suction-type specific gravity stone removing machine: Negative pressure is generated through the upper suction port, combined with the vibration of the sieve plate. The separation principle is similar, but the airflow direction is different, making it suitable for scenarios with high requirements for dust control.
Combined stone removing machine: Integrated with functions such as screening and air separation, it can remove light impurities while removing stones. The process is more complex, but the efficiency is higher.
Summary
The core process of a destoner machine is to utilize differences in physical properties, achieving the separation of materials and stones through the effects of air flow, vibration, etc. Specific operations require adjusting parameters according to the equipment type and material characteristics to achieve the optimal stone removal effect.
Where can I purchase processing equipment?
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