Principles:
A heavy, flat stone or metal wheel rotates on a horizontal axis in the edge runner mill. The rotating wheel crushes and shears the material to be ground, which is fed between the wheel and a stationary base, achieving the grinding action through the generated crushing and shearing forces.
Construction:
1. Runner Stone: A heavy, flat stone or metal wheel that rotates on a horizontal shaft. The runner stone is often made of granite, basalt, or metal and is typically larger in diameter than the base stone.
2. Base Stone: A stationary flat surface against which the material is crushed. It provides support for the runner stone and helps create the grinding action.
3. Vertical Shaft: A drive mechanism imparts rotational motion to the vertical shaft, which is connected to the mounted runner stone.
4. Feed Mechanism: Feeding the material to be ground between the rotating runner stone and the stationary base stone usually occurs near the center of the mill.
5. Scrapers: Blades or scrapers attached to the arms of the runner stone ensure a continuous feed of material into the grinding zone.
Working:
1. Material Feeding: The material is fed between the rotating runner stone and the stationary base stone.
2. Crushing and Shearing: The rotating motion of the runner stone crushes and shears the material against the stationary base stone, resulting in size reduction.
3. Continuous Feed: Scrapers or blades attached to the arms of the runner stone ensure a continuous feed of material into the grinding zone.
4. Discharge: The reduced material exits the mill from the periphery of the grinding zone.
Uses:
1. Grinding and Crushing: The primary use of the edge runner mill is for grinding and crushing materials into fine powders.
2. Mixing and Blending: It can be used for mixing and blending purposes, especially in the preparation of wet pastes.
3. Size Reduction of Wet Material: Particularly effective for size reduction of wet materials due to the crushing and shearing action.
Merits:
1. Simple Design: The edge runner mill has a simple and robust design, making it easy to operate and maintain.
2. Versatility: Suitable for a wide range of materials, including those that are wet, sticky, or contain moisture.
3. High Crushing Efficiency: The crushing and shearing action of the rotating wheel allows for effective size reduction.
4. Cost-Effective: Compared to some other grinding mills, the edge runner mill is often considered cost-effective.
Demerits:
1. Low Energy Efficiency: Edge runner mills may have lower energy efficiency compared to some modern grinding mills.
2. Limited Control over Particle Size: Achieving precise control over particle size distribution can be challenging with edge runner mills.
3. Wear and Tear: The contact between the runner stone and the base stone can lead to wear and tear, requiring maintenance and replacement of parts.
4. Limited Scale: May not be suitable for large-scale industrial applications due to limitations in throughput and efficiency.
The edge runner mill is a traditional grinding mill that has found applications in various industries. Understanding its principles, construction, working, uses, as well as merits and demerits is essential for assessing its suitability in different processes.
