Processing: Particle Reduction

Cracked corn, flour, grits, ground corn, soy flakes, crumbles—does this sound like a blog about grain operations? Many of you may associate me with grain operations, which constituted the bulk of my career. However, I began my journey in the industry with thirteen years in feed manufacturing, starting with Allied Mills (Wayne Feeds), followed by Ralston Purina and finally ADM. During my tenure, I worked in ten different mills, ranging from old-line plants to fully automated batching and pelleting facilities, liquid and pressed blocks, and pet food extrusion. I managed a facility focused on experimental pelleting, utilizing various die configurations and steam applications. I concluded my career as the Director of Manufacturing for ADM feed before transitioning to VP of Operations and Engineering for ADM’s global grain handling facilities. Additionally, I oversaw safety and food safety programs for ADM’s flour mills and founded the internal continuous improvement group aimed at enhancing performance in flour, corn, soy milling facilities, and bio-products.

Throughout my feed and processing experience, one critical process has always been particle reduction. This vital procedure enhances efficiency and product quality by mechanically breaking down larger particles into smaller, more uniform sizes and shapes, which is essential for optimizing feeding results, product appearance, performance, and process efficiency. Whether in the feed milling sector, flour production, or processing commodities like soybean meal, particle size reduction significantly influences the final products' performance and quality.

Different industries employ particle reduction for various reasons. In animal feed production, reducing grain particle sizes can improve digestibility and nutrient absorption, leading to better growth rates and efficiency. In flour milling, achieving the right particle size is essential for producing high-quality flour with consistent baking properties. Similarly, in soybean meal processing, proper particle reduction ensures improved oil extraction rates, better mixing, enhanced protein availability, and greater palatability for livestock.

Several types of equipment are used for particle reduction, with hammermills and roller mills being the most prominent. Other specialized equipment, such as crushers, pulverizers, ball mills, disc attrition mills, and pin mills, are utilized for specific applications. This post will focus on hammer and roller mills.

Hammer Mills - Hammer mills use rotating hammers to impact the material, breaking it down through a screen.

Pros:

- Versatility: Hammer mills can handle a wide range of materials, including grains, oilseeds, and by-products, making them suitable for various applications.

- Fine Particle Size: They are effective in producing fine particles, which can enhance the digestibility and utilization of feed ingredients.

- Simple Design: The straightforward design of hammer mills often makes them easier to operate and maintain compared to more complex milling equipment.

- Versatile for various materials, including those with higher moisture or fiber content, high capacity for large-volume grinding, simple design

Cons:

- Heat Generation: The high-speed operation of hammer mills can generate heat, potentially affecting the nutritional quality of sensitive materials like oilseeds.

- Dust Generation: Hammer mills can produce more dust during operation, which may require additional dust control measures to ensure a safe working environment.

- Variability in Particle Size: Achieving a consistent particle size can be challenging, as the final size is influenced by factors such as screen size and material flow rate.

Roller Mills -Roller mills use rotating cylindrical rollers to crush or grind materials by applying pressure and shearing forces based on design and gap clearance between the rolls.

Pros:

- Uniform Particle Size: Roller mills are known for producing consistent and uniform particle sizes, which is critical for applications like flour milling and specific feed formulations.

- Better Control: They provide greater control over the grinding process through adjustable roll spacing and speed, allowing for tailored particle sizes based on requirements.

- Reduced Heat Generation: The grinding action of roller mills typically generates less heat than hammer mills, preserving the integrity of sensitive materials.

Cons:

- Higher Initial Cost: Roller mills can be more expensive to purchase and install compared to hammer mills, which may be a consideration for smaller operations.

- Limited Versatility: They may not be as versatile as hammer mills, handling specific materials better than others.

When it comes to roller mills, different roll designs play a significant role in the milling process. Common roll designs include:

1. Smooth Rolls: Smooth rolls are used for producing fine products. They create a shearing action that helps achieve a uniform particle size, making them ideal for flour milling.

2. Grooved Rolls: Grooved rolls have indentations that create a more aggressive grinding action. They are effective for breaking down harder grains and are often used in feed milling , flour millings, and soy processing applications.

3. Combination Rolls: These rolls feature both smooth and grooved surfaces, allowing for versatility in milling operations. They can be adjusted to produce a range of particle sizes depending on the desired end product.

4. Corrugated Rolls: These rolls have a series of ridges and grooves that increase the grinding surface area, making them highly effective for coarse grinding applications.

5. Flaking Rolls: Flaking rolls are a specialized type of roller mill that are particularly beneficial in both the feed and soybean processing industries. These rolls are designed to flatten grains and seeds into flakes,

By selecting the appropriate roll design and employing the right combination of equipment, processors can optimize the particle reduction process to meet the desired customer need.

Maintenance

Maintenance is a critical aspect of ensuring the longevity and efficiency of particle reduction equipment. Regular inspections and maintenance routines help identify potential issues before they become significant problems, thereby reducing downtime and operational costs.

For roller mills, one key maintenance consideration is the life of the rolls. The rolls are subject to wear over time due to the constant grinding and crushing of materials. The type of material being processed, the moisture content, and the overall operating conditions can all affect roll life. Regularly monitoring the condition of the rolls and assessing their wear can help determine when they need to be replaced or reconditioned. This proactive approach can prevent unexpected equipment failures and maintain consistent product quality.

The setup of milling equipment, whether hammer mills or roller mills, is crucial for optimal performance. Proper alignment, calibration, and configuration of the machinery can significantly influence the efficiency and effectiveness of the milling process. It is essential to ensure that the equipment is set up according to the manufacturer’s specifications, allowing for maximum throughput and consistent particle size.

Training for operators is equally important. Well-trained personnel can optimize the milling process, troubleshoot issues promptly, and ensure that safety protocols are followed. operations. Training operators to recognize signs of wear, inefficiencies, and potential safety hazards is vital. Operators should understand how to adjust settings based on materials and desired particle size, as well as how to perform routine maintenance tasks. This knowledge empowers them to keep the equipment running smoothly and ensures that they can respond effectively to any issues that arise.

In summary, when it  comes to particle , both hammer mills and roller mills have their unique advantages and disadvantages.

Selection between the two should consider the specific processing requirements, the types of materials being processed, and the desired finished  product. Proper setup, training, and maintenance practices are essential to maximizing the performance and lifespan of milling equipment, leading to improved product quality and operational efficiency .

Thank you for taking the time to read this post! Whether you’re a farmer, a grain elevator operator, processor, or simply interested in agricultural technology; it’s good to review the basics from time to time and explore the wealth of innovation available to  discover. Your feedback fuels this blog, so don’t hesitate to share your thoughts or personal experiences. Together, we can cultivate a better understanding of modern grain handling and processing.

Best wishes, 

Grain Guy Fifty