Choosing the Right Equipment: A Guide to Prater’s Product Line

When it comes to managing bulk materials, there are numerous types of size-reduction equipment available. When purchasing such machinery, it's essential to consider factors like initial investment, energy efficiency, and ongoing operational costs. Additionally, the noise levels and dust production should not be overlooked. Custom-built equipment generally outperforms off-the-shelf alternatives, making it crucial to partner with a manufacturer who can offer tailored solutions and optimize their performance within your specific system. Many manufacturers also conduct material tests for clients to ensure the machinery meets their exact requirements. Comprehensive testing helps in selecting the right equipment and minimizing the need for on-site adjustments. Prater Industries is renowned for its high-quality size reduction equipment and customer-centric approach in the bulk material processing industry.

Different Types of Size Reduction Equipment from Prater

Prater’s test lab enables customers to identify which type—or types—of particle selection equipment best suit their needs. Our engineers are always ready to assist with particle size reduction, separation, and other material handling solutions. Furthermore, we provide a handy tool for prospective customers visiting our website to determine the machinery they need. Prater’s equipment selector tool helps our customers choose the best types of size reduction equipment for their applications. Not only does it suggest which machines can process material to a specific particle size, but it also includes animations demonstrating how material moves through each piece of equipment—understanding how our products process material helps companies customize their systems to produce the particle size and separation solutions they require.

Let’s now explore Prater’s product lineup to determine what types of size reduction equipment will meet your facility’s needs.

Lump Breakers

Lump breakers are also commonly referred to as flake breakers or lump crushers. These robust pieces of size reduction equipment are part of most material processing systems. They help break down agglomerated product, conditioning materials that have become compressed due to blending processes, during transfer, or while in storage.

Using relatively gentle impact and shear forces simultaneously, these machines streamline production by improving flowability and enhancing product quality. The single-shaft models distinguish Prater’s Lump Breakers from flake breakers, which have a lower profile and two shafts. Both types of equipment are also used for scrapping and recycling operations and to reduce agglomerated material.

Features of Prater’s standard Lump Breakers include:

• Ability to reduce product into particles ranging from 1/₁₆ inch to 6 inches (about 0.16 cm to 15.24 cm).
• Both fixed and rotating, readily replaceable blades.
• Drilled for air purge seals to prevent material buildup, protect seals and bearings, maintain product purity, improve efficiency, control dust, and enhance safety.
• Durable single-shaft rotor with V-belt drive includes an OSHA guard to protect machine operators.
• Dual-shaft Flake Breakers include a direct drive for compact, streamlined installation.
• Options available include hygienic design.

Our engineers have also developed a model that is easier and safer to clean and maintain. Similar to our Quick-Take-Apart rotary airlock valves, it allows tool-free access to the drive. The drive unit smoothly slides out on the mounted rail system for convenient access. This upgraded model offers manufacturers increased uptime and reduced dust in production compared to our standard model.

Features of Prater’s Quick-Clean Lump Breaker include:

• Access for cleaning and maintenance via a toolless endplate design.
• Design has fewer moving parts without any pinch points on the machine’s direct drive.
• Drilled for air purge seals so as to prevent material buildup, protect seals and bearings, maintain product purity, improve efficiency, control dust and enhance safety.
• Durable single-shaft rotor.
• Ergonomic rail design allows easier handling of the rotor, preventing any awkward positioning that can increase the risk of injury during maintenance.
• Lower profile makes installation and servicing easier.
• Rotating and fixed blades that are easily replaced.

Both types of size reduction equipment can be used to process materials such as ash, detergents, fertilizer, paper waste, rubber, and sulfur.

Hammer Mills

Previously known as the Prater Pulverizing Company, the company initially produced the Prater Pulverizer, laying the foundation for modern hammer mills. Prater engineers consistently incorporate cutting-edge technology into their hammer mills to enhance material processing capabilities. The Prater G-series represents a full-screen hammer mill crafted for high throughputs, ensuring energy efficiency and uniform particle size. With a focus on maximizing productivity, their screen technology effectively captures material from the grinding chamber, reducing processing energy and operational expenses.

Features of Prater’s full-screen hammer mill include:

• Able to accommodate various hammer arrangements due to greater width of rotors.
• Construction available in either carbon steel, 304, or 316 stainless steels.
• Designed for easy access to replace worn parts.
• Direct drive models are available that turn in either 50 or 60 cycles per second.
• Electronically balanced reversible rotors that enable feed from the top.
• Fully feeding from the top and along the width of the machine allows complete use of the screen area.

Prater’s Mega Hammer Mill processes material to a consistency between our standard Hammer Mills and Fine Grinders. It operates smoothly and quietly, avoiding heat buildup with consistent grinding. The Mega hammer mill is designed for minimal downtime, requiring less airflow than Prater’s standard hammer mills. It is built to run continuously, needing less power and maintenance.

Features of Prater’s Mega Mill hammer mill include:

• Distinctive rotor design includes a cantilever and hinged doors for easy access to maintain and clean the interior.
• Dust-tight design makes it ideal to use with pneumatic conveying systems.
• Precision-balanced rotor and bearing assembly to ensure a longer lifespan and smooth operation.
• Durable construction for extended lifespan.
• Horsepower-to-screen ratio maximized to ensure uniform grinding and optimal throughput without significant heat buildup.
• Screens and rotors designed for easy removal and replacement.
• Well-positioned interrupter plates boost grinding while allowing easy screen removal and replacement.
• Wide array of materials can be effectively processed due to a variety of hammer shapes and styles for optimizing processes.

Both types of hammer mills can be used to process materials such as barley, clay, gelatin, oats, potatoes, and vermiculite.

Fine Grinders

Prater's Fine Grinders use high-speed impacts to break down raw materials introduced into the mill through measured feeding. These machines, often called fine grinding mills, move material across screens and jaws, creating shear and impact forces. Stationary features slow down particles, allowing them to bounce back to the rotor blade's path. Once properly sized, the material is pulled through the screen apertures. 

Prater's M-series Fine Grinders pulverize materials down to 400 mesh (37 microns) with a more uniform size distribution. The design enables easy rotor access, ensuring close tolerances between the grinding components for finer particles. Despite having a larger screen for its power, the fine grinder can handle substantial throughputs.

Features of Prater’s M-series Fine Grinders include:

• Bearing assembly located on the exterior of the machine for accessibility.
• Design with dual O-ring door seal that includes a floating door hinge helps achieve positive seal.
• Grinding blades are replaceable.
• Option for hygienic construction.
• Reversible rotor assembly that’s balanced dynamically.
• Sizing between 60 to 400 mesh (250 to 37 microns) of final product particle size.
• Tight tolerances between stationary grinding elements and the rotor.

The 10-bar Fine Grinder is built to withstand explosions, with a pressure limit of 145 psi (equivalent to 10 bar). It processes heat-sensitive materials into precise particle sizes and offers bearing monitoring for early failure detection.

Features of Prater’s 10-bar Fine Grinders include:

• Durably constructed with stainless steel or welded carbon steel.
• Easily maintained via large access door and well-placed internal components.
• Due to its simple yet elegant design, Free-flowing and drier materials can be ground in a single stage.
• Internal electrostatic discharge is mitigated by a standard form of shaft grounding brush.
• Offers greater versatility due to multiple screen and jaw combinations.
• Options include monitoring software that augments predictive maintenance planning, as well as hygienic design.
• Ratio between the horsepower and large screen allows larger throughputs.
• Replacement of grinding blades, jaws, and screens requires little effort.
• Tight tolerances between the grinding jaw, screen, and rotor blade allow reduction of homogenous particle size.
• To maximize bearing lifecycle, the machine is designed with an externally affixed spindle featuring high-quality labyrinth seals.

While Prater’s 10-bar Fine Grinder specializes in processing environments where dust explosions are a factor, such as sugar grinding (from 4X to 12X), our M-series Fine Grinder can process materials like charcoal, coffee, flour, limestone, resins, and wheat. 

Air Classifying Mills

Categorized as a classifying impact mill, Prater’s Air Classifying Mills use a dual-stage milling and grinding process that integrates an air classifier into the milling machine. The air classifier recirculates material within the mill while the machine is running, continuously sending oversized particles back to the grinding zone until they reach the desired size. Prater's air classifying mill provides a rational solution for products that require a narrower range of particle distribution or if they’re simply more challenging to grind. Like other types of size reduction equipment made by Prater, it allows easy cleaning and inspection of the machine’s internal parts, including the classifier and main rotor.

Features of Prater’s air classifying mills include:

• Classifies product via moving air between different stages of reduction.
• Easy to inspect and clean through conveniently positioned access door.
• Grinds material’s particles to between 50 mesh (297 microns) and sub-micron levels.
• Offers two stages of grinding within a closed circuit.

Prater’s air classifying mill can process materials like activated carbon, corn meal, iron oxide, lactose, salt, and zinc oxide.

Rotary Airlock Valves

In many material handling systems, rotary airlock valves are essential. These mechanisms work with different types of size reduction equipment, such as airlocks, feeders, or even both airlocks and feeders. Rotary Airlock Valves made by Prater help material processing systems perform better, mitigating dust explosions. Our valves provide precise unloading and loading of materials for metering dry materials, though they can also function as efficient rotary airlocks that minimize pressure loss. Prater manufactures various rotary airlock valves, each uniquely designed for specific applications.

Prater’s rotary airlock valves include:

• Abrasion-resistant rotary airlock valves: Explicitly designed to handle abrasive materials, this model features hardened rotor tips and premium seals, along with superior wear coatings made from ceramics, chrome, or tungsten that come standard.
• Blow-through rotary airlock valves: For use with pneumatic conveying systems, this model works well for free-flowing materials and is designed to help clear the pockets of the rotor vane; this particular model is also useful for installations where there’s very little headroom and for retrofitting existing valve systems.
• Dust collector rotary airlock valves: Prater’s Dust Collector Series is cost-effective and general-use valves that work well when placed under cyclones, dust collectors, or hoppers. It has similar features to our heavier-duty valves.
• Heavy-duty rotary airlock valves: Designed to be a workhorse in material handling applications, this model offers multiple options for rotor construction, seals, and other accessories. Also known as Prater’s PAV (positive airlock valve) series, it can work in both pneumatic and gravity-operated systems.
• Quick-take-apart rotary airlock valves: Designed with a demountable rotor and a direct drive, Prater’s QTA valves can be maintained without tools. Pre-gapped rotors eliminate the need to adjust after installation.
• Quick-take-apart rotary airlock valves on rails: This is essentially Prater’s QTA valve but with the rotor demounted using a rail assist. Compared to a valve without rail assist, Prater's design reduces the hazards associated with removing the rotor.   

Rotary airlock valves are important in processing applications where dry and free-flowing materials are handled, whether as powders, pellets, granules, or crystals. Prater’s rotary airlock valves are commonly used for cement, fly ash, lime, ores, pharmaceuticals, and sugar.

Other Prater Equipment

We manufacture various other kinds of machinery in addition to the various types of size reduction equipment Prater makes.

Other equipment made by Prater includes:

• Rotormills: Prater's rotormills are known as “long-gap mills” due to the lengthy, ring-shaped gap between where material enters and is then discharged. They work across a wide range of applications, including in the agriculture, chemical, energy, food processing, geotechnical, metallurgy, pharmaceutical, and waste management industries.
• Rotary sifters: Known as the Rota-Sieve®, Prater’s branded rotary sifters use lightweight components and a simple design to sieve materials for foreign objects or contaminants like insects, plastics, rocks, or strings.
• Mini-split air classifier: Developed for research or small-scale production, this pneumatic classification device is compact and portable that promotes a dust-free and low-noise environment.
• MAC air classifier: Able to process dry materials uniformly and to a remarkably fineness, these air classifiers can be used either within an existing milling system or as a standalone system that incorporates a fan, feeder, and container for finished material.  
• Rotordryer®: Combining the rotormill with a heat source creates a flash drying system for use with slurries and drying materials containing a great deal of moisture; this system is ideal for processes that require continuous fine milling at high throughput rates.

To learn more about our product lines and services to support our customers, contact the material handling experts at Prater today.