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Full Circle Screen Hammer Mills: Low Horsepower, High Throughput

Posted by Cassie Brown

Jul 20, 2012 12:59:00 PM

high production full circle screen hammer millSize reduction equipment comes in a wide variety of shapes and sizes: vertical or horizontal hammer mills, jaw crushers, roller mills and ram-fed grinders, just to name a few. For the most part, the size and shape of the mill/grinder/crusher plays a key role in the functionality of the machine, and for the applications it is best suited for. Nowhere is this truer than with the Full Circle Screen Hammer Mill.


A Peek Inside...

The full circle screen hammer mill gets its name from the 300 degree screen coverage of the rotor, while all other styles of hammer mills typically have closer to 180 degree coverage of the rotor. 

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 Full circle screen hammer mills                                 


Ideal Applications

To achieve the circular, nearly full coverage of the rotor requires that the screen be somewhat pliable, and therefore relatively thin. In addition, the full circle screen mills use thin, notched hammers that reduce material with a tearing/grinding action, as opposed to the pulverizing effect of the large, heavy hammers often used in the industrial hammer mills. As a result, the full circle mills are best suited for light, easy to grind materials that do not require initial grinding against a breaker plate. 

Some examples include:

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 Size Reduction 101

When material enters the grinding chamber, it is repeatedly struck by hammers that flail out as the shaft spins.  A combination of these hammer blows, particle on particle impact, and impact with the walls of the grinding chamber all work together to break the material down. The material remains in the grinding chamber until it is reduced to a size that will pass through the screen. 

The larger the screen area, the greater the opportunity for the material to evacuate the mill. As a result...

 full circle mills.throughput

 Additional Considerations

Once you have decided that the full circle screen hammer mill is best for your material, determining the following criteria will ensure so that the mill is configured to meet your production goals:

  • Material being processed -  Material characteristics such as: friability, flowability, moisture content, and infeed size
  • Desired finished particle size  - Sawdust, granules, coarse or fine powder?
  • Desired production rate - 10 lbs/hr, 10 tph, etc.

With this information, the following can then be determined:

  • Hammer mill size - Rotor diameter and internal mill width.
  • Hammer size and style - Number of hammers, size, style and metallurgy.
  • Screens  - Style and thickness of screen, and size of openings.
  • Choice of proper RPM
It's Optional
Finally, once the the mill is configured, the last determination is whether or not any optional peripheral equipment is needed. For this, the following questions must be answered:
  • How will the material be fed into the mill? By hand, auger, or belt conveyor?
  • How will the material be taken from the mill? Gravity, air assist, or full air evacuation?
  • Is dust a concern?

Answers to these questions will help to determine the best types of optional equipment such as belt conveyors, augers, rotary feeders, and dust collection, as well as the most efficient design of the infeed and discharge chutes.  


intro to size reduction ebook





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Topics: full circle screen hammer mills, particle on particle contact, biofuels, briquetting, bio-fuel applications, circular hammer mill, corn, animal feed, corn meal, corn flour, hammer mill design styles

How to Convert Waste Wood to Biofuel Feedstock

Posted by Cassie Brown

Feb 14, 2012 10:06:00 AM

Got Waste Wood? Convert to Biofuels!
Size reduction solutions to two of the biggest challenges when converting waste wood to biofuels

Throughout our 80+ year history, wood processing has been one of our cornerstone industries. Among our largest customers are forest products companies, lumber yards, makers and recyclers of pallets, furniture manufacturers, truss plants and more. Each with unique products, but all with one common issue: wood waste. The level of waste varies depending on the industry.  An interesting example is forest products companies. When processing logs for lumber, up to 40% of the tree is deemed scrap in terms of its lumber value.

Traditionally, these by-products were considered waste, and at best, used as onsite boiler fuel or sold at a minimal profit to local buyers for such uses as landscape mulch and  animal bedding.  Enter biofuels.  Amid growing environmental concerns and the desire to reduce dependence on fossil fuel, the emphasis on biofuel creation continues to increase.  As a result, wood has emerged as an ideal feed stock. Now the wood waste once seen as a disposal problem is now a valuable product.

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But here is the hitch - each of the potential biofuel end products have specific material characteristics that are critical to their effieciency. As a result, there are a number of challenges inherent in using a non-uniform scrap material as biofuel feed stock. In two specific cases, hammer mills are instrumental in taking wood waste from the sawmill floor to the biofuel market.

To illustrate this point, let’s use the example of converting wood waste to pellets and briquettes.

Challenge No 1:                Particle size and uniformity

These are critical factors in the preparation of wood to biofuel feedstock. On average, most biofuels require a consistent feedstock particle size of -1/8”.  Typical waste wood as is much larger and non-uniform.

Hammer Mill Solution:

The first and most obvious consideration is size reduction. Can hogged wood scrap, bark, pallets, furniture scrap, etc be ground to a size that is appropriate for biofuel production? The answer is of course, yes. The solution lies in selecting the correct wood grinder for your production goals.

To determine this, the following must be considered:

    • Size and type of in-feed material
    • Desired finished particle size
    • Hourly production goals

Answering these questions will determine not only what wood grinder is most suitable for your application, but also whether your goals require a one or two stage grinding process.

For example, if your waste material is hogged wood scrap and your goal is a -1/8” for pelletizing, a finish grinding industrial hammer mill would be most appropriate.  From there, your production goals determine the size and style of the recommended mill.

Conversely, if your waste material is pallets and your goal -1/8” for pelletizing, you will require a two step process.  A slow speed ram fed grinder is ideal for the initial grinding of the whole pallets. However, this type of mill is not suitable for the fine grinding required for the optimal finished particle size for pelletizing. A secondary grind in a finish grinding industrial hammer mill will be necessary.  Typically, the material will be pneumatically drawn from the ram fed grinder, across magnets to remove all nails, and then though the finish grinder. The upside of this is that this pneumatic component can substantially increase the throughput rate and convey the finished product to storage.

Screen selection for the hammer mill is the second component in determining finished particle size. Referring again to our original three considerations, the desired end particle size will dictate the size of the openings on the perforated screen covering the discharge of the hammer mill.  For example:

Finished particle size of 1/8” will require a screen size of  1/4" or smaller.

The material will remain in the grinding chamber of the hammer mill until it is reduced to a size that will pass through the screen.

Challenge No 2:                Material moisture content

The majority of biofuel applications require a moisture content of ≤10%. However, it is not uncommon for waste wood, such as bark or green wood chips, to have ≥50% moisture content. Not only is the moisture content too high for fuel efficiency, it is also too high for a wood grinder to reduce the wood to a uniform particle size suitable for pelletizing.

Hammer Mill Solution

Under these circumstances, the solution is often a three phase process where hammer mills play a pivotal role. The following is an example of how one of our customers addressed this challenge. Their goal was to convert wood waste with an average 40 to 50% moisture content to suitable feed stock for pelletizing and briquetting.

An industrial wood grinder was used to pre-grind the green wood down to a uniform ½” particle size recommended for optimal drying in the rotary drier. The drier would reduce the moisture content down to the required ≤10%.   Finally, the material is fed into a second industrial wood grinder where it is ground to its finished particle size, ideal for the customer’s pellet and briquette production.


download wood grinders for biofuels  ecatalog


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Topics: finished particle size, green wood chips, moisture content, finish grinding hammer mill, biofuels, briquetting, grinders, bio-fuel applications, pelletizing, waste wood, bark, feedstock, rotary drier, processing wood

Welcome to Shop Talk

Posted by Cassie Brown

Feb 14, 2012 8:26:00 AM

Crush, grind, pulverize, shred... Size reduction is fascinating!

Welcome to Shop Talk, the official blog of Schutte-Buffalo Hammermill, LLC. We are a Buffalo, NY based manufacturer of custom engineered size reduction equipment, and we aim to become your trusted resource on its design, manufacture and usage. But first, a little background...


Yeah. It is a mouthful. Frequently misspelled and often mispronounced, but our verbose trade name has an interesting origin.

Back in the late 1920s two size reduction equipment manufacturing companies emerged in Buffalo, NY; each with their own distinct focus.

Schutte (pronounced shoot-ee) Pulverizer Company focused on processing organic materials, building an extensive line of gravity and pneumatic discharge hammer mills, earning them a leadership role in the fields of wood waste reduction and feed and grain processing.  Across town, Buffalo Hammermill Corporation was applying similar principles to more industrial applications such as mining, metals recycling and dry chemical processing.

Fast forward to 2001 and the two companies have merged. The result was Schutte-Buffalo Hammermill, but bigger changes were still ahead. In 2004, company President Tom Warne and General Manager Jim Guarino joined forces to purchase the company from retiring owner, Harry D. Schutte.

Small but Mighty

Post merger and now post acquisition, the new incarnation of Schutte-Buffalo Hammermill is still a company small in size, but one with an ever growing impact.  Even today the staff numbers just under 30, and 90% of the equipment fabrication takes place in "The Shop" adjacent to our corporate headquarters here in Buffalo.  However, we have seen tremendous growth in recent years.  Presently, our installations number more than 16,000 worldwide, serving a wider variety of industries and applications than any other size reduction machinery manufacturer.

Continued Innovation

A key component in this growth and the overriding theme of the Warne / Guarino era has been innovation. Building on the success of Schutte-Pulverizer Co. and Buffalo Hammermill Corp, the time proven principles of size reduction technology and manufacturing have been applied to new and burgeoning applications.

Industrial hammer mill technology originally used to process coal and bulk chemicals has been adapted to de-manufacturing electronics for recycling, and for dismantling spent military munitions.  Similarly, machinery developed for processing wood for mulch production or animal bedding has been applied to processing wood for a myriad of bio-fuel applications.

Just to name a few...

Stay Tuned

Size reduction is amazing! And the application possibilities are virtually endless. In future posts we will share our knowledge about the principles of size reduction and our experiences in greater detail. Some of the general topics will include:

    • The basic principles of size reduction

    • An in-depth look at different hammer mill components and their functions

    • Applications: from the commonplace to the very, um.. unique materials processed in hammer mills.

    • A comparison of the different types of size reduction equipment and their uses.

And much more!

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Topics: hammer mill, bio-fuel applications, processing wood, size reduction equipment, Schutte Pulverizer Company, mulch production, de-manufacturing electronics, Buffalo Hammermill Corporation, Schutte-Buffalo Hammermill