Digital Re-print - March | April 2010
Feature title: Roller Mill Grinders
- Advantages, limitations and how roller mill grinders are changing for the better
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Roller mills Feature Feature Roller mills
Side bar: Obtaining a narrow particle size distribution
should add value to your process.
less energy than an attrition mill of the same However, materi-
r Mill Grinders
capacity. If you are wondering what savings als like wood, rubber,
Rolle
that means in dollars, an additional 10hp and soft plastics are
costs our factory US$6500/year (based on not good candidates
24/7/365 at US$0.10/kWhr). for roller grinding.
changing for the better
and how roller mill grinders are
Limited feedstock
Product Limitations
Advantages, limitations
size: The maximum
Due the low-impact grinding nature of size of the feedstock
ses, technologies and
y searching for new proces
ate, companies are constantl Scott Will, we will cover
roller mills, it is typically best suited for (unground material fed
In this current economic clim uce costs. In this article by
their organisations and red sing costs. We also
materials that break apart under pressure, to the roller grinder)
equipment to add value to and reduce long-term proces
value to many applications and efficiencies.
otherwise know at ‘friable’ materials. This varies based on the
how roller mill grinders add rove roller mill capabilities
rovements that further imp can range from polyester plastics used in material properties; roll
discuss recent technology imp solid surface countertops to coffee. Roller speeds and corruga-
mills are also superior grinding systems for tions, and other factors. “Roller-Style Grinders are typically
by Scott Will various abrasive materials such as limestone Generally, the feedstock must
more expensive than hammer
and elemental silicon. be 25.4mm (1 inch) or smaller.
In any case, we have listed the two most mills but give better particle size
more of these days.
Change for the better! Now that is something we all need a little common product requirements for success- Changing for the better distributions. If the only sizing
ful roller mill operation. Roller mill technology continues concern is to reduce the material
Only suitable for friable materials: The to evolve. below a certain size with no
product to be ground must fracture under One of the greatest advances in limits to the permissible amount
stress rather than flatten or deform. This technology involves roll materials.
of dust or size consistency, then
does not mean that the product must be Today, various material advances
brittle; a roller-style grinder can be used allow roller mills to be utilized in a roller mill grinder may not be
for products as hard as elemental silicon or increasingly abrasive applications. appropriate for your needs”
F
or those of you unfamil- rial in size to a narrow particle size limestone. No longer are we limited to steel
iar with roller mills, the Figure 1 distribution and with few unwanted
basic principal of operation fines (see Figure 2).
is simple: Two parallel rolls
rotate towards one another Roller mill advantages
at high speeds, say 400 – Now that we understand the basic
3000rpm. Material is gravity principles of operation, there are four
fed between the parallel rolls main advantages that direct people to We pride ourselves in implementing > Turnkey installations
and as it enters the ‘nip’ of use a roller mill rather than a hammer- the latest technological
the rollers, it experiences both mill, ball mill, cone mills or some other improvements > Cleaning equipment
crushing and shearing forces attrition grinding method. > Milling equipment
We strive for the highest quality
that grind the particle into Narrow particle size distributions.
& con dence in our products & > Transfer equipment
smaller pieces. Roll surfaces can Fracturing of the material is accom- services
be either corrugated or smooth plished only by the induced stress/shear > Extraction Control
on the surface, depending action of the roll surface on the prod- Our goal is complete customer > Packaging
on the need, and typically a uct. There is no attrition, high speed satisfaction in the production of
our our milling machines > Complementary machines
speed differential between the impact, or internal screening.
rolls, ranging from 1:1 to 3:1, For many materials, this results in
is necessary (see figure 1). significant narrowing of the particle size
distribution.
Most roller mills are compromised Minimal dust (fines) creation:
of multiple grinding sections vertically Without high speed impact, dust gen-
stacked on top of one another and eration is reduced.
material falls by gravity from one pair Low temperature rise: With no
of rollers to the next. high speed impact and since there Konya Organize Sanayi Bölgesi 7 Sokak
The number of sections is deter- is no recirculation of product inside
No: 3 Konya/TÜRKİYE
mined by the material properties and the grinder, heat generation is mini-
the amount of reduction required to mal. Also, grinding rolls can be cooled T: +90 332 239 1016 (pbx)
achieve the desired grind size. internally for especially heat sensitive F: +90 332 239 1348
The roll corrugations, speed products. E: unormak@unormak.com.tr
ratio between the rolls, and the gap Low energy consumption: There is
between the grinding rolls are all no high speed particle impact and zero
precisely engineered for each product.
The objective is to reduce the mate-
friction between particles; thus, a roller
mill grinder typically uses 30-50 percent
www.unormak.com.tr Realizing your future by your voice
Unormak.indd 1 24/11/2009 15:56
18 | march - april 2010 Grain &feed millinG technoloGy Grain &feed millinG technoloGy PREVIOUS PAGE NEXT PAGE march - april 2010 | 19
Roller mills Feature
s crudest
“Some may still think of roller mills in it
y pulverizing
form, w ith “crushers” haphazardl
But today’s
friable materials down to a reduced size.
to produce
precisio n roller mills are designed
pletely
“controlled explos ions” that achieve a com
d particle size”
contro lled and highly-engineere
Modern manufacturing methods and grinding, especially with polyester, acrylics
or even hardened steel rollers. Modern roller CNC machines provide precision equipment and other hard plastics. This is no longer
mills use exotic roll materials, various coatings tolerances that were simply not possible necessary with the advent of water-cooling
and in extreme cases ceramics that offer hard- years ago. on roller mill grinders.
ness values above the Rockwell C hardness Today, roll gaps can be held to 10 Additionally, various foods such as coffee
microns and pepper boil off volatile oils and aromas
(+/-0.0005 above 35 degrees C (95 degrees F). Water-
Figure 2 inch) while cooling eliminates product temperature rise
rotating at as materials pass through the grinder, thus
3000rpm. eliminating the need for expensive liquid
This allows nitrogen and simultaneously improving prod-
roller mills uct quality.
to grind
materi- Today’s precision rollers
als down Roller mill technology has evolved and
to 50 become much more refined over the past
microns, 50 years.
continu- Some may still think of roller mills in
ously and its crudest form, with ‘crushers’ haphaz-
accurately, ardly pulverizing friable materials down to
day after a reduced size. But today’s precision roller
day and mills are designed to produce ‘controlled
year after explosions’ that achieve a completely con-
year. trolled and highly-engineered particle size.
Water- Friable materials can now be reduced in size
cooling also with less dust, greater uniformity and higher
scale. These coatings and ceramics can virtually plays a part in expanding applications. efficiencies.
eliminate wear numerous applications. In the past, cryogenic grinding methods Not only is this change for the better,
were required on a number if applications but this is change for the better than can be
to eliminate heat elevation during proven and quantified.
More InforMatIon:
Modern Process Equipment, Inc.
3125 S Kolin Avenue
Chicago, IL 60623, USA
Tel: +1 773 254 3929
Fax: +1 773 254 3935
Web: www.mpechicago.com
20 | march - april 2010 Grain &feed millinG technoloGy PREVIOUS PAGE NEXT PAGE
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In this issue:
• Designing bagging
• Roller Mill lines to meet
• Contact the GFMT Team
Grinders
requirements
Advantages, limitations
- Specifying and
and how roller mill
designing bagging lines
grinders are changing
for the food processing
for the better
industry
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