20 years of the Horomill – a review

20 years of the Horomill – a review*)
20 Jahre Horomill – ein Rückblick*)
1 Introduction
The Fives Group celebrates the company’s 200th anniversary
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this year, which is also the 20 anniversary of the introduction of the Horomill to the market by its subsidiary Fives
FCB. The Horomill operates on the principle of a horizontal
ring-roller mill. It was built and introduced into the
cement industry with a cylinder diameter of 2 200 mm at the
Trino cement plant in Italy that belongs to the present
Buzzi Unicem cement group. Like the vertical roller mill,
the Horomill uses the centrifugal force principle for transporting the material, for which the material cylinder is driven
above the critical rotational speed. Within a grinding plant
system the Horomill is always operated as a closed-circuit
bucket elevator mill and is used for producing raw meal and,
in particular, for grinding clinker and granulated blastfurnace
slag. It is also used in the minerals industry. As far as power
consumption is concerned the Horomill ranks between the
high-pressure roller press and the vertical roller mill. It
undoubtedly has advantages over the high-pressure roller
press that was introduced to the market in 1985. It uses
substantially lower specific grinding forces in closed-circuit
with a high performance separator and fulfils the requirements for a grinding system for producing finished ground
products.
2 The Horomill today
The Horomill was presented to the cement world for the
first time at the International VDZ Congress in 1993. In the
meantime 54 Horomills have been sold, for cement grinding
as well as for raw meal production or slag grinding (� Fig. 1).
21 Horomills were installed on the American continent, six
of them dedicated to raw material grinding, in particular the
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biggest ever designed, the HOROMILL 4400 at the Barroso
plant in Brazil. 17 Horomills are running in Europe, 11 mills for
cement grinding application. 16 Horomills were installed in
Asia, six of them dedicated to slag grinding in China, two so®
called Twin-HOROMILL plants. Two Horomills are equipped
with new single shoes, one of the latest development by FCB.
Nowadays the Horomill is operating worldwide at most of the
major cement manufacturers:
� At Buzzi Unicem that has actively participated to the
development of the mill, and whose prototype, a
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HOROMILL 2200 is still producing cement in the Trino
plant, in Italy. Buzzi Unicem now operate 18 Horomills,
including 13 mills installed in the Cementos Moctezuma
plants, Mexico, and a very recently commissioned mill
at Buzzi Unicem in Maryneal, Texas, USA.
� Five Horomills have been purchased by Holcim, and
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in particular the biggest one, the HOROMILL 4400 for
the Barroso plant, Brazil, with a production capacity of
420 t/h of raw meal.
� Cemex, Vicat are using Horomills for cement grinding in
Turkey.
� Lafarge, one of the early Horomill users with currently
three units, has recently placed an order for a mill for
cement grinding in its Teresa plant, the Philippines.
The Horomill is also an attractive technology for the Asian
cement market: four machines are operating in Vietnam and
eight machines are installed in China, where six of them are
dedicated to slag finish grinding.
3 Energy consumption and product quality
In addition to the use of the material bed compression grinding technology the process advantages of the Horomill linked
to its specific process and technical design are the following:
With a relatively low quantity of material circulating (there
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are about 10 t of material for a HOROMILL 3800) rapid and
frequent changes of product types are possible within a very
short period of about five minutes and without the need of a
purge bin to deal with intermediate production grades.
� Thanks to the material centrifugation onto the shell rotating over critical speed, combined with a large grinding
contact area, the Horomill is running stably and allows
grinding of cements with high finenesses without any
need of water spraying.
� The Horomill is not discharged by air, but only dedusted.
The ventilation is only needed for the selection circuit.
The gas circuit is then devoted 100 % to the classifier
operation with relevant cooling or drying effect. Consequently, this leads to a high saving in specific electrical
energy consumption for the fan compared to the vertical roller mill.
Figure 1: View of a small HOROMILL® 1600 from the beginning year of 1995
*) E. Edet, Fives FCB, Villeneuve d‘Ascq, France
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Hence, the energy consumed by the grinding process is low,
high quality of cement can be reached. The energy performance of the Horomill will be illustrated by some selected
industrial results in � Table 1. The Horomill leads to large
energy savings, more important with harder to grind materials, such as slag cements or pure slags. In comparison to
the classical ball mill, the energy savings are between 30 to
50 %. But also compared to other bed compression grinding
technologies, the savings can be estimated between 15 to
30 %, because the ventilation circuit is sized only for classification, and not for the material transport. In addition, it has
been measured that strength developments and values are
similar to those obtained with ball mill cements, and even
with a lower specific surface area! It also applies for both
mortar and concrete and for any cement type.
Various cement types meeting all quality targets are produced very steadily due to Horomill process stability and
TSV™ classifier proven efficiency. Some plants manufacture different types of products with the same Horomill,
taking advantage of its flexibility and versatility, with 3 to 4
daily changes of the recipe, depending on production and
sales needs like in the Karsdorf plant in Germany. For the
standard daily operation, along with the modifications of the
cement compositions, every adjustment of process parameters, and the selection of the cement silos can even be fully
automated (Trino, Italy).
below the TSV™ classifier. The classifier rejects constituting the external material circulation as a dilution for moisture, which facilitates material handling in the case of raw
mix, but also permits control of the moisture content into
the mill. The design and equipment of the grinding plant and
of its drying arrangement are selected according to the type
of material to be dried and of its grain size distribution and
moisture content.
It is important to mention that, in this way, the Horomill
eliminates two major inconveniences: high venting speed
and water spraying that leaves low operating wear rates in
the range of 0.2 to 0.7 g/t. The drying is done by feeding
the moist material into the riser duct below the classifier
(� Fig. 2). This moist material can be:
� either some wet fine component used in cement, such
as pozzolana in the Tepetzingo plant, Mexico, representing 15 % of the composition up to 24 % moisture in the
wet season, or blastfurnace slag as in the Karsdorf plant,
where up to 100 % of pure slag is fed at 10 % moisture,
� or a part of the mill outlet in the case of moist blended
cement mix up to 10 % moisture content or raw material grinding.
4 Easy management of moist materials
� Figure 3 shows the flow sheet of a plant in Tepetzingo with
a plant output in minimum of 230 t/h, where a raw mix with
a moisture of about 9 % is processed and 20 to 50 % of the
bucket elevator outlet is deviated to a flash dryer.
As the Horomill is not an air-swept mill, the drying function
is ensured in the selection gas loop, mainly in the rising duct
Whereas the fine particles are dried during their gas lifting
to the classifier, the coarsest particles are mechanically fed
Table 1: List of industrial results
Product quality
CEM I 42,5
Machine size
Capacity
[t/h]
Fineness acc. to Blaine
[cm2/g]
Spec. energy consumption [kWh/t]
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Horomill
Çimentas
3 800
76.0
2 890
18.1
27.2
3 800
103.0
3 070
18.7
24.6
Ciskovice
2 800
58.7
3 050
16.0
Karsdorf
3 800
72.6
3 860
24.5
RCC
3 600
92.0
3 260
19.9
Karsdorf
3 800
105.0
3 850
17.4
Darica
3 600
100.0
3 210
18.7
CEM II A/M (P-L)
Cerritos
3 800
115.0
3 580
15.6
CEM IV A/P
CEM II/B-P 32,5
CEM II/A-S 42,5
Tepetzingo
3 800
115.0
4 100
16.1
Mudanjang
3 800
125.5
3 360
15.1
Konya
3 800
140.0
3 100
15.4
24.2
21.9
21.2
Trino
3 800
129.0
4 920
16.1
22.2
Çimentas
3 400
81.0
4 210
18.1
25.9
Çimentas
3 400
88.6
3 880
17.3
24.2
Denizli
3 400
81.0
4 210
17.0
22.1
Denizli
3 400
83.2
4 220
16.0
21.7
Darica
3 600
106.0
4 000
17.8
HanZhong
3 800
78.0
3 330
20.5
CEM III/B 42,5
Karsdorf
3 800
63.3
4 170
28.4
Blastfurnace slags
Karsdorf
3 800
55.0
4 800
31.0
Karsdorf
3 800
57.0
4 100
28.0
Karsdorf
3 800
66.0
3 500
23.9
Tepetzingo
3 800
230.0
R90 mm < 12 %
7.9
Raw mix
Total plant
Tepetzingo
CEM II/A-L 32,5
CEM II/A-L 42,5
CEM II/A-P 3,25
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Plant size
12.3
Bag filter
Application case:
Cement and blended cements
Feed moisture up to 7 %
Outlet mill moisture < 2 %
Feed
Fan
TSV® classifier
Final
product
Reject
Hot gases supply
(HGG or cooler)
Horomill®
Aerodecantor
Bucket elevator
Figure 2: Basic flow sheet of a grinding plant with Horomill for production of cement and blended cements
Figure 4: Flow sheet of a grinding plant with Horomill, equipped with a
aerodecantor for processing of raw meal or blastfurnace slag
with high moistures
Secondary feed point
Flash dryer
Figure 3: Flow sheet of a grinding plant with Horomill, equipped with a
flash dryer for processing of raw meal, cement or blastfurnace
slag
ing pushed the start button. Thus, automatic changes of the
cement composition, adjustments of the plant parameters
and selection of the target silo have even been successfully
implemented in some plants allowing overnight and weekend operation without supervision. The external material circulation loop of the Horomill circuit also brings an advantage
with the slag grinding, and in particular in China, where the
steel industry is in expansion. The mill system gives access
to the material during the grinding process and enables performance of an in-line magnetic sorting to eliminate the
iron particles from the circulating load. So the accumulation
of coarse metallic iron inside the mill is avoided. This is an
advantage compared to other mill systems. The low ventilation inside the machine also reduces its erosion by the
wind-borne hard slag particles. Another advantage of the
external circulating load has been successfully exploited in
the minerals industry, with the extraction of specific particle size ranges.
back, either to the classifier top feeding via the bucket elevator, or to the Horomill via the classifier reject belt. Improved
drying efficiency is even obtained by the use of a so-called
aerodecantor (� Fig. 4). For example, in a plant in Jiujiang,
China, 100 % of the wet slag with a moisture of up to 12 % is
fed firstly to the aerodecantor. Only the aerodecantor coarsest particles and classifier rejects are fed to the Horomill. In The flexibility of the Horomill can be demonstrated with the
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a new plant in the Philippines, an aerodecantor will be fed Twin-HOROMILL concept (� Fig. 5). This consists of the
with wet pozzolana of 30 % of the recipe with a moisture arrangement of two mills with a single materials feed and
of up to 25 %. So moisture up to 10 % has been success- a single selection circuit using a TSV™classifier. This perfully practised in industrial plants. Trials realised in representa- mits a more compact installation, and easily adapts to the
tive tests in the Fives FCB testing station indicated that it
would be possible to process a moisture of up to 20 % without difficulty.
5 Operation stability and flexibility
The operational stability of the Horomill combined with the
well-known high-efficiency TSV™ classifier is also a major
advantage for the production of even finer cements. While
the vertical roller mill needs water addition to avoid roller
vibrations, the Horomill can keep the finished product dry.
In trials, carried out in the Fives FCB testing station under
adequate classifying conditions, high finenesses have been
reached by the production of CEM I qualities with finenesses
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according to Blaine values of more than 7 000 cm /g.
The operation of a grinding plant with a Horomill is fully
automatic, without intervention by the operator after hav-
Figure 5: View of the so-called “Twin HOROMILL®-concept”
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nology, developed by Fives FCB in the 1970s, this new patented supporting system has permitted redesigning of the
Horomill shell. As a result, it has become lighter: the shell
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of the HOROMILL 4400, dedicated to Barroso plant, has
the same weight as the shell of a four shoe supported clas®
sical HOROMILL 3800. This new configuration is already
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in operation in China, with two HOROMILL 3800, recently
commissioned for steel slag grinding.
Figure 6: View of the new hydro-dynamic single shoe bearing
variations of the production level. The grinding concept can
be operated either with one Horomill or with both, depending on the market needs. On the other hand it gives room
for better maintenance planning. This type of grinding concept is not only used for cement grinding as in Cam Pha,
Thai Nguyen, in Vietnam, but also for steel slag grinding in
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China, where two Twin-HOROMILL plants are operating in
the steel industry.
6 The Horomill – a reliable machine
The development of the Horomill was a challenge from process aspects as well as for mechanical solutions, because
the basics were adapted from proven technologies. Twenty
years after, many improvements have been carried out, making the technique mature and giving the mill a high level of
reliability. Today innovations are going on in order to answer
the evolving needs of the cement industry.
Reliability sometimes comes with simplification: The multiple supporting system of the mill cylinder with its four shoe
bearings has been replaced by a large and unique bearing
(� Fig. 6). By retaining the hydrodynamic shoe bearing tech-
With this new supporting system, larger sized machines
have been designed up to a shell diameter of 5 m,
installed with a power of 4 600 kW. In a similar manner, the
machines are equipped with compact parallel gear train
gearboxes, not only for their small size compared to standard gearboxes, but also for their high reliability and mechanical sturdiness.
A dedicated data-logging system (� Fig. 7) has been developed and was installed in a Mexican cement plant to realise
a follow-up of the evolution of the process and of the condition of some mechanical components. The tilting movement
of the roller is analysed: it gives information on the structure of the material bed and enables adaptation of the process parameters accordingly. The free rotation of the swivels
is monitored in a predictive oriented maintenance strategy
for their potential replacement, since curative maintenance
would not only reduce the global reliability of the installation
but induce side costs as well. The vibration level and the
state of the reducer bearings can also be analysed to allow
some anticipation in the control of the machine. All this contributes to increasing the availability by implementation of
predictive maintenance.
Automatic procedure and tooling for hard-welding has been
developed and implemented to compensate for the wear of
the roller sleeve and shell liner surfaces in case of high product abrasiveness (� Fig. 8). The strategy consists of maintaining the condition of their structure (rafters) to build up a
material layer on the liner surface that protects it and that
cannot slide. The maintenance
of the structure is a key point,
since the material can slide on
the hard material layer surface,
if the rafters are not sufficient.
This sliding increases the wear
rate caused by abrasion by 300
to 400 %. Assuming a regular maintenance and depending
on the abrasiveness of the
products, for cement application, a roller sleeve can last
3 to 5 years of operation, and
the liners over 8 to10 years.
Figure 7: Data logging system for monitoring the technological process and mechanical components
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For raw meal grinding, the
results vary according to the
specific abrasiveness of the
raw components, and to the
free silica content. This being
said, a sleeve can last 2 to
3 years in the case of very
abrasive products, and more
than 10 years in the case of
soft grinding materials. More
than ten years can be expected
for the shell liners.
a)
b)
Figure 8: View of the shell lining a) and roller sleeve surface b)
7 Conclusion
The Horomill is one of the latest innovations in comminution
technology, with a different design allowing compact installation with a flexible and stable operation.
With more than 50 machines in operation for the finish grinding of cement, slag, raw materials and minerals, the technology has demonstrated the expected energy efficiency and
versatility. The Horomill adapted to the coming challenges of
the market, is the right decision for the sustainability expectations of today.3
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60217
cement
international
4 processing 4 perForMAnce 4 ApplicAtion
www.verlagbt.de
no. 4/2013
Reprint from CEMENT INTERNATIONAL 11 (2013) No. 4, pp. 76–81
Verlag Bau+Technik GmbH • PO Box 12 0110 • 40601 Duesseldorf/Germany • Tel.: +49 (0) 211/9 24 99-0
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