equipment for the classification and crushing section in fertilizer

JOURNAL OF MINING AND GEOLOGICAL SCIENCES, Vol. 60, Part II, Mining, Technology and Mineral Processing, 2017
EQUIPMENT FOR THE CLASSIFICATION AND CRUSHING SECTION IN FERTILIZER
PRODUCTION
A. Norov1, D. Pagaleshkin2, A. Gribkov3, Y. Dimitrienko4, M. Zlatev5
1 PHOSAGRO
GROUP, Research Institute for Mineral Fertilizers (NIUIF), 162622 Russia, Cherepovets, ANorov@phosagro.ru
GROUP, Research Institute for Mineral Fertilizers (NIUIF), 162622 Russia, Cherepovets, DPagaleshkin@phosagro.ru
3 Apatit; Russia, Saratov district, Balakovski region, AGribkov@phosagro.ru
4 MAVEG Industrieausruestungen GmbH Moscow 123610, Russia, dimitrienko@matrading.ru
5 Head of the Sales & Project department, m.zlatev@haverniagara.com
2 PHOSAGRO
ABSTRACT. The paper includes an analysis of the most common grain-size raw material preparation schemes applicable in the mineral processing. Factors
influencing the optimal management of the crushing process are clarified and authors’ and other installations to regulate this processare presented. Based on this, a
variant for equipment for the crushing and sieving sections, tested in practice, is presented.
Keywords: sieving, crushing, fertilizer production
ɉȼɉɋɎȿȽȻɈɀ ɂȻ ȽɕɂɆɃɍɀ ɂȻ ɅɆȻɌɃɏɃɑɃɋȻɈɀ Ƀ ɋȻɂȿɋɉȼɚȽȻɈɀ ɊɋɃ ɊɋɉɃɂȽɉȿɌɍȽɉɍɉ ɈȻ ɍɉɋɉȽɀ
Ⱥɧɞɪɟɣ ɇɨɪɨɜ1, Ⱦɟɧɢɫ ɉɚɝɚɥɟɲɤɢɧ2, Ⱥɥɟɤɫɟɣ Ƚɪɢɛɤɨɜ3, ɘɪɢɣ Ⱦɢɦɢɬɪɢɟɧɤɨ4, Ɇɟɬɨɞɢ Ɂɥɚɬɟɜ5
1 ȽɊɍɉɉȺ «ɎɈɋȺȽɊɈ», ȺɈ «ɇɂɍɂɎ», 162622 Ɋɨɫɫɢɹ, ɝ.ɑɟɪɟɩɨɜɟɰ, ANorov@phosagro.ru
2 ȽɊɍɉɉȺ «ɎɈɋȺȽɊɈ», ȺɈ «ɇɂɍɂɎ», 162622 Ɋɨɫɫɢɹ, ɝ.ɑɟɪɟɩɨɜɟɰ, DPagaleshkin@phosagro.ru
3 ȺɈ «Ⱥɩɚɬɢɬ»; Ɋɭɫɢɹ, ɋɚɪɚɬɨɜɫɤɚɹ ɨɛɥɚɫɬɶ, Ȼɚɥɚɤɨɜɫɤɢɣ ɪɚɣɨɧ, AGribkov@phosagro.ru
4 ɆȺȼȿȽ Ƚɦɛɏ Ɇɨɫɤɜɚ 123610, Ɋɭɫɢɹ, dimitrienko@matrading.ru
5 Head of the Sales & Project department, m.zlatev@haverniagara.com
ɋɀɂəɇɀ. ȼ ɫɬɚɬɢɹɬɚ ɟ ɧɚɩɪɚɜɟɧ ɚɧɚɥɢɡ ɧɚ ɧɚɣ-ɱɟɫɬɨ ɫɪɟɳɚɧɢɬɟ ɫɯɟɦɢ ɡɚ ɡɴɪɧɨɦɟɬɪɢɱɧɚ ɩɨɞɝɨɬɨɜɤɚ ɧɚ ɫɭɪɨɜɢɧɢ, ɩɪɢɥɨɠɢɦɢ ɩɪɢ ɨɛɪɚɛɨɬɤɚɬɚ ɧɚ
ɦɢɧɟɪɚɥɧɢ ɫɭɪɨɜɢɧɢ. ɂɡɹɫɧɟɧɢ ɫɚ ɜɥɢɹɟɳɢɬɟ ɮɚɤɬɨɪɢ ɡɚ ɨɩɬɢɦɚɥɧɨ ɭɩɪɚɜɥɟɧɢɟ ɧɚ ɩɪɨɰɟɫɚ ɧɚ ɪɚɡɞɪɨɛɹɜɚɧɟ ɢ ɫɚ ɩɪɟɞɫɬɚɜɟɧɢ ɚɜɬɨɪɫɤɢ ɢ ɞɪɭɝɢ
ɢɧɫɬɚɥɚɰɢɢ ɡɚ ɪɟɝɭɥɢɪɚɧɟ ɧɚ ɬɨɡɢ ɩɪɨɰɟɫ. ɇɚ ɬɚɡɢ ɨɫɧɨɜɚ ɟ ɪɚɡɪɚɛɨɬɟɧ ɜɚɪɢɚɧɬ ɧɚ ɚɩɚɪɚɬɭɪɧɨ ɨɛɨɪɭɞɜɚɧɟ ɧɚ ɜɴɡɥɢɬɟ ɡɚ ɪɚɡɞɪɨɛɹɜɚɧɟ ɢ ɩɪɟɫɹɜɚɧɟ, ɤɨɣɬɨ
ɟ ɩɪɨɜɟɪɟɧ ɜ ɩɪɚɤɬɢɤɚɬɚ.
Ʌɦɹɲɩɝɣ ɟɮɧɣ: ɩɪɟɫɹɜɚɧɟ, ɪɚɡɞɪɨɛɹɜɚɧɟ, ɩɪɨɢɡɜɨɞɫɬɜɨ ɧɚ ɬɨɪɨɜɟ
Nowadays, the granulation methods, used at modern largescale fertilizer production plants, cannot guarantee the
obtaining of a product with narrow particle size distribution
range, conforming to strict requirements of standards. Thus,
any fertilizer production incorporates the classification and
crushing section. In spite of that this section is often
considered as a mechanical unit, the operation of granulation
unit and product qualitative parameters depend significantly on
it [1, 2]. Not only particle size distribution depends on it, but,
also physical and chemical properties of fertilizers, primarily,
caking and dust formation. The more fines in commercial
product, the higher value of these parameters. In paper [3], it is
specified that caking of DAP granules with size less than 2 mm
is higher by 1.8-4.4 times than caking of granules with size of
2-5 mm.
sieve screens (1st stage of classification). Further, fines and
oversized fraction (after crushing) are returned to recycle, and
product fraction is additionally classified in single or two
double-sieve screens (control classification). The part of
product fraction, conforming to load, is discharged as a final
product, another part is fed to recycle. Usually, these
processes have larger recycle ratio – from 2.5-3.0 and more.
Accordingly, the classification unit shall be suitable for such
amount of material:
In the fertilizer industry, the following granulation processes
are the most prevailing:
2. Process with drum granulator-dryer (DGD) or spherodizer.
In these units, slurry is sprayed onto granules curtain, formed
by special lifting flight. The DGD unit and spherodizer are
different, DGD has a screw for moving of internal recycle.
Usually, the processes with DGD have lower external recycle
ratio (not more than 3). Thus, in these processes, the material
‫ ܯ‬ൌ ሺͳ ൅ ܲሻ ൈ ‫ܤ‬, where
‫ – ܯ‬amount of material, which should be classified, t/h;
ܲ – recycle ratio (ratio of recycled material flow and final
product);
‫ – ܤ‬final product yield (determined by load), t/h.
1. Process with ammonizer-granulator (AG) and drying drum
(DD). In this process, after the granulation and drying, the
material is classified into three fractions in four or six double93
JOURNAL OF MINING AND GEOLOGICAL SCIENCES, Vol. 60, Part II, Mining, Technology and Mineral Processing, 2017
In paper [5], the screening process is proposed, in which the
material from DD is divided into two flows: one is classified in
standard way, and second flow is classified firstly in singlesieve screens with particle size limit of 4 mm; oversieved
product is fed for crushing and to recycle, and undersieved
product is fed partially to recycle and partially into single-sieve
screen and final product. Advantages: recycle is not classified
by lower size limit, the upper limit is artificially understated;
simultaneously, the recycled material particle size becomes
lower. Jacobs proposes the different ways of development of
classification systems for optimization of fertilizer quality [6].
is classified in less number of screens – usually, in two screens
at one stage (without control classification), but there are some
exclusions.
3. Process with granulation tower. This is the process with
the lowest recycle ratio. Here, the recycled material is
determined by removal of off-spec fractions (fines and oversize
fraction) only, i.e. granulation uniformity. Therefore, lower
classification capacity is required.
The most typical classification processes were shown,
actually, the processes are more various. For example, for the
production of flexible products like urea-based NPK, some
companies like Jacobs propose the removal of fine fraction
from the material after drying in single-sieve screens (hot
screens), further oversieved product is cooled and classified
again in double-sieve screens (cold screens) [4]. At WMC
Fertilizers factory (Australia), at DAP production plant (capacity
123-145 t/h), the three stage material classification after DD is
used: at first, in three double-sieve screens, then in four singlesieve screens, further, after cooling, in two control double-sieve
screens.
The authors of paper [7] propose the perspective process of
classification and crushing, which helps to regulate the
granulation process for changing of granules size. In this
process, material after DGD or drying drum (DD) is fed by
elevator onto two vibrating distributors, which help to distribute
the material uniformly onto vibrating screens meshes, on which
it is classified into fractions. Fine fraction from lower sieves is
fed to recycle directly – product fraction is divided into two
parts by gates with remote control: one part is fed to final
product conveyer and further, it is fed for cooling etc., another
part is fed to recycle.
Fig. 1 – Principal diagram of classification and crushing unit, allowing to regulate the granulation process
1 – DGD; 2 – elevator; 3 – recycled material belt conveyor; 4/1, 4/2 – vibrating distributor; 5/1, 5/2 – vibrating screen; 6/1, 6/2 – chain crusher; 7 – final product belt
conveyor; 8 – particle size automatic analyzer; 9/1, 9/2, 10/1, 10/2 – gate with remote control; 11 – recycled material scales.
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௅
The part of product fraction, fed to recycle, is divided in two
flows by gates with remote control, one flow is fed directly to
recycled material conveyor, and second flow is crushed in
chain crushers before being fed to recycle also. The oversize
fraction from upper sieves of screens is also fed to these chain
crushers, after crushing it is fed to recycle. The rotary speed of
chain crushers rotors (i.e. crushing intensity) and amount of
product fraction, fed for crushing, is automatically controlled by
frequency regulators and regulated gates, depending on
values of automatic particle size analyzer and based on
tendency of oversizing or fining of fraction. (Fig.1).
߬ ൌ (ɫ)
At known classification time, it is possible to calculate the
sieve length ‫ ܮ‬at given capacity ܳ (kg/s):
ܳ ൌ ‫ ܤ‬ൈ ݄ ൈ ‫ ݒ‬ൈ ߩː , where:
Using the value ‫ݒ‬, the following will be obtained:
ܳൌ
‫ݍ‬ൌ
ߟൌ
ൌ
௛ൈఘː
ఛ
(6)
, where:
(7)
ሺఉିఈሻൈሺఈିఏሻ
ఈൈሺଵିఈሻൈሺఉିఏሻ
, where:
(8)
ߙ, ߚ and ߠ – content of any fraction in initial, undersieved
and oversieved product, respectively. Classification efficiency
decreases with increasing of specific load onto sieve.
For optimal classification process, the correct selection of
amplitude and frequency of screen vibration is needed. In
vibrating screens, the effect of vibrational motions of sieve
surfaces is used for material distribution on sieve, its
transferring and loosening of caked material.
(1)
There is a certain relation between amplitude, vibration
frequency and granule size (fraction size). The higher the
fraction size is, the higher amplitude and lower frequency are.
And vice-versa, the lower the fraction size is, the lower
amplitude and higher frequency are. The relation of sieve
vibration amplitude and fraction size is shown on Figure 2.
Roughly, the screen performance may be determined by the
following methodology [10]:
On the figure it is seen that the relative low vibration
amplitude is applied for screens with direct excitation, the
fraction size of 5 mm is located at the extreme bound of their
operation.
at sieve vibration per minute ݊, the motion rate of particle on
sieve will be:
(ɦ/ɫ), where:
(5)
‫ݍ‬଴ – specific load, at which the efficiency is 0, depending on
design, operation mode of screen and size of material;
݊ – empiric coefficient, depending on flowing and adhesive
properties of product;
ߟ – total screening efficiency.
݈ – opening size;
ܽ – vibration amplitude.
଺଴
ௌ
ଵି௡ൈఎ
It is impossible to calculate precisely the performance of
inertial screens, this value is a test value. It is proportional to
sieve width, material layer height and its motion rate. It is
considered that the layer height, equal to two or three fraction
sizes, is the most preferable for classification. Vibration
frequency of inclined screen [5]:
௔ൈ୲ୟ୬ ఈൈ௡
ொ
‫ ݍ‬ൌ ‫ݍ‬଴
In accordance with these parameters, the screens should be
selected. Screen reliability is related to its long-term operation
without repair. Easiness of maintenance – firstly, it is the
accessibility of sieves for cleaning and replacing. Tightness –
the screens should not form dust.
‫ݒ‬ൌ
Specific load also depends on required efficiency of
segregation. As a result of processing of experimental data,
the following relation has been obtained [4]:
Provision of required capacity;
Provision of required quality of classification;
Operation reliability;
Easy to maintain;
Tightness.
௟
଺଴
This formula shows that, under this methodology, screen
capacity is not connected with classification quality, the general
parameter for calculation – classification time – may be
determined from experiment only.
Screens are selected on the basis of following requirements:
௔
஻ൈ௛ൈ௔ൈ୲ୟ୬ ఈൈ௡ൈఘː
Screen specific capacity ‫( ݍ‬kg/(m2×s)):
The general equipment of classification and crushing section
is screens and crushers. More often, the inertial screens are
used in fertilizer industry. They differ by number of sieves,
methods of their tension, fixing, cleaning, sealing design of
device for material distribution, sieve width etc. The significant
improvement of screen operation is achieved at usage of
material vibrating distributors.
݂ ൌ ͶͶට , where:
(4)
‫ – ܤ‬sieve width, m;
݄ – material layer height, m;
ߩː – material bulk density, kg/m3.
Such classification and crushing process allow to regulate
and stabilize the particle size of fertilizers without interference
in general process parameters. But, for implementation of such
flexible process, it is needed to have the certain crushing
capacity reserve, i.e. it is necessary to implement the aboveproposed method: 1 screen – 1 crusher.
1
2
3
4
5
(3)
௩
(2)
As written above, the most preferable height of a layer on
sieve is the height, equal to two-three fraction sizes [8]. But,
this requires a certain screen vibration amplitude.
ܽ – amplitude;
ߙ – sieve inclination angle.
At sieve length ‫( ܮ‬m), the retention time on it will be:
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Amplitude,mm
Screenwith
circumferential
vibration
Eccentricscreen
with
circumferential
vibration
Screenwith
linearvibration
Withdirect
sieveexcitation
Particlesize,mm
Fig. 2 – Diagram of relation of amplitude and fraction size
At high temperatures, the intensive tossing, loosening of
material layer occur, the large lumps of caked and adhered
material are broken. At the same time, at overrated amplitudes,
fine granules fly over the mesh and don’t pass through the
sieve. At low amplitude, the screen capacity decreases
because of insufficient shaking of material. Also, the possibility
of fouling of sieve meshes increases because the particles,
stuck in mesh, don’t get the sufficient acceleration for fly out
from mesh. It is experimentally determined that screen
operates effectively, and at this the self-cleaning from hard-toremove particles at height of material tossing [8, 10, 11]:
݄ ൒ ͲǡͶ ൈ ݈, where:
The following may be said about certain models of screens,
used in fertilizer industry. Within the course of about ten years,
within a special program, proposed to us by the German
company MavegIndustrieausr৺stungen GmbH (MAVEG), our
specialists had visited plants and studied the experience of
leading fertilizers producers in Germany, Poland, Spain,
Bulgaria, Morocco, Turkey, Jordan, Australia etc. The meetings
and consultations with leading developers of fertilizers
production technologies, like INCRO and Jacobs, were carried
out.
On the basis of this work results, the following conclusions
can be made.
(9)
݄ – material tossing height;
݈ – sixe of sieve mesh.
According to our data, screens with direct sieve excitation
(direct transferring of vibration onto classifying surface) are
reliable enough, they have high overhaul run, they doesn’t
require the monolithic platforms from reinforced concrete for
their installation (because the vibration doesn’t transfer onto
steel construction structures). However, they have certain
disadvantages. The access to lower sieves for repair and
maintenance is difficult. Also, the large screen inclination angle
decreases the classification quality. In our opinion, screens
with direct vibration transfer onto sieve surface are better for
classification of finer products (for example, feed phosphates)
than granulated fertilizers (see Figure 2).
Also, it should be considered that at constant amplitude, the
frequency cannot be increased infinitely, because, in this case,
this will result in screen wearing and decreasing of its life-time.
If the frequency is underrated, the screen capacity will
decrease.
Now, if we, with taking into account the above-mentioned,
again look at Figure 1, we will understand that screens with
direct sieve excitation are not suitable for fertilizer classification
at fraction size of 5 mm, because they have insufficient
amplitude. Also, it is seen that the most optimal parameters for
required product conform to the screens with circumferential
vibration. They are suitable for increasing of capacity of
existing and revamp requiring plants, and have the good
capacity reserve.
This type of screens has no sufficient reserve of capacity. At
relatively not high loads, screen with direct sieves excitation
may be able to solve its tasks in full manner; but, at load
increasing, the dramatic decreasing of capacity by target
product and decreasing of classification quality may happen.
It is experimentally determined that for the screens of this
type, the specific capacity of classification at 5-mm fraction
size is 12-15 t/(m2×h); at 2-mm fraction size – 3,0-4,5 t/(m2×h).
From our point of view, other types of sieves are less
suitable for fertilizer production.
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In our opinion, units with vibration at horizontal plane are not
effective and inefficient and not suitable for fertilizers
production. They are rather for flour-grinding industry.
Also, there is a doubt about the effectiveness of screens with
top axial arrangement of vibrating motors, because the
vibration from them transferred to sieve center with the help of
special closure dams (Figure 3).
Fig. 3 – Screen with top arrangement of vibrators
than 110 units of installed similar equipment in more than 40
countries around the world, give us the right to recommend the
equipment of Haver Niagara GmbH company for these
specified purposes.
As a result, the sieve central part has the high vibration
amplitude, which decreases practically down to «0» at edges
of sieve surface, this leads to non-uniformity of fertilizer
distribution along sieve width and decreases dramatically the
capacity and effectiveness of classification, and therefore, this
leads to faster wearing of sieve itself. Producers of such
screens try to compensate this disadvantage by increasing of
screens size, but, this also creates the problems with their
arrangement, layout and creates the additional loads on
construction structures. Although these screens are quite
cheap, we can’t recommend them as equipment for
classification and crushing sections of fertilizer production
plant.
The familiarization with Haver Niagara GmbH screens at
foreign and Russian fertilizer production plants convinced us in
their high reliability and efficiency, even at operation in severe
conditions, during long period of time (more than 20 years).
At revamp of phosphorous-containing fertilizers production
plant at one of the largest factory for production of this product,
JSC NIUIF specialists in the factory and MAVEG engineering
company specialists made a selection of vibrating screens for
replacement of existed old-fashioned screens GIL-52. The
Haver Niagara screens with the size of sieving surface of
2000x6000 mm (Figure 4), selected by us, were supplied to the
factory by MAVEG company, which is an authorized
representative of Haver Niagara GmbH. After replacement of
screens, the classification capacity increased significantly (up
to values 0.949 at 2 mm interface and up to 0.933 at 5 mm
interface, at DAP production), and also, this allowed (with other
measures) to increase significantly the capacity of process
lines [2, 13, 14]. This equipment proved its value, and it has
already been used for 5 years. The single disadvantage of
these screens is their insufficient tightness due to presence of
soft inserts, which requires the periodic replacement due to
their breakages during operation.
The most suitable screens for fertilizers production are
vibrating screens with circumferential vibrations, because they
have the optimal parameters, particularly, sufficient amplitude
(see Figure 2). In spite of this type of vibrating screens
requiring platforms from reinforced concrete for suppression of
vibration or special additional frames for vibration suppression
at installation, these units have high capacity and
effectiveness. As we mentioned above, on the basis of our
operational data, the specific capacity of this type of vibrating
screens (at presence of high effectiveness of classification and
provision of qualitative particle size distribution of commercial
product) is 12-15 t/(m2×h) at 5-mm fraction size, at 2-mm
fraction size – 3,0-4,5 t/(m2×h).
Theoretic calculations and studying of equipment operation
experience at similar plants, impressive reference list – more
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Fig. 4 – Haver Niagara 2000×6000 screen
Fig. 5 – Haver Niagara 1800×5000 screen
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Fig. 6 – Haver Niagara 1800×6000 screen
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Fig. 8 – Fully closed modification of Haver Niagara 1800×6000 screen
(side view)
Fig. 7 – Fully closed modification of Haver Niagara 1800×6000 screen (top
view)
In our point of view, the vibrating screens Haver Niagara
1800×6000 mm, proposed by MAVEG, as screens at first
classification stage, and screens 1800×5000 mm for control
classification, have the following advantages:
They provide the required classification quality,
including at higher capacities;
They are reliable in operation – for several years,
such units have operated successfully at fertilizer production
plants in Balakovo and Kingisepp, and also at many other
plants;
They are easy to maintain;
They are tight.
The capabilities of the mentioned companies allowed to
convert the serial equipment into equipment of individual
design with taking into account all features of the Customer’s
production areas, this allowed to reduce significantly the
possible costs for capital construction.
It is necessary to point out that it is rationally to install the
modern vibrating screens only with proper vibrating distributors
(vibrating feeders). This gives the following advantages:
The screen sieves surface is used more fully, the
material is distributed more uniformly along mesh width, as a
result of this, the capacity and effectiveness of segregation
onto fractions increase;
As a result of more uniform product distribution along
the whole width of the sieve, the wearing of its surface is more
uniform; therefore, the life time increases;
The impact load onto screen (firstly, onto vibrating
frame) decreases, as a result of this, its life time increases, and
idles decrease.
The important, and most critical criterion, for the selection of
equipment for revamp of existing plant were the capabilities of
MAVEG engineering company and the manufacturer, Haver
Niagara GmbH, for adaptation of the new equipment with
significantly higher capacity to certain conditions at the
Customer’s plant, designed earlier under the parameters of
previously used equipment with less capacity.
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happened due to their design features. This leads to failures in
feeder and screen operation, non-uniform distribution of
material onto sieves, and further, to decreasing of capacity and
effectiveness of classification. This issue may be solved by
installation of additional device for lumps removal from
vibrating feeders, as was done at one of the foreign plants
(Figure 9).
Also, the necessity of usage of vibrating feeders before
screens is proved by the specialists from fertilizer production
processes developing companies, such as Jacobs Engineering
and INCRO [12].
We analyzed the operation of vibrating feeders of different
companies. It was determined that many of them are plugged
periodically by lumps of adhered product during operation, this
Fig. 9 – Device for lumps removal from vibrating feeder
at shut-down, the crushers are not overfilled by
product, therefore, they doesn’t require the by-pass chutes and
dampers.
But, it is more rational to equip the screens with vibrating
feeders of Haver Niagara company, which do not have these
disadvantages due to their original and reliable design (Figures
10 and 11).
During the selection of equipment, we had familiarized
ourselves with the operation of chain and chain-hammer
crushers at foreign facilities (in Lithuania, Turkey, Jordan,
Morocco, Spain etc.), and the best references were obtained
from everywhere. Also, the preference to chain crushers, as
more reliable in operation and having higher capacity, is given
by lead developers of fertilizer production plants, such as
Jacobs Engineering [12] and INCRO.
Practical usage of vibrating feeders shows that, for provision
of stable operation of classification unit, it is needed to provide
some reserve of vibrating distributors capacity: for a screen
with classification capacity of 150 t/h at 5-mm fraction size, the
vibrating distributor shall have capacity of 200 t/h, for a
vibrating screen with capacity of 100 t/h – 150 t/h.
Particular attention shall be paid to crushing equipment at
classification unit arrangement. The detailed study of usage of
different equipment for these purposes at many plants around
the world allowed us to give preference to the proposed by
MAVEG chain crushers with capacity of 50 t/h, made by Sulta
company, with taking into account the solved tasks on
increasing of production capacities (Figure 12). Some years
ago, together with the specialists from a large plant and
MAVEG company, which is the authorized representative of
Sulta company, we selected this equipment for phosphorouscontaining fertilizer production plant. Since then, more than 5
years have been passed, and they have been operating at all
process lines. The main advantages of equipment of this type
are:
operational reliability;
efficiency;
easiness in maintenance and repair;
this type of crushers gives the highest yield of grain
fraction from 0.5 up to 2,0 mm (it is the germs for granules
formation) and less dust fraction at crushing;
with the frequency regulators, it is easy and
convenient to change intensity and thinness of crushing;
Below, the Sulta comparative data on particle size
distribution of product, obtained after crushing in chain and
chain-hammer crushers, is specified. The company provides
the possible content of fractions, critical for production, more
than 3 mm and less than 1 and 3 mm (Table 1).
For fertilizer production, Sulta company recommends the
use of chain crushers, for feed phosphates – chain-hammer
crushers.
During crushing of fertilizer large-size fraction, it is rational to
obtain «grains» – particles of size from 0,5 up to 2,0 mm,
which are the “germs” of granules at granulation process in AG
or DGD. Finer, dusty fraction is of significantly less interest for
granules obtaining, the most part of it flows to the gas
scrubbing system, increasing the density of absorbing liquid
and mole ratio NH4/H3PO4 in it, complicating water balance;
this results in decreasing the capacity of the process line and
worsening of the gas scrubbing.
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JOURNAL OF MINING AND GEOLOGICAL SCIENCES, Vol. 60, Part II, Mining, Technology and Mineral Processing, 2017
Fig. 10 – Vibrating distributor «Haver&Boecker»
Fig. 11 – Diagram of flows in feeder «Haver&Boecker»
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JOURNAL OF MINING AND GEOLOGICAL SCIENCES, Vol. 60, Part II, Mining, Technology and Mineral Processing, 2017
Fig. 12 – Sulta chain crusher with capacity of 50 t/h
Table 1.
Characteristics of chain and chain-hammer crushers of Sulta company
Parameter
Crusher MODEL 604-W36-C
Ite
m No.
Chain
1
2
3
Chain-hammer
Particle size distribution of loaded product, %
>20 mm (max.)
10
10
>10 mm (max.)
20
20
>4 mm
100
100
Particle size distribution of unloaded product, %
MAP/DAP
NPK
MAP/DAP
NPK
>3 mm
20-35
30-45
15-30
25-40
<3 mm
80-65
70-75
85-70
75-60
<1 mm (max.)
10
5
12
8
Design capacity, t/h
50
Examination, made after phosphorous-containing fertilizer
production plant revamp at one of the largest facilities in
Russia [2, 13, 14], showed that particle size distribution values
at crushers outlets were close to the shown in Table 1. The
content of fractions less than 0.5 mm and less than 1.0 mm
decreased more than 2 times as a result of usage of the
mentioned crushers. Other types of crushers give worse
results.
50
After crushing, the hammer crushers give the significant
amount of fine fraction (dust) and non-crushed product lumps,
passed through the crusher.
Three-roll crushers also form mush dust at crushing; and in
case of using of more flexible products, they may even form
the plates (“cakes”) of pressed fertilizers.
The examination also proved the possibility of crushing
process regulation with frequency regulators: at changing the
rotating speed, the intensity and thinness of crushing change.
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JOURNAL OF MINING AND GEOLOGICAL SCIENCES, Vol. 60, Part II, Mining, Technology and Mineral Processing, 2017
6 Van Nguyen. The evolution of screening systems for
optimum fertilizer product quality. SYMPHOS Conference
2013.
7 Patent of Russian Federation No. RU2545328. The method
of regulation of phosphorous-containing fertilizers
granulation process/B.V. Levin, I.G. Grishaev, A.M. Norov,
D.A. Pagaleshkin, A.S. Malyavin, A.B. Gribkov, published
in 27.03.2017.
8 P.V. Klassen, I.G. Grishaev. General fertilizers production
processes // Khimiya. – Ɇ., 1990;
9 M.B. Generalov and others. Design of equipment for
fertilizers granulation //Mashinostroyenie. – Ɇ., 1984;
10 P.V. Klassen, I.G. Grishaev, I.P. Shomin. Granulation //
Khimiya – Ɇ., 1991;
11 P.M. Sidenko. Crushing in chemical industry // Khimiya. –
M., 1977;
12 M.J. Bowness and D.M. Ivell, Jacobs Engineering, USA.
Granulation plant revamps – methodology and design
options. IFA Technical Conference. Chennai, India,
September 24-27, 2002;
13 V.V. Davydenko, A.M. Norov, I.G. Grishaev, A.S. Malyavin
and others. Experience of technical re-equipment of
fertilizing ammonium phosphates production plant at OOO
Balakovo Mineral Fertilizers. Bulletin “World of sulphur, N,
P and K”. Ɇ., OJSC NIUIF, issue No. 2, 2011.
14 Y.D. Chernenko, A.M. Norov., I.G. Grishaev, A.S. Malyavin
and others. Possibilities of intensification of complex
phosphorous-containing fertilizers. Chemical technics, No.
10, 2011.
We can conclude that our proposed option of equipment for
classification and crushing sections at fertilizer production
plants has been proved in practice and is worth serious
attention.
References
1 I.G. Grishaev. New developments in equipment and process
of phosphorous-containing fertilizers production //NIUIF
proceedings. – Ɇ., 2014. p. 375-382;
2 A.M. Norov, A.S. Malyavin, M.N. Tcikin. Modernization and
development of complex phosphorous-containing fertilizers
production. In collection “Modern trends in production and
usage of phosphorous-containing fertilizers and nonorganic acids”. Materials of International scientific and
practical conference, May, 26, 2015, Moscow //JSC NIUIF.
– Ɇ., 2015. p. 12-25;
3 A.M. Norov, A.S. Malyavin, K.N. Ovchinnikova., V.V. Sokolov
and others. Development of norms of optimal process
mode for production of granulated diammonium phosphate
from non-concentrated wet phosphoric acid // Chemical
technology. 2012. No.11. vol. 13. p. 641-647;
4 D.M. Ivell. Method of production of urea-based NPKfertilizers. Paper of IFA Technical Conference. April, 2004,
Beijing, China.
5 I.G. Grishaev, A.A. Gordin. Improvement of classification and
crushing unit at ammonium phosphates production with
usage the process with ammonizer-granulator. Bulletin
“World of sulphur, N, P and K”, Ɇ., OJSC NIUIF, issue 4,
2008.
This article was reviewed by Assoc. Prof. Dr. Pavel Pavlov and Prof. Dr.
Nikolay Jechev.
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