Journal of Food Engineering 109 (2012) 603–608

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Journal of Food Engineering

journal homepage: www.elsevier.com/locate/jfoodeng

The technique and analysis of the process of separation and cleaning grain materials
Marian Panasiewicz a,⇑, Paweł Sobczak a, Jacek Mazur a, Kazimierz Zawiślak a, Dariusz Andrejko b
a
Department of Food Engineering and Machinery, University of Life Science in Lublin, Doswiadczalna 44, 20-236 Lublin, Poland
b
Department of Biological Basis Food and Feed Technology, University of Life Science in Lublin, Doswiadczalna 44, 20-236 Lublin, Poland

a r t i c l e i n f o a b s t r a c t

Article history: In the process of pneumatic separation, the aerodynamic properties of particles such as their critical
Received 5 January 2011 velocity, are used.
Received in revised form 27 September A pneumatic separator was designed that allowed a wide range of control parameters to be used.
2011
The essential factors affecting the course of the separation process were identified and a theoretical
Accepted 8 October 2011
Available online 25 October 2011
correlation between these factors and the separation efficiency were determined.
The main aim of the study was to analyse the separation process in an air stream of broken lupine
seeds, chiefly involving theoretical considerations of movement and behaviour of mixture particles in
Keywords:
Crushed mixtures
a pneumatic canal. Investigations and observations gave ground for an attempt at deriving a movement
Lupine seeds equation of particles in an unrestrained, uniform air stream.
Pneumatic separation analysis The equations obtained can be used for calculating the parameters of particle movement in pneumatic
canals. The velocities of air stream, then, can be a few times higher than the critical velocity/convection/of
individual particles. While working out the above problems the following points were considered: on the
one hand, possibilities of obtaining the greatest outcome from the separation process and on the other,
reducing the losses of valuable material in the discarded lot to a maximum.
Ó 2011 Elsevier Ltd. All rights reserved.

1. Introduction significant diversity and changeability of physical and mechanical

properties, even within the same variety. Hence a key issue is know-
An increase in cereal production and dynamic development of ing and identifying the most important factors that influence the
agricultural products creates a necessity to build modern and more course and effectiveness of the pneumatic process of separation of
efficient sorting–cleaning machines. Designing of such machines fruit-seed coat (husk) from the ground mixtures of lupines (Dziki
for particular operations which prepare the raw material for pro- and Laskowski, 2010; Roz et al., 2006).
cessing is conditioned by a number of factors, including physical
properties of the grain material, the level of cleaning accuracy, as
well as the efficiency of a technological line. At the same time 2. Pneumatic sorting–cleaning systems used in seed cleaners
the machines are to be designed keeping in mind certain require- and agricultural machines
ments such as high accuracy of sorting and cleaning, optimal
efficiency, possibility to adjust in a vast range of work parameters, One of the frequently used methods of sorting, cleaning and
and a low noise level (Reichert, 1982). segregation of various grain mixtures, as well as, agricultural and
In the process of segregation of any agricultural product a few herbal materials is the above-mentioned pneumatic separation
segregation features are sequentially applied. In case of minor (Uhl and Lamp, 1966). The segregating factor, in this case, is the
differences in segregation features between the basic material stream of air, due to variable values of the flow intensity can be
and contamination it is not indifferent which feature segregation used for initial segregation of individual components in a mixture,
will start with. One of the ways of separation and cleaning of proper cleaning and sieving or pneumatic transport.
various grain mixtures is pneumatic separation (Sosulski, 1987; In the process of pneumatic segregation aerodynamic proper-
Sosulski et al., 1987). ties of particles are used as a segregation feature, while the charac-
In the case of ground seeds of leguminous plants, processes of teristic measure is their critical velocity (lift velocity). From
separation are relatively difficult to conduct. (Day and Black, 1965; practice it is known that its value even for the same species of
Dziki and Laskowski, 2010). These materials are characterized by seeds fluctuates in a very vast range. The greater the difference
between values of critical velocities of individual components in
a mixture, the better and more efficient is the pneumatic separa-
⇑ Corresponding author. tion (Emami et al., 2007; Huang et al., 1984). What is more, the
E-mail address: marian.panasiewicz@up.lublin.pl (M. Panasiewicz). lower the critical velocity is, the lower the density and drag of a

0260-8774/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jfoodeng.2011.10.010
604 M. Panasiewicz et al. / Journal of Food Engineering 109 (2012) 603–608

particle, which in turn depend on the shape and properties of its and effectiveness of the pneumatic releasing of husks from the
surface (e.g. smooth, coarse, ribbed, mesh, covered with trichomes, remaining valuable fraction which is cotyledon (endosperm).
etc.) The method of segregation of grain mixtures with a stream of
air is used not only in specialist pneumatic chaff-removal plants
but also in more or less complex threshing and grain cleaning 4. Objective and scope
machines (Grochowicz, 1989; Johnston and Swanson, 1982). Pneu-
matic ducts are part of any universal machine for detailed cleaning The process of air separation of crushed lupine mixtures has a
and sorting of seeds, apart from the sieving unit and trieur, which certain specific character, determined by the degree of diminution,
are its main units. Together with the development of technology moisture content, and the airflow velocity in the aspiration duct of
these machines have been modified and adjusted to specific the separator. Therefore, a working hypothesis was adopted to the
requirements of the cleaning and segregation process of different effect that the above technical parameters and physical properties
seed mixtures. of mixtures had a decisive influence on the course and quality of
Pneumatic ducts can be classified depending on the process of air separation of protein from any mixture of
crushed lupine seeds.
 the direction of the stream of air (horizontal, oblique, vertical), The objective of the study was:
 the location of the fan in the system,
 the conditions of the flow of air (negative pressure, overpres-  Primary to determine the effect of selected parameters and
sure and combined conditions) (Johnston and Swanson, 1982). properties of crushed lupine mixtures on obtaining the maxi-
mum possible amount of the cotyledon fraction.
During segregation two different primary processes can be  Moreover, an attempt was made at the determination of the
applied with oblique and vertical streams of air. What is more, in relationship between the conditions under which the shelling
every schematic presented below both suction and forcing streams process was conducted and the effectiveness of separation of
of air are used (Wacker, 1989). the seed cover fraction in air at various air flow velocities.
Regardless of diverse construction solutions pneumatic systems
have a range of common additional elements which contribute to 5. Methods
more efficient and effective operation of such machines. Some of
the elements are fans, sedimentation chambers, air ducts, dust sep- The study was conducted with a view to determine the effec-
arators (cyclone separators) and sealing elements. Moreover, many tiveness of the separation process of crushed mixtures of three
factors influence precision and effectiveness of segregation of indi- lupine varieties, as lupine being the most representative of the spe-
vidual components in a mixture in all types of pneumatic separa- cies. The study was conducted for three air flow velocities; for all
tors. Following are those factors: the varieties involved, a laboratory air separation system was used.
The study was conducted on Mediterranean lupine which in-
 the characteristics of the input material (content of a mixture, cludes the annual multi-seed lupines grown in Poland. Out of each
quantity and type of contaminants), group of lupines, one variety, a representative for the species, was
 the value of differences in critical velocities between the basic selected for the study. The varieties used in the study were the
material and the contaminants, following:
 the quantity of the input mixture (the so-called load) per
surface unit of the working duct,  yellow lupine – Amulet variety,
 evenness of feeding the input material,  blue lupine – Emir variety,
 the initial velocity of the input material,  white lupine – Bardo variety.
 the velocity and evenness of the stream of air,
 time the input mixture stays in the stream of air, The materials for the study were mixtures obtained through the
 the dimensions of the pneumatic duct. crushing of seeds of three lupine varieties using a cone crusher. The
working slot width for three varieties was as follows: a1 = 2.5 mm,
Most of the above-mentioned factors usually operate compre- a2 = 3.0 mm and a3 = 4.1 mm, respectively. Out of the ground mate-
hensively thus they cannot be considered separately. It should be rial, 20 samples of 100 g each were weighed. Samples of moisture
stressed that the process of segregation of components in a mix- content of W1 = 10.1%, W2 = 12.3%, W3 = 13.8% and W4 = 15.7% were
ture using stream of air in big industrial machines is conducted subjected to air separation in the aspiration duct of the separator.
differently than in laboratory classifiers. Thus data which can be The fraction separated by the air flow was then hand sifted to sep-
found in literature on the effectiveness of pneumatic separation arate the cotyledon fraction from the fraction of seed covers with
in these two cases are often discrepant (Rovinsky, 1995; Yang cotyledon fragments. The two fractions were weighed with an
et al., 1990). accuracy of 0.01 g using an electronic balance.
That is why when selecting parameters for the process of pneu- In the next stage of the study the results obtained were used as
matic separation in each individual case both the possibility to the basis for the calculation of the index of separation effective-
achieve the highest effectiveness of separation and the lowest loss ness. The index g was determined on the basis of the following
of valuable material in the waste material have to be considered. equation:

b
3. Separation and cleaning of ground lupine seeds in an oblique g¼  100 ð1Þ
b0
stream of air
where g is the separation effectiveness index (%), b is the content of
The process of pneumatic separation of ground lupine seeds has contaminant (seed cover fraction) in the fraction separated in air
a defined specificity, conditioned by the degree of grinding, moist- flow (kg) and b0 is the content of contaminant in the input material
ness of seeds and the speed of the stream of air in the working area. (kg).
Hence it was assumed that the above-mentioned parameters and The calculated values of index g are applied in the assessment
physical properties of a mixture decisively influence the process of the effectiveness of the process of air separation of crushed grain
 M. Panasiewicz et al. / Journal of Food Engineering 109 (2012) 603–608 605

Fig. 1. Scheme of investigation stand: (1) engine; (2) wave-maker; (3) ventilator; (4) ventilator nozzle; (5) conveyor loader; (6) collective chutes; (7) loading basket. The tests
were conducted at three air flow velocities: V1 = 7.8 m s1, V2 = 10.5 m s1, and V3 = 12.8 m s1.

mixture with relation to its moisture content, degree of diminu- any single parameter of the separation process caused a decrease
tion, and air flow velocity. in the value of the separation effectiveness index. This also holds
The samples of all the grain mixtures were tested in the labora- true for an increase in the air flow velocity above the limit value
tory screen-air separator, type NSP (Fig. 1). of 12–13 m s1. While higher air flow velocities did result in an
The tests were conducted at three different air flow velocities: increase in the effectiveness of seed cover fraction separation from
V1 = 7.8 m s1, V2 = 10.5 m s1, and V3 = 12.8 m s1. the cotyledon fraction, it was at the cost of increased amounts of
the valuable fraction in the refuse. Based on the findings men-
6. Results and analysis tioned, the upper value of air flow velocity of V3 = 12.8 m s1 is
concluded be the optimum value for crushed lupine seed mixtures.
On the basis of the tests conducted by means of the air separator In the course of air separation of mixtures of the Bardo white lu-
and through manual separation of crushed seed mixture into coty- pine variety an increase in the air flow velocity from V1 = 7.8 m s1
ledon and seed cover fractions, the authors determined the index of to V2 = 10.5 m s1 resulted in an average increase in the value of
separation effectiveness g. The calculated values of the index en- the separation effectiveness index by 17–21%. In an increase in
abled the assessment of the effectiveness of air separation process the velocity from V2 = 10.5 m s1 to V3 = 12.8 m s1 the value of h
of lupine seed mixture with relation to its moisture content, degree increased more slowly, the average gain being 10–15%. It should
of diminution, and air flow velocity in the separator duct. be added here that in this case, like for the other lupine varieties,
Figs. 2–4 present the values of the separation effectiveness in- the working slot width had a distinctly lower effect on the effec-
dex, g obtained in the course of air separation process of crushed tiveness of separation than the air flow velocity.
mixtures of three lupine varieties, with relation to the moisture And thus, a change in the working slot width from a3 = 4.1 mm
content and the degree of diminution of the seeds. to a1 = 2.5 mm resulted in a 3–16% increase in the separation effec-
Analysis of the values of the separation effectiveness index, g tiveness, depending on the air flow velocity and the moisture con-
obtained indicates a relatively complex correlation describing the tent of the mixture. In the case of this lupine variety, as for the
relations among the effects of the particular parameters on the other varieties, the lowest increase in the value of the effectiveness
effectiveness of the process of air separation. A change in one of index g occurred for samples of moisture content W4 = 15.7%. Anal-
the parameters (even a slight one) leads to a considerable distur- ysis of the values of the separation effectiveness index confirmed
bance and deterioration of the process of separation, making it that the moisture content of the crushed lupine seed mixture
difficult to determine the optimum conditions for air separation had a considerable effect on the effectiveness and on the course
(Kadan et al., 1980). of the process of air separation. The highest values of the index,
And thus, the highest values of the separation effectiveness in- for all the lupine varieties tested, were obtained at moisture con-
dex were obtained in the process of air separation of crushed mix- tent W1 = 10.1% and working slot width a1 = 2.5 mm. And thus,
tures of Amulet yellow lupine. Its values were varied with relation the index g that attained the highest value for the Amulet lupine
to the moisture content of the samples, the degree of diminution, mixture was 87.2, while for the Emir and Bardo varieties the
and the air flow velocity in the separator duct. The highest value, highest values of the index were 58.2% and 68.4%, respectively.
87.2%, was obtained for a grainy mixture of a moisture content of Increasing moisture content of the mixtures brought about a
W1 = 10.1%, at a working slot width a1 = 2.5 mm and air flow veloc- noticeable decrease in the effectiveness of the process of air sepa-
ity V3 = 12.8 m s1. As the moisture content of the mixture in- ration, irrespective of the degree of diminution of the mixtures and
creased, the effectiveness of air separation of the seed cover of the air flow velocity.
fraction deteriorated distinctly. At a moisture content W4 = 15.7% While analyzing the results concerning the process of air sepa-
and a working slot width a3 = 4.1 mm, the value was only 33.1%. ration of crushed mixtures of lupine seeds, it should be stated that
The values of the index g for mixtures of the Emir lupine variety in the case of each of the varieties tested an increase in the value of
were somewhat different. In this case the highest value, 58.2%, was the effectiveness index was achieved at the cost of an increased
obtained at the working slot width a2 = 3.0 mm, air flow velocity in content of the valuable fraction (endosperm) in the refuse, which
the aspiration duct of the separator V3 = 12.8 m s1, and grain is an unfavorable and undesirable phenomenon in the process of
moisture content W1 = 10.1%. It should be noted that a change in separation of grain mixtures.
606 M. Panasiewicz et al. / Journal of Food Engineering 109 (2012) 603–608

Amulet Emir
a1=2v5 [mm] a1=2.5 [mm]
η [%] η =(0.0630)*wp2+ (8.2501)*sqrt Vs+(30.6661) η [%] η = 16.1922 W p2 + 0.0012 Vs3 + 12.6038
2
R =0.9432 R2 = 0.8968
100 105
80 90
60 75
60
40 45
20 30
0 15
0
16 80 60
12.8 16 12.8
14 60 14 45
12 10.5 12 10.5
40 30
10 7.8 10 7.8
20 15
W p [%] Vs [m s -1] W p [%] Vs [m s -1]

Amulet
Emir
a2=3.0 [mm]
a2=3.0 [mm]
η [%]
η =(13.0166) wp2+(17.1676) Vs+(0.012) η [%]
η = - 0.03318 ln W p - 0.00034 Vs3 + 0.1742
R2 = 0.9191
100 R2 = 0.8426
80 105
60 90
40 75
20 60
0 45
16 30
14 80 15
0 60
12 12.8 60 12.8
10.5 16 10.5 45
10 40 14
7.8 12 30
20 10 7.8
W p [%] -1 15
Vs [m s ]
W p [%] Vs [m s -1]
Amulet
a3=4.1 [mm] Emir
a3=4.1 [mm]
η [%] η =(13.1622)*sqrt wp+(8.40661)*sqrt Vs+(-5.3685) η [%]
R2=0.9311 η = - 0.6757 ln W p - 0.000216 Vs3 + 0.03063
R2 = 0.8653
100
80 105
60 90
40 75
20 60
45
0 30
12.8 15
16 0 12.8
14 10.5 60
12 40 16 10.5 45
10 7.8 14
20 12 30
10 7.8 15
W p [%] Vs [m s -1]
W p [%] Vs [m s -1]
Fig. 2. The value of segregation effectiveness coefficient g for ground lupine
mixtures of Amulet variety: fraction a1 = 2.5 mm, a2 = 3.0 mm, and a3 = 4.1 mm. Fig. 3. The value of segregation effectiveness coefficient g for ground lupine
mixtures of Emir variety: fraction a1 = 2.5 mm, a2 = 3.0 mm, and a3 = 4.1 mm.

7. A model for the process of separation and cleaning of grain often constitute output data in a form of numerical values, as-
mixtures of biological origin sumed in the theory of separation most often as the efficiency of
the process and the maximum amount of segregated contamina-
Before beginning the development of a model for separation tion. Often, in the processes of cleaning and separation of loose
and cleaning various grain mixtures, first one has to determine mixtures it is required that a few technological parameters are also
as many input data on the grain mixture (the subject of processing) defined, which characterize the final effect of the conducted proce-
as possible and then determine the required (expected) parameters dure. Here, an example can be the assessment of the process of
achieved after the process (output data). A very important element seed grinding from the point of view of efficiency, precision of
at this stage is to make an attempt at defining common relations ground mixtures segregation into particular grinding fractions, at
and correlations which take place between input and output data, the same time calculating and analyzing energy consumption in-
which should be treated as a basis for further modeling. A primary volved in both grinding and separation processes (sifting). Techno-
technological aim of the process of separation can be defined in dif- logical effects of the process of separation and cleaning can form a
ferent ways; hence, its final assessment can be analyzed from an database for the assessment of work of cleaning–separating
angle of various effectiveness and quality coefficients. These most machines (Salemi et al., 2010). Therefore, in order to assess the
 M. Panasiewicz et al. / Journal of Food Engineering 109 (2012) 603–608 607

Bardo the amount of i-mixture component in the output mixture desig-

a1=2.5 [mm] nated for cleaning and aii is the cleanness of i-fraction possible to
produce at full 100% separation. Eq. (2) shows the relation of actual
η [%] η = - 0.000332 W p2 - 0.008778 Vs + 0.2742 concentration gain of i-mixture component to the final, the most
R 2 = 0.8017 effective segregation.
100 As it was previously mentioned the processes of separation of
80
various grain mixtures are described by a large number of different
60
parameters are characterized by
40
20
0  applied technological models of the cleaning process,
 rules and conditions of operation of working elements in clean-
16 12.8 60 ing machines,
14 10.5
12 40  geometric dimensions and other physical characteristics of
10 7.8
20 individual components in the separated mixture,
W p [%] Vs [m s -1]  content of different contaminants in the mixture directed for
separation.
Bardo
a2=3.0 [mm] A parametric schematic of the process of separation, the most
η [%] important input and output parameters of the process, as well as
η =(13.1622)*sqrt W p+(8.40661)*sqrt Vs +(-5.3685) selected factors facilitating or disrupting the course and effective-
R 2=0.9311 ness of its operation are illustrated in Fig. 5. The input factors of the
100
80 separation process are as follows:
60
40 – the load on working elements of the cleaning machine, with ref-
20 erence to their width qw and overall surface qf;
0
– parameters related to the degree of contamination a1, a2 (con-
16 12.8 centration) of individual particles in the mixture directed for
14 separation;
12 10.5
40
10 7.8 – dimensions and shape of sieve holes si;
20
– the initial velocity of particles Vc;
W p [%] Vs [m s -1]
– the amplitude of vibration n of the frame with a set of sieves;
– the location of working element in the spatial system, defined
Bardo
by tilt angles a and b in relation to horizontal and vertical
a3=4.1 [mm]
planes;
η [%] – geometric dimensions of the pneumatic ducts: a, b, c and h
η = 0.5836 + 0.0164*W p2 - 0.0063*ln Vs
R 2=0.8632 (Mery et al., 2010).
100
80 Output parameters of the process that listed below should be
60 treated as a final effect of its effectiveness:
40
20
– pi and ci – respectively the amount of the sifted component and
0
its unsifted part;
16 12.8 – zpi and zci – the amount of unsifted material and sifted contam-
14 60
12 10.5 ination in a fraction of any direction;
40
10 7.8 – Epi and Eci – respectively the effectiveness of production of sifted
20
and unsifted fraction;
W p [%] Vs [m s -1]
– Eek – economic assessment index;
Fig. 4. The value of segregation effectiveness coefficient g for ground lupine – Een – energetic assessment index;
mixtures of Bardo variety: fraction a1 = 2.5 mm, a2 = 3.0 mm, and a3 = 4.1 mm. – Eeks – operation index;
– Eob – effectiveness of machines’ operation index;
technological effect of the process of segregation of grain mixtures
– E – comprehensive discriminant of assessment of effectiveness
of biological origin different criteria are followed. On one hand
of the separation process.
they are connected with the course and effectiveness of the sepa-
ration process itself, on the other hand with technical characteris-
Moreover, the course and effectiveness of the process of separa-
tics of a machine (or machines) which conduct the process. The
tion are also influenced by parameters describing the environment
efficiency of the process of separation Q is defined as a real sum
and conditions of its execution, which because of the specificity of
of contamination in the mixture which is directed for separation
conducting separation processes of different materials were not
Zr to the actual amount Zf of contamination produced by working
included in the above-mentioned model. A mathematical model
elements of the cleaning machine. The overall technological effect
of the process of separation should, as far as possible, meet the
of separation of the grain mixture of n-components in order to pro-
assumed aims, hence it is very important that in the initial stage
duce m different fractions can be defined by the following formula:
of its creation all parameters and factors be formulated, which will,
X
n
uii  ai to a smaller or bigger degree, influence the final effect of the
Et ¼ Wi ð2Þ process.
i¼1
aii  ai
An example of this can be defining procedures and forecast
where Wi is the amount of i-fraction, uii the cleanness of the segre- correlations, as well as, changes of selected parameters of the pro-
gated i-fraction (content of i-mixture component in i-fraction, ai cess of separation in relation to its duration (static aspect), or rela-
608 M. Panasiewicz et al. / Journal of Food Engineering 109 (2012) 603–608

Fig. 5. General parametric schematic of the process of pneumatic separation and cleaning of grain mixtures.

tions taking place while changing from one previously set rigorous References
state to another state (aspect of dynamic characteristics). That is
why all preliminary assumptions and planned main tasks of the Day, P.R., Black, C.A., 1965. Particle fraction and particle-size analysis. Methods of
soil analysis. Part I. Agronomy (ASA, Madison, WI) 9, 545–567.
model also including optimization aspects should be formulated Dziki, D., Laskowski, J., 2010. Study to analyze the influence of sprouting of the
regarding operative laws of kinetics, statistics and dynamics. wheat grain on the grinding process. Journal of Food Engineering 96 (4), 562–
567.
Emami, S., Tabil, L.G., Tyler, R.T., Crerar, W.J., 2007. Starch–protein separation from
8. Conclusions chickpea flour using a hydrocyclone. Journal of Food Engineering 82 (4), 460–
465.
(1) An increase in the moisture content of crushed lupine seeds Grochowicz, J., 1989. Study on possibility of grain pneumatic separation in the
depend of air velocity conveyance. Zeszyty Problemowe Poste˛pów Nauk
caused a considerable decrease in the value of the separation Rolniczych Zeszyt, 354 (in Polish).
effectiveness index g. With a 2% increase in moisture con- Huang, P.M., Grover, R., McKercher, R.B., 1984. Components and particle size
tent the average decrease observed in the separation effec- fractions involved in atrazine adsorption by soils. Soil Science 28, 20–24.
Johnston, P.R., Swanson, A., 1982. Correlation between the results of different
tiveness was 8.1% for yellow lupine, 7.9% for blue lupine instruments used to determine the particle size distribution in AC fine test dust.
and 2.9% for white lupine. Powder Technology 32 (1), 119–124.
(2) A decrease in the working slot width of the crusher from Kadan, R.S., Freeman, D.W., Ziegler, G.M., Spadero, J.J., 1980. Protein displacement
during classification of glanded cottonseed. Journal of Food Science 45, 1566–
a3 = 4.1 mm to a1 = 2.5 mm permitted an increase in the 1569.
effectiveness of the cotyledon fraction separation from the Mery, D., Chanona-Pérez, J.J., Soto, A., Aguilera, J.M., Cipriano, A., Veléz-Rivera, N.,
seed cover fraction by 2.1–7.7% at moisture content Arzate-Vázquez, I., Gutiérrez-López, G.F., 2010. Quality classification of corn
tortillas using computer vision. Journal of Food Engineering 101 (4), 357–364.
W1 = 10.1% and by 5.5–11.6% at moisture content
Reichert, R.D., 1982. Air classification of peas (Pisum sativum) varying widely in
W4 = 15.7%, depending on the lupine variety. protein content. Journal of Food Science 47 (4), 1263–1267, 1271.
(3) With increasing air flow velocity the separation effective- Rovinsky, L.A., 1995. Application of separation theory to hydrocyclone design.
Journal of Food Engineering 26 (2), 131–146.
ness index increased, but its increase was accompanied by
Roz, M., Rinaudo, C., Rossanigo, P., Polati, S., Gennaro, M.C., 2006. Gravitational grain
an increase in the amount of valuable fraction carried away size separation of contaminated ground: potential and limits. Applied Clay
by the air flow. With an increase in the air flow velocity Science 31, 85–89.
above V1 = 7.8 m s1 (for moisture contents within the range Salemi, E., Tessari, U., Mastrocicco, N.C.M., 2010. Improved gravitational grain size
separation method. Applied Clay Science 48 (4), 612–614.
from W1 = 10.1% to W4 = 15.7%), the highest increase in the Sosulski, F., 1987. Yield and functional properties of air classified protein and starch
value of the separation effectiveness index was recorded fractions from eight legume flours. Journal of American Chemical Society 6,
for the yellow lupines from 16.1% to 38.2%; a corresponding 363–370.
Sosulski, F., Walker, A.F., Fedec, P., Tyler, R.T., 1987. Comparison of air classification
increase in the values for the blue and white lupines from for separation of protein and starch pin-milled legume flours. Food Science and
11.3% to 22.2% and from 90% to 23.9%, respectively. Technology 20 (5), 221–225.
(4) On the basis of research results, observations and theoretical Uhl, J.B., Lamp, B.J., 1966. Pneumatic separation of grain and straw mixtures.
Transition of the American Society of Agricultural Engineers 9, 244–246.
analysis equations of particle movement in an unlimited, Wacker, P., 1989. Bekampfing von unkrautern bei der getreideernte. Fighting weeds
even stream of air were defined. They can be used to calcu- while harvesting 44. Jahrg. Landtechnik 6, 215–219.
late parameters of particle movement of individual compo- Yang, X., Bern, C., Hurburgh, C.R., 1990. Airflow resistance of cleanings removes
from corn. Transition of the American Society of Agricultural Engineers, 1299.
nents of grain mixtures in pneumatic ducts.