Destruction of microparticles related to dusty plasma processes and possible technological applications
A method of destruction of microparticles related to dusty plasma processes is discussed. The method includes the achievement of anomalously high dust particle charges, for which the destruction process of the particles starts. Technological applications of dust particle destruction can be associate...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2012
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irk-123456789-1091092016-11-21T03:02:43Z Destruction of microparticles related to dusty plasma processes and possible technological applications Morozova, T.I. Kopnin, S.I. Popel, S.I. Фундаментальная физика плазмы A method of destruction of microparticles related to dusty plasma processes is discussed. The method includes the achievement of anomalously high dust particle charges, for which the destruction process of the particles starts. Technological applications of dust particle destruction can be associated with the separation of nano- and microscale monomineral fractions from polymineral microparticles, that is of practical interest for enhancement of the efficiency of development of low-grade deposits and reprocessing of ore dumps and tailings which contain a definite amount of noble metals in the form of fine-dispersed fractions. Обсуждается метод дробления микрочастиц в плазменно-пылевых процессах. Метод включает достижение аномально высоких зарядов пылевых частиц, при которых начинается их разрушение. Технологическое применение разрушения частиц может быть связано с разделением полиминеральных частиц на нано- и микромасштабные мономинеральные фракции, что представляет практический интерес с точки зрения повышения эффективности разработки рудных месторождений и переработки рудных отвалов и хвостохранилищ, содержащих определенное количество благородных металлов в виде тонковкрапленных фракций. Обговорюється метод дроблення мікрочастинок в плазмово-пилових процесах. Метод включає досягнення аномально високих зарядів пилових частинок, при яких починається їх руйнування. Технологічне застосування руйнування частинок може бути пов'язано з поділом полімінеральних частинок на нано- і мікромасштабні мономінеральні фракції, що представляє практичний інтерес з точки зору підвищення ефективності розробки рудних родовищ і переробки рудних відвалів і хвостосховищ, що містять певну кількість благородних металів у вигляді тонковкраплених фракцій. 2012 Article Destruction of microparticles related to dusty plasma processes and possible technological applications / T.I. Morozova, S.I. Kopnin, S.I. Popel // Вопросы атомной науки и техники. — 2012. — № 6. — С. 84-86. — Бібліогр.: 3 назв. — англ. 1562-6016 PACS: 52.27.Lw, 81.07.-b, 62.25.-g http://dspace.nbuv.gov.ua/handle/123456789/109109 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Фундаментальная физика плазмы Фундаментальная физика плазмы |
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Фундаментальная физика плазмы Фундаментальная физика плазмы Morozova, T.I. Kopnin, S.I. Popel, S.I. Destruction of microparticles related to dusty plasma processes and possible technological applications Вопросы атомной науки и техники |
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A method of destruction of microparticles related to dusty plasma processes is discussed. The method includes the achievement of anomalously high dust particle charges, for which the destruction process of the particles starts. Technological applications of dust particle destruction can be associated with the separation of nano- and microscale monomineral fractions from polymineral microparticles, that is of practical interest for enhancement of the efficiency of development of low-grade deposits and reprocessing of ore dumps and tailings which contain a definite amount of noble metals in the form of fine-dispersed fractions. |
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Article |
| author |
Morozova, T.I. Kopnin, S.I. Popel, S.I. |
| author_facet |
Morozova, T.I. Kopnin, S.I. Popel, S.I. |
| author_sort |
Morozova, T.I. |
| title |
Destruction of microparticles related to dusty plasma processes and possible technological applications |
| title_short |
Destruction of microparticles related to dusty plasma processes and possible technological applications |
| title_full |
Destruction of microparticles related to dusty plasma processes and possible technological applications |
| title_fullStr |
Destruction of microparticles related to dusty plasma processes and possible technological applications |
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Destruction of microparticles related to dusty plasma processes and possible technological applications |
| title_sort |
destruction of microparticles related to dusty plasma processes and possible technological applications |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2012 |
| topic_facet |
Фундаментальная физика плазмы |
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http://dspace.nbuv.gov.ua/handle/123456789/109109 |
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Destruction of microparticles related to dusty plasma processes and possible technological applications / T.I. Morozova, S.I. Kopnin, S.I. Popel // Вопросы атомной науки и техники. — 2012. — № 6. — С. 84-86. — Бібліогр.: 3 назв. — англ. |
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Вопросы атомной науки и техники |
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84 ISSN 1562-6016. ВАНТ. 2012. №6(82)
DESTRUCTION OF MICROPARTICLES RELATED TO DUSTY PLASMA
PROCESSES AND POSSIBLE TECHNOLOGICAL APPLICATIONS
T.I. Morozova
1,2, S.I. Kopnin1,2, S.I. Popel1,2
1Institute for Dynamics of Geospheres RAS, Moscow, Russia;
2Moscow Institute of Physics and Technology, Moscow, Russia
A method of destruction of microparticles related to dusty plasma processes is discussed. The method includes
the achievement of anomalously high dust particle charges, for which the destruction process of the particles starts.
Technological applications of dust particle destruction can be associated with the separation of nano- and microscale
monomineral fractions from polymineral microparticles, that is of practical interest for enhancement of the
efficiency of development of low-grade deposits and reprocessing of ore dumps and tailings which contain a definite
amount of noble metals in the form of fine-dispersed fractions.
PACS: 52.27.Lw, 81.07.-b, 62.25.-g
INTRODUCTION
Dust particles are found in interstellar medium, in
magnetospheres and ionospheres of planets, in cometary
atmospheres, etc. Influence of dust on the properties of
the matter is often significant and sometimes
determinative. Laboratory experiments on dusty
plasmas are carried out beginning from 1990s. Since
then understanding of the processes in dusty plasmas is
improved significantly. An important topic of
investigations related to dusty plasmas is the
consideration of possible technological applications of
dusty plasma methods. In this paper we discuss a
possibility of the use of dusty plasma methods for
destruction of dust particles, which can be utilized for
processing of noble metal ore from particular deposits.
The exhaustion of high-grade deposits in the process
of mining and production of noble metals demands
enhancement of the efficiency of development of low-
grade deposits and reprocessing of ore dumps and
tailings, which contain a certain amount of noble metals
in the form of finely disseminated fractions. The
recovery of disseminated metals from fractions which
are less than 100 µm in size is a complicated problem.
Here, we present an attempt to solve this problem using
dusty plasma methods.
1. ELECTROSTATIC PRESSURE
In a plasma dust particles acquire often high electric
charges q eZd d= . Here, e− is the electron charge. In
experiments [1] the charges of about 5·107e are
observed. Under the assumption of spherical form of a
dust particle of the size a and homogeneous distribution
of the charge over its surface, the electrostatic pressure
which acts on the dust particle surface is
2
1 2
4
8
e
P Zd
aπ
= . (1)
When the electrostatic pressure (1) is higher than the
strength σ of the particle, then the particle destroys.
Furthermore, in the case of polymineral particles [2]
their separation to monomineral fractions is possible.
The conditions for the dust particle destruction can
be satisfied when dusty plasma is formed by the action
of high-powered ultraviolet radiation or X-rays. In this
case the photoelectric effect plays an important role in
the dust particle charging process resulting in positive
charges of dusts. Possible sources of such hard radiation
are synchrotron radiation, laser-electron generators, etc.
2. BASIC EQUATIONS
Dynamics of dust particle charge in plasma medium
is described by the equation
( )qd I qd
t
∂
=
∂
, (2)
where I(qd) is the total current which is represented by a
sum of microscopic electron and ion currents, as well as
the photoelectron current. Photoelectrons are generated
as a result of photoelectric effect when electromagnetic
radiation interacts with the surface of the particle.
For simplicity, we consider a situation when the
plasma consists of positively charged dust particles and
photoelectrons. Such a situation can be realized in
vacuum chamber (Fig. 1) where dust particles are
injected by means of dispenser. Walls of vacuum
chamber are supposed to be transparent for UV-
radiation and X-rays.
Fig. 1. Installation for destruction of microparticles by
dusty plasma methods
Dust particles sediment under the action of the
gravity, are irradiated by hard photons which knock out
electrons from the surfaces of dust particles, and finally
ISSN 1562-6016. ВАНТ. 2012. №6(82) 85
acquire positive charges due to the action of hard
electromagnetic (UV and X-ray) radiation.
In this situation the steady-state charge on the
particle surface is defined by the equation
( ) ( ) 0,I q I qph d eph d+ = (3)
where photoelectron current to dust particle (return
current) is
2
82
( ) 1
Z eTe dI q n eZ aeph d d d
m aTe e
π
π
= − +
⎛ ⎞
⎜ ⎟
⎝ ⎠
, (4)
while the current of the photoelectrons which leave
particle surface is
( ) ( )
( ){ }
max2
max , min
I q a e j dph d pheq aR d
ω
βπ ω ω
ω ω
= ∫
+ h
. (5)
Here, dn is the number density of dust particles, Te is
the electron temperature, me is the electron mass,
( )j ph ω is the spectral density of electromagnetic
radiation flux, maxω ( minω ) is the upper (lower)
boundary of the spectrum of electromagnetic radiation,
Rω is the work function of dust matter, β is the
probability to knock out electron by photon from
particle surface, h is the Plank’s constant.
Taking in the consideration Eqs. (4) and (5) we
rewrite Eq. (3) in the form
2
2 8 1 0.d e d
ph d d
e e
Z T Z ea j n Z
t m aT
π β
π
⎡ ⎤⎛ ⎞∂
= < > − + =⎢ ⎥⎜ ⎟∂ ⎝ ⎠⎣ ⎦
(6)
Here, ( )
( ){ }
max
max , mineq aR d
j j dph ph
ω
ω ω
ω ω
+
= ∫
h
.
Finally, we find a solution of Eq. (6) which corresponds
to positive particle charge
( )2
41
1 1 .2
2 8
e aT jaT e pheZd
e n T me ed
β
π
< >
= + −
⎛ ⎞⎛ ⎞⎜ ⎟⎜ ⎟⎜ ⎟⎝ ⎠⎝ ⎠
(7)
3. DUST PARTICLE DESTRUCTION
Condition for dust particle destruction (coincident
with the condition of polymineral particle separation to
monomineral fractions) can be found from Eqs. (1) and
(7). It takes the form
3
16 2
j T me eph
a nd
β
πσ
< >
< . (8)
Further calculations are performed under the
assumption that the main dust particle component part is
quartz. This assumption presents a practical interest for
gold-bearing ores of concrete deposits [2]. For such
particles the strength σ is equal approximately to
90 kbar.
Fig. 2 shows the minimum density of
electromagnetic radiation flux required for dust particle
destruction in dependence on particle radius. The typical
parameters are chosen to be Te = 1 eV, 0.1β = , σ ≈
90 kbar.
Fig. 2. Minimum radiation flux density required for
particle destruction vs particle radius for different
values of dust number density
A possibility of polymineral particle destruction and
its separation to monomineral fractions is estimated on
the basis of Eq. (8). For the estimates we use the
parameters of synchrotron radiation generated on
VEPP-3 electron-positron storage ring at the Budker
Institute of Nuclear Physics, where the flux density of
synchrotron radiation from viggler with the magnetic
field 2 Т, electron energy 2 GeV, and current 100 mA at
the distance of 20 m from the source is higher than
1012 photon/mm2·s [3]. The average energy of radiation
is close to 20 keV. Correspondingly, at less distances
from the source one can expect much more intensive
electromagnetic radiation flux. For instance, at the
distance of 20 cm from the source the flux density of
synchrotron radiation reaches the magnitudes higher
than 1016 photon/mm2·s. This value is used in further
calculations. The other parameters are Te = 1 eV,
0.1β = , σ ≈ 90 kbar.
Using Eq. (8) one can find that the destruction of
quartz particles with sizes less or equal to 1 µm occurs
for nd
< 10-3
сm-3, with sizes less or equal to 100 nm for
nd
< 1 сm-3, and with sizes less or equal to10 nm for
nd < 103
сm-3. Thus we show a possibility of dust
particle destruction (and its possible separation to
monomineral fractions in the case of polymineral dust
particles) by dusty plasma methods.
Fig. 3 illustrates charges of dust particles for
different values of dust number densities in the presence
of synchrotron radiation flux with the density of
1016 photon/mm2·s. It is seen that the charges of micron-
sized particles can reach the magnitudes exceeding 107
elementary charges. Such large dust particle charges
can be achieved only for small dust number densitites.
For larger dust number densities the effect of strong
dust particle charging can be achieved if a method of
removal of electrons from the vacuum chamber will be
proposed. The electrons formed in the vacuum chamber
due to the photoelectric effect on dust particle surfaces
prevent strong dust particle charging, because they tend
86 ISSN 1562-6016. ВАНТ. 2012. №6(82)
to return to the dust particle surfaces in the form of
microscopic electron currents.
Fig. 3. Charge number Z
d
vs dust particle radius.
Radiation flux density is equal to 1016 photon/mm2·s
CONCLUSIONS
Thus, we have considered a possibility of
destruction of dust particles and their separation to
monomineral fractions by dusty plasma methods. These
processes can be accomplished in vacuum chamber
where dust particles are injected.
The destruction effect can be achieved with
anomalously high dust particle charging due to
irradiation of dusts by hard and intensive
electromagnetic radiation (UV and X-rays) performed
with the aid of modern installations. This problem and
its further technological elaboration present practical
interest for enhancement of the efficiency of
development of low-grade deposits and reprocessing of
ore dumps and tailings.
This work is supported by the Division of Earth
Sciences of the Russian Academy of Sciences (the basic
research program № 5 "Nanoscale particles: conditions
of formation, methods of analysis and recovery from
mineral raw").
REFERENCES
1. M.N. Vasil’ev, N.A. Vorona, et al. Anomalously high
charging of dispersed particles by 25-keV electron
beam// Technical Physics Letters. 2010, v. 36, № 2,
p. 1143-1145.
2. V.V. Adushkin, S.N. Andreev, S.I. Popel. Cavitation
separation of nano- and microscale monomineral
fractions from polymineral microparticles // Geology of
Ore Deposits. 2007, v. 49, № 3, p. 201-207.
3. V.M. Aulchenko, O.V. Evdokov, et al. A Detector for
imaging of explosions on a synchrotron radiation beam//
Instruments and Experimental Techniques. 2010, v. 53,
№ 3, p. 334-349.
Article received 19.09.12
ДРОБЛЕНИЕ МИКРОЧАСТИЦ В ПЛАЗМЕННО-ПЫЛЕВЫХ ПРОЦЕССАХ И ВОЗМОЖНЫЕ
ТЕХНОЛОГИЧЕСКИЕ ПРИМЕНЕНИЯ
Т.И. Морозова, С.И. Копнин, С.И. Попель
Обсуждается метод дробления микрочастиц в плазменно-пылевых процессах. Метод включает
достижение аномально высоких зарядов пылевых частиц, при которых начинается их разрушение.
Технологическое применение разрушения частиц может быть связано с разделением полиминеральных
частиц на нано- и микромасштабные мономинеральные фракции, что представляет практический интерес с
точки зрения повышения эффективности разработки рудных месторождений и переработки рудных отвалов
и хвостохранилищ, содержащих определенное количество благородных металлов в виде тонковкрапленных
фракций.
ДРОБЛЕННЯ МІКРОЧАСТИНОК У ПЛАЗМОВО-ПИЛОВИХ ПРОЦЕСАХ І МОЖЛИВІ
ТЕХНОЛОГІЧНІ ЗАСТОСУВАННЯ
Т.І. Морозова, С.І. Копнін, С.І. Попель
Обговорюється метод дроблення мікрочастинок в плазмово-пилових процесах. Метод включає
досягнення аномально високих зарядів пилових частинок, при яких починається їх руйнування.
Технологічне застосування руйнування частинок може бути пов'язано з поділом полімінеральних частинок
на нано- і мікромасштабні мономінеральні фракції, що представляє практичний інтерес з точки зору
підвищення ефективності розробки рудних родовищ і переробки рудних відвалів і хвостосховищ, що
містять певну кількість благородних металів у вигляді тонковкраплених фракцій.
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