Nuclear-physical methods of analysis of noble metals and rare-earth elements
A summary of the analysis noble and rare metals by combined methods is presented. The electrodeposition of gold at a carbon film and Rutherford backscattering was used for determination its in ores. The sorbents and particle induced X-ray emission was used for determination rare and noble metals in...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2001 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Цитувати: | Nuclear-physical methods of analysis of noble metals and rare-earth elements / N.P. Dikiy, V.I. Borovlev, V.D. Zabolotny, Yu.V. Lyashko, Y.P. Medvedeva, R.P. Slabospitsky, I.D. Fedorets, N.A. Shlyakhov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 81-83. — Бібліогр.: 6 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860084750229700608 |
|---|---|
| author | Dikiy, N.P. Borovlev, V.I. Zabolotny, V.D. Lyashko, Yu.V. Medvedeva, Y.P. Slabospitsky, R.P. Fedorets, I.D. Shlyakhov, N.A. |
| author_facet | Dikiy, N.P. Borovlev, V.I. Zabolotny, V.D. Lyashko, Yu.V. Medvedeva, Y.P. Slabospitsky, R.P. Fedorets, I.D. Shlyakhov, N.A. |
| citation_txt | Nuclear-physical methods of analysis of noble metals and rare-earth elements / N.P. Dikiy, V.I. Borovlev, V.D. Zabolotny, Yu.V. Lyashko, Y.P. Medvedeva, R.P. Slabospitsky, I.D. Fedorets, N.A. Shlyakhov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 81-83. — Бібліогр.: 6 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | A summary of the analysis noble and rare metals by combined methods is presented. The electrodeposition of gold at a carbon film and Rutherford backscattering was used for determination its in ores. The sorbents and particle induced X-ray emission was used for determination rare and noble metals in ores. The minimum detectable concentration for ores was 0.1 mg/g.
|
| first_indexed | 2025-12-07T17:18:54Z |
| format | Article |
| fulltext |
NUCLEAR-PHYSICAL METHODS OF ANALYSIS OF NOBLE
METALS AND RARE-EARTH ELEMENTS
N.P. Dikiy, V.I. Borovlev, V.D. Zabolotny, Yu.V. Lyashko, Y.P. Medvedeva,
R.P. Slabospitsky, I.D. Fedorets, N.A. Shlyahov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
A summary of the analysis noble and rare metals by combined methods is presented. The electrodeposition of
gold at a carbon film and Rutherford backscattering was used for determination its in ores. The sorbents and particle
induced X-ray emission was used for determination rare and noble metals in ores. The minimum detectable concen-
tration for ores was 0.1 µg/g.
PACS: 87.58.Ji.
Development of a new method of analysing all met-
als in the noble metals group and rare-earth elements is
a matter of considerable interest. Combined methods re-
ducing minimum detectable concentration and extend-
ing significantly the field of application were imple-
mented in electrostatic accelerators NSC KPTI.
DETERMINATION OF GOLD CONTENT
OF ORES BY THE RUTHERFORD
BACKSCATTERING (RBS) OF HELIUM
IONS
The essence of the method lies in analysing the tar-
gets obtained by electrodeposition of gold at a carbon
base using elastic scattering of accelerated particles. In
this case, the energy of scattered ions Е1 is expressed in
the following way:
Е1 = Е0{[М2
2- М1
2 sin2θ)1/2 + М1 cosθ]/(М2+ М1)}2,
where Е0 − energy of incident particle, М1, М2 – masses
of the incident particle and target nucleus, θ − scattering
angle of the particle with a mass of М1. In our case (a
thin target of the substance being determined) the en-
ergy of scattered particles for a set detection angle will
correspond to the atomic weight of elements. Scattering
cross-section σ(θ):
σ(θ) = (Z1 Z2 e2/E)2 (1/sin4θ/2),
where Z1, Z2 – charges of the incident particle and target
nucleus. The yield Qd of particles registered by the de-
tector is expressed:
Qd = σ(θ) Ω Q Nm,
where Ω - detector solid capture angle, Q – number of
incident ions, Nm – number of atoms per cm2. The min-
imum value Nm , which could be detected with the help
of RBS [1] is:
Nm = (Qd Y/σ(θ) dΩ a) ½,
where Y – scattering products yield, a – area of the
beam spot. When using helium ions with Е0 = 2 MeV,
θ = 1600, dΩ = 2 10-2 Sr, Y = 10-3, а = 0.1 cm2, with the
minimum detection number being equal to 100 (error =
10%), the thickness of the layer for gold is
1012 atoms/cm2 or 0.3 ng/cm2. Experience shows that the
minimum detectable number for gold is 5 1011
atoms/cm2. When using annular semiconductor detect-
ors, the minimum detectable number can reach 1011
atoms/cm2.
Fig. 1 shows a typical RBS spectrum for helium ions
with energy of 2.87 MeV at carbon target after 30 µg of
gold were deposited in electrolyses. The dose of helium
ions was 30 µCl. Energy resolution of the semiconduct-
or detector was 28 keV for alpha-particles with an en-
ergy of 5 MeV. The number of counts in peak is
50 ÷ 100 counts from 1 µg of gold per µCl. The energy
of helium ions was picked to satisfy the condition that
the relation of counts in gold peak to total number of
counts from carbon should be maximum. It is practic-
ally impossible to separate platinum, osmium, iridium
and gold. Therefore, gold detection selectivity was
achieved by choosing an optimum electrolysis voltage
and electrolysis composition.
Gold was concentrated by electrolysis in a quartz
cell, with the anode made of the special spectrally pure
graphite and the cathode of pyrolytic graphite (total im-
purities content is less than 1 ppm) [2]. Solution
НCl + HNO3 at рН = 2 was used as electrolyte. Condi-
tions of electrolysis: voltage 0.76 - 0.9 V, current
strength 0.006 - 0.03 mA, target area – 1 cm2, electro-
lysis time – 60 minutes. The standard curve was ob-
tained by method of addition [2].
To analyse the gold content of ore, the sample was
decomposed [3] depending on its constitution. When
gold content of water is analysed, gold can be deposited
directly after the sample with a volume of 200-500 ml
was brought to рН = 2 [4].
DETERMINATION OF NOBLE METALS
USING THE METHOD OF PARTICLE IN-
DUCED X-RAY EMISSION (PIXE)
The method of PIXE induced by accelerated parti-
cles possesses more universal characteristics for the
purposes of elemental analysis. It analyses the source
200 400 600 800
channels
0
1000
2000
3000
co
un
ts
Au
C
Fig. 1. Backscattering spectrum of helium ions with
energy 2.87 MeV from a carbon target
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2001, № 1.
Series: Nuclear Physics Investigations (37), p. 81-83.
81
matrix and detects 10 - 15 elements simultaneously. The
advantages of the PIXE analysis are especially pro-
nounced when detecting the whole group of noble
metals using sorbents. Ore samples can be decomposed
and sorbed in field conditions or at a mine, and meas-
urement can be done in laboratory with the help of Van
Graaff accelerator. The sorbents containing low-Z ele-
ments should preferably be used. This suggests a low
level of background braking radiation and PIXE by
sorbent atoms (activated carbon, silica-based sorbents, etc.).
The method of proton-induced PIXE with the energy
of protons 2 - 3 MeV combination with the use of sorb-
ents produced the lowest minimum detectable concen-
tration when the analysis fell into the following pattern:
sample decomposition, sorption, desorption of noble
metals by thiourea and their electrodeposition at carbon
base followed by analysis using Si(Li)-detector.
НCl + HNO3 solution doped with acetic acid and invest-
igated thiourea sample with noble metals was subjected
to electrolysis.
0.01 0.10 1.00 10.00
content of Au ( g on 0.25 ml)
0.10
1.00
10.00
100.00
ra
di
at
io
n
(y
ie
ld
o
n
C
i)
ju
vl
1 2
3
4
5
µ
µ
Fig. 2. Dependence of yield of X-rays on gold for vari-
ous requirements of a cathode, deposition at pH=0.6:
1 − HCl+HNO3+CH3COOH U=5.0 v,
2 − HCl+HNO3+CH3COOH+SC(NH2)2 U=5.0 v,
3 − HCl+HNO3+CH3COOH+SC(NH2)2 U=4.0 v,
4 − HCl+HNO3+CH3COOH+SC(NH2)2 U=2.6 v,
5 − HCl+HNO3+SC(NH2)2 U=1.1 v
The final analysis was carried out using Van Graaff
accelerator with a Si(Li)-detector with the energy resol-
ution of 280 eV for the line of 5.9 keV. The energy of
protons was equal to 2 MeV. Fig. 2 represents standard
dependencies of gold L-line yield as a function of its
content of electrolyte and conditions of cathode depos-
ition.
Deposition is most complete for standard gold solu-
tion (curve 1), where the degree of deposition is 70%
for 1 µg dissolved in 25 ml, and 100% for 0.01 µg dis-
solved in 25 ml, and 100% for 0.01 µg dissolved in
25 ml. In cathode deposition of gold from thiourea in
optimum conditions, the degree of deposition made
21% for 1 µg dissolved in 25 ml and 60% for 0.02 µg
dissolved in 25 ml. In all cases, the time of cathode de-
position was 30 min. The gold minimum detectable con-
centration of such method was 2 ng/g.
Whenever the method of analysis involved decom-
position of the sample, sorbtion with subsequent direct
Van Graaff accelerator determination of noble metals in
sorbent applied on the carbon plate, the obtained detec-
tion limit reached 50 ng/g due to the presence of iron,
calcium, strontium, bromine, zinc impurities in it, and,
hence, their increased background radiation. Fig. 3
gives a typical spectrum of an ore sample containing
Au, Pt, Pd, Ag. This variant of analysis proves to be
most effective for the elemental analysis of ore with in-
dustrial content of noble metals.
USE OF MULTIPLY CHARGED IONS TO
DETERMINE GOLD CONTENT OF ORES
The use of multiply charged carbon and nitrogen
ions with an energy of 5 - 7 MeV to induce PIXE M-
lines in gold provided high content of medium weight
metals (А = 40 - 80) deserves special attention. In this
case, only gold provided high content of medium weight
metals (А = 40 - 80) deserves special attention.
0 100 200 300 400 500 600
channels
5
2
3
5
2
3
5
10
100
1000
co
un
ts
ju
vl
Ca
Ca 2
Fe
Fe 2 Zn
Pt
Au
Pt 2
Au 2
Br
Sr
Sr 2
Pd
Ag
Fig. 3. Spectrum PIXE of sorbent from a sample of auric ore
In this case, only M-lines in elements are excited, which
makes it possible to determine gold content at the level
of 0.1 ng/g. Ionization cross-section for equal velocities
of impinging particles is in proportion to Z2 (Z – is the
charge of incoming particles), the type of ions employed
has little effect on the intensity of braking radiation [5].
Therefore, signal/background ratio is higher when mul-
tiple charged ions are utilised. The gold M-lines with
the energy of 2.12 and 2.20 keV were registered with an
X-ray spectrometer. A 1 - 5 mg/cm2 thick zircon X-ray
filter protected by a 50 µm thick beryllium film against
backscattered particles was used to reduce target back-
ground radiation with energy of more than 2.215 keV.
Interference caused by phosphorus K-lines, zircon and
niobium L-lines was eliminated by applying electrolytic
deposition as these impurities do not deposit at the cath-
ode. Optimum gold electrolysis conditions were redu-
cing possible interference from platinum, iridium and
osmium.
600 650 700 750 800 850 900
channels
20
40
60
co
un
ts
ju
vl
La Ce
Nd
Sm
Fig. 4. Spectrum PIXE of a precipitate of ethanedioic acid
DETERMINATION OF RARE-EARTH ELE-
MENT CONTENTS OF ORES
The increasing demand for rare-earth elements used
in production of anticorrosive, heat-resistant, high-tem-
perature alloys calls for development of more sensitive
methods of determining their content in ores, mine and
dressing mill spoil heaps, etc. Determination of each
rare-earth element by methods employed in analytical
chemistry presents a challenging task. Chemical group
deposition of REE combined with PIXE method makes
it possible to effectively solve the problem.
The design of experiment includes sample decompos-
ition, multiple precipitation of rare-earth elements by
ammonia solution, dissolution of the precipitate in hy-
drochloric acid followed by rare-earth elements precipit-
ation by oxalic acid solution The process of analysis of
the manganese ores was modified by including after am-
monia precipitation the additional operation of electro-
lytic deposition on mercury-pool cathode. The resulting
precipitate was applied on carbon base and analysed
with Van Graaff accelerator using PIXE induced by pro-
tons with the energy of 2.3 MeV. As L-lines interfere,
K-radiation was used for selective detection of rare-
earth elements. When the energy of protons is
2 -3 MeV, the K-shell ionisation cross section is by 2 - 3
orders of magnitude smaller than that of L-shell in rare-
earth elements. The minimum detectable concentration
for ores was 0.1 µg/g. It quite satisfies the requirements
for exploration and processing of commercial ores [6].
Yttrium is determined at the level of 10−5 g/g without any
sample preparation. It further served as inner bench
mark for oxalic acid complexes. Fig. 4 shows typical
proton induced PIXE in oxalic acid precipitate.
Thus, the developed nuclear-physical methods of mi-
croanalysis of noble and rare-earth elements can be used
in exploration and development of industrial deposits of
noble and rare-earth ores, their determination in mine
and ore dressing mill spoil heaps, as well as in geology,
environment protection and medicine.
In conclusion we would like to thank Mr. V.V. Zo-
lochevsky for his kind assistance in completing this
work.
REFERENCES
1. L. Feldman, O. Mayer. Osnovy analiza poverhnosti i
tonkih plenok. M. Mir, 1989, 230 p. (in Rus.).
2. Yu.A. Zolotov, N.I. Kuzmin. Kontsentrirovanie mik-
roelementov. M., 1982, 288 p. (in Russian).
3. R. Bok. Metody Razlozhenija v analiticheskoj himii.
M., 1984, 482 p. (in Russian).
4. T.V. Shishkina et al. Zoloto v prirodnyh vodah, Pre-
print OIJaI, 122-99-325 (in Russian).
5. А. Johanson, T. Johanson. Analytical application of
particle induced X-ray emission // Nucl. Instr. Meth.
1976, v. 137, p. 473-534.
6. А.А. Valter, N.P. Dikiy, E.P. Medvedeva, Yu.V. Lya-
shko et al. Yaderno-fizicheskie metody opredeleniya
blagorodnyh i redkozemelnyh metallov. Sb. Mezhd.
Conf. “BRM-94”, Donetsk, 1994, Ch. II, c. 33-34.
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
DETERMINATION OF RARE-EARTH ELEMENT CONTENTS OF ORES
|
| id | nasplib_isofts_kiev_ua-123456789-78516 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T17:18:54Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Dikiy, N.P. Borovlev, V.I. Zabolotny, V.D. Lyashko, Yu.V. Medvedeva, Y.P. Slabospitsky, R.P. Fedorets, I.D. Shlyakhov, N.A. 2015-03-18T17:21:02Z 2015-03-18T17:21:02Z 2001 Nuclear-physical methods of analysis of noble metals and rare-earth elements / N.P. Dikiy, V.I. Borovlev, V.D. Zabolotny, Yu.V. Lyashko, Y.P. Medvedeva, R.P. Slabospitsky, I.D. Fedorets, N.A. Shlyakhov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 81-83. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS: 87.58.Ji.. https://nasplib.isofts.kiev.ua/handle/123456789/78516 A summary of the analysis noble and rare metals by combined methods is presented. The electrodeposition of gold at a carbon film and Rutherford backscattering was used for determination its in ores. The sorbents and particle induced X-ray emission was used for determination rare and noble metals in ores. The minimum detectable concentration for ores was 0.1 mg/g. In conclusion we would like to thank Mr. V.V. Zolochevsky for his kind assistance in completing this work. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Application of the nuclear methods Nuclear-physical methods of analysis of noble metals and rare-earth elements Ядерно-физические методы анализа благородных и редкоземельных элементов Article published earlier |
| spellingShingle | Nuclear-physical methods of analysis of noble metals and rare-earth elements Dikiy, N.P. Borovlev, V.I. Zabolotny, V.D. Lyashko, Yu.V. Medvedeva, Y.P. Slabospitsky, R.P. Fedorets, I.D. Shlyakhov, N.A. Application of the nuclear methods |
| title | Nuclear-physical methods of analysis of noble metals and rare-earth elements |
| title_alt | Ядерно-физические методы анализа благородных и редкоземельных элементов |
| title_full | Nuclear-physical methods of analysis of noble metals and rare-earth elements |
| title_fullStr | Nuclear-physical methods of analysis of noble metals and rare-earth elements |
| title_full_unstemmed | Nuclear-physical methods of analysis of noble metals and rare-earth elements |
| title_short | Nuclear-physical methods of analysis of noble metals and rare-earth elements |
| title_sort | nuclear-physical methods of analysis of noble metals and rare-earth elements |
| topic | Application of the nuclear methods |
| topic_facet | Application of the nuclear methods |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/78516 |
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