ilias, jaca, spain 5 of december 2006 se-82 purification: distillation and rectification procedures...
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ILIAS, Jaca , Spain 5 of December 2006
Se-82 purification: distillation and rectification procedures
Kornoukhov Vasily
INR RAS (Moscow)
for IChHPS (Nizhny Novgorod) and IRE (Moscow)
LAL, Orsay , Spain 1 – 2 of June 2006
SuperNEMO: radiopurity requirements
Tl-208 (232Th chain) <= 2 Bq/kg
(<= 1.5 ppt of Th-232)
Bi-214 (238U chain) <= 10 Bq/kg
(< = 10 ppt of U-238)
232Th 1,41·1010 y
228Ra 5,75 y
228Ac
6,15 hours
228Th 1,91 y
224Ra 3,64 d
220Rn 55,3 sec
216Po 0,158 sec
212Pb 10,64 h
212Bi 60,5 min
208Tl 3,10 min
36,2 %
T1/2 ~ 1010 y
T1/2 ~ years
T1/2 ~ days
T1/2 ~< hours
ILIAS, Jaca , Spain 5 of December 2006
SuperNEMO: dangerous isotopes from 232Th chain
Th-232, Ra-228, Th-228
We must remove Th and Ra
How to check the procedure:
Th: 232Th (MS), 228Th (HPGe: 208Tl line)
Ra: 228Ra (HPGe: 228Ac line)
238U 4,51·109 y
234Th 24 d
234mPa
1,18 min
234U 2,47·105 y
230Th 8,0 ·104 y
226Ra 1602 y
222Rn 3,824 d
218Po 3,05 min
214Pb 26,8 min
214Bi 19,7 min
T1/2 ~ 103 - 109 y
T1/2 ~ days
T1/2 ~ minutes
ILIAS, Jaca , Spain 5 of December 2006
SuperNEMO: dangerous isotopesfrom 238U chain
Ra-226
We must remove Ra
How to check the procedure:
Ra: 226Ra (Champagne method, HPGe: 214Bi line)
ILIAS, Jaca , Spain 5 of December 2006
SuperNEMO: dangerous isotopes and elements
• 238U chain:
Ra-226
• 232Th cain:
Th-232, Ra-228, Th-228
Conclusion: we must remove Ra and Th
ILIAS, Jaca , Spain 5 of December 2006
Industrial scale production of 82Se
At present
the only technology for industrial scale production of 82Se is centrifugation method
and
only site for ~ 100 kg-scale production is Svetlana (the ECP, Siberia)
ILIAS, Jaca , Spain 5 of December 2006
82Se transformation at Svetlana (the ECP)(V.Kornoukhov for ILIAS meeting, Orsay, April 2005)
Patent #… is “valid” in Russia onlynatSe natSeF6 centrifugation 82SeF6
82SeF6 (glow discharge) 82Se + …
82Se washing with H2O (to remove F-ions)
Distillation of 82Se in vacuum
“Chemical features” of impurities (chemical forms): fluorine compounds (!)
ILIAS, Jaca , Spain 5 of December 2006
General remarks concerning the problem:(+)
• Se is material for semi-conductive industry: there are many methods for its purification;
(-)• 82Se is a result of chemical transformation through
SeF6 compound, and behavior of U-, Th-, Ra-impurities presented in such product (fluorine compounds) could be quite different of impurities in selenium produced accordingly to standard technology.
ILIAS, Jaca , Spain 5 of December 2006
Chemical forms of U, Th, Ra impurities in isotopically enriched Se
There is no exact information on chemical forms of U, Th, Ra impurities at their low concentration in selenium.
There are no data on solubility of U, Th, Ra compounds with oxygen, selenium, fluorine in liquid Se.
No data on adsorption ability of U, Th, Ra impurities on heterogeneous particles of submicron size.
ILIAS, Jaca , Spain 5 of December 2006
Some properties of elementary seleniumMolecular composition of Se:
Vapor (at 700 – 1300 K): Se2 – Se8
Melt (at 494.3 – 958.4 K): mixture of cyclo-Se8, katenapoly-Sen
(n = 102 – 103), and polycyclo-Sen in chemical equilibrium.
Solid: Seα, Seβ – Se8, Sehex. - Sen
Melting Point, K. Se - 443; Se - 453; Sehex – 494,3
Boiling point, K – 958.4
Density, g/cm3: Seα – 4.46; Seβ - 4.50; Se hex. – 4.717; Seliq (550 K) – 3.918
Industrial sources of Se of technical grade (99.0 – 99.7 %):
Production of sulfuric acid and non-ferrous metals
ILIAS, Jaca , Spain 5 of December 2006
Distillation procedure & NEMO detector
Group from INR RAS (in 1997):
116Cd distillation for NEMO-3 detector
(two portions, 0.15 kg + 0.15 kg):
good result!
ILIAS, Jaca , Spain 5 of December 2006
Physical methods of Se purification
Distillation methods: 1. One – Stage (Simple) distillation
2. Multi-Stage distillation methods:
a. Repeated simple distillation of purified product from previous stages.
b. Rectification – multi-stage counter – current method, realized in one apparatus and in one process.
Purification of selenium by distillation method
Essence of method: impurity content in equilibrium vapor and liquid is different. х ≠ y
Elementary separation process:
Influence on the system with initially uniform impurity distribution leading to appearance of spatially divided parts of system with different impurity content. The physical action leading to separation in distillation methods:
- evaporation part of liquid
- condensation part of vapor.
Condition of separation:
у
α = ≠ 1
х
Conditions of effective separation at distillation:
у
α = >> 1 for highly volatile impurities
х
у
α = << 1 for non-volatile impurities
х
Separation coefficient at the equilibrium
“ liquid-vapour” for some impurities in Se at 684oC
Impurity Content, mas.%
S
Te
As
Sb
Hg
Metals
0,1-1,0
0,01-1,0
0,014-0,3
0,3-2,0
0,04-0,006
0,01-0,001
2,12
2,6
66,6
625
4,7
102-107*
* ideal separation coefficient
60 80 100 120 140 160
105
106
107
108
Se commercial
Se after special purification
ni, cm-3
d, nm
Distribution on size of heterogeneous particles in selenium.Determination method – laser ultramicroscopy
0,1 1 10 100
0
20
40
60
80
100
2
1
ef
Veval
*106, cm3cm-2s-1
Particles diameter, 1 - 130-140;2 - 80-90.
Effective separation coefficient ofheterogeneous particles in Se as function of evaporation rate
Multi-Stage methods
1. Repeated simple distillation of purified product from previous stages.
2. Rectification – multi-stage counter – current method, realized in one apparatus and in one process.
Impurity Content Impurity Content
Na 3.00E-08 Al <6.00E-04
Fe <4.00E-04 Mg <3.00E-04
Mn <1.00E-04 P <1.00E-04
Sn <7.00E-05 Ni <7.00E-05
Te <6.00E-05 Bi <4.00E-05
Pb <4.00E-05 As <2.00E-05
Rb <6.00E-06 Sb <2.00E-06
W <3.00E-07 Ta <2.00E-07
Ir <2.00E-07 Au <4.00E-08
K <1.00E-08 Zn <5.00E-09
Cr <4.00E-09 Ag <2.00E-09
Co <8.00E-10 Cs <2.00E-10
Cd <2.00E-10 Hf <1.00E-10
Cu <1.00E-10 Sc <6.00E-11
Ga <4.00E-11 La <1.00E-11
U <9.00E-12
Impurity content, (at %), in Se, purified by rectification
Determination method of impurity content – activation analysis
10-4 at% - 1 at. ppm
10-7 at% - 1 at. ppb
10-10 at% - 1 at. ppt
ILIAS, Jaca , Spain 5 of December 2006
Organizations/institutes could be involved in purification of 82Se
Russia (distillation method):Svetlana (the ECP, Siberia)Kurchatov Institute (Moscow)The IChHPS (Nizhny Novgorod)The Institute of Rare Earths (Moscow)Mendeleev Institute (Moscow)
USA (“wet” chemistry):
INEEL (Idaho Falls)
Coordinator (ILIAS/SuperNEMO): Dominique Lalanne
ILIAS, Jaca , Spain 5 of December 2006
The IChHPS & the IRE: goal and content of workGoal: Foundation and selection of technique for production of
high-purity 82Se according to the requirements of SuperNEMO project; its technological realization for production of ~100 kg.
Parameters of the productElementary selenium enriched with 82Se isotope with the
content of impurities of Th, Ra (U) 10-10 at.% ( 1 ppt).Requirements to technology
- The yield of the product is 90-95% (to be specified during investigations)
- Output of technological scheme and equipment is 5-10 kg/cycle
- The process instrumentation should preclude the unrecovered losses of 82Se even in force majeur (destruction of equipment)
- To exclude the isotopic dilution during purification procedures
ILIAS, Jaca , Spain 5 of December 2006
The IChHPS& the IRE: content of work
1. Thermodynamic and experimental evaluation of chemical and aggregate forms of the limiting impurities and of their relative volatility in selenium produced from SeF6.
2. Experimental verification of purity of Se with natural isotopic composition with respect to the limiting impurities purified by multi-stage vacuum distillation and rectification. Verification of abilities of these methods during production of kilograms amounts of Se extracted from SeF6.
3. Selection of technological process scheme with optimization by numerical methods of the degree of purity, output capacity and reliability.
4. Fabrication of equipment for the process with output capacity of 5-10 kg/cycle.
5. Production of pilot lots, characterization of the product, modifications of the selected scheme and technological modes.
ILIAS, Jaca , Spain 5 of December 2006
Basic stages at development of ultrapurification process
1. Characterization of initial substance (determination of content and nature of impurities).
2. Development of analytical method(s) to control limited impurities with necessary detection limit.
3. Choice of purification method; a priori calculation of apparatus and mode of operation. Fabrication of apparatus.
4. Preliminary experiments on purification.
5. Correction of apparatus construction and mode their operation.
6. Final experiments on ultrapurification. Characterization of high-purity products.
ILIAS, Jaca , Spain 5 of December 2006
Conclusion• At present the only technology for 82Se production is
centrifugation method and only site for 100 kg- scale production is Svetlana (the ECP, Siberia)
• “Chemical features” of impurities in such a product (chemical forms): fluorine compounds.
• Multi-stages distillation and rectification methods of purification: the IChHPS and the IRE are ready to start purification of Se in the framework of ILIAS.
• Quality control with “champagne” method could be easy organize at very last stage of the purification procedure
C, мкг/гЭлемент Метод ПО, мкг/г Se-82
Li MS, AES 0,001 < ПОBe MS 0,001 < ПОB MS 0,04 < ПО
Na AES 0,7 < ПОMg AES 0,02 < ПОAl MS, AES 0,1 < ПОK AES 2 < ПОCa AES 0,5 < ПОSc MS 0,1 < ПОTi MS, AES 0,2 < ПОV MS, AES 0,1 < ПОCr MS 0,1 < ПО
Mn MS, AES 0,02 < ПОFe AES 0,6 28,2Co MS, AES 0,05 < ПОNi MS, AES 0,3 < ПОCu MS, AES 0,07 < ПОZn MS, AES 0,1 0,30Ga MS 0,01 < ПОSe AES ОсноваRb MS 0,001 < ПОSr MS, AES 0,003 < ПОY MS 0,001 < ПОZr MS 0,002 < ПОNb MS 0,02 < ПОMo MS 0,05 < ПОRh MS 0,0001 < ПОPd MS 0,0005 < ПОAg MS 0,01 0,030Cd MS 0,003 < ПОSn MS 0,05 < ПОSb MS 0,008 < ПОTe MS 0,02 161Cs MS 0,003 < ПОBa MS, AES 0,005 < ПО
La MS 0,001 < ПОCe MS 0,001 < ПОPr MS 0,0008 < ПОNd MS 0,0005 < ПОSm MS 0,001 < ПОEu MS 0,0001 < ПОGd MS 0,00008 < ПОTb MS 0,00001 < ПОDy MS 0,0002 < ПОHo MS 0,0001 < ПОEr MS 0,00002 < ПОTm MS 0,00006 < ПОYb MS 0,00005 < ПОLu MS 0,00007 < ПОHf MS 0,00009 < ПОTa MS 0,003 0,056W MS 0,5 11,1Re MS 0,001 < ПОIr MS 0,00002 < ПОPt MS 0,0001 < ПОAu MS 0,001 < ПОHg MS 0,009 < ПОTl MS 0,00007 < ПОPb MS 0,02 < ПОBi MS 0,0004 < ПОTh MS 0,00006 < ПОU MS 0,00003 < ПО