1967-09-30 – Mallinckrodt – Fuel for the Atomic Age – Report on St Louis-Area Uranium Processing Operations

1967-09-30 - Mallinckrodt - Fuel for the Atomic Age - Report on St Louis-Area Uranium Processing Operations

Leave a Reply

Your email address will not be published. Required fields are marked *

~ V~Lit~S\f\~J)
w~~~
. .
•mpletion Report On St. Louis· Arta Uranium Processing Operations, 1942 -1967
~ I
LEGAL NOTICE
This report was prepared as an account of Government
sponsored work. Neither the United States, nor the Commission,
nor any person acting on behalf of the Commission:
A. Makes any warranty or representation, expressed or
implied, with respect to the accuracy, completeness, or usefulness
of the information contained in this report, or that the use of any
information, apparatus, method, or process disclosed in this .report
may not infringe privately owned rights; or
B. Assumes any liabil ities \IIi th respect to the use of,
or for damages resulting from the use of any information, apparatus,
method, or process disclosed in this report.
As used in the above, 11person acting on behalf of the
Commission” includes any employee or contractor of the Commission,
or employee of such contractor, to the extent that such employee
or contractor of the Commission, or employee of such contractor
prepares, diss eminates, or provides access to, any information
pursuant to his employment or contract with the Commission, or his
employment with such contractor.
-II· * * *
This report was prepared by Fleishman-Hillard, Inc.,
St. Louis, Mo . , under Mallinckrodt Chemical Works -Uranium Division
Subcontract 25188-M of July 11, 1966, as modified. The report
was prepared in connection with Mallinckrodt Chemical Works’
performance under Contract No. W-14-108-Eng-8 (Principal Contract),
as modified, with the United States of America acting through the
United States Atomic Energy Commission.
,,,
FUEL FOR THE ATOMIC AGE
Completion Report On St. Louis-Area
Uranium Processing Operations, 1942 – 1967
September 30, 1967
I.e !
TABLE OF CONTENTS
Page
Section I, Fuel for the Atomic Age (General Summar~ . …. 1
Section II, Technological Developments
Part 1, Commercial Reduction and Casting of
Uranium Metal. • • • • • . • • • • • • • • • • • • • • • • • • • • • . • 8
Part 2, Development of the First Commercial
Process for Ether Extraction of
Uranyl Nitrate . . . . . . . . . . • . . . • • • . . • • . . . . . . . . 18
Part 3, Development of the Continuous
Ether-Extraction Process .•••..••••…. •• .• • 25
Part 4, Development of the Tributyl Phosphate-
Hexane Process for Uranium Purification . … 32
Part 5, Development of the Pot Process for
Converting Uranyl Nitrate to Orange
Oxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . • 42
Part 6, Development of the Fluid-Bed
Denitration System .•• ..•• ••• •.•.•• . • •.• •••• 49
Part 7, Development of the First Factory
Process for Producing Brown Oxide …. .• … . 59
Part 8, First Factory Production of Green
Salt in St. Louts . ••…••. •• • … •. .. • ••.•• • 65
Part 9, Development of the Continuous-Process
Stirred-Bed Reactor for the Production
of Green Salt and Brown Oxide .. •• .• ••• ….• 72
PartJD, Advances in Continuous-Process
Production of UF4 – Development of
the Integrated Fluid-Bed System •••••.•••..• 81
Part ll, Development of the Dingot Process
for Producing Uranium Metal .••• .••• .• •• . .• • 96
I
Sect ion II (continued )
Part 12, Development of t he Electrolytic
Reduction Process .••..•.. • • • • • .• • • •..• … 109
Part 13, Miscellaneous Technical Developments •• ••• 114
Section III, Organization & Management
Part 1, Organization and Management •.••• • • ••.•••• • 118
Part 2, Material Accountability ..••..•• • • . • • • • • • . • 132
Part 3, Plant Security •••••••.••. • ••• . . . •.. • •.. • •• 136
Part 4, Heal th and Safety.. . . • . . . . . . . . . . . . . . . . . . . . 144
! · Section N , Producti on and Cost …… .. . . .. … … .. …. 157
!
Section V, Conclusions •..•••. • ••..•. • .. •••.•••..•.. •. . • 164
Bibliography . . . .. .. . . · …. . . . . . . . . .. . … . … .. . . , . . . . • . . 167
I .e
.._._.,. .,.,,:J:;f”‘l•t..•: ‘t ~ . …… , .,.,.,. •-:;.·.·*’:. –< ~• ••• ~r. .. •"..t 1(.,1.,-:~ " •. -c.')\!·*~ •k·W..f.: .Z..··\1'¥·••,•· ..; "- .....:( .•• ., • ., .. ,, .. , ••" ', ,;.,·.;. ~.-:<~~'11~.. . .• · •••••• ·t· ••. • ·. .... ' ·~·· ·.<:> . .; · · ·. : .· . .:.–···,;.:·· .,, -;.·t·.:·:··· ~,· … .-~ .;·\ :,•\,· ‘:·’.·.,:-<.:;·.f(.-:;,r,~ .• ~· ~.:r '"'":·.·~:. · ·'·· .·, . ··: · .-... , -.~• -·-: • . · . . . \,. ~ • ' o .·, ; o• o : ~ 0 " •o 0 +,(' ', 0 .,S 00• 0 • "" 0 ,.,,,.'' ;, 0 f'o 0 °' 0~ o .a ,, :.-. ~ :: o\o".· :.\ . '":. ........ •< ~ ;\· .~t; I ... O ,t.,:';.·. J!l.!ll l,,o O 0 ~ : )ltl' 00 0 : ~ o \ ',:~:·• o :.:: 0 O 0 0 ... ~· oo 0 , 0 i.. ~ - . ~\·•: :·:,.·•. .· ·,\; ~':""I'"\' ...., .,, ' ··:"d'~mJt. ";._;.t,, ... i c.~-t"-' t,;)~~,…,,. .,,.., … .c… . ,.,:,oJ·,…, ,• •.••~ ~~”·,..,, ·#”o~r.··):tt •,· ·::~:,… ;• &”··. …. •• • •• , …. ‘l • .; .:,
i~:~:::~~;};L;;}~;c~;,i:~·::L:&tX~::::.YK~:~’!J:f:¥i!;if/}1~~~:.%\tt::/NDk~~&.:~:;.;/t.~~>t ::·::.;:.~::·~-;~·. -.’ ….· . :: ·:. ,· .. .· I ~\l-. :J •• …. ~.,.1,.., .. .,,,_. ….. , ·><~""· ......... ~.-.• ·J·~·>‘·••·~ •~t,.J~ .. -~•’-‘·}~”.i!’;,wQ~) ~~·~··,,,. … f>.; …. ,.., ….. ,., •• _,.,.v, .• , …. :l.;, • .• ~ . ……. ~ ,.,., ,,, . •. , .. :· . .. •.• ..
‘ ……
I J. ..
.. ·· . ‘ …· : ·: ….· . ··’· ~ . ‘ . ·. . . .. .. . ,, .. : ‘ \ . ::·. · .. ~· …
• ‘i· •• . .. . • .. . … ,, ·. … … ..; ,..· .
,·,· .. •,: ·. . · ·. … .. .’· . ..
• ‘.’ ‘ ‘ • • ‘I ~ ……. · .. ‘•;
• oo1,; . . .. , ..
··: \ ,,·
… … . . ··.· ‘ . ::·~ . ,
·’
Sect1o·n I .· ….
. ,: ~ “‘I •’ ‘ … ·.’
. ….. t

… . -: .. ·: : .. ‘ 1
·. ·.· . …
. ·.: . .. . : …… . … .. .
. : •… : ……. ~-.
….. -… -. … …. -……. . . ,_ ., . .,..J ·~~ Li·. }: ·;: :. :·
;.. . …. ··:·. .: ·::··. .: ·. .. •’ ••••• • ••• \ :0•
·.
– 1-
Section I
FUEL FOR THE ATOMIC AGE
An Introduction to the History
of Mallinckrodt Chemical Works • Uranium Production
and Development Activi ties
for the United States Government
11The story of the supply of uranium
is by itself a thrilling one, and
the production of enough pure metallic
uranium to do our task in time was a
technological and industri al miracle. 11
—- Arthur Holly Compton*
j * Arthur Holly Compton, Atomic Quest (New York : Oxford University
1 Press, 1956), p. 90.
-2-
On December 2, 1942, in the early days of vlorld War II,
the atomic age was born: the first self-sustaining, nuclear
chain reaction was achieved in what had been a squash court under
the West Stands of Stagg Field at the University of Chicago . On
that day, ” … man first liberated and controlled the power
within the atom. This event was known only to a few . To those
few it was a turning point in history, the birth of a new era.”*
The historic and dramatic accomplishment on that cold,
winter Wednesday in Chicago was the successful result of the
combined work, talents, and skill s of scientists, engineers,
technicians, and others working on related, super- secret projects
in various parts of the nation.
One of the most important parts of the hush- hush
scientific – industrial complex was the uranium project at the
Mallinckrodt Chemical Works plant in St . Louis, Missouri . Its ·
work was a vital link in the chain of activities which led to the
birth, and subsequent development and advancement of the atomic
age .
This document is a history of the Government’s uranium
operations in the St. Louis area. Officially, it i s €1. “completion
report” describing Mallinckrodt 1 s operat.ions from July l~ 1942,
through June 30, 1967, under Contract No~ W-14-108-ENG.-~ for
the United States of America. To provide perspective, the report
discusses significant event s and activities from Martin Heinrich
Klaproth1s discovery of uranium in 1789 to Ma llinckrodt’s initial
involvement in uranium-processing research in the spring of 1942.
It continues through the termination of the Company’s standby
contract with the AEC in June, 1967 .
Figure I is a chart summarizing the major contributions
of the Mallinckrodt organization to the Government ‘ s uranium
processing and development efforts in the St. Louis area during
the 25-year peri od from July, 1942, through June, 1967.
*Ibid . , p. 139 ·
-3-
TWENTY-FIVE YEARS OF URANIUM PROCESSING AND DEVELOPMENT
MAJOR CONTRIBUTIONS BY MALLINCKRODT CHEMICAL WORKS
* First Commercial Process for Ether Extraction of
Uranyl Nitrate
* First Factory Production of Orange Oxide from Uranyl
Nitrate
* First Factory Process for Producing Brown Oxide
* Early Production of Green Salt
* Early Commercial Reduction and Casting of Uranium
Metal
* First Stirred-Bed Reactor for Continuous-Process
Production of Green Salt and Brown Oxide
* First Commercial Continuous Ether-Extraction
Process
*
-1<· * * * First TBP-Kerosene and TBP-Hexane Processes for Uranium-Ore Refining Numerous· Advances in Uranium Metal Production, Including Slag Liner, Dingot-Extrusion, and Electrolytic Reduction First Successful, Commercial Fluid-Bed Denitration System First Integrated, Continuous-Process Fluid-Bed Uranium Production Adaption of Uranium Processing Equipment to Commercial Production of Purified Dense Theria Continuous Cost Reduction Through Advances in Manufacturing Practices and Scrap Recovery Consistent Fulfillment of AEC Production Objectives Figure I -4- . ~ Objectives Of The Report . e I The objectives which guided the preparation of this report were: (l) (2) (3) (4) (5) To provide a single document describing the major aspects of the technical and administrative history of the Government's uranium processing operations in the St. Louis area. To explain the rationale underlying the technical and administrative developments of the operations. To produce an evaluative instrument for comparing and appraising present and future operations of a similar nature. To provide a general guide for the establishment of similar operations in the future . To organize a one- source reference on the highlights of the first major processing contract to be phased out in line with the Government's evolving requirements. (6) To contribute to the literature in the fields of uranium-production technology, nuclear science, chemistry, and technical and administrative management. The report is \'lri tten in a semi- technical tone to make it meaningful and useful not only to persons with technical backgrounds, but also to those whose orientations are not primarily technical. Summary And Organization Of The Report This report consists of five major sections . This section, Section I, is an introduction and general summary of the entire document. Section II, which comprises the bulk of the report, is a history of the philosophy·behind the major technological developments of the St. Louis-area uranium operations. The emphasis of the material in Section II is on the rationale underlying the developments rather than on detailed descriptions of the developments themselves . The _ detailed descriptions can be found in a variety of other technical reports and documents . I I . -5- Because the uranium effort in the St. Louis area was primarily technical in nature, the history of the operation is, in large part, a technical history. It began in April, 1942, when Dr. Arthur Holly Compton, Dr. Norman Hilberry, and Dr . Frank H. Spedding approached Edward Mall+nckro d~, Jr., to seek his Qompany's assistance in preparing the extremely pure uranium compounds wnich were needed as fuel for an experimental atomic reactor at the University of Chicago. The reactor, if successful, would achieve a self-sustaining nuclear chain reaction. The whole project was of extreme importance to the national security. At the time, the United States had been engaged in World War II for nearly a year, and the nuclear reactor experiment had the potential for making a major contribution to the war effort. A successful nuclear fission reaction, on a proper scale, would release an incredibly enormous amount of energy, and could produce an explosion of immense proportions . The possibility that scientists of the Axis powers might develop a device to achieve such a frightening explosion made imperative a vast effort -- the Manhattan Project -- within the United States to develop such a device first . It was in this tense, wartime environment that Mallinckrodt was asked to produce the key uranium compounds which were needed before fur t her progress could be made. Dr . Compton and his associates at the University of Chicago already had approached several other major chemical producers to ask their assistance, but they all declined -- partly because of other wartime commitments, and partly because of the difficulty and risk involved in the uraniumpurification assignment. To produce the needed uranium fuel, impure uranium concentrates would have to be purified by extraction with ether . Never before had the extraction been achieved on anything but a laboratory scale, and even on that small scale, the explosive and erratic nature of the ether made the operation extremely hazardous, Dr. Compton turned to Mallinckrodt because he was familiar with the Company's outstanding reputation for safely producing highquality, high-purity products, and because he knew that the Company was expert in handling ether. Mallinckrodt accepted the challenging assignment, and within 50 days, the Company accomplished the "remarkabl e achievement" of producing highly purified uranium oxide on a tonnage scale. -6- At that time, the Company's uranium products included, uranium trioxide (U03, or orange oxide), and uranium dioxide (U02 , or brown oxide ) . Later in 1942, Mallinckrodt started production of uranium tetrafluoride (UF4, or green salt). When the first self-sustaining nuclear chain reaction was achieved on December 2, all of the uranium in the pile was in the form of uranium dioxide produced by Mal linckrodt or uranium metal prepared by others from intermediate materials produced by Mallinckrodt . A few months later, in July, 1943, Mallinckrodt started its first metal plant. During the 25 years that it was involved in uranium production, Mallinckrodt made numerous contributions to uraniumprocessing technology . This report discusses most of the Company ' s major contributions including the development of the first commercial process for ether extraction of uranyl nitrate; the first continuous ether-extraction process; the tributyl phosphate-hexane process for uranium purification; the pot process for converting uranyl nitrate to orange oxide; the fluid-bed denitration system for producing U03; the first factory process for producing brown oxide; improved methods for batch- type, factory production of green salt; the continuous-process, stirred-bed reactor for producing green sal t and brown oxide; advances in conti nuous- process production of green salt by means of the Mallinckrodt integrated fluid-bed system; improved methods for casting and reducing uranium metal; and the dingot and electrolytic reduction processes for producing uranium metal . Section III is a history of the administrative development of the St. Louis-area uranium operations beginning with the initial efforts in 1942 in Mallinckrodt 's building 25-2 research laboratory and continuing through the final act ivities at the AEC 's Weldon Spring facility in 1966. The subjects discussed in Section III include organization and management, Mallinckrodt ' s experience and qualifications, contractual arrangements, physical f acilities and plant services, material accountability, plant security, and health and safety . Section IV deals with production and costs. In addition to discussing cost accounting, the section provides an interpretive narrative concerning Mallinckrodt- AEC negotiations, and other pertinent subjects related to production and costs. Section V is a brief statement summarizing the conclusions of authorities concerning the significance of the work accomplished since 1942 by the Government's St. Louis-area uranium operations . .e .e -7- For almost a quarter of a century, Mallinckrodt successfully carried out its uranium-processing contracts with the Government, The Company, always surpassing its commitments under the requirements of the contracts, continually worked to lower costs, increase production and improve quality. In April, 1966, when the AEC announced its plans to terminate its St. Louis-area uranium production activities, Dr. Glenn T. Seaberg, Chairman of the Commission, praised Mallinckrodt for its excellent performance in the Government's atomic energy program. He called attention to the Company 's outstanding record of accomplishment for production operations and related process improvement and development programs. Dr. Seaberg said that Mallinckrodt 11can be justly proud of the important role it has played in the advancement of Re aceful uses of atomic energy and in our nation ' s defense efforts . 1 # '•. •,, o 0 fo •, • ,:.,• ,''••• .. : ..... • ' • ~ t .. • .... • . ... • ..... • ~ . .. .: ," , .·. ':', :. . ' , ¥ ••• • ' •• ·1 • •• ' • ~ :· ....: ',. ..; :~·:·:_(~:;. .: <;;.: ..: >~’- />_::::_ .> ..> . .: .. ,; . ·.· ‘·. ..
.. , .. ..
~-
…… Section II .. . ..
f:·j;::t~·: :· ·:·:· · … :::, ·>\_·. =···-·· .. .-‘Tec.ruiological Develo~~ents
·~·., … ,, ..· .. . • ,, ,~ • ,I , • , .,. ..,._ :: •, ,• • .-•• , ,, ;…, , • I ‘ :’• , , ,•,,.,.. • , • • ,
~- ;, .. \•.: •.. t: ·. • … : …. :. . ….. . .. ~ •. . -:, •…. · .. . .: . _,.,: •• ;~_ .•. · .-. • ·… • – •. 0 •••• •””. ,· • • -~: .. :_ • • . _·, ,.. .. . ‘ . . ……… . .v •. ~ …, …..
‘~.r!~.~-:;:~;:~~;_~~~–::·_ ::~ _-_;_~~~::_~_,:_~_::·_:~:~>~;-~-~-~-·::~-·_ ·_· : …. \~. …f .~._-_<_- -·._---)_::::-.......: _-;.:·:;·...: j:~-·-=: <<.· -~~::<:-:~ ...·. ·:. . ,.- -............. ~~::·.,:·:.:.~ ........ ·' .· ... ~~ · ... --~ - :-_.:,- ··.::\ rr:. .. .... .: : ·:. ,. ...: . . .·. -:·. :.' ,' :r ·:: '·?· '· .... . ... , • ·• .. :. ·-::-:-·.· .. ,'j: . . .... ' :: . :.:.·_ ·: . .:::: ·:· ~-·· ··: ... : : :-· . .. .·· . ... . ...·..· . . . .. · .· .' .. .... .. .. . .. , .-:,_: · • . . ; • ..;': ~,: •. :· .... - •. •• -.• • a.i ; . ; •. ;-::. :.; .: .. : : ·: .:.:. • .. •.• ,-. • ., tl •• •••• : • • : • • '··\ • • • •• •• · :. ~;. - ...: _ :: :. -::-::--·;::_ <·;' ::· (:~?:~·i.-;':. ':_,.·; .· .-: ·:·-.· ;,:·~-' ·... -->~-·. ._· .:·_. .1
:_-:/ :: ·:.:~t::=·~·;·:·~:~::,~~~-} } ·,,/:?-::·:::·-<~:-:~:·.·::. :'.~.: . . ... - ....... . ·' ...... .. ·. ...... :. .. ..: .. .. .., . ... _:.!.·~;.~~-... :__ . .. ·;.£. .. • ' .... : •••• :. · .. • • .: • • ' .. ::·' "' .... •• • • 0 ': . ; • 0 0- • .... ·:· ;·:,:··.·:; -::-:•· . ..-.-<~. • :. .. . +·: :. : ....... -, ... ~:.·_:.·:·:, .\.;·.:;I-'~_:;-.. :~~~>: .::·–~·. .: :>_-;·” .. .
..· …
··-
… ~ ~.-:·, .. !: … ~:·~;:. · .. .:::·:~· … . …. ,.
·.···.
~~~*~~~~~~~~~~~~~~~~~~~~~~~~~~~~J~~~~~~~~*;~2~·;·~~~ ~~t~~~~~:~J~ … ‘7i … , … 0 •••• • ••• ,. -·.
• 0 0 0 0 ,o, :.o: . t· .. .·. .. · ·.. . . .. . , ….
~~~~mif:r~i~·~~m:i~~~t-J.!~~;~·.:. :-:,:0··=-.· ::{·.- :;_;·:_·:.:;~~:i:/:::_~;;.-:~ ;-~,- ~: -….
. · .~:~ ·!·.:~.’-· -~-:~:·:.~.~-.. ~·/. ‘:·: -~ ;’ “.\
..,.,.-,;J~.~::·,:.y::, 93, 172, 186, 190, 192, 198, 199, 201, 211, 222 ,
223, 224, 225 .
Additional references may be found in some of the sources
indicated above.
#
– 25-
Section II
Part 3
DEVELOPMENT OF THE CONTINUOUS ETHER-EXTRACTION PROCESS
· In 1945-46, Mallinckrodt Chemical vlorks developed a
continuous ether-extraction process for purifying uranium, and
designed and constructed a large, tonnage-scale plant using the
process. With continuing improvements, the proces~ remained the
standard one at Mallinckrodt’s St . Louis operation until 1957
when tributyl-phosphate-hexane was introduced to replace ether.
Background
The original batch ether- extraction process, developed
on a crash basis, had several disadvantages. (The batch method
is discussed in detail in Section II, Part 2 . ) Chief among the
disadvantages were high operating costs and low percentages of
uranium recoveries . Further, removal of certain contaminants
from the uranium was insufficient, and the method required
relatively pure concentrates, which made extensive prior processing
of the starting materials necessary .
The New York Operations Office of the Manhattan District
initiated activity to explore the possibility of overcoming these
disadvantages. The office assigned to Yale University the task
of investigating the possiblities of a continuous ether- extraction
technique that would use feed solutions prepared directly from
pitchblende by nitric acid digestion .
The Yale work indicated that the approach might be
feasible, if a number of complicated inherent problems could be
solved.
Initial Development Work At Mallinckrodt
In the spring of 1945, as the Yale studies were being
completed, Mallinckrodt began research to develop a final, continuous,
counter- current ether-extraction process. Work was aimed at finding
a method-which would use feed solutions prepared directly from
pitchblende ores, or crude concentrates containing 30-80 per cent
black oxide.
I i .
– 26-
Mallinckrodt had to solve several complex problems,
some of which were revealed in the work at Yale. The major hurdles
were to:
– develop satisfactory methods to prepare
suitable feed solutions . ·
– cut down on impurity (especially molybdenum)
carry- through during extraction.
– ge.t more complete recovery of uranium.
‘rhe total job was two-fold: ( 1) development of workable
methods for preparing suitable feed solutions; and (2) research,
development, and design of the continuous extraction process and
equipment.
Preparation Of Suitable Feed Solutions
Mallinckrodt worked on developing two methods for
preparing feed solutions — one with pitchblende (containing
radium) as t he starting material, and one using radium-free
concentrates.
The method that Mallinckrodt developed for processing
pitchblende involved several steps . First, the original material
was ground, and then it was digested with nitric acid . The
resulting solution, however, contained -radium and sulfate , both
of which presented additional problems .
The radium posed a problem both because of its inherent
radioactivity hazards, and because of its high value . The sulfate
if not removed from the solution — would cause precipitation and
mechanical difficulties during extraction .
Mallinckrodt found techniques to overcome these problems .
The excess sulfate in the digestion batch was removed by precipitating
the sulfate with barium carbonate which also coprecipitated
the r.adium as sulfate . The precipitates were removed
by centrifuge techniques, leaving a feed solution with little
barium or sulfate.
Mallinckrodt’s preparation of feed solution using chemical
concentrates free of radium or sulfides and containing only
relatively small amounts of sulfate or calcium, involved simply the
digestion of the concentrates with nitric acid. The resulting
slurry, after adju~tment of free nitric acid and uranium content,
was used directly as the extraction feed .
-27-
One obstacle remained in the preparation of the extraction
feed . It was incomplete uranium dissolution. To dissolve the
uranium completely required an excess of nitric acid. During the
extraction process, the ether stripped the aqueous feed of acid
and this caused precipitation to occur . The prec ipitation, in turn,
caused sludging and emulsion which interfered with proper operation
of the extraction equipment. Mallinckrodt 1s solution to the
problem was to add a controlled concentration of nitric acid to the
ether to prevent the stripping.
Pilot Plant Development Of The Continuous Ether-Extraction Process
In addition to solving the problems associated with
developing feed-preparation processes, Mallinckrodt also had to
solve major problems in developing the extraction process itself.
In the spring of 1945, a pilot plant was built as an
annex to the batch ether-extraction plant then in use. The pilot
plant was used to carry out the extensive experimental work leading
to development of a practical, continuous, counter-current , dualcycle
ether-extraction process — one that could be translated into
a plant system.
In terms of the physical chemistry invo l ved, the continuous
process that Mallinckrodt developed was basically identical
to the batch process. An aqueous uranyl-nitrate feed solution is
dissolved in diethyl ether . Then the ether and water layers that
form are separated, and the purified uranyl nitrate is recovered
by further treatment of the e t her solution.
The continuous process developed by Mallinckrodt had two
cycles: (1) acid extraction, and (2) neutral extraction . The
process is illustrated in Figure II-3.1
Acid Extraction
The first stage of.the acid cycl e was the extraction
column, a tube packed with small cylindrical sections of ceramic
pipe to promote intimate mixing of the aqueous feed and the ether
phases. The ether was the continuous phase and was introduced into
the column at the bottom. It flowed counter-current to the aqueous
feed which moved by gravity from the top of the column . After
·passing through the extracting column, the uranium-enriched ether
phase overflowed from the top and was carried by pipe to the
bottom of a wash column.
The ether solution carried with it traces of impurities,
some of which were dissolved, and some of which were mechanically
entrained. (Part of the molybdenum, because it is soluble in ether,
was one of the impurities that was carried through.)
hffi noto
Solvbft ~lrott•
N.O. IIqvor
to Acid htJo<~on F.H Acfl"tlloont -28- WothWotor RoH'nott Coke Rhlolt to Acld$owor Produd Figure II-3 .1 THE FIRST COMMERCIAL CONTINUOUS ETHER-EXTRACTION SYSTEM was developed by Mallinckrodt as a dual-cycle process. -29- After it left the extraction column, the uranium-rich solvent stream was then passed through the wash column where small amounts of water were used to remove some of the impurities in the solution. · Re-extraction was the final step in the acid-extraction cycle. Large amounts of water were introduced into the top of the re-extraction column. The aqueous phase, f lowing by gravity from the top of the column, mixed with the uranium-rich solvent \'thich flowed counter- current to the water from the bottom of