JUSTIN T. LONG O a k Ridge National Laboratory, O a k Ridge, Tenn.
Engineering Developments in Fluoride Volatility Techniques were developed for contact of gases with molten salts, and design methods were devised for distillation of volatile inorganic compounds
IN
THE fluoride volatility process, a solution of uranium tetrafluoride is prepared in a fused salt mixture such as sodium fluoride-zirconium tetrafluoride eutectic. Uranium is separated by conversion to the hexafluoride. Trace impurities may be removed by adsorption or distillation (2, 76). Information is available on the use of uranium hekafluoride as a process gas and its adsorption and condensation have been studied thoroughly (24). Therefore, only the handling of fused fluoride salts is reported here, with the reaction of fluorinating agents with fused salt melts and the distillation of inorganic substances (73).
Molten Salt Handling
.L
Resistance Heating. Process lines mav be heated in several ways: external strip heaters, flue gases, or resistance of the pipe itself as electric current flows through it. However, strip heaters often burn out and do not heat evenly, and hot gases cool rapidly and require a n annular pipe which makes equipment changes difficult and expensive. Resistance heating with Inconel tubing is satisfactory in every regard. T o increase resistivity and therefore decrease the current required for resistance heating, a thin metal cross section is indicated? but because of corrosion a thick wall is desirable. Therefore, l/4inch tubing with a 35-mil wall was used during development and '//Z-inch Schedule 40 pipe for the pilot plant.. T h e pipe required larger currents but provided the additional safety factor needed in plant operation. T o achieve the desired temperature for molten salt use, a pipe with high electrical resistivity is needed. Inconel. with a resistivity of 590 ohmscircular mil/foot, was the most corrosionresistant material readily available. Only 0.01% of the current flows through the salt; the bulk flows through the metal wall. A current of 250 amperes is sufficient for bare tubing or insulated Schedule 40 pipe, but as high as 500 or 600 amperes with uninsulated pipe. Approximately 0.5 volt per foot is required-for a 20-foot length of tubing, 10 volts is sufficient.
Ohms-Circular
Mil/Ft. Poor Conductors
Ni-Resist Hastelloy B Hastelloy C Hastelloy A Inconel Invar Good Conductors Nickel Aluminum Copper
1050 812 800 762 590 480
44 17 10.4
\'essels were grounded and the voltage supply was attached to the midpoint of salt transfer lines to minimize stray currents. Service lines were carefully insulated electrically. Although the approximate point of electrical balance can be calculated, it was necessary to determine the exact neutral point experimen tally. Temperature gradients in the process lines of several hundred degrees Fahrenheit per inch may result from small uninsulated or poorly insulated areas. Operation near the freezing point of the molten salt is difficult under such conditions. Although the amount of insulation needed for adequate temperature control may be calculated, the actual insulation may have a gap of as little as '/4 inch, which might be disastrous. Gaps between layers of insulation should be staggered so that bare pipes do not lose heat to the atmosphere and cause plugging. An additional danger is the overheating of lines which are resistance-heated and enter a heated furnace I t was found experimentally that bare resistance-heated line was not greatly increased in temperature inside the furnace, In making electrical contact with the pipe a T-like connection is required, but the T becomes a fin through which heat escapes, causing a cold spot on the pipe. Testing various configurations of electrical stub with various amounts of insulation showed that a satisfactory combination was obtained when the base of the stub was of '/p-inch Schedule 40 Inconel pipe and the outer part was 1-
inch nickel rod, which has better oxidation resistance than copper and is still a good electrical conductor. It was possible to make a stub only 12 inches long, half Inconel (thermally insulated) and half nickel (bare), which maintained the base of the stub a t 1000° F. or above and the tip below 212OF. A differential equation may be set up describing the heat flow, from which the temperature may be determined a t any point along any stub coming out from a pipe maintained at a given temperature. However, because the equation represents idealized geometry and fabrication techniques never achieved in practice, experimental solution of the problem was preferable. Freeze Valves. A valve devised to seal molten salt lines against a gas prrssure of 20 p.s.i. without leakage was a vented loop where salt was trapped arid allowed to freeze. Earlier unvented loops always siphoned empty rather than sealing. When a salt shrinks upon solidifying, a reservoir of molten salt must he provided to flow into the cavities; otherwise, the frozen material will develop holes and will not hold against gas pressure. The loop, originally 12 by 16 inches, was reduced to a circular loop 6 inches in diameter. Valves of this type have been tested through 225 cycles of freezing and thawing with a gas pressure of 20 p.s.i. applied after each cycle without leakage (determined by gas collection) or dimensional change (determined by micrometer). Leakage was also looked for, using a halogen leak detector and Freon gas. KO leakage was found even at pressures of 100 p.s.i. A common failing in design is vents which are too small. Vents 1 inch in diameter were satisfactory for elevation changes of not more than 3 or 4 feet. To avoid siphoning, vents 4 inches in diameter are required if the salt falls 17 feet. The possibility of avoiding plugging of the vents with salt forced u p into them was tested by inserting a t the top of the vent a filter of porous metal which allowed gas to flow freely but when cold, would not allow salt to flow. Salt was intentionally pressurized into the cold vent so that it became plugged. The vent VOL. 51, NO. 2
FEBRUARY 1959
169
Figure 1. Data for 12inch vessel agree with theory
13.0
I
11.0
90
-
q = GAS RATE, cfrr E = EFFICIENCY. % A,B = CONSTANTS
b
I
i
u
E W
is 26 24
I
,
I
I
-e
5 Ocfm
2o -; 22
__
18
16
1
-
-2
tiFigure 2. Reaction efficiency improves with increase in draft tube diameter
I l - I N - P I A DRAFT TUBE
70-
60
4
I
\ 0
Aq" + E
WHERE
j/
WI 8 0 -IN
E
,
3 0 ,
(4
0
2 3 4 D R A F T TUBE DIAMETER ( i n )
1
3-IN-DIA DRAFT TUBE
5
30 DILUENT-AIR
I
20
I
0
IO
I
I
20
30
was cleared easily by heating it above the melting point of the salt and applying gas pressure to the vent line. Other freeze valves worked satisfactorily on smaller pipes. A conebottom freeze valve worked well with l/r-inch tubing. This valve had a holdup of only a teaspoonful of salt and held gas pressure in each of five tests. A valve similar except for a cylindrical instead of a cone bottom held in 30 out of 31 tests with '/r-inch tubing but failed to seal '/2-inch pipe. Fused Salt-Gas Reactions
.
The objectives in the reaction of gases with fused salts are a rapid complete reaction to minimize corrosion time, no salt entrainment, low maintenance, and low gas consumption. T h e corrosion rate is greatly enhanced by high temperature operation. The criterion of low maintenance precludes the use of mechanical stirrers or recirculating systems; the problem is to find the means of achieving the best reaction efficiency in a mechanically unstirred pot. To speed u p the chemical reaction the gas phase should be well dispersed and as much turbulence as possible provided in the gas and liquid phases At the same time it is necessary to provide for bulk flow of the melt within the pot, so that all the melt will contact the gas for complete reaction (to 99.999%). Rushton (27) has pointed out that a unit of energy imparted to a mixture can provide either bulk flow or fine scale turbulence, but these two are mutually exclusive. The problem thus is refined to the point of determining conditions that will provide the optimum balance between bulk flow and fine scale mixing. Equipment tested for this purpose included a dip tube sparger, a percolator
170
Figure 3. Reaction efficiency is improved by increased carbon dioxide in gas stream 22 20
40
60
tube, and a sieve plate. Because of the numerous technical difficulties of working with a molten salt system, extensive testing was done with a carbon dioxideaqueous sodium hydroxide system. Confirmatory tests are being carried out with fluorine in a fused salt. Recommended Equipment. For plant operation the percolator tube (draft tube) was recommended. The diameter of the draft tube should be '/z to 3 / 4 of the diameter of the reaction vessel, if the vessel is not otherwise crowded. T h e draft tube should be completely submerged and, in fact, need not come up to the liquid level, but the bottom of the draft tube should come to within 1 inch of the bottom of the vessel. Baffling of the draft tube with disk-and-doughnut baffles is desirable. The use of a thick-walled draft tube which may be sacrificially corroded prolongs the life of the vessel and makes its use more attractive. Theory of Contacting Efficiency in Bubble Beds. An equation relating contacting efficiency to gas rate for any given contactor was derived by Holland (8). I t was assumed that the reaction was heterogeneous and that the rate of reaction was proportional to the number of gas molecules striking a unit of liquid surface in unit time, to the amount of liquid surface surrounding a bubble, and to the mole fraction of reactant in the liquid surface exposed to a gas bubble. I t was also assumed that the frequency of bubble formation and rate of bubble rise were constant and that the bubble
INDUSTRIAL AND ENGINEERING CHEMISTRY
100
80
G O 2 CONCENTRATION IN G A S S T R E I M
(%I
reached its terminal velocity immediately. For gas rates of engineering interest experimental evidence indicates that these assumptions are valid. Evaluating the reaction rate experimentally, the following equation was obtained :
where E is the contacting efficiency, q is the gas rate (in cubic feet per minute), and A and B are constants which depend on the type of contactor used. Data for a variety of contacting devices were correlated by this equation at gas rates greater than 0.5 cubic foot per minute (Figure 1).
Table I. Effect of Tank Geometry on Gas Utilization Efficiency A tall narrow is better than a short wide vessel
Gas Liquid Contactor Gas Flow Rate, Cu. Feet/ Min. 0.25 0.5 1 .o 2.0 3.0 4.0 5.0
COz, measured a t Z O O C. and 1 atm. 45 liters water containing 1 mole NaOH '/pinch diameter dip tube located on tank axis Gas Utilization
- Efficiency. yo 12-in. vessel
6-in. vessel
35.3 32.4 32.4 29.5 33.9 30.8 31.4
81.9 73.9 64.0 58.5 55.6 51.2 49.8
FLUORIDE V O L A T I L I T Y Effect of Variables on Reaction Efficiency. Many variables influence the contacting efficiency in an unstirred pot. Most important were the position of the top of the draft tube with respect to the liquid level in the vessel; the ratio of vessel height to diameter; the influence of mixing from other bubble streams in the vessel or impedance to mixing by structural members in the vessel ; and the physical properties of the liquid. At gas rates below 1 .O cubic foot per minute the diameter of the draft tube was unimportant, but a t higher gas rates the reaction efficiency improved as the draft tube diameter increased (Figure 2), as the result of the decrease in fluid friction. Several draft tubes \yere tried, identical except that they were cut off a t different points below the liquid surface, which was kept constant. The decrease in efficiency caused by shortening an 1@/4inch draft tube to l & / 4 inches was less than the scatter of the data. The vessel shape for high temperature operation is generally fixed by the design of furnaces to maintain the temperatures required. From the point of view of gas-liquid contact efficiency, a tall, narrow vessel is preferable to a short wide vessel, as a longer path is provided for the gas (Table I). Contacting efficiency was improved by auxiliary stirring of the vessel contents with nitrogen bubbles from liquid-level and specific-gravity dip probes outside the draft tube. This auxiliary stirring was of greater benefit when the liquid had a high viscosity or a baffled draft tube was used. The limit of improvement to be expected from auxiliary stirring was determined by the use of a mechanical stirrer ouiside the draft tube. At a gas rate of 0.25 cubic foot per minute a mechanical mixer increased the efficiency from 34 to 587G, a t 1.5 cubic feet per minute, from 28 to 56Yc. However, addition of air to the stream of reacting gas passing through the draft tube in an attempt to increase the bulk flow in the vessel caused a net decrease in reaction rate (Figure 3), probably because of dilution of the carbon dioxide.
Table II.
Disk-and-doughnut baffles inserted in the draft tube in an attempt to increase fine scale turbulence were useful a t low gas rates (below 0.5 cubic foot per minute), but decreased efficiency a t higher gas rates (Figure 4). This effect was more pronounced in a solution whose viscosity was 20 centipoises than in a n aqueous solution. The effect of viscosity was to lower the efficiency at most gas rates for all contacting devices. T h e gas inlet configuration, the location of the dip tube with respect to the vessel axis, and the orientation of the dip tube outlet (whether downward or horizontal) were of little consequence. The use of percolator tube devices for promotion of bulk flow in tanks holding u p to many thousands of gallons was investigated at Hanford (3); those data provide a n extension of data presented in this discussion. Distillation
of Inorganic Substances
T h e problem in the design of equipment for distilling inorganic materials is whether or not the distillation of these substances, which have a much higher specific gravity than substances ordinarily distilled in practice, may be defined by the same design methods as those generally applied fos ordinary substances. Limited tests were made of flooding rates, pressure drop, holdup and separation efficiency for uranium hexafluoride, interhalogens, dense fluoroorganic compounds, and some other inorganic compounds in packed columns and in sieve plate columns. I t was found that flooding and pressure drop can be predicted by modifying the usual design equations to account for the physical properties of the substances being distilled. Holdup has also been correlated \vi th throughput by the Jesser-Elgin equation, but the reliability of the correlation is questionable. The H E T P (height equivalent to a theoretical plate) for inorganic substances appears to be about double that for organic substances. Flooding Rates. Flooding rates of inorganic compounds were correlated with the physical properties of the sub-
Flooding Rates for Dense Substances
Most loboratory columns provide too little heat input to reach flooding
Compound
Boilup Rate Column at Total Reflux, Diameter, Lb./Sq. Ft./Hr. Inches
Packing
Ref.
Column Flooded UFa UFs BrF3
1500-2000
0.5
4950 (calcd.)
0.87
3900
2.0
Ni Heli-Pak l/s-in. Ni Heli-Pak l/sz-in. Ni helices ~/I&L
Column Not Flooded UFs UFa UFs-CsFia
2380 3350 5580
0.75
0.87 5.05
l/s-in. Ni Heli-Pak '/a-in. Ni Reli-Pak S/s-in. Monel Raschig rings
(7)
(f4 )
(10)
stances distilled and with the dimensions of the distillation equipment by the graphical method of Lobo and others ( 7 7) as well as by a modification of the Sarchet correlation (22) to allow for differences in physical properties. T h e flooding rate of a column is characterized by a marked increase in the amount of liquid which is held u p in the column and impedes the flow of the vapor phase. The holdup of liquid in the interstices of the packing would be expected to increase with increasing viscosity and surface tension and with decreasing density. Because metal salt systems are generally characterized by high density and low surface tension, flooding rates would be expected to be somewhat higher than those for organic compounds, even though the viscositim are somewhat higher. These higher flooding rates have been borne out by experience. Density and viscosity corrections to the liquid and vapor phase flow rates make it possible to correlate flooding rates for uranium hexafluoride with those for less dense material. Actual flooding data with uranium hexafluoride are rare, as most laboratory columns do not provide for sufficient heat input for the flooding rate to be reached (Table 11). The most extensive flooding study reported (74) was that made by McGill in a glass column 0.87 inch in diameter, packed with I,'*inch nickel Heli-Pak. McGill was not able actually to flood the column with uranium hexafluoride, but a uranium hexafluoride flooding rate which he calculated from an equation by Bertetti (7) seemed reasonable. The most satisfactory correlation for predicting flooding rates seems to be the curve of Sherwood, Shipley, and Holloway (23) as modified by Lobo and others (77). However, its use requires a knowledge of the packing surface area and the percentage ofvoids; because this was not known for the Heli-Pak packing used by McGill, the correlation of Lobo and others could not be applied. Sarchet (22) suggested plotting G/$ as ordinate against L$,/G as abscissa logarithmically, where G = vapor flow rate at flooding, pounds per sq. foot per hour; L = liquid flow rate at flooding, pounds per sq. foot .per hour; d = (p~/0.075)1/?; and pG = density of vapor, pounds per cu. foot. H e found that for a given type and size of packing the curve was characteristic. The points on the curve may be determined by plotting the flooding rates of different substances or the flooding rates of a given substance at different reflux ratios. Pigford and Colburn (79, p. 683) suggested corrections for variations in viscosity and densit>-. Applying these corrections makes the G 62 3 1'2 ordinate 4 vn and the abscissa
(-+)
VOL. 51, NO. 2
0
FEBRUARY 1959
171
,
( X 102) 10
0.05
0.03
0.1
0.2
0.5
1.0
2.0
1 4
5.0 I
Cog RATE (cfm at ZO'C, I a t m )
.
i
3
5
6
1 7 8 9 j O
L
Ll/623
Figure 4. Increased viscosity lowers efficiency in all contact devices
L 62,3
,,2,
m(, 1 of liquid,
where n is a function of liquid flow rate, varying from 0.42 a t L = 4000 pounds per sq. foot per hour to 0.13 at L = 24,000 pounds per sq. foot per hour. McGill's data (74)were analyzed by substituting known values for UFe, C a I B , and nheptane in this equation (water holdup
172
5
Figure 5. Flooding rates for dense substances may be predicted by correcting for differences in viscosity and density
where v = kinematicviscosity
centistokes; p L = density of liquid, pounds per cubic foot; and n = function of packing size. A value of 0.5 for n was estimated for Fenske helices; subsequently it was found that the use of smaller values for larger packing did not appear to be justified for uranium hexafluoride distillation until confirmed by experimental measurements with such packing. The shape of a plot of McGill's flooding rates on these modified coordinates (Figure 5) agrees fairly well with that of the curves given by Sarchet. No other cases of actual flooding have been recorded. Workers at the Oak Ridge Gaseous Diffusion Plant, using a 6-inch-diameter column packed with Raschig rings and a 2-inch-diameter column packed with Cannon protruded packing, concluded that the correlation of Lobo and others may be used satisfactorily . Pressure Drop. The only measurement of pressure drop for inorganic distillations found in the literature was for the distillation of bromine trifluoride in a 2-inch-diameter column packed with 6/se-inch nickel helices ( 7 8 ) . As the holdup was not measured in the bromine trifluoride study, the form of the Reedand Fenske equation (20) neglecting holdup was applied (Figure 6). The line drawn through the plotted points was a straight line of slope n = 1.9 and intercept k = 0.33. This slope is slightly higher than the expected value of 1.7 to'l.8. Holdup. The Jesser and Elgin equation (9) for determining liquid holdup in terms of a reference liquid, water, is:
+v
Vapor rate, Ib./rq. ft./hr. 0. (pc/0.075)'/:. PO. Vopor density, Ib./cu. ft. PL. Liquid density, Ib./cu. ft. v. Kinematic viscosity of liquid, centisakes. 1. Liquid flow rate, Ib./sq. ft./hr. Data from Page and others (78). 0 Data from McGill ( 7 4). Curve for Raschig rings from Sarchet (22)
G.
for the Heli-Pak was considered to be identical with that for 0.39-inch rings, though the values are probably low). n was then solved for and plotted against the liquid flow rate (Figure 7). McGill adapted the Jesser-Elgin equation by using C8FlB as the reference liquid, which eliminated any uncertainty as to the holdup in the Heli-Pak packing for the reference substance. The values of n obtained in this way are also plotted in Figure 7. I t was thus demonstrated that extrapolation of the line recommended by Jesser and Elgin to the range of liquid flow rates obtained in distillation disagrees with the experimental results of McGill, but that McGill's results are internally consistent. The location of the points for n-heptane indicates that at lower liquid rates the values of n deviate from a straight line, perhaps going through a maximum and then decreasing at still lower liquid rates. Column Efficiency. The H E T P of packed columns in which UF,, is distilled is about twice that obtained from the same column distilling mixtures of hydrocarbons. Because the design height of a column is determined by the product of the number of theoretical plates (from vapor-liquid equilibrium data) and the HETP, it is desirable to determine the H E T P for a given system and packing, to avoid large safety factors, making for exorbitant column heights. Calculation of distillation efficiency for metal salts has not been possible but some experimental comparisons between these systems and hydrocarbon systems are available. At Brookhaven (78), 6/32-inch aluminum helices produced an H E T P of 3.2 inches or more for a mixture of n-heptane and methylcyclohexane in a 2-inch column. In the same column, a mixture
INDUSTRIAL AND ENGINEERING CHEMISTRY
of bromine trifluoride and uranium hexafluoride gave H E T P values from 4.5 to 6.3 inches. Tongberg, Quiggle, and Fenske (25), using the same packing in a smaller column, obtained for the nheptane-methylcyclohexane mixture H E T P values from 4.1 to 5.4 inches. O n the other hand, tests at Argonne National Laboratory on a 1.75-inch column packed with helices gave an H E T P of about 8 inches with a bromine trifluoride-uranium hexafluoride mixture and only 2.0 inches with the n-heptanemethylcyclohexane mixture (75). A pilot plant a t Oak Ridge Gaseous Diffusion Plant (70) indicated that 5/ginch metal rings gave H E T P values of 14.4 inches in separating uranium hexafluoride from CSFIC. No other information on H E T P is available for metal rings, but for '/*-inch ceramic rings, the separation of n-heptane and methylcyclohexane showed H E T P values of 6.0 to 8.4 inches. I t is concluded that at present the values of H E T P for systems involving U F Oor other dense substances may best be found by doubling the value obtained for hydrocarbon systems. Work reported to date has been carried out well below flooding; at higher boilup rates lower values of H E T P may be found. Application of Perforated Plate Columns. Some information is available on the distillation of inorganic substances in perforated (sieve) plate columns. Three laboratories studied the separation of hafnium from zirconium by differences in volatility of the complexes 3ZrC14 - 2POC13 and 3HfC14 - 2POC13. Gruen and Katz (6) used a 50-plate Oldershaw column, an all-glass column about 1 inch in diameter with the perforated plates a t 1-inch intervals. Each
FLUORIDE V O L A T I L I T Y 3
0.9
2
0.8
+ z
3.7
W
Z
,I“
0
1
C.6
W
n “ ,
z 0 ul z 05
a
4
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w
k
w
N
u 4
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O5
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cc
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0.4
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ro W
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0.2
0.2
o.. j 500
300
1000
2c00
50c0
VCPOR FLOW ECTE V b / f i ‘ - h r )
0.1
A G/PL,S
Figure 6. Pressure drop is low, but i t s change with throughput i s about right Column diameter.
2.0 inches. Packing.
-
6/winch aluminum helices.
Data from Page and others ( I 8). pc. Vapor density. AP. Avera g e pressure drop, Ib./sq. ft. h. Depth of packing, feet. f. Fraction voids in pocking. M L . l i q u i d viscosity, Ib./ft.-hr. S. Packing surface, sq. ft./cu. ft. G. Vapor flow rate, Ib./sq. ft./hr. g. Gravitational constant, feet/sec.’
plate contained 82 0.3-mm. holes. They found a plate efficiency of 3470 or a n HETP of 8.5 cm. For a column of similar dimensions but packed with I/*inch glass helices, the HETP was 10 cm. T h e HETP of a n Oldershaw column for ordinary organic liquids is about 4.2 cm., just half that for the inorganic system. T h e Foote Mineral Co. carried out the separation in a 1-inch Oldershaw column and then in a 4-inch glass perforated plate column (77). They did not report plate efficiencies, b u t stated that, instead of 16 times as much capacity as the 1-inch column, the 4-inch column had a capacity only six times as great. At the University of Louisville, a column 4 inches in diameter was constructed of Type 304 stainless steel (26). Thirty-two plates, each with 25 holes ‘/4 inch in diameter, were spaced 3 inches apart. T h e plate efficiency was 53y0 with throughputs of u p to 4400 pounds per sq. foot per hour. While the few7 data reported are reinforced by considerable operating experience which permits some degree of confidence in designs based on the above conclusions, the paucity of data demonstrates the need for more extensive basic research in the behavior of these new substances in distillation equipment. A
Figure 7. Importance of surface tension diminishes at lower vapor rates
more complete discussion of the available information on distillation of dense substances is presented elsewhere (72). Acknowledgment Thanks are due to Guy Jones, Jr., S. H. Stainker, and J. L. Whitten for helping collect data on molten salt handling and gas-liquid contacting, and to many individuals a t other laboratories mentioned who reported the data on distillation. literature Cited (1) Bertetti, J. W., Trans. Am. Inst. Chem Engrs. 38, 1023 (1942). (2) Cathers, G. I., “Uranium Recovery from Spent Fuel by Dissolution in Fused Salt and Fluorination,” American Nuclear Society Winter Meeting, Washington, D. C., Dec. 10-12, 1956. (3) Cook, M. W., Waters, E. D., U. S. Atomic Energy Comm., Rept. HW39432 (Dec. 1, 1955). (4) Foltz, J. R., Zbid., NAA-SR-273, 20-3 (Dec. 1, 1953). (5) Goodman, E. I., private communication to E. L. Nicholson, 1954. (6) Gruen, D. M., Katz, J. J., U. S. Atomic Energy Comm. Rept. ANL-4269 (March 22, 1949). (7) Gustison, R. A.,. private communica_ tion, 1954. (8) Holland, C. D., U. S . Atomic Energy ORNL-CF-56-10-83 Comm. Rept. (October 1956). (9) Jesser, B. W., Elgin, J. C., Trans. Am. Inst. Chem. Engrs. 39, 277 (1943).
(10) Kurtz, J. J., hkTapgart, L. E., Rothfleisch, J. E., Spaldine, J . D., U. S. Atomic Energy Comm., Rept. KDD-490
(Feb. 27, 1953). (11) Lobo, W. E., Friend, L., Hashmall, F.. Zenz. F.. Trans. Am, Inst. Chem. Engrs. 41,’ 693 (1945’). (12) Long, J. T., U . S. .4tomic Energy Comm., Rept. ORNL-1738 (.ALI~. 10, 1954). (13) Zbid., ORNL-2539, in preparation. (14) %Gill, R. M., Ibid., K-775 (July 2 , 1951). (151 Mecham. W. J.. Liiniatainen. R . C.. ‘ Kessie, R. k., Sekfeldt, \V. B:, Chem. Engr. Progr. 53, 72F (1957’1. (16) Milford, R. P., IND.h”.ckn“ 50, 187 (1958). 117) Opburn. S. C.. Jr.. Fisher. H. A i . . U. g. .4tomic Energi Comm., Rept: NYO-1088 (Aug. 18, 1950). (18) Page, W. K., Raseman, C . J., Goodman, E. I., Scarlett, C. H., Chem. Engr. Progr. 51, 566 (1955). (19) Perry, J. H., “Chemical E,ngineers Handbook,” 3rd ed., hicGra\v-Hill, New York, 1950. (20) Reed, T. M., 111, Fenske, h i . R . , IXD.ENG.CHEM. 42, 654 (1950). (21) Rushton, J. H., Cham. Engr. Progr. 50, 587 (1954). (22) Sarchet, B. R., Trans. Am. Imt. Chem. Engrs. 38, 283 (1942). (23) Sherwood, T. K., Shipley, G. €I., Holloway, F. -4.L., IND.EXCLCHEM. 30, 765 (1938). (24) Smiley, S. H., Brater, D. C . , Littlefield, C. C., Pashley, J. H., Zbid., 191 (1959). (25) Tongberg, C. O., Quiggle, I)., Fenske, M. R., Zbid., 26,1213 (1934’1. (26) Williams, G. C., Galginaitis, S. V., Baker, E. G., Jr., Isaacs, .4.H., Holzknecht, E. W., Gillespie, R. A.. Moody, R. G., Graham, L. A,, U. S. .Atomic Energy Comm., Rept. N Y 0 0 - 1 0 0 9 (Aug. 1, 1950). RECEIVED for review May 26, 1958 ACCEPTED October 13, 1958 Division of Industrial and Engineering Chemistry, Symposium on Chemistry and Reprocessing of Circulating Nuclear Reactor Fuels, 133rd Meeting, ACS, San Francisco, Calif., April 1958. VOL. 51, NO. 2
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