Liquid Extraction Techniques & Practice

R O B E R T E . T R E Y B A L

LIQUID EXTRACTION TECHNIQUES AND PRACTICE

Extractive reactioniemouing product from a reaction

mixture as it f o r m s i e c e i v e s major attention.

delves into reaction details and mechanisms

Signgcant research

ndustrial application of liquid extraction has moved I ahead rapidly in several areas, most notably in the field of petroleum refining. It is particularly useful for separating aromatic hydrpcarbons from catalytically reformed naphthas. These naphthas yield benzene, toluene, and xylene. With the American petrochemical industry rapidly reaching an annual production capacity of 600 million gallons of benzene, liquid extraction has become a major separation process.

Most of the new installations for aromatic hydrocarbons use the Udex process, a diethylene glycol extraction of the aromatics from the reformed naphthas. Catalytic dealkylation of toluene and xylene to produce benzene, a process which has become increasingly important, also requires concentration of the aromatic hydrocarbons. Extraction has become the major method for doing this.

Isobutylene will be concentrated by selective solvent extraction in a process recently licensed by an American fum from France rather than by conventional sulfuric acid treatment. The solvent has not been publicly identified. A new plant for propane deasphalting uses three 70-foot tall RDC extractors, possibly the largest such devices ever built.

In the nonpetroleum organic chemical field, the most noteworthy news is the industrial extraction of acetic and formic acids from pulp-mill black liquor. Methyl ethyl ketone is the solvent. The extractor is very large, 100 feet tall, and of special design. Details have not heen disclosed.

In the inorganic chemical industry, interest in the butanol extraction of phosphoric acid remains high, as an important means of producing a concentrated product for fertilizer manufacture. New extraction processes have been announced by the Oak Ridge National Lab- oratory for separating beryllium from its ores, for separation of yttrium-cerium, strontium-9kalcium, and for the production of technetium-99. Niobium-tantalum extraction separations are now routine, carried out by several firms.

(Continued on page 56)

V O L 5 4 NO. 5 M A Y 1 9 6 2 5 5

In the review of the unit operations aspects of extraction which follows, the literature search ended about December 1, 1961. I t should be understood that the reduced number of literature citations in no way re- flects the activity in this field, which on the contrary has continued to increase steadily for many years.

EQU I PM ENT

Mixer-Settlers. When a radioactive solute such as uranyl nitrate is present in an aqueous liquid which is agitated with an organic liquid containing a scintillant, the a-particles generate light within a very short distance from the interface, and this can be used to measure the interfacial area (5A). The results do not agree with those of previous work. This might conceivably be due to surface effects caused by the dissolved solutes. Church and Shinnar (6A, 40-4) have continued their theoretical studies of the behavior of liquid dispersions in agitated vessles, using the concept of local isotropy to establish conditions for drop breakup and coalescence. The presence or absence of coalescence was demonstrated by the spread, or lack of spread, of color from a small batch of colored dispersed-phase particles added to an uncolored dispersion. Coalescence in agitated dispersions was also demonstrated by observing the difference in size of droplets in different parts of the vessel (48A). Drop size was measured by light scattering. Drops become larger as the distance from the agitating impeller increased. This was particularly true for systems of low interfacial tension and large differences in the liquid viscosities. Coalescence and redispersion of water mixed with benzene, as measured by a chemical reaction technique, was negligible (32A).

Drop sizes characteristic of air-agitated two-liquid dispersions were also studied (45A). Practical application in uranium extraction is suggested (2A). In con- nection with his studies of extractive chemical reactions, Trambouze measured the time for the dispersed-phase holdup in a continuously operated agitated vessel to reach steady state (9B). A design method which relates drop size to operating variables does not require geometric and dynamic similarity for scale up (17A).

AUTHOR Robert E. Treybal i s Professor of Chemical Engineering at lVew York University and has authored many highly regarded books on liquid extraction dealing with both theory and practice. H e has authored IG1ECs Liquid Extrac- tion reuiew since 7951.

Earlier work on the interfacial area developed by passing two immiscible liquids through an orifice has been extended (30A4) to cover a wide range of pipe sizes, liquid properties, and flow rates. The degree of dispersion in such situations can be related to the rate of energy dissipation per unit mass (41A). Another study of orifice dispersions (7A) was particularly con- cerned with the development of light-transmission appa- ratus for characterizing the dispersions.

An estimate of the effective diffusivity for drops of kerosine dispersed in water, with butyl amine as extracted solute (344) for marine propellers and spiral turbines as agitators, produced values averaging about the same as the molecular diffusivity, indicating noncirculating drops. For flat-blade turbines and the same chemical system, the effective diffusivity averages two to three times the molecular value. Reasons for the difference remain obscure.

The relative efficiencies of mixing for various mixer designs in a pump-mix mixer-settler can be determined from the over-all rate of heat (rather than mass) transfer between the mixed liquids (9A), although the data cannot be readily converted to solute extraction rates. A more detailed report (39A) of an earlier publication on uranium mixer-settler extraction is now available. In recovering uranium from ore leach liquors, it is desirable to be able to extract the unclarified liquors directly, thus saving the cost of clarification. Unfortunately the slime particles stabilize the emulsion which forms. This can be prevented by adding small amounts of hydrophilic polycationic materials, specifications for which have been disclosed (1 6A). An excellently detailed process report on bench-scale mixer-settler extraction of uranium is also available (42A).

Several studies have been published of mixer-settlers which do not use the conventional stirred vessel as a mixer, In the Fenske-Long extractor, mixing is done by reciprocating perforated plates. Scale-up for such extractors is demonstrated (29A), even up to a 15-foot diameter tower, a 6-inch slice of which was operated. Somewhat larger mixing intensities are required in the large scale for the same efficiencies. In this report, a transfer unit is defined in terms of a driving force based, not on interfacial compositions, but rather on the bulk equilibrium concentrations reached by the effluent liquids if the stage efficiency were 1 0 0 ~ o .

The spouted mixer-settler, consisting of a jet of heavy liquid squirted upward into a bulk of light liquid, allows mixing and settling to occur in the same vessel (19A). High stage efficiencies are attainable. Packed towers operated with cocurrent flow of the liquids are a form of line mixer, the packing substituting for an orifice or nozzle (26A). A small device of this sort was demonstrated to lead to high stage efficiencies.

Several new mixer-settler extractors have been described which are variants of the conventional designs (24.4, 49A). One (31,4) is air-pulsed (not air agitated), which makes it particularly useful for radioactive solutions.

56 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y

A review of the status of design methods for mixers (47A) emphasized the many factors which still require research.

Application of the holdup-slip velocity characteristics of fluidized solids to liquid-liquid systems has been extended for spray towers to continuous countercurrent flow (3A). The concept is restricted, however, to nonflooded conditions. This makes it possible to com- pute dispersed-phase holdup and interfacial area in such towers at all useful rates of flow.

Expressions for the over-all mass-transfer coefficient for single drops, arranged in the usual fashion as products of a variety of dimensionless groups raised to empirically determined exponents, were applied to single-drop extractions of the lower fatty acids between benzene and water (27A). The Sherwood number here becomes the Kirpechev No. These are to be descriptive of spray tower extractions, but use of the distribution coefficient as one of the dimensionless numbers to ex- press the role of the individual-phase coefficients is likely to reduce the general utility of the expressions. Experi- ments with a small (2.5-inch diameter) spray tower (37A) showed heights of transfer units to be 2 to 5 . 5 times those obtainable in packed towers. An effect of direction of extraction was ascribed to differences in interfacial area, Drop coalescence, which results in variations in drop-rise velocities, in effect produced a dispersed- phase backmixing. Experiments with butanol-water in a smaller tower (1A) showed both continuous- and dispersed-phase volumetric coefficients to be essentially independent of continuous phase flow rates, which agrees generally with other experiences.

Spray columns are reasonably efficient, nonfouling heat exchangers for two immiscible liquids if direct con- tact is permissible. Their low cost makes them attrac- tive for sea-water desalting processes (50A). Some new data from 4-inch diameter columns operated with sea water and hydrocarbon oils confirm the fact that heat- transfer coefficients are good, especially with low viscosity oils.

Packed Towers. Some new, and some old, holdup data from small packed towers were correlated empirically by an expression related to flooding in such towers (18A). But there seems to be little improvement over the simpler, slip-characteristic velocity methods of Pratt. The latter were successfully utilized, in modified form, for a variety of systems in towers, 2 to 12 inches in diameter (43A).

New mass-transfer data from small (1.88-inch diameter) columns were offered (38A). The packings were smaller than the critical size. In somewhat smaller columns (23A), over-all area-based mass- transfer coefficients for toluene-heptane-diethylene glycol, a simplified Udex-process system, were essentially independent of flow rates. This agrees reasonably well with other experiences. Further, the same area coefficient was obtained as with gentle mechanical stirring (12C). The area coefficient is also essentially constant for the two-component system, toluene-

Spray Towers.

C i r c l e No. 12 on Readers' Service Card '401. 5 4 NO. 5 M A Y 1 9 6 2 57

For liquid extraction, computers prove practical in mass and heat transfer studies . .. , ... . .. ..... .

'i. _..:_

packings for liquid extraction were described (28A). Rotating-Disk Columns. Dispused-phase holdup, meas-

ured by a radioactive tracer technique for toluene-water in columns of several internal geometries (25A) generally confinned the earlier F'ratt slip-characteristic velocity relationship. Some modification results hom a wider range of geometric configurations. An empirical cor- rection to the slip velocity relationship is necessary for small differences in disk and rotor diameters. The characteristic velocity is not a constanf a t high peripheral speeds of the rotor.

A description of Shell Oil's installation of two 8-foot diameter RDC's for propane deasphalting has been made available (46A). A study of the importance of relative wettabdity of the stator and rotor surfaces developed that these should be preferentially wetted by the continuous phase for best performance, much as in packed towers (1OA). Addition of a surface-active agent to reduce the sue of the dispersed water drops was also useful, but this technique would have to be used cautiously, because rates of extraction are frequently retarded by such agents. In a modification of the stand- ard design, the agitated liquids flow from the main section of the column to a chamber protected from the action of the rotating disks for countercurrent flow from one compartment to the next (33A). Here the dispersed liquid has opportunity to coalesce before being dispersed. This arrangement could presumably reduce backmixing considerably.

Recommendations for estimat- ing the interface level for o v d o w of the dispersed phase, allowing for pressure drop through the plates and down- comers, have been outlined in some detail (35A).

Pulsed Columns. The electrical conductivity of a liquid-liquid dispersion is a measure of the dispersed- phase holdup, provided the drops are small and uni- formly spherical (11A). This permits the measurement of holdup in a pulsed column without disturbing its operation (12A). The variation in holdup with pulse frequency, flow rates, and with vertical position in the column was determined in this way.

Up to amplitudes of 25 mm. and frequencies of 240 cycles per minute, the efficiency of phenol extraction horn several organic solvents was proportional to the product of frequency and amplitude (20A). In the extraction of uranyl nitrate, the interfacial tension and density differences as influenced by the concentration of tributyl phosphate in the hydrocarbon solvent are important; a concentration of 20 to 30% by volume seems best (13A). With the system, methylisobutyl ketone-acetic acid-water, plates of polyethylene with ketone continuous provided the best extraction rates in a 2-inch diameter column (44A). Stainless steel

Pafmafcd Plote Towers.

58 INDUSTRIAL AND ENGINEERING CHEMISTRY

. . . . .

plates, with either phase continuous. were much less effective. Transfer i f the acid from ketone to water provides better rates than transfer in the opposite direction.

In pulsed packed columns, with Raschig rings sup- ported on perforated metal plates, uranium extracted from nitric acid into a hydrocarbon solution of tributyl phosphate, there was no effect of column diameter in the range 10 to 20 cm. (22A). Mass-transfer rates were fairly constant with increased pulse frequency, but increased with pulse amplitude. For a phase ratio of unity, either phase may be dispersed without appreciable influence on the mass-transfer rate. For a ratio of four, larger rates were obtained with the majority (organic) phase dispersed (21A).

A new method of pulsing, periodically introducing compressed air into the liquid flow, has been described (36A). Air consumption depends on the frequency and amplitude of pulsing and the pressure in the pulse line. General methods for design of pulse columns were reviewed (EA).

Other. Work on the injector column previously mentioned in these reviews continues in the Soviet Union (15A), with the measurement of end effects which increase with rate of flow of the solvent.

A very complete review of equipment and its characteristics, as well as of the principles of liquid extraction, particularly as applied to the processing of nuclear reactor fuels, is available in an excellent new bwk (14A).

CALCULATION MnHODS

In computing the number of stages required in a fractional extraction, graphical procedures can handle two distributed solutes even when their distributions are interdependent. In the latter case a trial and error pro- cedure is needed. When a large number of distributed components are present, hand calculations become so tedious as to be impracticable, even for cases where equilibrium distribution can be expressed mathe- matically. High-speed digital computers, however, can handle these, and a program for separating metal nitrates with tributyl phosphate has been developed (6B). Some hitherto unrealized and as yet uncalculable conditions evidently govern the minimum solvent ratios in such cases. A digital computer was also used to study the dynamic characteristics of a pulsed extractor (lB), and the application of analog computers to stage calculations has been demonstrated (3B). A computer was also used to develop the cost-response characteristics and the optimum conditions for a process involving antibiotic extraction from the data of a Za-fractional design ofexperiments (5B).

(Conrimmi on page 60)

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VOL. 5 4 NO. 5 M A Y 1 9 6 2 59

Research in liquid extraction

delves deeper into

In countercurrent extraction with ternary systems, where there is appreciable chaige in the mutual snlu- bility of the solvents with changing solute concentration, all three components are actively involved in interphase mass transfer. The concentration profiles for such a case have been examined by computation (2B). The number of transfer units actually required may differ considerably from those calculated by ignoring this phe- nomenon. RafIinate reflux in any case of simple countercurrent extraction is without question useless (8B).

Extractive reaction, where yield of a chemical reaction is increased by simultaneous extraction of one of the products, has been relatively neglected by those con- cerned with either kinetics or extraction, but no longer. Trambouze, and Piret (9E11B) have developed methods for computing such cases where reaction rate controls and mass transfer are rapid, allowing for reaction to mcur in one or both phases, for a variety of flowsheets. Some experiments in pulsed packed and perforated- plate columns on the hydrolysis of acetic anhydride in the presence of benzene confirmed the methods (11B). When--mass-transfer rates are important, varying the ratio of liquids in an agitated extractor-reactor by re- cycling one of the phases may be useful (9B). When the reagents are initially present each in the separate phases, the location of the reaction zone in one or the other phase depends upon the relative rates of mass transfer and reaction, a mathematical study of which is provided by Scriven (7B). A practical application is given by Latourette and others (4B) in an excellent laboratory study of the epoxidation of an oil in a small packed column, operated countercurrently.

EXPERIMENTAL FUNDAMENTALS

In recent years the realization that a direct application of the two-resistance theory of Whitman to liquid extraction, with the gathering of mass-transfer coefficients from typical equipment types, is far too great a simplification of the problem before us has gradually but inexorably become apparent. At first it was thought that if the mass-transfer coefficients could be expressed on an area rather than on a volume basis, the major difficulties would be solved. But it is increasingly clear that other phenomena, such as the respective d e s of molecular and eddy diffusion, interfacial turbulence, and interfacial mass-transfer resistance, even in those systems which are not chemically reacting are of major

60 I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y

importance. Wetted wall towen (19C) and disk columns (17C), so useful in gas-liquid studies, are used, but generally these offer difficulty in operation and in controlling the degree of turbulence. They have been largely replaced by transfer cells, which are gently stirred or otherwise agitated vessels where the interfacial area is controlled and measurable.

Experiments in this type ofcell by McManamey (13C), using two partially soluble liquids, were designed to reconcile the observations of J. B. Lewis that the mass- transfer coefficient, k, is independent of molecular diffusivity, D, and those of Cordon and Sherwwd that k varies as Do. in similar equipment, But k was found proportional to D a 9 so the question remains essentially unanswered. I t was suggested that the design of the vessel may influence the result. In similar experiments (13C) involving the transfer of metal nitrates from water to isobutyl alcohol, an appreciable interfacial resistance resulting from solvation of the solute was observed. Transfer in the opposite direction was enhanced by interfacial turbulence. In the transfer of iodine between aqueous KI and carbon tetrachloride, where the equilibrium 18- = I - + 1% is important, the initial transfer rate depends only on the concentration of 11, and is free of interfacial diffusional resistance (21C). Inter- facial turbulence is eliminated by using liquids in wn- centration equilibrium. Transfer rates may then be measured by substituting a radioactive isotope of the equilibrated solute in one of the phases and measuring its rate of transfer. Acetic acid containing radioactive carbon was transferred between two liquids between which the total acetic acid distribution was the equilibrium value (4C). The over-all mass-transfer coefficient then was observed to pass through a minimum as total concentration increased, and this was ascribed (but not proved to be related) to solvation of the solute on transfer and the effect of concentration on the

In the extraction of toluene from solution in diethylene glycol into heptane (12C), the mass-transfer resistance in the heptane phase is negligible, but an important interfacial resistance evidently exists. The constancy of the mass-transfer coefficient in the glycol solution, regardless of the toluene concentration and consequent viscosity, indicated that the viscosity corresponding to the solu- bility concentration controlled. Interfacial turbulence at nonequilibrium concentrations was evident.

Interfacial resistance was small when a jet of water passed through butanol (18C) and a surfactant had essentially no effect. A technique based on the Bruins- Cohen device for measuring diffusivity, where the amount of diffusion between two phases could be compared with that assuming the absence of interfacial resistance, revealed an appreciable amount of the latter in the transfer of acetic acid between toluene and water (2OC). In this case, the interfacial resistance increased markedly with increased concentration of a surfactant a t the interface, as measured by decreased interfacial tension. Others have observed no direct relation between these

(&rimed on poga 62)

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V O L . 5 4 NO. 5 M A Y 1 9 6 2 61

variabies, so that the role of surfactants is not clear. Interfacial turbulence, which may at times lead to strong surface disturbance (3C), may influence mass-transfer rates through an induced rate of surface renewal (14C). Kafarov has provided a review of some of these phenomena (1OC). Surface adsorption, which may or may not influence transfer rates, depending upon the cir- cumstances, can evidently lead on occasion to false equilibrium distribution data also (1 C) when separatory- funnel shake-outs are done so vigorously as to lead to very large interfacial area.

In the case of extraction from drops formed from jets of an immiscible liquid, the apparent effective diffusivity within the drops (considering them as equiva- lent to rigid spheres of higher-than-normal diffusivity) may be very large (16C). But it is difficult a t the present time to decide how much of this effect is apparent as a result of interfacial turbulence and how much due to orderly and expected circulation within the drops. Intermittently produced jets provide laryer mass- transfer rates than jets in continuous flow (1 5C). This no doubt contributes in part to the effectiveness of pulse columns.

The continuous-phase film coefficient for heat transfer between single liquid drops moving through a liquid can be determined from measured over-all rates provided a drop-surface temperature can be computed (6C). This was done for three different postulated internal drop motions (completely mixed, viscous circulation, and stagnant), and the measured data was fitted to an expression involving drop viscosity and interfacial tension as well as the usual continuous-phase properties. This is useful for nonoscillating drops (which appear to resemble completely mixed drops) whose viscosity does not exceed that of the continuous phase. The results may be applied to mass transfer cases, at least in the absence of interfacial phenomena.

The work of Garner (8C) has shown that oscillations of the drop, and particularly the wake, have important influence on the effect of Reynolds and Schmidt numbers on the outside coefficient. A demonstration of the applicability of the Kronig-Brink relation for transfer within circulating drops was also provided.

A mathematical study of the influence of internal circulation of nonoscillating drops on the continuous- phase coefficient in the absence of natural convection (2C) showed that at Peclet numbers of IO4, circulation may increase the coefficient by as much as threefold. But the effect is negligible at Peclet numbers below about 10. Actually, natural convection at low Peclet numbers may exert by far the predominating influence. In the extraction of acetic and butyric acids from solvent drops into aqueous base solutions (7C) , the concentration of the base may or may not influence the rate, depending upon the system.

Photographs of settling liquid drops have shown that the shift of the boundary-layer separation, related to the internal circulation, is the principal cause for their greater terminal velocity as compared with solid spheres (5C). The internal circulation, however, and

the terminal velocity are retarded by minute amounts of surface-active agents. Some additional new data are also available (9C). Kintner has shared his considerable experience in photographing moving drops by offering complete details of the techniques (1 lC) , including recommendations for best lighting, reflectors, camera f-stop values, and the like.

LITERATURE CITED

Equipment

(14) Astarita, G., Chim. e ind. (Milan) 43, 10 (1961). (2A) Atomic Energy of Canada, Ltd., Brit. Pat. 860,428 (Feb. 8,

(3A) Bayaert, B. O., Lapidus, L., Elgin, J. C., A . I . Ch. E. Journal

(4A) BrounshteYn, B. I., Bykova, L. G., PokorskiY, V. N., others,

(5A) Chester, C. V., Newman, J. S., U. S. Atomic Energy Comm.,

(6A) Church, J. M., Shinnar, R., IND. ENG. CHEM. 53, 479

(7A) Cingel, J. A., Knudsen, J. G., Landsberg, A,, Faruqui, A. A,

(SA) Damiani, L., Doria, A,, Fattore, V., Energia nudeare (Milan)

(9A) Davis, A. T., Colven, T. J., A . I. Ch. E. Journal 7, 72 (1961). (10A) Davis, J. T., Ritchie, I. M., Southward, D. C., Groupe

recherches prod. superficiellement actifs, Colloq., 5e, p. 61, Paris 1959.

(11A) Defives, D., Reed, C., Schneider, A,, GBnie chim. 84, 120 (1 960).

(12A) Defives, D., Schneider, A., Zbid., 85, 246 (1961). (13A) Durandet, J., Talmont, X., Bull. inform. sci. et tech. (Paris)

(14A) Fiagg. J. F. (ed.), Chemical Processing of Reactor Fuels,

(15A) Gclperin, N. I., Assmus, M. G., Khim. Prom. 1961, p. 269. (I6A) Goren, M. B. (to Kerr-McGee Oil Industries, Inc.), U. S.

(17A) Hills, B. A, , Brit. Chem. Enp. 6 , 104 (1961). (18A) Johnson, A. I., Levergne, E. A. L., Can. J . Chem. Eng. 39,

(19A) Johnston, T. R., Robinson, C. I V . , Cpstcin, N., Zbid.,

(20A) Kagan, S. Z. , Aerov, M. E., Volkova, T. S., Vostrikova,

(21A) Karpacheva, S. M., Rodionov, E. P., Popova, G. M., Ibid..

(22A) Karpacheva, S. M., Rozen, A. M., Vasilev, V. A,, Khim.

(23A) Kishinevskii, M. K., Mochalova, L. A., Zhur. Priklad.

(24A) Kotkas, R. E., Russ. Pat. 131,355 (Sept. 10, 1960). (25A) Kung, E., Beckmann, R. B., A . Z. Ch. E. Journal 7, 319

(26A) Leacock, J. A., Churchill, S. W., Zbid., 7, 196 (1961). (27A) Lileeva, A. K., Smirnov, N. I . , Zhur. Priklad. Khim. 34,

1158, 1361 (1961). (28A) Logsdail, D. H. (to United Kingdom Atomic Energy

Authority), Brit. Pat. 818,272 (Aug. 12, 1959). (29A) Long, R. B., Fenske, M. R., IND. END. CHEM. 53, 791

(1961). (30A) McDonough, J. A., Tomme, W. ~ J . , Holland, C. D., A . I.

Ch. E. Journal 6, 615 (1960). (31A) Mathers, W. G., Winter, E. E., Cornett, L. G., others,

Atomic Energy of Canada, Ltd., CRCE-980, 1960. (32A) Matsuzawa, H., Miyauchi, T., Kagaku Kogaku 25, 582

(1 961). (33A) Misek, T., Czech Pat. 88,415 (1960); Chem. Eng. 68, No. 9.

58 (1961). (34A) Olney, R. B., A . I . Ch. E . Journal 7, 348 (1961). (35A) Planovskil, A. N., Bulatov, S. N., Khim. Mashinostroenip

1960, No. 2, p. IO; No. 3, p. 9. (36.4) RaginskiY, L. S., Shirskii, A. N., Khim. Prom. 1960, p. 414. (37A) Rao, G. J., Rao, C. V., J . Sci. Ind. Research (India) 200,

1961).

7, 46 (1961).

Zhur. Priklad. Khim. 34, 548 (1961).

ORNL-3018,1961.

(1961).

Can. J . Chem. Eng. 39, 189 (1961).

7, 463 (1960).

42, 17 (1960).

Academic Press, New York, 1961.

Pat. 2,955,932 (Oct. 11: 1960).

37 (1961).

39, 1 (1961).

V. N., Khim. Prom. 1959, p. 689.

1960, p. 496.

Mashinostroenie 1960, No. 2 , p. 13.

Khim. 33, 2344 (1960).

(1961).

101 (1961).

6 2 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y

(38A) Rao, M. R., Rao, C. V., J . Chem. Eng. Data 6, 200 (1961). (39A) Ryon, A. D., Daley, F. L., Lowrie, R. S., U. S. Atomic

(40A) Shinnar, R., J . Fluid Mcch. 10, Pt. 2, 259 (1961). (41A) Shirotsuka, T., Honda, N., Matsumoto, K., Kagaku Kogaku

(42A) Simard, R., Gilmore, A. J., McNamara, V. M., others,

(43A) Sitaramayya, T., Laddha, G. S., Chem. Eng. Sci. 13, 263

(44A) Sobotnik, R. H., Himmelblau, D. M., A . I. Ch. E. Journal

(45A) Sokolov, V. N., Reshanov, A. S., Zhur. Priklad. Khim. 34,

(46A) Thegze, V. B., Wall, R. J., Train, K. E., Olney, R. B.,

(47A) Treybal, R. E., IND. ENC. CHEM. 53,597 (1961). (48A) Vanderveen, J. H., U. S. Atomic Energy Comm. UCRL-

(49A) Winter, E. E., Russell, S. H. (to Atomic Energy of Canada,

(jOA) Woodward, T., Chem. Eng. Progr. 57, No. 1, 52 (1961).

Energy Comm. ORNL-2951,1960.

25, 109 (1961).

Can. J . Chem. Eng. 39, 229 (1961).

(1 961).

6, 619 (1960).

1047 (1961).

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8733,1960.

Ltd.), U. S. Pat. 2,990,254 (June 27, 1961).

Calculation Methods

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(5B) Lind, E. E., Goldin, J., Hickman, J. B., Chem. Eng. Progr.

(6B) Olander, D. R., IND. ENC. CHEM. 53, 1 (1961). (7B) Scriven, L. E., A . I. Ch. E . Journal 7, 524 (1961). (8B) Skelland, A. H. P., IND. ENG. CHEM. 53, 799 (1961). (9B) Trambouze, P., Chem. Eng. Sci. 14, 161 (1961). (10B) Trambouze, P. J., Piret, E. L., A . I . Ch. E. Journal 6, 574

(11B) Trambouze, P., Trambouze, M. T., and Piret, E. L.,

L. H., J . Am. Oil Chemists Soc. 37, 559 (1960).

56, No. 11, 62 (1960).

(1960).

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Experimental Fundamentals

(IC) Allen, K. A., McDowell, W. J., J . Phys. Chem. 64, 877

(2C) Bowman, C. W., Ward, D. M., Johnson, A. I., Trass, O.,

(3C) Bruckner, R., Naturwissenschaften 47, 371, 372 (1960).

(1960).

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(4C) Edwards, C. A., Himmelbiau, D. M., IND. EN& CHEM. 53, 229 (1961).

(5C) Elzinga, E. R., Banchero, J. T., A . I. Ch. E . Journal 7, 394

(6C) Elzinga, E. R., Banchero, J. T., Chem. Eng. Progr. Symp.

(7C) Fujinawa, K., Nakaike, Y., Kagaku Kogaku 25, 274 (1961). (8C) Garner, F. H., Tayeban, M., Anales real SOC. espafi. fis. y q u h .

(9C) Grassman, P., Reinhart, A., Chem.-Ing.-Tech. 33, 348 (1961). (1OC) Kafarov, V. V., Zhur. Przklad. Khzm. 34, 1061 (1961). (11C) Kintner, R. C., Horton, T. J., Graumann, R. E., Amberkar,

(12C) Kishinevskil, M. K., Mochalova, L. A., Zhur. Przklad.

(13C) McManamey, W. J., Cheni. Eng. Sci. 15, 210, 251 (1961). (14C) Maroudas, N. G., Sawistowski, H., Nature 188, 1186

(1960). (152) Massimilla, L., Volpicelli, G., Rzcerca sci. (Rome) 30, 2458

(1960). (162) Massimilla, L., Volpicelli, G., Masturzo, M., Rend. Soc.

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(18C) Quinn, J. A., Jeannin, P. G., Chem. *Eng. Sci. 15, 243, (1961).

(19C) Rao, M. R., Rao, C. V., J . Chem. Eng. D a h 6,209 (1961). (20C) Vignes, A., J. Chrm. phyr. 57, 980, 991, 999 (1960). (21C) Watts, H., Australian J . Chem. 14, 15 (1961).

(1961).

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(Madr id) 56B, 479, 491 (1961).

S . , Can. J . Chem. Eng. 39, 235 (1961).

Khzm. 33, 2049 (1960).

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