January 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
(50) (51) (52) (53)
Kennedy, C. C., Sewage Works J., 19,963-78 (1947). Key, T. D., J . Inst. CiviE Engrs. (London),29,323-34 (1948). King, W. W., Chem. Eng. Progress, 44, 717-20 (1948). Komline, T. R., Sewage Works J., 19, 806-10 (1947); U. S. Patent 2,426,886 (Sept. 2, 1947). Laufer, S., FoodInds., 20, 208-11, 326,328,378-81 (1948). Leathart, H. C., Chem. Eng., 54, No. 12, 139-40 (1947). Lee, J. A., Ibid., 55, No. 4, 119-21 (1948). Matheson, D. H., Water and Sewage, 85, No. 5, 85, 98, 100
(54) (55) (56) (57) (58) (59) (60)
Nance, E. L., Sewage Works Eng., 19,355-7 (1948). Ostenfeld, H. B., Sugar, 43, No. 7,24-5 (1948). Pickard, J. A., Food, 16, 313-14 (1947). Quigley, J. J., J.Biol. Chem., 172, 713-16 (1948). Rayburn, V. A., U. 9. Patent 2,440,487 (April 27, 1948). Robertson, R. H. S., Chern. Age (London),59, 347-50 (1948), Rosinski, L., Chirnie & industrie, 59, 17-21, 131-43 (1948).
(46) (47) (48) (49)
(1947).
41
(81) Rugeley, E. W., Feild, T. A., Jr., and Fremon, G. H., IND.ENQ. CHEM.,40, 1724-31 (1948). (62) Scheidt, W., Pharmazie, 2, 15-17 (1947). (63) Schroepfer, G. J., Sewage Works J.,19,559-79 (1947). (64) Stene, S., Anal. Chem., 19,937-8 (1947). (65) Sutcliffe, A., and Armitage, E., Pharm. J.,159,393 (1947). (66) Talbot, H, A,, Deco Trefoil, 12, No. 2, 5-12 (1948). (67) Thompson, ’R.E., Water and Sewage, 85, No. 9, 31, 57-8, 60 (1947). (68) Tyler, C., “Chemical Engineering Economics,” 3rd ed., pp. 97-9, New York, McGraw-Hill Book Co., 1948. (69) Vick, E. H., Surveyor, 105, 883-6 (1946). (70) Weitnauer, G., Schwek-Brau. Rundschau, 54, 19-27, 41 3 (1947). (71) Werstadt, K., Palha a voda, 27, 122-5 (1947). (72) Winkelmann, We-rkstatt u. Retrieb, 79, 196 (1946). RECEIVED
October 25, 1948.
FLOTATION B!J. BRUCE CLEMMER, BUREAU
OF
UNITEDSTATES MINES, TUCSON, ARE.
Y WAY of introduction, I should like to quote in part from a brief but explanatory editorial on flotation appearing in the March 1948 issue of Canadian Mining Journal: Any review of the progress that this particular branch of mineral dressing has made during the past quarter-century still brings a feeling of astonishment at the tremendous impact effected on the economic pattern of the mineral industry, in Canada no less than in other parts of the world. O m is on safe ground in averring that no other single metallurgical disc0ver.y of the past century has made available to the economic uses of man a greater quantity or variety of metals and diversified mineral products. Apart from quantitative considerations, the concentration and separation of minerals by flotation has had a profound, though indirect effect on the geographic distribution of ore deposit,s that could be exploited economically so that their metal or mincral content could be placed in the hands of man for his uses both peaceful and nefarious. The Aotation process has engaged the time and attention of a great many very able men in the establishing of the underlying principles involved and their application to practice, and new developments are constantly being made. The literature of the past year reveals that progress was made in applying the process t o a n increased variety of ores and nonmetallics and in explaining certain flotation reactions. Some of the more significant articles and patents will be detailed in this review, with only brief mention of others. This does not imply, however, that all are not important; together they serve as a basis for the more advanced studies and applications of the future. F U N D A M E N T A L AND THEORETICAL ASPECTS
The controversial subject of collector attachment t o mineral surfaces was discussed by Cook (14). H e contends that the present chemical and adsorption theories fail to explain the true mechanism of collection. He ascribes formation of collector coatings to adsorption of neutral heteropolar molecules. According t o this theory, for example, the flotation of galena by xanthates results from adsorption of neutral xanthic acid molecules rather than of xanthate anions. Similarly, free acid, free base, and neutral molecules are the effective entity for collection by long-chain paraffin acids, soaps, and salts. Although the theory aids explanation of several anomalies, many will question its validity. The application of radioactive tracers in flotation is being investigated in a n attempt to quantify the mechanisms of collection,
activation, depression, and frothing. Gaudin and co-workers (IS)described the equipment and procedure in use a t Massachusetts Institute of Technology, and several photographs of the apparatus were given in ( 1 ) . The study, sponsored by the Chemical Division of Armour & Company, Chicago, Ill., thus far has been confined to development of the technique for evaluating CI4-tagged n-dodecyl amine and lauric acid. Although more elaborate equipment is required, internal counting gave greater accuracy than window counters owing to relatively low energy (0.154 m.e.v.) and penetrating power of the emitted beta rays. The research on tagged reagents should go far toward explaining the mechanisms of flotation on a scientific basis. Spedden and Hannan (49)studied the contact and attachment of xanthate-coated galena particles on coursing free air bubbles A novel method was employed that embraced blowing air through a capillary tube into a glass flotation cell mounted on the stage of a microscope with a horizontal axis. The xanthate-conditioned particles were so introduced that the falling particles would meet the column of upward-rising bubbles in the field of view under 1SX magnification. A high-speed camera recorded the events at 3000 frames per second. They observed that a large proportion of particles making contact became attached t o the bubble surfaces; flow of fluid around the bubble surface influenced h e particles more bhan coarser sizes, but the flow did not prevent contact; the bubbles released from the submerged orifice were not spherical but exhibited an oscillating motion (changing shape) having a frequency of the order of 1000 per second. Several of the photographs given in the articles were subsequently reproduced ( 2 ) . REAGENTS
Several new reagents and novel reagent combinations for the flotation of sulfides and nonsulfides were reported. Bishop (6) patented the use of soluble salts of cymene sulfonic acid as frothing agents in the flotation of sulfides. Gibbs (24) used or-mercaptobutyric acid as the depressant in selective flotation of sulfides by conventional frothing and collecting agents. Moyer ($7) showed that sphalerite could be floated from chalcopyrite by using controlled quantities of lime and copper sulfate in conjunction with a dithiophosphate collector. Subsequent addition of lime and dithiophosphate permitted activation and flotation of the initially depressed chalcopyrite.
42
INDUSTRIAL AND ENGINEERING CHEMISTRY
American Cyanamid investigators continued their reseai ch on oil- and water-soluble petroleum sulfonates in flotation. Booth and Herkenhoff (9) patented use of the oil-soluble sulfonates in conjunction with monobasic carboxylic or aromatic sulfonic acids for the flotation of iron oxides from acidic (pH 2 to 6) pulps. In another patent ( I O ) , they used mixtures of oil- and watersoluble petroleum sulfonates for flotation of certain nonsulfides, including iron oxides, garnet, and phosphate rock, from pulps substantially free of slime. Booth and Carpenter (8) obtained a patent on flotation of several alkaline-earth metal-salt minerals by Rater-soluble sulfonates of the green-acid type. Examples of piactice included barite, calcite, celestite, phosphate rock, fluorite, schoelite, talc, and magnesite. Among the various collectors used successfully for flotation of sulfides, particularly from acidic pulps, are the carbonyl tetrathiodiphosphates resulting fiom reaction of diethyl or dibutyl dithiophosphates with carbonyl chloride. Fischer ($1) obtained a patent on the preparation of these compounds. A number of new organic compounds were patented during the year; these should find application in the flotation of sulfides and nonsulfides. I n additibn, new procedures were developed for preparing thiols, thiocarbanilide, and various amines and quaternary ammonium compounds previously found effective as eollectors. Novel reagent combinations developed for spccific types of ores will be discussed in the respective sections. RARE A N D PRECIOUS METALS
Flotation n a s succemfully applied to low-grade gold ores of thc CIipple Creek district t o recover a rougher concentrate for subsequent roasting and cyanidation treatment (d9). Auriferous pyrite and associated sulfotellurides were floated from the coarsely ground ores, using a mixture of sodium ethyl xanthate and American Cyanamid reagent 301 as the collector, with pine oil and methylamyl alcohol as frothers. The conventional subaeration, impeller-type cells were converted into rotor-stator cells to obtain the increased aeration and agitation necessary for making a low-grade tailing, assaying 0.01 ounce gold per ton or lower. The paper is one of several published during the year that stresses the influence of mechanical design of cells on metallurgical results. The flotation-gravity concentration of gold- and platinumbearing copper ores a t the plant of the Green Mountain Mining Company near Dixon, Mont., was described by Love (84). Covellite, the principal copper mineral, was floated with ethyl and pentasol xanthates from a pulp made just alkaline (pH 7 to 8) with lime. Gold, platinum, and silver follow the copper and are recovered. The milliiig of tin-silver ores from the Pirquitas mine on the Andean plateau of Argentina was described by Clayburg and Lancaster (12). The economic minerals are cassiterite and the silver-antimony sulfides pyrargyrite and miargyrite. The sulfides are recovered by flotation complimented by gravity concentration for recovery of the tin. The tin concentrate is retreated by flotation t o reject gangue sulfides. Mill results are good on the difficult ore. SULFIDE ORES
A number of papers published during the year reveal that progress was made in perfecting several new separations and in improving the efficiency of present plants by better reagent, control and by new combinations of old reagents. The more academic papers include a study by Plante and Sutherland (39) of the effect of oxidation of sulfide mineral surfaces on their flotative properties. Captive-bubble tests were made on polished sections of purified galena, pyrite, chalcopyrite, and sphalerite after being superficially oxidized by standing in aerated distilled water of knonn pH for several days. They report that oxidation of the sulfides produces soluble cations and sulfate in neutral or
Vol. 41, No. 1
acid pulps, and polgthionates, sulfates, sulfites, and thiosulfate in an alkaline pulp. Curves showing the relation between sodium cyanide concentration and p H for attachment of the captive bubbles to the pure and oxidized mineral surfaces are given. In general, oxidation increased tolerance of the minerals to cyanide and alkali when using ethyl xanthate for the collector. Plante (58) extended the study to other sulfides including antimonite, arsenopyrite, covellite, lollingite, marcastite, or piment, pyrrhotite, and tetrahedrite. Although the two papers are of interest in that they indicate the conditions favorable for bubble attachment to clean and oxidized surfaces, oxidation seldom aids and more often hinders an effective separation of two or more minerals. The use of sulfur dioxide for retarding galena in the flotation of chalcopyrite was mentioned in a previous review. Further details of the method was given in an article on milling practice of the San Francisco Mines, Sail Francisco del Oro, Chihuahua, Mexico (4). The procedure has superseded the so-called dichromate method in which sodium dichromate is used to retard galena during chalcopyrite flotation and the cyanide process in which the chalcopyrite is depressed and the galena floated. The sulfur dioxide from the sulfur burner is adsorbed in a scrubbing tower to give a sulfurous acid solution which is contacted Pith scrap iron to give a solution containing Some ferrous sulfite. Enough of the acid i s added to the bulk lead-copper concentrate t o give a pH of 3.0. After conditioning in a cascade box-type conditioner, lime is added t o raise the pH to 6.2 to 6.4 for flotation of the copper by an alcohol frother. Solubilized starch is used for pulp dispeision to assist retardation of fine galena; an excess retards some copper, and ethyl xanthate is needed t o reinstate flotation. Based on original feed, the reagent cost for the separation is less than 2 cents per ton of ore. Further information on the copper-lead separation \\as given by SlcQuiston ( 3 5 ) . He debcribed the flotation practice of the Idarado Mining Company, M here a combination of sodium cyanide and sodium sulfite provrd brttrr than dichromate or sulfurous acid-zinc hydrosulfite for separating lead and copper sulfide minerals from a bulk Concentrate. The sphaleiite in the ore is recovered in a separate concentrate The report also contains information on the influence of impellrr design and speed on metallurgical results. The practice of using highspeed rotor-type impellers for intense agitation and aeration in the roughing operations and slowspeed impellers in cleaning gives best metallurgical results. An interesting application of flotation for the separation of copper and nickel sulfides was patented by Sproule and co-workers (49). They disclose a process for separating a copper-nickel matte substantially free of iron; it comprises grinding the smelted mass to pass 100 mesh in a saturated solution of hydrated lime and in the presence of diphenyl guanidine u hich serves as the copper collector. The copper sulfides are floated from the retarded nickel sulfides. Success of the method is contingent on slow cooling of the matte to permit the crystals of the sulfides to grow to such a size that they can bc liberated on grinding. Bulk and selective flotation of Alaskan copper-nickel ores was described by East (18), and batch and laboratory pilot plant flotation of copper-cobalt sulfide ores was reported by Wells and co-workers (48). On ores relatively free of pyrite, selective flotation of chalcopyrite and cobaltite gave good results. On the pyritic ores, a combination of flotation and superficial oxidation methods was obligatory. The chalcopyrite wa5 floated bv xanthate and hfinerec 194 from a pulp made alkalinc with hydrated lime. The residual pulp was acidified, and the cobaltite and pyrite were floated in a bulk concentrate using Minerec A as the collector. The bulk concentrate was roasted a t about 350' C. t o superficially oxidize the pyrite, and the cobaltite was floated from the calcine. Other papers described the flotation of gold-antimony-tungsten ores a t Yellow Pine (3, I S ) , molybdenum-bismuth ores a t JJa
January 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
Corne (Y), and copper ores a t Mufulira ( W ) ,and Hayden (44).
(as), Roan
Antelope
OXIDIZED ORES
Despite wide variation in the deportment of oxidized ores toward flotation, progress is being made in developing economic treatment methods. These range from all-flotation for the simple ores t o rather elaborate leaching-precipitation-flotation procedures for the mixed and complex ores. Several papers on laboratory and plant flotation of oxidized lead, zinc, and copper ores were published. These included a general paper by Thom (47) describing the laboratory testing of lead and copper ores by conventional sulfidizing-flotation procedures. The soap flotation of lead carbonate was mentioned briefly. Bunge and co-workers (11) made use of soap flotation for concentrating zinc carbonate ores. A combination of citric acid and sodium silicate with caustic soda proved effective for retarding carbonaceous and siliceous gangue constituents during flotation of smithsonite. Fine (19) obtained favorable results on four oxidized lead ores by conventional sulfidizing and flotation procedures. Plant flotation of mixed oxide-sulfide ores at Darwin mines was described by Davis and Peterson (16). Successful treatment of the lead-silver ore required two-step flotation; the sulfides (galena, argentite, and sphalerite) were first floated, and the tailing was then sulfidized and refloated to recover the oxidized lead minerals, cerussite and anglesite. Ethyl and amyl xanthate were used as collectors. Stage addition of the sodium sulfide proved best. The composite concentrate contained 85% of the lead and 80% of the silver in the ore; the oxidized zinc minerals were not recovered. I n another article, Given (26) described the oxide practice at St. Anthony. As a t Darwin, stage addition of sodium sulfide proved best; a p H of 8.8 to 9.0 was optimum. American Cyanamid reagents 425, 301, and Aerofloat 31 were the preferred collectors for the sulfidized lead minerals; the oxidized zinc minerals were not recovered. The flotation of mixed sulfide-oxide copper ores at Nchanga was described by Talbot (46). The flow sheet embraced primary flotation of the sulfides t o recover a concentrate for smelting, and the tailing was refloated t o recover an oxide concentrate for acid leaching and electrolytic precipitation of the copper; the washed, leached residue containing some sulfides not recovered in the sulfide circuit was reground and returned to the primary sulfide circuit. METALLIC OXIDE ORES
Research in iron ore flotation continues active, but fewer papers and patents were issued as compared to last year. The use of petroleum sulfonates for floating oxides from a siliceous gangue has been mentioned (9, 10). DeVaney (17) chose another line of attack and patented the flotation of silica from iron oxides with long-chain aliphatic amines in an ammoniacal pulp. The flotation of various manganese ores was described in a series of reports by Schack, Poole, and co-workers (41). Anionic flotation of the manganese and cationic flotation of the silica were investigated. The deportment of the ores toward flotation differed materially depending on mineralogical association, degree of interlocking, softness of the ore constituents, and presence of soluble salts in the ores. All ores were not amenable, and many that responded favorably to flotation required careful reagent control t o obtain a concentrate acceptable for production of high-grade sinter. Milliken (36) presented an interesting paper on ilmenite flotation which sets forth some of the difficulties encountered in translating laboratory batch procedures into the large scale, continuous operation a t hTacIntyre. Present mill results attest that the difficulties were overcome; more than 85% of the ilmenite in the feed is recovered in a high-grade concentrate.
43
NONSULFIDE ORES
Kennedy and O’hleara (SO) gave additional information on flotation of beryllium ores. Tests were made on six berylbearing pegmatites and a helvite-danalite-bearing tactite. Good flotation of the beryllium minerals dcpended on prior cleaning of mineral surfaces by removal of alteration products. This was accomplished best by vigorously blunging the pulp with hydrofluoric acid, either added direct or formed in the pulp by interreaction of an inorganic fluoride and sulfuric acid. If the scrubbed pulp was still acid, washing t o give a substantially neutral pulp was necessary before flotation of the beryllium minerals with oleic acid. Tourmaline, if present, mas later floated from the cleaned concentrate by an aminc hydrochloride in an acid circuit. NONMETALLICS
One of the interesting recent applications of flotation for the separation of nonmetallics was proposed by Schoenlaub (40). He patented the separation of magnesium carbonate from calcium carbonate in dolomite; the process comprised calcining the dolomite, making a slurry of the material, introducing carbon dioxide t o the slurry t o form calcium carbonate and growing crystals of magnesium carbonate of separable size in the presence of an anionic collecting agcnt, such as sodium palmitate or sodium naphthenate. The slurry then was floated t o recover a magnesium carbonate concentrate and a calcium carbonate tailing. The quantity of phosphate rock recovered by flotation greatly exceeds the combined tonnage of all other nonmetallics so processed. Froth flotation of the fines and agglomerate-tabling (a flowing-film concentration process in which shaking tables are used as the separating device) of the coarser sizes is conventional practice in modern phosphate concentrators. The Homeland plant ( S I ) of the Virginia-Carolina Chemical Corporation and the Noralyn plant (33) of International Minerals and Chemical Company were recently described in detail by Lenhart. These new plants, with a combined capacity of more than 2.5 million tons of finished concentrates and pebble phosphate per year, are a far cry from the small inefficient phosphate washers of earlier years. The past 10 years have witnessed widespread commercial ndaption of flotation for separating fluorspar from calcite, silica, and other associated gangue minerals in low-grade ores. Except for a small tonnage of hand-picked lump, all of the acid-grade fluorspar and much of the ceramic fluorspar produced in this country are from flotation of gravity-plant fines and low-grade, disseminated ore. The flotation and gravity-concentration practice of Colorado Fluorspar Mines, Inc., was described by Lintner (38). Jigging of the coarse feed, complemented by flotation of the fines, yields metallurgical and ceramic grade concentrates. The Bureau of Mines reported the results of batch flotation tests on a number of low-grade and disseminated ores from the Illinois-Kentucky district and several western deposits (6). Other publications on the flotation of nonmetallics included a discussion of barite milling methods t o prepare a weighting material for oil-well drilling mud (38), the laboratory flotation of barite ores (30) and phosphate rock (16), and the purification of glass sand by multiple-step flotation with anionic and cationic collectors to reduce ferruginous impurities (46). COAL
Simultaneous reclaiming and dewatering of fine coal in washery waters by flotation were described by Gandrud and Riley (82). A novel four-cell flotation machine was employed. The conventional froth paddles were replaced with a flight conveyer of perforated scrapers for removal and initial dewatering of the floated coal. The froth product was mechanically squeezed in a
INDUSTRIAL AND ENGINEERING CHEMISTRY
44
dewatering auger having wedge-wire sections in the trough; the effluent was returned to the machine. The flotation and dewatering practice at the Tamaqua Colliery was described by Gisler
(++!a.
EQUIPMENT AND CONTROLS
The Kovember 1947 issue of Engineering and M m i n g Journal &asdevoted t o modern methods and equipment being uaed in the mineral industry for exploration, mining, milling, and metallurgical processing. Numerous photographs of the automatic controls in use a t Tennessee Copper Company London and Isabella mills were included. The flow sheets of the plants are complex and involve bulk flotation, then separation of magnetic iron, pyrite, copper, and zinc concentrates. Complemented by automatic controls, one operator can run the plant; a helper tends reagents and samples. No review 1% ould be complete without reference to the aiinual b'lotalion Index published by The Doiv Chemical Company. The index contains a bibliography of foreign and domestic articles and patents compiled from more than thirty source:s. LITERATURE CITED
Anon., Eny. hfini7egJ., 149, No. ?, 5 8 - 5 (1948). Ailon., Ibid., No. 7, 95-7.
Anon., Mir/,iny World, 9, Nu. 12, 26-31 (1947). Anon., Ibid., 10, No. 6, 16-18 (1948). Ratty, J. V., et al., U . S. Bur. M i n e s , Repts. Invest. 4133; 4139 (November 1947) ; 4143; 4158 (December 1947). Bishop, W.T., U. S. Patent 2,446,207 (Aug. 3, 1948). Bonham, W.M., Can. Mining J., 68, 881-4 (1947). Booth, R. B., and Carpenter. J. E., U. S. Patent 2,442,455 (June 1, 1948). Booth, R. B., and Herkenhoff, E. C., f h i d . , 2,439,200 (Apr. 6, 1948).
Ibid.,2,433,258 (Dee. 23, 1947). Bunge, F. H., Fine, M. M., and Legsdin, A , , Univ. Missouri School M i n e s und M e t . , Bull., Tech. Ser., 17, No. 3 (1947). Clayburg, G. A., and Lancaster, H. K., Deco Trefoil Bull. M4-B48 (February 1948). Cole, J. 'CV., and Bailey, H. D., U . S. Bur. Mines, Inform. Circ. 7443 (April 1948). Cook, M. A . , paper presented at Am. Inst. Mining Met. Engrs., Regional Meeting, El Paso, Tex. (October 1948). Davenport, J. E., and Haseman, J. F., Am. Inst. Mining M e t . Engrs., Tech. Pub. 2239 (November 1947).
Vol. 41, No. 1
(16) Davis, D. L., and Petemon, E. C., Ibid., 2407 (July 1948). (17) DeVaney, F. D., U. S.Patent 2,450,720 (Oct. 6, 1948). (18) East, J. H., Trover, W. h l . , Jr., Sanford, R. S., and Wright, W. i. , U . S . Bur. hfines, Repts. Invest. 4182 (January 1948). (19) Fine, M. M., Ibid., 4301 (June 1948). (20) Fine, M. M., and Kennedy, J. S., Ibid., 4280 (May 1948). (21) Fischer, A. €U. I. S. ,Patent 2,434,367 (Jan. 13, 1948). (22) Gandrud, B. W., and Riley, H. L., 6'. S , Bur. Mines, Repts. Invest. 4306 (July 1948). (23) Gaudin, A. AI., de Bruyn, P. R ,Bloecher, F. W.,and Chang, C . S., Mining and ;lfet., 29, 432-5 (1948). (24) Gibbs, H. L., Us S.Patent 2,449,984 (Sept. 28, 1948). (25) Gisler, H. J., Deco Trefoil'BuZl. M4-B50 (October 1948). (26) Given, E. V., Eng. Mining J., 149, To. 4, 88-90 (1948). (27) Goldrick, hI. R., Am. Inst. -1fining M e t . Engrs., Tech. Pub. 2251 (January 1948). (28) Harding, A. C . , I b i d , 2414 (July 1948). (29) Keil, 13.R., i b i d . , 2361 (May 1948). (30) Kennedy, J. S.,and O'Meara, R. G., U . 9. Bur. Mines, Repts. I n u e s t . 4166 (Januarv 1948). (31) Lenhart, W. B., Rock hwh&, 51, No. 4, 104-10 (1948). (32) I b i d . , SO.6 116-21. (33) Lintncr, R. E., Deco 2'refo;Z Bull. M4-B47 (December 1947). (34) Love, W. H., Mining World, 10, No. 8 , 24-6 (1948). (35) McQuiston, E W.,Jr Am. Inst. .Minino M e t . Enars., Ted&. Pub. 2349 (May 1948). (36) Milliken, F. R., Ibid., 2355 (May 1948). (37) Moyer, S.P., U. S.Patent 2,430,778 (Nov. 11, 1947). (38) Plante, E. C., Am. Inst. ,Tfining J.f?,lpt. Engrs., Tech. Pub. 2298 (January 1948). (39) Plante. E. C., and Sutheiland, K. L., I b i d . , 2297 (January 1948). (40) Schoenlaub,R. A., U. S. Patent 2,433,297 (Dec. 23.1947). (41) Shack, C. H., Poole, 11. G., et aZ., U . 8. Bur. ;Mines, Repts. Invest. 4111, 4137, 4140, 4141, 4142, 4147, 4148, 4149, 4186, 4291, 4302 (November 1947 t o June 1948). (42) Spedden, H. R., and Hannan, W. S., Jr., Ana. Inst. Mining M e t . Engrs., Tech. Pub. 2354 (March 1948). (43) Sproule, W. K., Harcourt, G. A,, and Rose, E. H., U. S. Patent 2,432,456 (Dec. 9, 1947). (44) Stevens, J. L., paper piesented at meeting of Ole Dressing Division, AIiaona Section, Am. Inst. Mining hIet. Engrs., Hayden, Aria. (December 1947). (45) Stokes, E. B., U. S Patent 2,433,633 (Dee. 30, 1947). (46) Talbot, H. A , , Deco TrefoiZBuZZ. M4-B49 (June 1948). (47) Thorn, C., Ibid.,T4-B8 (August 1948). (48) Wells, H. R., Sandell, 1%'. G., Snedden, H. D., and Mitchell, T.F., U . 8. Bur. Mines, Repts. Invest. 4279 (May 1948). (49) White, Jack, and Adair, R. B., Am. Inst. Mining M e t . Engrs., Tech. Pub. 2250 (January 1948). ~
~ ? E C E I V E D October
26, 1948.
5 DONALD F. BOUCHER, ENGINEERING DEPARTMENT, E. I. DU PONT DE NEMOURS & COMPANY, INC., WILMINGTON, DEL.
HERE has been a substantial increase during the past' year in the number of published articles appearing on subjects related t'o fluid dynamics. Considerable attention has been given to fundamental aspects of fluid mechanics such as turbulence, boundary layers, shock Tvaves, etc. There were fewer articles on fluidized solids this year, although the behavior of the fluid bed is beginning t o rcceive some more jerious study. Solids in flow behave differently from fluids and this is receiving more attention each year. A large number of articles were concerned with flow around objects, alt,hough the majority of these are of interest mainly in the field of aeronautics. X large amount of data wa,s reported this year on flow t'hrough beds of solids and some new correlations were offered. In the field of pumping machinery, the development of the axial-flow compressor is proceeding at a fast pace. In connection with fluid metering, the
hot-wire anemometer is receiving wider use and is appearing in many modified forms. The properties of non-Newtonian fluids have once more been the subject of considerable study. FUNDAMENTALS
General. h large number of references and books have appeared during the past year covering Ihe fundamental and theoretical aspects of fluid dynamics. The majority of these pertain to aerodynamics, and are so advanced as to be of little interest to the average reader-that is, the average chemist or chemical engineer. Only a limited coverage of them is given here. For a more complete coverage, see the new journaI of the American Society of Mechanical Engineers, Applied Mechanics Reviews; thc first issue appeared in January 1948. T3unsaker and Rightmire (125) offer a new book on engineering
