Size
Reduction
of innovations and reports of progBesides ress, ' athisnumber . year saw major conferences and conference proceedings in size reduction and in fracture mechanics and the debut of a newjournal, Powdn Technology (Elsevier). Conferences
The customary flood of new equipment in the literature is accompanied by more fundamental studies of solid fracture and by kinetic modeling of grinding processes
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The Second European Symposium on Size Reduction was held at Amsterdam in September 1966. The proceedings have already been published, no mean achievement of the editors, Rumpf and Pietsch (58). Detailed summaries and commentaries of the papers are being published in Powdm Tcchnology and these should be especially helpful for those papers which were originally in a foreign language. A few of the more important papers are discussed at appropriate points in this review. The Engineering Foundation Research Conferences on Particulate Systems held August 1966 and 1967 in Milwaukee attracted a galaxy of leading workers from all over the world. As with the Gordon Conferences, the opportunities for discussion were even more valuable than the original papers.
RICHARD H. SNOW LINCOLN T. WORK
ANNUAL REVIEW
An international conference on particle size analysis was held at Loughborough, England, September 1966. Kaye (28) gives a report of the conference. The 28 papers offer “an exciting mixture of academic abstraction, commercial optimism, and pragmatic reality.” T h e first International Conference on Fracture was held in Japan in 1965. The proceedings consist of five parts as follows : Mathematical, Physical and Continuum Mechanical Theories; Atomistic, Microstructural and Macroscopic Mechanics; Strength and Fracture of Non-Metallic Materials ; Fatigue and Fracture with Emphasis on Macroscopic Behavior; Environmental Effects, High Pressure, High Temperature, High Strain Rate, and Radiation Damage. This conference contains papers which pertain to three areas of possible interest to workers in the field of comminution. These three areas are : (1) Markings and topography of fracture surfaces ( 2 ) Effect of temperature on strength of brittle materials (3) Actual data from fracture experiments on various materials
I n “The Analysis of Fracture Surfaces by Electron Microscopy” by R . M. N. Pelloux and J. C. McMillan, a review is made of the characteristic topographics and features of different fracture surfaces resulting from tests where the fracture conditions were known. Similar observations are presented in “Fracture Mechanisms and Fracture Surface Topography’’ by H. C. Burghard and D. L. Davidson, who studied plastic fracture, cleavage, and fatigue crack propagation. The second area of the thermal dependence of strength is investigated, in part, in “Structural and Theoretical Strength of Glass” by G. K. Demisher and G. M . Bartenev. By considering the effect of the microstructure on strength, they were able to predict the value and temperature dependence of the theoretical strength of glass. The method is based on an analysis of the curve of thermal linear expansion and the temperature dependence of sound velocity. Calculations were made for alkali silicate sheet glass, arid from the comparison of the
LINCOLN T. WORK has written the Size Reduction review in I&EC every year, with the single exception of 1964, since its inception in 1947. N e x t g e a r , however, he will hand the review over to Richard H. Snow, his collaborator in 1966 and 1967. Over theyears D r . Work has covered the transition of the subject f r o m Crushing and Grinding-its original title-to Size Reduction, and has reported the increasing relevance of particle size measurement, classijcation and size enlargement. Though pleased with the trend away f r o m empiricism in mill dpsign, he still feels that there is a need f o r understanding of fracture and energy considerations. I@EC is grateful to Dr. Workf o r these 2Oyears oJ cffort, in which he has presented f o r readers the essential advances in size reduction.
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Fracture behavior is generally considered to be related to the distribution of flaws calculated and experimental results it follow-s that the temperature dependences of both theoretical and real strengths are in agreement. The third area of interest, that of actual data from fracture experiments on several materials is represented by papers such as: “Fracture of Amorphous Polymers” by R. F. Landel and R . F. Fedors; “Crack Velocity in Plastics” by K. Saito and H. Mishina; “Fracture Studies in Polypropylene” by K. D. Pae, D. R . Morrow, and J. A. Sauer; “Strain-Rate-Dependent Breaking Strength of Polymethyl Methacrylate” by M . Higuchi ; “Fracture of Ceramics” by V. TYeiss, R. Chait, and J. G. Sessler; “Plastic Flow and Crack Nucleation in Magnesium Oxide” by A. Briggs and F. J. P. Clarke; “Static and Fatigue Fractures of Portland Cement Mortar in Flexure” by J. Glucklich. Fracture Behavior
A review of the fracture of brittle materials by Pugh (50) presents clearly this subject, of which those interested in size reduction should have some knowledge. Pugh discusses theories of crack growth according to continuum, atomistic, and energy theories. He discusses models for crack nucleation, such as pile-up of atomic dislocations. Flaws which are not sufficient to nucleate a crack can be aided by fatigue phenomena such as slip until they are suficient. But cracks can be stopped by inclusions and grain boundaries, so that heterogeneous materials can be stronger than their components. This mechanism of dispersion-strengthening a glass matrix is also discussed by Hasselman and Fulrath (20). Fracture behavior is generally considered to be related to the distribution of flaws in the sample. Conversely Greene (77) derives equations to deduce the flaw distribution from strength data for glass rods and laths. He also considers limitations of the statistical theory of distribution of flaw strength. After considering the conditions under which a particle will break, we turn to considerations of the breaking process itself. Three papers analyze the stresses that occur in specific shapes, especially spheres, under single particle breakage conditions. Rurnpf et al. (57)present high speed spark cinematographs which clearly show the growth of bundles of cracks in small glass spheres breaking under compression. They then consider the classical analysis of stress near the contact point according to Hertz, and attempt to extend this analysis a short distance into the sphere to see how the stress might influence the crack propagation. Actually, they carry the analysis beyond its range of validity, pointing out that no other approach is available. Habib et al. (79) show the form of 82
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
breakage cracks in disks and spheres of rock and attempt to interpret the results in terms of the theory of stress distribution of Sternberg and Rosenthal (64,which is applicable everywhere except near the contact points. It becomes clear that directly under the contact zone, there is a region where neither theory is valid, and where each gives different results. The complex equations of Sternberg and Rosenthal for the stress at a point in the sphere are put in convenient explicit form by Hiramatsu and Oka (22). Milling Simulation
A series of papers in the Second European Symposium of Size Reduction concerns simulation of the ball milling process treated in terms of kinetics, in analogy with chemical reaction kinetics. Patat (47) summarizes the work done at his school over a number of years, in which the conditions leading to various orders of kinetics are clearly brought out by suitable experiments. Mika et al. (38) solve the equations of grinding in ball mills for first-order kinetics and discuss the difficulties in obtaining an adequate fit to experimental data with this assumption. Austin et al. ( 3 ) present their finite difference method of solution of the equations of grinding and discuss its relation to other methods. They describe their computer program which includes a method of fitting a selection function based on the first-order assumption to experimental data. They conclude tha; the first-order assumption is not really adequate. Just as in the field of chemical kinetics, there is a tendency to oversimplify the concept of reaction order. Schonert (62) presents model calculations for a simpler type of mill on a sounder basis. He considers an idealized impact mill provided with a sieve in closed circuit. He then applies his own size distributions from breakage of single limestone particles and determines the effect of sieve sizes, number of breakage steps, and loading intensity on the performance of the system. Kelsall (30) describes experiments on the kinetics of milling in a sinal1 continuous wet ball mill. In this method, the feed is suddenly switched from calcite to quartz, and the mill behavior is analyzed from the point of view of the step change in feed. The rate of quartz milling is first order,
Richard H . Snow is a Senior Engineer, Chemical Engineering Research, I I T Research Institute, Chicago, Ill. Lincoln T . W o r k is a Consulting Chemical Engineer, iL’ew York City. T h e authors thank Dr. B. W . P a d d i n g for contributing the review of the International Conference on Fracture. AUTHORS
but of course it is in an unusual environment. Miwa (39) applies concepts of kinetics of milling to the Bond grindability test method. T h e total number of mill revolutions, usually adjusted by trial and error, may be predicted with an equation given. Performance of Mills
Turning to crushers, Brown (8) analyzes processes that could account for the energy required in free crushing and concludes that friction between fragments accounts for a considerable portion of the energy supplied and is likely to be the major reason for the low efficiency of pulverizers. Ohe (45) studies single particle breakage of limestone and cement clinker in a roll mill, giving special attention to the attrition due to differential roll speed. Attrition reduces energy efficiency, except for high reduction ratios for small feed particles. I n the latter case the improvement is due to more effective disintegration of compacted agglomerates. Adamski ( I ) gives further data on application of his IBJ mill which features acceleration of the feed particles before they enter the nip. Leschonski (34) studies the performance of a new type of cylindrical mill with an annular grinding aperture and an axial flow of air superimposing the gravitational flow of material. The experimental results can be explained and reproduced by a simple load model. Kurten and Rumpf (32) describe jet milling triboluminescent material, Such a material gives off light when it fractures, thus revealing the location of breakage events. Design of the mill can be varied to find optimum conditions. Two articles discuss slurry grinding. Turner and McCarthy (77) mathematically analyze mechanisms operating in Kady, colloid, and pigment roll mills, where soft particles are ruptured by fluid shear. The results check experiment and appear to give a good understanding of the behavior of such mills. Krekel (37) studies comminution of agglomerates by shear in roller mills and masticators and experimentally checks the load a t which particles yield. There is continued interest in vibratory mills. Papacharalambous (46) points out practical advantages of vibratory milling of hard materials such as silicon carbide, alumina, and boron carbide. Ju-Chung et al. (26) report a study on the impact period of the grinding media. They discuss application of the results to the optimum design and operation. Zagury (76) proposes a new type of vibratory mill using rods instead of balls and called “Vibrotub.” I t is said to be more efficient than a conventional rod mill. Planiol (49) advocates comminution of particles by projecting them against hard targets in vacuum. Important economy of energy, increasing rapidly with desired fineness, is claimed. The idea that future crushers may use totally different forces is advanced again in the Engineering &3 M i n i n g Journal (72). Zorll and Klinke (77) follow the grinding of T i 0 2 pigment by measuring the change in dielectric constant and dielectric loss.
Applications
A large number of articles discuss the application of mills to various industrial tasks. Nijman (42) reviews applications of ball and pebble mills for which they are preeminently suited despite other new competing mills. Matsui (37) presents a ball mill design relation. An article in Glas-Email-Keramo- Technik (15) describes the transition from edge-runner mill to a modern German roller mill in the ceramics industry. This mill is said to be more efficient than a ball mill, and more versatile. Another mill used in the ceramics industry is a spring loaded cone crusher, a descendent of the Symons crusher. Operating data are given by Mulisch (40). Bitzer ( 6 ) describes a new U. s. high speed Gyradisc crusher, which is said to extend the range of dry crushing to lower sizes of product, while retaining the low unit operating costs of the cone crusher. Lauer (33) reviews the state of the art of crushing in fine impact breakers. Beke (5) discusses cement grinding problems, especially the hardening characteristics of cement as a function of particle size and its distribution. Locher et al. (36) present experiments investigating the same subject. Deurbrouck and Palowitch ( 1 1) review available data on the effect of crushing high sulfur Appalachian coal and conclude that significant sulfur reductions can be obtained when certain coals are crushed to below 14 mesh. Griffiths (78) discusses the manual control of grinding of glazes and vitreous enamels, with emphasis on practical problems of usage of mills and equipment. Murdock (41) discusses use of telemetry instruments to fix variables, as well as design problems related to starting synchronous motors for mills. Gavelin (14) studies the effect of variables in producing groundwood for paper manufacture. Rauner et al. (51) develop a process to ball-mill brittle materials in such a way as to produce a free flowing product, thus preventing agglomeration during milling. Silica aerogel powder, 0.01 to 0.2 part, is first treated with 0.001 to 0.004 part of hexamethyldisilazane in 0.5 to 2 parts of an inert fluid in the mill. Then one part of the material to be milled is added and ground. After the solvent is vaporized off, the silica coats the particles and acts as a flow promoter. T h e disilazane does not act as a lubricant as in other studies of silicone additives, but is chosen for its ability to react with water adsorbed on the solids to reduce surface energy. Experimental data are given for milling of sodium chloride and other materials.
Autogenous Milling
A number of ore processing installations of autogenous milling are described. Dettmer and Sobering (10) describe an Aerofall mill flowsheet processing iron ore in Labrador. The mine faces are mapped according to grindability and iron recovery to permit feeding a mixture for best results. Javelle et al. (25)describe a French operation of a Cascade mill on low grade limestone-iron ores. Such wet autogenous grinding is said to produce a higher percentage of fines than rod and ball mills with VOL.
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less energy. By controlling the proportion of solids, production of fines smaller than 1 p is controlled. Jackson (24) describes Aerofall milling of gold ore in South Africa and gives data on the economics of adding some steel balls. Telepnev (68) describes economies resulting from autogenous grinding after a first stage of conventional gold ore ball milling in Russia. Yashin and Vaisberg (74) report the autogenous wet milling of tin ore in Russia. Energy requirement is less than with conventional ball mills, slime formation is considerably diminished, and loss of tin in untreatable slimes is reduced
2.5%. Particle Behavior
Ridgway and Tarbuck (53) review knowledge concerning the random packing of spheres. Rumpf et al. (56) investigate the. geometrical properties of cut through granular column packings and relate observed properties of the section t o the size distribution for spherical and irregular bodies. They suggest a method of testing and describing the structure of the packing. Goldsmith (76)similarly calculates true particle size distributions from the sizes observed in a thin slice. Lewis and Goldman (35) propose theorems for calculating weight ratios to produce maximum packing density of powder mixtures, a very important property for brick manufacture. The flow of powden and granular solids is studied by Pilpel (48) who reviews the problem of designing bins to give reliable discharge of material. Athey et al. (2) show evidence of slip boundaries in hopper discharge by means of x-ray pictures. Bowden and Tabor (7) review the progress that has been made during the last decade in the processes involved in friction, lubrication, and wear. Wiegand and Heinke (73) discuss fundamental aspects of mechanical wear of metals, considering adhesive wear and scratch abrasion most important. The effect of relative hardness of the two materials differs according to the type of wear, but an example shows that hardness alone is not determining. Fahlstrom and Andren (73)state that wear in Cascade (wet autogenous) mills is 15% of that in rod mills, and is lower in large diameter, slow speed mills than in the converse. Norman (43) reports new applications for Climax Molybdenum's latest austenitic alloy in mill parts subject to impact. Salkind and Lemkey (60) report that a composite containing whisker crystals can be grown if certain eutectic alloys are frozen from the melt in one direction. If this could be done with steel, the result would be a material of high impact strength suitable for crusher parts. There are several articles on the mixing of dry powders. Sugimoto et al. (65) describe the time variation in output of granular mixtures flowing through a rotating cylinder, with application to ball mills. Toyama (70) presents studies on a table feeder. Vance (72) clarifies the statistical terms used in predicting the performance of dry blenders and develops a simple statistical procedure to indicate good dry mixing. Hyun and Marc De Chazal (23) present a statistical definition of perfect mix84
INDUSTRIAL AND ENGINEERING CHEMISTRY
.
Figure 1. Sprout- Waldron Gyro- Whip Sifter showing path of Jnes and oversize
-4
t-3 6
Fzpm 2. Multi-Plcx Laboratory Zigzag Class@? 100 M Z R 7. Drive shaft 4. Clmifving rotor 2. Fced rating worm 5. Clnrrifyins air 2. Feed rnatninl 6. Coom product 7 . Finr product
tures of solids of different sizes. Closed form results are given for a mixture of three sizes. Classifiers
I n one of a few articles on classifiers, Richards (52) discusses the efficiency of classifiers and the parameters necessary to characterize classifier efficiency and suggests that earlier representations of efficiency are inadequate. Scholz et al. (67) describe an elutriation particle separator. Rose and Schreckengost (55) discuss the advantage of screens made with wires of special cross section. Sharp corners reduce blinding and aid water take-off. Sahu (59) gives results showing the effect on roundness of grains on sieving characteristics. Robertson and Engel (54)study the effectiveness of sieving with a cycling air jet directed up under the sieve. The capacity and speed are better than with a Ro-tap, and there is less tendency to bind. Motion pictures show that agitation and bounce against the screen are determining factors, not preferential flow of fines. The principle seems similar to the Alpine jet sieve and the Allen-Bradley Sonic Sifter described in last year’s review. Two new laboratory or pilot-scale classifiers have appeared. One is the Sprout-Waldron Gyro-Whip Sifter, shown in Figure 1. This sifter features a nest of sieves with product overflow and downcomer passages, permitting combinations of sieves of various meshes to be arranged in parallel or in series. The turnover of material in going from sieve to sieve is said to aid separation. Alpine has produced its Zigzag Classifier in a laboratory model. The action of gravity used in previous models has been replaced by that of centrifugal force. This is done by passing the feed inwardly through a rotor on which are built the zigzag passages. A diagram is shown in Figure 2.
(7) Bowden, F. P.,Tabor,D., B r i t . J . Appl.Phy1. 17 (12), 1521 (1966). (8) Brown, R. W., Inst. Min. Met. Trans. 7 5 (715), (2173 (1966). (9) Burt, M . W. G., Kaye, B. H., Analysf 91 (1086), 547 (1966). (IO) Dettmer, P. B., Sobering, A., 7th International Mineral Processing Congress, Tech. Papers, New York, 1964,573 (publ. 1965). (11) Deurbrouck, A. W., Palowitch, E. R., U. S. Bur. Mines Inform. Circ. 8282, 37 pp.. 1966. (12) Eng. Min. J . 167 (6), 463 (1966). (1 3) Fahlstrom, P. H., Andren, T., 7th International Mineral Processing Congress, Tech. Papers, New York, 1964, 515 (publ. 1965). (14) Gavelin, G., Paper Trade J. 150 (Zj, 52-9 (1966). (15) Glas-Email-Keramo-Tech. 17 (3), 90 (1966). (16) Goldsmith, P. L., Brit. J. Appl. Phys. 18 (6), 813 (1967). (17) Greene, C. H., Gloss Tech. 7 (2), 54 (1966). (18) Griffiths, R . , Brit. Ceram. Soc. J. 3 ( I ) , 51 (1966). (19) Habib, P., Radenkovic, D., Salencon, J., Second European Symposium on Comminution, Paper A4, 1967. (20) Hasselman, D. P. H., Fulrath, R . M., J. Am. Cerom. SOC.49 (2), 68 (1966). (21) H i A. L. AEC Accession No. 11270, Rept. No. LA-3424, Available Dcpt. mn, &%TI, Z? pp., 1965. (22) Hiramatsu, Y., Oka, Y . ,Znt. J. Rock Mech. Min. Sci. 3 89 (1966). (23) Hyun, K . S Marc D e Chazal, L. E., INo. END. CHEM.PROCESSDEsraN DEVELOP. 5 (2),”105 (1966). (24) Jackson, 0. A. E., 7th International Mineral Processing Congress, Tech. Papers, New York, 1964, 557 (1965). (25) Javelle, P., Fulchiron, J., Guyot, R., 7th International Mineral Processing Congress, Tech. Papers, New York, 1964, 595 (publ. 1965). (26) Ju-Chung, C., Hui-chung, H., Chao, W., Kuei Suan Yen Hsuch Pao 4 (3), 129 (1965). (27) Kaye, B. H., Powder Tech. 1 ( I ) , 11 (1967). (28) Zbid., (2)’ 116 (1967). (29) Kaye, B. H., Tfeasure, C. R . G., Brit. Chem. Eng. 11 (lo), 1220 (1966). (30) Kelsall, D. F., Can. Min. J. 86 (IO), 89 (1965). (31) Krekel, J., Chem. I g . Tech. 38 (3), 229 (1966). (32) Kurten, H., Rumpf, H., Zbid., 38 ( I I ) , 1187 (1966). (33) Lauer, O., Chem. Technik 19 (11, 1 (1967). (34) Leschonski, K., Chem. Ing. Tech. 3 8 (7), 705 (1966). (35) Lewis, H. D., Goldman, A., J. Am. Ceram. Soc. 49 (6), 323 (1966). (36) Locher, F. W., Wuhrer, J., Schweden, K., Tonind. Z f g . Kcrom. Rundschau 9 0 (121, 547 (1966). (37) Matsui, Kunio, Kagaku Kogaku (Engl. ed.) 4 (Z), 295 (1966). (38) Mika, T. S Berlioz, L., Fuerstenau, D. W., Second European Symposium on Size Reducijon, Paper B2, 1967. (39) Miwa, Shigeo, Kagaku Kogaku 29 (21, 113 (1965). (40) Mulisch, E., Keram. Z . 18 (4), 230 (1966). (41) Murdock, V. G., Eng. Min. J. 167 (5), 86 (1966). (42) Nijman, J., Brit. Chm. Eng. 11 (3), 177 (1966). (43) Norman, T. E., Eng. Min. J . 166 (51, 86 (1965). (44) Oce ek, D., Eberl, E., Rudarsko -Met. Zbornik (4), 385 (1963); Engl. transl. in Min. Quart. (4),49 (1963). (45) Ohe, W.-von der, Chem. Zng. Tech. 39 (5, 6), 357 (1967). (46) Papacharalambous, H . G., Cerom. Age 82 (2), 32 (1966). (47) Patat, F., Second European Symposium on Comminution, Paper BI, 196’7 (48) Pilpel, N., Brit. Chem. Eng. 11 (7), 699 (1966). (49) Planiol, R., Metallurgie 5 (61, 239 (1964--65). (50) Pugh, S . F., Brit. J. Appl. Phys. 18 (2), 129 (1967).
dt.
Particle Size Analysis
Every year numerous articles describe and compare alternative techniques and apparatus for particle size analysis. Those by Simecek (63), Hipp ( Z ? ) , and Burt and Kaye ( 9 ) may be mentioned. Barnes et al. ( 4 ) compare the performance of the Coulter counter with other methods. Results with the same instrument show excellent reproducibility, but reproducibility from different Coulter instruments is questionable. An automatic recording size analyzer for respirable dusts is described by Talbot (66). A vacuum metallizing technique is used to obtain a projected image whose diffraction spectrum is analyzed. An automatic permeameter for control of cement particle size is described by Temiik and Vitovsky (69). The reliability and accuracy of alternative designs of permeameters are studied by Kaye (27). Kaye and Treasure (29) give charts for converting particle size data from a number to a mass distribution. REFERENCES (1) Adamski, T . , Euro-Cerom. 16 (IO), 176 (1966). (2) Athey, J. D., Cutress, J. O., Pulfer, R . F . , Chem. Eng. Sci. 2 1 (9), 835 (1966). (3) Austin, L. G., Klimpel, R. R., Beattie, A. M., Second European Symposium on Comminution, Paper B4 (1967). (4) Barnes, M . , Parker, M. S . , Bradley, T. J., Mjg. Chemist 37 (I 1, 47 (1966). (5) Beke, B., Epitoanyag 17 ( l ) , 7-11 (1965). (6) Bitzer, E. C., Eng. Min. J. 166 (3), 93 (1965).
(52) Richards, J. C., Brif. Coal Util. Res. Asroc. Monthly Bull. 30 (4), (I), 113 (1966). (53) Ridgway, K.,Tarbuck, K . J., Brit. Chem. Eng. 12 (3), 384 (1967). DESIGNDEVELOP. (54) Robertson, D. C., Engel, A. J., IND. ENQ. CHEM.PROCESS 6, ( l ) , 2 (1967). (55) Rose, C. G., Schreckengost, E. D., Mining Congr. J.5 3 (41,100 (1967). (56) Rumpf, H., Debbas, S., SchBnert, K., Chem. Zng. Tech. 39 (3), 116 (1967). (57) Rumpf, H., Faulhaber, F., SchBnert, K., Umhauer, H., Second European Symposium on Comminution, Paper A3, 1967. (58) Rumpf, Hans, Pietsch, W., eds., Proceedings of Second European Symposium on Comminution held a t Amsterdam, September 1966, Dechema Monograph. 5 7 , Frankfurt (1967). (59) Sahu, K., J. Sediment. Petrol. 35 (3), 763 (1965). (60) Salkind, M . , Lemkey, F., Znt. Sci. Tech. (3), 52 (1967). (61) Scholz, J.T., e t a l . , Rev. Sci. Znstr. 36, 1813 (1965). (62) SchBnert, K., Second European Symposium on Comminution, Paper B3, 1967. (63) Simecek, Jaroslav, Staub 26 (9), 372 (1966). (64) Sternberg, E., Rosenthal, F., J . Appl. Mech. 74,413 (1952). (65) Sugimoto, M., Endoh, K., Tanaka, T., Kngaku Kogaku, Engl. ed. 4 (21, 348 (1966). (66) Talbot, J. H . , J . Sci.Znstr.43 (IO), 744 (1966). (67) Tanaka, Tatsuo, IND. ENC. CHEM.PROCESS.DESIGNDEVELOP.5 (4), 353 (1966). (68) Telepnev, S. S . , Tsuetn. Metal. 39 ( B ) , 16 (1966). (69) Temiik, O., Vitovsky, J., Tech. Dig. (Prague) 7 (7), 542 (1965). (70) Toyama, Shigeki, Kagaku Kogaku, Engl. ed. 4 ( 2 ) , 266 (1966). (71) Turner, H. E., McCarthy, H. E., A.Z.Ch.E. J . 12 (41,784 (1966). (72) Vance, F. P., I N D .END.CHEM.5 8 (6), (1966). (73) Wiegand, H., Heinke, G., MelalloberJaeche 20 (21, 70 (1966). (74) Yashin, V. P., Vaisberg, V. M., Obogashch. Rud 11 (Z), 3 (1966). (75) Yokobori, T. Kawasaki T. Swedlow J. L. eds. Proceedings of the First International C k f e r e n c e oi Fracture held a t Sehdai,’Japan, September 1965, 3 Vols., 1967. (76) Zagury, M., Reu. Ind. Min. 47 (5), 393 (1965). (77) Zorll, U., Klinke, E., Farbe Lack 7 2 (9), 861 (1966).
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