TRANSPORTING SOLIDS
I
1 /L ,&
7.. Ai .
SLURRIES -
~
~
~
~~~~
-
Basic Principles and Power Requirements
D’
urmg the last century and particularly the last three decades., development of pipe line conveyance for solids has not kept pace with overall technological growth. The concept appeared in California as early as 1850 where gold-bearing sand was lifted 30 to 55 feet and flushed down inclined sluices (34). Early patents appeared for transporting coal slurries, but none attracted commercial interest until 1914 when an 8-inch cast iron pipe line, 1750 feet long, was built for transporting coal from barges on the London docks to Hammersmith power stations. In 1924, however, this line blocked and was abandoned. Then in the late twenties, a mile-long line for anthracite sludge containing 40 to 65% solids was installed at Mt. Camel, Pa. In the thirties, several more systems were installed, including a million ton-per-year line to carry rock salt in saturated solution. By 1959, 20 or more pipe lines were carrying 30 million long tons annually of mixtures of phosphate rock, sand, and clay. During the fifties, pipe lines were installed for a wide range of products including clay, sand and gravel (77), nickel-copper concentrates (78, 3 4 , borax (77), coal (3, 77, 43), ores, limestone (341, phosphate (73), and copper concentrate (72). In Bonanza, Utah, gilsonite is pumped at 700 tons per day for 72 miles across a summit 3000 feet above the mine to a refinery in Colorado (22). Other recently installed lines carry copper concentrate and deslimed tailings are listed (Table I). Coal is particularly attractive for long distance transport because of the large quantities needed by power stations and the relatively high cost of freight. Three long distances lines are operating. 18
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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
One in this country, one in France, and one in the U.S.S.R.Russia claims to have had the first but the French installation, although shorter and carrying lower concentrations, was installed 10 years previously (Table I, page 21). Future Prospects
Pipe lines seem particularly adaptable for transporting phosphates, fertilizer (72), and cement materials (72, 52) because in any event the products must be ground to fine particle sizes before use and thus advantage can be taken of the low pressure gradient offered by such finely ground material. Also partial processing in transit will probably be developed. For example, when materials of construction are available which can resist both abrasion and corrosion by hot sulfuric acid, pulverized phosphate rock could be treated in the pipe line so that the material when delivered is ready for recovering phosphoric acid (72). A similar technique has been suggested for wood chips where chemicals could be injected into a heated section near the terminus. Thus, the product when discharged would be partially pulped (34). Coal transport is a fertile area for development. Burners have been devised which can burn liquid coal-i.e., a suspension so fine that the coal does not settle even under static conditions. The economic aspects are almost ideal for slurry pipe lining because pressure losses are minimum, the market for large quantities is guaranteed, cost of
BY PIPE LINE n
grinding is compensated for by added value of the product as a fuel, and no separation problems are incurred. For example, a large line, 20 to 30 inches in diameter could collect coal from a number of mines in West Virginia and Pennsyhania for conveyance to the complex of power stations on the Eastern seaboard. A rate of 10 to 15 million tons per year is a definite economic possibility (.50) ; also, bituminous slurries could be fed to a pressure gasifier (24) and already a successful pilot plant has been developed. Further developments can be expected in this present nearly ideal situation when oil instead of water can Ix used as the conveying liquid ( 5 ) . Where oil is available near the coal mines, economic advantages are possible because the oil can serve the dual purpose of both fuel and transport medium. Burners using 60 weight % of coal in oil have been developed for blast furnaces (.?Y). New developments in slurry pipe lining depend largely on solving technical problems in processing the solids before pumping, and dewatering and drying after delivery combined with economical techniques for conveying two or mnre products at the same time. For example, special conditions which allow either use of oil as the conveying liquid or processing the solid within the line should play important roles. However, cost of actual transport is only a fraction ot installation cost and the type of comprehensive economic surveys needed before deciding to install a pipe line can be judged from published estimates (50, 53) based on the cost of transporting coal. I n addition, competing methods of transportation must be considered. Publica-
tions are available covering industrial applications and equipment problems (7, 4, 10, /2, 41, 5.5)as well as comments on the future of slurry lines (10). Baric Principles
Despite the wide interest, opinion regarding the principles of slurry pipe lining seems to differ. In 1957 and 1958 T h e U. S. Hydraulics Institute sent out two questionnaires to workers who were likely to be knowledgeable in the field (20'). To simple practical questions, many conflicting answers were received and in many instances were almost evenly divided between negative and affirmative. In selected answers compiled from the second questionnaire, agreement was only 207' on whether a large pipe line requires a higher velocity than a smaller line to keep solids fmm settling. This divergence of opinion is understandable and stems from the great number of variables which must be taken into account. As many as 32 important variables have been listed (34,including 8 physical characteristics of the solid, 10 physical characteristics of the slurry, and 14 factors in design data. For example, pipe wear from abrasive materials may override both physical and economic factors (70, 49). Many attempts have been made to penetrate the theory of suspensions (C), 27, ,32, 1.5, 17, JX) but as a science, slurry transport is etill largely in the empirical stage. Designing snch a line is clearly a job for the specialist. However, it is clear that two variables have special importance and may contain the key to slurry behavior-it., size and specific gravity of the particles. For example, the minimum power required for a slurry having 150-mesh particles is about proportional to particle specific gravity, but for many slurries having particles less than 32mesh, power is about proportional to size. A simple approach to understanding solid-liquid systems is to divide slurries into settling and nonsettling mixtures (72, 20) according. to the settling rate of particles when the liquid is at rest. Unless they are very small, particles heavier than the liquid settle at a velocity depending on size, granulometry, concentration, and apparent weight in addition to viscosity of the liquid and geometry of the container (7, 36, 56). Several methods for calculating settling velocity have been suggested (7, 8, 20, 27, 2.3, 36, 56) but none are universally valid. Therefore, settling velocity should be measured experimentally because it affects hoth the pressure gradient needed to pump the slurry and velocity needed to prevent blockage of the pipe by settling. Particle diameter, density, and concentration have considerable effect on settling velocity (20) which in turn affects slurry behavior. Slurries having settling velocities below 0.002 to 0.005 foot per second have been classed as nonsettling (20)because in most applications they behave as homogeneous or pseudo-homogeneous fluids; thus their settling tendencies can he ignored.
Mixtures with higher settling velocities should be considered settling, even though whether or not they actually settle depends on turbulence of the steam. In laminar or weak turbulent flow, significant settling does occur and the mixture behaves as a heterogeneous one; in a field of adequate turbulence complete and uniform suspension may occur, and the mixture may behave as a pseudo-homogeneous fluid. However, another discussion ( 7 7) places the dividing line between settling and nonsettling at about one tenth the velocity suggested in the previous paragraph. The theory of flow for slurries is discussed in detail (9,23, 35, 42, 44, 48,56) and many data on particle dynamics are available (28, 56). Nonsettling Mixtures. Usually these slurries show plastic properties even in water (16, 20, 51, 52 56) and viscometer or pilot tests are generally necessary to determine flow characteristics. Sometimes, they can be transported in laminar flow, and thus advantagr can be taken of lower pressure gradients (52). Examples of materials which can be made into nonsettling slurries are finely crushed limestone and clay, colloidal clays, or finely crushed coal, especially when the coal is transported in oil. Further information about nonsettling slurries has been published (7, 76, 43, 45). Unless the slurry exhibits Newtonian flow, pressure gradients can be determined only after laboratory tests have been made to determine flow characteristics. When such characteristics are established, a correlation (75) is available where the friction factor for the slurry can be read from a modified friction factor us. Reynolds number diagram similar to the normal diagram for Newtonian fluids. This correlation holds for laminar, transition, and turbulent Reynolds numbers.
20
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
Settling Mixtures. Most slurries considered for long distance transport such as silt, sand, gravel, and metallic ores and concentrates contain particles which settle in the static liquid more rapidly than 0.001 to 0.005 feet per second and thus need further consideration. For such solids, a sufficiently high velocity is needed to prevent deposition in the line. If the particles are large enough they may never be suspended at any practical velocity; instead they may move along the bottom of the pipe line in a series of jumps with or without a bed beneath them. Such behavior is known as saltation. The minimum velocity needed to prevent permanent deposition has received several different labels but critical velocity seems to differentiate best this velocity
II
Equation 1 is intended only for settling slurries. T o obtain pressure gradients for nonsettling slurries in turbulent flow, the pressure gradient of the equivalent true liquid was suggested. To solve Equation 1, the mean drag coefficient of the particles is needed which cannot be measured directly; rather, it must be calculated by reference to the particle settling velocities and diameter of an equivalent sphere. The equation has rarely been tested on fluids other
from settling velocity in a stationary liquid. The term is appropriate because the pressure gradient in the pipe is minimum at about this velocity (6, 7 7, 33, 37) which is generally that used for designing a slurry pipeline. On an empirical basis, a number of attempts have been made to correlate critical velocity with the other parameters (7 7, 25, 29, 44, 47, 48). A correlation for the minimum power required to transport a slurry (54) has been derived, and effect of particle diameter and specific gravity on the particle distribution and velocity relative to the liquid has been studied (38). From 1948 to 1952, Durand and Condolios did the classic work on pressure gradients for settling slurries in water using a wide range of screened solids in four pipes from 1.5 inches to 10 inches in diameter (77, 79). An empirical relationship was derived between the pressure gradient in a horizontal pipe and concentration and velocity of the slurry, pipe diameter, and particle characteristics. T h e correlation since has been broadly confirmed (70, 77, 20, 33, 54, 55). A somewhat simplified form of this relationship is
P I - P for water than water; (r - 1) is a special case of -
P
where p' and p are densities of the solid and fluid, respectively. Should the correlation hold for other fluids it may have to be modified further to account for slurry viscosity (5),particularly if viscosity is not constant (30). Slurry velocity is defined as the total discharge per unit cross-sectional area of the pipe, and in measuring pressure gradients, the results are recorded as gradients for a series of slurry velocities and concentrations. Figure 1 shows a typical plot of these results for heterogeneous slurries carried at liquid velocities above the critical velocity. At this velocity bed formation begins, which is increased as the velocity decreases. Thus, free pipe area is reduced and pressure gradient increases. Curves similar to those of Figure 1 are obtained with large particles transported in saltation, although the increase of pressure gradient over that for water is greater, and the minima mark the formation of a stationary bed. The Durand correlation applies to both types of transport, and although most of the original work was done with sand and gravel, the correlation was shown to be valid for particles of plastic and corundum (specific gravities, 1.60 and 3.95, respectively). Subsequent
where in units of feet per second, i, is pressure gradient due to the mixture in feet of water per foot of pipe and i, pressure gradient due to water flowing at the same velocity. C is volumetric concentration of the solids; D,pipe diameter in feet; s, specific gravity of the solids; V, mean slurry velocity in feet per second ; g, acceleration due to gravity in feet per second2; C ,, mean drag coefficient of the particles; and K , a parameter dependent on particle surface, shape, and granulometry.
Operator
Estd. Cap. Tons/ Hr.
Ref.
Pips Length,
Slulry Velocity, Concn. Pipe Dia.,
Miles
Solid Site
In.
Wt.
%
1
Ft./Sec.
Coal Pittsburgh Consol. Coal Co:
7, 4 3
150
Houllieres du Bassin de Lorraine, Ca rling, France
43
250
Norovolynskaya Mines,
3
U.S.S.R.
1
14 Mesh X 0
'/8
220
'/32
in. X in.
!
108
o
1
5l/,
xo
38
10.75
4'/r5l/*
15
25-30
12
50
7-10 43/4
Ground Limestone and Clay Trinidad Cement Ltd.
I
52
I
50
I
30 microns
1
6
I
8
I
48
1
4
Copper Concentrate6
I
Anaconda Co., E l Salvador, Chile
Deslimed Flotation Tailings
I
Anaconda, Mont. I I 2 l d I 7 I I I a To become inactive in 7963. b Other similar developments planned in South America ( 12). 0 Has been transporting about 800 tons per day sinu January 7959. Company plans to extend line 60 miles to bring copper concentrates to the coast entirely by gravity. 20,000 tons per day for dam building. VOL. 5 5
NO. 8 A U G U S T 1 9 6 3
21
investigations have confirmed the correlation for sand, but little published data related to materials of greater specific gravity are available. An exception is a publication (33)which describes the use of graded lead and steel spheres in an aqueous suspension flowing in a l/Z-inch diameter tube. The results can be correlated with the Durand-Condolios equation if different values of K and a different exponent are used; that is, at a particular velocity, K and the exponent depend on the material and size of the particle. One explanation is that K in the Durand-Condolios equation is not actually a constant, but rather it contains a compensating group which depends on solids density and particle diameter. Although these variables are already included in the equation, further groups could be necessary, especially for high density particles. Another investigation using aqueous nickel suspensions in a 1-inch pipe also suggests that K depends on particle density (77). Considerable scatter is usually found in the data of any one worker because slurry pressure gradients and concentrations, especially a t high slurry velocities, are difficult to measure. Even though the correlation seems adequate for preliminary investigations, pilot tests are necessary before undertaking extensive design. Computing Minimum Horsepower for Transport
An IBM 1620 computer was used to evaluate effects of those variables in Equation 1 which determine the excess pressure gradient factor i, - i, caused by solid particles in water. A number of solids throughputs was used with an over-all pumping efficiency of 60y0 and a K value of 85. First, a solids specific gravity and throughput were chosen for one particle diameter, and then the horsepower per mile required was calculated for varying slurry velocities and pipe diameters, the concentration being dependent on the other parameters. The minimum horsepower per mile was determined by inspecting the computer-derived tables, bearing in mind the critical velocity of the slurry under the particular conditions. T h e calculation was repeated for other particle diameters, solids specific gravities, and throughputs, using the following range of variables : throughputs, 1 to 15 million tons per year, assuming full time operation; specific gravities, 1.5 to 10; particle sizes, 10 microns to 2 mm.; pipe inside diameters, to 30 inches in 2-inch increments ; and slurry velocities, to 15 feet per second in 1 foot-per-second increments. Pressure gradients were limited to 1000 feet of water per mile (about 500 p.s.i. per mile), although this is too high for long distance transport because pressure-boosting stations are required about every three miles. Nevertheless, the figure was used, partly to allow for relatively short lines and partly to cover a wider range of particle size. Lower cutoff figures mean that many curves of minimum horsepower per mile us. particle diameter cannot be completed. Volumetric concentrations were limited arbitrarily to 50y0,which appears to mark the practical limit for long distance transport of coal at the present time. The pipe line of the Consolidated Coal Co. of Ohio carries this concentration. 22
INDUSTRIAL A N D ENGINEERING CHEMISTRY
As recommended for nonsettling slurry, pressure gradients were calculated as though the mixture were a Newtonian having the density and viscosity of water. Such a liquid is called the equivalent liquid. Results of the calculations are subject to certain limitations and therefore they are intended only to illustrate the effects of variables and not to provide design information. Two major limitations are involved : 1. Particles in each slurry were assumed to be of a single mesh and the Durand-Condolios empirical correlation was used. This correlation as stated in Equation l is valid only for sized particles, although it can be extended to mixtures of sizes. T h e main difficulty is in determining the effective mean particle diameter or drag coefficient. In mixtures, fine particles affect the pressure gradient and may reduce it considerably if they are present in sufficient proportion ( 7 7 ) . Also, particle shape can affect drag coefficient and thus pressure gradient ( 7 7). 2. For particles of a given size and specific gra\,ity, settling velocity is reduced as concentration increases and thus drag coefficient is increased. However, to simplify the large number of calculations involved in the analysis, the drag coefficient used is that of a single particle. This procedure parallels other successful correlations (7 7 , 54, 55) and in actual transport, it could be that variation of drag coefficients with concentration is relatively unimportant, except at high concentrations. However, the calculation if anything will be on the pessimistic side. Because of these limitations, Figures 2, 3, 4, and 5 are presented only to illustrate effects of the variables, rather than to provide design information. Effect of Equivalent Particle Diameter. For a given throughput of any particle diameter and specific gravity, there is only one combination of concentration, velocity, and pipe diameter for minimum horsepower, although choice of velocity and pipe diameter usually is not critical. I n some of the figures the curves are not smooth because fairly large increments of velocity (1 foot per second) and pipe diameter (2 inches) separate adjacent points. Figure 2 shows influence of particle diameter on the minimum horsepower/mile required to pump slurries. The slurry curve approaches a maximum when the particle size is 2 mm. (9 mesh) ; experimental investigations using sand and coal have shown the surprising result that the pressure gradient is practically constant with further increase of particle size, the pipe diameter, slurry velocity and concentration being held constant (77, 76, 55). Curves for other particle specific gravities give a similar picture of the great effect of particle diameter (Continued on page 24)
H . S. Ellis is a research engineer, P. J . Redberger, a mathematician, and L. H . Bolt a research engineer w i t h the Research Council of Alberta, Edmonton, Alberta. AUTHORS
and, the effect becomes even greater as specific gravity increases. An engineer responsible for designing a slurry pipe line system must determine carefully what degree of grinding before transport would be paid for by the saving in transport costs. To the extent that material can be more economically used after transport in a finely ground condition, grinding cost can be omitted from the transport costs. One company (52) found that milling and pumping limestone are cheaper than dry milling, because water facilitates the process. However, cost of partial dewatering remains which is usually necessary before the material can be used. Durand and Condolios found experimentally that the pressure gradients of aqueous nonsettling slurries can be calculated using the usual friction factor, Reynolds number curves in the same way as for true (Newtonian) liquids of the same density, the viscosity of water being inserted in the Reynolds number. The values of pressure gradient and horsepower per mile for all the nonsettling slurries in the figures were calculated in this way and the curves in the nonsettliig region are shown dotted. I n Figure 2 a safe minimum speed at a particle diameter of 10 microns was judged to be 3 feet per second, giving a concentration for the 1 million tons per year throughput of 37% in an 8-inch line. This diameter was chosen to give the greatest concentration possible below the arbitrary limit of 50% at the selected speed and throughput. The corresponding horsepower was plotted, and this point was joined to the point for the 50micron particle sue; at this latter diameter the Durand correlation and the equivalent-liquid curve gave a very similar value for the horsepower per mile. The foregoing procedure for calculating the minimum horsepower
of nonsettling slurries can only give approximate results in this region, mainly because of the uncertainty in choosing slurry velocities. But it seemed worthwhile to cover the full range of particle diameters as accurately as possible. As particle sue increases, the curve for the equivalent liquid falls below that of the Durand-Condolios correlation, and for the largest particles it would predict less than a half of the horsepower per mile given by the correlation. The danger of using the equivalent-liquid curve for settling-slurry calculations as has sometimes been done, is thus clearly evident. The Effect of Partide Speci6c Gravity. Figure 3 shows the effect of particle specific gravity where curves of minimum horsepower per mile us. equivalent particle diameter are plotted for a throughput of 1 million tons per year. Slurries with a particle specific gravity of 1.5, such as coal, are nonsettliig at particle sizes below 100 microns, and a velocity of 3 feet per second was taken as the probable minimum speed for a particle diameter of 10 mimns, giving a concentration for this throughput of 42% in a 10-inch line. Perhaps these partides can be pumped safely at a lower velocity, but the large pipe diameter necessary to give the required throughput would probably be uneconomical. I n fact economics might dictate a higher velocity than 3 feet per second to reduce the pipe diameter below 10 inches. Velocities were assumed at 10 microns for the other spec& gravities as shown on the curves, and the pipe diameter was chosen to give concentrations as near as possible to the l i i i t of 50%. The points at 10 microns were then joined by dotted lines to the nearest point estimated to represent a settling slurry calculated by the Durand-Condolios correlation. At the latter points the
~ i 2. gV-tion ~ of minimum horscpo~unper mile, ruing cquiualmt p&lc diameter, r c p i c d for a m U i m trmrpcrycar of sandfarfuN tim opaatim. Range only is sho2un for solids rmmtration md sluny ocloliricr
FipK 3. Effectof particle spemJic gravity. Solids thoughput, 1 million t a u p e r y e a . Range only is shown for solids commtrotion and sluny uclocitilr
I
24
INDUSTRIAL A N D ENGINEERING CHEMISTRY
L
horsepower per mile calculated from the correlation and that applicable to the equivalent liquid coincided closely up to a specific gravity of 4. As specific gravity increased, the correlation gave values of horsepower per mile increasingly below those for the equivalent liquid, suggesting that the Durand-Condolios correlation does not apply well at small particle diameters and high specific gravitia. With increase of particle size, the slurry curve rose above that for the equivalent liquid in a manner Similar to that shown in Figure 3. Effect of Solid Throughput. Proponents of pipe line transport of coal believe that the present coal pipe l i e s are only the beginniig of what is in store for the future. Ambitious plans have been discussed, including the pipe line transport of coal through a network of feeder l i e s to the complex of power stations on the U. S. eastem seaboard. The U. S. Department of the Interior has published a full economic report on such a project and on two other similar coal slurry projects involving pipe lines from southern Illinois to Chicago and from Utah to California (50). All were judged to have attractive economic potentials when compared with present rail rates. The minimumhorsepower per mile at various particle diameters was therefore worked out for three different coal throughputs (Figure 4). Whereas a million tons per year of any single sized coal could most economically be transported in a 6-inch line, 5 million tons per year would demand a 12- or 14-inch l i e and 15 X 108 tons per year, which might be envisaged for projects similar to thosementioned above, would need an 18- to 30-inch l i e . If liquid coal were used, the choice would fall somewhere between a 24-inch line, demanding some 150 horsepower per mile and a 30-inch l i e which would demand less than half this horsepower but which
would cost about 25% more to install. The choice of the exact diameter and consequent operating velocity would depend upon capital, depreciation and maintenance costs of the pipe lines compared with those of the power stations, plus the annual pumping costs. Similar remarks apply to the 5 million tons per year throughput where thechoice might lie between a 14-inch (illustrated) or a 16-inch line. The actual pumping cost per million tons of coal per year is lowered very little by increased throughput, and even may be increased at small particle diameters, unless the larger lines are used at high throughputs. Figure 5 compares the m i n i u m horsepower per mile per million tons a year for the same three throughputs of Figure 4. For settling slurries there is a slight reduction in the relative pumping horsepower as throughput increases, but this changes to an increase at the smallest particle diameters unless use is made of large diameter pipes. For example, the 15 million tons per year throughput with 10-micron particle diameter in the 24-inch l i e would need nearly 10 horsepower per mile per million tons a year compared with 5.6 for the 1 million tons per year throughput. But the horsepower per mile of the larger throughput could be lowered to 4.4 by use of a 30-inch line. Similarly, the horsepower required by the 5 million tons throughput could be kept down to 5.0 by using a 16-inch instead of a 14-inch line which requires 7.4 horsepower per million tons. I n considering these figures, it should be remembered that about 80% of the costs of pipe line transportation are capital charges. Although there appears to be little economy in the actual pumping costs per million tons of coal a year for larger throughputs, a considerable saving in capital costs per ton of coal delivered could be realized.
Figure 5. P o w repimats pv milion Imu of cod p a yam fa three thTooughptlls
I
I VOL 5 5
_-
NO. 8 A U G U S T 1 9 6 3 -
25
REFERENCES (1) Aubathier, P., “Hydraulic Transport of Coal,” World Power Conf. 111A/1,Madrid, 1960. (2) Babcock, H. A , , “State of the Art of Transporting Solids in Pipelines,” Am. Inst. Chem. Engrs., Denver, Colo., 1962. (3) Balbachan, Y. I . , “First Project for a Long Distance Coal Pipeline,” Ugol Coal Mac?. itloscow, 38-40 (August 1957) ; Fuel Abstracts, p. 27, January 1958. (4) Barth, W., “Physical and Economic Problems on the Transport of Solids in Liquids and Gases,” Ciiemie Zng. Tech. 32, No. 3, 164-71 (1960). In German. (5) Berkowitz, N.: Moreland, C., Round, G. F., “Pipeline Flo\v of Coal-in-Oil Suspensions,” Can. J . Chem. Eng. (June 1963). (6) Blatch, N. S., “Transport of Sand in Pipes,” Trans. Am. Soc. Civ. Engrs. 57,400 (1906). (7) Brown, G. G., others, “Unit Operations,” Chap. 7, SViley, New York, 1953. (8) “Calculation of Terminal Speeds,” Eng. 150, 441-4 (1940). (9) Chien, K.,“Present Status of Research on Sediment Transport,” Trans. Am. SOC. Civ. Engrs. 121,833-68 (1956). (10) Condolios, E., Couratin, P., Pariset, E., “Transportation of Solids in Conduits : Industrial Application Possibilitics,” Engineering J . 44, 6 , 62-7 (1961). (1 1) Condolios, E., “Hydraulic Transport of Solid Materials in Pipes,” Am. Mining Congr. Conv., Seattle, 1961. (12) Costantini, R., “Pipelines Show Good Potential for LongDistance Transporting of Solids,” Min. Eng. 13, 8, 977-81 (1961). (13) Custred, U. K., “Hydraulic Transportation of Phosphate at Sydney Mine,” Min. Eng. 13,279-81 (1961). (14) Dauber, C. A., “Pipeline Transportation of Coal?” Coal Age 62, Pt. I, 84-7 (April, 1957). (15) Dodge, D. W., Metzner, -4.B., “Turbulent Flow of KonNewtonian Systems,” A.I.Ch.E.J. 5 , 2189-204 (1959). (1 6) Durand, R., Condolios, E., “Technical Information about the Transport of Solids in Pipes,” Centenary Congr. Mineral Industry, France, 1955. (17) Ellis, H. S . , Round, G. F., “Laboratory Studies on the Flow of Nickel-Water Suspensions,’’ Bull. and ProG., Can. Inst. Min. Metall., in press. (18) Fraser, D. A., “Pipeline Transportation of Concentrates,” ‘ Mining Congr. J . 46, 44-8 (March 1j60). (19) Gibert, R . , “Transport Hydraulique et Refoulement des Mixtures,” Ann. des Ponts et Chaussees 30, 307-486 (1960). (20) Govier, G. W., Charles, M. E., “Hydraulics of the Pipeline Flow of Solid-Liquid Mixtures,” Engineering J . 44, 8, 50-7 (1961). (21) Harris, C., “Correlation of Sedimentation Rates by Dimensionless Groups,” Nature 183,No. 4660, 530-1 (1959). (22) Henderson, J. H., “Gilsonite Slurry Pipeline,” Am. Inst. Chem. Engrs., Denver, Colo., 1962. (23) Heywood, H., “Uniform and Nonuniform Motion of Particles in Fluids,” Symposium on the Interaction between Fluids and Particles, 3rd Congr. European Fed. Chem. Eng., London, 1962. (24) Huff, W. R . , \Villmott, L. F., “Development and Operation of a Pilot Plant for Feeding Bituminous Coal Slurry to a Pressure Gasifier,” U. s. Bureau of Mines, Rept. 5719, 1961. (25) Hughmark, G. A., “Aqueous Transport of Settling Slurries,” IND.ENG.CHEM.53, 5, 389-90 (1961). (26) Hydraulic Institute, New York, “Correlation of Data from Two Surveys on Velocities and Friction Losses Involved in Pumping Fluid Mixtures.” (27) Kurgaev, E. F., “On the Viscosity of Suspensions,” Dokl. Akad. Nauk. S.S.R. 132,2, 392-4 (1960). (28) Lapple, C. E., “Particle Dynamics,” Chemical Engineers’ Handbook (J. H . Perry, Ed.), 3rd ed.? p. 1017-21, McGrawHill, New York, 1950. (29) Lowenstein, 3. G., “Design So Slurries Can’t Settle Out,” Chem. Eng. 6 6 , 1, 133-5 (1959). (30) Moreland, C., “Viscosity of Suspensions of Coal in Mineral Oil,” Can. J . Chem. Eng. 41, 1, 24-8 (1963). (31) Moreland, C., “Pipeline Transportation of Solids,” Proc. 11th Ann. Dominion-Provincial Coal Research Conf., Saskatoon, Sask., Canada, 1959. (32) Murphy, G., Mitchell, W. I., Young, D. F., “Mechanical Characteristics of Slurries,” U. S. Atomic Energy Comm., I.S.C. 236, 237, 1952. 26
INDUSTRIAL AND ENGINEERING
CHEMISTRY
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