counter-ion layer (made u p of the sodium ion from the S H M P and other ions in the sclution) to move closer to the particles. Collision of t\vo particles (and subsequent coagulation) is then more likely. Contact a t a n electrode is also a method for coagulation. Heating the solution gives greater thermal energy to the particles. \vhich aids coagulation. These methods have been tried and all work with these solutions. 5. .\ silica sol \vas used to precipitate unstabilized supersaturated solutions. It gave a precipitate which settled very slo\vly (I, 2 to 1 hour). -4 very slo\vly settling precipitate might allow precipitation Lvirhin the unit without clogging the flow paths. Acknowledgment
.A literature survey by E. Gutoff and laboratory assistance of -A. J. Giuffrida and 1Iarcia E. Berg are gratefully acknoivledged. Data from field experience ivere obtained from I V . B. Iaconelli.
Brackish \Vaters,” Dept. of Interior, OS\$‘ Progress Rept. 11 (December 1956). (4) , , Kellev. K. K.. Southard. J. C.. .Anderson. C. T.. U. S. Bur. Mines Tech. Paper 625 (1941). (5) Kruyt, H. R., “Colloid Science.” Vol. 1, pp. 81, 129, 302, Elsevier, New York, 1950. (6) Lewis, IV. K., Squires. L., Broughton, G., “Industrial Chemistry of Colloidal and Amorphous Materials,” pp. 122, 183, Macmillan, New York, 1948. (7) Ibid., p. 438. (8) McBain, J. \V., “Colloid Science,“ p. 191, D. C. Heath, A-eiv York, 1950. (9) Mason, E. A , , Juda, IV., Chem. Eng. Progr. Symposium Set. 5 5 , No. 24, 155 (1959). (10) Mason, E. A , , Kirkham, T. A . Zbid.. 5 5 , No. 24, 173 (1959), (11) Rosenberg, N. \V., Tirrell, C. E., IND.ENG. CHEM.49, 780 (1957). (12) Seidell, .4.,Linke, I V . F., “Solubilities of Inorganic and Metal Organic Compounds,” 4th ed., Vol. I, Van Nostrand, Princeton, N. J., 1958. (13) Van IVazer, J. R.: Callis, C. F., Chern. Rev. 58, 1011-46 (1958). (14) V i n IVazer J. R . . Griffith. E. J., McCullough, J. F., J . A m . Chern. Soc. 77, 287 (1955). RECEIVED for review October 26, 1961 .ACCEPTED April 12, 1962
literature Cited
(1) Bell, R. N., IND.ENG.CHEM.39, 136 (1947). (2) Davies. C. W., “Structure of Electrolytic Solutions,“ I V . J. Hames. rd.. Chap. 3. IViley. New York, 1959. (3) Ionics. Inc.. “Design. Construction, Field Testing and Cost Analysis of an Experimental Electrodialysis Demineralizer for
Division of IVater and IVaste Chemistry, Symposium on Saline Il’ater Conversion. 139th Meeting, ACS. St. Louis, Mo., March 1961. LVork supported by the Office of Saline IVater, Department of Interior, under Contract 14-01-001-180.
CORRESPONDENCE ENERGY-NEW SURFACE RELATIONSHIP IN PARTICLE CRUSHING S I R : T h e research described by R. A. Zeleny and E. L. Piret [”Dissipation of Energy in Singlc Particle Crushing,” ISD. E N G . CHEM. PROCESS DESIGNDEVELOP.1, 37 (1962)] is of considerable interest. It shows a linear relationship betlveen heat generation and nelv surface produced in the crushed material, the slope of the line for quartz being equivalent to 7.7 X lo4 ergs per sq. cin. This result is similar to those \vhich I obtained in the early 1950’s [“-4 Method of Predicting the Performance of Commercial Mills in the Fine Grinding of Brittle hIaterials?” T r a n s . Znst. M i n i n g M d . 63,
that the performance ratios of the various mi!ls related to the unit impact crusher were the same for the three brittle materials examined. T h e results obtained are quoted in Table I. T h e energy losses in tne double pendulum crusher used by Zeleny and Piret are almost certainly less than in the unit impact crusher used by me: in lvnich the particles are crushed by a close1:- fitting piston sliding in a hollow anvil. Nevertheless. the rnergy usage for quartz quoted by them is gratifyingly closr to those quoted in the table.
211 (1953-4)].
G. L o d e Fairs
I n this \%rork2I compared the performance of a number of types of commercial grinding equipment with that of a unit impact crusher. I obtained a linear relationship bet\veen the net energy input and the new surface produced. I also showed
.21l11
A. Unit impact crusher B. Batch ball mill C. Swing hammer mill with coarse clearances D. Swing hammer mill with fine clearances E. Attrition mill with static classifier
Table 1. Comparison of Mill Efficiencies Aaerape EnergylUnit .Vew Surface, E r g s / S q . C m . Limestone Barytes .inliydrite 9.96 X lo4 6 . 8 1 X 10‘ 6 . 3 3 X lo1 1 . 0 2 x 105 6 . 4 3 X lo4 6.42 X 10‘
9 . 2 5 X IO‘ 1.95 2.77
x x
6 . 8 4 X lo4
x
105
1.02
1oj
105
1 . 8 9 X 10%
~~
236
General Chemicals Division, Diuision E n g i neering Department. Imperial Chemical I n dustries, Ltd., Runcorn, Cheshire. E n g l a n d
ILEC PROCESS DESIGN A N D DEVELOPMENT
6 . 0 6 X 10‘
Limestone 1 0.98
Performance Ratio Barytes iinhydrite 1 1 1.06 0.99
1.08
1 .oo
1.05
1.02
x
105
0.51
0.67
0,62
1.71
x
105
0.36
0.36
0.37
