INDUSTRIAL AND EZGISEERISG CHEMISTRY
780
linearly with the amount of free carbon dioxide in solution. At constant carbon dioxide content the corrosion rate varied linearly with the oxygen concentration except when the oxj-gen nas below some point in the region 0.0 to 0.5 p. p. m. At these low values the curve appears to flatten out. 3. At zero concentration of either of these gases, the corrosion rate mas not zero but a value dependent upon the concentration in solution of the other gas.
Literature Cited Am. Pub. Health Assoc., Standard Methods for Examination of K a t e r and Sewage, 6th ed., pp. 59-61 (1925). Bengough, G. D., Stuart, J. M., and Lee, A. R . , Proc. Roy. SOC. (London), A116, 426-67 (1927). Clark, W. M.,“Determination of Hydrogen Ions,” 3rd ed., p. 561, Baltimore, Villiams and Wilkins Co., 1928. Cournot, J,,and Chaussain, M., Compt. rend., 194, 1823 (1932). Cox, G. L., and Roetheli, B. E., ISD. ENG.CHEM.,23, 1012-16 (1931). Denman, W~L., and Bartow, E., I h i d . , 22, 36-9 (1930). Evans, E. R., and Hoar, T. P., Proc. Roy. Soc. (London), -4137, 343-65 (1932) Fraser, 0. B. J., Ackerman, D. E., and Sands, J . W., ISD.EKG. CHEM.,19, 332 (1927). Groesbeok, E. C., and Waldron, J. L., Pmc. Am. Sor. Testing X a t e r i a l s , 31, 279-91 (1931). Hall, R . E., and Mumford, -4. R . , Heating, P i p i n g Ai? Conditioning, 3, 943-59, 1041-9 (1931). Hayes, Henderson, and Staneart, Engineering Expt. Sta. Iowa St’ate Coil., Bull. 84 (1927). Lee, A. R., Trans. Faraday Soc., 28, 707-15 (1932). Lewis, G. N., and Randall, M., “Thermodynamics and Free Energy of Chemical Substances,” 1st ed.. p. 297, S e w Tork, LTcGraw Hill Book Co., 1923. McKinney, D. S.,XND. EKG.CHEJI.,Anal. Ed., 3, 192-7 (1931). S a t l . District Heating Assoc., Proceedings, 23, 273-81 (1932). Tbid.,24, 195-204 (1933). Natl. District Heating Assoc., preprint 1933 meeting. . SOC.M e e h . Schroeder, TT. C., and Fellows, C. H., T ~ u n sA.m. Engrs., 54, R. P. 54-13, 213 (1932). Speller, F. N., “Corrosion Causes and Prevention,” 1st ed., p. 228, S e w York, McGraw Hill Book Co., 1926. Walker, J. H., Heating and Ventilating, 30, No. 5 , 28-32 (1933). Whitman, W.G., and Russell, R . J., J . Soc. Chem. I n d . , 43, 193 T,197-9 T (1924). Whitman, W,G., Russell, R. P., and Altieri, V. J., IXD,EKG. CHEST., 16, 665-70 (1924). Whitney, W. R.. J . Am. Chem. Soc., 25, 394 (1903). Wilson, R. E., ISD.EKG.OHEX, 15, 127-33 (1923). Yoder, J. D., and Dresher, J. D., Combustion, 3, No 10, 18- 22 (1934).
It has been mentioned that the flow of the water in the apparatus was in the viscous region. As the mechanism of corrosion may be affected by the nature of the flow, these results are strictly applicable only to the condition in which the flow of the water is not turbulent. I n most reported cases of corrosion of steam returns, the corrosion is localized a t sections adjacent to the point of condensation, such as trap connections, where the condensate flow is slow and probably viscous. S o attempt has been iiiade to relate the results of these experiments to the rate of corrosion of steel pipe in actual practice where other factors than those considered here may have an influence. The experiments show the relative influences of oxygen and carbon dioxide on the corrosion rate, but it is the opinion of the authors t h a t it is inadvisable to relate these measurements directly to the life of a given piping installation because so many factors would have to be assumed or neglected. Acknowledgment Although these experiments were carried out entirely in the laboratory of the Xew York Steam Corporation, the authors wish to acknowledge the part played by the Sub-committee on Corrosion of the Real Estate Board of New York, the meinbers of which initiated the work and encouraged its progress. The authors wish to acknowledge also the assistance furnished by the research staff of the Kern York Steam Corporation, members of which have read this report and have made many valuable suggestions.
RECEIVED &larch 29, 1935. Presented before the Division of Industrial and Engineering Chemistry at the 89th Meeting of t h e American Chemical Society, Kew York, N. Y . , April 22 t o 26, 1935.
oasting o olubilitv of Alunite
Effect of J
LUKITE is a hydrous, basic sulfate of potassium and aluminum of the formula Kz0~3-41~034SO3 6H20, on which basis its theoretical coniposition is: potassium oxide, 11.37 per cent; alumina, 36.92; sulfur trioxide 38.66; and water, 13.05 per cent. It is of interest, therefore, as a source of potash and alumina, and is so utilized in certain foreign countries. TTithin the United States, however, although there are important deposit. of this mineral in Utah and rariouq western states (S),it has riot been utilized except to a limited extent in the raw or roasted state as a low-grade fertilizer since the war-time period of intense potash activity. Interest in utilization is being revived from the broader viewpoint of industrial planning for the western states (a); this interest ifi further indicated by pilot-plant experimentation now in progress t o test processes, the nature of which has not been published. The Utah deposits hare been the inost accurately surveyed and are conrervatively estimated (Z) to contain 3,000,000 tons of higli-grade mineral containing 10 per cent
VOL. 27, NO. 7
J . RICHkRD iDA3lS Fertilizers Investigations, Bureau of Chemistry and Soils, Washington. D. C,
potash (K2O) and little or no silica. In the same region are additional reserves whose tonnages are estimated in large figures ( 7 ) ~
Chemical Properties Aside from the patent literature, of doubtful value as a source of physical constants, little information has been published to describe the chemical properties of alunite. The usefulness of the available data often suffer: througli lack of information as to the source or character of the material under examination, since it is obvious from what has been publiihed that alunite from different deposits sonietinies differs TI idely in physical and possibly, therefore, chemical properties. It is assumed (unless otherwise stated) that, in the reqearciies reported froin American laboratories, alunite from the be5tknown domeqtic deposit-the Marysvale region of iouthern Utah-has been employed; accordingly, only reference< to
INDUSTRIAL A N D ENGINEERING CHEMISTRY
JULY, 1935
781
this work are cited as APPARENT SOLUBILITY 90 more definitely perti7 0 WT. DISSOLVED I WT. OF SAMPLE nent t o the p r e s e n t research. However, 70 there are certain 50 properties that appear to be characteristic of alunite in general, 50 30 such as s u b s t a n t i a l insolubility in the inorganic acids at ordi30 10 n a r y temperatures; and a t higher t e m IO0 peratures, solubility IO in hydrochloric, hydrofluoric, a n d s u l 80 furic acid solutions. Upon roasting, de90 composition o c c u r s , 60 w a t e r b e i n g volaW (3 tilized a t 430"initially 4: 70 Iand c o m p l e t e l y a t 40 500" C.; a t this temW (3 a perature the volatiliw 2 50 a zation of sulfur triz W oxide is initiated and 20 0 a is completed a t 30 800" C. ( 1 , 6 ) , leaving a residue of alu0 mina, potassium sulIO ALUMINA SOLUBILITY1 fate, and nonvolatile impurities, p r i n c i pally silica and ferric 60 /ALUMINA SOLUBILITY~ , 1 7 oxide. At 1200" C. the potassium and a l u m i n u m constitu80 40 ents interact to form potassium aluminate. At certain 20 60 i n t e r m e d i a t e temp e r a t u r e s (around 500" C.)] a portion of 40 both the potassium a n d aluminum sulROASTING TEMPERATURE f a t e s is r e n d e r e d FIGURE1. SOLUBILITY OF ROASTED AND UN20 ROASTED ALUNITEIN -4CIDS AT ROOMTEMsoluble in water; a t PERATURE 800" C. the potassium sulfate is r e n d e r e d completely soluble, and the alumina constituent insoluble. 0 200 400 600 000 1000 Fink, Van Horn, and Pazour ( d ) ] applying x-ray methods, ROASTING TEMPERATURE have followed the progressive decomposition of alunite FIGURE2. SOLUBILITY OF ROASTEDAYD UN(source unstated) on prolonged roasting, with the observation ROASTED ALUNITE IN ALKALIES AND WATER 4T that a t 500 " to 600" C. the diffraction patterns characteristic ROOMTEMPERATURE of alunite are displaced by those which they identify as perto a search for extraction methods that yield high-grade taining to dehydrated alum, A12(S04)3.Kk304,which in turn alumina, freed from its impurities, as a by-product of potash a t 700" to 800" C. are displaced by those characteristic of production; or more specifically, to determine the optimum "a-alumina (corundum) and Ki304 crystals." While these combination of roasting temperature and solvent, since it is observations are by nature largely qualitative, it may be obvious from previous work that the higher temperatures concluded that the patterns registered are of the predominant required for the complete liberation of the potash in waterconstituent. soluble form convert the alumina into refractory forms of Roasting a t 800" C., followed by leaching t o recover poinferior commercial value. Intermediate, there should be tassium sulfate, 'was the basic process employed during the temperatures a t which both are rendered soluble, temperalarge-scale, war-time utilization of alunite in this country; tures a t which the alumina is in a newly liberated or nascent this process yielded alumina of such an inert nature, however, state and more subject to attack by the appropriate reagent. that its purification from the contaminating iron and silica was impracticable, and its use was restricted to the manuExperimental Procedure facture of refractives and abrasives. The alunite used in this work was from the Marysvale deThe purpose of the present research is to determine soluposits (Armour properties) and had the following composibilities as influenced by roasting temperatures as fundamental
2
~
~
,
I
782
INDUSTRIAL iiND ENGINEERING CHEMISTRY TABLE I. Comosmox
Roasting Volatilization Temp. Loss
c.
Unroasted 400 550 600 650 700 800 1000
,
..
0.34 13.53 14.34 15.73 24.83 41.46 42.97
OF ----Recalculated
R?O
ROASTED ALUNITE
81~08 -Per ---ntec
9.93 9.96 11.48 11.59 11.78 13.21 16.96 17.41
Composition--FepOa
Si02
0.82 0.82 0.95 0 96 0.97 1.09 1.40 1.44
0.39 0.39 0.45 0.46 0 46 0.52 0.67
34.81 34.93 40.26 40.64 41.31 46.31 59.46 61.04
0.68
tion: potassium oxide, 9.93; alumina, 34.81; ferric oxide, 0.82; sulfur trioxide, 37.98; silica, 0.39; and water 13.26 per cent. Approximately 300-gram portions of this material, ground to pass a 100-mesh sieve, were roasted for 4 hours at the various temperatures indicated, and losses in weight were determined. From the loses observed, the composition of the respective roasted products was recalculated as the basis of the subsequent solubility determinations. These data are presented in Table 1.
VOL. 21, NO. 7
With roasting temperatures below 400 ', the acid solvents are without effect, while the caustic solvents dissolve 24 per cent of the alumina a t 400". With the initiation of water expulsion, solubility increases (more markedly however in the caustic than in the acid solvents) ; but i t is not until the liberation of sulfur trioxide occurs that maximum solubility is attained. While the liberation of the water of combinatioii may be assumed to disintegrate the mineral particle, exposing an increased surface area to the action of the solvents, the critical change that takes place on heating seems to be the decomposition of the slightly soluble dehydrated alum and the liberation therefrom of alumina in the nascent and amorphous form. This alumina, at higher temperatures undergoes transformation into the crystalline a-alumina and rapidly becomes insoluble, This gives at least a tentative explanation of the solubilities observed; the conclusion may then be drawn that the optimum roasting temperature lie3 in the region of 500" to 600" C. The marked superiority of the caustic over the acid solvents is noteworthy; a further distinct advantage is represented by the elimination of iron.
TABLETI. SOLUBILITY (IN PER CENT)OF ROASTED ALUNITE Roasting Temp., C. Original 400 600 800 1000
ti^^^ Temp., Original 400 550 600 650 700 800 1000
C.
Apparent 0.57 1.01 40.56 41.97 36.44
5 'V HCI-IhO 1.01 2.91 49.48 99.50 100.43
-5
.11!03
1.25 1.54 42.34 10.23 5.31
--------
Apparent 22.00 23.50 91:07
...
38: 21 33.36
5 N NaOH IGO 0.55 0.60
Apparent 0.64 0.73 29.69 40.92 35.85
-
Solubility in Acid Solvents "085KzO A1208 Apparent 0,57 0.78 0.46 0.65 1.04 0.62 29.05 25.98 65,11 89 51 8.58 40.01 93.41 4.12 35.26
--.
Solubility in Alkaline Solvents-------
Ai203 24.37 26.18
95: 44
9i:ii
, . .
I . .
92104 93.98
N
(.. 5.16 1.71
7
Apparent 20.97 22.03 89.15 92.39 81.48 66.08 43,12 33,61
Of the roasted (and for comparison, the unroasted) products, 5-gram portions were extracted by shaking for 4 hours at room temperature with water; with 5 A' aqueoussolutions of the following solvents, respectively-sodium hydroxide, potassium hydroxide, hydrochloric acid, nitric acid, sulfuric acid; and with a 6 per cent sulfurous acid solution. -425 per cent excess over the theoretical requirement was added in each case. The insoluble residue was Jyeighed for the determination of the over-all or "apparent" solubility and the resulting solutions were analyzed for the constituents dissolved.
I n Figures 1 and 2, based on Table 11, the curves for apparent solubility, potassium solubility, and alumina solubility have been separated in order to avoid a maze of lines, The curves representing apparent or over-all solubilities in the respective solvents are composed principally of those of potassium sulfate and alumina, requiring for their understanding an examination of the individual solubilities of the two components (Table 11). Thus, the potassium sulfate between 400" and 800" C. rapidly approaches a maximum beyond Tvhich there is no decrease a t higher temperatures; the alumina, between 400" and 600" C. reaches a maximum beyond which there is an equally rapid diminution. I n the case of the potassium constituent, the solvent employed has little action above that of the aqueous medium in which it is applied; there is some slight acceleration a t the lower temperature but none a t all, apparently, a t the higher. The action of t8hesolvent is therefore principally upon the alumina constituent.
5 N KOHIGO
-
N HzSO4K?O 3.37 3.29 36.79 69.40 68.07
Ah03
0.86 1.04 65.02 7.97 4.39
_.
1.11 Trace 65,68 83,40 88.62 93.34 95.28 97.24
6Apparent
>
AlzOa 23,65 24 59 91.44 91.29 68.29 30.87 8.55 1.42
% ' H&Oa------
0.18 0.94 21.25 42.07 35.44
-Solubility Apparent
KlO
.kilt03
Trace 0.75 26.33 93.68 94.66
0.67 0.76 23.03 9.99 4.03
in Water------K2O .&bo3
0.27 0.27
0.82 1.22
Trace Trace
3.91
11.47
3.39 ..i
..,
~ . .
36:42 32.12
,
,..
96: 3 8 96.16
..
...
3.17 Trace
Acknowledgment The author wishes to express his gratitude for the cooperat'ion and helpful suggestions of J. W. Turrentine.
Literature Cited (1) Bowley, H., J . P r o c . R o y . SOC.W . Australia, 7, 48-63 (1920-21). (2) Bur. RecZamation Bull., Nov., 1934, pp. 18-19, (3) Butler, B. S.,and Gale, H. S,,U. S. Geol. Survey, Bull. 511 (1912). (4) Fink,W.L., Van Horn, K. R., and Pasour, H. A., IND. Eso. CHSN., 23, 1248-50 (1931). ( 5 ) Mansfield, G. R., private communication. (6) Ogburn, 8.C., Jr., and Stere, H. E,, ISD. ENG.CHEM.,24, 28890 (1932). (7) Turrentine, 5. W., "Potash, a Review, Estimate and Forecast," p. 85, New York, John Wiley & Sons, 1926.
RECEIVED January
26, 1936.
GERMANY INTRODUCES SOYBEANRESIDUES FOR FLOTATION MATERIAL.A German process patented recently utilizes a slimy residue rich in phosphatides obtained from the refining of soy bean oil. The inventor of the product reports that this residual slime possesses excellent'frother-collector properties which may be used to advantage in t>heflotation of sulfidic ores in place of toluidine, xylidine, alpha-naphthylamine, dicresyldithio phosphoric acid and similar substances combining the properties of frothers with those of collectors.
A.
Etched
B . Polished
FIGURE 1. WELDZONE (a)BETWEEN 18-8 (b) AND LESSEXPENSIVE FERROUS MATERIAL (c) PRODUCED BY AN OLDER CLADDING METHOD( X 1000)
FIGURE2.
CONTACT (a)
BETWEEN
AND ELECTROLYTIC IRON (e) BEFORE HEATTREATMENT ( X 500)
18-8 (b)
Cladding of Ferrous Products A New Electrochemical Method RAYMOND R. ROGERS, Columbia University, New York, N. Y.
FIGURE 3. WELDZONE (a) BETWEEN 18-8 ( b ) AND ELECTROLYTIC IRON (cl low r e c o v e r y AFTER HEATING FOR ONE HOUR .4T 9.50 from ingot to C. ( X 750) finished b a r , plate, or sheet. It has been f o u n d t h a t “a stainless or chromium alloy veneer not more than 0.015 inch thick (28 gage) is s u f f i c i e n t to protect the surf a c e of s t e e l against most of the destructive (IS). forces” Hence attempts have been made t o c o v e r ordinary, comparaFIGURE 4. WELD ZONE (a) OF LowCARBONSTEEL(c) CLADWITH 18-8 ( b ) tively cheap, BY ELECTROCHEMICAL METHOD( X 500) ferrous materials with a d h e r e n t veneers of the more expensive iron alloys. I n this way the desired combination of strength with resistance to corrosion or heat may be obtained a t a much more reasonable price. The problem has not been easy to solve, but some progress has already been made in the desired direction.
The demand for clad materials in order to increase the use of the more expensive metals and alloys is discussed. Cladding methods proposed by previous investigators are briefly summarized. A new electrochemical method of cladding ferrous materials with (1) stainless materials, such as 18-8 chromium-nickel steel and low-carbon chromium irons, (2) high-carbon steel, (3) high-speed steel, (4) stellite, and (5) nickel is described. Photomicrographs showing the excellent nature of the clad materials produced by the new method are included.
URING the past twenty-five years many metals and alloys have been produced which exhibit remarkable resistance to corrosion, heat, abrasion, etc. A conception of the important applications of many of these materials in the leading industries, such as those in which dairy products, chemicals, and automobiles are manufactured, may be gained from the recent summary by Thum (1.9). At the present time a wide use of many of these metals and alloys is prevented because of their excessively high price. This is due (1) to the high cost of a number of the elements, such as nickel, chromium, and tungsten, (2) to the high rolling and forging cost which is many times greater than that of ordinary steel, and (3) to the
Historical The art of forge-welding is extremely old and the veneering or cladding of one metal with another was a natural develop783
