Dec.. 1915
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
conditions of temperature, acid concentration, etc., similar t o those of the standardization. The a m o u n t of phenolphthalein used should be t h e same in each determination. An excess of t h e indicator causes low results. It has been noted in cases of alums, where iron does not interfere, t h a t best results are obtained with three or four drops of phenolphthalein solution. Larger amounts of indicator are necessary if iron is present, in order t o detect t h e end point. C O M B I X E D S U L F U R I C ACID-Provided no free acid is present, t h e combined acid is calculated from t h e titration for combined alumina. The titration multiplied by 0 . 7 2 = c o m b i x e d sulfuric a c i d , ziz., factor 2.8792 divided b y 4. Should free acid be present, as determined by t h e first procedure outlined, its equivalent should be deducted from both t h e alumina a n d combined acid. This is best done b y subtracting t h e equivalent volume in terms of N / z solution from t h e total volume titration before dividing b y 4 t o obtain percentage of A1203 or multiplying b y 0 . 7 2 t o get combined H2SOs. EXAMPLE-Titration of N/2 alkali due t o free acid = 2 . 2 cc. (1st method). Total titration of t h e hot solution (2nd method) = 80.6 cc. N a O H . T h e 80.6 - 2 . 2 = 78.4 a n d 78.4 divided b y 4 = 19.6 per cent A1203or 78.4 multiplied b y 0 . 7 2 = 56.45 per cent combined H2S04. Free acid = 2 . 2 divided b y 4 = 0 . 5 j per cent H2S0,. Sulfuric acid combined with t h e fixed alkalies is not titrated. E X P E R I 11E N T A L D A T A I N F L U E N C E OF IRON-Iron is invariably present in aluminum salts in ferric or ferrous form, generally a combination of t h e two. The amount seldom exceeds 0.8 per cent F e so t h a t comparatively large amounts of iron need not be considered here. Since the combined acid of iron in either s t a t e of oxidation titrates readily, this impurity will cause a n appreciable error unless allowance be made for t h e amount present. T h e following results were obtained on a mixture of pure potash alum with varying amounts of iron as indicated, this impurity being added as ferric a n d ferrous sulfate. The quantity of alum taken was suffi cient t o give a titration of over 69 cc. of standard alkali. The factors 0.64 for ferric a n d 0.47 for ferrous iron t o alumina were used as recommended in t h e method. Added iron 0
0 . 1 5 Fe:Os 0 . 5 Yc FezOs 1 , O g FenOa O,lyoFeO 0 . 5 ~ FeO o 1 . O % FeO
Titration l / d Titration Titration 6 9 . 4 ~ ~ . 17.35 Corrected for iron 6 9 . 8 cc. 17.45 17.39 70.85 cc. 17.72 17.41 7 2 . 5 cc. 18.12 17.48 6 9 . 6 cc. 17.40 17.35 70.65 cc. 17.66 17.43 7 1 . 5 cc. 17.88 17.41 I~
I t is evident t h a t with t h e titration representing per cent, iron present either as ferric sulfate or ferrous sulfate up t o one per cent in terms of iron oxide causes no serious error, provided t h e corrections are applied for t h e titration of t h e iron. Ferric iron tends t o cause high results. T h e fact t h a t ferric a n d ferrous sulfates are titrated is shown b y t h e results given below. Ammonium
1061
sulfate a n d persulfate are also titrated, t h e fixed alkalies are not. Results are given in terms of t h e acid calculated from t h e titration. Salt used AIz(S01)3.
Gram acid present . . . . . . . . . . . . . . . 0.300 F e S O ~ , 7 H z 0.. . . . . . . . . . . . 0 . 6 9 9 Fez(S0a)a. , , . , , , , , . , , . , . , 0.483 (NH1)2S04.,, , , , . . , . , , , 0 . 742 ( S H i ) & O s . , . . . . . . . . . . . .0 . 8 6 0
Gram acid calculated 0.299 0.636 0.612 0.658 0.850
..
Ammonia is expelled in t h e boiling solution as t h e alkali replaces it in combination. Ferrous hydroxide occludes phenolphthalein indicator t o a point of saturation. For example, i t was found t h a t one gram ferrous sulfate w:th excess N a O H would completely absorb 2 5 cc. of t h e indicator preventing i t from giving t h e desired color with caustic, whereas a n excess of t h e indicator above this amount produced t h e pink color with t h e excess caustic. T h e following results were obtained with three standard aluminum salts b y t h e usual gravimetric methods, a n d t h e results checked by t h e volumetric procedures outlined: G R A V I M E T RANALYSIS IC Per cent VOLUMETRIC Per cent ALUMINUM SULFATE Combined AlzO3. . . . . . . . . . 17.20 17. 95 A1203 Fezox.. . . . . . . . . . . 0.55 Free A l z O ~ ,.. . . . . . . . . . . . . 0 . 3 6 Fez03 .................... Correction for ferric and A1203 hv difference,. . . . . . . 17.40 ferrous i r o n . , . . . . . . . . . . 0.25 Total AiLh corrected . . . . . . 17.31 RECRYSTALLIZED POTASH A L U M T o t a l AlzOs.. . . . . . . . . . . . . . 10.77 Combined AlzOs.. . . . . . . . . 1 0 . 6 8 Iron.,. . . . . . . . . . . . . . . . . . .Trace Free A1203.. . . . . . . . .. . . . . 0 . 0 4 Total A1zOa.. . . . . . . . . . . . . 10.72 ALVMINUM CHLORIDE Combined AlzOs.. . . . . . . . . 20.45 Total Ala08 FezOz., . . . . . 20.97 Free AlzOs.. . . . . . . . . . . . . 0 . 3 3 FezOs.. . . . . . . . . . . . . . . . . . . 0.023 A1203 by difference.. . . . . . . 20.947 Total.. . . . . . . . . . . . . .. . . . . 20.78 Corrected for iron.. . . . . . . . 20.765
+
+
The end point is sharp when iron is absent, b u t with amounts of iron exceeding I per cent t h e color of t h e precipitated iron hydroxide tends t o mask t h e pink color due t o t h e indicator. Ferric iron produces a reddish pink end point; with ferrous iron a purplish pink color is observed. Four men working independently checked within 0.6 cc. in t h e titration for combined alumina, a n d within 0.1 cc. in t h e fluoride method for free alumina, making t h e limits of error due t o t h e personal factor, 0.1j per cent for total A l 2 o 3 and 0 . 0 2 per cent for free A1203. A. . . . . . . . . . . . . . . . . . 69.3 B. . . . . . . . . . . . . . . . . . . 3.8
69.4 3.7
69.8 3.8
6 9 . 2 ~ ~ . 3 . 8 cc.
S U 1X MA R Y
Rapid volumetric procedures for determining combined a n d free alumina in aluminum salts, followed by experimental d a t a showing reliability of t h e methods, are given. Impurities such as commonly occur in these salts do not interfere, with exception of iron, for which correction must be applied a s stated. The methods are of special value for works control of liquors during t h e process of manufacture of aluminum salts, a n d t h e analysis of t h e finished product in daily routine analysis. RESEARCH DEPARTMEW,G E N E R A LCHEMICALC O M P A N Y LAURELHILL, LONGISLAXD,S . Y.
RECOVERY OF AMMONIA FROM WASTE LIQUORS By E. I,. KSOEDLER Received May 22, 1915
A recent investigation of waste products in t h e plant of t h e Welsbach Company brought t o light a
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T H E J O C ' R N A L O F I X D C ' S T R I A L A N D EiVGINEERING C H E M I S T R Y
solution containing about I per cent of ammonia, which was being discharged into t h e sewer. The investigation showed t h a t this solution consisted of a mixture of three ammoniacal solutions containing, respectively, t h e following percentages of free a n d combined ammonia:
Vol. 7, NO. 1 2
When mixed together, as they appeared when run t o waste, t h e mixture approximated I per cent free ammonia a n d o . o j per cent combined ammonia. The
I n t h e selection a n d erection of t h e apparatus, t h e points of easy a n d inexpensive maintenance and operation were carefully considered, with special attention t o low labor charges a n d small steam consumption. With these points in mind t h e distilling outfit shown in Fig. I was so erected a n d set t h a t t h e waste liquor 3 3 ~ bs y gravity from t h e factory processes t o a large iron t a n k set in t h e ground just outside t h e still house. from which i t is pumped t o t h e storage tank set above the column of t h e still. This pumping is t h e only handling of any liquor during t h e complete cycle of operations-the storage t a n k supplying t h e
solution was perfectly clear a n d recovery of t h e ammonia was found t o be practicable b y t h e usual methods of distillation. T h e waste liquor was produced by t h e factory processes a t practically a constant rate throughout t h e working day, a n d this consideration influenced t h e decision t o recover by means of a continuous still.
liquid a t a constant head a t all times, whence i t flows by gravity through t h e washer, t h e coils of t h e heat exchanger, t h e heater and t h e still-the waste passing around t h e coils of t h e heat exchanger and t h e n to t h e sewer. T h e ammonia vapors pass through t h e condenser and into t h e absorber, from which t h e freshly distilled ammonia overflows into t h e storage
h-0. Per cent free 1 ......................... 3.5 2......................... 3.........................
0.5
0.1
3"
Per cent combined KH3 0.1; 0.025
0,005
Dec., 1915
T H E J O C R N A L O F I . V D C ' S T R I d L A N D ELlrGILVEERIAVGC H E M I S T R Y
tank. This t a n k is set a t such a height t h a t t h e fresh solution flows b y gravity t o t h e factory where it is available for use b y simply opening a cock. T h e steam supply for t h e still is automatically controlled. as is also t h e delivery of lime for release of t h e fixed ammonia, so t h a t i t is necessary for t h e a t t e n d a n t t o look in only once each hour or two in order t o see t h a t t h e still is operating satisfactorily. T h e bulk of t h e heat in t h e waste liquor is saved b y preheating t h e crude liquor in a heat exchanger a n d seal pot-the latter acting also as a constant flow automatic valve for t h e release of t h e waste. The consumption of lime is reduced t o a minimum b y keeping t h e milk
1063
sumption. The liquor then flows b y gravity a t a constant rate, down through t h e washer B a n d then through t h e coils of t h e heat exchanger C , back up through t h e heater D , where it 01-erfloms through t h e pipe E. into t h e volatile still F , where t h e free ammonia is driven off. The liquor then passes out through t h e pipe G into the lime leg H where it meets and is thoroughly mixed with t h e milk of lime, when it passes back into t h e still for fixed ammonia, I . Here t h e fixed ammonia is released and t h e waste liquor passes down a n d out around t h e coils of t h e heat exchanger b y means of t h e pipe L , a n d overflows t o t h e seiver. The ammonia r a p o r passes up through t h e still,
FIG.2
of lime constantly and thoroughly stirred, a n d delivering i t in small quantities a n d a t frequent a n d regular intervals. By these provisions for automatic operation, t h e cost of attendance and t h e handling of liquor, lime, etc., have been reduced t o a minimum, t h e only still charges of a n y consequence being interest a n d depreciation, a n d coal for steam. The operation of t h e still is extremely simple, and is as follows, references being t o Fig. 2 : The weak liquor is pumped t o t h e storage t a n k A by means of a small steam pump-the exhaust of which is led into t h e still t o decrease t h e s t e a m con-
bubbling through t h e doxn-coming liquors in its passage from one section t o t h e next, a n d then passes o u t through t h e coils in t h e heater D and over into t h e condenser J by t h e lead pipe M . Here t h e water vapors are condensed, a n d a part of t h e ammonia is absorbed. The condensate then flows down into t h e absorber K where i t is kept cool by means of water flowing through t h e coil N. Here t h e balance of t h e ammonia vapors are absorbed a n d t h e resulting a m monia solution passes over into t h e storage t a n k , from which it flows b y gravity through lead pipes t o t h e factory where i t is used. The milk of lime is made u p a n d kept in a n iron stir-
1064
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
ring t a n k , 0, where it is agitated continuously b y means of compressed air, which also operates t h e automatic valve, through which t h e lime is delivcred t o t h e still. T h e timing of this valve is regulated b y a needle valve a n d by-pass between t h e t o p a n d bottom of a cylinder fillcd with kerosene, in which a piston descends a n d ascends. This makes i t possible t o supply t h e lime in small quantities and at frequent a n d regular intervals, making for uniform temperatures a n d regular operation. Steam is supplied t o t h e still through a n automatic valve also operated b y compressed air, t h e controller consisting of a thermostat, depending for its operation on t h e expansion o r contraction of a liquid, t h e pressure l h u s generated serving t o operate a small air valve which in t u r n controls t h e compressed air supply t o a diaphragm valve through a,hich steam is served t o t h e still. T h e thermostat is adjusted to operate at t h e temperature of t h e t o p of t h e still, a n d serves t o keep this temperature within a range of 2' F. of t h e predetermined point. T h e concentrate runs about 28 per cent NHI at all times a n d is diluted t o t h e desired degree as used. T h e cost of operation per io-hour d a y runs approximately as follows:
___ Output, 3,000Ibs. 26 per cent NHliOH Cost per 1,WO lbr. 26 per cent NH'OH..
$6.71
. . . ,. .. . . . . . 9 2 . 2 1
T h e outfit has proved t o be simple in construction and easy t o operate a n d t h e results more t h a n come u p to expectations. WBLSBACIICo.,GLOIICBSTIR. N.
1.
A NEW GLASS; AND AN APPLICATION OF THE LOW REFLECTIVITY OF GLASS FOR RADIANT HEAT BY 12. C. SOLLIYAN ASD W C. TAYLOR Received August 19, 1915
A glass has recently been developed which is unique among borosilicate glasses in t h a t i t combines very
Pig. I-a. Dish Silvered in Quarters Outside Cake Has Adhercd o v e r the Silvci b. W h e r e Protected by Silver, Cake is Light Colored and hiperfectly Baked: Brown and weii-none~ i ~ ~ ~ h
AS
R G .
B ~ E I Dr~ GLASS A N D Trw PIXY ~ ~ . REMOVED YXDM CVZS
low thermal expansion with great resistance to a t t a c k of reagents. It is of simple chemical composition, being frec from heavy metals a n d metals of t h e magnesium-calcium-zinc group. I t s charactcristic properties are due, in part, t o very high silica content which incidentally has necessitated special technique for
12
its melting a n d working. Some of the measured properties of the glass are as follows: Specific gravity 2.25. Mean linear expansion coefficient (1-350~) 0.0000032. ATTACK BY RBACBNTS: Water a t the boiling point dissolves several times as much from the best imported laboratory glass as from this glass. SOFTENING POINT: A thread I tnm. in diameter and 23 cm. in length suspended verticdly and heated through the upper 9 cm. elongates of its own weight a t the rate of I mm. per minute at 800' C. Culinary ware made of t h e glass was found t o bake food more rapidly t h a n earthenware or metal. T h e reason for this lay in the case of t h e mctal in t h e greater reflectisity of t h e metal for radiant energy. Magnus found t h a t silver reflected 83 t o go per cent, glass only 6 t o 14 per cent of the rays incident a t a n angle of 4 5 O . l while Hageu and Rubens* give gS t o 49 per cent as t h e proportion of heat reflected b y silvcr and Coblentz's3 curves indicate 3 t o I I per cent as thc reRection b y glass. T h e following experiment, devised b y Dr. J. T. Littleton, showed t h a t this difference in reflectivity is of practical importancc in t.he baking process: A tmkinp dislz was silvered oil the outer surface in alternate quarters and a cake baked in it in an ordinary kitchen oven over a gas flame. Where the cake had been protected by the metal coating the bottom aftm baking was light colored, sticky, and imperfcctly baked while in tlie other quarters it was brown and well done. Fig. I shows the interior of the dish with the cake adhering to i t over the silvered sections, also the cake 8s it was turned out bottom up with the quartering plainly visible. Experiments showing t h a t bread bakes Laster in glass than in kin were made b y baking equal quantities of dough in two glass bread pans and two tinned iron pans of t h e same internal dimensions. The metal pans had been in service for some time a n d their onter surfaces were somewhat tarnished. T h e pans were placed in the oven of a gas stove, the t v o glass pans diagonally opposite each other and t h c metal pans diagonally opposite each other. All four were left in t h e oven t h e same length of time. Tl'hen taken
Pic. I1 ~
Vol. 7 , No.
111
B"ITOb
