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562
acidity due t o previous applications equivalent t o 5 , 7 0 0 lbs. of calcium carbonate. As an average of t h e results from seven plots which afford d a t a for this measurement t h e reduction in acidity is 2,864 lbs. by t h e Hopkins method, 2,674 b y t h e vacuum method, and 2,388 by t h e hydrogen electrode, while t h e MacIntire, Hutchinson and modified Tacke methods show reductions of 1,243, 1,279, and 1,375 lbs., respectively. T h a t any method will show a greater reduction i n acidity t h a n actually occurs and remains a t t h e time of sampling seems extremely doubtful. As suggested above, t h e vacuum method appears t o furnish t h e most trustworthy measure of t h e total lime requirement and i t also seems safe t o assume t h a t t h e hydrogen electrode will give results in substantial agreement with t h e vacuum method if sufficient time is allowed. If these methods are accepted as standards, then t h e Hopkins method seems t o give correct results when used t o measure t h e reduction in soil acidity b y applications of lime. It may also measure with accuracy the most immediate lime need, although i t does not measure t h e total power of a soil t o decompose carbonates. If we assume t h a t t h e reduction in acidity should be approximately t h e same for all limed plots, t h e Hopkins method and the hydrogen electrode show t h e highest percentage consistency. CONCLUSIONS
I-A
method has been proposed for determining t h e power of a soil t o decompose calcium carbonate which approximates t h e results obtained b y use of t h e hydrogen electrode. 2-The Hopkins and t h e hydrogen electrode methods show t h e highest percentage consistency for measuring t h e reduction of acidity for limed soils. THE DETERMINATION OF ZIRCONIUM IN STEEL' By G . E. F. Lundell and H. B. Knowles BUREAUO F STANDARDS, WASHINGTON, D.c. Received November 3, 1919
1-1
NTR 0 D U C T I 0 N
Any generally applicable method for t h e determination of zirconium i n steels must make provision for a variety of elements which may be present as intentional or as accidental alloying constituents. Among such elements are titanium, aluminum, chromium, tungsten, vanadium, phosphorus, and, less commonly, uranium and cerium. Since zirconium steels very often contain aluminum and titanium, i t is most desirable t h a t any proposed method for t h e determination of zirconium should also provide for t h e determination of these analytically related elements in t h e same portion of steel. I t is t h e purpose of this paper t o give a critical review of the methods which have been published for this determination, t o present methods which have been considered, and t o describe a method which has been worked out a t the Bureau of Standards. This method is not considered final and ideal, b u t i t is t h e result of an effort t o meet t h e requirements listed above. '
1
Published by permission of the Director of the Bureau of Standards.
Vol.
12,
No. 6
11-HISTORICAL
have described a method for t h e analysis of alloys of nickel and zirconium, which makes provision for silicon, tungsten, nickel, aluminum, zirconium, manganese, and small percentages of iron. Elements such as titanium and chromium were n o t encountered by t h e authors named, and therefore no provision was made for their separation and determination. Their method cannot be applied directly t o t h e analysis of material high in iron, like zirconium steels. P E R G C S O N METHODs-Ferguson2 has given three optional methods for t h e determination of zirconium in steel. Abstracts of these methods are given with comments below. K E L L E Y A N D AIEYERS'
Method I-The steel is dissolved in hydrochloric and nitric acids, the solution treated with sulfuric acid, evaporated to dryness, and the residue cooled and taken up in dilute sulfuric acid. The silica is filtered off, ignited, treated with sulfuric acid in excess, then with hydrofluoric acid; the solution is evaporated to the appearance of fumes, diluted and filtered. The filtrate is added to the previously obtained filtrate and the whole is nearly neutralized with ammonium hydroxide, treated with ammonium bisulfite and heated to boiling until the iron is reduced. The solution is cooled, made slightly alkaline with ammonium hydroxide, then slightly acid with hydrochloric acid, boiled, and precipitated with phenylhydrazine. After digestion, the precipitate is filtered off, dissolved in hydrochloric acid, reprecipitated with phenylhydrazine after ammonium bisulfite reduction, filtered, washed, ignited, and weighed. The ignited oxides are fused with sodium carbonate, the melt is treated with water, and aluminum separated by treatment with sodium hydroxide followed by filtration. The insoluble residue is ignited and fused with potassium pyrosulfate; the melt is dissolved in water, and the,zirconium precipitated with ammonium hydroxide if iron is absent, or with phenylhydrazine after reduction when iron is present; the precipitate is filtered and ignited t o zirconium oxide.
This method, if we grant quantitative separations, is still open t o t h e following objections: I-No provision is made for titanium, which is a common constituent of zirconium steels and which will accompany t h e latter through all t h e separations a n d finally be counted as zirconium oxide. 2-No provision is made for chromium, which is a possible contaminant of zirconium steels and which will be counted as aluminum in this method if t h e carbonate fusion takes place in a n oxidizing atmosphere, a n d as zirconium if t h e atmosphere is reducing. 3-Phosphorus in t h e steel will be present as phosphorus pentoxide in t h e phenylhydrazine precipitate and will be reckoned finally as aluminum. 4-Cerium, uranium, and vanadium will also cause complications, t h e cerium being counted as zirconium, while vanadium and uranium will go with t h e aluminum. Method 11-In this method Ferguson proceeds as in Method I until the reduced iron solution has been rendered slightly alkaline. A t this point the solution is treated with z cc. of concentrated sulfuric acid, diluted t o 400 cc., and disodium phosphate added. After boiling and digestion, the precipitate is filtered off, washed with one per cent sulfuric acid, then with hot water, ignited, blasted, and weighed as zirconium phosphate, for which the zirconium factor 0.3828 is given 1 2
THISJOURNAL, 9 (1917), 854. Eng. Mzning, 106 (1918), 793.
June,
1920
T H E J O U R N A L OF I N D V S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
This method is open t o the following objections: I-The zirconium phosphate which is finally weighed is of indefinite composition and consequently no t r u e zirconium factor can be given.’ a--n’o provision is made for titanium, which will certainly contaminate t h e zirconium phosphate if hydrogen peroxide is not added before t h e phosphate precipitant. 3-Aluminum, chromium, and iron, if present, will contaminate a zirconium phosphate thrown out in such low acidity (one per cent by weight), as shown by Nicolardot and Reglade.2 4-No provision is made for t h e determination of titanium and aluminum. ,Vethod 111-In this method Ferguson takes the combined aluminum and zirconium hydroxide from the second phenylhydrazine precipitation, dissolves them in 40 cc. of hot I : I hydrochloric acid, dilutes to IOO cc., cools, and precipitates with a cold 6 per cent water solution of cupferron. The precipitate is washed in succession with cold dilute hydrochloric acid, water, ammonium hydroxide, and again with water, and ignited t o zirconium oxide.
This method is open t o t h e following objections: I-No provision is made for titanium, which is therefore counted as zirconium. 2-Cupferron precipitates iron and consequently t h e second phenylhydrazine precipitate must be absolutely free from iron. 3-Vanadium, cerium, and uranium would probably cause contamination of t h e final precipitate. 4-No provision is made for t h e determination of aluminum. JOHNSOK’S ~ETHo~-Johnson’s~ method for the determination of zirconium in steels is as follows:
The steel is dissolved in sulfuric acid with minimum oxidation; the residue is filtered off, ignited, and treated with hydrofluoric and sulfuric acids; the solution is evaporated till white fumes escape and added t o t h e main solution, which is then treated with ammonium hydroxide until t h e first appearance of a black precipitate. The precipitate containing zirconium and aluminum, together with a little iron, is filtered and dissolved in hydrochloric acid; t h e solution is ozidized with sodium peroxide, boiled with sodium carbonate, and filtered. Most of the aluminum is thus separated from iron and zirconium. The remainder is separated by a second treatment. Aluminum is recovered from the filtrates by adding hydrochloric acid until the solution is no longer alkaline to turmeric, filtering off the aluminum hydroxide, dissolving in acid, and reprecipitating with ammonidm hydroxide. The sodium peroxide-carbonate precipitate containing iron and zirconium is dissolved in sulfuric acid, and treated with disodium phosphate and then ammonium hydroxide until a precipitate starts t o form. After digestion, the mixture of zirconium and iron phosphates plus some silica is filtered, washed with water, ignited and treated with hydrofluoric and sulfuric acids; the acids are evaporated till white fumes appear, the residue washed into a beaker, warmed t o dissolve ferric sulfate, filtered, and the residue ignited to “zirconium phosphate,” for which the zirconium factor 0.3838 is given. 1
G. If. F. Lundell and H. B. Knowles, J. Am. Chem. Sac., 41 ( 1 9 1 9 ) ,
1801.
Johnson’s method is open t o t h e following objections : I-The zirconium value cannot be correct except through a most fortunate balancing of errors. Washing of zirconium phosphate with water causes hydrolysis with formation of a basic phosphate of indefinite composition. 2-The prescribed treatment of the impure basic phosphate results in further loss of phosphoric acid, and no definite composition can be ascribed t o t h e ignited residue. 3-No provision is made for t h e determination or t h e interference of titanium which is a frequent constituent of zirconium steels. T R A V E R S ’ METHOD-TraVerS” method for t h e determination of zirconium in steel is as follows:
Silicon is first eliminated and then the greater part of the iron by an ether separation. After boiling out the ether, a double precipitation is made by Chancel’s2 sodium thiosulfate method. The precipitate is ignited, fused with potassium carbonate, extracted .with water and the aluminum determined in t h e filtrate. The residue is dissolved in hydrochloric and nitric acids (any insoluble matter being fused and recovered), and the solution again treated by Chancel’s method. The resulting precipitate is ignited, and weighed as Zr02 plus TiOz. It is then fused with potassium pyrosulfate and the melt taken up with water; to the solution is added a n excess of hydrogen peroxide, the precipitate formed is filtered off, and ignited to 25-02, while TiOz is determined colorimetrically in the filtrate.
Travers’ method is open t o t h e following objections: I-No provision is made for such possible interfering elements as chromium, tungsten, vanadium, and phosphorus. 2-Yo experimental d a t a are given which might cast light on t h e sharpness of t h e separations, particularly t h e separation of zirconium from titanium by precipitation with hydrogen peroxide in dilute sulfuric acid solution. E P A R A T I 0S S
111-S
Compt. Rend., 168 ( 1 9 1 9 ) , 350.
3
Chem.
Ep
Met. Eng , 20 ( 1 9 1 9 ) , 588.
C 0 NSI D E R E D
B E F 0R E
A D O P T 10 N
OF
BUREAU O F STANDARDS METHOD ( I ) HILLEBRAP;D’S3
JIETHOD
O F P R E C I P I T A T I K G ZIR-
H~SOI-H~O S O~ LUTIONNicolardot and Reglade4 have shown t h a t a solution must contain 2 0 per cent by weight of sulfuric acid in order t o prevent contamination of zirconium phosphate by ferric phosphate. Experiments upon solutions of steels treated with known amounts of zirconium, titanium, and aluminum as shown in Table I demonstrated t h a t this method is not reliable for such materials, even though t h e weighed phosphate is analyzed for its contaminants. This method has t h e additional disadvantage t h a t it requires separate determinations of aluminum and titanium. It may serve for t h e q u a l i t a tive detection of zirconium in 5-8. portions of steel when this element is present in amounts over onet e n t h of one per cent. CONIUM
1 2
2
563
8 4
AS
PHOSPHATE
IN
Chzm. et Ind., 2 ( 1 9 1 9 ) , 385. Compt. Rend., 46 (1858), 987. U. S. Geol. Survey, Bulletan 148, and subsequent editions. Compt. R e n d , 168 ( 1 9 1 9 ) , 348.
T H E J O U R N A L OR I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
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TABLEI (Steel taken 5 g. Precipitating conditions: 300 cc. total volume, 2 0 per cent sulfurid acid (sp. gr. 1.84) by weight, 20 cc. hydrogen peroxide, 5 per cent ammonium nitrate wash water)
Gi3rs.G. G. G. G. G. G. G. G. 1 2 0.0500 0,0480 0.0500 0.1641 0.0005 0,0197 0,0366 -0.0134 18 0.0500 0.0480 0.0500 0.1641 0.0006 0,0079 0,0480 -0.0020 2 0.0099 0.0100 0.0099 0.0172 0.00591 -0.0040 .. 0.00581 -0.0041 18 0.0099 0.0100 0,0099 0.0168 1 Represents Zr calculated upon t h e assumption t h a t t h e precipitate was pure zirconium phosphate. 2 3 4
..
(2) D I R E C T
PHATE I N
PRECIPITATION
HzS04
OF
.. ..
ZIRCONIUM
PHOS-
SOLUTION WITH ALL O F S T H E I R O N I N
FERROUS CONDITION-This method was not studied because of t h e following apparent drawbacks : ( a ) If precipitation of zirconium as phosphate is complete, t h e precipitate will certainly be contaminated b y titanium and probably also b y iron. ( b ) The determination of aluminum and titanium would require new portions of material and t h e development of separate methods of analysis.
(3)
BAILEY’S~ METHOD
FOR
SEPARATING Z I R C O N I U M
H2S04 H202-Hillebrand2 found t h a t t h e complete precipitation of zirconium in dilute sulfuric acid solution by means of ordinary hydrogen peroxide is impossible. A like observation has been made b y P i ~ c i n i . ~Even though complete precipitation is possible with a stronger reagent like perhydrol, i t does not appear likely t h a t a clear-cut separation of zirconium from iron and other elements can be had b y this method. It has also t h e disadvantages mentioned in ( b ) above under ( 2 ) . FROM I R O N , ALUMINUM, AND TITANIUM I N W E A K SOLL-TION
BY
MEANS
OF
EXCESS
(4) V O L A T I L I Z A T I O N O F I R O N F R O M A M I X T U R E O F
HC1 GAS-AS pointed out b y T r a v e r ~ -the , ~ volatilizatiofi of iron is attended with considerable difficulty and t h e danger of volatilizing zirconium increases as t h e temperature is raised above 650’ C. I t is also evident t h a t this treatment would be only a preliminary separation. OXIDES IN A C U R R E K T OF CHLORINE A N D
(5)
B A S K E R V I L L E ’ S ~ METHOD
OF
PRECIPITATING
T A N I U M AND ZIRCONIUM B Y BOILING W I T H
H2Sos
TIAND
HC1 S O L U T I O N O F T H E C H L O R I D E S - T h i s method seemed quite attractive b u t it was found t h a t : ( a ) The correct neutralization of t h e reduced acid solution of steel is a very difficult matter. Excess acidity causes low values, low acidity results in high contamination. ( b ) The complete elimination of aluminum, iron, and phosphorus presents difficulties. ( c ) I n addition t o t h e above drawbacks, t h e presence of chromium, cerium, and vanadium would undoubtedly cause inconvenience, and t h e determination of aluminum would require a special procedure. A VERY W E A K
(6)
1
3
4
J . Chem. SOC.,49 (1886), 149, 481. Private communication.
G a m chim. ita1 , 17 (1887), 479. F. S.Havens and A. F. Way, A m . J. Sci., 8 (1899), 212.
6 LOC.
cit.
a J . A m . Chem Soc., 16 (1894), 475.
F O R SEPARATION
MATTHEWS’~ METHOD
No. 6
12,
OF
ZIR-
CONIUM FROM I R O N BY TREATMENT OF DRY CHLORIDES WITH A N H Y D R O U S E T H E R SATURATED WITH HC1 GASAside from practical objections t o t h e method, such a s t h e specification of absolute ether saturated with hydrochloric acid gas, i t is not satisfactory since t h e precipitate will contain zirconium, titanium, aluminum, chromium, cerium, and possibly phosphorus a n d vanadium. It is obvious t h a t this would be b u t a s t a r t in t h e analysis of t h e steel. ( 7 ) REDUCTION OF IRON A S IN FERGUSON’S METHOD FOLLOWED B Y PHENYLHYDRAZINE PRECIPITATION^The following drawbacks are apparent: ( a ) Difficulty in removing all iron.‘ ( b ) The phenylhydrazine precipitate will contain in addition t o possible iron, all of t h e zirconium, titanium, aluminum, chromium, cerium, and phosphorus, probably all uranium, and considerable vanadium. (c) The analysis of t h e above complex mixture would require very careful analytical procedures. (8) SIMILAR T O ABOVE M E T H O D WITH FINAL SOLUTION
OF
PHENYLHYDRAZINE
PRECIPITATE
AND
PRE-
this procedure t h e following troubles were anticipated: ( a ) The necessity for removing all iron in t h e preliminary phenylhydrazine precipitations. ( b ) T h e question as t o whether phenylhydrazine would interfere in a cupferron precipitation. (c) The necessity of destroying organic matter before t h e precipitation of aluminum, and t h e interference of phosphorus in its determination; as well as t h e interference of other constituents such as chromium vanadium, cerium, and uranium. CIPITATION W I T H CUPFERRON-In
( 9 ) STROMEYER’S’ A P P L I C A T I O N O F CHANCEL’S4 M E T H O D O F S E P A R A T I N G I R O N FROM ALUMINUM AND ZIRCONIUM B Y P R E C I P I T A T I O N W I T H SODIUM THIOSULFATE IN W E A K HC1 S O L U T I O N - ~ ~ ~ ~statement ~ ~ ~ ’ S t~h a t i t is difficult t o separate all iron b y this method, a n d t h e fact t h a t t h e precipitates may be expected t o contain a variety of elements such as aluminum, chromium, cerium, etc., led us t o avoid this procedure. (IO) BERLIN'S^ METHOD IN WHICH MIXED OXIDES
OF
IRON
AND
CARBOXATE
AT
ZIRCONIUM WHITE
ARE
HEAT,
FUSED AND
WITH
THEN
SODIUM TREATED
HC1, WHICH DISSOLVES IRON A N D LEAVES ZIRU N A T T A C K E D - S Cstatement ~ ~ ~ ~ ~ ~concern’~~ ing t h e incompleteness of t h e separation and t h e partial solution of t h e zirconium, taken together with obvious difficulties on account of t h e large amount of iron t o b e dealt with, led us t o table this procedure. WITH
CONIUM
(11)
DITTRICH
AND
F R E U N D ’ S ~ METHOD
OF
SEPA-
R A T I N G Z I R C O N I U M A N D T I T A N I U M F R O M I R O N I N BIVAL E N T C O N D I T I O N B Y P R E C I P I T A T I O N W I T H S0DIUl-d AcETATE-It is obvious t h a t t h e sodium acetate preJ . A m Chem Soc., 20 (1898), 846. E. T. Allen, Ibid., 25 (1903), 421. 3 Awn Chem. Phavnt., 113 (1860), 127. 4 J. prakl. Chem., 74 ( l a s s ) , 471. 6 Ibid., 97 (1866), 337. 8 I b i d . , 58 (1853), 145. 7 Pogg. A n n , 59 (1843), 481. 8 Z . anovg Chem., 56 (1907), 348, 1 9
2
Vol.
I
June, 1 9 2 0
T H E JOURI\;TAL
OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
565
be qualitatively tested for in it. If molybdenum is present i t is more conveniently determined in a separate portion of steel.) The acid extract will contain some iron, and all of t h e zirconium, titanium, aluminum, nickel, chromium, etc. Gently boil off t h e ether in t h e acid extract, add the ( I 2 ) ELECTROLYSIS WITH MERCURY CATHODE OF matter recovered from t h e silica, oxidize ferrous iron DILUTE ACID SOLUTIONS OF THE S T E E L CONSTITUENTS~-By this method iron, cobalt, nickel, copper, and chro- with a little nitric acid, dilute t o 300 cc., cool, a n d premium can be deposited a n d separated from such ele- cipitate with 2 0 per cent sodium hydroxide solution, ments as aluminum, zirconium, titanium, uranium, adding I O cc. in excess. T h e sodium hydroxide solucerium, thorium, manganese, phosphorus, and vana- tion should be as pure as possible and free from cardium. Such a separation would obviously be most bonate. Filter, a n d save t h e filtrate. Dissolve t h e desirable in a plain zirconium steel; in this case a sub- precipitate in warm dilute I : I hydrochloric acid, sequent separation of zirconium from manganese and repeat the sodium hydroxide precipitation, filter, and phosphorus would be required. I n more complex combine t h e sodium hydroxide filtrates. Dissolve t h e alloys, the electrolysis would serve only as a prelimi- sodium hydroxide precipitate in warm dilute I : I nary Separation, and i t is doubtful whether t h e opera- hydrochloric acid a n d reserve t h e solution for subsetions incidental t o t h e preparation of t h e solution for quent analysis. It is advisable t o treat a s follows t h e filter or filters electrolysis a n d t h e electrolysis set-up would entail a n y less time and labor t h a n a n ether separation or a used above: Ignite in platinum, fuse with sodium carbonate, digest t h e cooled melt with hot water, wash separation b y Johnson’s method.2 the. residue, discard t h e filtrate and washings, dissolve IV-BUREAU O F STANDARDS METHOD t h e residue in hot I : I hydrochloric acid and add t o t h e ( A ) P R E L I M I N A R Y STATEMENT main acid solution. This precaution makes certain t h e T h e method developed a t t h e Bureau of Standards recovery of a n y zirconium held back on t h e filter a s permits t h e determination of silicon, aluminum, zirconium phosphate insoluble in acid. titanium, a n d zirconium in one portion of t h e steel, a n d DETERMINATION OF ALUMINUM. ( a ) In. the Absence provides for t h e following possible interfering elements: of Chromium and Uranium-Add a few drops of tungsten, chromium, uranium, cerium, manganese, methyl red t o t h e sodium hydroxide filtrate, neutralize phosphorus, vanadium, molybdenum, copper, nickel, with hydrochloric acid, a d d 4 cc. of concentrated and cobalt. hydrochloric acid per IOO cc. of solution, boil, make ( B ) METHOD barely alkaline with ammonium hydroxide, continue Dissolve 5 . 0 0 g. of t h e steel in 50 cc. of hydrochloric t h e boiling for 3 min., a n d set t h e beaker aside for I O acid (sp. gr. 1.2) with gentle warming a n d the addition min. If no precipitate settles out, t h e absence of of one cc. portions of nitric acid from time t o time t o aluminum is assured. If a white precipitate settles insure solution of the zirconium a n d titanium and also out, aluminum is indicated. This precipitate is always oxidation of t h e iron. contaminated b y phosphorus pentoxide a n d must be When solution is complete, evaporate t o dryness, purified as follows: Filter without washing, discard t h e t a k e up in I O cc. of hydrochloric acid (sp. gr. 1.2), filtrate and dissolve t h e precipitate in warm I : I again evaporate t o dryness, and finally bake a t a gentle hydrochloric acid. Dilute t h e solution t o 50 cc., make heat in order t o decompose nitrates. Cool, t a k e up in alkaline with ammonium hydroxide, neutralize with 5 0 cc. of I : I hydrochloric acid, a n d filter when t h e nitric acid and add 2 cc. in excess. Warm t o 50’ C., iron is completely in solution. Wash t h e residue with precipitate t h e phosphoric acid with molybdate hot 3 per cent hydrochloric acid. Save the filtrate a n d reagent in t h e usual manner, filter, and wash t h e washings. phosphomolybdate with a n ammonium acid sulfate Ignite the residue a n d paper in a platinum crucible, solution. Precipitate t h e aluminum in t h e filtrate a s cool, a n d weigh. Treat with I cc. of sulfuric acid ( I : I ) directed above, filter without washing, dissolve t h e a n d sufficient hydrofluoric acid, fume off in t h e usual precipitate in warm I : I hydrochloric acid, repremanner, ignite a n d weigh t o obtain silica, a n d calculate cipitate, filter, wash slightly with 2 per cent ammonium silicon. Fuse t h e slight residue left after t h e hydro- chloride solution and ignite in a platinum crucible. fluoric acid treatment with a small amount of potas- T h e ignited residue is usually contaminated by silica, sium pyrosulfate, dissolve in I O t o 2 0 cc. of 5 per cent therefore a sulfuric acid-hydrofluoric acid treatment sulfuric acid a n d a d d t h e solution t o t h e acid extract followed by ignition t o alumina over t h e blast lamp from t h e ether separation obtained as described below. should be performed. (The sodium hydroxide reagent Evaporate t h e filtrate a n d washings from t h e silica must be tested for substances precipitable by ammonia, determination t o a sirupy consistency, t a k e up in 40 a n d appropriate corrections must be made in t h e cc. of hydrochloric acid (sp. gr. 1.1) a n d extract with aluminum determination when these are present.) ether in t h e usual manner. (The ether extract will ( b ) I n Steels Containing Chromium-Proceed as contain most of the molybdenum, and this element may above until the filtrate from t h e molybdate precipita1 Wolcott Gibbs, A m . Ckem. J . , 13 (1891), 570; Edgar F. Smith, “Elec- ’ tion is obtained. Then make the solution ammoniacal, tro-Analysis,” 5th Ed., p 256; T. M. Drown and A. McKenna, Trans. A m . oxidize with a little bromine water, make just acid with Inst. Mtning Eng., 20 (1891), 242; J. R. Cain, THISJOURNAL, 3 (191 l ) , 476. I : 2 nitric acid, add ammonium hydroxide in slight 2 L O G . cit. cipitate will carry down in addition t o zirconium and titanium such elements as aluminum, chromium, phosphorus, a n d probably more or less vanadium, a n d t h a t t h e use of this reagent would therefore be b u t a preliminary step in t h e analysis.
566
T H E JOURUAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
excess, heat t o boiling, filter, dissolve t h e precipitate in dilute hydrochloric acid, and reprecipitate t h e aluminum hydroxide as directed above. (c) I n Steels Contaiiziizg Uranium-The only modification which is required is t h e substitution of ammonium carbonate for ammonium hydroxide as t h e final precipitant of t h e aluminum hydroxide. (d) I n Steels Contai?zing Vanadium-Alumina which is obtained by t h e above procedures from steels containing vanadium is contaminated by this element. When dealing with these steels proceed as follows: Fuse t h e weighed residue with pyrosulfate, extract t h e cooled melt with 5 per cent sulfuric acid, reduce t h e vanadium in a Jones reductor having ferric alum in t h e receiver, titrate t h e reduced solution with standard permanganate, calculate t h e vanadium as VzOs and subtract from t h e original weight.
Vol.
1 2 , No.
6
ferron precipitate. Then fuse thoroughly with sodium carbonate, cool, extract with water, filter, a n d determine t h e vanadium in t h e filtrate by adding sulfuric acid, reducing through a Jones reductor into a solution of ferric alum-phosphoric acid and then titrating with standard permanganate. Vanadium is thus reduced t o V202 and then oxidized t o VaOs. Calculate V 2 0 , and subtract from t h e combined oxides. Ignite in t h e original crucible t h e matter insoluble in water, fuse with potassium pyrosulfate a n d proceed as directed for titanium. 3-Tungsten does n o t interfere since i t is separated from zirconium and titanium b y t h e sodium hydroxide treatment, and from aluminum by t h e ammonium hydroxide precipitation. If tungsten is present in large amount i t may be found desirable t o fuse t h e nonvolatile residue from t h e silicon determination with sodium carbonate, extract with water, filter, dissolve D E T E R M I N A T I O N OF Z I R C O N I U M A N D TITANIUMt h e residue in hot I : I hydrochloric acid, and add t o Dilute t h e hydrochloric acid solution t o 2.50 cc., neutralize with ammonium hydroxide so as t o leave ap- t h e acid extract from t h e ether separation. 4-Uranium is partially carried down when present proximately j per cent (by volume) of hydroch1:ric acid, add 2 g. of tartaric acid, and treat with hydrogen in t h e quadrivalent condition, b u t not a t all in t h e sulfide until t h e iron has been reduced. Filter if t h e sexivalent state. If this element is suspected, boil out sulfide group is indicated. Make t h e hydrogen sulfide all hydrogen sulfide before t h e cupferron precipitation, solution ammoniacal and continue t h e addition of t h e oxidize with permanganate t o a faint pink, cool, and gas for j min, Filter carefully and wash with dilute proceed with t h e cupferron precipitation. ammonium sulfide-ammonium chloride solution. Filter j-Thorium and cerium interfere, b u t t h e y are not through a new filter if t h e presence of iron sulfide in t h e thrown down quantitatively. I n case these elements filtrate is indicated. Save t h e filtrate. are suspected, t h e peroxidized solution used for t h e (The sulfide precipitate consists of ferrous sulfide, titanium determination must be quantitatively prein addition t o t h e greater part of any nickel, cobalt served and reduced with a little sulfurous acid. The a n d manganese present in steel. It is preferable t o rare earths are t h e n separated b y Hillebrand’s method1 determine these in separate portions of t h e steel.) as follows: Precipitate t h e hydroxides with a n excess Neutralize t h e ammonium sulfide filtrate with sul- of potassium hydroxide, decant t h e liquid, wash with furic acid, add 3 0 cc. in excess and dilute with water t o water once or twice b y decantation and then slightly on 300 cc. Digest on t h e steam bath until sulfur and t h e filter. Wash t h e precipitate from t h e paper into sulfides have coagulated, filter, wash with I O O cc. of a small platinum dish, t r e a t with hydrofluoric acid, and I O per cent sulfuric acid, and coolthe filtrate in ice water. evaporate nearly t o dryness. Take up in 5 cc. of 5 per Add slowly a n d with stirring an excess of a cold 6 cent (by volume) hydrofluoric acid. If no precipitate per cent water solution of cupferron. (The presence is visible, rare earths are absent. If a precipitate is of a n excess is shown b y t h e appearance of a white present, collect it on a small filter held by a perforated cloud which disappears, instead of a permanent coagu- platinum or rubber cone a n d wash i t with from 5 t o I O lated precipitate.) After I O min. filter on paper, using cc. of t h e same acid. Wash t h e crude rare-earth a cone and very gentle suction, and wash t h e pre- fluorides into a small platinum dish, burn t h e paper cipitate thoroughly with cold I O per cent hydrochloric in platinum, add t h e ash t o t h e fluorides and evaporate acid. t o dryness with a little sulfuric acid. Dissolve t h e Carefully ignite in a tared platinum crucible, com- sulfates in dilute hydrochloric acid, precipitate t h e pleting t h e ignition over a blast lamp or large Meker rare-earth hydroxides by ammonia, filter, redissolve in burner, cool, and weigh t h e combined zirconium and hydrochloric acid, evaporate the- solution t o dryness, titanium oxides. a n d t r e a t t h e residue with 5 cc. of%oiling hot 5 per cent Fuse with potassium pyrosulfate, dissolve in jo cc.. oxalic acid. Filter after 1 5 min., collect t h e oxalates of I O per cent (by volume) sulfuric acid and determine on a small filter, wash with not more t h a n 20 cc. of titanium colorimetrically or volumetrically. Calculate cold 5 per cent oxalic acid, ignite and weigh as raretitanium oxide, subtract t h e weight found from t h a t earth oxides which are t o be deducted from t h e weight of t h e combined oxides, and calculate zirconium. of t h e cupferron precipitate. The above procedure does not give a n absolutely (C) N O T E S O N T H I S M E T H O D I-Phosphorus pentoxide contaminates t h e pre- quantitative recovery of t h e rare earths. Experiments cipitate t o so slight an extent t h a t it can be disregarded. indicate a recovery of approximately 85 per cent of t h e 2-Vanadium interferes no matter what its valency. rare earths present in residues containing I O O mg. of zirconia, z mg. of thoria, a n d 2 mg. of ceria. Attempts T h e interference is not quantitative. If present in t h e 1 U. S. Geol. Survey, Bulletin 700, 176. steel, proceed as usual through t h e weighing of t h e cup-
June,
1920
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
which were made t o omit t h e preliminary separation of t h e rare earths, as fluorides, were unsuccessful. 6-lnstead of t h e prescribed treatment for t h e removal of t h e bulk of t h e iron, Johnson’s1 method of fractional precipitation with ammonium hydroxide may be used. When using this method, it is recommended t h a t t h e I : I hydrochloric acid solution of t h e ammonium hydroxide precipitate should be further treated as given in t h e Bureau of Standards method beginning with “oxidize. . . . . . . . and precipitate with a 2 0 per cent sodium hydroxide solution.” I n Johnson’s procedure silicon must be determined i n a separate portion. 7-After considering t h e method and studying t h e notes, t h e reader might ask t h e question, “Why not use ammonium hydroxide instead of cupferron as t h e final precipitant?” T h e disadvantages of such a procedure are t h e following: ( a ) T h e necessity for destroying t h e tartaric acid which is in t h e solution, with attendant danger of contamination b y material resulting from t h e attack on glassware; ( b ) t h e co-precipitation of phosphorus and also chromium a n d uranium when t h e y are present The advantages of a n ammonia precipitation are: ( a ) It is a cheaper reagent; ( b ) t h e precipitation of cerium would be complete instead of partial. The following scheme of analysis is now being tested a t this Bureau: Zirconium, titanium, aluminum, cerium, chromium, vanadium, etc., are first separated from t h e bulk of t h e iron b y Johnson’s method, a n d t h e hydrochloric acid solution of this precipitate is t h e n treated with sodium hydroxide and sodium peroxide as described by Noyes, Bray and Spear.2 It is hoped t h a t this treatment will quantitatively precipitate iron, zirconium, titanium, and cerium, leaving such elements as aluminum, uranium, vanadium, chromium, tungsten, molybdenum, and phosphorus in solution. Iron, manganese, and t h e greater p a r t of t h e copper, nickel, and cobalt are next separated b y precipitation with ammonium sulfide in t h e presence of t a r t r a t e as recommended b y T h ~ r n t o n ,and ~ zirconium, titanium, (and cerium) are finally precipitated by ammonia after destroying t h e tartaric acid. T h e ignited a n d weighed precipitate is then treated for titanium a n d t h e rare earths as described in t h e Bureau method. (D)
CONFIRMATORY
EXPERIMEIiTS
Table I1 gives a summary of t h e d a t a obtained in t h e analysis of t h e Bureau of Standards acid-open-hearth TABLEI1 Zr Zr A1 A1 Ti Ti Ni V Cr Cu Pres. Pres. Pres. Pres. Added Found Added Found Added Found G . G . G. G. G. G. 0 . G . G . G. G. h-one None Kone None None None 0.0005 0.0009 0.0034 None None None None None None 0.0005 0.0009 0.0034 0.0100 0.0101 0.0100 0.01021 0.0101 0.00978 0.0005 0.0009 0.0034 0.0100 0.0094 0.0100 0.01021 0.0101 0.00973 0,0005 0.0009 0.0034 0 0500 0.0502 0.0476 0.0482* 0.0500 0.04933 0.0005 0.0009 0.0034 0,0005 0.0009 0.0004 0.0009 0.0500 0.0501 0.0476 0.04822 0.0500 0.04923 1 Colorimetrically. 2 Volumetrically after reduction in a Jones reductor and collection in ferric alum solution. ~~~~~. 3 T h e special treatment for vanadium (see Note 2) was not carried out. This furuishes an interesting light on t h e slightly higher values for titanium obtained both colorimetically and volumetrically and the correspondingly lower values for zirconium which resulted on account of the omission of this step. N 1 2 3 4 5 6
~
1
2
*
~~
~~~
cit. Technology Quarterly, 21 (1908). 35. A m . J . Sci., 37 (1914), 173. LOG.
567
steel Yo. 20a t o which definite amounts of standardized solutions were added. V-S
U M &I AR Y
This paper presents a critical review of published and theoretical methods for t h e determination of zirconium in steels, and gives a method for t h e determination of silicon, aluminum, titanium, and zirconium in steels containing other probable or possible alloying elements such as tungsten, chromium, vanadium, phosphorus, molybdenum, copper, nickel, cobalt, uranium, and cerium. The authors desire t o express their thanks t o Dr. W. F. Hillebrand for valuable suggestions and advice, and t o Mr. J. R. Eckman for help in experimental work. THE TITRATION OF AMMONIUM ACID FLUORIDE By Wallace S. Chase RES~ARCH LABORATORY, THE HARSHAW FULLER A N D GOODWINCu., CLEVELAND, OHIO Received December 13, 1919
Some time ago acidity estimation on ammonium acid fluoride was added t o t h e routine tests of t h e analytical laboratory. A fairly complete search of t h e literature failed t o reveal any method for this determination, b u t it was learned t h a t direct titration with standard sodium hydroxide in t h e presence of chipped ice, using methyl orange as a n indicator, was more or less successful. T h a t procedure was tried, b u t proved t o be entirely unsatisfactory, owing t o t h e indefiniteness of t h e end-point. Ordinarily t h e titration of a n acid salt of a strong mineral acid is easily accomplished. The case of ammonium acid fluoride is a n exception, owing t o t h e fact t h a t none of t h e common indicators, namely, phenolphthalein, methyl orange, litmus, lacmoid, methyl red, and cochineal, act satisfactorily. Phenolphthalein is eliminated because of t h e influence of ammonium salts, a n d t h e other five indicators are useless because of erratic end-points i n titrating hydrofluoric acid. It was evidently necessary for t h e titration of this material t h a t either ammonia or t h e fluorine be removed. The following method, based on precipitation of fluorine by calcium chloride a n d titration of t h e equivalent hydrochloric acid liberated, was consequently evolved. PROCEDURE
Weigh 1.3 t o 1.4 g. of material in a small weighing bottle (which is coated on t h e inside with paraffin t o about three-fourths of its depth), and transfer t o a 400cc. beaker \;-ith cold water, taking care t o keep t h e volume down t o about 1 2 j cc. The material dissolves rapidly, b u t solution is hastened b y stirring, and t h e fluoride is immediately precipitated by adding a solution consisting of j t o 6 g. of C. P. calcium chloride dissolved in about 7 5 cc. of water and neutralized (as is always necessary owing t o t h e CaO present) with dilute hydrochloric or sulfuric acid using methyl orange as an indicator. The mixture is stirred thoroughly for about a minute,
