Determination of Nonmetallic Inclusions in Plain Carbon and Manganese Steels Iodine and Nitric Acid Extraction Methods Twos. R. CUNNINGHAM AND R. J. PRICE Union Carbide and Carbon Research Laboratories, Inc., Long Island City, N. Y. IIIS method, using ferrous iodide solution for solution of the steel, has been developed from the procedure published by Eggertz:(S), The formation of insoluble iron compounds is one of the chief obstacles in this method when applied to the determination of oxides in steel. The authors have found that the addition of a certain amount of ammonium citrate to the solution of ferrous iodide eliminates this difficulty. I n addition, it has been found that the solubility of the oxides themselves is extremely small when the method is applied as described. Among the more recent investigators of iodine extraction methods are Westcott, Eckert, and Einert (8), who recommended the procedure for such inclusions as wrought iron slags, although no precautions were taken to prevent hydrolysis, and Willems (7) whose modified method resulted in the recovery of only 60 per cent of the manganese oxide.
DETERMINATION OF SiOz, MnO, FeO,
AND
AlzOs
The residue from the ferrous iodide extraction is fused with one gram (a sufficient amount) of sodium carbonate. The melt, after cooling, is transferred to a 150-cc. covered porcelain casserole, and dissolved in 20 cc. of hydrochloric acid (1to 1). Five cubic centimeters of 60 per cent perchloric acid are introduced and the solution is evaporated to strong fumes of perchloric acid to dehydrate silica. The residue is treated with 50 cc. of water and a few drops of sulfurous acid; the solution is then heated to boiling to expel sulfur dioxide, and filtered on a 9-cm. paper containing some ashless paper pulp. The paper and silica are washed well with hot water, ignited a t 1000" C., and weighed. The silica is then determined by volatilization with hydrofluoric and sulfuric acids in the usual manner. The filtrate from the silica is diluted to exactly 100 cc. with water and divided into two equal portions. To one portion, contained in a 300-cc. Erlenmeyer flask, 15 cc. of nitric acid (sp. gr. 1.42) are added and the manganese is determined by the bismuthate-arsenite method. The manganese found is calculated to MnO. To the other portion of the filtrate from the silica, contained n a 250-cc. beaker, 5 grams of ammonium chloride are added, and the solution heated to incipient boiling. Dilute filtered ammonium hydroxide (1 to 1) is added in faint excess (the pH value is held as near to 7 as possible), and the contents of the beaker are boiled for 30 seconds. The solution is filtered on a 9-cm. paper and bhe residue washed from eight to ten times with warm 2 per cent ammonium chloride solution. The filtrate is discarded. The precipitate is dissolved from the paper into the original 250-cc. beaker, with a jet of hot hydrochloric acid (1 to 1). The solution is nearly neutralized with ammonium hydroxide, 2 grams of ammonium chloride are added, and the contents of the beaker again heated to incipient boiling. The precipitation with ammonium hydroxide is then repeated, as described above. After filtering and washing with 2 per cent ammonium chloride solution, the paper and residue are transferred to a weighed platinum crucible provided with a tightly fitting cover, and ignited first a t a low temperature and then to constant weight a t 1 1 0 0 O C. The final heating should be done with the cover off or else some Fe30awill be formed. After cooling in a desiccator, the covered crucible and contents are weighed. The increase in weight represents Fe20a AlzOa. The combined oxides of iron and aluminum are fused with one gram of sodium carbonate and the melt, after cooling, is dissolved in dilute hydrochloric acid. After boiling the solution for a few minutes to remove carbon dioxide, the iron and aluminum are precipitated with ammonium hydroxide, filtered, dissolved in hydrochloric acid, and the iron determined by reduction with stannous chloride and titration with potassium permanganate. The iron found is calculated to Fez08 and this weight is deducted from the combined weight of Fez08 and Alz03, to give the weight of Al&. The weight of Fez03 found is calculated to FeO.
PREP.4RATION OF FERROUS IODIDE SOLUTION Five grams of plain carbon steel drillings with silicon content not over 0.03 per cent are transferred to a 300-cc. Erlenmeyer flask containing 25 cc. of cold water, 4 grams of ammonium citrate, and 30 grams of pure iodine. The flask and its contents are twirled in ice water until the steel has practically all dissolved. Thirty grams of additional iodine are introduced, and the shaking is continued until all iodine has dissolved, at which time the solution is filtered. The total volume of the filtrate and washings should not exceed 75 ec. This amount of ferrous iodide is used to treat 5 grams of drillings or a 5-gram solid piece of steel. Should the drillings or solid piece treated weigh more than 5 grams, the ferrous iodide should be increased proportionately.
SOLUTION O F THE SAMPLE
From 5 to 10 grams of the carefully prepared drillings or solid piece of steel are treated with from 75 to 150 cc. of ferrou8 iodide solution in a 300-cc. Erlenmeyer flask. The stoppered flask is placed in ice water and twirled continuously. The solution should not be allowed to become warm a t any time; therefore it is necessary that the agitation of the flask and its contents be continued until the sample has almost completely dissolved. The flask is then placed in a shaking machine (run a t a low speed) until the metal has dissolved completely, at which time the solution is immediately filtered on an 11-cm. filter paper of close texture containing a small amount of ashless paper pulp. The filter paper and residue are washed from eighteen to twenty times with cold 2 per cent ammonium citrate solution to remove ferrous iodide, followed by hot 2 per cent ammonium citrate to remove all iodine, and ignited in a platinum crucible first a t a low temperature and finally a t 1000° C. in an oxidizing atmosphere, cooled in a desiccator, and weighed. If the silicon content of the steel exceeds 0.25 per cent, the residue is washed several times with hot water to remove ammonium citrate, after which it is washed with approximately 50 cc. of 5 per cent potassium hydroxide, then thoroughly with hot water, and ignited.
+
27
ANALYTICAL EDITION
28
I n case the actual determination of aluminum is desired, the precipitate from the second ammonium hydroxide separation, described above, is dissolved in 20 cc. of hydrochloric acid (1 to 3))the solution cooled to 10" C., and some ashless paper pulp added. The iron is precipitated by the addition, drop by drop with constant stirring, of a cold freshly prepared 6 per cent solution of cupferron (ammonium nitrosophenylhydroxylamine, CGH~(NO)ONH~). The presence of an excess of the reagent may be detected by the fact that the addition of more cupferron gives a snow-white precipitate which quickly dissolves. The precipitate is filtered on a 9-em. paper and washed six to eight times with cold 2 per cent hydrochloric acid. The residue may be ignited and weighed as Fe203. To the filtrate, which contains the aluminum, 30 cc. of nitric acid (sp. gr. 1.42) are added and the solution boiled down to a volume of 15 cc. Five cubic centimeters of perchloric acid are introduced and the contents of the beaker evaporated to dense fumes of perchloric acid. After cooling, the cover glass and sides of the beaker are rinsed down with a jet of water, and the solution is again evaporated to fumes of perchloric acid. Fifty cubic centimeters of water are introduced and the aluminum is precipitated with ammonium hydroxide, as already described. After igniting in a tared platinum crucible, provided with a closely fitting cover, the residue is weighed as A1203. TABLEI Slag
Si02 FeO Fez01 MnO
1 2 FeOSios
%
%
%
%
%
33.55 53.40 6.23
28.96 2.58 63:i5 94.69
29.40 5.61 11.17 49.11 95.29
30.88 22.27 8.29 33.44 94.88
32.00 33.62 12.29 16.79 94.70
2.01 48.51
12.17 38.03
23.11 25.90
34.73 13.05
,..
93.18 F e (total) M n (total)
2 3 4 5 2 Mn0.- Fe0.Fe0.Fe0.Si02 31nO.SiOn MnO.Si0z MnO Si02
45.79
It will be noted that the most marked difference between the method as here described and the iodine methods formerly used consists in the addition of ammonium citrate (a neutral salt) and the low temperature maintained during the solution of the sample and the washing of the filter paper to remove ferrous iodide, It is essential to have the ammonium citrate present to prevent hydrolysis of iron. Samples analyzed in the absence of this salt give variable, erratic values for ferrous oxide, whereas, when the citrate is added, closely agreeing checks are obtained. The citrate also prevents the precipitation of ferric phosphate, thereby eliminating the necessity of testing for phosphorus. The temperature during solution of the steel is kept low further to insure the prevention of hydrolysis and especially to decrease the possibility of dissolving the inclusion particles. It may alfio be noted that the flask is agitated continuously during solution of the steel. Besides helping to keep the liquid cold, this prevents the formation of a film of carbon on the steel, which greatly retards the rate of solution. It may also be observed that the strength of the ferrous iodide solution is maintained within definite limits. Should the solution used be too weak, incomplete solution of carbides would ensue. Sulfides are decomposed by the ferrous iodide treatment, the sulfur being set free as elemental sulfur. Nitrides are also decomposed. Some so-called plain carbon steels contain small amounts of chromium carbide and in some cases vanadium carbide. These carbides are not broken up by the ferrous iodide treatment, causing plus errors in any calculation of iron oxide from total oxides. However, it has been found in practice that these carbides, when present, are in such small quantities that their effect on the result is so slight that it may safely be neglected.
Vol. 5 , No. 1
EXPERIMENTAL DATA Two grams of each of five 200-mesh slags, as shown in Table I, together with 5 grams of Armco iron drillings (on which a blank had been run), were treated as described. Analyses of the slags after the treatment, together with the percentage recovery of the total silicon dioxide, iron, and manganese are given in Table 11. TABLEI1 PERCENTAGE OF TOTAL ANALYSIS OF RESIDUE RECOVERED SiOa Fe Mn Si02 Fe Mn % % % % % % la 32.80 45.51 97.8 99.4 ... 2 27.93 1.96 47:?8 96.4 97.6 98.7 3 28.72 12.01 37.60 97.7 98.7 98.9 4 30.22 23.09 26.85 97.9 99.9 99.8 5 31.41 34.46 13.11 98.1 99.2 99.0+ To a mixture of slag 1 and Armoo iron drillings, 0.01 gram of pure Ah01 (finely powdered and ignited to l6OO0 C . ) waB added, and the whole treated by the ferrous iodide method. It was found that 0.0097 gram of AlmOs waa recovered. SLAG
.
Samples of steel containing 0.038 and 0.44 per cent sulfur, respectively, were treated with ferrous iodide and the residues were tested for sulfides with concentrated hydrochloric acid; no sulfides were detected. Fifty grams of steel were treated (in 10-gram portions) and the residues, after being centrifuged, were combined and analyzed for nitrogen; none was found. To a 5-gram sample of steel, 0.005 gram of phosphorus was added as ammonium phosphate, and the mixture treated with ferrous iodide; no phosphorus was found in the residue. I n order to test the accuracy and dependability of the method, a series of steel heats was made. Each heat was split, and one half was killed with aluminum according to the method of Herty, Freeman, and Lightner (4,while the other half was rapidly cooled. The aluminum-killed portions were analyzed for A1203 and the total oxygen was computed. The corresponding rapidly cooled portions were analyzed for slag inclusions by the ferrous iodide method and the total oxygen was calculated. Very close checks were obtained (2). DETERMINATION OF A1203BY ACID EXTRACTION This procedure is similar to that employed by Dickenson ( I ) , except that the strength of the nitric acid is increased and the liquid is not aerated. It is recommended that this method be used for the determination of as the time required for solution of the steel is much less than that for solution in ferrous iodide, or in 20 per cent hydrochloric acid, as described by Kichline (6). From 15 to 20 grams of the drillings or a solid piece of steel are treated with 600 to 800 cc. of 20 per cent nitric acid in a porcelain casserole. When all action has ceased the solution is filtered, with aid of gentle suction, on superimposed 11-em. filter papers of close texture, containing a small amount of ashless paper pulp. The papers and residue are washed with 5 per cent hydrochloric acid to remove iron, and ignited in a platinum crucible. The contents of the crucible are fused with one gram (a sufficient amount) of sodium carbonate, and the aluminum is determined by one of the methods previously described. A sample of steel containing a complex manganese-aluminum silicate gave a value of 0.007 per cent A1203 by both nitric acid and hydrochloric acid extraction. The ferrous iodide method, applied to the same sample, showed 0.0065 per cent &03. Another steel yielded a value of 0.075 per cent A1203by both the nitric acid extraction and the ferrous iodide treatment. To a sample of alumina-free steel, 0.01 gram of A1208 (finely powdered and ignited at 1600O C.) was added. After applying this nitric acid extraction, 0.0095 gram of AlzOs was recovered.
January 15, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
LITERATURE CITED (I) Dickinson, J.Iron Steel Inst. (London), 113,177 (1926). (2) Egan, Crafts, and K i n d . Paper to be presented before Iron and Steel Division, American Institute of Mining and Metallurgioal Engineers, February, 1933. ( 3 ) Eggertz, Polytech. J.,188,119 (1868).
29
(4) Herty, Freeman, and Lightner, Bur. Mines, Repts. Investigations 3166 (April, 1932). ( 5 ) Kichline, J. IND. ENO.CHEM.,7, 806 (1915). (6) Westoott, Eckert, and Einert, Ibid., 19,1285 (1927). (7) willems, Arch. Eisenhattenw., 1, 665-8 (1928). R ~ C E I V EOotober D 29, 1932.
Estimation of Gossypol in Cottonseed Meal A Modified Method J. 0. HALVERSON AND F. H. SMITH, Agricultural Experiment Station, Raleigh, N. C. OSSYPOL occurring in
tion of the small a m o u n t s of The Withers-Carruth method as modiJied by the ether-soluble gossypol rethe cotton seed is readily Schwartze and Alsberg for the estimation of maining in cottonseed meal, the soluble in ethyl ether. gossypol in cotton seed is not adequate for the results of which are presented in Carruth made use of this fact determination of gossypol in cottonseed meal. in his method of estimation (a). this paper. From this study The proposed method has overcome the objections the method was formulated for In the process of manufacture the estimation of gossypol. of cottonseed meal, the gossypol and consists in the removal of a part of the oil in The modifications introduced not expressed into the oil, but the meal by a preliminary extraction with are: a preliminary extraction of remaining in the meal, becomes petroleum ether, followed by thorough extraction the oil remaining in the meal; in a large part insoluble in ethyl of gossypol from the air-dried meal with U. S. P. the precipitation upon standing ether. I n order to estimate the ethyl ether and removal of the ether from the overnight and filtering off an small amounts of this remaining ether-soluble gossypol in the insoluble flocculent precipitate; extract by partial vacuum. The residual extract meal, there is need of a method the use of ethylene glycol as an is diluted with petroleum efher and allowed to which is expeditious and accuaid in precipitation of gossypol stand overnight. The material insoluble in rate, and which will avoid the as dianiline gossypol; and digespetroleum ether precipitates and is Jiltered off. tion on the steam bath in the difficulties of the present method Aniline and ethylene glycol are added, the latter of C a r r u t h as modified by presence of a high boiling point p e t r o l e u m ether, followed by Schwartze and Alsberg (6). aiding the precipitation on the steam bath of the constant shaking or s t a n d i n g But one p u b l i s h e d modifidianiline gossypol in the presence of a petroleum cation of the Carruth method has before the p r e c i p i t a t i o n of ether of high boiling point. After standing overbeen made, that of Schwartze dianiline gossypol is complete, night, precipitates of a satisfactory degree of and Alsberg. This consisted in when it is filtered off, dried, and purity are obtained. extracting the ground seed in weighed. a Soxhlet extraction t h i m b l e , METHOD IN DETAIL removing the ether, allowing the residue to stand overnight after the-addition of 8 to l0;olumes of petroleum ether, and PRELIMINARY EXTRACTION OF OIL' then filtering off the precipitated insoluble material that Transfer a charge of 75 grams of cottonseed meal, ground would otherwise contaminate the precipitate of dianiline gossypol. One cubic centimeter of aniline was then dis- to pass through a 40-mesh sieve, to a 500-cc. Erlenmeyer flask solved in the solution with shaking, and allowed to stand until with 100 cc. of petroleum ether (b. p. 30" to 80" C,). (Fracprecipitation occurred. After standing 3 to 7 days, this tions of ordinary gasoline distilling between 30' and 108" C. precipitate was filtered on a tared Gooch crucible, washed, have been used.) Shake vigorously for 5 minutes and dried a t 100" C., and weighed. The filtrate was further filter through a Biichner funnel. Remove thoroughly with a allowed to stand from a week to a month in order to small amount of petroleum ether any meal adhering to the determine whether precipitation was complete. If neces- Erlenmeyer flask. Carefully remove the petroleum ether sary, corrections were made for any subsequent precipitation. from the meal in the Biichner funnel. Transfer the meal The accuracy of this method is shown by a recovery of 90 to shallow pans, and allow to dry a t room temperature for per cent of 0.7 gram of gossypol from 25 cc. of oil. In order to several hours with occasional stirring in order to remove all obtain this degree of accuracy, the authors used a large the petroleum ether. After washing with petroleum ether and air-drying, examount of gossypol in comparison with the minute amounts present in meal, tract the charge thoroughly (approximately 72 hours) with The Carruth method, as modified by Schwartze and Als- U. S. P. ethyl ether to which 5 cc. of distilled water are added berg, is not sensitive enough to estimate the small amounts of in the receiving flask, using a Soxhlet extractor having an ether-soluble gossypol remaining in the meal because of inside diameter of 50 mm. (Anhydrous ether and moistureseveral factors. The excess oil in the oil-petroleum ether free samples of meal cannot be used as the gossypol does not mixture hinders precipitation of dianiline gossypol. There extract quantitatively.) After removing the thimbles, is not a complete elimination of the troublesome contaminat- recover the ether by distillation into the Soxhlet until 15 to ing insoluble precipitate (in petroleum ether) ; the length of 20 cc. of extract remain in the extraction flask. Remove the time required to precipitate aniline gossypol and the in1 Omit this step in the analysis of seed, t o prevent the precipitation of completeness of this precipitation are unsatisfactory. gossypol by the petroleum ether; however, the small amounts of gossypol A study has been made of the factors involved in the estima- present in the meal do not precipitate.
G
