T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
316
sodium hydroxide solution are mixed with 2 parts of PYro. I n cases where the small quantity of carbon monoxide given off is below the error of analysis, as when used in the Orsat apparatus, Solution 6 will be found suitable. BUREAUO F MINES WASHINGTON, D. C.
THE DETERMINATION OF URANIUM IN ALLOY STEELS AND FERRO-URANIUM By
G. I. KELLEY,3. B. MYERS AND C. B. ILLINGWORTH Received October 3, 1918
The recent use of uranium in alloy steels has made it desirable t o develop a convenient and reliable method for determining this element in the presence of any of the other elements now in common use in the manufacture of alloy steels. Uranium has been used in the manufacture of commercial high-speed steels where i t might be associated with chromium, molybdenum, vanadium, tungsten, and cobalt; and it has been used, experimentally a t least, in steels containing chromium and nickel. I n addition t o the elements named above, carbon. manganese, silicon, phosphorus, and sulfur are always present, and aluminum and titanium may be present in small amounts. The method as outlined below provides €or these possibilities. A 2 g. sample is dissolved in 7 5 cc. of I : I hydrochloric acid. After solution is complete the solution is oxidized by the dropwise addition of nitric acid. I n the case of samples where tungsten is present a n easily filterable product is obtained by diluting t o 300 cc. and boiling for 15 min. The tungstic oxide is then filtered out and washed, the filtrate and wash waters being returned t o the original beaker for evaporation t o dryness, followed by baking a t a moderate temperature. On dissolving the residue with 50 cc. of I : I hydrochloric acid and diluting with hot water, a solution is obtained from which the balance of the silica and the last traces of tungsten can be separated b y filtering. The two precipitates after washing are available for the determination of tungsten a n d silicon by the usual methods. Filtrates and wash waters from these precipitates are combined and evaporated t o a syrupy consistency in preparation for the extraction of most of the iron with ether. I n the absence of tungsten the original solution is evaporated t o dryness and baked with the object of removing silica. After the extraction of the iron, the aqueous layer is evaporated t o a small volume t o free i t from the excess of acid. It is then diluted t o a volume of 1 5 0 cc. with hot water, and a n excess of sodium carbonate in the form of a saturated solution is added. This solution IS boiled and, after settling, filtered, the precipitate being washed with hot water. The precipitate consists of the hydroxides of chromium, iron, manganese, cobalt, nickel, copper, and aluminum, if all of these elements are present, together with traces of silica, titanic oxide, phosphorus, and vanadium compounds. The filtrate contains uranium, molybdenum, vanadium, and traces of the elements which occur chiefly in the precipitates. Bulky precipitates should be dissolved in hydro-
Vol.
II,
No.
4
chloric acid and reprecipitated one or more times with sodium carbonate solution t o insure a complete separation of the uranium. The difficulties from this source are not as great as might be expected. All filtrates from the precipitate are cautiously acidified with sulfuric acid and boiled long enough t o insure the complete removal of all carbon dioxide. Ammonia free from carbonate is then added in slight excess. Boiling precipitates the uranium, much of the vanadium, and traces of impurities. The molybdenum is left in the filtrate. Steels contain only small amounts of phosphorus and the contamination of the uranium from this source is usually negligible. When, however, as may occur, the amount of phosphorus is large, i t may be necessary t o dissolve the precipitate in nitric acid, and after suitable oxidation, precipitate the phosphoric acid with ammonium molybdate. The phosphorus can then be removed as ammonium phosphomolybdate. The uranium and vanadium may be reprecipitated from this filtrate along with the manganese, if permanganate is used t o oxidize the phosphorus, by adding a few drops of sulfuric acid, a s m a l l amount of ammonium persulfate, and enough carbonate-free ammonium hydroxide t o give a n excess. The precipitate obtained by boiling the solution is in the condition corresponding t o the first uranium precipitate mentioned above. The impure uranium precipitate containing phosphorus in negligible amounts, o i free from it, is transferred to a beaker with a little water and solid ammonium carbonate added. On heating this solution under conditions and for a time calculated t o result in only a partial decomposition of the ammonium carbonate, the uranium and vanadium go into solution leaving the manganese, iron, and other impurities undissolved. The filtrate is acidified with sulfuric acid and boiled until i t is free from carbon dioxide, when a slight excess of carbonate-free ammonium hydroxide is added. This precipitates only the uranium and vanadium. I n common w;th other investigators we have not been successful in finding convenient and satisfactory procedures for separating these elements. The combined precipitates of uranium and vanadium are ignited at dull redness in a platinum crucible, allowing free access of air t o reoxidize any reduced material. The ignited residue is weighed as UsOs VzO6. I n general, only a small part of the vanadium is present in this precipitate, thus malting it unavailable for the vanadium determination. I t is necessary, however, t o determine the vanadium t o correct the weight of uranium oxide. This may be done b y almost any of the several known methods for determining vanadium. To this end we determine the vanadium after reduction with hydrochloric acid b y permanganate titration, and by oxidation with ammonium persulfate and silver nitrate, followed by electrometric titration. The latter method is the more certain and convenient, but the former gives entirely satisfactory results. For the purpose of either method the precipitate is dissolved in 50 cc. of concentrated hydrochloric acid and evaporated with 30 cc. of sulfuric acid (sp. gr. 1.58) until fumes appear. When
+
4
Apr., 1919
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
the titration is t o be completed with permanganate, t h e sulfuric acid solution is diluted t o 2 5 0 cc. with hot water and titrated a t 80' C. t o t h e first pink color. At the same time like quantities of sulfuric and hydrochloric acids are evaporated, diluted, and titrated in similar fashion to obtain a blank correction for the vanadium. When the titration is t o be made electrometrically, the sulfuric acid solution is diluted t o 2 5 0 CC:. with hot water, oxidized with silver nitrate and ammonium persulfate as described elsewhere' by one of US, and titrated with ferrous sulfate. The weight of variadlum so found is multiplied by 1.784 t o convert it into the corresponding weight of the oxide Vs05. This weight is subtracted from t h e weight of the resiVzO5. The corrected weight of the oxide due UaOs USOSis converted into t h e corresponding weight of uranium by multiplying by 0.8483 from which the percentage of uranium can be calculated. A solution of uranium was prepared by dissolving about 4.5 g. of uranium nitrate in one liter of water. This salt was made by the J. T. Baker Chemical Company and was described as containing less than 0.001 per cent of sulfur trioxide, and as being free from alkali metals, alkaline earth metals, uranous salts, and other foreign metals. We evaporated 50 cc. of this solution in a platinum dish and ignited the residue as described above. By this analysis we found 0.1340 g. of the oxide U308. I n another experiment we acidified 50 cc. of t h e solution with sulfuric acid, and added 0.05 g. aluminum, I g. ammonium phosphate, and 0 . 0 2 5 g. vanadium as ammonium vanadate. On carrying out the procedure described above, we found 0.1350 and 0.1343 g. of t h e oxide U308. Electrometric analysis of t h e uranium salt indicated less t h a n 0.1 mg. of vanadium in this amount of solution. Below we have given a few determinations of uranium in z samples of steel. One of these was a nickel-chromium steel in which the approximate respective percentages of manganese, nickel, and chromium were 0.35, 3.00, and 1.45. The other was a high-speed steel in which t h e approximate respective percentages of manganese, chromium, tungsten, vanadium, and cobalt were 0.25, 4.00, 14.00,2.00, and 5.00. T o both of these samples definite amounts of the uranium solution were added. The determinations appear below:
+
Per cent U Present Nickel-Chromium Steel.. ........... 5 . 6 9 High-speed S t e e l . . ................. 5 . 6 9
Per cent U Found 5.71 5.64 5.65 5.65
The determhation of uranium in ferro-uranium is similar t o the analysis of steel for this element. A I g. sample was dissolved in a small amount of concentrated nitric acid, and when solution was completed, hydrochloric acid was added cautiously t o the amount of 30 cc. The solution was then evaporated t o dryness with t h e object of separating silica. After t h e removal of silica, t h e procedure was identical with that in the case of steel. RESEARCH DEPARTMENT MSDVALE STEELAND ORDNANCE COMPANY NICETOWN, PHILADELPHIA 1
J. A m Chem SOC., 88 (1916), 350.
317
STUDIES ON MANGANATES AND PERMANGANATES-I THE COURSE O F THE REACTION BETWEEN MANGANESE DIOXIDE, POTASSIUM H Y D R O X I D E , AND OXYQEN, A N D THE MANUFACTURE OF P O T A S S I U M MANGANATE B y H. I. SCHLESINGER, R. D. MULLINIX AND S. Poposal Received September 23, 1918
Among the important chemicals which in t h e past have been imported a t so low a price t h a t American manufacturers had not, up t o the time of the European war, undertaken its production t o any large extent is potassium permanganate. The obvious need for the product and its extreme scarcity have, however, made its manufacture in this country a necessity, and a number of plants are now engaged in producing it. Some of them encountered certain difficulties when they began continuous operation and one of us was asked by the Bureau of hiIines t o investigate the matter. Out of this investigation a number of results of both scientific and practical interest have developed and of these the most important are reported in this paper. There are several methods for manufacturing the permanganate; t h e most widely used is apparently'the one in which potassium manganate is first prepared as an intermediary product by heating a mixture of potassium hydroxide and manganese dioxide in a current of air. The resulting mix is then extracted with water or a dilute solution of caustic potash and the solution of manganate thus obtained is converted into a solution of the permanganate. The methods employed for this latter step need not be discussed here as t h e research now t o be reported deals only with the first step. It is necessary, however, t o point out t h a t in this second step a large proportion of the caustic combined in the first is again liberated either in a form in which it can be directly utilized or in which i t can be used after suitable treatment, depending upon the process used for t h e second step. Furthermore, owing in part to the spontaneous decomposition of manganate and permanganate solutions, in part t o manganese dioxide precipitated out in the second step and in part t o the fact t h a t t h e first step never results in complete interaction of t h e components, there is always a relatively large amount of manganese dioxide left over from each treatment. It is therefore self-evident t h a t economical working of the process not only requires as high a yield as possible of t h e manganate in the first step, but t h a t it is also necessary t h a t the neutralization of the residual and recovered manganese dioxide and potassium hydroxide must be highly successful. Difficulties have apparently been encountered in both of these phases of t h e process and we have therefore made a study of the factors which influence their successful carrying out. The conversion of manganese dioxide into potassium manganate by heating it in a current of air with potassium hydroxide has been extensively investigated. The most recent and apparently t h e most thorough of these investigations are those of Askenasy and 1 This paper is taken from material presented to the faculty of the Univeisity of Chicago b y R. D. Mullinix and b y S. Popoff in part fulfillment of the requirements for the degree of Doctor of Philosophy.
