January 15, 1932
INDUSTRIAL AND ENGINEERING CHEMISTRY
creased from 400" to 1100" C. The extracts from samples ignited a t 1000" and 1100" C. filtered very rapidly and the insoluble residues had practically no colloidal and sticky properties. A comprehensive investigation of the constitution and properties of tricalcium phosphate and the complex calcium phosphates is now being made in the Fertilizer Technology Division of the Bureau of Chemistry and Soils. ACKNOWLEDGMENT The authors wish to express thanks to E. F. Snyder of the Soils Fertility Division for making the potentiometric pH measurements on the citrate solutions used in t,he determination of citrate-insoluble phosphoric acid. LITERATURE CITED (1) (2) (3) (4) (6)
Assocn. Official Agr. Chem., Methods, p. 4, 1925. Barill6, J . pharm. chim., [6], 27, 437 (1908). Bassett, J . Chem. Soc., 111, 620 (1917). Buch, 2. anorg. Chem., 52, 326 (1907). Dircks and Werenskiold, Landw. Vers.-Sta., 34, 426 (1887).
31
Erlenmeyer and Anta, Ber., 14, 1253 (1881). Fresenius, Neubauer, and Luck, 2. anal. Chem., 10, 149 (1871). Grupe and Tollens, Ber., 13, 1267 (1880). Grupe and Tollens, Ibid., 14, 754 (1881). Haskins, J . Assocn. Oficial Agr. Chem., 4, 64 (1920); 5, 97 (1921); 5, 460 (1922). Herzfeld and Feuerlein, 2.anal. Chem., 20, 191 (1881). Jacob, Beeson, Rader, and Ross, S. Assocn. O$ciaZ Agr. Chem., 14, 263 (1931). Jacob, Hill, Ross, and Rader, IND. ENG.CHIN., 22, 1392 (1930). Jacob and Reynolds, Ibid., 20, 1204 (1928). Keenen, Ibid., 22, 1378 (1930). Konig, 2. anal. Chem., 20, 49 (1881). Lorah, Tartar, and Wood. J. Am. Chem. Soc., 51, 1097 (1929). Mellor, "A Comprehensive Treatise on Inorganic and Theoretical Chemistry," Vol. 111, p. 876, Longmans, 1923. Robinson, Michigan Agr. Expt. Sta., Bull. 46 (1919). Robinson, J. Assocn. Oficial Agr. Chem., 5, 92 (1921); 5 , 443 (1922). Ross, Merr, and Jacob, IND.
[email protected]., 21, 286 (1929). Warrington, J . Chem. Soc. (London), 19, 296 (1866); 26, 983 (1873). Zulkowski and Cedivoda, Chem. Ind., 26, 1, 27 (1903).
RECEIVBDMay 20, 1931. Presented before the Divieion of Fertilizer Chemistry at the 82nd Meeting of the American Chemical Society, Buffalo, N. Y.,August 31 to September 4, 1931.
Analysis of Beryllium Minerals FRANKLIN G. HILLS,Experimental Plant, Colorado School of Mines, Golden, Colo. LTHOUGH beryllium was discovered by Vauquelin in 1798, neither the metal, its minerals, nor its compounds have found any use in industry or the arts until quite recently. However, it has attracted considerable scientific interest since its discovery, Questions regarding its physical and chemical properties, its compounds, and methods of separation have received much attention and the answers have been found only after much study. I n making beryllium analyses the preliminary work offers no difficulties. It consists of a sodium carbonate fusion and the separation of silica in the usual way, then precipitation of the hydroxides with ammonia. This precipitate will carry the beryllium as hydroxide, together with iron, alumina, etc. As beryllium hydroxide is appreciably soluble in water, all washing should be done with a 2 per cent solution of ammonium nitrate. I n analyzing phosphate minerals, phosphorus must be separated as ammonium phosphomolybdate before proceeding with the other separations. The solution of the hydroxides in hydrochloric acid may be treated with hydrogen sulfide if second-group metals are present before proceeding with the other separations, but this is probably never necessary in ordinary mineral analysis. I n the author's work on the minerals mentioned above, three methods for the separation of aluminum and iron were used, beryllium in all cases being finally precipitated as the hydroxide with ammonia, and weighed as beryllium oxide after ignition. METHOD OF BERYLLIUM DEVELOPING CORPORATION H. S. Cooper, of the Beryllium Development Corporation of Cleveland, Ohio, reported (in a private communication to the author) a method which consists briefly in igniting the mixed hydroxides, fusing with sodium carbonate, leaching the melt with water, filtering, and then repeating the ignition, fusion, and leaching. Generally this second fusion and leaching will remove the last of the alumina, but with minerals high in
alumina a third fusion may be necessary. The last residue is ignited and fused with potassium pyrosulfate and dissolved in water. This should give a clear solution, except perhaps for a little silica which is removed by filtration. From this solution the hydroxides of iron and beryllium are precipitated with ammonia and collected on a filter, dissolved in dilute hydrochloric acid, and again precipitated with ammonia. The solution and re-precipitation are necessary to free the precipitate from alkali salts, which are readily adsorbed by beryllium hydroxide. The precipitate is ignited and weighed as beryllium oxide and ferric oxide. The precipitate is then dissolved in hydrochloric acid, the iron determined, and beryllium oxide found by difference. This method is obviously open to the criticism that obtaining the beryllium percentage by difference throws all the errors on the beryllium. Still it is a very satisfactory technical scheme. Another objection is that the method as outlined takes no account of manganese, which is a common constituent of beryllium minerals. If neglected, it is very largely carried through all the operations and will be reported as beryllium oxide. Manganese may be separated as follows: After making the bisulfate fusion, dissolving in water, and precipitating the hydroxides with ammonia, filter and dissolve the hydroxide precipitate with dilute nitric acid back into the beaker in which the precipitation was made. Evaporate to a small volume, but not to dryness, add 10 cc. of concentrated nitric acid, and precipitate the manganese with potassium chlorate. Filter out this precipitate and from the filtrate separate the iron and beryllium with ammonia as described above. This separation for manganese is never quite complete, so that traces of manganese will still be found with the beryllium. This small amount can be determined colorimetrically and deducted if necessary. With small amounts of manganese, oxidation sometimes goes to the permanganate condition.
32
Vol. 4, No. 1
ANALYTICAL EDITION
precipitation is necessary, and this results in a large volume of solution from which to separate beryllium. Here again manganese is not completely precipitated. For this reason it has been found more satisfactory to combine the 8-hydroxyquinoline separation with the Parsons method. That is, after making the bicarbonate precipitations, separating the iron, and acidifying the atrate, to the slightly acid solution is added an excess of a 2.5 per cent solution of 8-hydroxyquinoline in acetic acid, followed by 20 or 25 cc. of saturated ammonium acetate solution. The precipitate is allowed to settle, filtered, and washed with cold water. To the filtrate, a slight excess of ammonia is added, the mixture boiled, filtered, the precipitate washed with 2 per cent ammonium nitrate solution, ignited, and weighed as 6.3 (1). As beryllium hydroxide resembles aluminum hydroxide in beryllium oxide. If manganese is present in the ore, more or less will be found its behavior with ammonia, it is perhaps possible that manganese may be separated from beryllium in this way, but in with the beryllium oxide, This can be determined colorithis laboratory the separation has never been quite complete. metrically and deducted or, if too much is present for a colorimetric determination, it should be precipitated from a nitric acid solution with potassium chlorate. PARSONS’ METHOD(3) This procedure gives the best direct determination for I n this method the mixed hydroxides obtained in the usual beryllium for technical purposes. manner are dissolved in dilute hydrochloric acid and the soluThe accurate determination of small percentages of beryltion nearly neutralized by the careful addition of ammonia. lium is a difficult problem. If a large quantity of the maTo the slightly acid solution 10 grams of sodium bicarbonate terial is used, say 5 grams, the removal of the large amount of are added, the solution diluted with water to 100 cc., brought silica is troublesome. Besides, this usually means the quickly to the boiling point, and boiled for 30 seconds. The presence of a relatively large amount of alumina, which adds precipitate is filtered and washed with a warm 10 per cent to the difficulties. solution of sodium bicarbonate. The precipitate is dissolved There are few, if any, really distinctive qualitative tests for in warm dilute hydrochloric acid, nearly peutralized with either aluminum or beryllium, hence it is not possible to test ammonia, and the precipitation repeated with sodium bi- qualitatively for complete separations during the analysis. carbonate, It is filtered and washed as before. To the Kolthoff claims that as little as 0.05 mg. of beryllium combined filtrates 5 to 10 cc. of colorless ammonium sulfide per liter can be detected with curcumin. Curcumin is adare added, the mixture is stirred well and allowed to stand sorbed by beryllium hydroxide, giving a reddish color to the cold until the iron precipitate coagulates and settles, then it is precipitate. Iron and aluminum both interfere, but it is filtered and washed. claimed that the addition of sodium fluoride to the solution The filtrate is made slightly acid by the careful addition of will overcome their influence. hydrochloric acid, the carbon dioxide boiled off , ammonia Working with a proof solution fairly good results with this added until slightly alkaline, and the mixture boiled. Beryl- reagent were obtained but, working with minerals, results lium is precipitated as beryllium hydroxide. This is collected were very poor on account of the color fading rapidly. on a filter, washed with 2 per cent ammonium nitrate soluIt is quite possible that the poor results are due to faulty tion, ignited, and weighed as beryllium oxide. technic, but so far the difficulty has not been located. When working on proof material, this method always gives The retention of beryllium in the silica no doubt needs results somewhat high, owing to incomplete separation of attention. We know that silica retains a little alumina, which alumina together with manganese if this is present. With is recovered after volatilizing the silica with hydrofluoric acid. the small amount left with the beryllium, manganese is best It seems probable that a little beryllium is also retained and in determined colorimetrically and deducted from the final a very careful analysis this should receive attention. weight. The following tabulation shows a comparison of results The alumina left with the beryllium can be separated by obtained on minerals using different methods, and also rethe use of 8-hydroxyquinoline. covery on proof material: 8-HYDROXYQUINOLINE METHOD BBRYLLITJM CORP. PARSONS
and this has been overcome by pouring the solution through the filter paper several times, thereby reducing permanganate to manganese dioxide. It is claimed that when precipitating alumina with ammonia the precipitate can be kept free from manganese by careful regulation of the alkalinity, Hillebrand and Lundell (1) recommend the use of a few drops of methyl red (0.02 per cent alcoholic solution) for an indicator and the addition of dilute ammonia drop by drop until the color changes to a distinct yellow, then boiling the solution for not more than 2 minutes. The solution should contain a t least 5 grams of ammonium chloride for each 200 cc. of solution. Aluminum hydroxide is completely precipitated between pH 6.5 and 7.5. The transition range of methyl red is given as pH 4.2 to
The separation of aluminum from beryllium by the use of 8-hydroxyquinoline is described in an article by Lundell and Knowles (g), From a solution slightly acid with acetic acid, 8-hydroxyquinoline precipitates aluminum completely; leaving beryllium in solution. After removal of the aluminum by filtration, beryllium is precipitated as the hydroxide by careful addition of ammonia, after which it is filtered, ignited, and weighed. This is probably the sharpest separation available for these two elements. The only objection is that the aluminum precipitate with 8-hydroxyquinoline is very bulky. I n the application of this method to ores which are usually fairly high in alumina, a precipitate is obtained which is somewhat troublesome to handle. As iron in the ferric condition accompanies this precipitate, the bulk is increased still more. With such large precipitates a t least one re-solution and re-
MBTHOD
Mn Mn not separated separated Standard pulp 7.8% Be0 Proof solution 0.077% Be0 Beryl specimen
8.3
7.7
+
QUINO-
QUINO-
LINB
LINE
7.83
8.00 8.10 0.07
0.081
0.077
0.075
12.6
12.6 12.8
LITERATURE CITED (1) Hillebrand and Lundell, “Applied Inorganio Analysis,” Wiley, 1929.
(2) Lundell and Knowles, Bur. Standards S.Research, 3, 91-6 (1929). (3) Parsons, “The Chemistry and Literature of Beryllium,” Chemical Publishing Co., 1909. REC~IVBD June 25, 1931. Presented before the Colorado Seotion of the American Chemioal Society, Deoember 20, 1930.
