Rapid Chemical Analysis of Refractory Chrome Ores and Chrome-Bearing Refractories CALVIN S. RICHARDS and EVERETT C. BOYMAN' Kaiser Refractories Research Department, Milpitas, Calif.
b Rapid methods for the analysis of the major constituents of refractory grade chrome ores and chrome-bearing basic refractory materials are given. The sample is fused with a mixture of sodium carbonate and sodium borate in a platinum crucible. After solution of the melt with dilute sulfuric acid, aliquots are taken for the determination of silica, iron, alumina, and chromium. Spectrophotometric techniques are used to determine silica using the molybdenum blue method; iron is determined with orthophenanthroline; sodium alizarin sulfonate is used for alumina; and the chromium determination is made using diphenylcarbohydrazide. A separate sample is fused with sodium peroxide for the determination of calcium by flame photometry and magnesium is titrated with disodium dihydrogen 1,Z-diaminocyclohexane N,N,N',N'-tetraacetate. Results obtained compare favorably with conventional methods for these materials.
A
exploration program was begun in 1958. As samples began to come in from all parts of the world for chemical analysis, it quickly became apparent that standard met'hods ( 1 ) were far too slow and tedious. Therefore, an analytical program was set up to find more rapid means of analysis using absorption and emission spectrophotometric t'echniques where possible. Up until this time, a number of rapid schemes for analysis of silicate materials (5, 11, 15) had been presented. However, it' was not until lat'er in 1959 that, Dinnin ( 6 )published a Geological Survey bulletin on the rapid analysis of chrome ores. As would be expected there are similarities in some areas between Dinnin's work and the work presented here. Severtheless, it, is believed that, this paper gives a unique system of for the major constituents in chrome materials that is faster and just' as accurate as any previously found in the literature. The first step in the n w system of analysis was t,o find a flux that would REFRACTORY CHROME ORE
Deceased. 1790
ANALYTICAL CHEMISTRY
be suitable for all refractory grade as first observed by Goetz and Debchrome ores. The three principal brecht ( 9 ) in the titration of lead. fluxes tried were sodium hydroxide, With the procedures given, a chrome sodium peroxide, and sodium carore sample can be analyzed for silica, bonate-sodium borate. The most efiron, alumina, chromium, calcium, and fective flus was found to be equal magnesium in less than a day. Silica, parts of anhydrous sodium carbonate iron, and chromium can be determined and anhydrous sodium borate as sugin 3 hours. gested by Hazel (10). Hundreds of chrome ore samples from the world EXPERIMENTAL over have been fused successfully with Apparatus. All absorbance measthis universal flux. urements were made with a Beckman After fusion the melt is brought into DU spectrophotometer. Model solution with dilute sulfuric acid, and Flame determinations were made with the sample solution is transferred the same spectrophotometer and a quantitatively to a volumetric flask. Beckman spectral energy recording Aliquots of this solution are used for attachment (SERA) attached to a the determination of silica, iron, alustrip chart recorder. mina, and chromium. Preparation of Sample for Spectrophotometric Analysis. Fuse 0.2 gram Silica is determined using the molybdenum blue method of Bunting (4). of minus 200 mesh material with 1.5 grams of anhydrous sodium borate The yellow silicomolybdate is reduced and 1.5 grams of anhydrous sodium to molybdenum blue using a l-aminocarbonate in a covered platinum 2-napht'hol-4-sulfonic acid (ASS) recrucible for 50 minutes a t 1000° C. agent. The determination of total -4fter fusion is complete, place the iron is made using the 1,lO-phencrucible and lid in a 250-ml. beaker anthroline procedure described by Forwith a stirring rod. Add 60 ml. of 2-4' tune and Mellon (8). Again ASS is H2S04, cover with a watch glass, and boil gently to solution. Rinse the used as the reductant. The alumina crucible and cover x i t h water and transdetermination is made using sodium fer the solution to a 200-ml. volumetric alizarin sulfonate (alizarin red-S) and flask. Cool and dilute with water to is based on the work of Parker and 200 ml. at 20' C. The sample is now Goddard (12). As suggested by Silverready for analysis. man and Haivley ( 1 7 ) , acetone and heat are used t o increase the rate of SILICA DETERMINATION color development. Chromium is determined with diphenylcarbohydraside Reagents. ~ ~ M h l O ~ I U 11hOLYBDATE l the use of which has been carefully SOLUTION.Dissolve 15.0 grams of evaluated by Sandell (13). Silver ammonium molybdate in 100 ml. of peroxide functions both as a catalyst water. h d d 20 ml. of 1 8 5 sulfuric and an oxidizing agent. Slightly acidic acid by pipet, cool, and make to 200 ml. in a volumetric flask. Store in a 100% acetone solutions of the diphenylpolyethylene bottle. carbohydrazide reagent showed the best 1 - AMSO - 2 - XAPHTHOL - 4 - SULstability as reported by Urone (18). FOSIC .\CID (.\El). Dissolve 1.75 The determination of calcium is made grams of anhydrous sodium sulfite in by flame photonietry using a modificaabout 50 ml. of water. Add 0.375 tion of a method developed by Boyman gram of l-amino-2-naphthol-4-sulfonic which was published in a Beckman acid and stir to dissolve. Dissolve 22.5 application data sheet (W). ,4fter grams of anhydrous sodium bisulfite in removal of chrome, iron, and alumina, about 150 ml. of water. .1dd to the above and dilute to 250 ml. with water is titrated complexmagnesium in a volumetric flask. Store in a polyometrically with disodium dihydrogen lohesane LV,*V,L\7'!-l-'-ethylene bottle. Make fresh every week. tetraacetate (IICyT.1) using ErioProcedure. Pipet an aliquot not chrome I%lack T as the indicator acexceeding 50 ml. and containing about (14). cording to dehwarzenbach 0.2 mg. of SiOs into a 100-ml. voluDCyTA is used instead of EDT.\ metric flask. Add 1 drop of phenolbecause control of pH is less critical phthalein indicator solution. Make and sharper end points are obtained just alkaline by adding 2 5 YaOH
dropwise. Rinse the neck of the flask with water. Slowly add 6 N H 2 S 0 4dropwise until just acid. Add exactly 2 more drops and mix. Dilute to 50 ml. with water and mix. .idd 1 ml. of ammonium molybdate by pipet and mix. Let stand for 10 minutes. Add 5 ml. of tartaric acid solution by pipet and mix. Add 2 ml. of ANS by pipet and mix. Dilute to 100 ml. with water a t 20" C. and let stand for 30 minutes. Read the absorbance against a water blank a t 700 m p using the red tube and a slit width of 0.03 mm. Multiply reading by absorbance factor to obtain milligrams of' silica. Determination of Absorbance Factor. STANDARD SILICASOLUTIOK. A stock solution is prepmaredby dissolving 1.25 grams of sodium metasilicate (NasSi03.9HzO) in water and diluting to 250 ml. This solution is standardized gravimetrically using a perchloric acid dehydration. A solution is prepared by dilution to give 1 ml. = 0.01 mg. of SiOz and is stored in a polyethylene bottle. Pipet 20 ml. of dilute standard (1 ml. = 0.01 mg. SiOJ into each of three 100-ml. volumetric flasks to give 0.2 mg. of SiOz each. Follow procedure for silica determination. The absorbance factor is equal 'to milligrams of silica divided by the average absorbance.
procedure for iron determination. The absorbance factor is equal to milligrams of iron divided by the average absorbance. ALUMINA DETERMINATION
Reagents. STOCKSOLUTIONA. Dissolve 700 grams of sodium acetate with water, add 300 ml. of glacial acetic acid, and make to 2000 ml. with water in a volumetric flask. STOCK SOLUTION B. Dissolve 2.5 grams of alizarin red-S with 50 ml. of water and 10 ml. of 1S H2S04. Heat gently with stirring on a combination magnetic stirrer hot plate to solution of s o h b l e portion. Transfer to a 500-ml. volumetric flask, cool, and make to volume with water. Let stand for a few days and then filter through dry Whatman S o . 40 paper with a dry funnel into a dry storage flask. CALCIUM CHLORIDESOLUTION. Dissolve 7.0 grams of calcium carbonate with about 25 ml. of 6LV HC1. .Ifter boiling, cool, and make to volume in a 500-ml. flask. FERROUS SULFATE SOLUTION. Dissolve 3.5 grams of ferrous sulfate (FeSO4.7Hz0)with water, add 10 ml. of 61%' HzS04and make to volume in a 2000-ml. volumetric flask. No. 1 REAGENT.Pipet 20 ml. of 80% mercaptoacetic acid into a 500-ml. volumetric flask. Add by pipet 50 ml. IRON DETERMINATION of 2 N H a 0 4 , 50 ml. of CaCh solution, and 50 ml. of ferrous sulfate solution to the flask. Make to volume with Reagents. AKS. 'This is the same water and mix. reagent used for silica determination S o . 2 REAGEKT.Pipet 200 ml. of and is prepared identically. ORTHOPHENANTHROLINE SOLUTION. stock solution A into a 1000-ml. volumetric flask and add 400 ml. of water. Dissolve 4.00 grams of l,l0-orthophenAdd 50 ml. of stock solut'ion B by pipet anthroline with ethyl stlcohol and make plus 250 ml. of acetone. Mix and make to 1000 ml. in a volumetric flask with to volume with water. ethyl alcohol. Procedure. Pipet 20 ml. of sample AMMONIUMACETATE:BUFFER. Dissolution into a tall 200-ml. beaker. solve 460 grams of ammonium acetate Add 10 ml. of concentrated perin water and dilute to .LOO0 ml. chloric acid and t'ake t o fumes. Add Procedure. Pipet a n aliquot not a t least three 10- to 20-mg. increments exceeding 50 ml. and containing about of sodium chloride to volatilize the 0.2 mg. of Fe203into a 100-ml. voluchromium as chromyl chloride. Allow metric flask. Neutralize using 2 N the chromium to reoxidize between N a O H and phenolphthalein indicator. additions of sodium chloride. Cool, Add 6.V H&Ol dropwise until just dissolve with water, and transfer to a acid. Add 4 ml. of 61%' H2S04 a n d 1000-ml. volumetric flask. Then an mix. Add 2 ,ml. of ANS reductant aliquot not exceeding 50 ml. and conand mix. Make to yolume of about taining about 0.1 milligram of Ala03 60 mi. with water and mix. Add 2 is pipett'ed int,o a 100-ml. volumetric ml. of orthophenantliroline solution flask. Neutralize as before using 2N by pipet and mix. Dilute to about 85 NaOH and phenolphthalein indicator. ml. with water and mix. Add 10 ml. Add 6 N Has04 dropwise until just of ammonium acetate buffer, make to acid. Make to 60 ml. with hot water 100 ml. with water, and mix. Read and heat to just below boiling. Remove the absorbance against a reagent blank from the hot plate, immediately add 10 at 510 mp using the blue tube and a ml. of reagent No. 1 by pipet, and swirl slit width of 0.025 mm. Multiply reading by absorbance factor to obtain milliduring the addition. Add 20 ml. of grams of iron. reagent No. 2 by pipet while swirling Determination of A.bsorbance Facthe flask. Stopper and let stand for IRON/SOLUTION. Distor. STANDARD 30 minutes. Cool in a cooling bath to 20" C., make to volume with water, solve 0.3497 gram of 100.0% electrolytic iron with 50 rnl. of 12.47 HC1 and mix. Read the absorbance against and make t o 1000 ml. in a volumetric a reagent blank a t 500 mp using the blue flask. Pipet 20 ml. into a 1000-ml. tube and a slit width of 0.02 mni. volumetric flask a n d make to mark. Multiply 1,eading by absorbance factor (1 ml. = 0.01 nig. Fei03). to obtain milligrams of alumina. Pipet three 20-ml. (0.2 mg. Fez03) Determination of Absorbance Facaliquots of standard iron solution into ALUMINASOLUTION. tor. STANDARD 100-ml. volumetric flasks. Follow the Dissolve 0.5412 grams of clean X I
wire (99.698%) with 30 ml. of 6 N H2S04and 5 ml. of 12;V H C l in a 500ml. volumetric flask and make to volume with water. Dilute to obtain a final solution containing 0.006 mg. per ml. of '11203 Pipet three 15-ml. (0.09 mg.) aliquots of standard alumina solution into 100ml. volumetric flasks. Follow the procedure for alumina determination. The absorbance factor is equal to milligrams of alumina divided by the average absorbance. CHROMIUM DETERMINATION
Reagents. 1,5 - Diphenylcarbohydrazide. Dissolve 0.5 gram of diphenylcarbohydrazide with acetone and make to volume in a 100-ml. volumetric flask with acetone. Make fresh daily. Procedure. d n aliquot not exceeding 50 ml. and containing about 0.06 mg. of Crz03 is pipetted into a 100ml. volumetric flask. Add 5 ml. of 6 N H2SOl, dilute to approximately 50 ml. with hot water, and mix. Add approximately 20 mg. of silver peroxide. Heat gently to solution and avoid boiling. Dilute to about 95 ml. with water, stopper, and cool to room temperature in a cooling bath. Add 2 ml. of diphenylcarbohydrazide by pipet while swirling the flask. Make to volume with water and mix. Read at once a t 540 mp using the blue tube and a slit width of 0.02 mm. Use water for the reference blank. Multiply reading by absorbance factor to obtain milligrams of chromium. Determination of A b s o r b a n c e Factor. STANDARD CHROMIUM SOLUTION. Dissolve 9.807 grams of dried primary standard KzCrzO, with water and make to 2000 ml. in a volumetric flask. Dilute to obtain a final solution containing 0.004 mg. of Cr203per ml. Pipet three 15-ml. (0.06 mg.) aliquots of standard chromium solution into 100-ml. volumetric flasks. Follow the procedure for chromium determination. The absorbance factor is equal to milligrams of chromium divided by the average absorbance. CALCIUM DETERMINATION
Reagents. SODIUMPEROXIDE. Minus 40 mesh reagent grade. XaOH-Na2COs REAGENT. Dissolve 100 grams of S a O H and 200 grams of anhydrous Na2C03 with water, cool, and make to 2000 ml. in a volumetric flask. Store in a polyethylene bottle.
CALCIUMCARBONATE STOCKSOLU-
Dissolve 0.3569 gram of dried primary standard CaC03 in 5 ml. of conc. HC1 and dilute to 200 ml. (1 ml. = 1.0 mg. CaO). TION.
CALCIUM STANDARDSOLUTIOKS.
Pipet 5 , 6, 7, 8, 9, and 10 ml. of stock solution (1 ml. = 1.0 mg. CaO) into 1000-ml. volumetric flasks and make to marks with water. The flasks will contain the equivalent of 0.5% to 1.00% CaO present in the sample using the procedure given. VOL. 36, NO. 9, AUGUST 1964
1791
PREPARATION OF SAMFLAME ANALYSISAND MAG-
Procedure. PLE FOR NESIUM
DETERMINATION. Weigh 0.5000 gram of sample and place in a zirconium crucible. Add 8 grams of sodium peroxide and mix with a platinum rod. Cover and place in an electric muffle. Increase temperature tjo 800’ C. and hold for about 3 minutes. Remove crucible from muffle, take lid off, swirl contents up onto sides, and cool. Place crucible and lid in a covered 400-ml. beaker and cautiously add 7 5 ml. of water. Wash the crucible with hot wat)er and scrub out with a policeman using a few drops of 6 S HC1 to remove stains. I d d two stirring rods, 50 ml. of SaOH-Xa2C03 reagent, cover and boil for 10 minutes. Let stand hot for about 30 minutes. Filt,er hot on a 11 em. S o . 40 Whatman paper. Wash about 10 times with hot 2% SasCOI solut’ion. Then wash about 10 times with hot 0.27, IL”,OH solution to remove sodium salts and discard filtrate. Put a 100-ml. volumetric flask under the filter. Punch hole in filter and wash precipitate into flask with about 40 ml. of hot 1.V HC1. Wash with hot H20 almost to 100-ml. mark, and if solution is incomplete warm on hot plate to solution. Cool and make to volume. Pipet a 20-ml. aliquot into a tall 200-ml. beaker, precipitate R203 with NH40H, filter through a 9cm. Yo. 41 Whatman paper into a 100ml. flask, and wash with small increments of hot H20 to about 40-ml. volume. Return precipitate and paper to original beaker. -\dd 5 ml. of 2 S HC1 and
about 5 ml. of hot H20. Macerate paper, heat, reprecipitate Rz03, filter through 9-em. KO. 41 Whatman into same 100-ml. volumetric flask. Wash with hot HzO to almost 100-ml. volume. Cool, acidify with 3 ml. of 6 S HCl and make to mark. The sample is now ready for flame analysis. Instrument Technique. Fill 5-mL flame cups with distilled water, calcium flame standard (closest to unknown), and the unknown sample. Light burner and aspirate water into flame to clean burner. Turn recorder chart drive on. Rotat,e D U dark current control to place recorder pen a t an arbitrary zero point, ;Ispirate calcium flame standard. Open shutter of DC. Turn wavelengt’h drive clutch from manual to automatic. On completion of scan, turn wavelength drive clutch from automatic to manual. Close shutter of DU. Remove standard from flame and aspirate water to rinse. Set wavelength back to 430 mp manually. Repeat, using the unknown sample starting with “Rotate DLJ dark .” Measure the peak current. heights and jetermine the per cent CaO in the unknown by simple proportion. Correct for the CaO present in the sodium peroxide. Instrument Settings. Chart speed, 2 inches per minute; scan, 430 mp to 420 mp; scanning speed, 10; phototube, blue; selector switch, any position but “off”; resistor, 22 megohm (position Xo. 2) ; photomultiplier, full; slit, 0.03 mm.; filter, didymium; sensitivity (SERA 100% adjust), clock-
Analysis of N.B.S. Sample No. 103 Chrome Refractory (Results are single determinations on five separate samples) Si02 FeO crdh &Os CaO MgO 8.32 14.44 37,05 16,30 20.69 0.78 8.22 14.40 36,99 16.12 20.76 0.81 8.27 14,45 36.92 20.99 0 78 16.25 8.24 14.40 36,80 16.26 20.91 0.79 8.24 14.45 37,10 20.77 0 81 16.10 0 10 0.05 0.30 0.30 0.02 0.20 8.26 14.43 36.97 20.82 0.79 16.20
Table I.
Sample
Range Mean S.B.S. values 8 24 14.39 36,97 Mean error +O ,02 +0.04 0.00 Relative error, 70 +0.24 +0.28 0.00 Std. dev. 0.039 0,026 0.117 The various dilutions and aliquots used in analyzing Table 11.
20.83 -0.01
0.79 0.00
16,27 -0.07
-0.05 0.00 -0.43 0.123 0.016 0.090 the N.B.S. sample are given in
Table II. Dilutions and Aliquots Used for Analysis of N.B.S. Sample No. 103, Chrome Refractory Final aliquot Grams of into 100-ml. samples in Com-
pound
First dilution
Si02 Fe2Os .klsOs
( 0 2 g.-200 ml.) (0 2 g.-2OO rnl.) I n 2 e -200 ml,) (0.2 m1.j (0.5g.-100ml.) ( 0 5 g.-100 ml.)
i.-200
cr&
CaO
MgO
1792
e
Second dilution 25(0 025 g.-500 ml.) 25(0 025 g-500 ml.) 20(0 02 e-1000 ml,) ~ o ( 0 . 0g.-2000 2 ml:) 20(0.1 g.-100 rnl.) 20(0.1 g.-lOO ml.)
ANALYTICAL CHEMISTRY
color flask 50 ml. 25 ml. 20 ml. 15 ml. flame 50 ml. for
titration
color flask 0 0025 0 00125
0 0004
0 00015
wise limit; tank oxygen, 20 p.s.i.; panel oxygen, 15 p.s.i.; tank hydrogen, 10 p.s.i.; panel hydrogen, 5 p.s.i. MAGNESIUM DETERMINATION
Reagents. 0.02,V DCyTA. Disodium hydrogen - 1,2 - diaminocyclohexane A‘, Y ,S ’,N ’-t etraaceta t e. Dissolve 8.9 grams of DCyTA in about 200 ml. of water and stir with a magnetic stirrer. Decant to a 200-ml. volumetric flask and reserve any insolubles. Add 1.75 grams of S a O H and 25 ml. of water to the insolubles. Stir to solution and transfer to the 2000-ml. flask with water. Make t o volume. Standardize against 0.02N CaC12. 0.02N CaCL Keigh 1.0010 grams of dried primary standard CaC03 into a 1000-ml. volumetric flask. Add about 50 ml. of water and about 5 ml. of GL$) HC1. Boil off COZ, cool, and make to 1000 ml. wit,h water. CAL-RED INDICATOR. The trivial name for a 1:lOO salt mixture of the dye 2-hydroxg-l-(2-hydroxy-4-sulfo-1naphthylazo)-3-naI,lithoic acid. ERIOCHROVE BLACK T ISDICATOR: Grind 10 grams of SaC1, 0.8 gram of Na2B407.10H20, and 0.12 gram of Eriochrome Black T together xith a mortar and pestle. STASDARDIZATION OF 0.0LY DCpTX WITH 0.02.l‘ CaC12 SOLUTION. Pipet 25 ml. of 0.02S CaC12into a tall 200-ml. beaker containing a stirring bar. Make to approximately 50 ml. with water. Add a drop of methyl red indicator. Stir the solution with a magnet,ic stirrer and add 2.2’ KaOH dropnise until just alkaline. Add 2 nil. of lOY0 NaOH. Add 1 ml. of,3yc hydroxylamine hydrochloride solution and 1 ml. of 37, KCN solution. Add about 30 mg. of Cal-Red indicator and titrate with 0.02X DCyTA until t,he pink color begins t’o fade. Then add a few milligrams of indicator and titrate to the blue end point. Adjust the normality of the DCy‘l’A to e x a d y 0.0200N. Magnesium Titration. Pipet an aliquot from the flame anal flask not exceeding 50 ml. into a tall 200-ml. beaker containing a stirring bar. Make to 50 ml. with water. Add 1 drop of methyl red indicator. While stirring the solution with a magnetic stirrer, add 2 S K a O H dropwise until alkaline. Make just acid with GA’ HC1 and add 2 drops in excess. Add 2 ml. of NH40H-KHd.3 buffer. Add 1 ml. of 37, hydroxylamine hydrochloride solution and 1 ml. of 37, K C S solution. Add about 30 mg. of Eriochrome Black T indicator and titrate to the blue end 1)oint. This titration includes the calcium in the sample and the calcium in the sodium peroxide used for the fusion. The magnesium titration is corrected by subtracting the milliliters of DCyT*\ used t o titrate the calcium. The calcium correction value in milliliters is obtained by multiplying the total calcium found (by flame) by the weight of sample in the magnesium aliquot and dividing by the calciiini factor (0.05608).
The corrected magnesium titration multiplied by the magnesium titer (1 ml. = 0.0004032 gm. MgO) equals mg. of MgO present. RESULTS AND DISCUSSION
The Kational Bureau of Standards Sample Yo. 103, chrome refractory was analyzed to check the new system against classical procedures. The results of these analyses are shown in Table I. I n 1961, this laboratory participated in a round-robin analytical program requested by Eusner ( 7 ) . Six different laboratories were asked to analyze a number of basic refractory brick samples. In Table IC1 the averages of the results obtained on sample D-2 by the six laboratories using different methods are compared with the results obtained by this laboratory using the new rapid analysis scheme. Values obtained here were expressed to two decimal places; however, all roundrobin values of 1% or higher were reported to the nearest 0.1% by Eusner. Titania interferes with the alizarin red S procedure for alumina causing small plus errors. If appreciable titania is expected it may be determined on the ammonium hydroxide precipitate separated in the procedure for calcium and magnesium. An empirically derived table can be made to correct for the titania found as suggested by Shapiro and Brannock (16). For example, the alizarin red S value for alumina found on the N.B.S. chrome refractory would be reduced by 0.05%.
I n the determination of high percentages of chromium, alumina, and iron considerable care is necessary in all steps of procedure to obtain satisfactory precision and accuracy. The many precautions to be taken have been neatly summarized by Bennett, et al. (3). The rapid analysis methods presented have been applied successfully to samples of refractory grade chrome ore from the Philippine Islands, South Africa, Cuba, India, Turkey, Greece, Mexico, Montana, Oregon, and California. Moreover, the basic refractory products, consisting of chrome ore or combinations of chrome ore and magnesite, of many of the major domestic and foreign manufacturers have been analyzed using this new system of analysis. LITERATURE CITED
( 1 ) Am. Soc. Testing Materials, Phila-
delphia, Pa., “Manual of A.S.T.M. Standards on Refractory Materials,” p. 124, 1957. ( 2 ) Beckman Scientific and Process Instruments Division, Fullerton, Calif., Application Data Sheet UV-8070C. (1960). ( 3 ) Bennett, H., Eardley, R . P., Hawley, W. G., Thwaites, I., Trans. Brit. Ceram. Soc. 61,636 (1962). ( 4 ) Bunting, W. E., IND.ENG. CHEY., ANAL.ED. 16, 612 (1944). ( 5 ) Corey, R. B., Jackson, M. I,., ANAL. CHEM.25, 624 (1953). ( 6 ) Dinnin, J. I., U.S . Geol. Survey Bull. 1084-B (1959). ( 7 ) Eusner, G. R., Applied Research
Laboratory, I‘nited States Steel Corp., Monroeville, Pa., private communication, 1961. (8) Fortune, W. B., Mellon, M. G., IND. ENG.CHEM.,ANAL.ED. 10,60 (1938).
Table 111. Analysis of Chrome-Bearing Basic Refractory Brick Sample D-2 by Six Different Laboratories
Compound determined Si02 FeQO.(total &on ‘as) CrnOs AhOs CaO
Averages of round-robin values
MgO
3.20
-
6.00 12.60 11.50 1.00 65.50
Rapid method values 3.17 5.96 12.55 11.45 1.09 65.40
(One magnesium and one chromium result were outside the average deviation and were not included in the round-robin averages. )
(9) Goetz, C. A,, Debbrecht, F. J., ASAL. CHEM.27, 1972 (1955). (10) Hazel, W. M., Ibid., 24,196 (1952).
( 1 1 ) Hedin, R., “Colorimetric Methods for Rapid Analysis of Silicate Ma-
terials,” Swedish Cement and Concrete Research Institute, Royal Institute of Technology, Stockholm, 1947. (12) Parker, C. A,, Chddard, A. P., Anal.
Chim. Acta 4, 517 (1950). (13) Sandell, E. B., “Colorimetric Determination of Traces of lTetals,” Vol. 111, 3rd ed., p. 392, Interscience, New York, 1959. (14) Schwarzenbach!, G . , “Complexometric Titrations, p. 62, Interscience, New Yqrk, 1957. (15) Shapiro, L., Brannock, W. I%‘., c‘. S . Geol. Survey C‘irc. 165 (1952). (16) Ibid., U . S . Geol. Suroey Bull. 1144-A il962). \ - - - - ,
(17) Silverman,
I>., Hawley, D. W., ANAL.CHEM.28, 806 (1956). (18) Urone, P. F., Ibid., 27, 1354 (1955). RECEIVEDfor review XTarch 2, 1964. Accepted May 4, 1964.
Separation of Lead by Anion Exchanae JOHANN KORKISCH and FRANZ FElK Analytical Institute, University o f Vienna, Wahringerstrasse 38, Vienna, Austria
b A method for the anion exchange separation of lead from various elements employs the strongly basic onion exchange resin Dowex 1 , X8. As a medium for this separation, a mixture consisting of 90% tetrahydrofuran and 10% 5N nitric acid was selected. From this solution lead is adsorbed much more strongly on the resin than most other elements, so that an ion exchange separation by column chromatography b y using the mixture as the eluent is easily possible. Uranium, thorium, bismuth, thallium, the lanthanides from1 samarium to lutetium, iron, magnesium, calcium, and other elements pass quantitatively into the eluate, whereas the rare earth elements lanthanum to neodymium are
retained on the resin with lead. Lead is subsequently eluted with a mixture of 8OY0 tetrahydrofuran and 20% 2.5N nitric acid. The distribution coefficients were measured for numerous elements as a function of varying concentrations of nitric acid and tetrahydrofuran.
P
investigations have shown that lead cannot be adsorbed on strongly basic anion exchange resins from pure aqueous nitric acid media (1) because of the low tendency of the lead ions to form negatively charged nitrate complexes in such solutions. However, in partially nonaqueous media containing nitric acid the adsorption of lead is greatly enhanced by increasing REVIOUS
the nonaqueous component of the mixtures, so that high distribution values can be obtained. Fritz and coworkers ( 2 ) have shown that all that is required in the solution is a neutral complex, the anionic complex then being formed in the resin phase. For instance, Korkisch and hrrhenius (4) have measured a distribution coefficient of 261 for lead in an acetic acidnitric acid mixture. Fritz and Greene (S), on the other hand, found a value of 1100 in a 2-propanol-nitric acid mixture. I n methanol-nitric acid medium high adsorption of lead was earlier observed by Korkisch and Tera (6). A comparison of these lead values with those found for bismuth, thorium, and uranium under the same exlmiVOL. 36, NO. 9, AUGUST 1964
1793
