1、Designation: E278 01 (Reapproved 2015)1Standard Test Method forDetermination of Phosphorus in Iron Ores byPhosphomolybdate Coprecipitation and Nitric AcidTitrimetry1This standard is issued under the fixed designation E278; the number immediately following the designation indicates the year oforigina
2、l adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections were made in 1.2 and Table 1.1. Scope1.1 This test
3、method covers the determination of phospho-rus in iron ores, concentrates, and agglomerates.1.2 This test method covers the determination of phospho-rus in the range from 0.01 % to 1.00 %.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in t
4、hisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.
5、Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE691 Pract
6、ice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE877 Practice for Sampling and Sample Preparation of IronOres and Related Materials for Determination of Chemi-cal Composition and Physical PropertiesE882 Guide for Accountability and Quality Control in theChemical
7、 Analysis Laboratory3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E135.4. Summary of Test Method4.1 The sample is dissolved in HCl and HNO3. After theaddition of HClO4, the solution is evaporated to strong fumesto dehydrate the silica. The insolu
8、ble residue is filtered off,ignited, and treated for the recovery of any contained phos-phorus. Ammonium molybdate is added to precipitate phos-phomolybdate. The precipitate is filtered off and washed freefrom acid. It is then dissolved in an excess of standard sodiumhydroxide solution. The excess s
9、odium hydroxide is titratedwith a standard solution of HNO3using phenolphthalein as anindicator.5. Significance and Use5.1 This test method is intended to be used for compliancewith compositional specifications for phosphorus content. It isassumed that all who use these procedures will be trainedana
10、lysts capable of performing common laboratory proceduresskillfully and safely. It is expected that work will be performedin a properly equipped laboratory and that proper wastedisposal procedures will be followed. Appropriate qualitycontrol practices shall be followed, such as those described inGuid
11、e E882.6. Interferences6.1 Vanadium and arsenic, elements commonly found iniron ores, coprecipitate with the phosphorus. Provisions fortheir removal or elimination of their interference are includedin this test method.6.2 Titanium tends to form an insoluble compound withphosphorus and thus may cause
12、 low values for phosphorus.Provision for its removal is included in this test method.1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Rela
13、ted Metal-lurgical Materials.Current edition approved Nov. 15, 2015. Published December 2015. Originallyapproved in 1965. Last previous edition approved in 2010 as E278 01 (2010)1.DOI: 10.1520/E0278-01R15E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custome
14、r Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Reagents and Materials7.1 Purity of
15、ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.3Other grades may be used,provided it is
16、 first ascertained that the reagent is of sufficienthigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type II of Specification D1193.7.3 Ammonium Mo
17、lybdate Solution (Acidic).7.3.1 Solution No. 1Transfer 100 g of molybdic acid(85 % MoO3) to a 600mL beaker containing 240 mL of waterand mix thoroughly. Add 140 mL of NH4OH while stirringvigorously. When dissolution is complete, filter through amedium paper, add 60 mL of HNO3, and cool.7.3.2 Solutio
18、n No. 2Add 400 mL of HNO3to 960 mL ofwater in a 2-L beaker and cool.7.3.3 Add Solution No. 1 to Solution No. 2 while stirringconstantly. Add 0.1 g of ammonium phosphate, dibasic(NH4)2HPO4), and let stand at least 24 h before using. Useonly the clear supernatant liquid.7.4 Ammonium Nitrate (NH4NO3)7.
19、5 Ferric Chloride SolutionDissolve 0.3 g of pure ironwire in 25 mL of HCl (1 + 1). Oxidize by adding HNO3dropwise to the hot solution. Cool, add 25 mL of HCl, dilute to1 L and mix.7.6 Ferrous Sulfate SolutionDissolve 100 g of ferroussulfate (FeSO47H2O) in 1 L of H2SO4(5 + 95).7.7 Hydrobromic Acid (1
20、 + 4)Mix 20 mL of concentratedhydrobromic acid (HBr, sp gr 1.49) with 80 mL of water.7.8 Hydrochloric Acid (1 + 1)Mix equal volumes of con-centrated HCl (sp gr 1.19) and water.7.9 Hydrofluoric Acid (sp gr 1.15)Concentrated HF.7.10 Nitric Acid, Standard (0.15 N)Transfer 10 mL ofclear and water white
21、concentrated HNO3(sp gr 1.42) to a 1-Lflask, dilute to the mark, and mix. Standardize this solutionagainst the standard sodium hydroxide (NaOH) solution usingphenolphthalein as indicator. If desired, this solution may bemade equivalent to the standard sodium hydroxide solution bydilution with water.
22、7.11 Nitric Acid, Wash Solution (1 + 99)Mix 10 mL ofconcentrated HNO3(sp gr 1.42) with 990 mL of water.7.12 Perchloric Acid (70 %) (HClO4).7.13 Phenolphthalein Indicator SolutionDissolve 0.2 g ofphenolphthalein in 100 mL of ethanol.7.14 Potassium Nitrate, Wash Solution (10 g L)Dissolve10 g of potass
23、ium nitrate (KNO3) in water, dilute to 1 L, andmix.7.15 Potassium Permanganate Solution (25 g L)Dis-solve 25 g of potassium permanganate (KMnO4) in water anddilute to 1 L.7.16 Sodium Carbonate (Na2CO3).7.17 Sodium Hydroxide, Stock SolutionDissolve 300 g ofNaOH in 1 L of water.Add a slight excess of
24、barium hydroxide(Ba(OH)2) to precipitate any carbon dioxide (CO2). Allow anyprecipitate to settle out. Store the solution in a polyethylenecontainer.7.18 Sodium Hydroxide, Standard Solution (0.15 N)Transfer 20 mL of the clear, supernatant stock solution to a 1-Lflask. Dilute to the mark with freshly
25、 boiled and cooled waterand mix thoroughly. Standardize this solution against potas-sium acid phthalate. It is convenient to adjust the normality ofthis standard solution to 0.148 N (1 mL = 0.0002 g P). Confirmthe phosphorus value by analyzing a standard of a knownphosphorus content, preferably an i
26、ron ore of similar compo-sition. Protect the NaOH solution from CO2by means of asoda-lime or soda-asbestos tube.7.19 Sulfurous Acid (H2SO3).8. Hazards8.1 For precautions to be observed in this test method, referto Practices E50.9. Sampling and Sample Preparation9.1 SamplingThe gross sample shall be
27、collected andprepared in accordance with Practice E877.9.2 Sample PreparationThe laboratory sample shall bepulverized to pass a No. 100 (150-m) sieve.NOTE 1Some ores, such as specular hematites, may require finergrinding to pass a No. 200 (75-m) sieve.9.3 Sample WeightWeigh approximately (within6 25
28、 mg) an amount of sample specified as follows:Content of Phosphorus, % Weight of Sample, g0.01 to 0.10 2.00.11 to 0.50 1.00.51 to 1.00 0.510. Procedure10.1 Transfer the test sample to a small dry weighing bottleand place in a drying oven.After drying at 105 C to 110 C for1 h, cap the bottle, and coo
29、l to room temperature in adesiccator. Momentarily release the cap to equalize pressureand weigh the capped bottle to the nearest 0.1 mg. Repeat thedrying and weighing until there is no further weight loss.Transfer the test sample to a 400-mL beaker and reweigh thecapped bottle to the nearest 0.1 mg.
30、 The difference between thetwo weights is the weight of the test sample.10.2 Moisten the test sample with a few milliliters of waterand add 25 mL of HCl for each gram of test sample. Cover anddigest below the boiling point until all soluble minerals are in3Reagent Chemicals, American Chemical Societ
31、y Specifications, AmericanChemical Society, Washington, DC, www.chemistry.org. For suggestions on thetesting of reagents not listed by the American Chemical Society, see the UnitedStates Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention,Inc. (USPC), Rockville, MD, http:/www.usp.org.
32、E278 01 (Reapproved 2015)12solution. Add 5 mL of HNO3and 20 mL of HClO4andevaporate to strong fumes to dehydrate the silica. Cool, add50 mL of water, and warm until soluble salts are in solution.Filter and collect the filtrate in a 300-mL Erlenmeyer flask.Wash the residue with HNO3(1 + 99), and fina
33、lly with hotwater until free from perchlorates. Evaporate the filtrate usinga low heat.10.3 Ignite the paper and residue in a platinum crucible.Cool, moisten with several drops of water and add 2 mL ofHClO4and 5 mL of HF, and evaporate to complete dryness.Fuse the residue with 3 g of Na2CO3. Place t
34、he crucible in a250-mL beaker and add 100 mL of water. Heat to disintegratethe melt and to dissolve all soluble salts. Remove, wash, andpolice the crucible. Filter the alkaline solution through amedium-texture paper and collect the filtrate in the 400-mLbeaker. Wash the residue with hot water and di
35、scard. Acidifythe filtrate with HCl, add 5 mL of the ferric chloride (FeCl3)solution, and render the solution alkaline to litmus withNH4OH. Boil for 1 min to coagulate the precipitate. Filter andwash the residue with hot water. Discard the filtrate. Place theflask containing the evaporated filtrate
36、from 10.2 underneaththe funnel. Dissolve the residue through the paper with 10 mLof warm HCl (1 + 1) and wash with hot water. Discard thepaper and evaporate the solution to fumes of HClO4.NOTE 2If the test sample is high in manganese, manganese dioxide(MnO2) may precipitate when the solution is evap
37、orated to HClO4fumes.If this occurs, the MnO2can be redissolved by the addition of a crystal ofsodium nitrite (NaNO2) when the perchlorates are dissolved in water.NOTE 3If arsenic is known to be present, concentrate the solution inthe Erlenmeyer flask to approximately 75 mL, add 20 mL of HBr (1 + 4)
38、,and evaporate to strong fumes. Cool, wash down the sides of the flask with20 mL of water and again evaporate to fumes.10.4 Cool, add 50 mL of water, and warm to dissolve thesalts. Add an excess of several drops of KMnO4solution andboil the solution for several minutes.Add, dropwise, enough ofa solu
39、tion of H2SO3to reduce any KMnO4or precipitatedMnO2. Boil to expel the SO2, cool, and add NH4OH until asmall precipitate of ferric hydroxide (Fe(OH)3) persists onshaking or stirring. Add HNO3until the precipitate justdissolves on shaking, then 3 mL to 5 mL in excess.Add 10 g ofNH4NO3and shake to dis
40、solve the salts.10.5 Absence of VanadiumAdjust the volume to 150 mLand the temperature to 20 C and add 50 mL of the ammoniummolybdate solution. Shake vigorously for 5 min and let stand20 min or until the yellow precipitate has settled.NOTE 4If the precipitate is small it is advisable to allow it to
41、stand 4 hor overnight.10.6 Presence of VanadiumAdjust the volume of thesolution to 100 mL, cool to 15 C, add 5 mL of the FeSO4solution and swirl the flask to reduce the vanadium.Add 50 mLof the ammonium molybdate solution, shake vigorously for10 min, and let stand for 1 h or until the yellow precipi
42、tate hassettled (Note 4).10.7 Filter the precipitate obtained in accordance with 10.5or 10.6 on a close textured paper (Note 5). Wash the flask andprecipitate three times with 5-mL portions of the HNO3washsolution, and then with the KNO3wash solution until free fromacid, as indicated by a litmus pap
43、er test. Since the yellowprecipitate tends to climb, direct the jet of the wash solutionaround the edge of the paper and spirally down.NOTE 5Afiltering crucible or smooth funnel plus perforated disk witha macerated paper pulp pad may be used if desired.10.8 Return the paper and precipitate to the Er
44、lenmeyerflask, add 25 mL of water (CO2-free), and an excess of 5 mL of0.15 N NaOH solution. Shake or stir to break up the paper andto dissolve the precipitate. Wash down the sides of the flask,add three drops of the phenolphthalein indicator solution, andtitrate the excess NaOH with the 0.15 N HNO3.
45、10.9 BlankCarry along with the test sample a reagentblank through all the steps of the procedure using the sameamounts of all reagents.11. Calculation11.1 Calculate the percent of phosphorus as follows:Phosphorus, % 5 100A 2 BC! 2 D 2 EC!#FG(1)where:A = standard NaOH solution used, mL,B = standard H
46、NO3required for titration of the excess ofNaOH in the test sample, mL,C = standard NaOH solution equivalent to 1 mL of thestandard HNO3, mL,D = standard NaOH solution required for blankdetermination, mL,E = standard HNO3required for titration of the excessNaOH in blank determination, mL,F = phosphor
47、us equivalent of the standard NaOH solution,g/mL, andG = weight of test sample used.12. Precision and Bias412.1 PrecisionTable 1 indicates the precision of the testmethod as determined by Practice E691. To interpolate forreproducibility factors, R, between 0.009 % and 0.60 % phos-phorus (P), the fol
48、lowing relationship may be used:4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E16-174.TABLE 1 Statistical SummaryAAverage,B%Standard DeviationReproducibility,RCNumber ofParticipatingLaboratoriesWithin-LaboratoryBetween-Laborat
49、ories0.009 0.0007 0.0008 0.0021 50.028 0.0008 0.0008 0.0024 70.031 0.0012 0.0016 0.0045 70.044 0.0017 0.0018 0.0051 70.086 0.0014 0.0027 0.0075 70.596 0.0106 0.0106D0.0300 7ACalculations based on Practice E691.BEach percentage represents a different kind of iron ore.CReproducibility factor, R, obtained by multiplying the between-laboratory stan-dard deviation by 22.DProvisional calculation of between-laboratories standard deviation was 0.0089.E278 01 (Reapproved 2015)13R 5 0.01310.0781% P! 2 0.0504% P!2(2)12.2 BiasThere was no
