1、Designation: E 278 01 (Reapproved 2005)Standard Test Method for the Determination ofPhosphorus in Iron Ores by PhosphomolybdateCoprecipitation and Nitric Acid Titrimetry1This standard is issued under the fixed designation E 278; the number immediately following the designation indicates the year ofo
2、riginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of phospho-rus in
3、 iron ores, concentrates, and agglomerates.1.2 This test method covers the determination of phospho-rus in the concentration range from 0.01 to 1.00 %.1.3 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
4、 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Anal
5、ysis of Metals, Ores, andRelated MaterialsE 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 877 Practice for Sampling and Sample Preparation of IronOres and Relat
6、ed MaterialsE 882 Guide for Accountability and Quality Control in theChemical Analysis Laboratory3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 135.4. Summary of Test Method4.1 The sample is dissolved in hydrochloric and nitric acids.After the a
7、ddition of perchloric acid, the solution is evaporatedto strong fumes to dehydrate the silica. The insoluble residue isfiltered off, ignited, and treated for the recovery of anycontained phosphorus. Ammonium molybdate is added toprecipitate phosphomolybdate. The precipitate is filtered offand washed
8、 free from acid. It is then dissolved in an excess ofstandard sodium hydroxide solution. The excess sodium hy-droxide is titrated with a standard solution of nitric acid usingphenolphthalein as an indicator.5. Significance and Use5.1 This test method is intended to be used for compliancewith composi
9、tional specifications for phosphorus content. It isassumed that all who use these procedures will be trainedanalysts capable of performing common laboratory proceduresskillfully and safely. It is expected that work will be performedin a properly equipped laboratory and that proper wastedisposal proc
10、edures will be followed. Appropriate qualitycontrol practices shall be followed, such as those described inGuide E 882.6. Interferences6.1 Vanadium and arsenic, elements commonly found iniron ores, coprecipitate with the phosphorus. Provisions fortheir removal or elimination of their interference ar
11、e includedin this test method.6.2 Titanium tends to form an insoluble compound withphosphorus and thus may cause low values for phosphorus.Provision for its removal is included in this test method.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unles
12、s 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 first ascertained that the reagent is of sufficienthigh purity
13、to permit its use without lessening the accuracy ofthe determination.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 Related Metal-lurgic
14、al Materials.Current edition approved May 1, 2005. Published June 2005. Originallyapproved in 1965. Last previous edition approved in 2001 as E 278 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStan
15、dards volume information, refer to the standards Document Summary page onthe ASTM website.3“Reagent Chemicals, American Chemical Society Specifications,” Am. Chem.Soc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see “Reagent Chemicals and S
16、tandards,” by JosephRosin, D. Nostrand Co., Inc., NewYork, NY, and the “United States Pharmacopeia.”1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood
17、 to mean reagent water as definedby Type I of Specification D 1193.7.3 Ammonium Molybdate 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 c
18、omplete, filter through amedium paper, add 60 mL of HNO3, and cool.7.3.2 Solution No. 2Add 400 mL of HNO3to 960 mL ofwater in a 2L 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 bef
19、ore using. Useonly the clear supernatant liquid.7.4 Ammonium Nitrate (NH4NO3).7.5 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
20、 g of ferroussulfate (FeSO47H2O) in 1 L of sulfuric acid (H2SO4, 5 + 95).7.7 Hydrobromic Acid (1 + 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 hydrochloric acid (HCl, sp gr 1.19) and water.7.9 Hydro
21、fluoric Acid (sp gr 1.15)Concentrated hydrof-luoric acid (HF).7.10 Nitric Acid, Standard (0.15 N)Transfer 10 mL ofclear and water white concentrated nitric acid (HNO3,spgr1.42) to a 1-L flask, dilute to the mark, and mix. Standardizethis solution against the standard NaOH solution using phe-nolphtha
22、lein as indicator. If desired, this solution may be madeequivalent to the standard sodium hydroxide solution bydilution with water.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 Indicat
23、or SolutionDissolve 0.2 g ofphenolphthalein in 100 mL of ethanol.7.14 Potassium Nitrate, Wash Solution (10 g/L)Dissolve10 g of potassium nitrate (KNO3) in water, dilute to 1 L, andmix.7.15 Potassium Permanganate Solution (25 g/L)Dissolve25 g of potassium permanganate (KMnO4) in water and diluteto1L.
24、7.16 Sodium Carbonate (Na2CO3).7.17 Sodium Hydroxide, Stock SolutionDissolve 300 g ofsodium hydroxide (NaOH) in 1 L of water. Add a slight excessof barium hydroxide (Ba(OH)2) to precipitate any carbondioxide (CO2). Allow any precipitate to settle out. Store thesolution in a polyethylene container.7.
25、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 boiled and cooled waterand mix thoroughly. Standardize this solution against potas-sium acid phthalate. It is convenient to adjust the normality ofthi
26、s 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 iron 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
27、.1 For precautions to be observed in this test method, referto Practices E50.9. Sampling and Sample Preparation9.1 SamplingThe gross sample shall be collected andprepared in accordance with Practice E 877.9.2 Sample PreparationThe laboratory sample shall bepulverized to pass a No. 100 (150-m) sieve.
28、NOTE 1Some ores, such as specular hematites, may require finergrinding to pass a No. 200 (75-m) sieve.9.3 Sample WeightWeigh approximately (within 625mg) 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. Procedure
29、10.1 Transfer the test sample to a small dry weighing bottleand place in a drying oven. After drying at 105 to 110C for 1h, cap the bottle, and cool to room temperature in a desiccator.Momentarily release the cap to equalize pressure and weigh thecapped bottle to the nearest 0.1 mg. Repeat the dryin
30、g andweighing until there is no further weight loss. Transfer the testsample to a 400-mL beaker and reweigh the capped bottle tothe nearest 0.1 mg. The difference between the two weights isthe weight of the test sample.10.2 Moisten the test sample with a few milliliters of waterand add 25 mL of HCl
31、for each gram of test sample. Cover anddigest below the boiling point until all soluble minerals are insolution. Add 5 mL of HNO3and 20 mL of HClO4andevaporate to strong fumes to dehydrate the silica. Cool, add 50mL of water, and warm until soluble salts are in solution. Filterand collect the filtra
32、te in a 300-mL Erlenmeyer flask. Wash theresidue with HNO3(1 + 99), and finally with hot water untilfree from perchlorates. Evaporate the filtrate using a 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, a
33、nd evaporate to complete dryness.Fuse the residue with3gofNa2CO3. Place the 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
34、 the filtrate in the 400-mLbeaker. Wash the residue with hot water and discard. Acidifythe filtrate with HCl, add 5 mL of the FeCl3solution, andrender the solution alkaline to litmus with NH4OH. Boil for 1min to coagulate the precipitate. Filter and wash the residuewith hot water. Discard the filtra
35、te. Place the flask containingthe evaporated filtrate from 10.2 underneath the funnel. Dis-solve the residue through the paper with 10 mL of warm HClE 278 01 (2005)2(1 + 1) and wash with hot water. Discard the paper andevaporate the solution to fumes of HClO4.NOTE 2If the test sample is high in mang
36、anese, manganese dioxide(MnO2) may precipitate when the solution is evaporated to perchloric acidfumes. If this occurs, the MnO2can be redissolved by the addition of acrystal of sodium nitrite (NaNO2) when the perchlorates are dissolved inwater.NOTE 3If arsenic is known to be present, concentrate th
37、e solution inthe Erlenmeyer flask to approximately 75 mL, add 20 mL of HBr (1 + 4),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 KMn
38、O4solution andboil the solution for several minutes.Add, dropwise, enough ofa solution 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 justd
39、issolves on shaking, then 3 to 5 mL in excess. Add 10 g ofNH4NO3and shake to dissolve the salts.10.5 Absence of VanadiumAdjust the volume to 150 mLand the temperature to 20C and add 50 mL of the ammoniummolybdate solution. Shake vigorously for 5 min and let stand20 min or until the yellow precipitat
40、e has settled.NOTE 4If the precipitate is small it is advisable to allow it to stand 4h or overnight.10.6 Presence of VanadiumAdjust the volume of thesolution to 100 mL, cool to 15C, add 5 mL of the FeSO4solution and swirl the flask to reduce the vanadium.Add 50 mLof the ammonium molybdate solution,
41、 shake vigorously for 10min, and let stand for1horuntil the yellow precipitate 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 wi
42、th the KNO3wash solution until free fromacid, as indicated by a litmus paper 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
43、pad may be used if desired.10.8 Return the paper and precipitate to the Erlenmeyerflask, add 25 mL of water (CO2-free), and an excess of 5 mLof 0.15 N NaOH solution. Shake or stir to break up the paperand to dissolve the precipitate. Wash down the sides of theflask, add 3 drops of the phenolphthalei
44、n indicator solution,and titrate the excess NaOH with the 0.15 N HNO3.10.9 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
45、 D 2 EC!#FG(1)where:A = standard NaOH solution used, mL,B = standard HNO3required 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 blank determina-tion, mL,E = standard HNO3required
46、 for titration of the excessNaOH in blank determination, mL,F = phosphorus 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 E 691. To interpolate forreprod
47、ucibility factors, R, between 0.009 and 0.60 % phospho-rus (P), the following relationship may be used:R 5 0.013 1 0.0781% P! 2 0.0504% P!2(2)12.2 BiasThere was no significant bias in the determina-tions made for an NIST certified reference material, NBS 27d,certified at 0.028 % phosphorus. An addit
48、ional CRM, NBS27c, certified as having 0.042 % phosphorus, was analyzed bytwo laboratories as having 0.038 or 0.041 % phosphorus.13. Keywords13.1 agglomerates; concentrates; iron ore; phosphorus; re-lated materials; titrimetric phosphorus4Supporting data giving the results of cooperative testing hav
49、e been filed atASTM International Headquarters. Request RR:E16-174.TABLE 1 Statistical SummaryAAverageConcentration,B%Standard DeviationReproducibility,RCNumber ofParticipatingLaboratoriesWithin-LaboratoryBetween-Laboratories0.009 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 E 691.BEach concentration represents a different kind of iron ore.CReproducibility factor, R, obtained by multiplying th
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