ISO 5416-2006 Direct reduced iron - Determination of metallic iron - Bromine-methanol titrimetric method《直接还原铁 金属铁含量的测定 溴-甲醇滴定法》.pdf

1、 Reference number ISO 5416:2006(E) ISO 2006INTERNATIONAL STANDARD ISO 5416 Third edition 2006-04-01 Direct reduced iron Determination of metallic iron Bromine-methanol titrimetric method Minerais de fer prrduits Dosage du fer mtallique Mthode titrimtrique au brome-mthanol ISO 5416:2006(E) PDF discla

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4、 file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2006 All rig

5、hts reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of th

6、e requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2006 All rights reservedISO 5416:2006(E) ISO 2006 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 N

7、ormative references . 1 3 Principle. 1 4 Reagents 2 5 Apparatus 3 6 Sampling and samples. 3 6.1 Laboratory sample 3 6.2 Preparation of test samples. 3 7 Procedure 3 7.1 Number of determinations . 3 7.2 Test portion . 3 7.3 Blank test and check test. 3 7.4 Determination of hygroscopic moisture conten

8、t 4 7.5 Determination 4 8 Expression of results . 5 8.1 Calculation of mass fraction of metallic iron. 5 8.2 General treatment of results 5 9 Test report . 7 Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for test samples 8 Annex B (informative) Derivation of

9、repeatability and permissible tolerance equations . 9 Annex C (informative) Precision data obtained by international analytical trials . 10 Annex D (informative) Determination of degree of metallization 11 Annex E (informative) Decontamination of the waste solutions from the analysis 12 ISO 5416:200

10、6(E) iv ISO 2006 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body i

11、nterested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechn

12、ical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by th

13、e technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights

14、. ISO shall not be held responsible for identifying any or all such patent rights. ISO 5416 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron, Subcommittee SC 2, Chemical analysis. This third edition cancels and replaces the second edition (ISO 5416:1997), which has be

15、en technically revised. It has been updated to alter the manner in which precision data are presented. INTERNATIONAL STANDARD ISO 5416:2006(E) ISO 2006 All rights reserved 1 Direct reduced iron Determination of metallic iron Bromine-methanol titrimetric method WARNING This International Standard may

16、 involve hazardous materials, operations and equipment. This International Standard does not purport to address all of the safety issues associated with its use. It is the responsibility of the user to establish appropriate health and safety practices and determine the applicability of regulatory li

17、mitations prior to use. 1 Scope This International Standard specifies a titrimetric method for the determination of the mass fraction of metallic iron in reduced iron ores (direct reduced iron: DRI). This method is applicable to mass fractions of metallic iron between 15 % and 95 % in DRI. NOTE The

18、term “metallic iron” means those forms of iron not bonded to oxygen or not present as pyrite. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edi

19、tion of the referenced document (including any amendments) applies. ISO 385, Laboratory glassware Burettes ISO 648, Laboratory glassware One-mark pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 2596, Iron ores Determination of hygroscopic moisture in analytical samples Gravime

20、tric, Karl Fischer and mass-loss methods ISO 2597-1, Iron ores Determination of total iron content Part 1: Titrimetric method after tin(II) chloride reduction ISO 3696, Water for analytical laboratory use Specification and test methods ISO 10835, Direct reduced iron and hot briquetted iron Sampling

21、and sample preparation 3 Principle Metallic iron is dissolved by treatment with bromine-methanol solution. The insoluble residue is separated by filtration. The iron in the filtrate is reduced to iron(II), which is titrated with potassium dichromate solution. NOTE Other metallic elements, such as ch

22、romium, cobalt, manganese, nickel and vanadium, are also dissolved by the bromine-methanol solution but, except for vanadium, they do not interfere with the titration procedure. ISO 5416:2006(E) 2 ISO 2006 All rights reserved4 Reagents During the analysis, use only reagents of recognized analytical

23、grade and only water that complies with grade 2 of ISO 3696. 4.1 Hydrochloric acid, 1,16 g/ml to 1,19 g/ml. 4.2 Sulfuric acid, 1,84 g/ml, diluted 1 + 1. 4.3 Methanol, Karl Fischer reagent grade, max. 0,1 % H 2 O. 4.4 Bromine-methanol solution, 50 ml/l. Dissolve 5 ml of bromine in 95 ml of methanol (

24、4.3). This solution shall be freshly prepared and used immediately. WARNING The preparation of the bromine-methanol solution, and all stages of the procedure where bromine is present, shall be carried out in an efficient fume cupboard. 4.5 Hydrogen peroxide solution, 30 % (V/V). 4.6 Tin(II) chloride

25、 solution, 100 g/l. Dissolve 119 g of tin(II) chloride dihydrate (SnC1 2 2H 2 O), successively in small amounts, with 200 ml of hydrochloric acid (4.1) by warming. Cool, dilute to 1 litre and mix. Add 2 g of coarsely granulated tin and store the solution in a brown bottle. 4.7 Mercury(II) chloride s

26、olution, 50 g/l. Dissolve 50 g of mercury(II) chloride (HgCl 2 ) in 800 ml of hot water. Cool, dilute to 1 litre and mix. 4.8 Sulfuric acid/phosphoric acid mixture. Add cautiously, while stirring, 150 ml of sulfuric acid ( 1,84 g/ml) and 150 ml of phosphoric acid ( 1,7 g/ml) to 600 ml of water. Cool

27、, dilute to 1 litre and mix. 4.9 Iron standard solution. Dissolve 0,800 g of high purity iron(III) oxide (Fe 2 O 3 99 %) in 40 ml of hydrochloric acid (4.1). Dilute to 1 000 ml and mix. 1 ml of this solution contains 0,558 mg of iron. If the purity of the iron(III) oxide is unknown, the solution sho

28、uld be standardized using a 100 ml aliquot evaporated to a low volume. 4.10 Potassium dichromate, standard volumetric solution, c(K 2 Cr 2 O 7 ) = 0,016 67 mol/l. Pulverize about 6 g of potassium dichromate in an agate mortar, dry at 140 C to 150 C for 2 h, then cool to room temperature in a desicca

29、tor. Weigh 4,903 g of the dried material, dissolve in water and transfer to a 1 000 ml volumetric flask. Dilute to volume with water and mix. 4.11 Sodium diphenylamine sulfonate, 2 g/l solution. Dissolve 0,2 g of sodium diphenylamine sulfonate (C 6 H 5 NHC 6 H 4 SO 3 Na) in 100 ml of water. Store th

30、e solution in a brown glass bottle. ISO 5416:2006(E) ISO 2006 All rights reserved 3 5 Apparatus Ordinary laboratory apparatus, including one-mark pipettes and one-mark volumetric flasks complying with the specifications of ISO 648 and ISO 1042 respectively, and the following 5.1 Burette, complying w

31、ith the specifications of ISO 385. 5.2 Conical flask, of capacity 100 ml, diameter 50 mm to 60 mm, without concave base, for dissolving the sample. A watch-glass or reflux condenser is required if working outside a fume cupboard. 5.3 Magnetic stirrer (rotational frequency 200 min 1to 400 min 1 ), ma

32、gnetic stirring bar without pivot ring, polytetrafluoroethylene (PTFE) coated; diameter 5 mm, length 40 mm. 5.4 Filtering apparatus, with glass-fibre filters or plastics micro-filters 1) , in either case with a pore size of less than 1 m. 6 Sampling and samples 6.1 Laboratory sample For analysis, us

33、e a laboratory sample of minus 160 m particle size which has been taken and prepared in accordance with ISO 10835. 6.2 Preparation of test samples Thoroughly mix the laboratory sample using non-magnetic materials. Taking multiple increments with a non-magnetic spatula, extract a test sample of not l

34、ess than 25 g in such a manner that it is representative of the whole contents of the container. Prepare an air-equilibrated test sample in accordance with ISO 2596. 7 Procedure 7.1 Number of determinations Carry out the analysis at least in duplicate in accordance with Annex A, independently, on on

35、e air-equilibrated test sample. NOTE The expression “independently” means that the second and any subsequent result is not affected by the previous result(s). For this particular analytical method, this condition implies that the repetition of the procedure is carried out either by the same operator

36、 at a different time, or by a different operator including, in either case, appropriate recalibration. 7.2 Test portion Taking several increments using a non-magnetic spatula, weigh, to the nearest 0,000 2 g, approximately 0,50 g of the air-equilibrated test sample (6.2). 7.3 Blank test and check te

37、st In each run, one blank test and one analysis of a certified reference material of the same type of DRI shall be carried out in parallel with the analysis of the sample(s) under the same conditions. A test sample of the certified reference material shall be prepared as specified in 6.2. 1) PVC fil

38、ters or PVF filters. ISO 5416:2006(E) 4 ISO 2006 All rights reservedThe certified reference material should be of the same type as the sample to be analysed, and the properties of the two materials should be sufficiently similar to ensure that, in either case, no significant changes in the analytica

39、l procedure become necessary. When the analysis is carried out on several samples at the same time, the blank value may be represented by one test, provided that the procedure is the same and the reagents used are from the same reagent bottles. When the analysis is carried out on several samples of

40、the same type of DRI at the same time, the analytical value of one certified reference material may be used. 7.4 Determination of hygroscopic moisture content Determine the hygroscopic moisture content in accordance with ISO 2596, simultaneously with the taking of the test portion (7.2) for the dete

41、rmination of the mass fraction of metallic iron. 7.5 Determination 7.5.1 Dissolution of metallic iron Place the test portion (7.2) in a thoroughly dry 100 ml conical flask (5.2), add 50 ml of bromine-methanol solution (4.4), cover with a watch-glass, or fit a reflux condenser, and stir continuously

42、with the magnetic stirrer for 30 min (see the next paragraph) at a temperature of 20 C. Filter immediately through a glass-fibre filter or plastics microfilter (5.4) under suction and collect the filtrate in a suction filter flask. Wash the filter with methanol (4.3) (e.g. six times with 5 ml portio

43、ns) until the washings are colourless (free from bromine), then wash a further three times with water to remove the methanol. Transfer the solution to a 600 ml beaker, washing with water. A dissolution time of 30 min is usually adequate. To ensure complete dissolution, two different dissolution time

44、s should be used. If 30 min has been taken for the first test portion, the replicate test portion should be digested for twice this time, i.e. 60 min. This procedure should be repeated, increasing the digestion time until agreement is reached between replicate determinations. 7.5.2 Determination of

45、metallic iron Add 20 ml of sulfuric acid (4.2) to the total filtrate, heat the solution cautiously until fumes of sulfuric acid appear, then continue the heating until strong fuming takes place. Remove from the hotplate, cool and add 10 ml of hydrogen peroxide solution (4.5). Evaporate until sulfuri

46、c acid fumes again evolve. Cool and repeat the oxidation with hydrogen peroxide (bromides and methanol are to be completely removed). Add some water, rinsing the walls of the beaker, and heat again until fuming takes place. Cool, carefully add about 140 ml of water and 25 ml of hydrochloric acid (4.

47、1) and boil until all salts are redissolved. For mass fractions of metallic irons greater than 50 %, cool the solution, transfer quantitatively to a 200 ml volumetric flask, dilute to volume and mix. Measure a 100,0 ml aliquot into a 600 ml beaker, add 10 ml of hydrochloric acid (4.1) and proceed fr

48、om the addition of tin(II) chloride. Add tin(II) chloride solution (4.6) to the boiling solution, drop by drop while stirring, until the solution is just colourless, then add 2 drops in excess. Rinse the walls of the beaker and cool quickly, dilute with water to 300 ml and add 15 ml of mercury(II) c

49、hloride solution (4.7). Wait for about 5 min until slight turbidity appears, add 25 ml of sulfuric acid/phosphoric acid mixture (4.8) and 1,0 ml of sodium diphenylamine sulfonate solution (4.11), and titrate with potassium dichromate solution (4.10) until one drop produces a change in colour from green to purple. 7.5.3 Blank test Determine the blank test value in the same manner, using all reagents but adding 10 ml of standard iron solution (4.9) in place of the test portion. Add the standard iron solu