1、BRITISH STANDARD BS7020-4.2: 1990 ISO9507:1990 Analysis of iron ores Part 4: Method for the determination of total iron content Section 4.2 Titanium(III) chloride reduction methodsBS7020-4.2:1990 This British Standard, having been prepared under the directionof the Iron and Steel Standards Policy Co
2、mmittee, waspublished under the authorityof the Board of BSIandcomes into effect on 31 October1990 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference ISM/58 Draft for comment87/44676DC ISBN 0 580 19020 X Committees responsible for this British Standard
3、The preparation of this British Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-) to Technical Committee ISM/58, upon which the following bodies were represented: British Steel Industry Institution of Mining and Metallurgy Coopted members The following body was also rep
4、resented in the drafting of the standard, through subcommittees and panels: British Ceramic Research Ltd. Amendments issued since publication Amd. No. Date CommentsBS7020-4.2:1990 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative referen
5、ces 1 3 Principle 1 4 Reagents 1 5 Apparatus 2 6 Sampling and samples 3 7 Procedure 3 8 Expression 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 precision statements 9 Table 1
6、 Precision 6 Table B.1 Total iron contents of test samples 9 Publication(s) referred to Inside back coverBS7020-4.2:1990 ii BSI 10-1999 National foreword This Section of BS7020 has been prepared under the direction of the Iron and Steel Standards Policy Committee. It is identical with ISO9507:1990 “
7、Iron ores determination of total iron content Titanium(III) chloride reduction methods” published by the International Organization for Standardization (ISO). The Technical Committee has reviewed the provisions of ISO385-1 and ISO648 to which reference is made in the text and has decided that they a
8、re acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from leg
9、al obligations. Cross-references International Standard Corresponding British Standard ISO1042:1981 BS1792:1982 Specification for one-mark volumetric flasks (Identical) BS7020 Analysis of iron ores ISO2596:1984 Part2:1988 Method for the determination of hygroscopic moisture in analytical samples (Id
10、entical) BS5660 Methods of sampling iron ores ISO3081:1986 Part1:1987 Manual method of increment sampling (Identical) ISO3082:1987 Part2:1987 Mechanical method of increment sampling and sample preparation (Identical) ISO3083:1986 BS5661:1987 Method for preparation of samples of iron ores by manual m
11、eans (Identical) BS7020 Analysis of iron ores ISO7764:1985 Part1:1988 Method for the preparation of pre-dried test samples for chemical analysis Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to10, an inside back cover and a back cover. This stand
12、ard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7020-4.2:1990 BSI 10-1999 1 1 Scope This International Standard specifies two titrimetric methods, free from mercury pollution, for the determ
13、ination of total iron content in iron ores, using potassium dichromate as titrant after reduction of the iron(III) by tin(II) chloride and titanium(III) chloride. The excess reductant is then oxidized by either dilute potassium dichromate (method1) or perchloric acid (method2). Both methods are appl
14、icable to a concentration range of30%(m/m) to72%(m/m) of iron in natural iron ores, iron ore concentrates and agglomerates, including sinter products. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International
15、Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members
16、of IEC and ISO maintain registers of currently valid International Standards. ISO385-1:1984, Laboratory glassware Burettes Part1: General requirements. ISO648:1977, Laboratory glassware One-mark pipettes. ISO1042:1983, Laboratory glassware One-mark volumetric flasks. ISO2596:1984, Iron ores Determin
17、ation of hygroscopic moisture in analytical samples Gravimetric and Karl Fischer methods. ISO3081:1986, Iron ores Increment sampling Manual method. ISO3082:1987, Iron ores Increment sampling and sample preparation Mechanical method. ISO3083:1986, Iron ores Preparation of samples Manual method. ISO77
18、64:1985, Iron ores Preparation of predried test samples for chemical analysis. 3 Principle 3.1 Decomposition of the test portion 3.1.1 Acid decomposition For samples containing not more than0,05%(m/m) of vanadium,0,1%(m/m) of molybdenum or0,1%(m/m) of copper: by treatment with hydrochloric acid, fil
19、tration of the residue, ignition, treatment with hydrofluoric and sulfuric acids, fusion with potassium pyrosulfate, leaching of the melt and combination with the main iron solution. 3.1.2 Fusion-acidification For samples containing not more than0,05% (m/m) of vanadium,0,1% (m/m) of molybdenum or0,1
20、%(m/m) of copper: by fusion with alkali, leaching of the cold melt with water and acidification with hydrochloric acid. 3.1.3 Fusion-filtration For samples containing more than0,05%(m/m) of vanadium and/or0,1%(m/m) of molybdenum but not more than0,1%(m/m) of copper: by fusion with alkali, leaching o
21、f the cold melt with water followed by filtration. Dissolution of the precipitate in hydrochloric acid. 3.2 Titration of iron Reduction of the major portion of the iron(III) by tin(II) chloride and reduction of the remainder of the iron(III) by titanium(III) chloride. Oxidation of the excess reducta
22、nt with either dilute potassium dichromate solution (method1) or dilute perchloric acid (method2). Titration of the reduced iron with potassium dichromate solution using sodium diphenylaminesulfonate indicator. 4 Reagents During the analysis, use only reagents of recognized analytical grade, and onl
23、y distilled water or water of equivalent purity. Method 4.1 Potassium pyrosulfate (K 2 S 2 O 7 ), fine powder. 1 and2 4.2 Sodium carbonate (Na 2 CO 3 ), anhydrous, or pre-ignited at500 C. 1 and2 4.3 Sodium peroxide (Na 2 O 2 ), dry powder. 1 and2 NOTESodium peroxide should be stored as dry as possib
24、le andshould not be used once it has begun to agglomerate. 4.4 Hydrochloric acid, 1,16g/ml to1,19g/ml. 1 and2 4.5 Hydrochloric acid, 1,16g/ml to1,19g/ml, diluted1+1. 1 and2 4.6 Hydrochloric acid, 1,16g/ml to1,19g/ml, diluted1+10. 2 4.7 Hydrochloric acid, 1,16g/ml to1,19g/ml, diluted1+50. 1 and2 4.8
25、Hydrofluoric acid, 40%(m/m) ( 1,13g/ml) or48%(m/m) ( 1,19g/ml). 1 and2 4.9 Sulfuric acid, 1,84g/ml. 1 and2 4.10 Sulfuric acid, 1,84g/ml, diluted1+1. 1 and2 Carefully pour1 volume of reagent4.9 into1 volume of cold water. 1 and2 4.11 Orthophosphoric acid, 1,7g/ml. 1 and2BS7020-4.2:1990 2 BSI 10-1999
26、5 Apparatus NOTEThe pipette and volumetric flask specified shall conform with ISO648 and ISO1042 respectively. Ordinary laboratory apparatus, and 5.1 Zirconium or vitreous carbon crucible, capacity25ml to30ml. 5.2 Burette, class A, conforming with ISO385-1. 5.3 Platinum crucible Platinum crucibles s
27、hould be precleaned, before use, to avoid iron contamination. 5.4 Weighing spatula of a non-magnetic material or demagnetized stainless steel. 5.5 Muffle furnace, suitable for operation in the range500 C to800 C. Method 4.12 Perchloric acid, 72%(m/m) ( 1,7g/ml), diluted1+1. 2 4.13 Sulfuric acid-orth
28、ophosphoric acid mixture 1 and2 Pour150ml of orthophosphoric acid(4.11) intoabout400ml of water while stirring, add150ml of sulfuric acid(4.9). Cool in a waterbath and dilute with water to1litre. 4.14 Sodium hydroxide (NaOH) solution,20g/l. 1 and2 4.15 Hydrogen peroxide (H 2 O 2 ),30%(V/V) solution.
29、 1 and2 4.16 Hydrogen peroxide (H 2 O 2 ),3%(V/V) solution. 1 Dilute1 volume of reagent4.15 with9 volumesofwater. 4.17 Potassium permanganate (KMnO 4 ) solution,25g/l. 1 and2 4.18 Potassium dichromate (K 2 Cr 2 O 7 ) solution,0,5g/l. 1 4.19 Tin(II) chloride solution, 100g/l. 1 and2 Dissolve100g of c
30、rystalline tin(II) chloride (SnCl 2 2H 2 O) in200ml of hydrochloric acid(4.4)byheating the solution in a water bath.Cool the solution and dilute with water to1litre. This solution should be stored in a brownglass bottle with a small quantity of granular tin metal. 4.20 Titanium(III) chloride (TiCl 3
31、 ) solution,15g/l 1 and2 Dilute1 volume of titanium(III) chloride solution(about15% TiCl 3 ) with9 volumes ofhydrochloric acid (4.5). Alternatively, dissolve1gof titanium sponge in about30mlofhydrochloric acid(4.4) in a coveredbeaker, by heating in a water bath. Coolthesolution and dilute with water
32、 to200ml.Prepare fresh solution as needed. 4.21 Iron, standard solution,0,1mol/l. 1 and2 Transfer5,58g of pure iron to a500ml Erlenmeyerflask and place a small filter funnelinthe neck. Add75ml of hydrochloric acid(4.5) in small increments and heat until dissolved. Cool and oxidize with5ml of hydroge
33、nperoxide(4.15) added in small portions.Heat to boiling and boil to decomposetheexcess hydrogen peroxide and toremove chlorine. Transfer to a1000ml volumetric flaskand dilute to volume. Method 1,00ml of this solution is equivalent to1,00mlofthe standard potassium dichromatesolution. 4.22 Potassium d
34、ichromate (99,9%minimum purity), standard solution,0,01667mol/l. 1 and2 Pulverize about6g of potassium dichromate reagent in an agate mortar, dryat140 C to150Cfor2h, and cool to room temperatureinadesiccator. Dissolve4,904g of this material in water, transferto a1000ml volumetric flask, makeuptovolu
35、me with water after cooling to20Candmix. NOTE 1The volumetric flask should previously be calibratedbyweighing the mass of water contained at20Candconverting to volume. NOTE 2Record the temperature at which this dilution wasmade(20 C) on the stock bottle. 4.23 Indigo carmine indigo-5,5-disulfonic aci
36、d disodium salt (C 16 H 8 O 8 N 2 S 2 Na 2 ) solution,0,1g/100ml. 1 Dissolve0,1g of indigo carmine in a cold mixtureof50ml sulfuric acid(4.10) and50mlofwater. 4.24 Sodium diphenylaminesulfonate indicator, solution,0,2g/100ml. 1 and2 Dissolve0,2g of sodium diphenylaminesulfonate (C 6 H 5 NHC 6 H 4 SO
37、 3 Na) inasmall volumeofwaterand dilute to100ml. Store the solution in a brown glass bottle.BS7020-4.2:1990 BSI 10-1999 3 6 Sampling and samples 6.1 Laboratory sample For analysis, use a laboratory sample of less than1004m particle size which has been taken in accordance with ISO3081 or ISO3082 and
38、prepared in accordance with ISO3082 or ISO3083. In the case of ores with significant contents of combined water or oxidizable compounds, use a particle size of less than1604m. NOTE 1A guideline on significant contents of combined water and oxidizable compounds is incorporated in ISO7764. NOTE 2If th
39、e determination of total iron relates to a reducibility test, prepare the laboratory sample by crushing and pulverizing, to less than1004m particle size, the whole of one of the reducibility test portions which has been reserved for chemical analysis. In the case of ores with significant contents of
40、 combined water or oxidizable compounds, use a particle size of less than1604m. 6.2 Preparation of test samples Depending on the ore type, proceed in accordance with either6.2.1 or6.2.2. 6.2.1 Ores with significant contents of combined water or oxidizable compounds Prepare an air-equilibrated test s
41、ample in accordance with ISO2596 with the following types of ores: a) processed ores containing metallic iron; b) natural or processed ores in which the sulfur content is higher than0,2%(m/m); c) natural or processed ores in which the content of combined water is higher than2,5%(m/m). 6.2.2 Ores out
42、side the scope of6.2.1 Prepare a predried test sample as follows. Thoroughly mix the laboratory sample and, taking multiple increments, extract a test sample in such a manner that it is representative of the whole contents of the container. Dry the test sample at105 C 2 C as specified in ISO7764. (T
43、his is the predried test sample.) 7 Procedure 7.1 Number of determinations Carry out the analysis at least in duplicate in accordance withAnnex A, independently, on one test sample(6.2). NOTEThe expression “independently” means that the second and any subsequent result(s) is(are) not affected by the
44、 previous result(s). For this particular analytical method, this condition implies that the repetition of the procedure should be carried out either by the same operator at a different time, or by a different operator, including appropriate recalibration in each case. 7.2 Blank test and check test I
45、n each run, one blank test and one analysis of a certified reference material of the same type of ore shall be carried out in parallel with the analysis of the ore sample(s) under the same conditions. A test sample of the certified reference material shall be prepared in the manner appropriate to th
46、e type of ore involved (see6.2). (Seenote1 below.) 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 o
47、n several samples of the same type of ore at the same time, the analytical value of one certified reference material may be used. NOTE 1The 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 e
48、nsure that in both cases no significant changes in the analytical procedure would become necessary. NOTE 2The certified reference material is used only to validate the performance of the analytical procedure and expressly not to standardize the potassium dichromate solution. 7.3 Determination of hyg
49、roscopic moisture content When the ore type conforms to the specifications of6.2.1, determine the hygroscopic moisture content in accordance with ISO2596, simultaneously with the taking of the test portion(7.4) for the determination of the iron content. 7.4 Test portion Taking several increments, weigh to the nearest0,0002g, approximately0,4g of the test sample(6.2) using a non-magnetic spatula(5.4). NOTE 1For samples with an iron content higher than68%(m/m), weigh approximately0,38g. NOTE 2When predried test samp
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