1、BRITISH STANDARD BS 7020-11.2: 1993 ISO 9684:1991 Analysis of iron ores Part 11: Methods for the determination of vanadium content Section 11.2 Flame atomic absorption spectrometric method UDC 553.31:543.422:546.881BS7020-11.2:1993 This British Standard, having been prepared under the directionof th
2、e Iron and Steel Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15October 1993 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference ISM/58 Draft for comment 89/47024 DC ISBN 0 580 22296 9 Committ
3、ees responsible for this British Standard 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 Coopt
4、ed members The following body was also represented in the drafting of the standard, through subcommittees and panels: British Ceramic Research Ltd. Amendments issued since publication Amd. No. Date CommentsBS7020-11.2:1993 BSI 07-1999 i Contents Page Committees responsible Inside front cover Nationa
5、l foreword ii 1 Scope 1 2 Normative references 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 6 Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for test samples 7 Annex B (informative) D
6、erivation of repeatability and permissible tolerance equations 8 Annex C (informative) Precision data obtained by international analytical trials 8 Figure C.1 Least-squares fit of precision against X for vanadium (Method 1) 8 Figure C.2 Least-squares fit of precision against X for vanadium (Method 2
7、) 9 Table B.1 Vanadium content of test samples 8 List of references Inside back coverBS7020-11.2:1993 ii BSI 07-1999 National foreword This Section of BS 7020 has been prepared under the direction of the Iron and Steel Standards Policy Committee and is identical with ISO 9684:1991 Iron ores Determin
8、ation of vanadium content Flame atomic absorption spectrometric method, published by the International Organization for Standardization (ISO). Cross-references The Technical Committee has reviewed the provisions of ISO 648, to which normative reference is made in the text, and has decided that they
9、are acceptable for use in conjunction with this standard. A related British Standard to ISO648:1977 is BS 1583:1986 Specification for one-mark pipettes. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their cor
10、rect application. Compliance with a British Standard does not of itself confer immunity from legal obligations. International standard Corresponding British Standard ISO 1042:1983 BS 1792:1982 Specification for one-mark volumetric flasks (Identical) BS 5660 Methods of sampling iron ores ISO 3081:198
11、6 Part 1:1987 Manual method of increment sampling (Identical) ISO 3082:1987 Part 2:1987 Mechanical method of increment sampling and sample preparation (Identical) ISO 3083:1986 BS 5661:1987 Method for preparation of samples of iron ores by manual means (Identical) ISO 7764:1985 BS 7020 Analysis of i
12、ron ores Part 1:1988 Method for the preparation of pre-dried test samples for chemical analysis (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 10, an inside back cover and a back cover. This standard has been updated (see copyrigh
13、t date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.ISO9684:1991(E) BSI 07-1999 1 1 Scope This International Standard specifies two flame atomic absorption spectrometric methods for the determination of the vanadium content of iro
14、n ores. Method 1 is applicable to vanadium contents between 0,005% (m/m) and 0,05% (m/m), and Method 2 to vanadium contents between 0,05% (m/m) and 0,5% (m/m) in natural iron ores, iron ore concentrates and agglomerates, including sinter products. 2 Normative references The following standards conta
15、in provisions which, through reference in this text, constitute provisions of this International 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 investigat
16、e the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 648:1977, Laboratory glassware One-mark pipettes. ISO 1042:1983, Laboratory glassware One-mark volumetric flasks. ISO 308
17、1:1986, Iron ores Increment sampling Manual method. ISO 3082:1987, Iron ores Increment sampling and sample preparation Mechanical method. ISO 3083:1986, Iron ores Preparation of samples Manual method. ISO 7764:1985, Iron ores Preparation of predried test samples for chemical analysis. 3 Principle 3.
18、1 Dissolution Decomposition of the test portion by digestion with hydrochloric acid in a polytetrafluoroethylene (PTFE) beaker, addition of hydrofluoric and nitric acids and evaporation to dryness. Addition of hydrochloric and boric acids and evaporation to dryness. Dissolution of the salts in hydro
19、chloric and nitric acids (Method 1), or hydrochloric acid (Method2), and filtration. Ignition and fusion of the residue with sodium carbonate and dissolution of the cooled melt in the test solution. 3.2 Determination 3.2.1 Extraction (Method 1 only) Oxidation with cerium(IV) solution and addition of
20、 orthophosphoric acid and sodium tungstate solution. Extraction of the vanadium complex with a1 + 1 mixture of 1-pentanol and methyl isobutyl ketone. Treatment of the solvent phase with water and then ascorbic acid solution to return the vanadium to an aqueous phase. 3.2.2 Measurement (Methods 1 and
21、 2) Addition of aluminium solution to the test solution and dilution to volume. Aspiration into a dinitrogen oxide-acetylene flame in an atomic absorption spectrometer and measurement of the absorbance at a wavelength of approximately 318,5 nm. 4 Reagents During the analysis, use only reagents of re
22、cognized analytical grade, and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid, 1,16 g/ml to 1,19 g/ml. 4.2 Hydrochloric acid, 1,16 g/ml to 1,19 g/ml, diluted 1 + 1. 4.3 Hydrofluoric acid, 1,13 g/ml, 40% (m/m), or 1,19 g/ml, 48 % (m/m). 4.4 Nitric acid, 1,4 g/ml. 4.5 Nitric
23、 acid, 1,4 g/ml, diluted 1 + 1. (Method 1 only.) 4.6 Orthophosphoric acid, 1,7 g/ml, diluted 1 + 2. (Method 1 only.) 4.7 Sodium carbonate (Na 2 CO 3 ), anhydrous powder. 4.8 Boric acid (H 3 BO 3 ). 4.9 Ammoniun cerium(IV) nitrate (NH 4 ) 2 Ce(NO 3 ) 6 , 20 g/l solution. (Method 1 only.) Dissolve 2,0
24、 g of ammonium cerium(IV) nitrate in a mixture of 15 ml of nitric acid (4.5) and 85 ml of water. 4.10 Sodium tungstate (Na 2 WO 4 .2H 2 O), 165 g/l solution. (Method 1 only.) Dissolve 16,5 g of sodium tungstate dihydrate in approximately 70 ml of water, dilute to 100 ml and mix. 4.11 Ascorbic acid (
25、C 6 H 8 O 6 ), 10 g/l solution. (Method 1 only.) Prepare freshly for each series of tests.ISO9684:1991(E) 2 BSI 07-1999 4.12 Pentan-1-ol (n-amyl alcohol, 1-pentanol). (Method 1 only.) 4.13 4-Methylpentan-2-one (methyl isobutyl ketone, MIBK). (Method 1 only.) 4.14 Mixed solvent. (Method 1 only.) Prep
26、are a 1 + 1 volume ratio mixture of pentan-1-ol (4.12) and MIBK (4.13). 4.15 Aluminium chloride (AlCl 3 .6H 2 O), 220 g/l solution. Dissolve 220 g of aluminium chloride hexahydrate in water, add 50 ml of hydrochloric acid (4.1), dilute to 1 000 ml with water and mix. 4.16 Iron oxide, high purity (co
27、ntaining less than0,002% V). 4.17 Iron background solution. (Method 2 only.) Dissolve 90 g of high purity iron oxide (4.16) in750ml of hydrochloric acid (4.1) while heating. Cool and carefully add a solution of 30 g of sodium carbonate (4.7) in 200 ml of water. Dilute with water to a final volume of
28、 approximately 1 000 ml and mix. NOTE 1The use of an equivalent quantity of metallic iron (of similarly low vanadium content) in conjunction with a suitable oxidant is permissible. 4.18 Vanadium standard solution, 1 mg V/ml. Dry ammonium monovanadate (NH 4 VO 3 ) in an air oven at 100 C for 1 h and
29、cool to room temperature. Dissolve 2,296 g of the dried product in approximately 600 ml of water, transfer to a1000ml one-mark volumetric flask, dilute to volume with water and mix. 4.19 Diluted vanadium standard solution, 0,2 mg V/ml. (Method 1 only.) Transfer 20,0 ml of vanadium standard solution(
30、4.18) to a 100 ml one-mark volumetric flask, dilute to volume with water and mix. 4.20 Vanadium calibration solutions. (Method 1 only.) Transfer 1,8 g of high purity iron oxide (4.16) to each of five 100 ml PTFE beakers (5.1). Proceed according to 7.5.1, incorporating the operation in 7.5.2 to disso
31、lve the evaporated salts. Transfer 0 ml; 1,00 ml; 2,00 ml; 4,00 ml and 6,00 ml of the diluted standard vanadium solution (4.19) respectively to the beakers. Omit the residue processing steps and add 10 ml of nitric acid (4.5) and 25 ml of water. Evaporate to 50 ml and proceed as specified in 7.5.3.
32、4.21 Vanadium calibration solutions. (Method 2 only.) Transfer 0 ml; 1,00 ml; 2,00 ml; 4,00 ml and 6,00 ml of vanadium standard solution (4.18) respectively to five 100 ml one-mark volumetric flasks. Add 10 ml of iron background solution (4.17), 4,0 ml of aluminium chloride solution (4.15) and 0,5 g
33、 of boric acid (4.8) to each flask. Dilute to volume with water and mix. 5 Apparatus Ordinary laboratory equipment, including one-mark pipettes and one-mark volumetric flasks complying with the specifications of ISO 648 and ISO 1042 respectively (unless otherwise indicated), and 5.1 Polytetrafluoroe
34、thylene (PTFE) beakers, of capacity 100 ml, preferably low form. 5.2 Platinum crucibles, of minimum capacity 20 ml. 5.3 Muffle furnace 5.4 Separating funnels, 100 ml (preferablygraduated). 5.5 Atomic absorption spectrometer, equipped with a dinitrogen oxide-acetylene burner. The atomic absorption sp
35、ectrometer used in this method will be satisfactory if it meets the following criteria: a) Minimum sensitivity the absorbance of the most concentrated vanadium calibration solution(4.21) is at least 0,25 (see note 4). b) Graph linearity the slope of the calibration graph covering the top 20% of the
36、concentration range (expressed as a change in absorbance) is not less than 0,7 of the value of the slope for the bottom 20% of the concentration range determined in the same way. c) Minimum stability the standard deviation of the absorbance of the most concentrated calibration solution and that of t
37、he zero calibration solution, each being calculated from a sufficient number of repetitive measurements, are less than 1,5% and 0,5% respectively of the mean value of the absorbance of the most concentrated calibration solution. NOTE 2The use of a strip-chart recorder and/or digital read-out device
38、is recommended to evaluate criteria a), b) and c) and for all subsequent measurements. NOTE 3Instrument parameters The slit width should be sufficiently narrow to substantially reject the stronger emitting but weaker absorbing line at318,4nm. V-hollow cathode lamp, mA Wavelength, nm Dinitrogen oxide
39、 flow rate, l/min Acetylene flow rate, l/min 10 318,5 9,5 3,8ISO9684:1991(E) BSI 07-1999 3 In systems where the values shown above for gas flow rates do not apply, the given ratio of the flow rates (5 : 2) may still be a useful guideline. NOTE 4To check the instrument criteria when only Method 1 is
40、involved, prepare the highest calibration solution specified for Method 2, omitting the iron background solution. 6 Sampling and samples 6.1 Laboratory sample For analysis, use a laboratory sample of minus1004m particle size which has been taken in accordance with ISO 3081 or ISO 3082 and prepared i
41、n accordance with ISO 3082 or ISO 3083. In the case of ores with significant contents of combined water or oxidizable compounds, use a particle size of minus 160 4m. NOTE 5A guideline on significant contents of combined water and oxidizable compounds is incorporated in ISO 7764. 6.2 Preparation of p
42、redried test samples Thoroughly mix the laboratory sample and, taking multiple increments, extract a test sample in such a way that it is representative of the whole contents of the container. Dry the test sample at 105 C 2 C as specified in ISO 7764. (This is the predried test sample.) 7 Procedure
43、7.1 Number of determinations Carry out the analysis at least in duplicate in accordance with Annex A, independently, on one predried test sample. NOTE 6The expression “independently” means that the second and any subsequent result is not affected by the previous result(s). For this particular analyt
44、ical method, this condition implies that the repetition of the procedure shall be carried out either by the same operator at a different time or by a different operator including, in both cases, appropriate recalibration. 7.2 Safety precautions WARNING Follow the manufacturers instructions for ignit
45、ing and extinguishing the dinitrogen oxideacetylene flame to avoid possible explosion hazards. Wear tinted safety glasses whenever the burner is in operation. 7.3 Test portion Taking several increments, weigh, to the nearest0,0005 g, approximately 2 g (Method 1) or1g (Method 2) of the predried test
46、sample obtained in accordance with 6.2. NOTE 7The test portion should be taken and weighed quickly, in order to avoid reabsorption of moisture. 7.4 Blank test and check test In each run, one blank test and one analysis of a certified reference material of the same type of ore shall be carried out in
47、 parallel with the analysis of the ore sample(s) under the same conditions. A predried test sample of the certified reference material shall be prepared as specified in 6.2. NOTE 8The certified reference material should be of the same type as the sample to be analysed and the properties of the two m
48、aterials should be sufficiently similar to ensure that in both cases no significant changes in the analytical procedure will 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
49、 and the reagents used are from the same reagent bottles. When the analysis is carried out on several samples of the same type of ore at the same time, the analytical value of one certified reference material may be used. 7.5 Determination Method 1 vanadium content between 0,005% (m/m) and 0,05% (m/m) 7.5.1 Decomposition of the test portion Transfer the test portion (7.3) to a 100 ml PTFE beaker (5.1) and add 25 ml of hydrochloric acid (4.1). Cover and mix, and then digest just at the boiling point for 1 h. Ad
