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1、INTERNATIONAL STANDARD IS0 2598-2 First edition 1992-12-15 Iron ores - Determination of silicon content - Part 2: Reduced molybdosilicate spectrophotometric method Minerais de fer - Dosage du silicium - Parfie 2: Mkfhode specfrophofom m is the mass, in grams, of the test portion. 8.2 General treatme
2、nt of result 8.2.1 Repeatability and permissible tolerance The precision of this analytical method is expressed by the following regression equations? r= 0,020 9 X+ 0,014 8 . * . (2) P=O,O26 4 X+0,115 1 . I . (3) ur = 0,007 4 x + 0,005 2 . . . (4) uL = 0,007 8 X+ 0,041 7 . . , (5) where X is the sil
3、icon content, expressed as a percentage by mass, of the predried test sample, calculated as follows: - within-laboratory equations (2) and (4): the arithmetic mean of the dupli- cate values, - between-laboratories equations (3) and (5): the arithmetic mean of the final result (8.2.3) of the two labo
4、ra- tories; r is the permissible tolerance within a lab- oratory (repeatability); P Is the permissible tolerance between laboratories: ur is the within-laboratory standard devi- ation; OL is the between-laboratories standard de- viation. 8,2.2 Acceptance of analytical values The result obtained for
5、the certified reference ma- terial shall be such that the difference between this result and the certified value of the reference ma- terial is statistically insignificant. For a reference material that has been analysed by at least 10 lab- oratories using method(s) that are comparable both in accur
6、acy and in precision with this method, the following condition shall be used to test the signifi- cance of the difference: I -2 J 2 SWC I Is the average number of replicate de- terminations in the certifying labora- tories; is the number of certifying laboratories; 1) Additional information is given
7、 in annexes B and C. 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Defense Supply Ctr/9960866100 Not for Resale, 04/24/2007 10:16:25 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2598-2:1992(E) n is the numb
8、er of replicate determinations The arithmetic mean of the acceptable analytical on the reference material (in most cases values, calculated to the fourth decimal place, is n = 1); rounded off to the second decimal place as follows: oL and cr are as defined in 8.2.1. If condition (6) is satisfied, i.
9、e. if the left-hand side is less than or equal to the right-hand side, then the difference j A, - A j is statistically insignificant; otherwise, it is statistically significant. When the difference is significant, the analysis shall be repeated, simultaneously with an analysis of the test sample. If
10、 the difference is again significant, the procedure shall be repeated using a different certi- fied reference material of the same type of ore. When the range of the two values for the test sample is outside the limit for r calculated according to equation (2) in 6.2.1, one or more additional tests
11、shall be carried out in accordance with the flowsheet presented in annex A, simultaneously with an analysis of a certified reference material of the same type of ore. Acceptability of the results for the test sample shall in each case be subject to the acceptability of the results for the certified
12、reference material. NOTE 12 The following procedure should be used when the information on the reference material certificate is incomplete: a) when the figure in the third decimal place is less than 5, it is discarded and the figure in the sec- ond decimal place is kept unchanged; b) when the figur
13、e in the third decimal place is 5 and there is a figure other than 0 in the fourth decimal place, or when the figure in the third decimal place is greater than 5, the figure in the second decimal place is increased by one; c) when the figure in the third decimal place is 5 and the figure 0 is in the
14、 fourth decimal place, the 5 is discarded and the figure in the second deci- mal place is kept unchanged if it is 0, 2, 4, 6 or 8 and is increased by one if it is 1, 3, 5, 7 or 9. 8.3 Oxide factor The oxide factor is given by the following equation: WSiO, (%) = 2,139 Wsi (%) 9 Test report The test r
15、eport shall include the following infor- mation: a) if there are insufficient data to enable the between- laboratories standard deviation to be estimated, de- lete the expression s a) name and address of the testing laboratory; b) date of issue of the test report; b) if the certification has been ma
16、de by only one labora- tory or if the interlaboratory results are missing, it is advisable that this material not be used in the appli- cation of the standard. In case its use is unavoidable, use the condition J-77 IA,-A G2 2a,+, . . . (7) 8.2.3 Calculation of final result The final result is the ar
17、ithmetic mean of the ac- ceptable analytical values for the test sample, or as otherwise determined by the operations specified in annex A. c) reference to this part of IS0 2598; d) details necessary for the identification of the sample; e) results of the analysis: f) reference number of the result;
18、 a) anv characteristics noticed during the determi- WI . nation, and any operations not specified in this part of IS0 2598 which may have had an influ- ence on the result, for either the test sample or the certified reference material(s). 5 Copyright International Organization for Standardization Pr
19、ovided by IHS under license with ISO Licensee=Defense Supply Ctr/9960866100 Not for Resale, 04/24/2007 10:16:25 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2598-2:1992(E) Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for test
20、 samples I -x1,x2 I r- r- I I I I IX1 IX1 - x21 - x21 I I I I c c l- l- - - IN0 11 Perfomx x4 Range of xl, x2, xg x4 1,3 r r= Xl f x2 -I- x3 + x4 4 F = Median of xl, x2, xs x4 r: as defined in 8.2.1 6 Copyright International Organization for Standardization Provided by IHS under license with ISO Lic
21、ensee=Defense Supply Ctr/9960866100 Not for Resale, 04/24/2007 10:16:25 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2598-2:1992(E) Annex B (informative) Derivation of repeatability and permissible tolerance equations The equations in 8.2.1 were derived from the resu
22、lts of international analytical trials carried out in 1970 and 1971 on five iron ore samples, involving 33 laboratories in 12 countries. Graphical treatment of the precision data is given in annex C . The test samples used are listed in table B.I. NOTES 13 A report of the international trials and a
23、statistical analysis of the results (Document lSO/TC 102/SC 2 N 225, June 1971) are available from either the Secretariat of ISO/TC 102/SC 2 or the Secretariat of lSO/TC 102. 14 The statistical analysis was performed in accordance with the principles embodied in IS0 57251986, Precision of test metho
24、ds - Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. Table B.1 - Silicon contents of test samples Silicon content Sample % (m/m) Palabora ore Philippine iron sand Swedish ore UK slnter Krivoi Rog ore 0,20 I,06 395 7,85 12,95 - 7 Copyright Inte
25、rnational Organization for Standardization Provided by IHS under license with ISO Licensee=Defense Supply Ctr/9960866100 Not for Resale, 04/24/2007 10:16:25 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2598-2:1992(E) Annex C (informative) Precision data obtained by i
26、nternational analytical trials NOTE 15 FigureC.l is a graphical representation of the equations in 8.21. 0,5 0,4 0.3 i3 s I g On2 081 0 0 A” += X I I I I I I I I 0 2 4 6 tl 10 12 14 Slllcon tontent t % (m/m 13 Figure Cl - Least-squares fit of precision against X for silicon Copyright International O
27、rganization for Standardization Provided by IHS under license with ISO Licensee=Defense Supply Ctr/9960866100 Not for Resale, 04/24/2007 10:16:25 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 2598-2:1992(E) UDC 533.31:543.42:546.28 Descriptors: minerals and ores, iron
28、 ores, chemical analysis, determination of content, silicon, spectrometric method, test results. Price based on 8 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Defense Supply Ctr/9960866100 Not for Resale, 04/24/2007 10:16:25 MDTNo reproduction or networking permitted without license from IHS -,-,-