1、International Standard 6607 INTERNATIONAL ORGANIZATION FORSTANOARDlZATIONWlEYHAPOAHAR OPrAHH3AWlR RO CTAHAAPTH3AUW4*ORGANlSATlON INTERNATIONALE DE NORMALISATION Aluminium ores - Determination of total. silicon content - Combined gravimetric and spectrophotometric method Minerais alumineux - Dosage d
2、u silicium total - Mkhodes gravimetrique et spectrophotom Descriptors : minerals and ores, aluminium ores, chemical analysis, determination of content, silicon, gravimetric analysis, spectrophotometric s analysis. : v, Price based on 5 pages Copyright International Organization for Standardization P
3、rovided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International St
4、andards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, al
5、so take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by
6、the member bodies voting. International Standard IS0 6667 was prepared by Technical Committee ISO/TC 129, Aluminium ores. International Organization for Standardization, 19% 0 Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISONot fo
7、r ResaleNo reproduction or networking permitted without license from IHS-,-,-INTERNATIONAL STANDARD IS0 6607-1985 (E) Aluminium ores - Determination of total silicon content - Combined gravimetric and spectrophotometric method 1 Scope and field of application This International Standard specifies a
8、combined gravimetric method and spectrophotometric method for the determination of the total silicon content in aluminium ores. The method is applicable to ores containing between 1 and 25 % (mlm) of silicon dioxide. 2 References IS0 5725, Precision of test methods - Determination of repeatability a
9、nd reproducibility by intra-laboratory tests. IS0 6995, Aluminium ores - Determination of titanium con- tent - 4,4-Diantipyrylmethane spectrophotometric method. 3 Principle Decomposition of the test portion by either a) Treatment with a mixture of hydrochloric acid, nitric acid and sulfuric acid. NO
10、TE - This method is recommended for ores containing gibbsite and/or boehmite and when the residue from the dissolution of the test portion after silica volatilization is less than 1 % of the mass of the test portion; or b) Sintering with sodium peroxide followed by a brief fu- sion, Dissolution of t
11、he melt with sulfuric acid. NOTE - This method is recommended for ores containing diaspore, and when the residue after silica volatilization for acid decomposition is greater than 1 % of the mass of the test portion. or c) The fusion method given in 3c) and sub-clause 7.5.1.3 of IS0 9995. Dehydratio
12、n of silica, dissolution of salts, filtration and ignition of the impure silica, treatment with hydrofluoric acid and sulfuric acid. Fusion of the residue with sodium car- bonate/sodium tetraborate flux, dissolution of the melt with sulfuric acid and addition to the main solution. Treatment of an al
13、iquot portion of the main solution with ex- cess sodium hydroxide and heating to depolymerize the silica in solution. Acidification with sulfuric acid and adjustment to pH 140, followed by addition of ammonium molybdate. Destruction of molybdophosphoric and molybdoarsenic acids with further sulfuric
14、 acid, reduction of the a-molybdosilicic acid to the blue complex and measurement of the abs.orbance at about 810 nm. 4 Reagents During the analysis, use only reagents of analytical reagent grade and only distilled water or water of equivalent purity. 4.1 Sodium peroxide. NOTE - Sodium peroxide shou
15、ld be protected against humidity and should not be used once it has begun to agglomerate. 4.2 Sodium carbonate/sodium tetraborate flux. Mix 3 parts bymass of anhydrous sodium carbonate and 1 part by mass of anhydrous sodium tetraborate flux. 4.3 Hydrofluoric acid, 40 % (m/m), 20 = I,13 g/ml. 4.4 Sul
16、furic acid, ezo = 194 g/ml, diluted 1 + 1. 4.6 Sulfuric acid, e20 = I g/ml, diluted 1 + 3. 4.6 Sulfuric acid, ezo = I,84 g/ml, diluted 1 + 9. 4.7 Sulfuric acid, ezo = 1, A=T-B m2 is the mass of crucible and contents, in grams, after ignition (7.5.3); 7.7 Calibration m3 is the mass of crucible and co
17、ntents, in grams, after treatment with hydrofluoric acid (7.5.3); Into six separate 150 ml plastics beakers (5.31, pipette 0, 5, 10, 15, 20 and 25 ml aliquot portions respectively of the standard silica solution (4.13) as shown in table 1. Into the same six rn2, is the mass of crucible and contents,
18、 in grams, after ignition for the blank determination; 4 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 6607-1985 (El qb is the mass of crucible and contents, in gra
19、ms, after treatment with hydrofluoric acid for the blank determi- nation; msrog is the mass of silica, in micrograms, obtained from the calibration graph. 8.2 General treatment of results 8.2.1 Precision The precision of this method, as determined in an international test programme, is expressed in
20、terms of repeatability, reproducibility and reproducibility index in table 2. Table 2 - Precision data for silicon determinations Sample MT/1212 MT/12/1 MT/l214 Mean SiO2 Components of Reprodu- content standard deviation cibility index % lmlml r R 2s 13.3 0,035 0,072 0;16 2,57 0,034 0,025 0,085 5m 0
21、,045 0,070 0,17 MT/12/6 21,59 0,059 0,19 0,39 I r is the repeatability; R is the reproducibility. value obtained for the certified reference material is again out- side the limits, the procedure shall be repeated with a different reference material of the same type of ore until two acceptable values
22、 for the test sample are obtained. When the range (absolute difference) of the two values for the test sample is greater than 2,77 r, additional analyses shall be carried out on one test sample with one blank test simultaneously with an analysis of a certified reference material of the same type of
23、ore. Acceptance of such additional values for the test sample shall be subject, in each case, to the accep- tability of the value obtained for the certified reference material. 8.2.3 Calculation of final result The final result is the arithmetical mean of the acceptable analytical values calculated
24、to four decimal places and rounded off to the second decimal place as follows: a) when the figure in the third decimal place is less than 5, it is discarded and the figure in the second decimal place is kept unchanged; b) when the figure in the third decimal place is 5 and there are figures other th
25、an 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 there are no figures other than 0 in the fourth decimal place; the 5 is discarded and
26、the figure in the second decimal place is kept unchanged if it is 0,2,4,6 or 8, and increased by one if it is 1, 3, 5, 7 or 9. 8.2.2 Acceptance of analytical values (see IS0 5725) 9 Test report The analytical value for the test sample shall be accepted when the analytical value obtained for the corr
27、esponding certified reference material agrees with the certified value within the limit of the reproducibility index contained in table 2, and when the difference between the two values for the test sample does not exceed 2,77 r, as calculated from the appropriate value of r given in table 2. When t
28、he analytical value obtained for the certified reference material is outside the reproducibility index, an analysis shall be carried out simultaneously on one test sample and one certified reference material, with one blank test. The analytical value ob- tained for the certified reference material s
29、hall be examined for the acceptance of the value for the test sample, as above. If the The test report shall include the following information : a) details necessary for the identification of the sample; b) reference to this International Standard; cl results of the analysis; d) reference number of
30、the results; e) any characteristics noticed during the determination and any operations not specified in this International Stan- dard which may have had an influence on the results. 5 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
