BS-6870-2.8-1987 ISO-8556-1986.pdf
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1、BRITISH STANDARD BS 6870-2.8: 1987 ISO 8556:1986 Analysis of aluminium ores Part 2: Chemical methods Section 2.8 Method for determination of phosphorus content: spectrophotometric method ISO title: Aluminium ores Determination of phosphorus content Molybdenum blue spectrophotometric method UDC 553.4
2、92:543 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:53:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6870-2.8:1987 This British Standard, having been prepared under the direction of the Non-ferrous Metals Standards Committee, was published under the authority of the Board of BSI and
3、comes into effect on 28 August 1987 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference NFM/31 Draft for comment 84/42594 DC ISBN 0 580 16061 0 National foreword This Section of BS 6870 has been prepared under the direction of the Non-ferrous Metals Stan
4、dards Committee. It is identical with ISO 8556:1986 “Aluminium ores Determination of phosphorus content Molybdenum blue spectrophotometric method”, published by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been appr
5、oved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current p
6、ractice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Section of BS 6870”. Additional information. When adopting the text of the International Standard, it was noticed that in 4.7 hyd
7、rochloric acid with a density of 1.19 g/ml and nitric acid with a density of 1.41 g/ml are specified, whereas in the UK acids with densities of 1.18 g/ml and 1.42 g/ml respectively are normally used. These differences, which will not affect the determination, have been brought to the attention of IS
8、O in a proposal to amend the International Standard by specifying wider ranges for the densities of the hydrochloric acid and nitric acid required. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct
9、application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright
10、 date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Cross-reference International StandardCorresponding British Standard ISO 8558:1985BS 6870 Analysis of aluminium ores Section 2.1:1987 Method of preparation of pre-dried test samp
11、les (Identical) Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:53:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6870-2.8:1987 BSI 01-2000i Contents Page National forewordInside front cover 1Scope and field of application
12、1 2Reference1 3Principle1 4Reagents1 5Apparatus1 6Sampling and samples2 7Procedure2 8Expression of results4 9Test report5 Annex Flowsheet of the procedure for the acceptance of test results6 Table 1 Aliquot portions of test solution required3 Table 2 Precision data for phosphorus determinations5 Pub
13、lication referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:53:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:53:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6870-2.8:1987 BSI 01-20001 1 Scope a
14、nd field of application This International Standard specifies a molybdenum blue spectrophotometric method for the determination of phosphorus in aluminium ores and minerals. The method is applicable to materials having phosphorus contents, expressed as diphosphorus pentoxide between 0,01 and 5 % (m/
15、m). The arsenic content of the sample does not affect the determination. 2 Reference ISO 8558, Aluminium ores Preparation of predried test samples. 3 Principle Decomposition of a test portion, by either a) treatment with a mixture of hydrochloric acid, nitric acid and sulfuric acid; NOTEThis method
16、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 test portion. or b) sintering with sodium peroxide followed by a brief fusion. Dissolution of the melt with sulfuric acid. NOT
17、EThis method is recommended for ores containing Diaspore and when the residue from the dissolution of the test portion is greater than 1 % of the mass of the test portion. Dehydration of silica, dissolution of salts, filtration and ignition of the impure silica. Removal of the silica by evaporation
18、with hydrofluoric and sulfuric acids. Fusion with sodium carbonate and sodium tetraborate, dissolution with hydrochloric acid and combination with the main solution. Addition of molybdate to convert the phosphate to molybdophosphate complex, and reduction to molybdenum blue with ascorbic acid. Spect
19、rophotometric measurement of the absorbance of the molybdenum blue complex at approximately 710 nm. 4 Reagents During the analysis, use only reagents of recognized analytical reagent grade, and only distilled water or water of equivalent purity. 4.1 Sodium peroxide (Na2O2), powder. NOTESodium peroxi
20、de should be protected against humidity and should not be used once it has begun to agglomerate. 4.2 Sodium carbonate/sodium tetraborate flux. Mix intimately 3 parts by mass of anhydrous sodium carbonate (Na2CO3) with 1 part by mass of anhydrous sodium tetraborate (Na2B4O7). 4.3 Sulfuric acid, 201,8
21、4 g/ml, diluted 1 + 1. 4.4 Sulfuric acid, 201,84 g/ml, diluted 1 + 9. 4.5 Hydrofluoric acid, 40 % (m/m) (201,13 g/ml) or 48 % (m/m) (201,18 g/ml). 4.6 Hydrobromic acid, 40 % (m/m) (201,38 g/ml) or 47 % (m/m) (201,48 g/ml). 4.7 Acid mixture Measure into a 1 litre beaker 225 ml water and add cautiousl
22、y, with mixing, 175 ml of sulfuric acid (4.3). Cool well and add 150 ml hydrochloric acid (201,19 g/ml) and 50 ml of nitric acid (201,41 g/ml). Prepare this solution fresh for each series of tests, and discard any unused solution, flushing copiously with water. 4.8 Ascorbic acid (C6H8O6), 2 g/l solu
23、tion. Prepare this solution fresh on the day of use. 4.9 Disodium disulfite (Na2S2O5), 150 g/l solution. Prepare this solution fresh on the day of use. 4.10 Sodium molybdate (Na2MoO4.2H2O), 50 g/l solution. 4.11 Bismuth, solution. Dissolve 4,25 g of bismuth sulfate Bi2(SO4)3 (specification 90 %) or
24、2,80 g of bismuth oxycarbonate (90 % Bi2O3) in 280 ml of sulfuric acid (4.3) and heat until the salt is dissolved completely. Cool to room temperature, transfer to a 1 000 ml one-mark volumetric flask, dilute to the mark with water and mix. 1 ml of this solution contains 2,5 mg of Bi2O3. 4.12 Phosph
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