ISO 2597-2:2015

ISO 2597-2:2015 pdf free.Iron ores – Determination of total iron content – Part 2: Titrimetric methods after titanium(III) chloride reduction.
3 Principle
3.1 Decomposition of the test portion
3.1.1 Acid decomposition
For samples containing not more than 0,05 % mass fraction of vanadium, the test portion is treated with hydrochloric acid in the presence of tin chloride.
The residue is filtered, ignited and treated with hydrofluoric and sulfuric acids. The mixture is fused with potassium disulfate and the cold melt is dissolved in water more hydrochloric acid and combined with the main iron solution, which is treated with potassium permanganate and evaporated.
3.1.2 Fusion-filtration
For samples containing more than 0,05 % mass fraction of vanadium, the test portion is fused with a mixture of fluxes, the cold melt is leached with water and the precipitate is filtered, washed in sodium hydroxide solution, dissolved in hydrochloric acid and evaporated.
3.2 Titration of iron
The major portion of the iron(III) is reduced by tin(II) chloride and the remainder of the iron(IlI) is reduced by titanium(III) chloride. The excess reductant is oxidized with either dilute potassium dichromate solution. The reduced iron is titrated with potassium dichromate solution using the sodium diphenylaminesulfonate indicator.
7 Procedure
7.1 Number of determinations
Carry out the analysis, at least in duplicate, in accordance with Annex A, independently, on one test sample (see 6.2).
NOTE The expression “independently” means that the second and any subsequent result(s) is (are) not affected by the previous result(s). For this particular analytical method, this condition implies that the repetition of the procedure is to be carried out either by the same operator at a different time, or by a different operator, including appropriate recalibration in either case.
7.2 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 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 the type of ore involved (see 6.2 and NOTE 1 below.).
Where 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.
Where 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.
NOTE 1 The certified reference material is of the same type as the sample to be analysed and the properties of the two materials are sufficiently similar to ensure that in either case no significant changes in the analytical procedure will be necessary.
NOTE 2 The 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 hygroscopic moisture content
Where the ore type conforms to the specifications of 6.2.2, determine the hygroscopic moisture content in accordance with ISO 2596, simultaneously with the taking of the test portion (see 7.4) for the determination of the iron content.
7.4 Test portion
Taking several increments, weigh to the nearest 0,000 2 g, approximately 0,4 g of the test sample (see 6.2), using a non-magnetic spatula (53). NOTE For samples having an iron content higher than 68 % mass fraction, weigh approximately 0,38 g. Where the ore type is outside the scope of 6.2.2, transfer the portion to a weighing bottle and determine the mass of the test portion to the nearest 0,000 2 g in accordance with the Japanese weighing method (see Annex B).ISO 2597-2 pdf download.

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