BS ISO 6467:2018 pdf download

BS ISO 6467:2018 pdf download.1 Scope
This document specifies a potentiometric method for the determination of the vanadium content of ferrovanadium.
The method is applicable to vanadium contents between 35,0 % and 85,0 % (mass fraction) in ferrovanadium.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 3713, Ferroalloys — Sampling and preparation of samples — General rules
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 Principle
Dissolution of a test portion with nitric and sulfuric acids. Cold oxidation of the vanadium(IV) to vanadium(V) by a slight excess of potassium permanganate. Destruction of the excess of potassium permanganate by potassium nitrite, the excess of the latter being itself destroyed by urea. Reduction of the vanadium(V) to vanadium(IV) by iron(II) in a potentiometric titration.
5 Reagents
During the analysis, unless otherwise specified, use only reagents of recognized analytical grade and only grade 2 water as specified in ISO 3696.
5.1 Urea.
5.2 Nitric acid, ρ 1,38 to 1,42 g/ml.
5.3 Phosphoric acid.
5.4 Sulfuric acid, ρ approximately 1,84 g/ml, diluted 1 + 1.
Add cautiously, while stirring, 500 ml of sulfuric acid, ρ approximately 1,84 g/ml to 400 ml of water.Cool, dilute to 1 000 ml with water and mix.
5.5 Potassium nitrite, 10 mg/ml solution.
Dissolve 10 g of potassium nitrite in water, dilute to 1 000 ml and mix.
5.6 Potassium permanganate, 6,3 mg/ml.
Dissolve 6,3 g of potassium permanganate in water, made up with water to a volume of 1 000 ml and mix.
5.7 Potassium dichromate, standard solution, C 1 (1/6K 2 Cr 2 O 7 ) = 0,2 mol/l.
Weigh, to the nearest 0,000 5 g, exactly 9,806 4 g of potassium dichromate previously oven‑dried at 105 °C. Dissolve with water in a 1 000 ml volumetric flask. Dilute to the mark and mix.
5.8 Ammonium iron(II) sulphate, standard volumetric solution, C 2 (FeSO 4 (NH 4 ) 2 SO 4 ) ≈ 0,2 mol/l.
5.8.1 Preparation
In a 1 000 ml volumetric flask, dissolve 78,4 g of ammonium iron(II) sulphate (FeSO 4 (NH 4 ) 2 SO 4 .6H 2 O) with 500 ml of warm water. When the dissolution is complete, add 100 ml of the sulfuric acid (5.4), cool,dilute to the mark and mix.