GB/T 6730.26-2017 Iron ores - Determination of fluorine content - Thorium nitrate titrimetric method
Warning: It has been assumed in the drafting of this part that the execution of its provisions is entrusted to appropriately qualified people with practical experience in formal laboratories. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.
1 Scope
This part of GB/T 6730 specifies the thorium nitrate titrimetric method for the determination of fluorine content.
This part is applicable to the determination of fluorine content in natural iron ore, iron ore concentrate, iron ore sinter and pellet, with determination range (mass fraction) of 2.00% to 15.00%.
2 Normative references
The following referenced documents are indispensable for the application 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.
GB/T 601 Chemical reagent - Preparations of reference titration solutions
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 6730.1 Iron ores - Preparation of predried test samples for chemical analysis
GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
GB/T 10322.1 Iron ores - Sampling and sample preparation procedures
GB/T 12805 Laboratory glassware - Burettes
GB/T 12806 Laboratory glassware - One-mark volumetric flasks
GB/T 12808 Laboratory glassware - One-mark pipettes
3 Principle
The test portion is distilled with perchloric acid and phosphoric acid at 130°C–140°C under steam, separating fluorine from coexisting elements. The pH is adjusted to 3.0–3.2, and the fluorine content is determined by titration with a thorium nitrate reference solution using methylthymol blue as the indicator.
4 Reagents and materials
Unless otherwise specified, only recognized analytically pure reagents and distilled water above Grade III specified in GB/T 6682 or water with equivalent purity shall be used.
4.1 Sodium peroxide.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Reagents and materials
5 Apparatus
6 Sampling and sample preparation
7 Analytical procedures
8 Calculation and expression of results
9 Test report
Annex A (Normative) Acceptance procedure for specimen analytical results
