GB/T 6730.6-2016Iron ores—Determination of metallic iron content—Ferric chloride-sodium acetate titrimetric method (English PDF)

Foreword

GB/T 6730 "Iron ores" consists of several parts.

This Part is Part 6 of GB/T 6730.

This Part was drafted in accordance with the rules given in GB/T 1.1-2009.

This Part replaces GB/T 6730.6-1986 "Methods for chemical analysis of iron ores. The ferric chloride-sodium acetate volumetric method for the determination of metallic iron content".

Compared with GB/T 6730.6-1986, in addition to editorial modifications, the main technical changes are as follows.

- changed the standard's name to "Iron ores - Determination of metallic iron content - Ferric chloride-sodium acetate titrimetric method";

- added the content of "Warning", "Normative references", "Instruments", "Test report", "Annex B" and "Annex C";

- changed the determination range from "0.3%~2.0%" to "0.150%~3.00%";

- modified the processing operation for separating non-magnetic substances and the stirring time of metal iron leaching; changed from outer magnetic separation to inner magnetic separation;

- modified the calculation formula for "calculation of analysis results";

- conducted the interlaboratory precision co-test; used the statistically derived repeatability limits r and reproducibility limits R to replace "tolerance".

1 Scope

This Part of GB/T 6730 specifies the ferric chloride-sodium acetate titrimetric method to determine the metallic iron content.

This Part is applicable to determination of metallic iron content in iron ore, iron concentrate, sinter and pellets. The determination range (mass fraction). 0.150%~3.00%.

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 6379.1, Accuracy (trueness and precision) of measurement methods and results - Part 1: General principles and definitions

GB/T 6379.2, Measurement methods and results - Accuracy (trueness and precision) - Part 2: Determine the standard methods of measurement repeatability and reproducibility of the basic method

GB/T 6682, Water for analytical laboratory use - Specification and test methods

GB/T 6730.1, Iron ores - Preparation of pre-dried test samples for chemical analysis

3 Principle

The specimen is first separated from non-magnetic substances by magnetic separation. Under electromagnetic stirring conditions, use ferric chloride-sodium acetate buffer solution (pH 2.2~2.4) to selectively dissolve metallic iron.

After separation by filtration, use potassium dichromate standard titration solution titrate the filtrate.

4 Reagents

Unless otherwise specified, in the analysis, it shall only use the confirmed analytically-pure reagents and grade three and above distilled water specified in GB/T 6682 or deionized water or equivalent-pure water.

4.1 Anhydrous ethanol.

4.8 Pickled asbestos. Take 10g of pickled asbestos and burn at 900°C for more than 2h in advance. Leave it for future use.

5 Instruments

In the analysis, only common laboratory instruments are used. The burettes, single-marked volumetric flasks and single-marked pipettes used shall comply with the provisions of GB/T 12805, GB/T 12806 and GB/T 12808, respectively.

5.3 Non-magnetic metal iron core stirrer.

5.4 Adjustable speed magnetic stirrer.

6 Sampling and sample preparation

7 Analysis steps

8 Analysis results and their representation

9 Test report

The test report shall contain the following information.

Annex A (Normative)

Acceptance procedure for specimen analysis results See Figure A.1 for the acceptance procedure for specimen analysis results.

Annex B (Informative)

Precision test raw data The precision data is determined by a joint analysis test of 5 iron ore samples by 8 domestic laboratories from 2014 to 2015.The content of metallic iron at each level is determined independently by each laboratory 3 times under repeatable conditions. The determined raw data are shown in Table B.1. […]