GB/T 6730.61-2022Iron ores—Determination of carbon and sulfur content—High frequency combustion with infrared absorption method (English PDF)

Foreword

This document was drafted in accordance with the rules provided in GB/T 1.1-2020 Directives for Standardization - Part 1: Rules for the Structure and Drafting of Standardizing Documents.

This document is Part 61 of GB/T 6730 Iron Ores. The parts of GB/T 6730 that have been issued are shown in Appendix A.

This document serves as a replacement of GB/T 6730.61-2005 Iron Ores - Determination of Carbon and Sulfur Content - High Frequency Combustion with Infrared Absorption Method. In comparison with GB/T 6730.61-2005, apart from structural adjustments and editorial modifications, the main technical changes are as follows.

a) Compound flux is added (see 5.3);

b) The requirements in "Sampling and Sample Preparation" are modified (see Chapter 7; Chapter 6 of Version 2005);

c) The stipulations of "sampling size" are modified (see 8.2; 7.2 of Version 2005);

d) The addition mode of compound flux is added (see 8.3 and 8.4);

e) The result calculation and its presentation are modified (see Chapter 9; Chapter 8 of Version 2005).

Please be noted that certain content of this document may involve patents. The institution issuing this document does not undertake the responsibility of identifying these patents.

1 Scope

This document specifies the determination of carbon and sulfur content in iron ore by high frequency combustion with infrared absorption method.

This document is applicable to the determination of carbon and sulfur content in natural iron ore, iron ore concentrate, sinter, pellets and their products. The determination range (mass fraction) is. carbon 0.01% ~ 2.5%, sulfur 0.001% ~ 2.0%.

2 Normative References

The contents of the following documents constitute indispensable clauses of this document through the normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document.

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 6730.3 Iron Ores - Determination of Hygroscopic Moisture in Analytical Samples - Gravimetric, Karl Fischer and Mass-loss Methods

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 12806 Laboratory Glassware - One-mark Volumetric Flasks

GB/T 12807 Laboratory Glassware - Graduated Pipettes

GB/T 12808 Laboratory Glassware - One-mark Pipettes

3 Terms and Definitions

This document does not have terms or definitions that need to be defined.

4 Principle

The specimen is heat and burned in the oxygen flow of a high-frequency induction furnace, and the generated carbon dioxide (or carbon monoxide) and sulfur dioxide are carried by oxygen to the measurement chamber of the infrared analyzer.

5 Reagents and Materials

Unless it is otherwise specified in analysis, use only approved reagents of analytical purity and Grade-2 water specified in GB/T 6682 or water of equivalent purity.

5.1 Magnesium perchlorate. anhydrous, particle size. 0.7 mm ~ 1.2 mm.

5.2 Caustic soda asbestos. granular.

5.5 Tin particles. carbon content (mass fraction) less than 0.002%, sulfur content (mass fraction) less than 0.0005%. If necessary, use acetone (see 5.6) to clean the surface and dry at room temperature.

5.6 Acetone. the carbon content (mass fraction) in the evaporated residue is less than 0.005%.

5.7 Pure iron flux. carbon content (mass fraction) less than 0.002%, sulfur content (mass fraction) less than 0.0005%.

5.10 Sulfur standard solution. in accordance with Table 1, weigh-take potassium sulfate, accurate to 0.0002 g. After using distilled water to dissolve it, transfer it to a 50 mL volumetric flask, dilute to the mark and shake it well.

5.11 Oxygen. purity greater than 99.5%.

5.12 Power gas source. nitrogen, argon or compressed air, and the impurity (water and oil) contents are less than 0.5%.

5.13 Tin tube. with a capacity of 0.3 mL, a diameter of 5 mm and a length of 17 mm.

6 Instruments and Equipment

Unless otherwise specified in the analysis, the used common laboratory instruments, one-mark volumetric flasks, graduated pipettes and one-mark pipettes shall respectively comply with the stipulations of GB/T 12806, GB/T 12807 and GB/T 12808.

6.2 Infrared carbon and sulfur analyzer, with a sensitivity of 1 x 10^-6, including the following parts.

6.3 Ceramic crucible, with precise assembly dimensions, is suitable for the support column, so that it can be lifted to an accurate height in the induction coil; fire at above 1,000 °C for 2 h in Sulfur Standard Solution

6.4 Air source, including the following parts.

6.5 High-frequency induction furnace, which shall satisfy the requirements for the melting temperature of specimen.

6.6 Control system, including the following parts.

6.7 Measuring system, which is mainly composed of a balance (with a sensitivity of less than 1.0 mg), infrared analyzer and electronic measuring component, etc.

6.1 Micropipette (micro-syringe), with a capacity of 50 µL

7 Sampling and Sample Preparation

8 Analytical Procedures

WARNING---during the analysis process, prevent burns and discharge the oxygen released from the burning specimen to the outside of the laboratory to prevent the local oxygen concentration from being too high to catch fire. Perform high frequency shielding to effectively avoid radiation hazards.

9 Result Calculation and Presentation