1 Scope
This document specifies the determination of scorch reduction in iron ores by the moisture absorption water corrected weight method.
This document applies to natural iron ores, iron ore concentrates and man-made lump iron ores in the determination range (mass fraction): 1.0% to 10.0%. This document does not apply to the following cases:
a) processed iron ores containing metallic iron (direct reduced iron;
b) Natural or processed iron ores with a sulphur content of more than 0.2%;
c) Natural or processed iron ores containing more than 1.0% by mass of ferrous oxide.
2 Normative references
The content of the following documents constitutes an essential provision of the water document through normative references in the text. Among them, note the date of the reference documents, only the date of the corresponding version applies to this document; not note the date of the reference documents, the latest version (including all the revision of the list) applies to this document.
GB/T 6730.1 Preparation of pre-dried marc samples for iron ore analysis (GB/T 6730.1-2016, ISO 7764;2006,MOD)
GB/T 6730.3 Determination of moisture absorption in iron ore analysis samples by weight, Karl Fischer method and mass loss method (GB/T 6730.3-2017,ISO 2596;2006,MOD)
GB/T 8170 Rules for the modification of values and the representation and determination of limit values
GB/T 10322.1 Method for sampling and preparation of iron ore (GB/T 10322.1-2014,ISO 3082;2009,IDT)
3 Terminology and definitions
There are no terms and definitions in this document that need to be defined.
4 Principle
The test material is cauterised at 1 000 °C to a constant weight and cooled in a desiccator. The mass loss of the test material is measured and expressed as a mass fraction relative to the original mass, i.e. the cautery reduction.
5 Reagents
Only approved analytical pure reagents were used during the analysis, unless otherwise stated. Silica gel desiccant, dried at 105°C for 4 h.
6 Apparatus
6.1 Snail (porcelain cyanide or platinum sieve): 15 mL to 25 ml. capacity, with lid. The slurry and its lid should be pre-treated in a muffle furnace at 1 000 °C for 60 min. before use, the slurry and its lid should be stored in a vacuum desiccator (see 6.4). If the platinum slab used for cautery reduction analysis is used for melt melting, the platinum vessels should be cleaned thoroughly to prevent cross-contamination.
6.2 Balance: 0.1 mg sensitivity.
6.3 Muffle furnace: capable of maintaining a temperature of 1 000 °C ± 25 °C and providing sufficient air circulation to prevent water vapour retention.
6.4 Vacuum dryer: 150 mm~250 mm internal diameter with vacuum plug to maintain air pressure balance. The dryer chassis should be made of metal, ceramic or other heat resistant material that will not break when in contact with cyanosis at 1 000 °C. The edges of the dryer should be coated with a small amount of silicone grease or petroleum jelly. 150 g to 200 g of silicone should be replaced daily (see chapter 5). If a platinum cyanotype is used, a metal desiccator sump should not be used.
7 Preparation of laboratory specimens
Samples should be taken and prepared according to GB/T 10322.1. The general sample size should be less than 100 u.m. If the sample contains high levels of water compounds or perishables, the particle size should be less than 160 p.m. If the sample contains high levels of water compounds or perishables, the particle size should be less than 160 p.m.
The high content of chemical water and easy oxide content in accordance with the provisions of GB / T 6730.1.
8 Analysis procedure
8.1 Specimen
Mix laboratory specimens thoroughly (see Chapter 7) and dispense multiple injuries to ensure that each specimen is representative of the laboratory sample. The test material should be air equilibrated.
Air equilibration is carried out by laying the test specimen flat in a tray with a sample layer density of not more than 0.1 g/cm', air equilibrated in a laboratory environment for 2 h and mixed quickly before testing.
8.2 Number of measurements
The same sample shall be measured at least twice independently in accordance with Appendix B.
Note: "Independent" means that the results of the second and any subsequent determinations are not influenced by the results of the previous determinations. For the purpose of this analytical method, this condition means that the same test object is to be independently repeated in the same laboratory, by the same operator, using the same equipment, and according to the same test method, within a short period of time, including appropriate recalibration.
8.3 Determination of moisture absorption
Two parallel test materials should be measured simultaneously, one for the determination of the burn-off and the other for the determination of the moisture absorption, which should be carried out in accordance with GB/T 6730.3.
8.4 Test material quantity
Weigh approximately 2.0 g ± 0.2 g of test material (see 8.1), to an accuracy of 0.000 1 g.
8.5 Measurement
The test material is placed in a covered floor (see 6.1) and placed in a muffle furnace (see 6.3) and cauterised at 1 000 °C - 25 °C for 60 min - 10 min (ensure that there is no loose material in the muffle chamber that could adhere to the cyanoblast). Remove the WB from the muffle furnace, place in the desiccator (see 6.4) and immediately place the lid on the cyanosome and cool to room temperature. Slowly remove the pressure, remove and quickly complete the weighing. This is repeated until the difference in mass after two successive burns does not exceed 0.05% of the initial mass of the test material, using the mass after the last burn as the basis for calculation.
The test material is weighed at the same temperature and speed as the empty snail weighing as far as possible.
9 Calculation of results and their representation
9.1 Calculation of scorch loss
The loss on ignition (LOI) is expressed as a mass fraction and is calculated on a dry basis.
9.2.2 Determination of analytical results
The results of independent repeated measurements were calculated according to equation (2) according to the procedure in Appendix B and compared with the repeatability limit r to determine the final analytical result p.
9.2.3 Inter-laboratory precision
9.2.4 Correctness check
Correctness checks are performed using certified standard samples (CRM) or standard samples (RM) for validation and the final laboratory result (pe) is used for comparison with the standard value (A.) of the CRM or RM, where two possibilities will occur.
9.2.5 Calculation of the final result
The final result is the arithmetic mean of the acceptable analytical values of the specimen, or the value determined by the procedure specified in Appendix B of the Sound, calculated to an accuracy of 0.001% and reported to an accuracy of 0.01%, as specified in GB/T 8170 approximately.
10 Test report
The test report should include the following information:
a) The name and address of the test laboratory;
b) Date of issue of the test report;
c) The number of this document;
d) the necessary details of the specimen itself;
e) the results of the analysis;
f) any unusual characteristics present during the determination and any operations not specified in this document which may have an effect on the analytical results of the specimen or standard sample.
1 Scope
2 Normative references
3 Terminology and definitions
4 Principle
5 Reagents
6 Apparatus
7 Preparation of laboratory specimens
8 Analysis procedure
9 Calculation of results and their representation
10 Test report
