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GB/T 6730.87-2023 English PDF (GBT6730.87-2023)

GB/T 6730.87-2023 English PDF (GBT6730.87-2023)

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GB/T 6730.87-2023: Iron ores - Determination of total iron and other multi-element content - Wavelength dispersive X-ray fluorescence spectrometry (cobalt internal standard method)

This document specifies the use of wavelength dispersive X-ray fluorescence spectrometry (cobalt internal standard method) for the determination of all iron, silicon, aluminum, calcium, magnesium, manganese, titanium, vanadium, phosphorus, copper, lead, chromium, zinc, arsenic, potassium and sulfur content. This document is applicable to the determination of the following elements in iron ore, iron concentrate, sinter and pellets. The measurement range is shown in Table 1. Table 1 -- Measurement range
GB/T 6730.87-2023
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 73.060.10
CCS D 31
Iron ores - Determination of total iron and other multi-
element content - Wavelength dispersive X-ray fluorescence
spectrometry (cobalt internal standard method)
ISSUED ON: AUGUST 06, 2023
IMPLEMENTED ON: MARCH 01, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 4
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Principle ... 6
5 Reagents and materials ... 6
6 Instruments and equipment ... 8
7 Sampling and sample preparation ... 9
8 Preparation of glass pieces ... 9
9 Instrument preparation ... 13
10 Analysis steps ... 13
11 Result calculation and representation ... 17
12 Test report ... 21
Annex A (informative) Parts of GB/T 6730 that have been published ... 22 Annex B (normative) Procedure for acceptance of specimen analysis results ... 27 Annex C (informative) Raw data from precision tests ... 28
Iron ores - Determination of total iron and other multi-
element content - Wavelength dispersive X-ray fluorescence
spectrometry (cobalt internal standard method)
WARNING -- Personnel using this document shall have practical experience in formal laboratory work. This document does not identify all possible security issues. Users are responsible for taking appropriate safety and health measures and ensuring compliance with relevant national regulations.
1 Scope
This document specifies the use of wavelength dispersive X-ray fluorescence spectrometry (cobalt internal standard method) for the determination of all iron, silicon, aluminum, calcium, magnesium, manganese, titanium, vanadium, phosphorus, copper, lead, chromium, zinc, arsenic, potassium and sulfur content.
This document is applicable to the determination of the following elements in iron ore, iron concentrate, sinter and pellets. The measurement range is shown in Table 1. 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 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
GB/T 8170, Rules of rounding off for numerical values and expression and judgement of limiting values
GB/T 10322.1, Iron ores - Sampling and sample preparation procedures
GB/T 15000.3, Directives for the work of reference materials -- Part 3: Reference materials -- Characterization and assessment of homogeneity and stability GB/T 16597, Analytical methods of metallurgical products -- General rule for X-ray fluorescence spectrometric methods
JJG 810, Verification Regulation for Wavelength Dispersive X-Ray Fluorescence Spectrometers
YB/T 082, Specification for certified reference materials for metallurgical product analysis
3 Terms and definitions
There are no terms or definitions to be defined in this document.
4 Principle
The sample and the cobalt internal standard added accurately in quantitative amounts are melted into a borate glass piece with the flux. Measure the X-ray fluorescence intensity of the element to be measured. Use the X-ray fluorescence intensity of the element to be measured (iron/cobalt X-ray fluorescence intensity ratio) to establish a calibration curve for the content of the element to be measured. Calculate the content of the element to be measured based on the calibration curve.
5 Reagents and materials
Unless otherwise stated, only approved analytically pure reagents and grade 3 or above distilled water complying with GB/T 6682 or water with equivalent purity are used in the analysis.
5.1 Iron dioxide (Fe2O3), guaranteed reagent. Burn ferric oxide at 1000??C for at least 1 h and cool to room temperature in a desiccator.
5.2 Copper oxide (CuO), guaranteed reagent. Burn copper oxide at 400??C for at least 1 h and cool to room temperature in a desiccator.
5.3 Zinc oxide (ZnO), guaranteed reagent. Burn zinc oxide at 400??C for at least 1 h and cool to room temperature in a desiccator.
5.4 Lead oxide (PbO), guaranteed reagent. Burn lead oxide at 400??C for at least 1 h and cool to room temperature in a desiccator.
5.5 Arsenic trioxide (As2O3), guaranteed reagent. Bake arsenic trioxide at 105??C for at least 1 h and cool to room temperature in a desiccator.
5.6 Chromium trioxide (Cr2O3), guaranteed reagent. Burn chromium trioxide at 400??C for at least 1 h and cool to room temperature in a desiccator.
5.7 Silica (SiO2), guaranteed reagent. Burn silica at 1000??C for at least 1 h and cool to room temperature in a desiccator.
5.8 Calcium carbonate (CaCO3), guaranteed reagent. Bake calcium carbonate at 105??C for at least 1 hour and cool to room temperature in a desiccator.
5.9 Magnesium oxide (MgO), guaranteed reagent. Burn magnesium oxide at 1000??C for at least 1 h and cool to room temperature in a desiccator. Weigh immediately. 5.10 Aluminum trioxide (Al2O3), guaranteed reagent. Ignite aluminum oxide at 1000??C for at least 2 h and cool to room temperature in a desiccator.
5.11 Manganese tetroxide (Mn3O4), guaranteed reagent. Bake manganese tetroxide at 105??C for at least 2 h and cool to room temperature in a desiccator.
5.12 Ammonium dihydrogen phosphate (NH4H2PO4), guaranteed reagent. Bake ammonium dihydrogen phosphate at 105??C for at least 1 h and cool to room temperature in a desiccator.
5.13 Potassium carbonate (K2CO3), guaranteed reagent. Bake potassium carbonate at 105??C for at least 1 h and cool to room temperature in a desiccator.
5.14 Titanium dioxide (TiO2), guaranteed reagent. Burn the titanium dioxide at 1000??C for at least 1 h and cool to room temperature in a desiccator.
5.15 Vanadium pentoxide (V2O5), guaranteed reagent. Bake vanadium pentoxide at 110??C for at least 1 h and cool to room temperature in a desiccator.
5.16 Ammonium sulfate [(NH4)2SO4], guaranteed reagent. Bake ammonium sulfate at 105??C for at least 1 h and cool to room temperature in a desiccator.
5.17 Lithium carbonate (Li2CO3), guaranteed reagent.
5.18 Cobalt trioxide (Co2O3). Bake cobalt oxide at 105??C for at least 1 h and cool to room temperature in a desiccator.
5.19 Anhydrous lithium tetraborate (Li2B4O7), guaranteed reagent.
7 Sampling and sample preparation
7.1 Laboratory specimens
Samples shall be taken and prepared in accordance with the provisions of GB/T 10322.1. The particle size of the specimen shall be less than 100 ??m. If the content of combined water or easy oxides in the specimen is high, the particle size shall be less than 160 ??m. For regulations regarding high combined water and easy oxide content, see GB/T 6730.1.
7.2 Preparation of pre-dried specimens
Prepare pre-dried specimens according to the provisions of GB/T 6730.1. 8 Preparation of glass pieces
8.1 General
When preparing glass pieces, the weighing amount of the test material is 0.4 g~0.8 g, accurate to 0.0001 g. The amount of flux used is 10 ~ 15 times the test material amount. The flux can be a single commercially available lithium tetraborate or a mixture of lithium tetraborate, lithium metaborate, and lithium carbonate [the ratio (mass fraction) of lithium metaborate to lithium tetraborate in the mixture is not greater than 0.3]. The weighed amount of cobalt trioxide is 0.1 g~0.2 g, accurate to 0.0001 g. The difference in the amount of cobalt trioxide in each glass piece shall not be greater than 0.2 mg. The melting temperature is 1040???~1100???.
Visually inspect the prepared glass pieces for defects such as unmelted material, crystallization, or bubbles. Defective glass pieces shall be discarded and prepared again. 8.2 Preparation of glass pieces for calibration
8.2.1 Preparation of synthetic calibration samples
Take the appropriate amount of the pure substance corresponding to the component being determined based on the conventional high-point content of the component being determined. After mixing the synthetic powder sample, grind it evenly. Transfer to a high temperature furnace at room temperature. Under the condition that the heating time is greater than 1 h, the temperature is raised to 950??C and kept for 20 min. Remove and place in a desiccator to cool to room temperature. Grind again to less than 0.2 mm. Well mix. Transfer to a high temperature furnace at 950??C again and keep for 20 min. Take out. After cooling slightly, transfer to a desiccator and cool to room temperature before use. Store unused samples in sealed containers. They can be reused within 4 h. 8.2.2 Preparation of glass pieces for serial calibration
The glass pieces used for series calibration shall be prepared with calibration samples prepared with high-purity reagents. However, certified reference materials/standard samples shall be used to verify their accuracy. Certified reference materials/samples with a certain concentration and gradient range can also be selected to prepare a series of glass pieces for calibration. It is also allowed to use a mixture of standard substances/samples or add high-purity reagents as calibration samples.
8.2.3 Preparation of glass pieces for synthetic calibration samples of pure substances
Calculate based on the molecular formula of the pure substance and the measured components. Weigh appropriate amounts of pure substances of determined composition and synthetic calibration samples in 8.2.1. Melt the glass piece for calibration. The preparation method of glass pieces for calibration shall be the same as the preparation method of glass pieces for measurement. You can choose any one of the methods 8.3, 8.4, 8.5, and 8.6 to complete.
When weighing reference materials or melted slices of high-purity reagents to prepare calibration curves, the direct weighing method can be used. Pay attention to the sensitivity of the balance when weighing. When the weighing amount is not more than 0.05 g, a balance with a weighing sensitivity higher than the analytical precision requirement shall be used for weighing (such as a balance with a graduation value of 0.02 mg), or a certified standard solution shall be used for quantitative addition. At this time, attention shall be paid to the medium of the standard solution.
8.2.4 Preparation of standard samples/standard substance glass pieces
The preparation method of glass pieces for calibration using standard samples/standard substances shall be consistent with the preparation method of glass pieces for sample measurement.
8.2.5 Preparation of standard samples/standard substances by adding pure substances to glass pieces
Weigh the weighing amount of standard sample/standard substance and pure substance calculated based on the molecular formula of the pure substance and the measured component. Melt the glass piece for calibration.
8.3 Pre-oxidize and then melt lithium tetraborate flux base
8.3.1 Weigh 1.00 g of lithium carbonate (see 5.17) (accurate to 0.01 g), 0.5000 g of test material (accurate to 0.0001 g) and 0.1000 g of cobalt trioxide (see 5.18) (accurate to 0.0001 g). Place in a 50 mL clean glass beaker. Mix well. Transfer to a crucible (see 6.5) that has been pre-added with 5.60 g of anhydrous lithium tetraborate (see 5.19) and standard and test material.
8.5.2 Move the crucible containing the mixed materials into a high temperature furnace of 450??? ??10??? (see 6.3). Raise the temperature to 600??? and hold for 10 min~20 min. Take out and transfer to 1050??? ??10??? melting furnace (see 6.4). After melting for 5 min~7 min, rock and melt for 15 min~18 min. Let stand for 1 min. Take out the crucible. Allow the melt in the crucible to cool naturally to room temperature. Weigh the total mass of the crucible and the melt in it, recorded as m2 (accurate to 0.0001 g). The glass piece shall be obtained by demolding.
8.6 Pre-oxidize and then melt in a cobalt-containing internal standard flux crucible - add boric acid
8.6.1 Weigh 1.00 g of lithium carbonate (see 5.17) (accurate to 0.01 g) and 0.5000 g of test material (accurate to 0.0001 g). Place in a 50 mL clean glass beaker. Mix well. Transfer to a crucible containing internal standard flux (see 5.21). Add 0.15 mL~0.25 mL of ammonium bromide solution (see 5.22) [Note that Br interferes with Al and shall be calibrated, or add 0.2 mL~1.0 mL of ammonium iodide solution (see 5.23)] to the mixture of lithium carbonate and test material.
8.6.2 Transfer the internal standard flux crucible (see 5.21) and its contents to a clean ceramic crucible cover. And move it into a high temperature furnace of 450?????10??? (see 6.3). Raise the temperature to 500??C and keep it for 20 min. Then the temperature is raised to 600??C and kept for 20 min. Finally, the temperature is raised to 650??C and maintained for 20 min. Take it out after completing pre-oxidation.
Transfer the pre-oxidized materials and the internal standard flux crucible (see 5.21) to a crucible with a mass of m1 (accurate to 0.0001 g) filled with 3.01 g of anhydrous boric acid (see 5.20) after constant weight. (see 6.5). Then transfer the crucible together with the contents to a 1050??C ??10??C melting furnace (see 6.4). After melting for 5 min~7 min, rock and melt for 15 min~18 min. Let stand for 1 min. Take out the crucible. Allow the melt in the crucible to cool naturally to room temperature. Weigh the total mass of the crucible and the melt in it, recorded as m2 (accurate to 0.0001 g). The glass piece shall be obtained by demolding.
When preparing glass pieces, note the followings:
- The melting conditions of the high-temperature melting furnace are not limited to the specified melting temperature and time. Other melting temperatures and melting times may be selected to prepare glass pieces. The weighing sample size is not limited to 0.5000 g. The amount of cobalt trioxide added is not limited to 0.1000 g. There is no limit on the amount of flux. Other weighing volumes and flux dosages can be selected. At the same time, ensure that the melted glass pieces are uniform and intact and use the correct calculation formula;
- When casting with a secondary mold, both the melting crucible and the mold shall be weighed;
- When using ammonium iodide as a release agent, the ammonium iodide solution shall be added to the mixture of lithium carbonate and the test material. Iodide release agents Pb, As, S may sometimes be lost. If ammonium iodide release agent is required, it shall be added after pre-oxidation is completed;
- When using the AsK?? line, Pb interferes shall be corrected.
9 Instrument preparation
9.1 Instrument working environment
The working environment of the instrument shall meet the requirements of GB/T 16597. 9.2 Instrument working conditions
The working conditions of the X-ray spectrometer shall be optimized according to the instrument manufacturer's requirements before measurement. Use until the instrument is stable.
10 Analysis steps
10.1 Number of measurements
According to the requirements of Annex B, the same pre-dried specimen shall be measured independently at least twice.
NOTE: "Independently" means that the results of the second and subsequent measurements are not affected by the results of the previous measurements. In this analytical method, this condition means that in the same laboratory, by the same operator, using the same equipment, according to the same test method, repeated measurements are independently made on the same measured object in a short period of time, including the use of appropriate recalibration.
10.2 Measurement conditions
Before starting the measurement, confirm the following measurement conditions: a) Select appropriate measurement conditions based on the type of instrument used, analytical elements, coexisting elements, and content variation ranges; b) The counting time for analyzing elements depends on the content of the element being measured and the analytical precision achieved, and is generally 5 s~60 s; c) The counting rate does not exceed the maximum linear counting rate of the counter used;
d) The selection of light tube voltage and current shall consider the minimum

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