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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 6900-2006 Chemical analysis of alumina-silica refractories. The following technical changes have been made with respect to GB/T 6900-2006:
——determination ranges of zirconium oxide and chromic oxide items are added (see Clause 1);
——determination for elements such as residual silicon dioxide, iron oxide, calcium oxide, magnesium oxide, potassium oxide, sodium oxide, phosphorus pentoxide, zirconium oxide and chromic oxide is added; the determination range of phosphorus pentoxide and manganese oxide by inductively coupled plasma-atomic emission spectroscopy is extended (see Clause 17);
——the allowable deviation of analysis value is modified (see Clause 6);
——method for determining the potassium oxide and sodium oxide by flame photometer is added (see 14.2);
——establishment of standard curve for inductively coupled plasma-atomic emission spectrograph is added (see Annex B).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by and is under the jurisdiction of the National Technical Committee on Refractory Material of Standardization Administration of China (SAC/TC 193).
The previous editions of this standard are as follows:
——GB/T 6900-1986, GB/T 6900-2006.
Chemical analysis of alumina-silica refractories
1 Scope
This standard specifies the chemical analysis of alumina-silica refractories.
This standard is applicable to the determination of loss on ignition and the content of silicon dioxide, aluminum oxide, iron oxide, titanium dioxide, calcium oxide, magnesium oxide, potassium oxide, sodium oxide, manganese oxide, phosphorus pentoxide, zirconium oxide and chromic oxide in alumina-silica refractories. See Table 1 for the determination range.
Table 1 Determination range
Analytical item Content range/% Analytical item Content range/%
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 4984 Chemical analysis of refractories containing zirconia
GB/T 7728 Chemical analysis of metallurgical products - General rule for flame atomic absorption spectrometric methods
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10325 Shaped refractory products - Rule of acceptance, sampling and inspection
GB/T 12805 Laboratory glassware - Burettes
GB/T 12806 Laboratory glassware - One-mark volumetric flask
GB/T 12808 Laboratory glassware - One-mark pipettes
GB/T 17617 Refractory products - Sampling of raw materials and unshaped products
GB/T 32179 Chemical analysis of refractories - General requirements for wet chemical analysis, atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) methods
3 Instruments and apparatus
3.1 Balance (with a sensibility of 0.1mg).
3.2 Platinum crucible or porcelain crucible (30mL).
3.3 Automatic temperature-controlled dryer.
3.4 High temperature furnace: electric box furnace with maximum service temperature ≥1100℃ and capable of controlling temperature automatically.
3.5 Spectrophotometer.
3.6 Flame photometer.
3.7 Inductively coupled plasma-atomic emission spectrometer.
3.8 Pipette: Class A in GB/T 12808.
3.9 Burette: Class A in GB/T 12805.
3.10 Volumetric flask: Class A in GB/T 12806.
3.11 Atomic absorption spectrometer: equipped with air-acetylene burner and calcium, magnesium, potassium, sodium and manganese hollow cathode lamps. Air and acetylene gas shall be pure enough (free from water, oil, calcium, magnesium, potassium, sodium and manganese) to provide stable and clear fuel-lean flame. The "minimum requirements for accuracy", "characteristic concentration", "detection limit" and "linearity (degree of bending) of the standard curve" shall be in accordance with GB/T 7728.
4 Test sample preparation
4.1 Sampling
Laboratory samples of shaped refractories are taken according to GB/T 10325 while those of unshaped refractories according to GB/T 17617.
4.2 Preparation
4.2.1 The laboratory sample is crushed to particles less than 6.7mm and cut down to about 100g by quartering method.
4.2.2 An exception may be made when sampling provisions are otherwise specified in the contract or a laboratory sample ≥100g is not available due to product form restrictions.
4.2.3 The sample after reduction is crushed to particles less than 0.5mm, then reduced again, and processed into test sample with particle size less than 0.090mm.
4.2.4 Before being analyzed, the test sample shall be dried at 105~110℃ for 2h, and then cooled to room temperature in dryer.
5 General rules
5.1 Determination times
Carry out determination twice under repeatability conditions.
5.2 Blank test
Carry out blank test under repeatability conditions.
5.3 Expression of result
All results shall be rounded off in accordance with GB/T 8170. Where the content is not less than 0.10%, 2 decimal places are reserved in the result; where the content is less than 0.10%, two significant digits are reserved in the result; if specific requirements are given in the client’s supply contract or relevant standard, the results may be rounded off to the required digits.
5.4 Adoption of analysis result
Where the difference between the two effective analysis values of the test sample obtained is not greater than the allowable deviation specified in Table 2, the arithmetic mean is used as the final analysis result; otherwise, additional analysis and data processing shall be performed as specified in Annex A.
5.5 Quality assurance and control
5.5.1 The standard curve shall be calibrated once with standard substances regularly (not exceeding 3 months). If the instrument is repaired or its components (such as a light bulb) are replaced, the standard curve shall be replotted and calibrated with the same type of standard substance. Where the difference between the analysis value of the standard substance and the standard value is greater than 0.7 times of the allowable deviation specified in Table 2, the standard curve shall be replotted.
5.5.2 Under normal circumstances, the concentration of the standard titration solution shall be recalibrated once every 2 months; if the temperature change within 2 months exceeds 10℃ , the solution shall be recalibrated timely. After recalibration, it shall be verified with standard substance. Where the difference between the analysis value of the standard substance and the standard value is not greater than 0.7 times of the allowable deviation specified in Table 2, the calibration result is valid; otherwise invalid.
In the arbitration test, the same type of standard substance shall be analyzed together with the test sample. Where the difference between the analysis value of the standard substance and the standard value is not greater than 0.7 times of the allowable deviation specified in Table 2, the analysis value of test sample is valid; otherwise invalid.
Foreword i
1 Scope
2 Normative references
3 Instruments and apparatus
4 Test sample preparation
5 General rules
6 Test report
7 Determination of loss on ignition
8 Determination of silicon dioxide
9 Determination of aluminum oxide
10 Determination of iron oxide
11 Determination of titanium dioxide
12 Determination of calcium oxide
13 Determination of magnesium oxide
14 Determination of potassium oxide and sodium oxide
15 Determination of manganese oxide - flame atomic absorption spectrometric method [0.01%≤ω(MnO)≤0.25%]
16 Determination of phosphorus pentoxide [molybdenum blue spectrophotometric method 0.05%≤ω(P2O5)≤5%]
17 Determination of silicon dioxide, iron oxide, titanium dioxide, calcium oxide, magnesium oxide, potassium oxide, sodium oxide, manganese oxide, phosphorus pentoxide, zirconium oxide and chromic oxide [inductively coupled plasma-atomic emission spectroscopy ω(MxOy)≤15%]
Annex A (Normative) Acceptance procedures for analysis value
Annex B (Informative) Establishment of standard curve for inductively coupled plasma-atomic emission spectrograph
