GB/T 6900: Evolution and historical versions
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| GB/T 6900-2025 | English | RFQ |
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Chemical analysis of alumino - silicate refractories
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GB/T 6900-2025
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| GB/T 6900-2016 | English | 395 |
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Chemical analysis of alumina-silica refractories
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| GB/T 6900-2006 | English | RFQ |
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Chemical analysis of alumina-silica refractories
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GB/T 6900-2006
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| GB/T 6900.1-1986 | English | 199 |
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Fireclay and high-alumina refractories--Determination of loss content on ignition--Gravimetric method
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GB/T 6900.1-1986
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Basic data | Standard ID | GB/T 6900-2025 (GB/T6900-2025) | | Description (Translated English) | Chemical analysis of alumino - silicate refractories | | Sector / Industry | National Standard (Recommended) | | Date of Implementation | 2026-03-01 | | Older Standard (superseded by this standard) | GB/T 6900-2016 | GB/T 6900-2016: Chemical analysis of alumina-silica refractories---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Chemical analysis of alumina-silica refractories
ICS 81.080
Q40
National Standards of People's Republic of China
Replace GB/T 6900-2006
Aluminum silicon refractory chemical analysis method
Released on.2016-08-29
2017-07-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration issued
Content
Foreword I
1 Scope 1
2 Normative references 1
3 Instruments and equipment 1
4 sample preparation 2
5 General 2
6 Test report 3
7 Determination of ignition loss 3
8 Determination of silica 3
9 Determination of alumina 8
10 Determination of iron oxide 14
11 Determination of titanium dioxide 15
12 Determination of calcium oxide 18
13 Determination of magnesium oxide 22
14 Determination of potassium oxide and sodium oxide 23
15 Determination of manganese oxide [Flame atomic absorption spectrometry [0.01% ≤ w (MnO) ≤ 0.25%]] 28
16 Determination of phosphorus pentoxide [molybdenum blue spectrophotometry 0.05% ≤ w (P2O5) ≤ 5%] 29
17 silica, iron oxide, titanium dioxide, calcium oxide, magnesium oxide, potassium oxide, sodium oxide, manganese monoxide, phosphorus pentoxide, zirconium oxide,
Determination of chromium oxide [Inductively coupled plasma emission spectrometry w (MxOy) ≤ 15%] 31
Appendix A (Normative) Analytical Value Acceptance Procedures 34
Appendix B (informative) The establishment of a standard curve for inductively coupled plasma emission spectrometers 35
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 6900-2006 "Aluminum-silicon refractory chemical analysis method". Compared with GB/T 6900-2006, mainly
The technical content changes as follows.
--- Increased the measurement range of zirconia and chromic oxide projects (see Chapter 1);
--- Increased inductively coupled plasma emission spectrometry for the determination of residual silica, iron oxide, calcium oxide, magnesium oxide, potassium oxide, oxidation
Elements such as sodium, phosphorus pentoxide, zirconium oxide and chromium oxide have been expanded by inductively coupled plasma emission spectrometry for the determination of pentoxide
The range of phosphorus and manganese monoxide (see Chapter 17);
--- Modified the analysis value tolerance (see Chapter 6);
--- Increased the method of measuring potassium oxide and sodium oxide by flame photometer (see 14.2);
--- Increased the establishment of a standard curve for inductively coupled plasma emission spectrometers (see Appendix B).
Please note that some of the contents of this document may involve patents. The issuing organization of this document is not responsible for identifying these patents.
This standard is proposed and managed by the National Technical Committee for Refractory Standardization (SAC/TC193).
This standard was drafted. Sinosteel Luoyang Refractory Materials Research Institute Co., Ltd., Zhejiang Mingde New Material Technology Co., Ltd., Tongda Nai
Fire Technology Co., Ltd., Beijing Pufang General Instrument Co., Ltd., Zhejiang Hongying Group Co., Ltd., Jiangsu Yuezhan New Materials
Materials Co., Ltd.
The main drafters of this standard. Cao Haijie, Yan Chang, Yan Peizhong, Liang Xianlei, Luo Huaming, Yan Bingquan, Xu Xiaoying, Ye Xiaoxing, Wang Benhui,
Zheng Qinglin, Liu Jinghui, Li Zuonian, Cai Haolin, Zhang Liyan, Zhang Zhouming.
The previous versions of the standards replaced by this standard are.
---GB/T 6900-1986, GB/T 6900-2006.
Aluminum silicon refractory chemical analysis method
1 Scope
This standard specifies the chemical analysis method for aluminum-silicon refractories.
This standard applies to aluminum-silicon refractories burning reduction, silica, alumina, iron oxide, titanium dioxide, calcium oxide, magnesium oxide,
Determination of the content of potassium oxide, sodium oxide, manganese monoxide, phosphorus pentoxide, zirconium oxide, and chromium oxide. The measurement range is shown in Table 1.
Table 1 Measurement range
Analysis item content range /% Analysis item content range /%
LOI ≤30 K2O ≤4
SiO2 ≤95 Na2O ≤8
Al2O3 10~97 MnO ≤5
Fe2O3 ≤15 P2O5 ≤10
TiO2 ≤10 ZrO2 ≤5
CaO ≤20 Cr2O3 ≤3
MgO ≤ 2
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 4984 Zirconium refractory chemical analysis method
GB/T 7728 Metallurgical products - Chemical analysis - General rules for flame atomic absorption spectrometry
GB/T 8170 Numerical Rounding Rules and Representation and Determination of Limit Values
GB/T 10325 Shaped Refractory Products Acceptance Sampling Inspection Rules
GB/T 12805 laboratory glass instrument burette
GB/T 12806 laboratory glass instrument single standard line volumetric flask
GB/T 12808 laboratory glass instrument single standard line pipette
GB/T 17617 Sampling of refractory raw materials and unshaped refractory materials
GB/T 32179 Refractory chemical analysis Wet method, atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission
General requirements for spectroscopy (ICP-AES)
3 Instruments and equipment
3.1 Balance (sensing 0.1mg).
3.2 Platinum crucible or porcelain crucible (30 mL).
3.3 Automatic temperature control drying oven.
3.4 High temperature furnace. The box type electric furnace with the highest operating temperature ≥1100 °C and automatic temperature control.
3.5 Spectrophotometer.
3.6 Flame photometer.
3.7 Inductively coupled plasma emission spectrometer.
3.8 Pipette. GB/T 12808A.
3.9 Burette. GB/T 12805A grade.
3.10 Volumetric flask. GB/T 12806A.
3.11 Atomic Absorption Spectrometer. equipped with air-acetylene burner, calcium, magnesium, potassium, sodium and manganese hollow cathode lamps. Air and acetylene gas should be sufficient
Pure (no water, oil, calcium, magnesium, potassium, sodium, manganese) to provide a stable and clear lean flame. Its "minimum requirement for precision" "characteristic concentration"
The “detection limit” and “linearity of the standard curve (degree of bending)” shall comply with the provisions of GB/T 7728.
4 sample preparation
4.1 Sampling
Shaped refractory materials According to GB/T 10325, amorphous and refractory raw materials are collected in accordance with GB/T 17617.
4.2 Preparation
4.2.1 The laboratory sample is broken to below 6.7 mm and reduced to about 100 g by quartering.
4.2.2 An exception may be made when the contract is otherwise sampled or due to product form limitations, laboratory samples of ≥100g are not available.
4.2.3 The sample after the shrinkage is pulverized to less than 0.5 mm, the shrinkage is continued, and the sample is processed into a sample having a particle size of less than 0.090 mm.
4.2.4 Before the sample is analyzed, it should be baked at 105 ° C ~ 110 ° C for 2 h, placed in a desiccator and cooled to room temperature.
5 General
5.1 Number of measurements
It was measured twice under repetitive conditions.
5.2 Blank test
A blank test was performed under repetitive conditions.
5.3 Expression of results
The results should be revised according to GB/T 8170. Two decimal places are retained when the content is ≥0.10%; two results are retained when the content is < 0.10%
A valid number; if the client's supply contract or related standards require otherwise, the number of digits can be revised.
5.4 Adoption of analytical results
When the difference between the two valid analytical values of the obtained sample is not greater than the allowable difference specified in Table 2, the arithmetic mean is used as the final analysis.
Results; otherwise, additional analysis and data processing should be performed as specified in Appendix A.
5.5 Quality Assurance and Control
5.5.1 The standard curve shall be calibrated once with the reference material on a regular basis (not more than 3 months). If the instrument is repaired or replaced (such as a light bulb, etc.)
The standard curve should be redrawn and calibrated with the same type of standard material. When the difference between the analytical value of the reference material and the standard value is greater than that specified in Table 2
When the tolerance is 0.7 times, the standard curve should be redrawn.
5.5.2 In general, the concentration of the standard titration solution should be recalibrated every 2 months; if the temperature changes over 10 °C within 2 months
When it is time, it should be calibrated once. After recalibration, the standard substance is used for verification. When the difference between the analytical value of the standard substance and the standard value is not more than
When the allowable difference is 0.7 times as specified in Table 2, the calibration result is valid, otherwise it is invalid.
In the arbitration test, the same type of reference material should be analyzed along with the sample. When the difference between the analytical value of the reference material and the standard value is not greater than that in Table 2
When the allowable difference is 0.7 times, the sample analysis value is valid, otherwise it is invalid.
6 test report
The test report should include at least the following.
---Requester;
--- Sample name;
--- Analysis results;
--- Differences with the prescribed analysis steps (if necessary);
--- Anomalies observed in the test (if necessary);
--- Test date.
Table 2 Allowable difference of analytical values
Content range /%
Allowable difference for each element /%
LOI SiO2 Al2O3 Fe2O3 TiO2 CaO MgO K2O Na2O P2O5 MnO, ZrO2, Cr2O3
≤0.1
>0.1~≤0.5
>0.5~≤1
>1~≤2
>2~≤5
>5~≤15
>15~≤30
0.05
0.10
0.20
0.30
0.05
0.10
0.20
0.30
0.40
0.50
0.03
0.10
0.20
0.30
0.01
0.02
0.10
0.20
0.30
0.02
0.05
0.10
0.15
0.20
0.30
0.02
0.05
0.10
0.15
0.02
0.06
0.10
0.20
0.30
0.02
0.06
0.10
0.20
0.30
0.02
0.04
0.10
0.15
0.20
0.30
0.01
0.02
0.05
0.10
0.20
>30~≤60 - 0.50 0.60 - - - - - - -
>60 - 0.60 0.70 - - - - - - -
For the trace component, when the average value of the analysis value is less than 2 times the allowable difference, the allowable difference is 1/2 of the analysis value.
7 Determination of ignition loss
The measurement was carried out in accordance with the ignition reduction method in GB/T 32179.
8 Determination of silica
8.1 Molybdenum blue light method [w(SiO2)≤5%]
8.1.1 Principle
The sample was melted with a sodium carbonate-boric acid mixed flux and dilute with hydrochloric acid. Monosilicic acid and ammonium molybdate in about 0.2 mol/L hydrochloric acid medium
The silicon-molybdenum heteropoly acid is added with oxalic acid-sulfuric acid mixed acid to eliminate the interference of phosphorus and arsenic, and then reduced to silicon molybdenum blue with ammonium ferrous sulfate.
The absorbance of the photometer was measured at a wavelength of 810 nm or 690 nm.
8.1.2 Reagents
8.1.2.1 Mixed flux. Take 2 parts of anhydrous sodium carbonate and 1 part of boric acid, and mix.
8.1.2.2 Hydrochloric acid (1 5).
8.1.2.3 Ammonium molybdate [(NH4)6MO7O24·4H2O] solution (50g/L). used after filtration.
8.1.2.4 Mixed acid of oxalic acid-sulfuric acid. 15 g of oxalic acid (H2C2O4·2H2O) is dissolved in 250 mL of sulfuric acid (18) and diluted with water.
Mix to 1000 mL.
8.1.2.5 Ammonium ferrous sulfate [FeSO4·(NH4)2SO4·6H2O] solution (40g/L). Take 4g of ammonium ferrous sulfate dissolved in water, add 5mL
Sulfuric acid (1 1), diluted to 100 mL with water, mixed, filtered and used, prepared at the time of use.
8.1.2.6 Standard storage solution of silica (containing SiO20.5mg/mL).
Weigh 0.1000g of silica (99.99%) previously calcined at 1000 °C for 2h and cooled to room temperature in platinum crucible, add 2g~
3 g of anhydrous sodium carbonate, covered with a lid and slightly left a gap, placed in a high temperature furnace at 1000 ° C for 5 min ~ 10 min, taken out and cooled. Placed
In a Teflon beaker containing 100 mL of boiling water, immerse the frit at low temperature until the solution is clear, wash the crucible and cover with hot water, and cool to the chamber.
temperature. Transfer to a.200 mL volumetric flask, dilute to the mark with water, shake well, and store in a plastic bottle.
8.1.2.7 Silica standard solution (containing SiO250μg/mL). Pipette 10.00mL of silica standard storage solution (8.1.2.6)
In a 100 mL volumetric flask, dilute to the mark with water, shake well, and prepare when used.
8.1.2.8 Silica standard solution (containing SiO25μg/mL). Pipette 10.00mL of silica standard solution (8.1.2.7) in 100mL
In a volumetric flask, dilute to the mark with water, shake well, and prepare when used.
8.1.3 Sample quantity
Approximately 0.10 g of the sample was weighed to the nearest 0.1 mg.
8.1.4 Determination
8.1.4.1 Place the sample in a platinum crucible containing 4 g of mixed flux (8.1.2.1), mix well, cover 1 g of mixed flux, cover with a lid and
Leave a gap, place it in a high temperature furnace at 800 ° C ~ 900 ° C, and heat up to 1000 ° C ~ 1100 ° C melting, until the sample is completely melted. Take out
Turn the crucible so that the melt adheres evenly to the inner wall of the crucible and cools.
8.1.4.2 Wipe the outer wall of the crucible with filter paper and place it in a.200 mL beaker containing 60 mL of hydrochloric acid (8.1.2.2).
After the solution is clear, wash the lid and lid with water, cool to room temperature, transfer to a 100 mL volumetric flask, dilute to the mark with water, and shake.
8.1.4.3 Pipette 10.00 mL of test solution (8.1.4.2) into a 100 mL volumetric flask and add 10 mL of water.
8.1.4.4 Add 5mL ammonium molybdate solution (8.1.2.3), shake well, and let stand at room temperature for 20min (room temperature below 15 °C is about 30 °C)
In a warm water bath).
8.1.4.5 Add 30mL of oxalic acid-sulfuric acid mixed acid (8.1.2.4), shake well, place for 0.5min~2min, add 5mL ammonium ferrous sulfate
Solution (8.1.2.5), dilute to the mark with water and shake well.
8.1.4.6 Using a suitable absorption dish (see Table 3), measure the absorption with a blank test solution at a spectrophotometer of 810 nm or 690 nm.
Luminosity.
Table 3 Select the absorption dish according to the content of silica
w(SiO2)/% 0.1~0.5 0.5~5
Absorbing dish/mm 30 10
Standard curve 8.1.5.1 8.1.5.2
8.1.5 Drawing of standard curve
8.1.5.1 Pipette 0mL, 1.00mL, 2.00mL, 4.00mL, 6.00mL, 8.00mL, 10.00mL silica standard with burette
The solution (8.1.2.8) was placed in a set of 100 mL volumetric flasks, 2.5 mL of hydrochloric acid (8.1.2.2) was added, and water was added to 20 mL. The following is 8.1.4.4~
8.1.4.5 operation, using a 30mm absorption dish, at the wavelength of 810nm of the spectrophotometer, measuring the absorbance with the reagent blank as a reference, drawing the standard
Quasi-curve.
8.1.5.2 Pipette 0mL, 1.00mL, 2.00mL, 4.00mL, 6.00mL, 8.00mL, 10.00mL silica standard with burette
The solution (8.1.2.7) was placed in a set of 100 mL volumetric flasks, 2.5 mL of hydrochloric acid (8.1.2.2) was added, and water was added to 20 mL. The following is 8.1.4.4~
8.1.4.5 operation, using a 10mm absorption dish, at the wavelength of 690nm of the spectrophotometer, measuring the absorbance with the reagent blank as a reference, drawing
standard curve line.
8.1.6 Calculation of analysis results
The amount of silica is calculated by mass fraction w (SiO2), and the value is expressed in %, calculated according to formula (1).
w(SiO2)=
M1
mV1/V×
100 (1)
In the formula.
M1---the value of the amount of silica found from the standard curve, in grams (g);
V1---The value of the volume of the test solution, in milliliters (mL);
V --- the total volume of the test solution, in milliliters (mL);
m --- The value of the mass of the sample in grams (g).
8.2 Depolymerization of molybdenum blue light method [5% ≤ w (SiO2) ≤ 15%]
8.2.1 Principle
The sample was melted with a sodium carbonate-boric acid mixed flux and dilute with hydrochloric acid. Adding an excessive amount of potassium fluoride to produce a highly polymerized silicic acid
SiF62-, an excess of F-added boric acid complex, in a medium of about 0.2mol/L hydrochloric acid, monosilicic acid and ammonium molybdate form a silicon molybdenum heteropoly acid, added
The oxalic acid-sulfuric acid mixed acid eliminates the interference of phosphorus and arsenic, and then reduces it to silicon molybdenum blue with ammonium ferrous sulfate at the wavelength of the spectrophotometer.
At 690 nm, the absorbance was measured.
8.2.2 Reagents
8.2.2.1 Mixing flux. Take 2 parts of anhydrous sodium carbonate and 1 part of boric acid, and mix.
8.2.2.2 Potassium fluoride (20g/L). stored in plastic bottles.
8.2.2.3 Hydrochloric acid (1 5).
8.2.2.4 Hydrochloric acid (1 1).
8.2.2.5 Boric acid (20g/L).
8.2.2.6 Ammonium molybdate [(NH4)6MO7O24·4H2O] solution (50g/L). used after filtration.
8.2.2.7 Mixed acid of oxalic acid-sulfuric acid. 15 g of oxalic acid (H2C2O4·2H2O) is dissolved in 250 mL of sulfuric acid (18) and diluted with water.
Mix to 1000 mL.
8.2.2.8 Ammonium ferrous sulfate [FeSO4·(NH4)2SO4·6H2O] solution (40g/L). Take 4g of ammonium ferrous sulfate dissolved in water, add 5mL
Sulfuric acid (1 1), diluted to 100 mL with water, mixed, filtered and used, prepared at the time of use.
8.2.2.9 Sodium hydroxide solution (200g/L). Store in plastic bottles.
8.2.2.10 p-Nitrophenol solution (5 g/L). Prepared with ethanol.
8.2.2.11 Silica standard solution (containing SiO20.1mg/mL).
Weigh 0.1000g of silica (99.99%) previously calcined at 1000 °C for 2h and cooled to room temperature in platinum crucible, add 2g~
3 g of anhydrous sodium carbonate, covered with a lid and slightly left a gap, placed in a high temperature furnace at 1000 ° C for 5 min ~ 10 min, taken out and cooled. Placed
In a Teflon beaker containing 100 mL of boiling water, immerse the frit at low temperature until the solution is clear, wash the crucible and cover with hot water, and cool to the chamber.
temperature. Transfer to a 1000 mL volumetric flask, dilute to the mark with water, shake well, and store in a plastic bottle.
8.2.3 Sample volume
Approximately 0.10 g of the sample was weighed to the nearest 0.1 mg.
8.2.4 Determination
8.2.4.1 Place the sample in a platinum crucible containing 4 g of mixed flux (8.2.2.1), mix well, cover 1 g of mixed flux, cover with a lid and
Leave a gap, place it in a high temperature furnace at 800 ° C ~ 900 ° C, and heat up to 1000 ° C ~ 1100 ° C melting, until the sample is completely melted. Take out
Turn the crucible so that the melt adheres evenly to the inner wall of the crucible and cools.
8.2.4.2 Wipe the outer wall with filter paper and place in a.200 mL beaker containing 20 mL of hydrochloric acid (8.2.2.4) and 20 mL of water.
Leach the melt until the solution is clear, wash the lid and lid with water, cool to room temperature, transfer to a.200 mL volumetric flask, and dilute to the mark with water.
Shake well.
8.2.4.3 Pipette 10.00 mL of test solution (8.2.4.2) into a 100 mL plastic beaker using a pipette.
8.2.4.4 Add 5 mL of potassium fluoride solution (8.2.2.2) in a plastic measuring cup, shake well, and let stand for 10 min. Then add 7.5mL boric acid solution
(8.2.2.5), add 1 drop of p-nitrophenol solution (8.2.2.10), adjust to a yellow color with sodium hydroxide solution (8.2.2.9), then add 2.5mL
Hydrochloric acid (8.2.2.3).
8.2.4.5 Add 5mL ammonium molybdate solution (8.2.2.6), shake well, and leave it at room temperature for 20min (room temperature below 15 °C is about 30 °C)
In a warm water bath).
8.2.4.6 Add 30mL of oxalic acid-sulfuric acid mixed acid (8.2.2.7), shake well, place for 0.5min~2min, add 5mL ammonium ferrous sulfate
Solution (8.2.2.8), transfer the solution to a 100 mL volumetric flask, dilute to the mark with water, and shake well.
8.2.4.7 Using a 5 mm absorption dish, measure the absorbance at 690 nm of the spectrophotometer with a blank test solution as a reference.
8.2.5 Drawing of standard curve
Pipette 0 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, 10.00 mL of silica standard solution with a burette
(8.2.2.11) respectively placed in a set of 100mL plastic beakers, the following operations according to 8.2.4.4 ~ 8.2.4.6, with 5mm absorption dish, in the split light
The absorbance was measured at 690 nm with a reagent blank as a reference, and a standard curve was drawn.
8.2.6 Calculation of analysis results
The amount of silica is calculated by mass fraction w (SiO2), and the value is expressed in %, calculated according to formula (2).
w(SiO2)=
M1
mV1/V×
100 (2)
In the formula.
M1---the value of the amount of silica found from the standard curve, in grams (g);
V1---The value of the volume of the test solution, in milliliters (mL);
V --- the total volume of the test solution, in milliliters (mL);
m --- The value of the mass of the sample in grams (g).
8.3 Cohesive weight method [5% ≤ w (SiO2) ≤ 95%]
8.3.1 Principle
The sample is melted with a sodium carbonate-boric acid mixed flux, leached with hydrochloric acid, evaporated to a wet salt state, and condensed with silicic acid using polyoxyethylene as a coagulant.
Filter and burn to silica. It is then treated with hydrofluoric acid to remove the silicon in the form of silicon tetrafluoride. The difference in mass before and after hydrofluoric acid treatment
It is the main amount of silica. The residue is treated with a flux, dilute with hydrochloric acid, and the filtrate is combined to form a molybdenum blue light method or an inductively coupled plasma.
The amount of residual silica in the solution was determined by spectroscopy, and the sum of the two was the amount of silica in the sample.
8.3.2 Reagents
8.3.2.1 Anhydrous sodium carbonate.
8.3.2.2 Mixed flux. Take 2 parts of anhydrous sodium carbonate and 1 part of boric acid, and mix.
8.3.2.3 Ammonium molybdate [(NH4)6MO7O24·4H2O] solution (50g/L). used after filtration.
8.3.2.4 Ammonium ferrous sulfate solution (40g/L). Take 4g of ammonium ferrous sulfate [FeSO4 · (NH4) 2SO4 · 6H2O] dissolved in water, plus
5mL sulfuric acid (1 1), diluted with water to 100mL, mixed, filtered and used, prepared when used.
8.3.2.5 Mixed solution of oxalic acid-sulfuric acid. 15 g of oxalic acid (H2C2O4·2H2O) is dissolved in 250 mL of sulfuric acid (18), diluted with water
Release to 1000mL, mix and filter.
8.3.2.6 Polyethylene oxide solution (2.0g/L). Dissolve 0.4g of polyethylene oxide into.200mL of water. Guaranteed to use for two weeks.
8.3.2.7 Silver nitrate solution (10g/L).
8.3.2.8 Hydrofluoric acid (40%).
8.3.2.9 Hydrochloric acid (ρ=1.19g/mL).
8.3.2.10 Hydrochloric acid (1 1).
8.3.2.11 Sulfuric acid (1 1).
8.3.2.12 Silica standard solution (containing SiO20.5mg/mL). same as 8.1.2.6.
8.3.2.13 Silica standard solution (containing SiO20.005mg/mL). Pipette 10.00mL silica standard solution with pipette
(8.3.2.12) In a 1000 mL volumetric flask, dilute to the mark with water and shake well.
8.3.3 Sample volume
Approximately 0.50 g of the sample was weighed to the nearest 0.1 mg.
8.3.4 Determination
8.3.4.1 Place the sample in a platinum crucible containing 4 g of mixed flux (8.3.2.2) and mix. Another 1g mixed flux (8.3.2.2) is used to cover it.
On the top, the cover is placed in a high temperature furnace at about 800 ° C, and the temperature is raised to 1000 ° C ~ 1100 ° C for 15 min ~ 20 min, until the sample is completely melted. take
When it is rotated, the crucible is rotated so that the melt adheres uniformly to the inner wall of the crucible and is cooled.
8.3.4.2 Place the crucible and lid in a beaker containing 50 mL of hydrochloric acid (8.3.2.10) and heat on the electric furnace until the melt is completely dissolved.
Wash the lid and lid with water.
8.3.4.3 Place the beaker on a boiling water bath, dip it to a wet salt and remove it. Cool to room temperature and wipe the glass rod and the side wall of the beaker with filter paper.
Put in a beaker.
8.3.4.4 Add 3mL polyoxyethylene solution (8.3.2.6), stir well, mash the cake with glass rod, place for 5min, then add 70 °C~
The salt is completely dissolved in hot water at 80 ° C from 50 mL to 70 mL, filtered through a long neck funnel and medium speed quantitative filter paper, and the filtrate is used in a 250 mL volumetric flask.
Undertake. Transfer the pellet to the filter paper and wash it with hot water until it is free of chloride ions (check with silver nitrate).
8.3.4.5 Place the precipitate together with the filter paper in a platinum crucible, place it in a muffle furnace below 700 °C, open the furnace door and ash at low ...
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