Some standard content:
Light Industry Standard of the People's Republic of China
Chemical Analysis Method of Gypsum for Ceramic
1 Subject Content and Scope of Application
QB/T1641--1992
This standard specifies the analysis methods of gypsum adsorbed water, crystal water, acid insoluble matter, sulfur trioxide, calcium oxide, magnesium oxide, silicon dioxide, aluminum trioxide, iron trioxide, titanium dioxide, potassium oxide, and sodium oxide. This standard is applicable to the quantitative chemical analysis of natural gypsum containing calcium sulfate dihydrate as the main component and gypsum powder for ceramic molds containing calcium sulfate hemihydrate as the main component.
2 General
2.1 The water used for analysis is distilled water or deionized water of corresponding purity. 2.2 Unless otherwise specified, analytical reagents are used as analytical reagents; standard solutions are calibrated with reference reagents; and all solutions used refer to aqueous solutions.
Analytical instruments and volumetric instruments must be regularly calibrated and qualified by the statutory metrology and verification departments. 2.4
The constant weight during the analysis process is that the difference between the weights before and after the treatment is no more than 0.2 mg, and the weighing accuracy is accurate to 0.1 mg. 2.5 The blank test must be carried out simultaneously with the sample analysis steps, and the analysis results must be corrected with the reagent blank value. 2.6 When the acid-insoluble matter is less than 2%, take the acid solution to determine sulfur trioxide (SO.), calcium oxide (CaO), magnesium oxide (MgO), aluminum oxide (Al.O,), and ferric oxide (Fe.0:); when the acid-insoluble matter is greater than 2%, use the alkali fusion solution to determine sulfur trioxide (SO,), calcium oxide (CaO), magnesium oxide (MgO), aluminum oxide (Al.O,), ferric oxide (Fe2O,), titanium dioxide (TiO,), and silicon dioxide (Si,).
2.7 The analysis results are expressed in percentages. The difference between the parallel determination results is not greater than the analytical tolerance specified in this standard. When the sum of all components in the full analysis is between 99.50 and 100.50, the average value is allowed to be reported as the result. 2.8 The test report should include the following contents:
Submitting unit, sampling person, and date of submission; sample name, number, and required analysis items; standard number and name of the analysis method;
Analysis results:
Signatures of the analyst and reviewer, and seal of the analysis unit; Date of result reporting;
Other explanations related to the analysis results.
3 Reagents
3.12N hydrochloric acid.
3.21% silver nitrate solution.
3.31:1 ammonium hydroxide.
3.41:1 hydrochloric acid.
3.52% EDTA solution Approved by the Ministry of Light Industry of the People's Republic of China on January 15, 1993, and implemented on September 0, 198
3.610% chloramine solution.
3.70.2% methyl red ethanol solution.
3.80.5% hydrochloric acid.
3.930% triethanolamine.
3.1025% potassium hydroxide solution.
3.11 Calcium carbonate: high-grade pure.
QB/T 1641—1992
3.12 Calcein mixed indicator: weigh 20g potassium chloride, add 0.2g calcein, 0.12g thymol blue, grind finely, fill with water, and store in a ground-mouth weighing bottle (these three reagents must be dried at 105-110°C). 3.13 0.01M disodium ethylenediaminetetraacetic acid solution. 3.14 Calcium oxide standard solution: 1mL contains 1mg calcium oxide. Accurately weigh 0.8924g of high-grade pure calcium carbonate that has been dried at 105-110°C for 2h, place in a 500ml beaker, add 50ml of water, add 20mL of 1:1 hydrochloric acid dropwise, heat to completely dissolve the calcium carbonate, cool to room temperature, transfer to a 500mL volumetric flask, dilute to scale with water, and shake the bottle.
3.15 Calibration method of calcium oxide standard solution Pipette 10mL of the solution in 3.14 into a 250mL beaker, add 100mL of water, 5mL of 30% triethanolamine, and 20mL of 20% potassium hydroxide. Stir the solution with a glass rod, add an appropriate amount of calcein mixed indicator, and titrate with 0.01MEIDTA solution against a black background until the green fluorescence disappears and turns purple-red. Record the milliliters of EDTA consumed V. The titer of EDTA standard solution to calcium oxide is calculated according to formula (1). W
Tceo =V
Where: Tcar--1mLEDTA standard solution is equivalent to milligrams of calcium oxide; W---milligrams of calcium oxide absorbed;
V--milliliters of EDTA consumed.
3.16 Acid chrome blue K-naphthol green B mixed indicator Weigh 20g potassium chloride, add 0.16g acid chrome blue K, add 0.48g naphthol green B in a porcelain mortar, grind and mix, and store in a ground-mouth weighing bottle (these three reagents are dried at 105-110°C). 3.17 The titer of EDTA standard solution on magnesium oxide is calculated according to formula (2). 40.32
T'Mgo = Tcao X
Where: Tmn—-1mEDTA standard solution is equivalent to the number of milligrams of magnesium oxide; 40.32 Molecular weight of magnesium oxide
Molecular weight of calcium oxide.
56. 08--—
3.18 0.1% p-nitrophenol.
3.19 0.2% dimethylphenol orange.
3.20 pH ~ 6 acetic acid-ammonium acetate buffer solution. 3.21 0.01M zinc acetate solution.
(2)
3.22 Lead aluminum trioxide standard solution: 1 ml contains 1 mg aluminum trioxide. Accurately weigh 9.3052 g of high-grade pure potassium aluminum sulfate CKA (SO4) 2·12H.0 that has been dried in a desiccator, put it in a beaker, dissolve it and transfer it to a 1000ml volumetric flask, dilute it with water to the scale, and shake it well: 3.23 Calibration of the volume ratio K value when the EDTA standard solution and the zinc acetate standard solution are dropped. Accurately transfer 20 mL of 0.01M EDTA standard solution to a 250 mL conical flask, add 50 mL of water, 5 mL of pH=6 acetic acid-ammonium acetate buffer solution, and 1-2 drops of 0.2% dimethylphenol orange indicator. Titrate with 0.01M zinc acetate standard solution until the solution turns slightly red as the end point, and record the volume V of the consumed 0.01M zinc acetate standard solution. K is calculated according to formula (3). 199
QB/T 1641-1992
K = 20/V
Where: K----1 mL of zinc acetate standard solution is equivalent to the volume of EDTA standard solution (i.e. the volume ratio when dropping), mL: the number of milliliters of zinc acetate standard solution consumed. 3.24 Calibration of the titration degree T of EDTA standard solution on aluminum oxide. 3)
Accurately pipette 5 ml of aluminum oxide standard solution and 20 ml of 0.01 M EDTA standard solution into a 250 ml conical flask, add water to about 100 ml, add 5 ml of acetic acid-ammonium acetate buffer solution, and follow the steps of K calibration in 3.23. Record the volume Vi of 0.01 M zinc acetate standard solution consumed, and calculate the titer T according to formula (4). 5XC
W: (----concentration of aluminum oxide standard solution, mg/mL; K.-conversion factor in 3.23;
W: ---0.01 M zinc acetate standard solution consumed in milliliters. 3.252% ascorbic acid (freshly prepared). 3.261 M citric acid.
3.270.1 N acetic acid solution.
3.280.1 N sodium acetate solution.
3.29 pH ~ 3 acetic acid-sodium acetate buffer solution. 3.30 0.4% o-phenanthroline solution.
3.31 Ferric oxide standard solution: 1 mL contains 0.01 mg of ferric oxide. ?(4)
Accurately weigh 0.4911 g of high-grade pure ammonium ferrous sulfate [FeSO. * (NH) SO4·6H,O] in a 250 mL beaker, add: 1:1 sulfuric acid 10 mL, 50ml of water, heat to dissolve, cool to room temperature, transfer to a 1000mL volumetric flask, dilute to scale with water, pipette 50mL of this solution into a 500ml volumetric flask, dilute to scale, and shake well. 3.321N sulfuric acid.
3.335% diaminopyroline methane 1N hydrochloric acid solution. 3.34 Titanium dioxide standard solution: 1mL contains 0.01mg titanium dioxide. Accurately weigh 0.1g titanium dioxide, add 1g potassium pyrosulfate to melt, cool and dissolve with 1N sulfuric acid, weigh into a 1000mL volumetric flask, dilute to scale with 1N sulfuric acid and shake, use a pipette to transfer 10mL of this solution into a 100mL volumetric flask, dilute to scale with water, and shake well. 3.3510% sodium hydroxide solution.
3.3610% ammonium molybdate solution.
3.3710% ascorbic acid solution (freshly prepared). 3.38Silicon dioxide: high purity.
3.391N hydrochloric acid.
3.4095% ethanol
3.410.2% potassium permanganate solution.
3.42Silicon dioxide standard solution: 1mL contains 0.1mg silicon dioxide. Accurately weigh 0.1g of silicon dioxide that has been calcined at 1000℃ for 1h, place it in a platinum crucible, add 2g of anhydrous sodium carbonate, mix and heat at 1000℃ until completely melted, wash into a beaker after cooling, heat to dissolve, transfer to a 1000mL volumetric flask and dilute to the scale, shake well, and store in a plastic bottle.
3.43Preparation of potassium oxide standard stock solution: each milliliter contains 1mg potassium oxide. Accurately weigh 1.5830g of potassium chloride dried at 105-110C for 2h, place it in a beaker, add water to dissolve, transfer to a 1L volumetric flask, dilute to scale with water, and shake well.
3.44 Preparation of sodium oxide standard stock solution: each milliliter contains 1mg sodium oxide. Accurately weigh 1.8858g of sodium chloride dried at 105-110C for 2h, place it in a beaker, add water to dissolve, transfer to a 1L volumetric flask, dilute to scale with 200
water, and shake well.
QB/T 1641—1992
3.45 Preparation of potassium oxide standard solution: 1ml contains 0.01mg potassium oxide. Accurately transfer 10ml of the stock solution in 3.43 to a 100ml volumetric flask, dilute to scale with water, and shake well. 3.46 Preparation of sodium oxide standard solution: 1 mL contains 0.01 mg sodium oxide. Accurately pipette 2 mL of the stock solution in 3.44 into a 200 mL volumetric flask, dilute to the mark with water, and shake well. 4 Instruments
4.1 Atomic absorption spectrophotometer
The sensitivity of potassium at a wavelength of 7665 mm is higher than 0.03 μg/mL (1% absorption); the sensitivity of sodium at 5890 mm is higher than 0.01 μg/mL (1% absorption).
4.2 Flame spectrophotometer
Sensitivity: Potassium (K) 0.01 mg/mL (10 ppm) causes the indicator to deflect 100 divisions: Sodium (Na) 0.02 mg/mL (20 ppm) causes the indicator to deflect 100 divisions.
4.3 Spectrophotometer
Sensitivity: 0.012~0.01A/3ppm, graduation value 0.01, measuring range 400~700mm. 4.4 Analytical balance: graduation value 0.1mg.
4.5 Controllable high temperature box-type resistance furnace: rated temperature: above 1000℃. 4.6 Pharmaceutical balance: sensitivity 0.1g
4.7 Adjustable electric heating furnace plate.
4.8 Electric distilled water device.
4.9 Adjustable electric hot water bath.
4.10 Controllable electric heating drying oven: sensitivity ±1℃. 5.1 The samples to be tested shall all pass through a standard sieve with a pore size of 0.45 mm. The weight shall not be less than 50 g and shall be placed in a ground-mouth bottle. Before the test, the samples shall be mixed and reduced to 15 g by quartering. Grind in an agate mortar until all of them pass through a standard sieve with a pore size of 0.15 mm. Mix thoroughly and place in a weighing bottle for later use.
5.2 The analysis samples shall be placed in an oven at (40 ± 4)°C for 3 hours, then placed in a desiccator and cooled to room temperature for analysis. 5.3 Preparation of acid-soluble sample solution
Accurately weigh about 1g of the sample in 5.2, put it in a 250mL beaker, moisten it with water, cover it with Table III, slowly add 50mL of 2N hydrochloric acid, and after the reaction stops, wash the table and the wall of the beaker with water, heat and boil for 3~5min, keep it warm in a boiling water bath for 1h, remove it, add 10:mL of hot water, filter it with dense filter paper while it is hot into a 250ml volumetric flask, and wash it with hot water until there is no chloride ion (check with silver nitrate solution), dilute to the scale, shake well and set aside. This solution is A. 5.4 Preparation of alkali fusion sample solution
Accurately weigh about 1g of the sample in 5.2, place it in a silver crucible pre-melted with 4B sodium hydroxide, first bake it at low temperature, then melt it at 600~650C, after cooling, wash it into a 250mL beaker with hot water, then pour it into a beaker pre-filled with 20ml.1:1 molten acid, after melting, transfer it into a 250ml volumetric flask, dilute to the scale, and shake well. This solution is B. 6 Determination of adsorbed water
6.1 Method summary
Since the combination of calcium sulfate and water molecules in natural gypsum is not very strong, the temperature at which calcium sulfate dihydrate loses crystal water is relatively low. Generally, it starts to discharge crystal water above 8C℃, so the determination of gypsum attached water molecules is carried out at about 40C. 6.2 Analysis steps
QB/T 1641-1992
Accurately weigh about 2g of the sample in 5.1, put it into a weighing bottle that has been dried to constant weight, put it in an oven at (40 ± 4)°C for 2h, take it out, cover it with a ground stopper, cool it to room temperature in a desiccator and weigh it, and dry it repeatedly (re-drying for 1h) until constant weight. 6.3 Calculation
Calculate the percentage of adsorbed water according to formula (5). Adsorbed water (%) = G × 100
Where: G—the mass of the sample plus the weighing bottle before drying, g; G---the mass of the sample plus the weighing bottle after drying.
G——the mass of the sample before drying, g.
7 Determination of crystal water
7.1 Method summary
...(5)
The crystal water in natural gypsum is loosely combined with calcium sulfate. Under normal circumstances, the crystal water is basically eliminated at a temperature of about 180°C. The temperature at which pure and well-crystallized gypsum excretes crystal water is slightly higher. Therefore, the determination of crystal water in gypsum is carried out at about 230°C. 7.2 Analysis steps
Accurately weigh about 2g of the sample in 3.2, place it in a constant-weight platinum (or porcelain crucible), burn it at (230±5)°C for 45min, take it out and move it to a desiccator, cool it to room temperature and weigh it, and burn it repeatedly (re-burning is 30min) until constant weight. 7.3 Calculation
The percentage of crystal water is calculated according to formula (6).
Crystallization water (%) = 9
Where: (, -- mass of sample before calcination plus mass of village + g; G-mass of sample after calcination plus mass of crucible·g: G
mass of sample before calcination, name.
8 Determination of acid-insoluble matter
8.1 Summary of method
The sample is dissolved in 2-hydrochloric acid and the residue is calcined at 950-1000℃ to constant weight, which is the acid-insoluble matter. 8.2 Analysis steps
(6)
Perform the steps in 5.3 and transfer the obtained precipitate together with the filter paper into a platinum crucible (or porcelain crucible) of constant weight. After low-temperature calcination, place it in a high-temperature furnace and heat it from room temperature to 950-1000℃ for 1 h, take it out, put it in a desiccator, cool it to room temperature, weigh it, and burn it repeatedly (re-burning for 30 minutes) until constant weight.
8.3 Calculation
Acid insoluble matter is calculated according to formula (7)
Acid insoluble matter (%)=
Where: G. Crucible mass g,
G. Residue mass after burning plus crucible mass·g: G—. Sample mass, g.
9 Determination of sulfur trioxide
·(7)
9.1 Summary of the method
Take an acid-soluble or alkali-soluble test solution, complex iron with EDTA, precipitate sulfur with barium chloride in a hydrochloric acid solution, burn it at 800C to constant weight, and then 202
QB/T 1641--1992
Convert the weight of barium sulfate into sulfur trioxide content. 9.2 Analysis steps
Pipette 5mL of solution A or B with methyl red as indicator, adjust with 1:1 ammonium hydroxide until the solution turns yellow. Add 10mL of 1:1 hydrochloric acid. Dilute with water to 300mL, heat to boil, slowly add 15~20mL of 10% barium chloride, boil for 3~5min, remove and place overnight, filter with dense filter paper, wash the beaker and precipitate 34 times with 0.5% hydrochloric acid, and Transfer all the precipitate onto filter paper, wash the precipitate with hot water until there is no chloride ion (check with silver nitrate solution), transfer the precipitate and filter paper into a porcelain crucible with constant weight, incinerate at low temperature, place in a high temperature furnace and heat from room temperature to 800°C and keep warm for 1 hour, take out, place in a desiccator and cool to room temperature, weigh, burn repeatedly (re-burn for 30 minutes! until constant weight, and perform a reagent blank test, deduct the blank test value from the obtained barium sulfate weight. 9.3 Calculation
The percentage of sulfur trioxide is calculated according to formula (8). SO;(%) = (G, - G - G) X 0. 343 0 × FG
Wherein: G. - reagent blank mass·g;
G--crock mass.;
G.---precipitate after burning and crucible mass·g: G--sample mass·g;
F---ratio of total volume to volume of sample solution; 0.3430-conversion coefficient of barium sulfate to sulfur trioxide. 10 Determination of calcium oxide and magnesium oxide
10.1 Method summary
× 100
Use triethanolamine to mask iron and aluminum. In a solution with pH ~ 12.5, use calcein as an indicator and titrate calcium with EDTA standard solution. When pH is 10, add acid chrome blue K-naphthol green B mixed indicator and use EDTA standard solution to titrate the total amount of calcium and magnesium. The amount of magnesium is obtained by subtracting the difference between the total amount.
10.2 Analysis steps
10.2.1 Determination of calcium oxide
Accurately transfer 10mL of solution A or B into a 250mL beaker and add 100mL of water, 5ml of 30% triethanolamine and 20ml of 20% potassium hydroxide. After stirring the solution with a glass rod, add an appropriate amount of calcein mixed indicator, and titrate with 0.01M EDTA standard solution against a black background until the green fluorescence disappears and turns purple-red, which is the end point. Record the consumed EDTA milliliters V1. 10.2.2 Calculate the percentage of calcium oxide according to formula (9). CaO (%) =
Tco ×Vi×
GX 1 000
Wherein: V---the number of milliliters of EDTA consumed when titrating calcium oxide; Tcao-the titer of EDTA standard solution on calcium oxide, mg/mL; F--the ratio of total volume to the volume of the test solution; G--the mass of the sample, g.
10.2.3 Determination of magnesium oxide
Accurately transfer 10 ml of solution A or B into a 250 ml beaker, add 40 ml of water, 5 ml of 30% triethanolamine, and 40 ml of 1/1 ammonium hydroxide, stir well, add an appropriate amount of acid chrome blue K-naphthol green B mixed indicator, and titrate with 0.01 M EDTA standard solution until a pure blue color appears, which is the end point. The number of milliliters of EDTA standard solution consumed at this time is the total amount of calcium and magnesium titrated V?. Subtract the number of milliliters of EDTA standard solution consumed when titrating calcium oxide from this total amount, which is the actual consumption of magnesium oxide. 10.2.4 Blank test of water and reagents
QB/T 1641-1992
Take 50 mL of distilled water. Follow the titration steps in 102.3 and record the milliliters of EDTA consumed V. 10.2.5 Calculation
Calculate the percentage of magnesium oxide according to formula (10). Mgo(%) = (VV-Vo)x TM × E
G × 1 000
In the formula, V is the milliliters of EDTA standard solution consumed when titrating calcium oxide; V is the milliliters of EDTA standard solution consumed when titrating calcium and magnesium; V is the milliliters of EDTA standard solution consumed in the blank test T is the titer of EDTA standard solution on magnesium oxide, ng/mLF—the ratio of the total volume to the volume of the test solution; G is the mass of the sample in g.
11 Determination of aluminum oxide
11.1 Summary of the method
-( 10 )
Take solution A or B, add excess EDTA standard solution, use xylenol orange as indicator and back-titrate with zinc acetate standard solution to the end point
11.2 Analysis steps
Accurately transfer 50mL of solution A or B into a 250mL conical beaker, add 20mL of 0.01M EDTA standard solution, add 50mL of water and heat to 60~70℃, add 1 drop of 0.1% p-nitrophenol, adjust to yellow with 1:1 ammonium hydroxide, and then adjust to colorless with 1:1 hydrochloric acid, add 5mL of ammonium acetate buffer solution, heat and boil for 2~3min, cool, add 1~2 drops of 0.2% xylenol orange, and titrate with 0.01M zinc acetate standard solution until the solution turns slightly red as the end point, and record the number of milliliters of 0.01M zinc acetate standard solution consumed. V11.3 Calculation
The percentage of aluminum oxide is calculated according to formula (11). A1,0,() -
W -- VDKTALO, XF
× 100 -- (Fe,0, + Ti02) X 0. 638 7 ****(11 )GX 1 000
Wherein: V is the milliliters of zinc acetate standard solution consumed in the blank test; V,—the milliliters of zinc acetate standard solution consumed in the titration test; TA,u-the titer of EDTA standard solution against aluminum oxide; K.The number of milliliters of EDTA standard solution equivalent to 1mL zinc acetate standard solution G---sample mass.g:
F.The ratio of the total volume to the volume of the test solution taken. 12 Determination of ferric oxide
12.1 Summary of method
Take solution A or B, shield the coexisting ions with citric acid, reduce the trivalent iron to divalent iron with ascorbic acid, and then in a solution with pH ~ 3, o-phenanthroline and Fe2- form an orange-red complex. Measure its absorbance at a wavelength of 510nm with a spectrometer and check its content on the drawn standard curve.
12.2 Analysis steps
12.2.1 Drawing of standard curve
Pipette 0.1, 2.3, 4.57, 9mL of the solution in 3.32 into a 100mL volumetric flask, add 5ml of 2% ascorbic acid solution, shake well. After 10 minutes, add 3mL of 1M citric acid and 1-2 drops of 0.1% p-nitrophenol, adjust to yellow with 1:1 ammonium hydroxide, add 1:1 hydrochloric acid until the yellow color of the solution disappears, add 5mL of pH 3 acetic acid-sodium acetate buffer solution and 3mL of 0.4% o-phenanthroline, dilute to the scale with water, shake well, stand for 10 minutes, and perform colorimetry at 510nm on a spectrophotometer with a 3cm colorimetric channel and the reagent blank solution as a reference. Measure the absorbance at 204
and draw an absorbance-concentration curve. 12.2.2 Determination of sample
QB/T 1641—1992
Accurately transfer 25 mL of solution A or B into a 100 mL volumetric flask, and perform the following operations according to the steps for drawing the standard curve. 12.3 Calculation
The percentage of ferric oxide is calculated according to formula (12). C×F
G×1000×100
Fe,O.(%) =
Wherein: C—the number of milligrams of ferric oxide found on the standard curve, F——the ratio of the total volume to the volume of the test solution taken, and G—the mass of the sample·g.
13 Determination of titanium dioxide
13.1 Method summary
(12)
In hydrochloric acid medium, diaminopyridine methane (DAPM) forms a yellow complex with titanium ions. Add ascorbic acid to eliminate the interference of iron ions. Use a spectrophotometer to measure its absorbance at a wavelength of 390nm, and check its content on the drawn curve. 13.2 Analysis steps
13.2.1 Drawing of standard curve
Accurately pipette 0.1.2.3,4.5? ml titanium dioxide standard solution is placed in a 100mL volumetric flask, and 1N sulfuric acid is added to 7mL. After shaking and standing for 5 minutes, 20mL of 2V hydrochloric acid and 5mL of 5% diaminopyridine methane are added, and diluted to the scale with water, and shaken. After 1 hour, the absorbance is measured at 390nm on a spectrophotometer with 2cm colorimetric blood, and the reagent blank solution is used as a reference, and the absorbance·concentration curve is drawn.
13.2.2 Determination of sample
Accurately transfer 25mL of B solution and place it in a 100mL volumetric flask, add 5mL of 2% ascorbic acid, and perform the following operations according to the steps for drawing the standard curve.
13.3 Calculation
The percentage of titanium dioxide is calculated according to formula (13). CXF
TiO2(%) = GX1 000
Wherein: C—milligrams of titanium dioxide found on the standard curve; F—ratio of total volume to volume of test solution; G—mass of sample in g.
14 Determination of silicon dioxide
14.1 Summary of method
Silicic acid can react with ammonium molybdate to form a yellow silicomolybdic acid complex in a weakly acidic solution. This yellow complex can be reduced to molybdenum salt by ascorbic acid. Use a spectrophotometer to measure its absorbance at a wavelength of 650nm and check its content on the drawn curve. 14.2 Analysis steps
14.2.1 Drawing of standard curve
Accurately transfer 0, 0.5, 1, 2.3.4mL of the standard solution in 3.43 to a 100mL volumetric flask, add 5mL of 1N hydrochloric acid, 8mL of 95% ethanol, 3mL of 10% ammonium molybdate, dilute with water to about 50mL, and add 1 drop of 0.2% potassium permanganate. Place at 20~30℃ for 15min, then add 10mL of 1:1 hydrochloric acid, add water to 80mL, add 3mL of ascorbic acid, dilute with water to the scale, shake, and after 1h, measure the absorbance at 650hm on the spectrophotometer with a 1cm colorimetric book and use the reagent blank solution as a reference, and draw the absorbance-concentration curve.
14.2.2 Determination of sample
QB/T 1641-1992
Accurately transfer 10mL of solution B into a 100mL volumetric flask and add 1-2 drops of p-nitrophenol. Adjust with 10% sodium hydroxide until it turns yellow, adjust with 1V hydrochloric acid until the yellow color of the solution just disappears and the excess is 5mL, add 8mL of 95% ethanol, and perform the following operations according to the steps for drawing the standard curve.
14.3 Calculation
Calculate the percentage of silicon dioxide according to formula (14). C×F
G×1000×100
SiO,(%)
Wherein: (--the number of milligrams of silicon dioxide found on the standard curve: F--the ratio of the total volume to the volume of the test solution; G--the mass of the sample·g.
15 Determination of potassium oxide and sodium oxide
The determination of potassium oxide and sodium oxide adopts the following two methods. 15.1 Atomic absorption spectrophotometry
15.1.1 Summary of the method
.........( 14 )
After the sample is dissolved in hot water, the filtrate is measured on an atomic absorption spectrophotometer with a potassium hollow cathode lamp at a wavelength of 7665nm and a sodium hollow cathode lamp at a wavelength of 5890nm for the absorbance of potassium and sodium, respectively. 15.1.2 Analysis steps
15.1.2.1 Drawing of potassium and sodium standard curves From 3.46, 0, 0.5.12.3, 4, 5.6, 7, 8 ml of potassium standard solution and 0.1, 2, 3, 4.5, 6, 8.10, 20 ml of sodium standard solution are drawn and analyzed. Place in a 100mL volumetric flask, add 10mL of calcium standard solution (1mL contains 1mg calcium oxide), dilute to the mark with water, and use a potassium hollow cathode lamp at a wavelength of 7665nm, a sodium hollow cathode lamp at a wavelength of 5890nm, and an acetylene-air flame on an adjusted atomic absorption spectrophotometer. Use 0 standard solution as a reference to measure their absorbances and draw concentration-absorbance standard curves for potassium oxide and sodium oxide. 15.1.2.2 Instrument measurement conditions
Instrument measurement conditions should meet the requirements of Table 1.
Determination of elements
15.1.2.3 Preparation of test solution
Determination wavelength, nm
Flame type
Air-acetylene
Air-acetylene
Flame state
Lean flame
Lean flame
Accurately weigh 1-1.5 g of the sample in 5.2 and place it in a 250 mL beaker. Add 50 mL of hot water and heat until boiling. Remove the beaker and let stand for 5 min. Filter with medium-speed filter paper into a 100 mL volumetric flask. Wash with warm water several times, discard the residue, and use Dilute with water to the mark, shake well, and store in a plastic bottle.
15.1.2.4 Determination of the sample
The sample solution in 15.1.2.3 is measured according to the same steps and conditions as 15.1.2.1 and 15.1.2.2, and the absorbance of potassium and sodium is measured with the reagent blank solution as a reference. The content of potassium oxide and sodium oxide is calculated by the standard curve method or the close interpolation method. 15.1.3 Calculation
15.1.3.1 The concentration C of potassium oxide and sodium oxide in the sample is calculated by the close interpolation method according to formula (15). (C, - C)(A - A) + C.
A, - A
·（15）
QB/T 1641-1992
Wherein: C,—concentration of potassium oxide and sodium oxide in the test solution, μg/mL; C.—concentration of potassium oxide and sodium oxide in the first standard solution, μg/mL; C2---concentration of potassium oxide and sodium oxide in the second standard solution, μg/mL, A.——·absorbance of the first standard solution; A--absorbance of the second standard solution;
Ax——absorbance of the test solution.
15.1.3.2 The percentage of potassium oxide and sodium oxide in the sample is calculated according to formula (16). K,0(Na.0)% =
G × 1 000
Wherein: C----the concentration of potassium oxide and sodium oxide found on the standard curve (or the concentration found by close interpolation) ·μg/mL; V—the volume of the test solution.mL
F——the ratio of the total volume to the volume of the test solution taken; G—the mass of the sample, g.
15.2 Flame photometry
15.2.1 Summary of the method
（16）
After the test solution is dissolved in hot water, the absorbance of potassium and sodium is determined by a flame photometer, and compared with the standard curve to determine the content of potassium and sodium. 15.2.2 Analysis steps
15.2.2.1 Drawing standard curves for potassium oxide and sodium oxide. Accurately pipette 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8 mL of potassium standard push solution from Article 3.46 and 1, 1, 2, 3, 4.5, 6.8, 10.20 mL of sodium standard push solution from Article 3.47 and place them in 100 mL volumetric flasks respectively. Add 10 mL of calcium standard solution (1 mL contains 1 mg of calcium oxide) and dilute to the scale with water. When measuring potassium on the adjusted flame photometer, use a potassium filter and when measuring sodium, use a sodium filter. Using the blank standard solution as a reference, determine the current values of potassium oxide and sodium oxide on the galvanometer respectively. Use the galvanometer reading as the ordinate and the concentrations of potassium oxide and sodium hydride as the abscissa, and draw the galvanometer reading-concentration curves respectively. 15.2.2.2 Determination of the sample
Use the test solution in 15.1.2.3 in the same way as in 15.2.2.1, and use the reagent blank as a reference to determine the current value of potassium oxide and sodium oxide. Calculate the content of potassium oxide and sodium oxide using the standard curve or the close interpolation method. 15.2.3 Calculation
15.2.3.1 The calculation of the concentration C of potassium oxide and sodium oxide in the sample using the close interpolation method shall be calculated in accordance with 15.1.3.1. 15.2.3.2 The calculation of the percentage of potassium oxide and sodium oxide in the sample shall be calculated in accordance with 15.1.3.2. 16 Allowable error of analysis results
The allowable error of the analysis results shall comply with the provisions of Table 2. Table 2
Measurement Items
Absorbed Water (H2O)
Crystallized Water (H,O)
Acid Insoluble Matter
Content Range.%
Allowance, %
Measurement Items
Additional Notes:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Ceramic Standardization Center. QB/T1641--1992
Continued Table 2
Content Range, %
This standard is drafted by the Ceramic Industry Science Research Institute of the Ministry of Light Industry. The main drafters of this standard are Yao Jilie, Zhang Maosen and Li Shuo. Allowance, %
From the date of implementation of this standard, the former Ministry of Light Industry standard QB972-1986 "Chemical Analysis Method for Gypsum for Daily Ceramics" will be invalid. 2083 Preparation of test solution
Measurement wavelength, nm
Flame type
Air-acetylene
Air-acetylene
Flame state
Lean flame
Lean flame
Accurately weigh 1-1.5 g of the sample in 5.2 and place it in a 250 mL beaker. Add 50 mL of hot water and heat until boiling. Remove the beaker and let it stand for 5 min. Filter with medium-speed filter paper into a 100 mL volumetric flask. Wash several times with warm water, discard the residue, dilute to the scale with water, shake well, and store in a plastic bottle.
15.1.2.4 Determination of Samples
Use the sample solutions in 15.1.2.3 in the same manner and under the same conditions as in 15.1.2.1 and 15.1.2.2, respectively, and use the reagent blank solution as a reference to determine the absorbance of potassium and sodium, and calculate the contents of potassium oxide and sodium oxide by the standard curve method or the close interpolation method. 15.1.3 Calculation
15.1.3.1 Use the close interpolation method to calculate the concentrations C of potassium oxide and sodium oxide in the sample according to formula (15). (C, - C)(A - A) + C.
A, - A
·（15）
QB/T 1641-1992
Wherein: C,—concentration of potassium oxide and sodium oxide in the test solution, μg/mL; C.—concentration of potassium oxide and sodium oxide in the first standard solution, μg/mL; C2---concentration of potassium oxide and sodium oxide in the second standard solution, μg/mL, A.——·absorbance of the first standard solution; A--absorbance of the second standard solution;
Ax——absorbance of the test solution.
15.1.3.2 The percentage of potassium oxide and sodium oxide in the sample is calculated according to formula (16). K,0(Na.0)% =
G × 1 000
Wherein: C----the concentration of potassium oxide and sodium oxide found on the standard curve (or the concentration found by close interpolation) ·μg/mL; V—the volume of the test solution.mL
F——the ratio of the total volume to the volume of the test solution taken; G—the mass of the sample, g.
15.2 Flame photometry
15.2.1 Summary of the method
（16）
After the test solution is dissolved in hot water, the absorbance of potassium and sodium is determined by a flame photometer, and compared with the standard curve to determine the content of potassium and sodium. 15.2.2 Analysis steps
15.2.2.1 Drawing standard curves for potassium oxide and sodium oxide. Accurately pipette 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8 mL of potassium standard push solution from Article 3.46 and 1, 1, 2, 3, 4.5, 6.8, 10.20 mL of sodium standard push solution from Article 3.47 and place them in 100 mL volumetric flasks respectively. Add 10 mL of calcium standard solution (1 mL contains 1 mg of calcium oxide) and dilute to the scale with water. When measuring potassium on the adjusted flame photometer, use a potassium filter and when measuring sodium, use a sodium filter. Using the blank standard solution as a reference, determine the current values of potassium oxide and sodium oxide on the galvanometer respectively. Use the galvanometer reading as the ordinate and the concentrations of potassium oxide and sodium hydride as the abscissa, and draw the galvanometer reading-concentration curves respectively. 15.2.2.2 Determination of the sample
Use the test solution in 15.1.2.3 in the same way as in 15.2.2.1, and use the reagent blank as a reference to determine the current value of potassium oxide and sodium oxide. Calculate the content of potassium oxide and sodium oxide using the standard curve or the close interpolation method. 15.2.3 Calculation
15.2.3.1 The calculation of the concentration C of potassium oxide and sodium oxide in the sample using the close interpolation method shall be calculated in accordance with 15.1.3.1. 15.2.3.2 The calculation of the percentage of potassium oxide and sodium oxide in the sample shall be calculated in accordance with 15.1.3.2. 16 Allowable error of analysis results
The allowable error of the analysis results shall comply with the provisions of Table 2. Table 2
Measurement Items
Absorbed Water (H2O)
Crystallized Water (H,O)
Acid Insoluble Matter
Content Range.%
Allowance, %
Measurement Items
Additional Notes:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Ceramic Standardization Center. QB/T1641--1992
Continued Table 2
Content Range, %
This standard is drafted by the Ceramic Industry Science Research Institute of the Ministry of Light Industry. The main drafters of this standard are Yao Jilie, Zhang Maosen and Li Shuo. Allowance, %
From the date of implementation of this standard, the former Ministry of Light Industry standard QB972-1986 "Chemical Analysis Method for Gypsum for Daily Ceramics" will be invalid. 2083 Preparation of test solution
Measurement wavelength, nm
Flame type
Air-acetylene
Air-acetylene
Flame state
Lean flame
Lean flame
Accurately weigh 1-1.5 g of the sample in 5.2 and place it in a 250 mL beaker. Add 50 mL of hot water and heat until boiling. Remove the beaker and let it stand for 5 min. Filter with medium-speed filter paper into a 100 mL volumetric flask. Wash several times with warm water, discard the residue, dilute to the scale with water, shake well, and store in a plastic bottle.
15.1.2.4 Determination of Samples
Use the sample solutions in 15.1.2.3 in the same manner and under the same conditions as in 15.1.2.1 and 15.1.2.2, respectively, and use the reagent blank solution as a reference to determine the absorbance of potassium and sodium, and calculate the contents of potassium oxide and sodium oxide by the standard curve method or the close interpolation method. 15.1.3 Calculation
15.1.3.1 Use the close interpolation method to calculate the concentrations C of potassium oxide and sodium oxide in the sample according to formula (15). (C, - C)(A - A) + C.
A, - A
·（15）
QB/T 1641-1992
Wherein: C,—concentration of potassium oxide and sodium oxide in the test solution, μg/mL; C.—concentration of potassium oxide and sodium oxide in the first standard solution, μg/mL; C2---concentration of potassium oxide and sodium oxide in the second standard solution, μg/mL, A.——·absorbance of the first standard solution; A--absorbance of the second standard solution;
Ax——absorbance of the test solution.
15.1.3.2 The percentage of potassium oxide and sodium oxide in the sample is calculated according to formula (16). K,0(Na.0)% =
G × 1 000
Wherein: C----the concentration of potassium oxide and sodium oxide found on the standard curve (or the concentration found by close interpolation) ·μg/mL; V—the volume of the test solution.mL
F——the ratio of the total volume to the volume of the test solution taken; G—the mass of the sample, g.
15.2 Flame photometry
15.2.1 Summary of the method
（16）
After the test solution is dissolved in hot water, the absorbance of potassium and sodium is determined by a flame photometer, and compared with the standard curve to determine the content of potassium and sodium. 15.2.2 Analysis steps
15.2.2.1 Drawing standard curves for potassium oxide and sodium oxide. Accurately pipette 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8 mL of potassium standard push solution from Article 3.46 and 1, 1, 2, 3, 4.5, 6.8, 10.20 mL of sodium standard push solution from Article 3.47 and place them in 100 mL volumetric flasks respectively. Add 10 mL of calcium standard solution (1 mL contains 1 mg of calcium oxide) and dilute to the scale with water. When measuring potassium on the adjusted flame photometer, use a potassium filter and when measuring sodium, use a sodium filter. Using the blank standard solution as a reference, determine the current values of potassium oxide and sodium oxide on the galvanometer respectively. Use the galvanometer reading as the ordinate and the concentrations of potassium oxide and sodium hydride as the abscissa, and draw the galvanometer reading-concentration curves respectively. 15.2.2.2 Determination of the sample
Use the test solution in 15.1.2.3 in the same way as in 15.2.2.1, and use the reagent blank as a reference to determine the current value of potassium oxide and sodium oxide. Calculate the content of potassium oxide and sodium oxide using the standard curve or the close interpolation method. 15.2.3 Calculation
15.2.3.1 The calculation of the concentration C of potassium oxide and sodium oxide in the sample using the close interpolation method shall be calculated in accordance with 15.1.3.1. 15.2.3.2 The calculation of the percentage of potassium oxide and sodium oxide in the sample shall be calculated in accordance with 15.1.3.2. 16 Allowable error of analysis results
The allowable error of the analysis results shall comply with the provisions of Table 2. Table 2
Measurement Items
Absorbed Water (H2O)
Crystallized Water (H,O)
Acid Insoluble Matter
Content Range.%
Allowance, %
Measurement Items
Additional Notes:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Ceramic Standardization Center. QB/T1641--1992
Continued Table 2
Content Range, %
This standard is drafted by the Ceramic Industry Science Research Institute of the Ministry of Light Industry. The main drafters of this standard are Yao Jilie, Zhang Maosen and Li Shuo. Allowance, %
From the date of implementation of this standard, the former Ministry of Light Industry standard QB972-1986 "Chemical Analysis Method for Gypsum for Daily Ceramics" will be invalid. 208%
Allowance, %
Measurement items
Additional notes:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Ceramic Standardization Center. QB/T1641--1992
Continued Table 2
Content range, %
This standard is drafted by the Ceramic Industry Science Research Institute of the Ministry of Light Industry. The main drafters of this standard are Yao Jilie, Zhang Maosen and Li Shuo. Allowance, %
From the date of implementation of this standard, the former Ministry of Light Industry standard QB972-1986 "Chemical Analysis Method of Gypsum for Daily Ceramics" will be invalid. 208%
Allowance, %
Measurement items
Additional notes:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Ceramic Standardization Center. QB/T1641--1992wwW.bzxz.Net
Continued Table 2
Content range, %
This standard is drafted by the Ceramic Industry Science Research Institute of the Ministry of Light Industry. The main drafters of this standard are Yao Jilie, Zhang Maosen and Li Shuo. Allowance, %
From the date of implementation of this standard, the former Ministry of Light Industry standard QB972-1986 "Chemical Analysis Method of Gypsum for Daily Ceramics" will be invalid. 208
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