GB/T 3045-2003 Chemical analysis methods for common abrasive silicon carbide
Some standard content:
GB/T3045--2003
This standard corresponds to ISO9286:1997 "Chemical Analysis of Abrasives and Crystalline Blocks of Silicon Carbide" (English version). The consistency between this standard and ISO9286 is non-equivalent, and the main differences are as follows: In this standard, the determination of silicon dioxide and free silicon adopts the colorimetric method; in ISO9286, the determination of silicon dioxide adopts the volumetric method, and the determination of surface silicon adopts the principle of gas generation by the reaction of silicon with sodium hydroxide; in this standard, only the weight method is used for the determination of free carbon and total carbon; in addition to the weight method, ISO9286 also adds the coulometric method; in this standard, the determination of silicon carbide adds the three-acid treatment weight method. This standard replaces GB/T3045--1989 "Chemical Analysis Methods of Silicon Carbide". Compared with GB/T3045--1989, this standard has the following major changes: a) It is written in accordance with GB/T20001.4-2001 "Standard Writing Rules Part 4: Chemical Analysis Methods"; b) The determination methods of silicon dioxide, free silicon, silicon carbide, and ferric oxide have been revised and improved; c) The determination methods of aluminum oxide, calcium oxide, and magnesium oxide have been added. This standard is proposed by the China Machinery Industry Federation. This standard is under the jurisdiction of the National Technical Committee for Standardization of Abrasives and Grinding Tools (SAC/TC139). The drafting unit of this standard: Zhengzhou Abrasives and Grinding Research Institute. The main drafters of this standard: Miao Qing, Ma Jinfeng, Wang Xu, Bao Hua. This standard was first issued in 1989.
1 Scope
Chemical analysis methods for silicon carbide, a common abrasive
GB/T3045—2003
This standard specifies the determination methods for silicon dioxide, free silicon, free carbon, total carbon, silicon carbide, ferric oxide, aluminum oxide, calcium oxide and magnesium oxide in silicon carbide abrasives and crystal blocks. This standard is applicable to the determination of chemical composition of silicon carbide abrasives and crystal blocks with a silicon carbide content of not less than 95%. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, the parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard. GB/T4676 Sampling method for common abrasives
3 Preparation of samples
3.1 Crystal block sample
Take statistically representative agglomerates, crush them until they completely pass through the 2mm sieve, mix them evenly, and use the quartering method to reduce them to 50g~60g. Continue to grind them with a steel mortar until they all pass through the 355um sieve. Use a magnet with a suction force of 9.8N~14.7N to suck out the iron in the crushing. Then mix them evenly, put them into a sample bag, dry them in an oven at 105℃~110℃ for 1h, take them out, put them in a dryer, and cool them for use. If there are strict requirements for the determination of ferric oxide, the following method should be used to prepare samples for the determination of ferric oxide: Take statistically representative crystal blocks, crush them until they completely pass through the 2mm sieve, mix them evenly, and use the quartering method to reduce them to 50g~~60g. Grind with corundum mortar until all pass through 500μm sieve, mix well, and reduce to 20g~~25g by quartering method. Grind with corundum mortar until all pass through 355um sieve, mix well, put into sample bag, dry in oven at 105℃~110℃ for 1h, take out, put into desiccator, cool and set aside. (The preparation and determination method of analytical test solution are the same as those in Chapter 8 and Chapter 9.) 3.2 Abrasive sample
For F54 (P50) and coarse samples, sampling and reduction are carried out in accordance with GB/T4676, and the rest of the operation is the same as 3.1. For F60 (P60) and fine samples, sample and reduce to 50g~60g in accordance with GB/T4676, put into sample bag, dry in oven at 105℃~110℃ for 1h, take out, put into desiccator, cool and set aside. The sample used for the determination of total carbon needs to be ground until it can all pass through the 150μm sieve. 4 Determination of silicon dioxide
4.1 Principle
The sample is treated with sodium chloride-hydrochloric acid-hydrofluoric acid to dissolve the silicon dioxide, and ammonium molybdate is added to make the silicate ions form silicomolybdenum heteropoly acid, which is reduced to silicomolybdenum blue with a 1,2.4-acid reducing agent, and its absorbance is measured at a wavelength of 700nm. 4.2 Reagents
4.2.1 Hydrochloric acid: (1+1), (1+4). 4.2.2 Ammonia water: (1+4).
4.2.3 Hydrofluoric acid: (1+1).
4.2.4 Sodium chloride solution (10%).
4.2.5 Aluminum chloride solution (45%): Weigh 90g aluminum chloride (hexahydrate) and dissolve it in water, and dilute it to 200mL with water. 4.2.6 Ammonium molybdate solution (5%): Weigh 5g of ammonium molybdate and dissolve it in water, dilute it to 100mL with water, place it for 24 hours and filter it before use; if precipitation occurs, stop using it.
4.2.7 Tartaric acid solution (10%).
4.2.8 1,2,4-acid solution (0.15%): Weigh 0.15g of 1,2,4-acid (1-amino-2-naphthol-4-sulfonic acid) and dissolve it in 20mL of sodium sulfite solution (7%), then mix it with 180mL of sodium sulfite solution (10%). The use period of this solution is two weeks. 4.2.9 p-Nitrophenol solution (0.2%). 4.2.10 Silica standard solution: 0.05mg/mL. Weigh 0.5000g of silicon dioxide (high purity reagent) burned at 1000℃ into a platinum crucible, mix it carefully with 2g of anhydrous sodium carbonate (reference reagent), cover it with 0.5g of anhydrous sodium carbonate (reference reagent), send it into a high-temperature furnace and melt it at 850℃~900℃ for 20min, take it out, cool it, wash the outer wall of the crucible, leaching it with hot water in a polyethylene beaker, transfer it to a 1000mL volumetric flask after cooling, dilute it with water to the scale, shake it well, and immediately transfer it to a clean and dry plastic bottle for storage. 1mL of this solution contains 0.5mg of silicon dioxide. Use a pipette to transfer 25mL of the above 0.5mg/mL silicon dioxide solution into a 250mL volumetric flask pre-filled with 10mL of hydrochloric acid (1+4), dilute it with water to the scale, shake it well, and it is the silicon dioxide standard solution. 1mL of this solution contains 0.05mg of silicon dioxide. 4.2.11 Blank solution: Add 1 mL of sodium chloride solution (4.2.4), 3 mL of hydrochloric acid (1+1), 3 mL of hydrofluoric acid (1+1), and 12 mL of aluminum chloride solution (4.2.5) to a polytetrafluoroethylene beaker, mix well, transfer to a 100 mL volumetric flask, dilute to the mark with water, and shake well. 4.3 Instruments and devices
4.3.1 Polytetrafluoroethylene beaker, capacity 100 mL. 4.3.2 Spectrophotometer.
4.4 Analysis steps
4.4.1 Determination
Weigh 0.2g of the sample drug accurately to 0.0001g, put it into a polytetrafluoroethylene beaker, add 1mL of sodium fluoride solution (4.2.4), 3mL of hydrochloric acid (1+1), and 3mL of hydrofluoric acid (1+1), heat it in a water bath at 80℃～90℃ for 15min～20min, cool it, add 12mL of aluminum chloride solution (4.2.5), mix it, and transfer it to a PTFE beaker. Place in a 100ml volumetric flask, dilute to scale, shake well, and after standing (micro powder samples can be dry filtered), use a pipette to transfer 10mL of the upper clear liquid to a 100mL volumetric flask, add water to the solution volume of 50mL, add 2-3 drops of p-nitrophenol solution (4.2.9) as an indicator, neutralize with ammonia water until the solution turns yellow, immediately add 5mL of hydrochloric acid (1+4), add 5mL of ammonium molybdate solution (4.2.6), and place for 15min. Add 10mL of tartaric acid solution (4.2.7) and 5mL of 1,2,4-acid solution (4.2.8), dilute to scale with water, shake well, and place for 30min. Use a 1cm colorimetric III at a wavelength of 700nm and water as a reference solution to determine its absorbance. Use the same method to perform a blank test. After subtracting the absorbance of the blank test, find out the mass of silicon dioxide on the working curve. 4.4.2 Drawing of working curve
Put 10mL of blank solution into 8 100mL volumetric flasks respectively, and then use microburette to add 0.00mL, 0.50mL, 1.00mL, 2.00mL, 4.00mL, 6.00mL, 8.00mL, 10.00mL of silica standard solution (4.2.10) into the volumetric flasks respectively, and operate according to the method of 4.4.1 below to measure the absorbance, and after subtracting the absorbance of blank solution, draw the corresponding silica mass to form a working curve.
4.5 Result calculation
The mass content of silicon dioxide (SiO2), expressed in %, is calculated according to the following formula: ×100
(SiO2)=
Wherein:
m\—the mass of the sample, in grams (g); m2—the mass of silicon dioxide found on the working curve in the sample solution, in grams (g); V,—the total volume of the test solution, in milliliters (mL); V2—the volume of the test solution, in milliliters (mL). The calculation result is accurate to 0.01.
Allowable error
Allowable error is as specified in Table 1.
Content range
>0. 25~~0. 50
>0. 50~1. 50
>1.50～3. 50
>3. 50~5. 00
5Determination of free silicon
Same laboratory
Allowable error
GB/T 3045—2003
Different laboratories
The sample is treated with sodium nitrate-nitric acid-hydrofluoric acid to dissolve silicon dioxide and free silicon, and the content is measured by the molybdenum blue absorption photometry method and converted from the content of silicon dioxide.
5.2 Reagents
5.2.1 Nitric acid: (1+1).
Hydrochloric acid: (1+4).
Hydrofluoric acid: (see 4.2.3).
Ammonia water: (see 4.2.2).
5.2.5Sodium nitrate solution (10%).
5.2.6Aluminum chloride solution: (see 4.2.5). Ammonium molybdate solution: (see 4.2.6).
5.2.8Tartaric acid solution: (see 4.2.7). 91,2,4-acid solution: (see 4.2.8). 5.2.9
5.2.10Para-nitrophenol solution: (see 4.2.9). 5.3 Apparatus and device
Same as 4.3.
5.4 Analysis steps
The operation is the same as 4.4, but the added reagent sodium chloride solution (4.2.4) 1mL is replaced by sodium nitrate solution (5.2.5) 1mL; hydrochloric acid (1+1) 3mL is replaced by nitric acid (1+1) 3mL.
5.5 Result calculation
The mass content of free silicon w(Sir), expressed in %, is calculated according to the following formula: m2
w(Sir）
Where:
The value of the sample mass, in grams (g); w(SiO2,)
X 0.467 4
m2—The value of the mass of silicon dioxide in the sample solution obtained from the working curve, in grams (g); The value of the total volume of the test solution, in milliliters (mL); Vi
The value of the volume of the test solution, in milliliters (mL). V
Calculation result is accurate to 0.01.
·（2）
GB/T 3045--2003
5.6 Allowable error
The allowable error is as specified in Table 2.
Content range
>0. 25~0. 50
>0. 50~1. 50
6 Determination of free carbon
6.1 Principle
Same laboratory
Allowable error
Different laboratories
The sample is heated at about 850℃. Silicon carbide hardly decomposes within 5 minutes, while free carbon burns to generate carbon dioxide, which is absorbed by a soda lime absorption tube. The amount of free carbon can be obtained by its weight increase. 6.2 Reagents
Sulfuric acid (density 1.84g/cm3).
6.2.2 Soda lime (granular).
6.2.3 Anhydrous calcium chloride (granular).
6.2.4 Potassium hydroxide solution (40%).
6.2.5 Glass wool: clean and dry.
6.3 Apparatus and device
Tube type carbon setting furnace, as shown in Figure 1.
1- oxygen cylinder,
—— barometer;
3- flow meter;
6- tube furnace;
7- platinum thermocouple
8- pyrometer;
9- calcium chloride tube (filled with anhydrous calcium chloride, plugged with glass wool); - gas washing bottle [fill the bottle with potassium hydroxide solution (6.2.4) to about one-third],
- concentrated sulfuric acid gas washing bottle [fill the bottle with concentrated sulfuric acid (6.2.1) to about one-third}
10, 11
soda lime (or caustic soda asbestos) and calcium chloride absorption tube (the tube is filled with two-thirds of soda lime and one-third of anhydrous calcium chloride respectively).
Schematic diagram of carbon determination device
6.4 Analysis steps
GB/T 3045—2003
Raise the temperature of the tube furnace to 850℃±10℃, install the instrument according to Figure 1, and ensure its sealing. After passing oxygen (300mL/min) for 15 minutes, weigh the mass of the carbon dioxide absorption tube (10, 11). Weigh 1g~2g of the sample, accurate to 0.0001g, place it in a high-temperature burned combustion porcelain boat, put it in the high temperature of the tube furnace, quickly connect the joints, pass oxygen (300mL/min) for 5 minutes, close the absorption tube piston and oxygen switch, remove the carbon dioxide absorption tube (10, 11) and weigh it. 6.5 Calculation of results
The mass content of free carbon w(Cr), expressed in %, is calculated according to the following formula: (ms - m2) × 0.2729 × 100
(Cp)
Wherein:
ml--the mass of the sample, in grams (g); m2
the mass of the absorption tube before combustion, in grams (g); -the mass of the absorption tube after combustion, in grams (g). The calculation result shall be accurate to 0.01.
6.6 Allowable error
The allowable error shall be in accordance with the provisions of Table 3.
Content range
Same laboratory
>0.25~0.50
>0.50～1.50
Allowable error
Different laboratory
·（3)
Note: When the laboratory does not have a tube furnace, weigh about 1g of the sample, accurate to 0.0001g, and place it in platinum blood that has been burned to constant weight. The weight loss after burning to constant weight at 750℃±10℃ can be used as an approximate value of free carbon in silicon carbide. F500 (P1000) and fine silicon carbide samples are burned at 650℃±10℃ to constant weight. If there is any weight gain, the previous weighing shall prevail or the burning time shall be shortened. Determination of total carbon
7.1 Principle
The sample is heated at high temperature in an oxygen flow with flux to completely burn the carbon and free carbon in the silicon carbide to generate carbon dioxide, which is absorbed by a soda lime absorption tube. The total carbon content can be obtained by its weight increase. 7.2 Reagents
7.2.1 Lead tetroxide: powder, burn at 500℃ for 1h, put in a desiccator to cool for use. 7.2.2 Other reagents are the same as 6.2.1~6.2.5. 7.3 Instruments and devices
Tube carbon determination furnace, as shown in Figure 1.
7.4 Analysis steps
Raise the temperature of the tube furnace to 1150℃~1200℃, install the instrument according to Figure 1, ensure its sealing, pass oxygen (300mL/min) for 15min, and weigh the mass of the carbon dioxide absorption tube (10, 11). Weigh 0.1g to 0.15g of the sample, accurate to 0.0001g, and place it in a high-temperature calcined porcelain boat. Add 2g of lead tetroxide (7.2.1) and mix well. Cover it with 1 and place it in the high-temperature part of the tube furnace. Quickly connect the joints. After passing oxygen (300mL/min) for 25 minutes, close the piston of the absorption tube and the oxygen switch, and remove the absorption tube for weighing. 7.5 Result calculation
The mass content of total carbon w(Cr), expressed in %, is calculated according to the following formula:5
GB/T3045-2003
Wherein:
w(Ct) = (m2 × 0.272 9 × 100m
mi—the mass of the sample, in grams (g); m2—the mass of the absorption tube before combustion, in grams (g); m3—the mass of the absorption tube after combustion, in grams (g). The calculation result is accurate to 0.01.
7.6 Allowable error
The allowable error is in accordance with the provisions of Table 4.
Same laboratory
8 Determination of silicon carbide
8.1 Principle
Different laboratories
The sample is treated with hydrofluoric acid-nitric acid-sulfuric acid to make free silicon and silicon dioxide generate volatile silicon tetrafluoride to escape; F400 is treated with hydrofluoric acid only as fine powder. The surface impurities are dissolved by leaching with hydrochloric acid, and the amount of residue is the content of silicon carbide (the free silicon content in F400 is subtracted from the free silicon content), or it can be calculated from the total carbon and free carbon content. 8.2 Reagents
8.2.1 Nitric acid (density 1.42g/cm).
8.2.2 Hydrofluoric acid (not less than 40%).
8.2.3 Hydrochloric acid: (1+1), (5+95).
8.2.4 Sulfuric acid: (1+1).
8.3 Analysis steps
8.3.1 Determination of F400 (P800) and coarse samples Weigh about 1g of the sample, accurate to 0.0001g, put it into platinum blood, moisten it with a small amount of water, add 2mL of nitric acid (8.2.1), 3~5 drops of sulfuric acid (1+1), and 15mL of hydrofluoric acid (8.2.2), place it on a sand bath and evaporate until the white smoke of sulfur trioxide disappears, remove it and cool it slightly, add 15mL of hydrochloric acid (1+1), heat it on a sand bath for 10min~15min to dissolve the surface impurities, cool it slightly, filter it with medium-speed quantitative filter paper, wash the platinum blood and residue with warm dilute hydrochloric acid solution (5+95) 7~8 times, collect the filtrate and washing liquid in a 250mL volumetric flask, dilute to the scale after cooling, shake well, and keep it for the determination of ferric oxide, aluminum oxide, calcium oxide, and magnesium oxide. Place the residue and filter paper in a platinum dish, incinerate at 750°C ± 10°C, cool, weigh, and repeatedly incinerate until constant weight. 8.3.2 Determination of F400 (P800) with fine sample Weigh about 1g of sample, accurate to 0.0001g, put it into platinum blood, moisten it with a small amount of water, add 10mL of hydrofluoric acid (8.2.2), evaporate it to dryness on a sand bath, add 5mL of hydrofluoric acid (8.2.2) and continue to evaporate it to dryness, keep it for 30min, take it off and cool it slightly, add 15mL of hydrochloric acid (1+1), heat it on a sand bath for 10min~15min, cool it slightly, filter it with medium-speed quantitative filter paper and a little filter paper pulp, wash the filter paper and residue with warm dilute hydrochloric acid solution (5+95) 7~8 times, collect the filtrate and washing liquid in a 250mL volumetric flask, dilute to the scale after cooling, shake well, and keep it for the determination of ferric oxide, aluminum oxide, calcium oxide, and magnesium oxide. Put the residue and filter paper into platinum blood, incinerate at 650℃±10℃ after low temperature incineration, cool, weigh, and repeat the incineration until constant weight. 8.4 Calculation of results
8.4.1 Calculation of silicon carbide mass content (SiC) of F400 (P800) and coarse sample, the value is expressed in %, calculated according to the following formula: (Sic)
m -m2 × 100
Where:
m-the value of the sample mass, in grams (g); m2-the value of the platinum blood mass, in grams (g); m3 --
the value of the mass of the residue plus the platinum blood, in grams (g). The calculation result is accurate to 0.01.
8.4.2F400(P800) Calculate the mass content of silicon carbide w(SiC) in fine sample, the value is expressed in %, and is calculated according to the following formula: w(Sic) = ma=m2 × 100 -w(Si)m
Wherein:
mt——the value of the sample mass, in grams (g); m2-——the value of the mass of platinum blood, in grams (g); the value of the mass of the residue plus platinum III, in grams (g). m3-
The calculation result is accurate to 0.01.
8.4.3 Calculate the mass content of silicon carbide w(SiC) directly based on the total carbon and free carbon content, the value is expressed in %, and is calculated according to the following formula: w(SiC) = [w(Cr) - w(C)]× 3.338 48.5 Allowable error
The allowable error shall be in accordance with the provisions of Table 5.
Same laboratory
9 Determination of ferric oxide
9.1 Principle
Different laboratories
GB/T 3045—2003
(6)
·(7)
In an ammonia solution of pH 8 to pH 11.5, ferric ions react with sulfosalicylic acid to form a yellow sulfosalicylic acid iron complex salt. The absorbance is measured at a wavelength of 420Dm to determine the ferric oxide content. 9.2 Reagents
9.2.1 Hydrochloric acid: (5+95).
9.2.2 Ammonia water: (1+1).
9.2.3 Sulfosalicylic acid solution (15%). 9.2.4 Ferric oxide standard solution: 0.1mg/ml. Weigh 0.1000g of dried ferric oxide (spectrally pure reagent) and place it in a 250mL beaker. Add 30mL of hydrochloric acid (1+1), heat to dissolve, cool and transfer to a 1000mL volumetric flask, dilute to the mark with water, shake and hook, and the standard ferric oxide solution is obtained. 1mL of the batch solution contains 0.1mg of ferric oxide.
9.2.5 Blank solution: Replace with hydrochloric acid (5+95). 9.3 Instruments and devices
Spectrophotometer.
9.4 Analysis steps
9.4.】Determination
Use a pipette to transfer 25mL of the filtrate of 8.3 into a 50mL volumetric flask, add 10mL of sulfosalicylic acid solution (9.2.3), add ammonia water (9.2.2) dropwise until it turns stable yellow, then add 3mL in excess, cool, dilute to the scale with water, shake, use water as the reference solution, use 1cm to 7
GB/T3045—2003
color blood, and determine its absorbance at a wavelength of 420nm. Use the same method to perform a blank test. After subtracting the absorbance of the blank test, check the mass of ferric oxide on the working curve.
9.4.2 Drawing of working curve
Use a pipette to transfer 10 mL of hydrochloric acid solution (5+95) into seven 50 mL volumetric flasks respectively. Then use a microburette to add 0.00 mL, 0.50 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL and 8.00 mL of ferric oxide standard solution (9.2.4) into the volumetric flasks respectively. Then operate according to the method in 9.4.1 to determine the absorbance. After subtracting the absorbance of the blank solution, draw the working curve corresponding to the corresponding mass of ferric oxide. 9.5 Calculation of results
The mass content of ferric oxide (Fe2O,), expressed in %, is calculated according to the following formula: z(Fe2O,)
Wherein:
ml——-the mass of the sample, in grams (g); m2—the mass of ferric oxide obtained from the working curve in the sample solution, in grams (g); V1-——the total volume of the filtrate prepared in 8.3, in milliliters (mL); V2—the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL). The calculation result is accurate to 0.01.
9.6 Allowable error
The allowable error is in accordance with the provisions of Table 6.
Content range
>0.25～0.50
>0. 50 ～1. 00
>1, 00～2. 50
10 Determination of aluminum oxide
10.1 Principle
Same laboratory
Allowable error
Different laboratories
Aluminum and chrome azuro blue S form a purple-red complex in a solution of pH 4 to pH 6, which is used to perform colorimetric determination of aluminum. 10.2 Reagents
10.2.1 Hydrochloric acid: (1+1), (1+20), (1+60), (5+95). 10. 2. 2
Ammonia water: (1+9).
10.2.3 p-Nitrophenol solution (0.2%). 10.2.4
Ascorbic acid solution (1%).
.(8)
Chrome azure S solution (0.05%): Weigh 0.5g of chrome azure S and dissolve it in appropriate amount of water, add 500mL of ethanol, and dilute with water to 1000mL.
10.2.6 Hexamethylenetetramine solution (20%). Aluminum standard solution: 0.005mg/mL.
Weigh 0.5000g of high-purity aluminum, place it in a plastic beaker, add 10mL of sodium hydroxide (10%), and heat in a water bath to dissolve. Add 100mL of water, add hydrochloric acid (1+1) dropwise to acidify and add 10mL in excess, cool to room temperature, transfer to a 1000mL volumetric flask, dilute with water to the mark, and shake the hook at 8
. 1mL of this solution contains 0.5mg of aluminum. GB/T3045—2003
Use a pipette to transfer 10mL of the above aluminum solution into a 1000mL volumetric flask, add 5mL of hydrochloric acid (1+1), dilute to the mark with water, and shake well to obtain the aluminum standard solution. 1mL of this solution contains 0.005mg of aluminum. 10.3 Instrument
Spectrophotometer.
10.4 Analysis steps
10.4.1 Determination
Use a pipette to transfer 2 mL of the filtrate from 8.3 into a 50 mL volumetric flask, add 10 mL of water, add 1 drop of p-nitrophenol solution (10.2.3), add ammonia water (10.2.2) until it turns yellow, add hydrochloric acid (1+20) until the yellow disappears, add 5 mL of hydrochloric acid (1+60), add 2 mL of ascorbic acid (10.2.4), 5 mL of chrome azurol S (10.2.5), and 5 mL of hexamethylenetetramine solution (10.2.6). Dilute with water to the scale, shake well, let stand for 15 minutes, use a 1 cm colorimeter, and measure its absorbance at a wavelength of 550 nm. Perform a blank test at the same time. After subtracting the absorbance of the blank test, the mass of aluminum can be found on the working curve. 10.4.2 Drawing of working curve
Use a pipette to transfer 2mL of hydrochloric acid solution (5+95) into 7 50mL volumetric flasks respectively, and then use a microburette to add 0.00mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, 5.00mL, and 6.00mL of aluminum standard solution (10.2.7) into the volumetric flasks respectively. Then, operate according to the method in 10.4.1, measure the absorbance, subtract the absorbance of the blank solution, and draw the working curve corresponding to the corresponding aluminum mass.
10.5 Calculation of results
The mass content of aluminum oxide w (Al2O), expressed in %, is calculated according to the following formula: w(Al2O3) = 1. 889 5 × -
Wherein:
ml--the value of the sample mass, in grams (g); -the value of the aluminum mass found on the working curve in the sample solution, in grams (g); m2
Vi--the value of the total volume of the filtrate prepared in 8.3, in milliliters (mL); Vz--the value of the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL). The calculation result is accurate to 0.01.
11 Determination of calcium oxide and magnesium oxide
11.1 Principle
·(9)
When the filtrate from which interfering elements such as iron and aluminum have been separated has a pH of 13, the CaO content is determined by the EDTA volumetric method using the calcium reagent sodium carboxylate as an indicator; when the pH is ~10, the total amount of CaO and MgO is determined by the EDTA volumetric method using chrome black T as an indicator. After deducting the CaO content, the MgO content is calculated.
11.2 Reagents
11.2.1 Ammonia water (density 0.90 g/cm2). 11.2.2 Hydrochloric acid: (1+1).
Sodium hydroxide solution (20%).
11.2.4 Hexamethylenetetramine solution (15%). 11.2.5 Methyl red indicator (0.1%). 11.2.6 Copper reagent.
Calcium reagent carboxylate sodium salt indicator: 1:100. 11.2.7
Weigh 0.5g of calcium reagent carboxylate sodium salt, grind it with 50g of sodium chloride and mix it evenly. 9
GB/T3045—-2003
11.2.8 Chrome black T indicator: 1:100.
Weigh 0.5g of Chrome black T, grind it with 50g of sodium chloride and mix it evenly. 11.2.9 Ammonium chloride-ammonia buffer solution: pH=10. Weigh 67.5g of ammonium chloride and dissolve it in 250mL of water, add 570mL of ammonia water (11.2.1), transfer it into a 1000mL volumetric flask, dilute it to the mark with water, and shake it evenly. bzxZ.net
11.2.10 EDTA standard solution
Weigh 3.75g of EDTA (disodium ethylenediaminetetraacetate) in a 400ml beaker, add 200mL of water, heat at low temperature to dissolve, filter in a 1000mL volumetric flask after cooling, dilute to scale with water, shake well, and this is the EDTA standard solution. Calibrate according to the following operations. Calibrate the titer of EDTA standard solution for CaO and MgO: weigh 1.7848g of calcium carbonate (reference reagent) dried at 110℃ for 2h in a 250ml beaker, add 50mL of water, add hydrochloric acid (1+1) until completely dissolved, and add 2~3 drops in excess, heat and boil to drive off carbon dioxide, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, shake well, and this is the calcium oxide standard solution (containing calcium oxide 1 mg/mL). Use a pipette to transfer 10mL of the above calcium oxide standard solution into a 300mL conical flask, add 80mL of water and 10mL of sodium hydroxide solution (11.2.3), shake well, add an appropriate amount of calcium reagent sodium carboxylate indicator, and titrate with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of the EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the value of the mass of calcium oxide, in grams (g); V——the value of the volume of the EDTA standard solution consumed in the titration, in milliliters (mL); Tcao——the value of the titer of the EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the value of the titer of the EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
... (10)
Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide solution (11.2.3), shake well, add a small amount of calcium indicator, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions. 11.3.3 Determination of magnesium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of ammonium chloride-ammonia buffer solution (11.2.9), add an appropriate amount of chrome black T indicator, shake well, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions.
11.4 Calculation of results
The mass content of calcium oxide (CaO), expressed in %, is calculated according to the following formula: w(CaO) - -- Vs X Tco
The mass content of magnesium oxide w(MgO), expressed in %, is calculated according to the following formula: 10
Wherein:
(V.-Va)× Tma × 100
w(MgO)=
m1—Numerical value of sample mass, in grams (g); Vi——Numerical value of the total volume of the filtrate prepared in 8.3, in milliliters (mL); V2—Numerical value of the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL); V—Numerical value of the total volume of the test solution prepared in 11.3.1, in milliliters (mL); GB/T3045—2003
（13）
-Numerical value of the volume of the test solution taken from 11.3.1 during determination in 11.3.2 or 11.3.3, in milliliters (mL); Vs
-Numerical value of the volume of EDTA standard solution consumed in titration in 11.3.2, in milliliters (mL); V. —--Numerical value of the volume of EDTA standard solution consumed in titration in 11.3.3, in milliliters (mL). The calculation result shall be accurate to 0.01.
Other analytical methods
X-ray fluorescence (RFA) or atomic absorption spectrometry (AAS) can also be used to determine calcium oxide and magnesium oxide.2) When it turns yellow, add hydrochloric acid (1+20) until the yellow disappears, add 5mL of hydrochloric acid (1+60), 2mL of ascorbic acid (10.2.4), 5mL of chrome azuro blue S (10.2.5), and 5mL of hexamethylenetetramine solution (10.2.6). Dilute with water to the scale, shake well, let stand for 15 minutes, use a 1cm colorimeter, and measure its absorbance at a wavelength of 550nm. Perform a blank test at the same time. After subtracting the blank test absorbance, check the mass of aluminum on the working curve. 10.4.2 Drawing of working curve
Use a pipette to transfer 2mL of hydrochloric acid solution (5+95) into 7 50mL volumetric flasks respectively, and then use a microburette to add 0.00mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, 5.00mL, and 6.00mL of aluminum standard solution (10.2.7) into the volumetric flasks respectively. Then, operate according to the method in 10.4.1, measure the absorbance, subtract the absorbance of the blank solution, and draw the working curve corresponding to the corresponding aluminum mass.
10.5 Calculation of results
The mass content of aluminum oxide w (Al2O), expressed in %, is calculated according to the following formula: w(Al2O3) = 1. 889 5 × -
Wherein:
ml--the value of the sample mass, in grams (g); -the value of the aluminum mass found on the working curve in the sample solution, in grams (g); m2
Vi--the value of the total volume of the filtrate prepared in 8.3, in milliliters (mL); Vz--the value of the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL). The calculation result is accurate to 0.01.
11 Determination of calcium oxide and magnesium oxide
11.1 Principle
·(9)
When the filtrate from which interfering elements such as iron and aluminum have been separated has a pH of 13, the CaO content is determined by the EDTA volumetric method using the calcium reagent sodium carboxylate as an indicator; when the pH is ~10, the total amount of CaO and MgO is determined by the EDTA volumetric method using chrome black T as an indicator. After deducting the CaO content, the MgO content is calculated.
11.2 Reagents
11.2.1 Ammonia water (density 0.90 g/cm2). 11.2.2 Hydrochloric acid: (1+1).
Sodium hydroxide solution (20%).
11.2.4 Hexamethylenetetramine solution (15%). 11.2.5 Methyl red indicator (0.1%). 11.2.6 Copper reagent.
Calcium reagent carboxylate sodium salt indicator: 1:100. 11.2.7
Weigh 0.5g of calcium reagent carboxylate sodium salt, grind it with 50g of sodium chloride and mix it evenly. 9
GB/T3045—-2003
11.2.8 Chrome black T indicator: 1:100.
Weigh 0.5g of Chrome black T, grind it with 50g of sodium chloride and mix it evenly. 11.2.9 Ammonium chloride-ammonia buffer solution: pH=10. Weigh 67.5g of ammonium chloride and dissolve it in 250mL of water, add 570mL of ammonia water (11.2.1), transfer it into a 1000mL volumetric flask, dilute it to the mark with water, and shake it evenly.
11.2.10 EDTA standard solution
Weigh 3.75g of EDTA (disodium ethylenediaminetetraacetate) in a 400ml beaker, add 200mL of water, heat at low temperature to dissolve, filter in a 1000mL volumetric flask after cooling, dilute to scale with water, shake well, and this is the EDTA standard solution. Calibrate according to the following operations. Calibrate the titer of EDTA standard solution for CaO and MgO: weigh 1.7848g of calcium carbonate (reference reagent) dried at 110℃ for 2h in a 250ml beaker, add 50mL of water, add hydrochloric acid (1+1) until completely dissolved, and add 2~3 drops in excess, heat and boil to drive off carbon dioxide, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, shake well, and this is the calcium oxide standard solution (containing calcium oxide 1 mg/mL). Use a pipette to transfer 10mL of the above calcium oxide standard solution into a 300mL conical flask, add 80mL of water and 10mL of sodium hydroxide solution (11.2.3), shake well, add an appropriate amount of calcium reagent sodium carboxylate indicator, and titrate with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of the EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the value of the mass of calcium oxide, in grams (g); V——the value of the volume of the EDTA standard solution consumed in the titration, in milliliters (mL); Tcao——the value of the titer of the EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the value of the titer of the EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
... (10)
Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide solution (11.2.3), shake well, add a small amount of calcium indicator, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions. 11.3.3 Determination of magnesium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of ammonium chloride-ammonia buffer solution (11.2.9), add an appropriate amount of chrome black T indicator, shake well, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions.
11.4 Calculation of results
The mass content of calcium oxide (CaO), expressed in %, is calculated according to the following formula: w(CaO) - -- Vs X Tco
The mass content of magnesium oxide w(MgO), expressed in %, is calculated according to the following formula: 10
Wherein:
(V.-Va)× Tma × 100
w(MgO)=
m1—Numerical value of sample mass, in grams (g); Vi——Numerical value of total volume of filtrate prepared in 8.3, in milliliters (mL); V2—Numerical value of volume of test solution taken from filtrate in 8.3, in milliliters (mL); V—Numerical value of total volume of test solution prepared in 11.3.1, in milliliters (mL); GB/T3045—2003
（13）
-Numerical value of volume of test solution taken from 11.3.1 during determination in 11.3.2 or 11.3.3, in milliliters (mL); Vs
-Numerical value of volume of EDTA standard solution consumed in titration in 11.3.2, in milliliters (mL); V. —--Numerical value of volume of EDTA standard solution consumed in titration in 11.3.3, in milliliters (mL). The calculation result shall be accurate to 0.01.
Other analytical methods
X-ray fluorescence (RFA) or atomic absorption spectrometry (AAS) can also be used to determine calcium oxide and magnesium oxide.2) When it turns yellow, add hydrochloric acid (1+20) until the yellow disappears, add 5mL of hydrochloric acid (1+60), 2mL of ascorbic acid (10.2.4), 5mL of chrome azuro blue S (10.2.5), and 5mL of hexamethylenetetramine solution (10.2.6). Dilute with water to the scale, shake well, let stand for 15 minutes, use a 1cm colorimeter, and measure its absorbance at a wavelength of 550nm. Perform a blank test at the same time. After subtracting the blank test absorbance, check the mass of aluminum on the working curve. 10.4.2 Drawing of working curve
Use a pipette to transfer 2mL of hydrochloric acid solution (5+95) into 7 50mL volumetric flasks respectively, and then use a microburette to add 0.00mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, 5.00mL, and 6.00mL of aluminum standard solution (10.2.7) into the volumetric flasks respectively. Then, operate according to the method in 10.4.1, measure the absorbance, subtract the absorbance of the blank solution, and draw the working curve corresponding to the corresponding aluminum mass.
10.5 Calculation of results
The mass content of aluminum oxide w (Al2O), expressed in %, is calculated according to the following formula: w(Al2O3) = 1. 889 5 × -
Wherein:
ml--the value of the sample mass, in grams (g); -the value of the aluminum mass found on the working curve in the sample solution, in grams (g); m2
Vi--the value of the total volume of the filtrate prepared in 8.3, in milliliters (mL); Vz--the value of the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL). The calculation result is accurate to 0.01.
11 Determination of calcium oxide and magnesium oxide
11.1 Principle
·(9)
When the filtrate from which interfering elements such as iron and aluminum have been separated has a pH of 13, the CaO content is determined by the EDTA volumetric method using the calcium reagent sodium carboxylate as an indicator; when the pH is ~10, the total amount of CaO and MgO is determined by the EDTA volumetric method using chrome black T as an indicator. After deducting the CaO content, the MgO content is calculated.
11.2 Reagents
11.2.1 Ammonia water (density 0.90 g/cm2). 11.2.2 Hydrochloric acid: (1+1).
Sodium hydroxide solution (20%).
11.2.4 Hexamethylenetetramine solution (15%). 11.2.5 Methyl red indicator (0.1%). 11.2.6 Copper reagent.
Calcium reagent carboxylate sodium salt indicator: 1:100. 11.2.7
Weigh 0.5g of calcium reagent carboxylate sodium salt, grind it with 50g of sodium chloride and mix it evenly. 9
GB/T3045—-2003
11.2.8 Chrome black T indicator: 1:100.
Weigh 0.5g of Chrome black T, grind it with 50g of sodium chloride and mix it evenly. 11.2.9 Ammonium chloride-ammonia buffer solution: pH=10. Weigh 67.5g of ammonium chloride and dissolve it in 250mL of water, add 570mL of ammonia water (11.2.1), transfer it into a 1000mL volumetric flask, dilute it to the mark with water, and shake it evenly.
11.2.10 EDTA standard solution
Weigh 3.75g of EDTA (disodium ethylenediaminetetraacetate) in a 400ml beaker, add 200mL of water, heat at low temperature to dissolve, filter in a 1000mL volumetric flask after cooling, dilute to scale with water, shake well, and this is the EDTA standard solution. Calibrate according to the following operations. Calibrate the titer of EDTA standard solution for CaO and MgO: weigh 1.7848g of calcium carbonate (reference reagent) dried at 110℃ for 2h in a 250ml beaker, add 50mL of water, add hydrochloric acid (1+1) until completely dissolved, and add 2~3 drops in excess, heat and boil to drive off carbon dioxide, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, shake well, and this is the calcium oxide standard solution (containing calcium oxide 1 mg/mL). Use a pipette to transfer 10mL of the above calcium oxide standard solution into a 300mL conical flask, add 80mL of water and 10mL of sodium hydroxide solution (11.2.3), shake well, add an appropriate amount of calcium reagent sodium carboxylate indicator, and titrate with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of the EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the value of the mass of calcium oxide, in grams (g); V——the value of the volume of the EDTA standard solution consumed in the titration, in milliliters (mL); Tcao——the value of the titer of the EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the value of the titer of the EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
... (10)
Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide solution (11.2.3), shake well, add a small amount of calcium indicator, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions. 11.3.3 Determination of magnesium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of ammonium chloride-ammonia buffer solution (11.2.9), add an appropriate amount of chrome black T indicator, shake well, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions.
11.4 Calculation of results
The mass content of calcium oxide (CaO), expressed in %, is calculated according to the following formula: w(CaO) - -- Vs X Tco
The mass content of magnesium oxide w(MgO), expressed in %, is calculated according to the following formula: 10
Wherein:
(V.-Va)× Tma × 100
w(MgO)=
m1—Numerical value of sample mass, in grams (g); Vi——Numerical value of total volume of filtrate prepared in 8.3, in milliliters (mL); V2—Numerical value of volume of test solution taken from filtrate in 8.3, in milliliters (mL); V—Numerical value of total volume of test solution prepared in 11.3.1, in milliliters (mL); GB/T3045—2003
（13）
-Numerical value of volume of test solution taken from 11.3.1 during determination in 11.3.2 or 11.3.3, in milliliters (mL); Vs
-Numerical value of volume of EDTA standard solution consumed in titration in 11.3.2, in milliliters (mL); V. —--Numerical value of volume of EDTA standard solution consumed in titration in 11.3.3, in milliliters (mL). The calculation result shall be accurate to 0.01.
Other analytical methods
X-ray fluorescence (RFA) or atomic absorption spectrometry (AAS) can also be used to determine calcium oxide and magnesium oxide.889 5 × -
Wherein:
ml--the value of the sample mass, in grams (g);-the value of the aluminum mass found on the working curve in the sample solution, in grams (g);m2
Vi--the value of the total volume of the filtrate prepared in 8.3, in milliliters (mL);Vz--the value of the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL). The calculation result is accurate to 0.01.
11 Determination of calcium oxide and magnesium oxide
11.1 Principle
·(9)
When the filtrate from which interfering elements such as iron and aluminum have been separated has a pH of 13, the CaO content is determined by the EDTA volumetric method using the calcium reagent sodium carboxylate as an indicator; when the pH is ~10, the total amount of CaO and MgO is determined by the EDTA volumetric method using chrome black T as an indicator. After deducting the CaO content, the MgO content is calculated.
11.2 Reagents
11.2.1 Ammonia water (density 0.90 g/cm2). 11.2.2 Hydrochloric acid: (1+1).
Sodium hydroxide solution (20%).
11.2.4 Hexamethylenetetramine solution (15%). 11.2.5 Methyl red indicator (0.1%). 11.2.6 Copper reagent.
Calcium reagent carboxylate sodium salt indicator: 1:100. 11.2.7
Weigh 0.5g of calcium reagent carboxylate sodium salt, grind it with 50g of sodium chloride and mix it evenly. 9
GB/T3045—-2003
11.2.8 Chrome black T indicator: 1:100.
Weigh 0.5g of Chrome black T, grind it with 50g of sodium chloride and mix it evenly. 11.2.9 Ammonium chloride-ammonia buffer solution: pH=10. Weigh 67.5g of ammonium chloride and dissolve it in 250mL of water, add 570mL of ammonia water (11.2.1), transfer it into a 1000mL volumetric flask, dilute it to the mark with water, and shake it evenly.
11.2.10 EDTA standard solution
Weigh 3.75g of EDTA (disodium ethylenediaminetetraacetate) in a 400ml beaker, add 200mL of water, heat at low temperature to dissolve, filter in a 1000mL volumetric flask after cooling, dilute to scale with water, shake well, and this is the EDTA standard solution. Calibrate according to the following operations. Calibrate the titer of EDTA standard solution for CaO and MgO: weigh 1.7848g of calcium carbonate (reference reagent) dried at 110℃ for 2h in a 250ml beaker, add 50mL of water, add hydrochloric acid (1+1) until completely dissolved, and add 2~3 drops in excess, heat and boil to drive off carbon dioxide, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, shake well, and this is the calcium oxide standard solution (containing calcium oxide 1 mg/mL). Use a pipette to transfer 10mL of the above calcium oxide standard solution into a 300mL conical flask, add 80mL of water and 10mL of sodium hydroxide solution (11.2.3), shake well, add an appropriate amount of calcium reagent sodium carboxylate indicator, and titrate with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of the EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the value of the mass of calcium oxide, in grams (g); V——the value of the volume of the EDTA standard solution consumed in the titration, in milliliters (mL); Tcao——the value of the titer of the EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the value of the titer of the EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
... (10)
Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide solution (11.2.3), shake well, add a small amount of calcium indicator, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions. 11.3.3 Determination of magnesium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of ammonium chloride-ammonia buffer solution (11.2.9), add an appropriate amount of chrome black T indicator, shake well, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions.
11.4 Calculation of results
The mass content of calcium oxide (CaO), expressed in %, is calculated according to the following formula: w(CaO) - -- Vs X Tco
The mass content of magnesium oxide w(MgO), expressed in %, is calculated according to the following formula: 10
Wherein:
(V.-Va)× Tma × 100
w(MgO)=
m1—Numerical value of sample mass, in grams (g); Vi——Numerical value of total volume of filtrate prepared in 8.3, in milliliters (mL); V2—Numerical value of volume of test solution taken from filtrate in 8.3, in milliliters (mL); V—Numerical value of total volume of test solution prepared in 11.3.1, in milliliters (mL); GB/T3045—2003
（13）
-Numerical value of volume of test solution taken from 11.3.1 during determination in 11.3.2 or 11.3.3, in milliliters (mL); Vs
-Numerical value of volume of EDTA standard solution consumed in titration in 11.3.2, in milliliters (mL); V. —--Numerical value of volume of EDTA standard solution consumed in titration in 11.3.3, in milliliters (mL). The calculation result shall be accurate to 0.01.
Other analytical methods
X-ray fluorescence (RFA) or atomic absorption spectrometry (AAS) can also be used to determine calcium oxide and magnesium oxide.889 5 × -
Wherein:
ml--the value of the sample mass, in grams (g);-the value of the aluminum mass found on the working curve in the sample solution, in grams (g);m2
Vi--the value of the total volume of the filtrate prepared in 8.3, in milliliters (mL);Vz--the value of the volume of the test solution taken from the filtrate in 8.3, in milliliters (mL). The calculation result is accurate to 0.01.
11 Determination of calcium oxide and magnesium oxide
11.1 Principle
·(9)
When the filtrate from which interfering elements such as iron and aluminum have been separated has a pH of 13, the CaO content is determined by the EDTA volumetric method using the calcium reagent sodium carboxylate as an indicator; when the pH is ~10, the total amount of CaO and MgO is determined by the EDTA volumetric method using chrome black T as an indicator. After deducting the CaO content, the MgO content is calculated.
11.2 Reagents
11.2.1 Ammonia water (density 0.90 g/cm2). 11.2.2 Hydrochloric acid: (1+1).
Sodium hydroxide solution (20%).
11.2.4 Hexamethylenetetramine solution (15%). 11.2.5 Methyl red indicator (0.1%). 11.2.6 Copper reagent.
Calcium reagent carboxylate sodium salt indicator: 1:100. 11.2.7
Weigh 0.5g of calcium reagent carboxylate sodium salt, grind it with 50g of sodium chloride and mix it evenly. 9
GB/T3045—-2003
11.2.8 Chrome black T indicator: 1:100.
Weigh 0.5g of Chrome black T, grind it with 50g of sodium chloride and mix it evenly. 11.2.9 Ammonium chloride-ammonia buffer solution: pH=10. Weigh 67.5g of ammonium chloride and dissolve it in 250mL of water, add 570mL of ammonia water (11.2.1), transfer it into a 1000mL volumetric flask, dilute it to the mark with water, and shake it evenly.
11.2.10 EDTA standard solution
Weigh 3.75g of EDTA (disodium ethylenediaminetetraacetate) in a 400ml beaker, add 200mL of water, heat at low temperature to dissolve, filter in a 1000mL volumetric flask after cooling, dilute to scale with water, shake well, and this is the EDTA standard solution. Calibrate according to the following operations. Calibrate the titer of EDTA standard solution for CaO and MgO: weigh 1.7848g of calcium carbonate (reference reagent) dried at 110℃ for 2h in a 250ml beaker, add 50mL of water, add hydrochloric acid (1+1) until completely dissolved, and add 2~3 drops in excess, heat and boil to drive off carbon dioxide, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, shake well, and this is the calcium oxide standard solution (containing calcium oxide 1 mg/mL). Use a pipette to transfer 10mL of the above calcium oxide standard solution into a 300mL conical flask, add 80mL of water and 10mL of sodium hydroxide solution (11.2.3), shake well, add an appropriate amount of calcium reagent sodium carboxylate indicator, and titrate with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of the EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the value of the mass of calcium oxide, in grams (g); V——the value of the volume of the EDTA standard solution consumed in the titration, in milliliters (mL); Tcao——the value of the titer of the EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the value of the titer of the EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
... (10)
Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide solution (11.2.3), shake well, add a small amount of calcium indicator, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions. 11.3.3 Determination of magnesium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of ammonium chloride-ammonia buffer solution (11.2.9), add an appropriate amount of chrome black T indicator, shake well, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions.
11.4 Calculation of results
The mass content of calcium oxide (CaO), expressed in %, is calculated according to the following formula: w(CaO) - -- Vs X Tco
The mass content of magnesium oxide w(MgO), expressed in %, is calculated according to the following formula: 10
Wherein:
(V.-Va)× Tma × 100
w(MgO)=
m1—Numerical value of sample mass, in grams (g); Vi——Numerical value of total volume of filtrate prepared in 8.3, in milliliters (mL); V2—Numerical value of volume of test solution taken from filtrate in 8.3, in milliliters (mL); V—Numerical value of total volume of test solution prepared in 11.3.1, in milliliters (mL); GB/T3045—2003
（13）
-Numerical value of volume of test solution taken from 11.3.1 during determination in 11.3.2 or 11.3.3, in milliliters (mL); Vs
-Numerical value of volume of EDTA standard solution consumed in titration in 11.3.2, in milliliters (mL); V. —--Numerical value of volume of EDTA standard solution consumed in titration in 11.3.3, in milliliters (mL). The calculation result shall be accurate to 0.01.
Other analytical methods
X-ray fluorescence (RFA) or atomic absorption spectrometry (AAS) can also be used to determine calcium oxide and magnesium oxide.7848g is placed in a 250ml beaker, 50ml of water is added, hydrochloric acid (1+1) is added dropwise until completely dissolved, and 2-3 drops are added in excess, heated to boil to drive off carbon dioxide, cooled, transferred to a 1000ml volumetric flask, diluted to scale with water, and shaken to obtain a calcium oxide standard solution (containing 1 mg/ml calcium oxide). 10ml of the above calcium oxide standard solution is transferred to a 300ml conical flask with a pipette, 80ml of water and 10ml of sodium hydroxide solution (11.2.3) are added, shaken well, and an appropriate amount of calcium reagent sodium carboxylate indicator is added, and titrated with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the mass of calcium oxide, in grams (g); V——the volume of EDTA standard solution consumed in titration, in milliliters (mL); Tcao——the titer of EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the titer of EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
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Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide solution (11.2.3), shake well, add a small amount of calcium indicator, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions. 11.3.3 Determination of magnesium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of ammonium chloride-ammonia buffer solution (11.2.9), add an appropriate amount of chrome black T indicator, shake well, and titrate with EDTA standard solution until pure blue is the end point. Perform a blank test under the same conditions.
11.4 Calculation of results
The mass content of calcium oxide (CaO), expressed in %, is calculated according to the following formula: w(CaO) - -- Vs X Tco
The mass content of magnesium oxide w(MgO), expressed in %, is calculated according to the following formula: 10
Wherein:
(V.-Va)× Tma × 100
w(MgO)=
m1—Numerical value of sample mass, in grams (g); Vi——Numerical value of total volume of filtrate prepared in 8.3, in milliliters (mL); V2—Numerical value of volume of test solution taken from filtrate in 8.3, in milliliters (mL); V—Numerical value of total volume of test solution prepared in 11.3.1, in milliliters (mL); GB/T3045—2003
（13）
-Numerical value of volume of test solution taken from 11.3.1 during determination in 11.3.2 or 11.3.3, in milliliters (mL); Vs
-Numerical value of volume of EDTA standard solution consumed in titration in 11.3.2, in milliliters (mL); V. —--Numerical value of volume of EDTA standard solution consumed in titration in 11.3.3, in milliliters (mL). The calculation result shall be accurate to 0.01.
Other analytical methods
X-ray fluorescence (RFA) or atomic absorption spectrometry (AAS) can also be used to determine calcium oxide and magnesium oxide.7848g is placed in a 250ml beaker, 50ml of water is added, hydrochloric acid (1+1) is added dropwise until completely dissolved, and 2-3 drops are added in excess, heated to boil to drive off carbon dioxide, cooled, transferred to a 1000ml volumetric flask, diluted to scale with water, and shaken to obtain a calcium oxide standard solution (containing 1 mg/ml calcium oxide). 10ml of the above calcium oxide standard solution is transferred to a 300ml conical flask with a pipette, 80ml of water and 10ml of sodium hydroxide solution (11.2.3) are added, shaken well, and an appropriate amount of calcium reagent sodium carboxylate indicator is added, and titrated with the prepared EDTA standard solution until pure blue is the end point.
Calculate the titer of EDTA standard solution for CaO and MgO according to the following formula: Teco
Tmgo Tcao X 0.718 8
Wherein:
m——the mass of calcium oxide, in grams (g); V——the volume of EDTA standard solution consumed in titration, in milliliters (mL); Tcao——the titer of EDTA standard solution for calcium oxide, in grams per milliliter (g/mL); TMgo——the titer of EDTA standard solution for magnesium oxide, in grams per milliliter (g/mL). 11.3 Analysis steps
11.3.1 Preparation of test solution
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Use a pipette to transfer 100 ml of the filtrate from 8.3 into a 250 ml volumetric flask. Add about 50 ml of water and 1 drop of methyl red indicator (11.2.5). Add ammonia water (11.2.1) until the solution turns yellow. Immediately add hydrochloric acid (1 + 1) until it turns red, and add two drops in excess. Add 5 ml of hexamethylenetetramine (11.2.4). Cool. Add about 0.1 g of copper reagent (11.2.6). Dilute to the mark with water. Shake well. Let stand for 1 hour. Dry filter into a dry beaker.
11.3.2 Determination of calcium oxide
Use a pipette to transfer 100mL of the test solution in 11.3.1 into a 300mL conical flask, add 10mL of sodium hydroxide soluti
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