GB/T 15057.8-1994 Determination of sulfur content in limestone for chemical industry - Barium sulfate gravimetric method and combustion-potassium iodate titration method
Some standard content:
National Standard of the People's Republic of China
Determination of sulfur content in limestone for chemical industry
Barium sulfate gravimetric method and combustion-iodate titrimetric method Limestone for chemical industry-Determination of sulfur content-Gravimetricand combustion-iodate titrimetric methods Part I Gravimetric method
Subject content and scope of application
This standard specifies the determination of sulfur content by barium sulfate gravimetric method. GB/T15057.8-94
This standard applies to the determination of sulfur content in limestone products for chemical industry, with a determination range of more than 0.05%. 2 Reference standards
GB6682 Specifications and test methods for water for analytical laboratories 3 Summary of methods
The sample is decomposed with nitric acid and potassium chlorate to oxidize sulfur into sulfate, and hydrochloric acid is added to evaporate to remove nitric acid. The solution is filtered to remove insoluble matter such as silicon, and barium fluoride is added to a hydrochloric acid medium with a pH of 1 to form a barium sulfate precipitate. Filter, burn the precipitate, and weigh it. The sulfur content is calculated from the mass of barium sulfate.
Reagents and solutions
The water used in this standard shall comply with the specifications of Grade III water in GB6682; the listed reagents, unless otherwise specified, are analytically pure reagents. 4.1
Potassium chlorate (GB645).
Nitric acid (GB626): 1+1 solution.
Hydrochloric acid (GB622).
Hydrochloric acid: 1+1 solution.
Hydrochloric acid: 1+100 solution.
Hydroxylamine hydrochloride (GB6685): 50g/L solution. 4.6
Barium chloride (BaCl, ·2H,O) (GB652): 100g/L solution. Weigh 100g of barium chloride and dissolve it in an appropriate amount of water. After filtering, dilute it to 1000mL with water.
4.8Silver nitrate (GB670): 10g/L solution. 5 Sample
Laboratory sample passed through 125μm test sieve (GB6003), dried at 105~110℃ for more than 2h, placed in a desiccator and cooled to room temperature. bzxZ.net
Approved by the State Administration of Technical Supervision on May 5, 1994
Implementation on February 1, 1995
6 Analysis steps
GB/ 15057.8—94
6.1 Weigh about 5g of sample, accurate to 0.0018, and place in a 200mL beaker. Perform a blank test at the same time. 6.2 Add about 1g of potassium cyanate (4.1), moisten with a little water and shake it up. Add 20mL of nitric acid solution (4.2) slowly along the mouth of the beaker. After the violent reaction stops, rinse the surface and the wall of the beaker with water. 6.3 Cover the surface and remove part, heat on a low-temperature electric hot plate, and evaporate to dryness. Cool, rinse the surface with a little water. Slowly add 8mL hydrochloric acid (4.3) around the beaker and evaporate to dryness. Cool, add another 8mL hydrochloric acid (4.3) and evaporate to dryness. 6.4 Add 4.0mL hydrochloric acid solution (4.4), add water to 30ml, and heat to a slight boil. Heat the solution with medium-speed filter paper into a 400mL beaker, wash the beaker with water, and wash the precipitate 8-10 times. 6.5 Add 5-10mL hydroxylamine hydrochloride solution (4.6), stir, heat, and fade the yellow color. Dilute to 250mL with hot water, heat to a slight boil, and add 10mL hot fluoride lock solution (4.7) dropwise while stirring continuously. Cover with surface 1, keep warm at 80-95℃ for about 2h, and let stand overnight at room temperature.
6.6 Filter with slow quantitative filter paper, transfer the precipitate to the filter paper, wash with hydrochloric acid solution (4.5) 3~4 times, then wash the precipitate with warm water until the filtrate is free of fluoride ions, and test with silver nitrate solution (4.8). 6.7 Put the precipitate and filter paper into a constant amount of platinum or porcelain, dry, ash, and place in a high-temperature furnace to burn at 800℃ for 30min. Take out the crucible, put it in a desiccator, cool to room temperature, and weigh. Repeat the burning until constant weight. 7 Expression of analysis results
The (S) content (z) expressed as mass percentage is calculated according to formula (1): [(m -m2) (m: m)]X0.1374×100+oo*#**+*（1）
Wherein:
=mass of barium sulfate precipitate and crucible,
mass of the blank test precipitate and crucible,
mass of the blank test precipitate and crucible,
m —mass of the sample
0.1374-factor for converting barium sulfate to sulfur. 8 Allowable difference
The arithmetic mean of the parallel analysis results is taken as the final analysis result. The absolute difference between the parallel analysis results should not be greater than the allowable difference listed in Table 1.
Sulfur (S) content
0.0300.050
>0. 050~0. 120
>0.120~0.300
Yunzhu Chuanshe
Foreign standard industry information free hall
Allowance difference
9 Subject content and scope of application
GB/T 15057.8—94
Part 2 Combustion-iodate titration method
This standard specifies the determination of sulfur content by combustion-iodate titration method. This standard is applicable to the determination of sulfur content in limestone products for chemical industry, and the determination range is greater than 0.01%. 10 Reference Standards
GB6682 Specifications and Test Methods for Water Used in Analytical Laboratories 11 Summary of Methods
The sample is mixed with tungsten trioxide and burned at 1250-1300℃ in a nitrogen stream to convert all sulfur into sulfur dioxide, which is absorbed by a dilute hydrochloric acid solution containing potassium iodide starch and titrated with a potassium iodate standard titration solution. 12 Reagents and Solutions
The water used in this standard shall comply with the specifications of Grade III water in GB6682; the listed reagents, unless otherwise specified, are analytically pure reagents. 12.1 Powdered tungsten trioxide: Dry at 110℃ for 2h and place in a desiccator for use. 12.2 Hydrochloric acid (GB622): 1.5+98.5 hydrochloric acid absorption solution. 12.3 Potassium iodide (GB1272): 30g/L solution, stored in a brown bottle. -KI0g) = 0.003120mol/L. Weigh 0.1113g of potassium iodate (GB1258) that has been dried at 105-110℃ for 2h in advance. 12.4 Potassium iodate standard titration solution: c(
and placed in a desiccator to cool to room temperature, dissolve in water, transfer to a 1000mL volumetric flask, dilute to scale with water, and shake well. 1mL of this solution is equivalent to 0.00005g of sulfur. 12.5 Starch: 20g/L solution. Weigh 2g of soluble starch and place in a 200mL beaker, add a little water to mix thoroughly, add about 50mL of boiling water, stir constantly, boil on an electric stove for about 1min, remove, cool, and dilute with water. To 100mL, shake well, and let stand. Take the upper clear liquid when using. Note: The starch quality should be good, and the end point color should be pure blue. If the starch turns red during titration, it should be discarded and re-prepared. 13 Instrumentation
The sulfur content determination device is shown in Figure 1.
13.1 Steel cylinder (1): Nitrogen purity greater than 99.5%. 13.2 Gas flowmeter (2): 0~15L/min. 13.3 Buffer bottle (3).
13.4 Washing bottle (4): Contains chromic acid and saturated sulfuric acid. Add potassium dichromate (GB642) to sulfuric acid (GB625) to saturate it, and take The upper clear liquid is loaded into the gas washing bottle, and the loading amount is about one-third of the bottle height. 13.5 Drying tower (5): Contains caustic soda asbestos, and a layer of glass wool is laid on the top and bottom. 13.6 Gas washing bottle (6): Contains sulfuric acid (GB625), and the loading amount is about one-third of the bottle height. 13.7 Drying tower (7): Contains anhydrous magnesium perfluoride or anhydrous calcium chloride (HGB3208), and a layer of glass wool is laid on the top and bottom. 13.8 Tubular combustion furnace (8): Maximum operating temperature 1350℃. 13.9 Automatic temperature controller (9).
13.10 Porcelain boat (10): Length 95~1 00mm, inner width 9~13mm, height 10~12mm (the size should be matched with the porcelain tube). Unglazed, high temperature resistant. Clean and dry before use, burn in a high temperature furnace at 1000℃ for more than 1h, and place in a dryer for standby after cooling. 13.71 Porcelain tube (11): inner diameter 18~22mm, length 600mm, one end is tapered. Unglazed, high temperature resistant. Before using a new porcelain tube, all parts must be burned under measuring conditions for 10min.
13.12 Burette (12): 25mL or 10mL. GB/T 1 5057. 894
13.13 Reagent bottle (13): Contains potassium iodate standard titration solution. 13.14 Absorption bottle (14): Used to absorb sulfur dioxide, as shown in Figure 2. 13.15 Colorimetric bottle (15).
13.16 Fluorescent lamps (16).
Figure 1 Sulfur content determination device diagram
1-Nitrogen cylinder; 2-Gas flowmeter, 3-Buffer bottle: 4-Washing bottle: 5-Drying tower: 6--Washing bottle; 7-Drying tower; 8-Tube combustion furnace; 9-Temperature automatic controller; 10-Ceramic boat: 11-Ceramic tube; 12-Burette 13-Reagent bottle; 14-Absorption bottle; 15-Colourimetric bottle; 16-Fluorescent lamp connected to burette
Fine-pore porcelain sand sheet
Figure 2 Absorption bottle
Quasi-made
Slow-absorbing liquid injection port
Applied liquid discharge port
14 Test sample
GB/T15057.8-94
Laboratory sample passed through 125um test sieve (GB6003), dried at 105-110℃ for more than 2h, and placed in a desiccator to cool to room temperature.
15 Analysis steps
15.1 Determination
15.1.1 Connect the determination device according to Figure 1, and gradually heat the combustion furnace to 1250℃. Check that the device should be tight and leak-proof when passing nitrogen. 15.1.2 Pre-burn 1 to 2 samples according to the following determination steps to balance the determination conditions. 15.1.3 Weigh about 0.5g of the sample (when the sulfur content is greater than 0.2%, weigh about 0.25g), accurate to 0.0001g. Perform a blank test at the same time. 15.1.4 Place the sample in a porcelain boat pre-filled with 1.5g of tungsten trioxide (12.1), stir it evenly with a fine metal wire and spread it flat (be careful not to spill it). If necessary, cover it with about 0.5g of tungsten trioxide (12.1). 15.1.5 Take 60mL of hydrochloric acid absorption solution (12.2), add 1mL of potassium iodide solution (12.3) and 1mL of powder solution (12.5), add potassium iodate standard titration solution (12.4) dropwise until the solution turns light blue, and inject it into the sulfur dioxide absorption bottle (13.14). Take another portion in the same way and inject it into the colorimetric bottle. Pass gas into the absorption bottle and adjust the flow rate to about 150-200mL/min. Titrate the absorption solution with potassium iodate standard titration solution (12.4) to turn it light blue and consistent with the color of the solution in the colorimetric bottle. Then adjust the solution in the burette to zero. Depending on the sulfur content of the sample, pre-add about 1mL of potassium iodate standard titration solution (12.4). 15.1.6 Remove the rubber stopper at one end of the porcelain tube inlet, use a nickel-chromium wire hook to send the porcelain boat containing the sample into the high temperature of the porcelain tube, immediately plug the rubber stopper, and allow nitrogen flow to pass through the combustion furnace. The mixed gas after combustion is introduced into the sulfur dioxide absorption bottle. The blue color of the starch absorption liquid at the bottom of the bottle begins to fade. Immediately titrate with potassium iodate standard titration solution (12.4). Pass nitrogen for 5 to 6 minutes. When the absorption liquid fades slowly, the titration speed is slowed down until the light blue color of the absorption liquid is consistent with the color of the solution in the colorimetric bottle and remains unchanged for 1 minute. Record the volume of potassium iodate standard titration solution consumed.
15.1.7 Remove the imported rubber stopper, pull out the porcelain boat, and measure the next sample. Note: ① It is best to replace the potassium iodide-starch acid absorption liquid after one use: for samples with a sulfur content of less than 0.1%, it can be continuously measured for 2~~~~3 samples before replacing.
② Observe the combustion of the sample in the porcelain boat. If the slag is uneven and there are bubbles on the cross section, it needs to be re-measured. If it is still the case, the furnace temperature can be slightly increased or the amount of tungsten trioxide can be increased.
15.2 Calibration test
Weigh two portions of limestone standard material with a sulfur content similar to that of the sample, and conduct routine calibration tests on this method according to 15.1. The correction factor (f) is calculated according to formula (2):
f=(V--V)×0. 000 05
Wherein: B——mass percentage of sulfur in the standard material; volume of potassium iodate standard titration solution, mLV
V. Blank test volume of potassium iodate standard titration solution, mL; m
mass of the standard material, gt
(2)
——grams of sulfur equivalent to each milliliter of potassium iodate standard titration solution, g/mL. 0.00005
The difference in the volume of potassium iodate standard titration solution consumed in the two portions shall not exceed 0.20mL. Take the arithmetic mean of the two determinations as the correction factor of this method. The correction factor should be greater than 1. 16 Expression of analysis results
The sulfur (S) content (z) expressed as mass percentage is calculated according to formula (3): (V--V.)f x0. 000 05
Normal batch extraction
（3）
Where: f
Correction factor
GB/T 15057.8-94
Volume of potassium iodate standard titration solution, mL, Blank test volume of potassium iodate standard titration solution, mL; Mass of sample, g:
—Number of grams of sulfur equivalent to each milliliter of potassium iodate standard titration solution, g/mL. 0. 000 05-
17 Allowable difference
Take the arithmetic mean of the parallel analysis results as the final analysis result. The absolute difference of the parallel analysis results should not be greater than the allowable difference listed in Table 2.
Additional Notes:
Sulfur (S) content
>0.010~0.050
>0.050~0.120
>0.120~～0.300
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. Table 2
Allowable difference
This standard was drafted by the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Wang Heping and Li Donghao. This standard refers to the Japanese Industrial Standard JISM8850-1982 "Limestone Analysis Method". 208
Standard Search Change Network.For 1% samples, 2~~~3 samples can be measured continuously before replacement.
②Observe the combustion of the sample in the porcelain boat. If the slag is uneven and there are bubbles on the cross section, re-measurement is required. If it is still the case, the furnace temperature can be slightly increased or the amount of tungsten trioxide can be increased.
15.2 Calibration test
Weigh two portions of limestone standard material with a sulfur content similar to that of the sample, and perform daily calibration tests on this method according to Article 15.1. The correction factor (f) is calculated according to formula (2):
f=(V--V)×0. 000 05
Where: B——mass percentage of sulfur in the standard material; volume of potassium iodate standard titration solution, mLV
V. Blank test volume of potassium iodate standard titration solution, mL; m
Mass of standard substance, gt
(2)
Number of grams of sulfur equivalent to each milliliter of potassium iodate standard titration solution, g/mL. 0.00005
The difference in the volume of potassium iodate standard titration solution consumed in the two portions shall not exceed 0.20mL. The arithmetic mean of the two determinations shall be taken as the correction factor of this method. The correction factor should be greater than 1. 16 Expression of analysis results
The sulfur (S) content (z) expressed as mass percentage is calculated according to formula (3): (V--V.)f x0. 000 05
Normal batch extraction
（3）
Where: f
Correction factor
GB/T 15057.8-94
Volume of potassium iodate standard titration solution, mL, Blank test volume of potassium iodate standard titration solution, mL; Mass of sample, g:
—Number of grams of sulfur equivalent to each milliliter of potassium iodate standard titration solution, g/mL. 0. 000 05-
17 Allowable difference
Take the arithmetic mean of the parallel analysis results as the final analysis result. The absolute difference of the parallel analysis results should not be greater than the allowable difference listed in Table 2.
Additional Notes:
Sulfur (S) content
>0.010~0.050
>0.050~0.120
>0.120~～0.300
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. Table 2
Allowable difference
This standard was drafted by the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Wang Heping and Li Donghao. This standard refers to the Japanese Industrial Standard JISM8850-1982 "Limestone Analysis Method". 208
Standard Search Change Network.For 1% samples, 2~~~3 samples can be measured continuously before replacement.
②Observe the combustion of the sample in the porcelain boat. If the slag is uneven and there are bubbles on the cross section, re-measurement is required. If it is still the case, the furnace temperature can be slightly increased or the amount of tungsten trioxide can be increased.
15.2 Calibration test
Weigh two portions of limestone standard material with a sulfur content similar to that of the sample, and perform daily calibration tests on this method according to Article 15.1. The correction factor (f) is calculated according to formula (2):
f=(V--V)×0. 000 05
Where: B——mass percentage of sulfur in the standard material; volume of potassium iodate standard titration solution, mLV
V. Blank test volume of potassium iodate standard titration solution, mL; m
mass of standard substance, gt
(2)
one milliliter of potassium iodate standard titration solution is equivalent to the number of grams of sulfur, g/mL. 0.00005
The difference in the volume of potassium iodate standard titration solution consumed by the two parts shall not exceed 0.20mL. The arithmetic mean of the two determinations shall be taken as the correction factor of this method. The correction factor should be greater than 1. 16 Expression of analysis results
The sulfur (S) content (z) expressed as mass percentage is calculated according to formula (3): (V--V.)f x0. 000 05
Normal batch extraction
（3）
Where: f
Correction factor
GB/T 15057.8-94
Volume of potassium iodate standard titration solution, mL, Blank test volume of potassium iodate standard titration solution, mL; Mass of sample, g:
—Number of grams of sulfur equivalent to each milliliter of potassium iodate standard titration solution, g/mL. 0. 000 05-
17 Allowable difference
Take the arithmetic mean of the parallel analysis results as the final analysis result. The absolute difference of the parallel analysis results should not be greater than the allowable difference listed in Table 2.
Additional Notes:
Sulfur (S) content
>0.010~0.050
>0.050~0.120
>0.120~～0.300
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. Table 2
Allowable difference
This standard was drafted by the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Wang Heping and Li Donghao. This standard refers to the Japanese Industrial Standard JISM8850-1982 "Limestone Analysis Method". 208
Standard Search Change Network.
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