GB/T 15057.7-1994 Determination of alumina content in limestone for chemical industry - Chrome azurol S spectrophotometric method

This standard specifies the chrome azuro blue S spectrophotometric method for the determination of alumina content. This standard is applicable to the determination of alumina content in limestone products for chemical use, with a determination range of 0.01% to 1%. GB/T 15057.7-1994 Determination of alumina content in limestone for chemical use Chrome azuro blue S spectrophotometric method GB/T15057.7-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of aluminium oxide content in limestone for chemical industry-Chromazurol S spectrophotometric method
Limestone for chemical industry-Determination of aluminium oxide content-Chromazurol S spectrophotometric method1 Subject content and scope of application
This standard specifies the determination of aluminium oxide content by chromium sulfide S spectrophotometric method. GB/T 15057.7-94
This standard applies to the determination of aluminium oxide content in limestone products for chemical industry, with a determination range of 0.01% to 1%. 2 Reference standards
GB 6682 Specifications and test methods for water for analytical laboratoriesGB/T9721 General rules for molecular absorption spectrophotometry of chemical reagents (ultraviolet and visible light part) 3 Summary of the method
The sample is melted with sodium carbonate-boric acid mixed flux and leached with hydrochloric acid. Ascorbic acid is used to mask iron, phenylglycolic acid is used to mask titanium, and in the acetic acid-sodium acetate buffer system, aluminum reacts with chrome azuro S and the surfactant vinyl alcohol to form a purple-red ternary complex, and the absorbance is measured at a wavelength of 560nm on a spectrophotometer.
4 Reagents and solutions
The water used in this standard should meet the specifications of grade 3 water in GB6682; the listed reagents, unless otherwise specified, are analytically pure reagents. 4.1 Mixed flux: grind 2 parts of anhydrous sodium carbonate (GB639) and 1 part of boric acid (GB628) and mix them. 4.2 Sodium hydroxide (GB629): 200g/L solution. Store in a plastic bottle. 4.3 Sodium hydroxide: 50g/L solution. Store in a plastic bottle. 4.4 Hydrochloric acid (GB622): 1+1 solution.
4.5 Hydrochloric acid: 1+6 solution.
4.6 Ascorbic acid: 10g/L solution (prepare before use). 4.7 Phenylhydroxyacetic acid: 10g/L solution.
4.8 Chrome azuro blue S: 1g/L solution. Weigh 0.5g Chrome azuro blue S and dissolve it in 250mL ethanol (GB679), dilute to 500mL with water. 4.9 Polyvinyl alcohol: 20g/L solution. Weigh 4g mulberry vinyl alcohol, add 10mL methanol (GB683), 150mL water, heat to boiling, filter, cool, dilute to 200mL with water.
4.10 Acetic acid-sodium acetate buffer solution: Weigh 200g anhydrous sodium acetate (GB694) and dissolve it in 500mL water, add 20mL glacial acetic acid (GB676), dilute to 1000mL with water. 4.11 Alumina standard solution: 200μg/mL. Weigh 0.1058g-metal aluminum (high-purity reagent) and place it in a polytetrafluoroethylene plastic beaker, add 10mL sodium hydroxide solution (4.2), heat at low temperature to dissolve, and cool. Add hydrochloric acid solution (4.4) dropwise until the precipitate dissolves, then add 20mL in excess, and cool. State Bureau of Technical Supervision 1994-05-05 Approved 200
1995-02-01 Implementation
GB/T15057.7-94
The solution is transferred to a 1000mL volumetric flask, diluted with water to the mark, and shaken. This solution contains 200μg aluminum oxide in 1mL. 4.12 Alumina standard solution: 5ug/mL. Pipette 25.00ml aluminum oxide standard solution (4.11) and place it in a 1000ml volumetric flask, add 20mL hydrochloric acid solution (4.4), dilute with water to the mark, and shaken. This solution contains 5μg aluminum oxide in 1mL. 4.13 Thymol blue indicator (HG3--1223): 2 bags/1 ethanol (GB679) solution. 5 Instruments
Spectrophotometer: It should comply with the provisions of GB9721. 6 Samples
Laboratory samples should pass through a 125m test sieve (GB6003), dry at 105~110C for more than 2h, place in a hand dryer, and cool to room temperature.
7 Analysis steps
7.1 Weigh the sample according to the provisions of Table 1, accurate to 0.0001g, and place it in platinum clamps. At the same time, perform a blank test. Note: When measuring samples with an aluminum oxide content of less than 0.1%, two blanks should be made for drawing the working curve. Table 1
Meaning of aluminum oxide, %
0. 010~0. 050
>0. 05-0. 10
>0.10~0.50
>0.50~1.00
Weigh the sample element
Sample liquid volume, U.S.
Adsorption test volume, mL
7.2Add 2~3g mixed flux (4.1) and mix well, then cover with 1g mixed flux, blue on blue and leave a gap, place in a high temperature furnace, raise from low temperature to 950℃, keep for 10min, take out, cool. Put the plate in a 250mL beaker, add 40ml hot water and 15mL hydrochloric acid solution (4.4), heat at low temperature to dissolve the melt, wash the exhaust and cover with water. Continue heating until the solution is clear, cool to room temperature, transfer to a 100mL volumetric flask, dilute to scale with water, and shake well. The blank solution here is A. 7.3 According to the content of aluminum oxide in the sample, a certain volume of test solution is drawn into a 100mL volumetric flask as specified in Table 1, and add water to 40ml
7.4 Add 1.0ml. ascorbic acid solution (46), 2 drops of thymol blue indicator solution (4.13), and add sodium hydroxide solution (4.2) until the solution turns light red, then carefully add sodium hydroxide solution (4.3) until it turns bright yellow, add 2 drops of hydrochloric acid solution (4.5), and shake well. 7.5 Add 1.0 mL of benzoyl acetate solution (4.7), add 5.0 mL of chromium sulfoxide solution (48) and 10.0 mL of polyvinyl alcohol solution (4.9) along the wall of the volumetric flask, let stand for 5 minutes, add 10.0 mL of acetic acid-sodium acetate buffer solution (4.10) (shake gently after adding each reagent). Let stand for 10 minutes, dilute to the scale with water, and shake well. Note: For samples without titanium, benzoyl acetate solution may not be added. 7.6 Select a 1 cm absorption cell, and measure the absorbance at a wavelength of 560 nm in the spectrophotometer, using the blank test solution as a reference. 8 Drawing of working curve
Measure 0.00, 1.00, 2.00, 4.00, 6.00, 8.00, 10.00mL of aluminum oxide standard bath solution (4.12) and place them in 100mL volumetric flasks respectively. Add blank solution A with a volume between that of the test solution and that of the test solution, and add water to 40mL. Follow the steps in 7.4 to 7.6, in which the reagent blank is used as a reference and the absorbance is measured. Draw the working curve with the amount of aluminum oxide as the horizontal coordinate and the corresponding absorbance as the vertical coordinate. 9 Description of analysis results
The content of aluminum oxide (Al2O) expressed as mass percentage (%) is calculated as follows: 201 Www.bzxZ.net
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GB/T 1 5057. 7 - 94
m×10-6
Where: m-amount of aluminum oxide obtained from the working curve,; V, volume of sample solution absorbed, mL;
V-total volume of sample solution, mL,
m-mass of sample, g.
10 Allowable difference
Take the arithmetic mean of the parallel analysis results as the final result, and the absolute difference of the parallel analysis results should not be greater than the allowable difference listed in Table 2. %
Alumina (AIO) content
0. 010~0.050
>0.05~0.15
>0.15~0.50
>0.50~1.00
Additional notes:
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. This standard is drafted by the Chemical Industry Mining Design and Research Institute of the Ministry of Chemical Industry. Allowable difference
The main drafters of this standard are Wang Yangwen and Li Donghao. This standard refers to the German standard DIN52240-4--1985 "Inspection of raw materials for glass products Chemical analysis of limestone with a minimum calcium carbonate content of 95% Determination of aluminum oxide content". 202
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