GB/T 5195.5-1985 Chemical analysis method for fluorspar - Combustion-potassium iodate volumetric method for determination of total sulfur content GB/T5195.5-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of fluorspar
Determination of total sulfur content by the combustlon-patassium iodate volumetric methodMethods for chemical analysis of fluorsparThe combustlon-patassium iodate yolumetric methodfor the determination of total sulfar contentThis standard applies to the determination of total sulfur in fluorspar. Determination range: 0.003～0.500%. This standard complies with GB1467--78 "General Principles and General Provisions of Standards for Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
UDC 549.454
GB5195.5-85
The sample is burned in a nitrogen flow at 1200～1250℃, and the sulfur dioxide produced is absorbed by water to form sulfurous acid. Starch is used as an indicator and titrated with potassium iodate standard solution until the light blue color is the end point. 2 Reagents
2..1 Anhydrous sodium sulfate: high-grade pure or standard reagent. 2.2 Calcium fluoride.
2.3 Hydrochloric acid (1+1).
2.4 Starch solution (1%): Weigh 2g potato starch and 1g sodium chloride in a mortar, add a small amount of water and grind evenly, pour into about 150ml boiling water, boil, remove and cool. Add 30ml saturated boric acid solution, dilute to 200ml with water, stir and let stand. 2.5 Starch absorption solution (0.05%): Transfer 25.0ml of the clarified liquid of starch solution (2.4), add 400ml water and 15ml hydrochloric acid (2.3), dilute to 500ml with water, and mix well. 2.6 Potassium iodate standard storage solution (0.01N): Weigh 0.3567g potassium iodate (KI03), 1g potassium iodide and 2 potassium hydroxide, dissolve in water, transfer to a 1000ml volumetric flask, dilute to the scale with water, and mix well. 2.7 Potassium iodate standard solution (0.001N): Pipette 50.00ml potassium iodate standard stock solution (2.6) into a 500ml volumetric flask, add 1g potassium iodide, dilute to scale with water, and mix. Prepare 0.002N potassium iodate standard solution in the same way as above. Calibration: Weigh three portions of a standard sample (2.8) with a sulfur content similar to that of the sample, place in a porcelain boat, and measure according to 5.3.6 to 5.3.8. Perform a blank test of two portions of calcium fluoride (used to prepare the standard sample). Calculate the sulfur titer of potassium iodate standard solution according to formula (1): TwwW.bzxz.Net
the sulfur titer of potassium iodate standard solution, g/ml; the percentage content of the standard sample;
the amount of the standard sample weighed, g,
the average volume of potassium iodate standard solution consumed by the standard sample (if the extreme difference value exceeds 0.20ml, it should be re-standardized
), ml;
the average volume of potassium iodate standard solution consumed in the blank test, ml. 2.8 Preparation of standard sample
National Bureau of Standards 1985-05-18 Issued
1986-03-01 Implementation
GB5195.5-85
2.8.1 Dry anhydrous sodium sulfate (2.1) and calcium fluoride (2.2) at 105±1℃ for 2h, and cool to room temperature in a flat desiccator: 2.8.2 Weigh 0.2215g of anhydrous sodium sulfate (2.1) and 4.7785g of calcium fluoride (2.2), place in an agate mortar:, and grind carefully. The theoretical sulfur content of the standard sample is 1%.
2.8.3 Weigh 0.5000g of the standard sample (2.8.2) that has been dried at 105±1℃ for 2h and placed in a desiccator to cool to room temperature, and 4.5000g of calcium fluoride (2.2), place them in an agate mortar, and grind them carefully. The theoretical sulfur content of the standard sample is 0.10%. According to the preparation method in 3.8.3, prepare standard samples with theoretical sulfur contents of 0.05%, 0.02%, and 0.005% respectively. The prepared standard samples must ensure their uniformity. 3 Instruments
Sulfur measurement device using the potassium iodate combustion method (see Figure 1). Figure 1
1-Nitrogen bottle, 2-gas buffer bottle; 3-gas washing bottle; 4-drying tower, 5-glass piston; 6--tube electric furnace, 7-single bulb: 8-porcelain tube; 9-porcelain boat; 10-sulfur oxide absorption cup and reference solution cup; 11-burette
3.1 Nitrogen bottle, equipped with oxygen flow meter.
3.2 Gas buffer bottle.
3.3 Gas washing bottle, containing 100-150ml sulfuric acid (specific gravity 1.84). 3.4 Drying tower, with potassium hydroxide at the bottom, glass wool in the middle, and anhydrous calcium chloride at the top. 3.5 Glass piston.
3.6 Tubular electric furnace, maximum temperature 1350℃. 3.7 Single bulb, with a small amount of dry absorbent cotton or glass wool. 3.8 Porcelain tube (unglazed, outer diameter 25mm, inner diameter 20mm, length 600mm), all parts are staggered and burned for 1min under the test conditions before use.
3.9 Porcelain boat (unglazed, 77mm or 88mm), burned under the test conditions until the absorption liquid keeps a light color for 1min without fading. : Put it in the desiccator for use.
3.10 Sulfur dioxide absorption cup and reference solution cup (see Figure 2). 158
3.1125ml or 10ml burette.
4 Sample
4.1 The sample should pass through a 240 mesh screen.
GB5195.5—85
4.2 The sample is dried at 105±1℃ for 2h in advance and cooled to room temperature in a desiccator. 5 Analysis steps
5.1 Determination quantity
Three samples should be weighed for determination and the average value should be taken. 5.2 Sample quantity
Weigh the sample according to Table 1.
>0.050~0.150
0.150～0.300
0.300 ~ 0.500
5.3 Determination
Sample quantity
Concentration of potassium iodate standard solution
5.3.1 Connect the sulfur measuring device according to Figure 1. Turn on the power supply and gradually increase the furnace temperature to 1200～1250℃. 5.3.2 Introduce nitrogen into the sulfur measuring device and check that the device is leak-proof before determination. 5.3.3 Add 60ml starch solution (2.5) to the sulfur oxide absorption cup. Pass nitrogen at a flow rate of 100-200 ml/min. Select potassium iodate standard solution according to Table 1, titrate until light blue (same color as reference solution), and turn off nitrogen. Preparation of reference solution: Add 60 ml starch solution (2.5) to the reference tube, and titrate with potassium iodate standard solution (2.7) until light blue.
5.3.4 Pre-burn 1-2 samples according to 5.3.5-5.3.8 to balance the measurement conditions. GB 5195.5-85
5.3.5 Spread half of the sample (5.2) in a porcelain boat (3.9) and place it in a desiccator for measurement. 5.3.6 Adjust the nitrogen flow rate to about 150ml/min (the gas flow rate control is consistent for the same batch of operations) 5.3.7 Use a nickel-chromium alloy hook to quickly push the porcelain boat into the high temperature zone of the tube furnace, immediately plug the tube mouth with a rubber plug, and pass nitrogen at a flow rate of about 150ml/min to allow the "sulfur oxide gas to be absorbed by the absorption liquid. 5.3.8 When the light blue color of the absorption liquid is reduced and faded, Lilang titrates with potassium iodate standard solution (2.7) until the light blue color of the solution is consistent with the color of the reference solution and remains unchanged for 1 minute as the end point. 6 Calculation of analysis results
Calculate the percentage of sulfur according to formula (2):
X 100 :
Formula: T——-titration degree of potassium iodate standard solution on sulfur, g/ml; V-average volume of potassium iodate standard solution consumed by the sample, ml; sample volume, g.
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
Additional notes:
0.003~0.010
>0.010 ~ 0.020
0.020 ~ 0. 050
0. 050 ~ 0. 100
0.100 ~0.200
>0.200 ~ 0.500
This standard was proposed by Shanrun Nonferrous Metals Corporation. Zhejiang Fluorite Mining Company was responsible for drafting this standard. This standard was drafted by Zhejiang Metallurgical Research Institute. Jiang Shaojuan was the main drafter of this standard.
From the date of implementation of this standard, the former Ministry of Metallurgy and Industry Standard YB322-65 "Chemical Analysis Method of Fluorite" will be invalid. 160
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