GB/T 4324.23-1984 Chemical analysis of tungsten - Combustion-conductivity method for determination of sulfur content

GB/T 4324.23-1984 Chemical analysis of tungsten - Combustion-conductivity method for determination of sulfur content GB/T4324.23-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of tungsten
Determination of sulfur content by combustion-conductometric titration method
Methodsfor chemical analysis of tungstenThe conbustion-conductometric titration methodfor the determination of suphur contentUDC 669.27:543
.273 : 546.22
GB 4324.23—84
This standard is applicable to the determination of sulfur content in tungsten powder, tungsten strips, tungsten trioxide, tungsten acid and ammonium paratungstate. Determination range: 0.0005～0.012%. This standard complies with GB1467--78 "General Principles and General Provisions for Chemical Analysis of Metallurgical Products". Method Summary
The sample is burned at high temperature in an oxygen flow, sulfur generates sulfur dinitride, which is absorbed by iodine solution and determined by conductivity method. 2 Reagents and Materials
2.1 Oxidation: When the copper wire is separated, it should be treated as follows. Cut the copper wire of the cable into pieces, remove the outer layer dirt with dilute nitric acid, wash with distilled water, dry for 1 minute, put it in a porcelain boat, burn it at 1250℃ with oxygen for 10 minutes, take it out, pour it into the alloy mill, hammer it, pass through a 100-meter sieve, and use it.
2.2 Zinc oxide: Put the analytical pure zinc oxide into a porcelain mill and burn it in a high-temperature furnace at 800-900℃ for 2 hours, take it out, cool it, and grind it. Pass through a 100-meter sieve. If it still does not meet the requirements, put it into a porcelain boat again, burn it at 1250℃ with oxygen for 15 minutes, take it out, cool it, grind it, pass through a 100-meter sieve, and use it.
2.3 Iodine solution: Take 5g iodine and place it in a brown bottle pre-filled with 2000ml double distilled water. Stir it regularly and leave it for several days. It can be used after the value is less than 20s.
2.4 Alkaline potassium permanganate solution (3%): Take 3g potassium permanganate and dissolve it in 100ml potassium hydroxide solution (10%). 2.5 Sulfur exhaust solution
2.5.1 Preparation: Take 0.4430g of anhydrous sodium sulfate (pre-dried at 105-110℃ for 1h, placed in a desiccator, and cooled to room temperature), dissolve in sub-hot distilled water, transfer to a 1000ml volumetric flask, dilute with water to the mark, mix, this solution contains about 1.1mg sulfur per ml
2.5.2 Calibration: Take 25.00ml of sulfur standard solution (2.5.1), place in a 400ml beaker, add 2 drops of 1% orange indicator (0.1%), and use hydrochloric acid (1+ 1) Neutralize 1 until the methyl group turns red, add 2 ml excess, then dilute with water to about 200 ml, boil for a few minutes, remove, slowly add 10-15 ml nitrogen solution (10%) under constant stirring, keep warm for about 1 hour, let stand for 2-3 hours (preferably overnight), filter with a fixed test filter paper, wash the beaker with hot water, and wash the precipitate 10-15 times (wash until there is no nitrogen ion), transfer the precipitate and the paper to a glass with a known manganese content, place in a new temperature furnace, first carefully calcify at low temperature, then heat up to 800-850℃ and burn for 40 minutes. Cool slightly, place in a desiccator, cool to room temperature and weigh, and do a hardness test at the same time to calibrate the calibration results. The concentration of sulfur standard solution after determination is calculated according to formula (1): www.bzxz.net
C=Km2mt)(m.\ms)J×0. 374
Wherein: (--concentration of sulfur standard solution after determination, g/ml: mE extracted mass,;
m2 together with sulfur quality. g:
National Bureau of Standards 1984-0412 issued
1985-03-01 implementation
ms——Shengkongshan quality rat, g:
GB 4324.23--84
m"\ground garbage and air test sulfur lock mass, g+[--——transfer sulfur standard solution volume, ml; 0.1374--·barium sulfate exchange sieve for sulfur conversion factor. 2.6 gas.
2.7 porcelain purchase: length 88mm (pre-1250 (now burned for 5mn, taken out to eliminate cooling, placed in a dryer for 1 month, cooled to room temperature, standby). 28
m17mmx.600m
conductivity meter: conductivity is 50mS~0.05uS six mouse range. Super thermostat
Diagram of combustion conductivity measurement device and Figure 2
Figure 1 Diagram of combustion-conductivity measurement device
! Oxygen bottle, 2-buffer bottle, 3-washing bottle (containing sodium manganate solution): 4-water (containing anhydrous CuCl2) + 5-micro oscillometer (0-1000 nml/min) 6-combustion type: ?-volt thermometer (0-1600), 8-27 type conductivity meter: 9-super thermostat: 10-three-way valve; 11-conductivity absorption cell, 2-titration 7
4 sample
GB 4 2
Conductivity absorption cell
4.1 The sample should be crushed and passed through a 120-mesh screen. 4.2 Weigh the sample and place it in a porcelain boat, place it in a high-temperature furnace and sinter it into tungsten trioxide, and then measure it. The sintering conditions are shown in Table 1Table 1
Tender sintering conditions
Type of ammonium tungstate
Temperature,
Time, min
5 Analysis steps
5.1 Quantity to be measured
GB 4824.23—B4
Three samples should be weighed for measurement during analysis. The measured values ​​should be within the allowable difference in the room, and the average value should be taken. 5.2 Sample quantity
According to Table 2 Weigh the sample.
Sample name
Tungsten trioxide
Ammonium paratungstate
5.9 Blank test
Carry out a blank test together with the sample.
Sulfur, %
0,001~0. 01
0. 001 ~ 0. 01
0.0007~0.0080
Sample amount, g
0.5000 ~1.000
0.5000-1.00
0.5000~1.cpo
Before measuring the sample or when replacing a new porcelain tube, use about 50% sulfur to saturate the system through combustion. Place the sample (5.2) in the porcelain boat (2.7), and then weigh 0.5g of copper oxide (2.1) and 2g of zinc oxide (.2) to cover it. When the furnace temperature reaches 1250℃ and the thermostat is 35℃, put a silicone plug on the porcelain tube mouth, pass oxygen for 5min (atmosphere flow rate is 4p0ml/min), read the conductivity value starting number, push the porcelain boat into the high temperature area of ​​the porcelain tube, plug it with a silicone plug, pass oxygen for 10min (oxygen flow rate is 400ml/min), absorb it through the constant temperature absorption cell, and read the conductivity value end number from the conductivity meter after 10min. 5.4.3 Turn the two-way piston on the thermostat to the drain hole, and discharge the iodine solution that has been measured by oxygenation. After discarding it, turn the three-way piston to the vent hole and put 20ml of saturated iodine (2.3) in the burette to wash the device once, fill it, put 20ml of saturated iodine solution (2.3), and after oxygenation for 5min, record the initial reading for the next measurement. 54.4 Use the measured conductivity value to find the corresponding sulfur content from the working line. 5.5 Drawing of the working curve
615.1 Take 0.00, 0.02, 0.05, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70ml of sulfur standard solution (2.5), place them in ~ groups of porcelain boats respectively, and dry them under infrared lamp for 2h. The following shall be carried out according to 5.4.1 to 5.4.3. Take the sulfur content as the horizontal axis and the conductivity value as the vertical axis. Draw the working curve.
6 Calculation of analysis results
Calculate the conductivity value according to formula (2):
Conductivity value = (b-)-
Starting point conductivity value, uS
Where: a—
6—End point conductivity value, uS,
c——Measured empty conductivity value, uS.
Calculate the sulfur percentage according to formula (3):
Formula: m,-
Allowance
GB 4324.28-84
S (%)=
-obtained conductivity value Sulfur content found on the working curve,:-sample weight, g.
The difference between the analysis results of the laboratories should not be greater than the allowable sulfur content listed in Table 3
0.0005~0.0015
>0.0015~0.0025
0.0025~0.0050
0.005-0.012
Additional Notes:
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China and drafted by Zhuzhou Cemented Carbide. This standard was drafted by Zhuzhou Cemented Carbide Factory. The main drafter of this standard is Huang Cheng.
Allowance
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