Some standard content:
National Standard of the People's Republic of China
Industrial sodium carbonate
Sodium carbonate for industrial use1 Subject content and scope of application
GB210—92
Substitute 218-±2373-89| |tt||This standard specifies the technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of industrial sodium carbonate. This standard applies to industrial sodium carbonate produced by ammonia-alkali method, combined alkali method or other methods using industrial salt or natural alkali as raw materials. This product is mainly used in chemical, glass, metallurgy, papermaking, printing and dyeing, synthetic detergents, petrochemical and other industries. Molecular formula: NazCO:
Relative molecular mass: 105.99 (according to the 1987 international relative atomic weight) 2 Reference standards
GB191
GB601
GB602
GB603| | tt | |Chemical reagents
Preparation of preparations and products used in test methodsChemical reagents
Expression method and judgment method of limit values ??GB3049
GB3050
GB3051
GB6003 | | tt | | GB6678 | General method for determination of chemical content Potentiometric titration method General method for determination of fluorochloride content in inorganic chemical products Mercury method test sieve
General principles for sampling of chemical products
Laboratory water specifications
Plastics Woven bags
Composite plastic woven bags
GB10454
Flexible container bags
GSBG12001 Industrial sodium carbonate national standard sample 3 product classification
Industrial sodium carbonate points There are three categories:
Category 1 is heavy sodium carbonate for special industrial use. Suitable for manufacturing picture tube glass bulbs, float glass, optical glass, etc. Category I is industrial sodium carbonate produced from general industrial salt and natural alkali. Including light sodium carbonate and heavy sodium carbonate. Category II is industrial sodium carbonate produced by using sodium sulfate type brine salt as raw material and combined with alkali method. Including light sodium carbonate and heavy sodium carbonate. 4Technical Requirements
4.1 Appearance: Category 1 is white fine particles. ! , Class I light sodium carbonate is white crystalline powder, and heavy sodium carbonate is white fine particles. 4.2 Industrial sodium carbonate should meet the requirements in the following table: State Bureau of Technical Supervision approved 1993-09-01 implementation on 1992-12-01
item
indicator
total alkali content (in NazCO, (calculated), %
Fluoride (calculated as NaCI) content, %
Iron (Fe) content, %
Sulfate (calculated as SO,) content, %||tt ||Water-insoluble content, %
Loss on ignition, %
Bulk density\, g/mL
Particle size
180μm
Screen residue , %
1.18mm
>
Class 1
Premium product
99.2
0.50
0.004||tt ||0.03
0.04
0.8
0. 85
75.0
2.0
GB210-92
Class 1
Premium product
99.2
0.70
0.004
0.03)
0.04
0.8
0.90
70.0
Note: 1) It is an ammonia-alkali method control item and can be inspected when required by the user. 2) Inspection results during packaging.
3) is a heavy sodium carbonate control project.
5 test method
First-class product
98.8
0.90
0.006
0.10
1.0||tt| |0.90
65.0
refers to
qualified products
98.0
1.20
0.010
0.15
1.3
0. 90
60.0
standard
premium product
99.1
0.70
0.004||tt| |0.04
0.8
0. 90
70.0
■Class
First-class product
98.8
0.90| |tt||0.006
0.10
1.0
0.90
65.0
Qualified product
98.0
1.20|| tt||0.010
0.15
1.3
0.90
60.0
The reagents and water used in this standard refer to Analytical reagents and grade three water specified in GB6682. The standard solutions, impurity standard solutions, preparations and products required in the test shall be prepared in accordance with the provisions of GB601, GB602 and GB603 unless other provisions are noted.
5.1 Determination of total alkali content
This method refers to the international standard ISO740-1976 "Sodium carbonate for industrial use - Determination of total alkali content 5.1.1 Method summary
Using methyl bromide Phenol green-methyl red mixture was used as indicator, and the total alkali was titrated with hydrochloric acid standard titration solution. 5.1.2 Reagents and materials
5.1.2.1 Hydrochloric acid (GB622) standard titration solution: c (HCl) about 1 mol/L 5.1.2.2 Bromocresol green (HG3—1220)-methyl red (HG3— 958) Mix the indicator fluid. 5.1.3 Instruments and equipment
5.1.3.1 Weighing bottle: $30mm×25mm; or porcelain crucible; capacity 30mL. 5.1.4 Analysis steps
Titration method》.
Weigh about 1.7g of the sample, place it in a weighing bottle or porcelain with constant weight, move it into an oven or high-temperature furnace, and dry it to constant weight at 250~270℃, accurate to 0.0002g. Pour the sample into the Erlenmeyer flask, and then accurately weigh the mass of the weighing flask or porcelain pot. The difference between the two weighings is the mass of the sample. Dissolve the sample in 50 mL of water, add 10 drops of bromocresol green-methyl red mixed indicator solution, and titrate with hydrochloric acid standard titration solution until the test solution changes from green to dark red. Boil for 2 minutes, cool and continue to titrate until dark red. Do a blank test at the same time.
5.1.5 Expression of analysis results
The total alkali amount expressed as mass percentage (calculated as NazCO:) X, calculated according to formula (1): X =c(V-Vo)×0 . 053 00
m
5.3c(VV.)
m
Where: c
The actual concentration of hydrochloric acid standard titration solution, mol/ LX100
(1)
GB210-92
-The volume of hydrochloric acid standard titration solution consumed by titration, mL; V
V. —The volume of the hydrochloric acid standard titration solution consumed by the blank test, mL; m--the mass of the sample, g;
0.05300-is equivalent to 1.00mL hydrochloric acid standard titration solution Cc (HC1) = 1.000mol/L), Mass of sodium carbonate in grams.
5.1.6 Allowable difference
Take the arithmetic mean of the parallel measurement results as the measurement result, and the absolute difference of the parallel measurement results shall not be greater than 0.2%. 5.2 Determination of chloride content
5.2.1 Mercury measurement method
This method refers to the international standard ISO742-1973 "Sodium carbonate for industrial use - Determination of chloride content-5.2.1.1 Method summary| |tt||Same as Chapter 2 of GB3051.
5.2.1.2 Reagents and materials
5.2.1.2.1 Nitric acid (GB626) solution: 1+1; Nitric acid (GB626) solution: 1+7;
5.2.1.2. 2
Sodium hydroxide (GB629) solution: 40g/L; 5.2.1.2.3
5.2.1.2.4 Mercury nitrate standard titration solution: c (No. Hg(NO)·H,O) is about 0.05mol/L. Prepare and calibrate according to Article 4.9 of GB3051;
5 Bromophenol Blue (HG3-1224) indicator liquid: 1g/L; 5.2.1.2.5
: diphenyl azocarbon hydrazide indicator liquid 5g/L. 5.2.1.2.6
5.2.1.3 Instruments and equipment
5.2.1.3.1 Microburette: The graduation value is 0.01 or 0.02mL. 5.2.1.4 Analysis steps
5.2.1.4.1 Preparation of reference solution
Mercury measurement method》.
Add 40mL water and 2 drops of bromophenol blue indicator solution into a 250mL Erlenmeyer flask. Add nitric acid solution (5.2.1.2.2) dropwise until the solution changes from blue to yellow, then add 2 to 3 drops more. Add 1 mL of diphenyl azocarbon hydrazide indicator solution, titrate with mercury nitrate standard titration solution until the solution changes from yellow to purple, and record the volume of the mercury nitrate standard titration solution used. Prepare this solution just before use. 5.2.1.4.2 Determination of sample
Weigh about 2g of sample, accurate to 0.01g, and place it in a 250mL Erlenmeyer flask. Add 40 mL of water to dissolve the sample, add 2 drops of bromophenol blue indicator solution, dropwise add nitric acid solution (5.2.1.2.1) to neutralize until the solution turns yellow, then add dropwise sodium hydroxide solution (5.2.1.2.3) until the test When the solution turns blue, add nitric acid solution until the solution turns yellow and add 2 to 3 drops more. Add 1 mL of diphenyl azocarbon hydrazide indicator solution and titrate with mercury nitrate standard titration solution until the solution changes from yellow to purple-red, which is the same color as the reference solution (5.2.1.4.1), which is the end point. Save the waste liquid after titration and process it according to the provisions of Appendix D of GB3051. 5.2.1.5 Expression of analysis results
The chloride (calculated as NaCI) content X expressed as mass percentage is calculated according to formula (2): x
100
584.4c(VV.)
m(100-X.)
where: c-
mercuric nitrate standard titration solution The actual concentration of mercuric nitrate standard titration solution, mol/L; V——the volume of mercury nitrate standard titration solution consumed in the titration, mL; V. —The volume of the mercury nitrate standard titration solution consumed in the preparation of the reference solution, mL; (2)
m-the mass of the sample, g
X.
Loss on ignition measured according to 5.6, %;
0.05844-
GB210-92
with 1.00ml mercury nitrate standard titration solution (chlorination of cl The mass of sodium.
5.2.1.6 Allowable difference
Hg (NO,)2·H,O)=1.000mol/L) equivalent, expressed in grams, take the arithmetic mean of parallel measurement results. For measurement results, the absolute difference between parallel measurement results shall not be greater than 0.02%. 5.2.2 Potentiometric titration
This standard refers to the international standard ISO6227-1982 "Industrial Chemical Products - General Method for Determination of Chloride Ions - Potentiometric Titration".
5.2.2.1 Method summary
Same as Chapter 2 of GB3050.
5.2.2.2 Reagents and materials
5.2.2.2.1 Sodium chloride standard solution (GB1253): c(NaCI)=0.05mol/L standard solution. Weigh 2.9225g of standard sodium fluoride that has been dried to a constant weight at 500-600°C, accurate to 0.0002g, place it in a beaker, add water to dissolve, then transfer to a 1000mL volumetric flask, add water to dilute to the mark, and shake well. 5.2.2.2.2 Silver nitrate (GB670) standard titration solution: c(AgNO,) is about 0.05mol/L. Weigh about 8.75g of silver nitrate, dissolve it in 1000mL of water, and shake well. The solution is stored in a brown bottle. Use a pipette to remove 5 mL of sodium chloride standard solution, place it in a 100 mL beaker, put in an electromagnetic stirrer, place the beaker on the electromagnetic stirrer, start the stirrer, and add 2 drops of bromophenol blue indicator solution (5.2.1.2 .5) Add nitric acid solution (5.2.1.2.1) dropwise until the test solution turns yellow. Insert the measuring electrode (5.2.2.3.3) and reference electrode (5.2.2.3.2) into the solution, connect the electrodes to the potentiometer, adjust the zero point of the potentiometer, and record the starting potential value. Titrate with silver nitrate standard titration solution. First add 4.00mL, then add 0.10mL gradually, record the total volume and the corresponding potential value E after each addition of the silver nitrate standard titration solution, and calculate the continuously increasing potential values ??A, E and △, E. The maximum value of A and E is the end point of the titration. Record another potential value E after the end point. See Appendix C of GB3050 for the recording format. The volume V of the silver nitrate standard titration solution consumed during the titration to the end point is calculated according to formula (3): h
FXV,
V=Vo+www.bzxz.net
where: V. — Potential increment value △, the volume of silver nitrate standard titration solution added before E reaches the maximum value, mL; Vi — Potential increment value △, the volume of silver nitrate standard titration solution added before E reaches the maximum value, mL; b——A, the last positive value of E;
B——△, the sum of the absolute values ??of the last positive value and the first negative value of E (see the example in Appendix C of GB3050 for details). The actual concentration c of the silver nitrate standard titration solution is calculated according to formula (4): where: C2—
The actual concentration of the sodium fluoride standard solution, mol/L; V2—the sodium fluoride removed during titration The volume of the reference solution, mL; V - the volume of the silver nitrate standard titration solution consumed in the titration, mL; 5.2.2.3 Instruments and equipment
5.2.2.3.1 Potentiometer: the accuracy should not be less than 10mV/div , the measuring range is -500~+500mV; (3)
(4)
5.2.2.3.2 Reference electrode: double liquid junction saturated calomel electrode, filled with saturated potassium chloride solution , during titration, the outer tube contains saturated potassium nitrate solution and is connected to the calomel electrode.
5.2.2.3.3 Measuring electrode: silver electrode or silver sulfide-coated silver electrode, (see Appendix A of GB3050 for preparation method); 5.2.2.3.4 Microburette: graduation value is 0.01 or 0.02mL. 5.2.2.4 Analysis steps
GB210-92
Weigh an appropriate amount of sample (2g for Category 1, 1g for Category I and Category 1), accurate to 0.01g. Place it in a 100mL beaker, add 40mL water to dissolve. The following operations are carried out according to the provisions of (5.2.2.2.2), starting from "putting in the electromagnetic stirrer" and ending with "continue to record a potential value E after the end point", but No longer add 4.00mL of silver nitrate standard titration solution first. Do a blank test at the same time.
5.2.2.5 Expression of analysis results
Chloride (calculated as NaCl) content X expressed as mass percentage, calculated according to formula (5): c(V-Vo)X0. 058 44× 100
X,
(100-X.)
m
100
584.4c(VV)
m(100- X. )
Where: c--actual concentration of silver nitrate standard titration solution, mol/L; V
The volume of silver nitrate standard titration solution consumed in a titration, mL; The volume of silver nitrate standard titration solution consumed in the blank test, mL; V.
X. ——Loss on ignition measured from 5.6, %; mass of sample, g;
0.05844-
(5)
and 1.00mL silver nitrate standard titration solution c (AgNO,)=1.000mol/L) is equivalent to the mass of sodium chloride expressed in grams.
5.2.2.6 Allowable difference
Take the arithmetic mean of the parallel measurement results as the measurement result, and the absolute difference of the parallel measurement results shall not be greater than 0.02%. 5.3 Determination of iron content
This method refers to the international standard ISO.6685--1982 "Industrial Chemical Products - General Method for Determination of Iron Content 1,10-phenanthroline Spectrophotometry".
5.3.1 Method summary
Same as Chapter 2 of GB3049.
5.3.2 Reagents and materials
Same as Chapter 3 of GB3049.
5.3.3 Instruments and equipment
5.3.3.1 Spectrophotometer: with an absorption cell with a thickness of 3cm. 5.3.4 Analysis steps
5.3.4.1 Drawing of working curve
According to GB3049 Section 5.According to the 3 regulations, select an absorption cell with a thickness of 3cm and its corresponding amount of iron standard solution to draw a working curve. 5.3.4.2 Determination of sample
Weigh 10g sample, accurate to 0.01g, place it in a beaker, add a small amount of water to moisten it, add 35mL hydrochloric acid solution (1 + 1) dropwise, and boil for 3~5 minutes. Cool (filter if necessary), transfer to a 250mL volumetric flask, add water to the mark, and shake well. Use a pipette to take 50mL (or 25mL) of the test solution and place it in a 100mL beaker; take another 7mL (or 3.5mL) of hydrochloric acid solution (1+1) in another beaker and neutralize it with ammonia water (2+3) Finally, use ammonia water (1+9) and hydrochloric acid solution (1+3) together with the test solution to adjust the pH value to 2 (check with precision pH test paper). Move them into 100mL volumetric flasks respectively. The following operations are in accordance with Articles 5.3.2 and 5.3.3 of GB3049. Use a 3cm absorption cell and use water as a reference to measure the absorbance of the test solution and blank test solution. 5.3.5 Expression of analysis results
Iron (Fe) content X expressed as mass percentage, calculated according to formula (6): X
GB210-92
mm.
（100-X.）
100
10(m,一m)
m(100-X.)
X1000||tt || - The mass of iron found from the working curve based on the measured absorbance of the blank test solution, mg; - The mass of the sample contained in the removed test solution, g; X. --Loss on ignition measured according to 5.6, %. 5.3.6 Allowable difference
(6)
Take the arithmetic mean of parallel measurement results as the measurement result. The absolute difference of parallel measurement results: no more than 0.0005% for superior products and first-class products, and no more than 0.001% for qualified products. 5.4 Determination of sulfate content
5.4.1 Barium sulfate gravimetric arbitration method
This method refers to the international standard ISO743-1976 "Industrial Sodium Carbonate - Method".
5.4.1.1 Method summary
-Determination of sulfate content--Dissolve the sample with sulfuric acid lock weight and separate the insoluble matter, precipitate the sulfate into barium sulfate in dilute hydrochloric acid medium, and dissolve the obtained The precipitate is separated, burned at 800 ± 25°C and weighed.
5.4.1.2 Reagents and solutions
5.4.1.2.1 Hydrochloric acid (GB622) solution: 1+1; 5.4.1.2.2 Nitrogen water (GB631);
5.4.1.2 .3 Chloride (GB652) solution: 100g/L; 5.4.1.2.4 Silver nitrate (GB670) solution: 5g/L. Dissolve 0.5g silver nitrate in a small amount of water, add 20mL nitric acid solution (1+1), dilute to 100mL with water, and shake well. 5.4.1.2.5 Methyl orange (HGB3089) indicator liquid: 1g/L. 5.4.1.3 Analysis steps
Weigh about 20g of the sample, accurate to 0.01g, place it in a beaker, add 50mL of water, stir, dropwise add 70mL of hydrochloric acid solution to neutralize and acidify the sample, use medium speed Quantitative filter paper filtration. The filtrate and washing liquid are collected in a beaker, and the volume of the test solution is controlled to about 250 mL. Add 3 drops of methyl orange indicator solution, neutralize with ammonia, then add 6 mL of hydrochloric acid solution to acidify, boil, add 25 mL of barium nitride solution dropwise with constant stirring (complete addition in about 90 seconds), continue to boil for 2 minutes with constant stirring. Place it on a boiling water bath for 2 hours, stop heating, let it stand for 4 hours, filter with slow quantitative filter paper, wash the precipitate with hot water until 10 mL of filtrate is mixed with 1 mL of silver nitrate solution, and it still remains transparent after 5 minutes. Move the filter paper and precipitate into the pre- In a porcelain crucible with constant weight at 800 ± 25°C, ashes are moved to a high-temperature furnace and burned to constant weight at 800 ± 25°C.
5.4.1.4 Expression of analysis results
Sulfate (calculated as SO.) content X expressed as mass percentage. Calculate according to formula (7): X,=mx0:411 6×100
100-X.
m
100
4116m
m(100-X,)
where: m
m
-The mass of barium sulfate after burning, g;
The mass of the sample, g;
The loss on ignition measured according to Article 5.6, %;
X.
0.4116 barium sulfate to sulfate conversion coefficient. (7)
GB210--92
5.4.1.5 Allowable difference
Take the arithmetic mean of the parallel measurement results as the measurement result, and the absolute difference of the parallel measurement results shall not be greater than 0.006% . 5.4.2 Barium sulfate turbidimetric method
5.4.2.1 Method summary
In a slightly acidic medium, use barium chloride to precipitate sulfate ions, and compare it with the barium sulfate standard turbidimetric solution. 5.4.2.2 Reagents and materials
5.4.2.2.1 Barium chloride (GB652) solution: 250g/L; 5.4.2.2.2 Sulfate standard solution: 1mL contains 0.1mg sulfate (SO.); 5.4 .2.2.3 Phenolic acid indicator solution: 10g/L; 5.4.2.3 Analysis steps
Weigh 1g sample, accurate to 0.01g, place it in a 250mL beaker, add 20mL water and 1 drop of phenol indicator solution, Add hydrochloric acid solution (5.4.1.2.1) dropwise to neutralize to neutrality and an excess of 2 mL, boil for 2 minutes, cool (filter if necessary), and transfer to a 50 mL colorimetric tube. At the same time, according to the sulfate content in the sample, take 3 to 4 portions of the sulfate standard solution and place them in 50mL colorimetric tubes, with a difference of 0.5mL between each portion (according to the sulfate content in the sample, it can be appropriately reduced or expanded. interval). Add 20mL water and 2mL hydrochloric acid solution (5.4.1.2.1) respectively.
Add 10mL of chloride lock solution (5.4.2.2.1) into the sample tube and standard tube at the same time, add water to the mark, and shake well. Compare the turbidity of the standard tube and the sample tube after placing it in a 40-50°C water bath for 20 minutes. Calculate the amount of sulfate in a standard tube with a turbidity equivalent to that of the test tube. When the turbidity of the test tube is between the turbidity of the three standard tubes, the calculation is based on the average of the sulfate content in the two standard tubes. 5.4.2.4 Expression of analysis results
Sulfate (measured as SO,) content X expressed as mass percentage, calculated according to formula (8): m, || m Mass, g.
m
5.5 Determination of water-insoluble matter content
5.5.1 Method summary
Dissolve the sample in water at 50±5℃, filter the insoluble matter, Wash, dry and weigh. (8)
5.5.2 Reagents and materials
5.5.2.1 Pickled asbestos (HG3--1062): Take an appropriate amount of pickled asbestos, soak it in 1+3 hydrochloric acid solution, boil for 20 minutes, Filter with Buchner funnel and wash until neutral. Then soak in 100g/L anhydrous sodium carbonate (GB639) solution and boil for 20 minutes, filter with a Buchner funnel and wash until neutral (check with phenolic acid indicator solution). Make a paste with water and set aside. 5.5.2.2 Phenol indicator liquid: 10g/L.
5.5.3 Instruments and equipment
5.5.3.1 Gu's crucible: capacity 30mL.
5.5.4 Analysis Steps
Place the Gustav's crucible on the suction filtration bottle, spread a layer of pickled asbestos evenly on the upper and lower sides of the sieve plate, and press it with a flat glass rod while suction filtration. Each layer is about 3mm thick. Wash with 50±5℃ water until the filtrate does not contain asbestos wool. Move the sugar pot into the drying box, dry it at 110±5℃ and weigh it. Repeat washing and drying to constant weight.
Weigh 20~40g sample, accurate to 0.01g, place it in a beaker, add 200~400mL of water at about 40°C to dissolve, and maintain the temperature of the test solution at 50±5°C. Filter with a constant-weight Gustenberg crucible, and wash the insoluble matter with water at 50 ± 5°C until the colors shown after adding 2 drops of phenolphthalein indicator solution to 20 mL of washing solution and 20 mL of water are consistent. Move the Gu's sugar cauldron together with the insoluble matter into a drying oven and dry to constant weight at 110 ± 5°C.
5.5.5 Expression of analysis results
GB210-92
The water-insoluble matter content X expressed as mass percentage is calculated according to formula (9): X,
—mass of water-insoluble matter, g;
where: m,-
m—mass of sample, g;
X. ——Loss on ignition measured according to 5.6, %. 5.5.6 Allowable difference
m
m,
X100
(100-X.)
100
m,×104
m(100-X,)
(9)
Take the arithmetic mean of the parallel measurement results as the measurement result. The absolute difference of the parallel measurement results: excellent product, first class The quality products shall not exceed 0.006%, and the qualified products shall not exceed 0.008%. 5.6 Determination of loss on ignition
This method refers to the international standard ISO745-1976 "Determination of Sodium Carbonate for Industrial Use".
5.6.1 Method summary
- Mass loss and non-volatile matter at 250~270℃. The sample is heated to constant weight at 250~270℃. Free water is lost and sodium bicarbonate is decomposed during heating. Calculate the loss on ignition from the water and carbon dioxide produced.
5.6.2 Instruments and equipment
5.6.2.1 Weighing bottle: 930mm×25mm or porcelain crucible, with a volume of about 30mL. 5.6.3 Analysis steps
Weigh about 2g of the sample, accurate to 0.0002g, place it in a weighing bottle or porcelain with constant weight, move it into an oven or high-temperature furnace, and heat it to 250~270℃. Constant weight.
5.6.4 Expression of analysis results
Loss on ignition X expressed as mass percentage. Calculate according to formula (10): X.
The mass lost when the sample is heated, g;
Where: m-
m
The mass of the sample in g.
5.6.5 Allowable difference
m
The difference is not greater than 0.04%. 5.7 Determination of bulk density
5.7.1 Method summary
(10)
A certain amount of sample passes through a conical funnel and enters a cylindrical tank of known volume. Determine the mass of the sample required to fill the tank. 5.7.2 Instruments and equipment
5.7.2.1 The measuring device for bulk density
is as shown in the figure.
5.7.3 Measurement steps
Install the bulk density measuring device as shown in the figure. Weigh the mass of the material tank, accurate to 1g.
2
GB210—92
$112
040
q89
Bulk density measuring device diagram
1—Material Tank; 2--stand; 3--funnel
O
Close the bottom of the funnel, fill the sample naturally, scrape off the higher part with a ruler, and put the known mass material tank, open the lower bottom of the funnel, so that all the sample will automatically flow into the material tank, scrape off the raised part with a ruler (do not move the material tank before scraping it flat), and weigh the mass of the sample and the material tank, accurate to 1g.
5.7.4 Expression of measurement results
The bulk density β expressed as the mass per unit volume is calculated according to formula (11): m,
m
V|| tt||In the formula: m-the mass of the material tank and the sample, g
the mass of the material tank, g;
m
V——the volume of the material tank, mL.
5.7.5 Allowable difference
Take the arithmetic mean of the parallel measurement results as the measurement result, and the absolute difference of the parallel measurement results shall not be greater than 0.02g/mL. 5.8 Determination of particle size
5.8.1 Instruments and equipment
5.8.1.1 Test sieve (GB6003): R40/3 series, Φ200×50/1.18mm, 4200×50/180um, with sieve Bottom and screen cover. 5.8.1.2 Vibrating screening machine.
5.8.2 Measurement steps
(11)
Weigh about 50g of sample, accurate to 0.1g. Put it into the test sieve with the sieve bottom installed (the test sieve hole diameter is 1.18mm and 180μm for Category 1, and 180um for Category I and 1), cover the sieve cover, and vibrate the sieve horizontally manually for 2 minutes, vibrating 80 times per minute, or at Sieve with a vibrating sieve machine for 5 minutes, and weigh the mass of the residue, accurate to 0.1g.
5.8.3 Expression of measurement results
Sieve residue X expressed as mass percentage. Calculate according to formula (12):1g.
5.8.3 Expression of measurement results
Sieve residue X expressed as mass percentage. Calculate according to formula (12):1g.
5.8.3 Expression of measurement results
Sieve residue X expressed as mass percentage. Calculate according to formula (12):
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