HG 2958.1-1988 Determination of strontium and calcium content in celestite ore EDTA volumetric method
Some standard content:
Chemical Industry Standard of the People's Republic of China
Determination of strontium and calcium contents in celestite ore-EDTA volumetric method
Celestiteores-Determinationof strontiumand calciumcontents-EDTAvolumetricmethodSubject content and scope of application
UDC549.761.3
：543.06
HG/T2958.1-1988 (1997)
Replaces GB9018.1~88
This standard specifies the EDTA volumetric method for the determination of strontium and calcium contents in celestite ore. This standard is applicable to celestite ore products with a strontium oxide content greater than 10% and a calcium oxide content greater than 5%. 2 Method Summary
The sample is melted with sodium carbonate and sodium hydroxide to convert strontium, barium, calcium, etc. into carbonates and separate sulfate ions. The precipitate is dissolved with hydrochloric acid, and ammonia water is separated from the disturbing elements. At pH ~ 10, EDTA is used to complex strontium barium and other alkaline earth metals with chrome black T-naphthol green B-dalcho yellow as indicators. In the presence of potassium sulfate, an excess of magnesium sulfate is used to replace the strontium and barium in the EDTA complex to generate the corresponding sulfate, and the excess magnesium ions are titrated with EDTA standard solution. The total amount of strontium and barium is calculated from the magnesium consumed in the replacement reaction, and the barium content is subtracted to obtain the strontium oxide content.
In the test solution after the determination of the total amount of strontium and barium, oxalic acid is added to the calcium to form calcium oxalate precipitation, which is filtered and dissolved with hydrochloric acid. A certain amount of magnesium solution is added, and at pH 10, the total amount of calcium and magnesium is titrated with chrome black T-naphthol green B-dalcho yellow as indicators and EDTA standard solution. The calcium oxide content is obtained by subtracting the magnesium content. Www.bzxZ.net
3 Reagents and solutions
3.1 Anhydrous sodium carbonate (GB639~77);
3.2 Sodium carbonate; 5% solution;
3.3 Sodium carbonate washing solution: 1% solution;
3.4 Sodium hydroxide ((GB629-81);
3.5 Sodium peroxide;
3.6 Triethanolamine: 1+4 solution;
3.7 Hydrochloric acid (GB622-77): 1+1 solution; 3.8 Hydrochloric acid: 1+5 solution;
3.9 Hydrochloric acid: 1+9 solution;
Ammonia water (GB631-77);
Ammonia water: 1+1 solution;
Methyl red (HG3-958-76): 0.1% ethanol solution; Anhydrous ethanol (GB678-78);
Ethanol : 1+4 solution;
Sodium diethyldithiocarbamate (copper reagent) (HG3-962-76): 3.16
Potassium sulfate (HG3-920-76);
Approved by the Ministry of Chemical Industry of the People's Republic of China on March 21, 1988, implemented from December 1, 1988
3.17 Ammonium chloride (GB658-77);
HG/T2958.1-1988(1997)
3.18 Ammonium nitride washing solution: 1% solution. Weigh 1g ammonium chloride (3.17) and dissolve it in 100ml water, add 1~2 drops of ammonia water (3.11); 3.19 Ammonium chloride-ammonia water buffer solution (pH~10): Weigh 67.5g ammonium chloride (3.17) and dissolve it in water, add 570ml ammonia water (3.10), and dilute with water To 1000ml, shake well; 3.20 Magnesium sulfate (Shanghai Q/HG22-119-81); 3.21 Magnesium sulfate solution: c (MgSO.) = 0.08mol/L. Weigh 9.5g magnesium sulfate (3.20) and dissolve it in 200ml water, transfer it to a 1000ml volumetric flask, dilute it to the mark with water, and shake well; 3.22 Magnesium sulfate solution: c (MgSO4) = 0.03mol/L. Weigh 3.6g magnesium sulfate (3.20) and dissolve it in 200ml water, transfer it to a 1000ml volumetric flask, dilute it to the mark with water, and shake well; 3.23 Chrome black T indicator solution: Weigh 0.2g Chrome black T and dissolve it in 10ml ammonia water (3.10) and 40ml anhydrous ethanol (3.13). After it is completely dissolved, store it in a brown bottle (use period 15d); 3.24 Naphthol green B-Dad yellow indicator solution: Weigh 0 0.02g naphthol green B and 0.08g dacho yellow are dissolved in 50ml water, and 2~4 drops of ammonia water (3.11) are added;
3.25 Zinc standard solution: c (Zn) = 0.02000mol/L. Weigh 1.3076g of metal zinc (99.90%) with the surface oxide film removed, dissolve in 20ml hydrochloric acid (3.7), evaporate to 10ml after complete dissolution, cool, transfer to a 1000ml volumetric flask, dilute to the scale with water, and mix well;
3.26 Disodium ethylenediaminetetraacetate (EDTA) (GB1401-78); 3.27 EDTA standard solution: c (EDTA) = 0.02mol/L; 3.27.1 Preparation: Weigh 14.8g EDTA (3.26) and dissolve in 200ml hot water, cool, dilute to 2000ml with water, and shake well. 3.27.2 Calibration: Pipette 20.00 ml zinc standard solution (3.25) into a 250 ml beaker, add 50 ml water, 15 ml ammonium chloride-ammonia buffer solution (3.19), 4-5 drops of chrome black T indicator solution (3.23), 2-3 drops of naphthol green B-darkenol yellow indicator solution (3.24). Titrate with EDTA standard solution (3.27) until the solution turns green. 3.27.3 Calculation of concentration:
The concentration of EDTA (c) is calculated according to formula (1): GiVi
Where: V.—
-the volume of zinc standard solution absorbed, ml; V—the volume of EDTA standard solution consumed during titration, ml; c.—the concentration of zinc standard solution, mol/L. 3.28 Zinc acetate [Zn (CH, COO) 2.2H, O (HG3-1098-77); 3.29 Zn-EDTA solution;
*3.29.1 Preparation: Weigh 21.9g zinc acetate (3.28), 37.2g EDTA (3.26) and dissolve in 500ml water and 100nl ammonia (3.11), dilute to 1000ml with water, shake the spoon. 3.29.2 Calibration: Take 10.00ml of the above solution, add 60~80ml water, 10ml ammonia (3.11), 4~5 drops of chrome black T indicator (3.23), 2-3 drops of naphthol green B-dadan yellow indicator (3.24). Titrate with EDTA standard solution (3.27) until the solution just turns green. At this time, 0.3~0.4ml of EDTA standard solution is consumed. Otherwise, add a measured amount of zinc acetate (3.28) or EDTA (3.26) to adjust.
3.30 Oxalic acid (HG3-988-76): 10% solution; 3.31 Bromophenol blue (HG3-1224-79): 0.4% solution; 3.32 Malachite green: 0.1% solution.
4 Sample
The sample passes through a 0.075rmm sieve (GB6003-85), is dried at 105~110℃ to constant weight, and is placed in a desiccator to cool to room temperature. 46
5 Analysis steps
HG/T2958.1-1988（1997）
5.1 Weigh 0.4g of sample (accurate to 0.0002g), put it into a silver crucible pre-paved with 3g of anhydrous sodium carbonate (3.1), mix carefully, add a little sodium peroxide (3.5), 4g of sodium hydroxide (3.4), cover the crucible (leave a gap). Place the crucible in a muffle furnace, slowly raise the temperature from low temperature to 500℃, stay for 10min, continue to raise the temperature to 700～750℃, keep for 30～40min, take out and cool. Place it in a 250ml beaker containing 100ml of sodium carbonate solution (3.2), add 15ml of triethanolamine (3.6), cover with a surface band, and heat on a hot plate for leaching (slightly boiling for more than 1h). Wash the crucible with water [if necessary, use 2-3 drops of hydrochloric acid (3.9) to dissolve the residue on the crucible wall]. Filter with dense filter paper, wash the beaker with sodium carbonate washing solution (3.3) 4-5 times, and wash the precipitate more than 12 times (wash until there is no silver sulfate). Collect the filtrate in a 400ml beaker. This filtrate is solution A, which is used for the determination of sulfate content. 5.2 Use a glass rod to carefully transfer most of the precipitate on the filter paper into the original beaker, cover the funnel with a watch glass, use 12ml hydrochloric acid (3.8) to dissolve the precipitate on the filter paper in the original beaker, and wash the filter paper with about 80ml hot water [containing a few drops of hydrochloric acid (3.8)]. Move the beaker to an electric stove (press a small piece of filter paper on the end of the glass rod), heat and boil for 2-3 minutes to drive off all carbon dioxide. Remove it, add 1 drop of methyl red indicator solution (3.12), add ammonia water (3.11) until the solution turns yellow and add 4 drops in excess, add 0.5g of copper reagent (3.15), continue heating for a while, remove, and filter the precipitate with medium-speed quantitative filter paper into a 200ml volumetric flask after it condenses. Wash the beaker 34 times with hot ammonium chloride washing solution (3.18), wash the precipitate 8-10 times, add hydrochloric acid (3.8) to the filtrate until the solution turns red and then add 1-2 drops in excess. After cooling, dilute with water to the scale and shake well. This solution is solution B.
5.3 Determination of strontium:
5.3.1 Take 50.00ml of solution B prepared in 5.2 and place it in a 250ml beaker (add 20ml of water to the blank solution), add 10ml Zn-EDTA solution (3.29), 10ml ammonia water (3.11), 4-5 drops of chrome black T indicator solution (3.23), 3-4 drops of naphthol green B-da yellow indicator solution (3.24), and titrate with EDTA standard solution (3.27) until the solution turns bright green (ignore the reading). Accurately add 10.00ml magnesium sulfate solution (3.21) and 2g potassium sulfate (3.16), stir to dissolve, move the beaker to the electric stove, heat and slightly boil for 10min, remove, and quickly cool to room temperature with cold water. Add 15ml anhydrous ethanol (3.13) while stirring, let it stand for a while, filter with dense filter paper, collect the filtrate in a 250ml beaker, and wash the beaker and precipitate with 25ml ethanol (3.14) in batches (after washing the beaker with about 2ml of washing liquid each time, rinse along the filter paper). 5.3.2 Add 10ml ammonia water (3.11) to the filtrate, heat to 60~80℃, add 3 drops of chrome black T indicator solution (3.23), 2 drops of naphthol green B dadan yellow indicator solution (3.24), and titrate with EDTA standard solution (3.27) until the solution turns pure blue as the end point. Record the volume of EDTA standard solution consumed.
5.4 Determination of calcium:
Add an excess of 0.5 ml of EDTA standard solution (3.27) to the solution after titration in 5.3.2, move the beaker to a hot plate and heat to evaporate to 120 ml. Add 5 ml of hydrochloric acid (3.7), 20 ml of oxalic acid solution (3.30), heat to boiling, add 2 to 4 drops of bromophenol blue indicator solution (3.31), add water (3.11) under constant stirring, neutralize until the solution turns purple (pH~4), and keep warm at 70~80°C for 15~20 minutes. After the solution is clarified, filter it with dense filter paper, wash the beaker with water 4 times, and wash the precipitate 5 to 6 times. Open the filter paper and stick it to the original beaker wall. First rinse the precipitate into the beaker with water, then rinse the filter paper with 10 ml of hot hydrochloric acid (3.9) in batches, and finally wash it with water several times until the volume is -100 ml, and discard the filter paper. Heat and boil for 1-2 minutes, accurately add 5-25 ml EDTA standard solution (3.27) (depending on the amount of calcium oxalate precipitation). Stir for a while, add 1 drop of malachite green indicator solution (3.32), neutralize the solution with ammonia water (3.11) to turn blue-green, accurately add 5.00 ml magnesium sulfate solution (3.21) and 10 ml ammonia water (3.11). Heat the solution to 60-80°C, add 3-4 drops of chrome black T indicator solution (3.23) and 2 drops of naphthol green B-dadan yellow indicator solution (3.24), and titrate with EDTA standard solution (3.27) until the solution turns blue-green as the end point. Perform a blank test at the same time.
6 Calculation of analysis results
6.1 The percentage of strontium oxide (X) is calculated according to formula (2): 47
HG/T2958.1-1988 (1997)
X= (V/-Va)×c×0.1036
×100-Ba0%×0.6758
m×200
Wherein: V,—the volume of EDTA standard solution consumed by titrating the blank test solution, ml;—the volume of EDTA standard solution consumed by titrating the test solution, ml; V2
-the concentration of EDTA standard solution, mol/L; the mass of the test sample, g;
—1.00mlEDTA standard solution c(EDTA)=1.000mol/L is equivalent to the mass of strontium oxide, g; 0.6758-
the coefficient of barium oxide converted to oxidation.
6.2 The percentage of calcium oxide (X2) is calculated according to formula (3): X2
(V4-V,)×c×0.05608
m×200
Wherein: V,——the volume of EDTA standard solution consumed by titrating the blank test solution, ml; - the volume of EDTA standard solution consumed by titrating the test solution, ml; V.
-the concentration of EDTA standard solution, mol/L; - the mass of the test sample, g;
7 Allowable difference
—1.00ml EDTA standard solution c (EDTA) = 1.000mol/L is equivalent to the mass of calcium oxide, g. The difference in the results of the measurements within the same laboratory should be less than the values shown in Table 1 and Table 2. Table 1
Strontium oxide
10.00~20.00
>20.00~30.00
>30.00~40.00
Calcium oxide (CaO)
5.00~8.00
>8.00~15.00
Conversion factor of strontium sulfate
SrSO4 (%)=1.7726×SrO (%)
Additional instructions:
This standard is under the jurisdiction of the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Chen Genglin and Gu Lihua. 48
Allowance
Allowance6758
m×200
Wherein: V,--the volume of EDTA standard solution consumed by titrating the blank test solution, ml;--the volume of EDTA standard solution consumed by titrating the test solution, ml; V2
-the concentration of EDTA standard solution, mol/L; the mass of the test sample, g;
-1.00mlEDTA standard solution c(EDTA)=1.000mol/L is equivalent to the mass of strontium oxide, g; 0.6758-
the coefficient of barium oxide converted to oxidation.
6.2Calcium oxide percentage (X2) is calculated according to formula (3): X2
(V4-V,)×c×0.05608
m×200
Wherein: V,——the volume of EDTA standard solution consumed by titrating blank test solution, ml; - the volume of EDTA standard solution consumed by titrating test solution, ml; V.
-the concentration of EDTA standard solution, mol/L; - the mass of sample, g;
7Allowable difference
—1.00ml EDTA standard solution c (EDTA) = 1.000mol/L is equivalent to the mass of calcium oxide, g. The difference in the results of the measurements within the same laboratory should be less than the values shown in Table 1 and Table 2. Table 1
Strontium oxide
10.00~20.00
>20.00~30.00
>30.00~40.00
Calcium oxide (CaO)
5.00~8.00
>8.00~15.00
Conversion factor of strontium sulfate
SrSO4 (%)=1.7726×SrO (%)
Additional instructions:
This standard is under the jurisdiction of the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Chen Genglin and Gu Lihua. 48
Allowance
Allowance6758
m×200
Wherein: V,--the volume of EDTA standard solution consumed by titrating the blank test solution, ml;--the volume of EDTA standard solution consumed by titrating the test solution, ml; V2
-the concentration of EDTA standard solution, mol/L; the mass of the test sample, g;
-1.00mlEDTA standard solution c(EDTA)=1.000mol/L is equivalent to the mass of strontium oxide, g; 0.6758-
the coefficient of barium oxide converted to oxidation.
6.2Calcium oxide percentage (X2) is calculated according to formula (3): X2
(V4-V,)×c×0.05608
m×200
Wherein: V,——the volume of EDTA standard solution consumed by titrating blank test solution, ml; - the volume of EDTA standard solution consumed by titrating test solution, ml; V.
-the concentration of EDTA standard solution, mol/L; - the mass of sample, g;
7Allowable difference
—1.00ml EDTA standard solution c (EDTA) = 1.000mol/L is equivalent to the mass of calcium oxide, g. The difference in the results of the measurements within the same laboratory should be less than the values shown in Table 1 and Table 2. Table 1
Strontium oxide
10.00~20.00
>20.00~30.00
>30.00~40.00
Calcium oxide (CaO)
5.00~8.00
>8.00~15.00
Conversion factor of strontium sulfate
SrSO4 (%)=1.7726×SrO (%)
Additional instructions:
This standard is under the jurisdiction of the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Chemical Industry Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Chen Genglin and Gu Lihua. 48
Allowance
Allowance
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