HG 2958.4-1988 Determination of calcium and magnesium content in celestite ore by atomic absorption spectrometry
Some standard content:
National Standard of the People's Republic of China
Determination of calcium and magnesium contents in celestite ores--- Determination of calcium and magnesium contents -- Atomic absorption spectrometry
Celestite ores--- Determination of calcium and magnesium contents -- Atomic absorption spectrometry Content and scope of application
This standard specifies the determination of calcium and magnesium contents in celestite ores by atomic absorption spectrometry. This standard is applicable to celestite ores with calcium oxide and magnesium oxide contents less than 5%. 2 Method Summary
UDC549.761.3
GB 9018.4--88
Adjusted to: HG2Ps&-188
The sample is melted with sodium carbonate-sodium hydroxide to convert calcium and magnesium into carbonate and hydroxide-separate sulfate ions, and the precipitate is dissolved with hydrochloric acid. Strontium chloride was added to eliminate the interference of coexisting ions. The absorbance of calcium and magnesium was measured in an atomic absorption spectrometer with an air-acetylene flame in a 2% hydrochloric acid medium, and their contents were calculated using the standard curve method. 3 Reagents and solutions
Anhydrous sodium carbonate (CB63977);
Sodium carbonate: 5% solution:
3.3 Sodium hydroxide (GB629-81):
3.4 Sodium peroxide:
3.5 = Ethanolamine: 1+4 solution;
3.6 Sodium carbonate-sodium hydroxide washing solution: 1% each mixed; 3.7 Hydrochloric acid (GB622-77): 1-1 solution;
3.8 Hydrochloric acid: 1-5 solution;
3.9 Hydrochloric acid: 1+9 solution:
3.10 Strontium chloride (SrC16H0) (Shanghai Q/HG221085-84): 10% solution. Weigh 168g of strontium chloride, add 300mL of water to dissolve it in warm water, cool it, and dilute it with water to! 000mL, shake (filter if necessary); 3.11 Potassium chloride (GB646-77); 1% solution; 3-12
Calcium carbonate (reference reagent),
3.13 Magnesium oxide (high purity reagent);
3.14 Calcium oxide standard solution: 200mg/l, weigh 1.7848g pre-dried calcium carbonate (3.12) in a 250mL beaker, add 20mL water, add hydrochloric acid (3.7) dropwise until completely dissolved, then add 10mL in excess, heat to boil, remove carbon dioxide, cool to room temperature, transfer to a 1 000mL volumetric flask, dilute with water to the mark, and shake. Pipette 100.0mL of the above solution into a 5DUmL volumetric flask, dilute with water to the mark, and shake well. This solution contains 200mg of calcium oxide per milliliter.
3.15 Magnesium oxide standard solution: 100mg/L. Weigh 1.0000g of magnesium oxide (3.1.3) previously burned at 800℃ to constant weight and place it in a 250mL beaker, add a little water, add 20mL hydrochloric acid (3.7), and heat until completely dissolved. Cool to room temperature, transfer to a 0.10mL container, dilute to the mark with water, shake, and take 100.0mL of the above solution in a 1 000mL container, dilute to the mark with water, and shake. This solution contains 100 μ ammonia magnesium.
4 Instruments and working parameters
4.1 Original absorption spectrometer
It is equipped with an air-acetylene fast burner device. The minimum sensitivity of the instrument should at least make the absorbance of the highest concentration standard solution in the standard series of solutions to be 0.3.
4.2 Working parameters
Wavelength, calcium - 122.7nm, chopsticks - 285.2nm. Other variable parts should adjust the instrument to the best working state. 5 Sample
The sample passes through a 0.075mm sieve (GB600985), is dried at 105~110r to constant weight, and is placed in a desiccator to cool to room temperature. 6 Analysis steps
6.1 Weigh the sample according to the table (weigh to 0.00 g) Place 3% anhydrous sodium carbonate (3.1) in a silver crucible, mix carefully, add a little sodium peroxide (3.4), 3% hydroxide (3.3), cover with a lid (leave a gap), put the crucible in a furnace, slowly raise the temperature to 50°C, stay for 10 minutes, continue to raise the temperature to 700-750%, keep for 30-40 minutes, take out and cool. Place the glass in a 250ml beaker containing 100mL of carbonic acid solution (3.2), add 15ml of trisodium iodide (3.3), cover with a lid (leave a gap), put the crucible in a furnace, slowly raise the temperature to 50°C, stay for 10 minutes, continue to raise the temperature to 700-750%, keep for 30-40 minutes, take out and cool. Avoid ethanol (3.5), add 1.5mL strontium chloride solution (3.10) to the blank test solution. Cover the surface III and heat on the hot plate (slightly boil 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-sodium hydroxide washing solution (3.6) 4~~5 times, and precipitate more than 12 times (wash until there is no sulfate). Table
Expected life
0. 15 -~ 0. 7
2>0. 7+-3. 5
2-3. 8~-5
0. 15 - 0. 3
>0. 3 --1. 5
> 1. 6 ~-5
Weigh the sample
Absorb the maximum test solution
Donate "sample mass
Add hydrochloric acid
(3.7) body
6.2 Cover the funnel with surface III, dissolve the sediment on the filter paper in 15mL hydrochloric acid (3.8) in batches, and wash the filter paper with hot water containing a few drops of hydrochloric acid (3.8). Dilute the solution with water to 100,㎡L, and boil for 3~4 minutes to drive out all carbon dioxide. Transfer the cold portion into a 200 mL volumetric flask (If the content of calcium oxide and magnesium oxide is greater than 0.15%, dilute with water to the mark, shake the spoon, and pipette a fixed volume of test solution D into a 200 mL volumetric flask according to the table). Add hydrochloric acid (3.7) according to Table 1. Add 10 ml of chlorinated liquid (3.10), 8 ml. Potassium chloride solution (3.11), dilute with water to the scale, shake the hook. 6.4 Adjust the wavelength, calcium 422.7nm, magnesium 285.2nm, according to the instrument manual, adjust the instrument's maximum parameters, and measure the absorbance respectively. The absorbance of the test liquid minus the absorbance of the blank test liquid is the net absorbance of the test liquid. At the same time, perform a blank test.
Drawing of the standard curve
GB.9018.4www.bzxz.net
Use a microburette to measure 0.00, 1.00, 2.00, 4.00, 6.00, 8.00, 10.00mL of calcium oxide standard solution (3.14), and place them in 7 200mL dissolving bottles respectively. Then use a microburette to measure the same volume of magnesium oxide standard solution (3.15) and place it in the above 200 mL volumetric bottles accordingly, add 8 mL hydrochloric acid (3.7), the following analysis is carried out according to step 6: 3.6. 4. The absorbance of the standard series solution minus the absorbance of the reagent blank is the net absorbance of the standard series solution. The standard curve is drawn with the micrograms of calcium hydride or magnesium oxide contained in each milliliter of standard solution as the horizontal axis and the corresponding net absorbance as the vertical axis:
Jiang; The preparation of the calcium bond standard series solution may vary depending on the instrument. For highly sensitive instruments, a more dilute standard solution can be used. 8 Calculation of analysis results
8.1 The white content of sodium hydroxide (X:) is calculated using formula (1): X,-m.×200 x 10-
Where:,---The concentration of calcium oxide is obtained from the standard curve using the net absorbance of the test solution, d/mL; the absorbed test solution is equivalent to the mass of the sample, B, 8.2 The percentage content of magnesium oxide (X,) is calculated using formula (2): X-heat × 200× 10
Where: ,
9Tolerance difference
Use the net absorbance of the test solution to obtain the concentration of magnesium oxide from the standard curve, ug/mL; the test solution absorbed is equivalent to the mass of the sample,. The difference between the results of the test in a laboratory case should be less than the values shown in Table 2 and Table 3. Table 2
Additional notes:
.0. 2D
0. 20 ~-1. 00
21. 00 -~ 5. 00
0. 20～[. 00
21.0-~5.00
This standard is under the jurisdiction of the Chemical Industry and Mining Design Institute of the Ministry of Chemical Industry. This standard is under the jurisdiction of the Chemical Industry and Mining Design Institute of the Ministry of Chemical Industry. The main drafters of this standard are Xu Xiulan, Wang Heping and Gu Lihua. 12
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