HG 2958.9-1988 Determination of aluminum content in celestite ore EDTA volumetric method
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Chemical Industry Standard of the People's Republic of China
Determination of aluminum content in celestite ore
EDTA volumetric method
Celestite ores-Determination of aluminiuncontentEDTAvolunetric method Subject content and scope of application
This standard specifies the determination of aluminum content in celestite ore by EDTA volumetric method. This standard is applicable to celestite ore products with an alumina content greater than 0.5%. 2 Method summary
UDC549.761.3
:543.06
HG/T2958.9-1988(1997)
Replaces GB9018.9-88
The sample is melted with alkali, leached with water, and aluminum is separated as soluble metaaluminate. Then, excess EDTA solution is added. In a solution of pH~5.8, with xylenol orange as indicator, the excess EDTA is titrated with zinc standard solution. Sodium fluoride is added to displace the EDTA complexed with aluminum, and then the solution is titrated with zinc standard solution.
3 Reagents and solutions
3.1 Sodium hydroxide (GB629-81);
3.2 Sodium peroxide;
3.3 Trisodium phosphate (HG3~1292-80);
3.4 Hydrochloric acid: (GB622-77): 1+1 solution; 3.5 Hydrochloric acid: 1+9 solution;
3.6 Ammonia water (GB631-77): 1+1 solution; Glacial acetic acid: (GB676-78);
3.8 Glacial acetic acid: 1+1 solution;bZxz.net
3.9 Anhydrous ethanol (GB678-78);
Sodium acetate (CH,COONa·3H,O) (GB693-77);3.10
Ammonium chloride (GB658-77);
Congo red test paper;
Sodium fluoride (GB1264-77): 4% solution. Weigh 4g of sodium fluoride and dissolve it in 100ml of water, then add glacial acetic acid (3.8) dropwise until the pH of the solution is 5.5~6. Store in plastic bottles;
3.14 Disodium ethylenediaminetetraacetate (EDTA) (GB1401-78): C (EDTA) = 0.04 mol/L solution;3.15 Zinc acetate (HG3-1098-77);
3.16 Zinc acetate solution: c (Zn (CH, CO0) 2? 2H, O) = 0.04 mol/L. Weigh 4.4g zinc acetate (3.15) and dissolve it in 500ml water, add glacial acetic acid (3.8) dropwise until the solution pH is 5.5~6;3.17 Xylenol orange: 0.5% solution. Weigh 0.5g of xylenol orange and dissolve it in 50ml of water, add 50ml of anhydrous ethanol (3.9), shake the spoon, and put it in a brown bottle;
Ministry of Chemical Industry of the People's Republic of China. Approved on March 21, 198868
Implementation on December 1, 1988
HG/T2958.9-1988 (1997)
3.18 Acetic acid-sodium acetate buffer solution (pH~5.8): Weigh 200g of sodium acetate (3.10) and dissolve it in 500ml of water, add 9ml of glacial acetic acid (3.7), dilute with water to 1000ml, and shake well; No. Al, O,) = 0.01200mol/L. Weigh 0.3238g of metallic aluminum with surface oxide removed 3.19 Alumina standard solution: c (-
(99.90%) in a beaker, add 20ml hydrochloric acid (3.4), heat on a hot plate until completely dissolved, remove, cool, transfer to a 1000ml volumetric flask, dilute to scale with water, and shake well; 3.20 Zinc acetate standard solution: c (Zn (CHC00) 22HO) = 0.012mol/L; 3.20.1 Preparation: Weigh 2.64g zinc acetate (3.15) and dissolve in 200ml water, add 2ml glacial acetic acid (3.7), dilute to 1000ml with water, and shake well.
3.20.2 Calibration: Pipette 20.00ml of alumina standard solution (3.19) In a 250ml beaker, proceed as per analysis steps 5.2 and 5.3.
3.20.3 Calculation of concentration: The concentration (c) of zinc acetate standard solution is calculated according to formula (1). C
Wherein: Ci is the concentration of alumina standard solution, mol/L; V is the volume of alumina standard solution absorbed, mol; Giy
V is the volume of zinc acetate standard solution consumed during titration, ml. 4 Sample
The sample is passed through a 0.075mm sieve (GB6003-85), dried at 105-110℃ to constant weight, and placed in a desiccator to cool to room temperature. 5 Analysis steps
5.1 Weigh 0.20.3g of sample (accurate to 0.0002g), add 3g Sodium hydroxide (3.1), 0.5g trisodium phosphate (3.3), a little sodium peroxide (3.2), cover the crucible (leave a gap), place the crucible in a muffle furnace, raise the temperature from low temperature to 300℃, stay for 10 minutes, continue to rise to 700-750℃, keep for 30 minutes, take out and cool. Place the crucible in a 250ml polytetrafluoroethylene beaker, soak it with 50ml hot water, and after the molten block falls off, wash it with hot water and a small amount of hydrochloric acid (3.5), heat and boil for 2 minutes. After cooling, transfer it to a 100ml volumetric flask, dilute it to the scale with water, and shake it well. Let it stand for a while, and dry filter it with double-layer medium-speed filter paper. Pipette 50.00ml of filtrate into a 250ml beaker.
5.2 Add 10ml EDTA solution (3.14), use Dilute to 100ml with water. Add 8-10ml hydrochloric acid (3.4), put in a small piece of Congo red test paper, and add ammonia water (3.6) to neutralize until the Congo red test paper turns red. Add 10ml sodium acetate buffer solution (3.18), heat and boil for 23min, remove and cool to warm, add 2-3 drops of xylenol orange indicator solution (3.17), add zinc acetate solution (3.16) drop by drop until it is close to the end point, and then continue to titrate with zinc acetate standard solution (3.20) until the solution turns purple-red (ignore the reading). 5.3 Add 10ml sodium fluoride solution (3.13), boil for 2-3min, remove and cool to warm, add 1-2 drops of xylenol orange indicator solution (3.17), and titrate with zinc acetate standard solution (3.20) until the solution turns purple-red as the end point. Perform a blank test at the same time.
6 Calculation of analysis results
The percentage content (X) of aluminum oxide (Al,O) is calculated according to formula (2): X=c(Vi-Vo)×0.05098
m×100
Wherein: V. is the volume of zinc acetate standard solution consumed by titrating the blank test solution, ml; V. is the volume of zinc acetate standard solution consumed by titrating the test solution, ml; (2)
HG/T 2958.9-1988 (1997)
is the concentration of zinc acetate standard solution, mol; is the mass of the sample, g.
0.05098—1.00ml zinc acetate standard solution lc [Zn (CHC00), 2H,O] = 1.000mol/L is equivalent to the mass of aluminum oxide, g.
7 Allowable difference
The difference between the results of the same laboratory should be less than the value shown in the following table. Alumina
0.50~1.00
>1.00~5.00
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 Min Yuyao and Gu Lihua. 70
Allowable difference
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