YS/T 509.5-2008Methods for Chemical Analysis of Spodumene and Lepidolite Concentrates - Determination of ferric oxide content - O-phenanthroline photometric method and EDTA compleximetric method (English PDF)

6.3 Blank test

Conduct blank test with test material.

6.4 Determination

6.4.1 Place the test material (6.1) in a 30mL silver crucible. Add 3 drops of absolute ethanol (3.2) to moisten. Add 5g of potassium hydroxide (3.1). Put the lid on the crucible and leave a little gap. Remove the moisture on an electric stove. Place in 600°C~650°C high temperature furnace to melt for

10min~15min. Take out. Cool.

6.4.2 Use filter paper to wipe the outer wall of the crucible. Put it in a 250mL beaker. Add 100mL of hot water. Cover the watch glass. Leach the melt. Add

35mL of hydrochloric acid (3.3) from the mouth of the beaker at a time. Shake immediately to totally acidify the solution. Use hot water to wash out the crucible.

Boil the solution for 1min~2min. Cool to room temperature. Transfer into a

250mL volumetric flask. Use water to dilute to the graduation of scale. Mix well.

Let it stand. Pipette 25.00mL of supernatant. Place it in a 100mL volumetric flask.

6.4.3 Add 5mL of ascorbic acid solution (3.7). Mix well. Add 2 drops of p- nitrophenol ethanol solution (3.11). Use ammonium hydroxide (3.5) to neutralize until the solution just turns yellow. Then use hydrochloric acid (3.4) to neutralize until the yellow color just disappears. Add 20mL of buffer solution (3.8). Mix well. Add 2.5mL of o-phenanthroline ethanol solution (3.6). Use water to dilute to the graduation of scale. Mix well. Let it stand for 15min.

6.4.4 Move part of the solution (6.4.3) into a 2cm cuvette. Take the blank of the accompanying specimen as a reference. At a wavelength of 506nm of the spectrophotometer, measure its absorbance. Find the corresponding amount of ferric oxide from the working curve.

6.5 Drawing of working curve

6.5.1 Pipette 0mL, 1.00mL, 2.00mL, 5.00mL, 7.00mL, 10.00mL, 12.00mL and

15.00mL of ferric oxide standard solution (3.10). Respectively put in a set of

100mL volumetric flasks. Add 1mL of hydrochloric acid (3.3). The rest follows the steps in 6.4.3.

6.5.2 Transfer part of the solution (6.5.1) into a 2cm cuvette. Take the

accompanying reagent blank as a reference. At a wavelength of 506nm of the spectrophotometer, measure its absorbance. Use the amount of ferric oxide as the abscissa and absorbance as the ordinate to draw a working curve.

12.6 Ferric oxide standard solution: Weigh 0.5000g of ferric oxide (above 99.9%)

that has been pre-baked at 105°C~110°C for 2h and placed in a desiccator to cool to room temperature. Put it in a 250mL beaker. Add 30mL of hydrochloric acid (12.4). Cover the watch glass. Heat at low temperature to dissolve completely. Remove. Cool to room temperature. Transfer to 1000mL volumetric desiccator to cool to room temperature.

14.1 Test material

Weigh 0.50g of specimen, to the nearest of 0.0002g.

14.2 Number of determinations

Make parallel determinations of two test materials. Take the average value.

14.3 Blank test

Conduct blank test with test material.

14.4 Determination

14.4.1 Place the test material (14.1) in a 30mL silver crucible. Add 5 drops of absolute ethanol (12.3) to moisten. Add 5g of potassium hydroxide (12.1). Put the lid on the crucible and leave a little gap. Remove moisture on an electric stove. Place in 600°C~650°C high temperature furnace to melt for

10min~15min. Take out. Cool.

14.4.2 Use filter paper to wipe the outer wall of the crucible. Put it in a 250mL beaker. Cover the watch glass. Add 100mL of hot water from the mouth of the beaker. Leach the melt. Then add 35mL of hydrochloric acid (12.4) at a time.

Immediately shake to acidify the solution. Use hot water to wash out the crucible.

Boil the solution for 2min. Cool to room temperature.

14.4.3 Transfer the solution (14.4.2) into a 250mL volumetric flask. Use water

to dilute to the graduation of scale. Mix well. Let it stand.

14.4.4 Pipette 50.00mL of supernatant (14.4.3). Put it in a 300mL Erlenmeyer

flask. Add 0.1g of ammonium persulfate (12.2). Heat to slightly boil and keep it for 5min. Cool for a while. Add 6 drops of sulfosalicylic acid solution (12.8). Use ammonium hydroxide (12.5) to neutralize until the purple disappears and brownish red appears. Immediately use hydrochloric acid (12.4) to carefully neutralize until the purple color just appears and exceed by 4 drops. Control the temperature of the solution at about 60°C. Use EDTA standard solution (12.7) to slowly titrate until the purple color disappears as the end point.