GB/T 18114.1-2010 Chemical analysis methods of rare earth concentrates - Part 1: Determination of total rare earth oxide contents - Gravimetry
1 Scope
This part of GB/T 18114 specifies the determination method of total rare earth oxide contents in the rare earth concentrates.
This part is applicable to the determination of total rare earth oxide contents in the rare earth concentrates. Determination range: 20.00%-80.00%.
2 Principle
The specimen is melted and decomposed using sodium hydroxide-sodium peroxide to separate silicon and aluminum. The precipitate is dissolved using hydrochloric acid, while hydrofluoric acid is employed to separate iron, manganese, titanium, niobium, tantalum, nickel, etc. The silicon is removed through the process of perchloric acid fuming, and calcium and magnesium are precipitated and separated using ammonium hydroxide. Rare earth and thorium are precipitated using oxalic acid with pH 1.8-2.0 and then be ignited to constant weight. The thorium oxide content in the precipitate is determined, and the total rare earth oxide contents are obtained by deduct the thorium oxide content.
3 Reagents and materials
3.1 Sodium hydroxide.
3.2 Sodium peroxide.
3.3 Ammonium chloride.
3.4 Hhydrofluoric acid (ρ=1.13 g/mL).
3.5 Perchloric acid (ρ=1.67 g/mL).
3.6 Hydrogen peroxide (30%).
3.7 Nitric acid (ρ=1.42 g/mL).
3.8 Ammonium hydroxide (1+1).
3.9 Hydrochloric acid (1+1).
3.10 Hydrochloric acid cleansing solution: 100 mL of water contains 4 mL of hydrochloric acid (3.9).
3.11 Sodium hydroxide cleansing solution (20 g/L).
3.12 Hydrochloric acid-hydrofluoric acid cleansing solution (2+96).
3.13 Ammonium chloride-ammonium hydroxide cleansing solution: 100 mL of water contains 2 g of ammonium chloride and 2 mL of ammonium hydroxide.
3.14 Oxalic acid solution (100 g/L).
3.15 Methylphenol red ethanol solution (2 g/L): Weigh 0.2 g of methyl red and dissolve it in 100 mL of ethanol solution (1+1).
3.16 Oxalic acid cleansing solution: 100 mL of the solution contains 1 g of oxalic acid, 1 g of ammonium oxalate, and 1 mL of anhydrous ethanol.
3.17 Thorium oxide standard stock solution: Accurately weigh 0.1000 g of thorium dioxide [ω(ThO2) ≥ 99.95%, dried at 110°C] and place it in a 250-mL beaker, add 10 mL of hydrochloric acid (ρ=1.19 g/mL) and 0.5 mL of hydrofluoric acid (3.4), heat to dissolve, and then add 2 mL of perchloric acid (3.5) and evaporate until white fumes occur and a wet salt condition is formed, cool it and dissolve with 5 mL of hydrochloric acid (3.9) and then dilute it to the scale with hydrochloric acid (1+9) in a 100-mL volumetric flask, mix well. 1 mL of this solution contains 1 mg of thorium oxide.
3.18 Argon: [ω(Ar)≥ 99.99%].
4 Apparatus
4.1 Plasma optical emission spectrometer: With a resolution < 0.006 nm (at 200 nm).
4.2 Light source: Argon plasma light source.
5 Specimen
5.1 The particle size of the specimen shall be ground until it passes through a 0.074-mm sieve.
5.2 The specimens shall be dried at 105 °C to 110 °C for 2 h, and then cooled to room temperature in a desiccator.
Foreword i
1 Scope
2 Principle
3 Reagents and materials
4 Apparatus
5 Specimen
6 Analytical steps
7 Calculation and expression of analysis results
8 Precision
9 Quality assurance and control
