Natural Graphite Laboratory Testing Protocol

BASIC STUDY

1. Fixed Carbon (FC)

1A. Moisture

Sample 5 g

Temperature 105 ± 5°C

Duration 2 hours or until constant weight

Atmosphere Air

Result Moisture %, as received.

1B. Volatile Matter

Sample 1–2 g dried graphite

Temperature 900 ± 10°C

Duration 7 minutes

Atmosphere Inert / oxygen-limited

Result Volatile Matter %.

1C. Ash

Sample 1–2 g

Temperature 750–800°C

Duration 2–3 hours or until constant weight

Atmosphere Air

Result Ash %.

FC Calculation

FC (%) = 100 − Moisture − Volatile Matter − Ash

2. Particle Size Distribution (PSD)

2A. Flake Size Distribution — Sieve Analysis

Sample 50–100 g

Method Mechanical dry sieving

Sieves +35, +50, +80, +100, +150, +200 and −200 mesh

Duration 10–15 minutes

Result % in each size fraction.

2B. Laser Diffraction PSD

Sample 1–2 g

Method Laser diffraction

Measurement D10, D50, D90, D97 and D98

Dispersion Dry dispersion preferred; avoid aggressive sonication.

Result Complete PSD curve and particle size in µm.

3. Flake Morphology

Sample 0.5–1 g

Method Optical microscopy and SEM

Magnification 50×–500× optical; 100×–5,000× SEM

Procedure Examine representative flakes without crushing or excessive dispersion.

Result Flake shape, liberation, surface condition and attached impurities.

4. Flake Thickness and Aspect Ratio

Sample 0.1–0.5 g

Method SEM

Magnification 500×–5,000×

Procedure Measure at least 100 representative flakes.

Result Flake thickness, length, width and aspect ratio.

5. Bulk Density

Sample 50–100 g

Method Graduated-cylinder method

Procedure Pour graphite gently into a calibrated cylinder without tapping or vibration.

Result Bulk density, g/cm³.

6. Tap Density

Sample 50–100 g

Method Tapped-density apparatus

Procedure Tap approximately 250–500 times or until constant volume.

Result Tap density, g/cm³.

7. ICP-OES / ICP-MS — Trace Element Analysis

Sample 0.1–0.5 g

Method Appropriate validated digestion followed by ICP-OES/ICP-MS

Elements Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Si, Sn, Sr, Ti, V, W, Y, Zn, Zr, S, Cl and F.

Detection Preferably ≤1 ppm for critical elements when testing ≥99% graphite.

Result Individual elements in ppm, including detection limit/LOQ.

Note:

Laboratory must confirm that its validated ICP method can accurately measure S, Cl and F at the required concentrations or test separately.

8. X-Ray Diffraction (XRD)

Sample 1–2 g

Method Powder XRD

Radiation Cu Kα

Scan Range 10–80° 2θ

Step Size 0.02°

Result Graphite phase, d002 spacing, crystallinity and identification of crystalline mineral impurities.

9. Raman Spectroscopy

Sample 0.05–0.1 g

Method Raman spectroscopy

Laser 532 nm, low power

Range 100–3,200 cm⁻¹

Procedure Measurements at several locations on the sample.

Result D, G and 2D bands; ID/IG ratio; peak position and FWHM.

10. SEM-EDS

Sample 0.1–0.5 g

Method SEM with EDS

Magnification 100×–5,000×

Procedure Examine multiple representative areas.

Result Flake morphology and qualitative/semi-quantitative elemental distribution.

Advanced Study

11. True Density

Sample 1–5 g

Method Helium pycnometer

Temperature 20–25°C

Procedure Dry sample and perform repeated helium-displacement measurements until stable.

Result True density, g/cm³.

12. BET Specific Surface Area

Sample 0.5–2 g

Method Nitrogen adsorption — BET

Degassing 120°C for 2–4 hours

Measurement Approximately −196°C

Result BET surface area, m²/g.

13. Thermogravimetric Analysis (TGA)

Sample 10–30 mg

Atmosphere Nitrogen/inert gas

Heating Rate 10°C/min

Temperature Ambient to 1,000°C

Additional Air/oxygen test where required.

Result Moisture loss, volatile matter, thermal stability and oxidation behaviour.

14. Magnetic Impurities

Sample 10–50 g

Method Magnetic separation followed by weighing and ICP analysis.

Procedure Pass dried graphite through a calibrated magnetic separator at controlled magnetic intensity.

Result Magnetic fraction %, Fe, Ni, Cr and other magnetic impurities.

15. Mineralogical Analysis

Sample 5–10 g

Method XRD + SEM-EDS; automated mineralogy where available.

Procedure Identify and quantify major mineral phases.

Result Quartz, mica, feldspar, clay minerals, iron minerals, carbonates and other gangue minerals.

16. XPS — Surface Chemistry

Sample 0.1–0.5 g

Method X-Ray Photoelectron Spectroscopy

Procedure Analyse graphite surface with minimum sample preparation.

Result Surface elemental composition and chemical bonding states, particularly carbon and oxygen.

17. Electrical Conductivity / Resistivity

Sample 5–20 g

Method Four-point probe or suitable powder-resistivity method

Procedure Prepare specimen at controlled compaction pressure/density and measure electrical resistance.

Result Electrical resistivity, Ω•cm, and/or conductivity, S/cm.

18. Thermal Conductivity

Sample According to instrument requirement, typically 10–50 g

Method Laser flash analysis or suitable thermal-conductivity method

Temperature 25°C and elevated temperatures where required

Procedure Prepare specimen at controlled density and measure thermal diffusivity/conductivity.

Result Thermal conductivity, W/m•K.