Regular inspections of graphite petroleum coke during storage should focus on its physical condition, purity, and performance stability, with a particular focus on key indicators that may affect its use. The following are the key indicators:
I. Physical Condition Indicators
1. Agglomeration and Particle Size Change
- Inspection Content: Observe for lumps and compaction (especially for fine-grained products), as well as any abnormal changes in particle size due to compression or friction (such as an increase in fine powder or crushing of coarse particles).
- Impact: Agglomeration can cause transportation difficulties, and abnormal particle size may alter the reactivity, conductivity, and other properties of the graphite petroleum coke.
2. Moisture Content
- Inspection Method: Determine the moisture content by drying a sample (at 105°C to constant weight), or visually inspect the material for moisture and signs of moisture on the surface.
- Standard: Generally, a moisture content of ≤5% is required (depending on the intended use; higher-end applications may require lower values). Materials exceeding this limit must be dried before use.
II. Purity and Contamination Indicators
1. Impurity Contamination
- Inspection Details: Visually inspect the GPC for impurities such as oil, dust, metal debris, and acid and alkali residues.
For products requiring high purity (such as batteries), sample the GPC for excessive sulfur, nitrogen, and heavy metal content (chemical analysis or spectroscopy can be used).
- Impact: Impurities can reduce the purity of the GPC, especially in high-end metallurgy and electronic materials, potentially causing substandard product performance.
2. Corrosive Substance Adhesion
- Inspection Details: Observe the surface of the graphite petroleum coke for unusual color (such as yellowing or greening, which may indicate acid or alkali corrosion) or a pungent odor upon contact.
- Impact: Acid or alkali contamination may introduce corrosive ions, affecting the chemical stability of the GPC.
III. Performance-Related Indicators
1. Loss on Ignition (Ash Content)
- Inspection Method: Take a sample and ignite it (burn at 850°C to constant weight) and determine the residual ash percentage.
- Significance: Ash content primarily comes from mineral impurities. Dust or soil contact during storage can cause an increase in ash content. Furthermore, if slow oxidation occurs, the loss on ignition may also fluctuate abnormally, indirectly reflecting the degree of oxidation in the graphite petroleum coke.
2. Volatile Content Changes
- Inspection Method: Volatile content is measured by high-temperature calcination (heating at 900°C in an airtight container).
- Significance: Volatile content should be stable under normal storage. A significant decrease may indicate volatilization of lightweight components due to prolonged high temperatures, affecting GPC reactivity.
IV. Storage Environment Related Inspections
1. Storage Area Condition
Check the warehouse's ventilation and moisture-proofing facilities for proper operation (e.g., roof leaks, floor moisture).
Check the proximity of corrosive gases, open flames, or heat sources, and ensure that fire-fighting equipment is effective. 2. Recommended 2.Inspection Frequency
For normal storage environments: Check the physical and environmental conditions monthly, and sample and test key indicators such as moisture and ash content every three months.
For high-humidity or dusty environments: Check the physical condition every two weeks, and test for moisture and impurities monthly.
Regular monitoring of these indicators can promptly identify risks of graphite petroleum coke deterioration or contamination, ensuring it continues to meet production requirements during use.
