Thermal orthophosphoric acid
Chemical Formula: H₃PO₄
- Grade A – Food-grade
- Grade B – Technical-grade
- Standard: GOST 10678-2019
Applications:
Used in the production of fertilizers, synthetic detergents, medicine, photography, metalworking, textile, oil, glass, ceramics, and food industries.
Characteristics and Indicators:
| Parameter Name | Standard for Grades A and B |
|---|---|
| 1. Appearance | A: Colorless, transparent liquid in a 15–20 mm layer against a white background. B: Colorless or slightly yellowish liquid in a 15–20 mm layer against a white background. |
| 2. Mass fraction of orthophosphoric acid (H₃PO₄), %, not less than | 73% |
| 3. Mass fraction of chlorides, %, not more than | A: 0.005 / B: 0.01 |
| 4. Mass fraction of sulfates, %, not more than | A: 0.01 / B: 0.015 |
| 5. Mass fraction of nitrates, %, not more than | A: 0.0003 / B: 0.0005 |
| 6. Mass fraction of iron, %, not more than | A: 0.002 / B: 0.01 |
| 7. Mass fraction of heavy metals (Pb), %, not more than | A: 0.0005 / B: 0.002 |
| 8. Mass fraction of arsenic, %, not more than | A: 0.0003 / B: 0.006 |
| 9. Mass fraction of reducing substances (as H₃PO₃), %, not more than | A: 0.1 / B: 0.2 |
| 10. Presence of metaphosphoric acid (HPO₃) | Passes the test |
| 11. Mass fraction of suspended particles, %, not more than | Passes the test |
| 12. Presence of yellow phosphorus (P₄) | A: Passes the test / B: Not standardized |
| 13. Mass fraction of fluorine (F), %, not more than | A: 0.001 / B: Not standardized |
| 14. Mass fraction of cadmium (Cd), %, not more than | A: 0.0001 / B: Not standardized |
Additional Information:
- Grade B orthophosphoric acid can be supplied with a mass fraction of orthophosphoric acid from 78% to 80% upon customer request.
- Indicators 3, 4, 5, 7, and 12 for Grade B are determined upon customer request.
- When used for fertilizer production, indicators 3 to 12 are not determined for Grade B.
- For consumer goods production, Grade B can be supplied with an H₃PO₄ mass fraction of at least 43%, subject to agreement with the customer.
- The mass fraction of reducing substances in first-grade phosphoric acid is standardized only for products used in the manufacture of technical salts and feed phosphates.
- In Grade B orthophosphoric acid used for feed phosphate production, the fluorine content must not exceed 0.1%; for chemical fiber production, the reducing substances content must not exceed 0.1%.
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