The STPP powder is mainly used in the preparation of detergent slurry. Molecular structure of STPP is presented in two different forms called phase 1 and phase 2. The rate of composition of the STPP in phase 1 and phase 2 gives various rate of hydration. In general, for each technique of slurry preparation, there is a specific quality of STPP.
For modern installations of detergent, with fast and powerful mixers, the stpp high rate of hydration is recommended. It permits reduction time in the preparation of the slurry, saving energy in the heating and the drying of the slurry and a better quality of detergent powder.
For other installations, the STPP with low or middle rate of hydration is recommended; this prevents the formation of lumps during the slurry preparation, but requires a slower preparation time and an extra energy consumption.
| DESIGNATIONS | UNITS | ANALYSIS | SPECIFICATIONS | NORMS |
| Appearance | / | OK | Free flowing white powder Free from visible contaminants | / |
| P2O5-content as is | % | 56.06 | 56,00 Mini | ISO 3357/NFT 20486 |
| STPP-content as is | % | 94.12 | 94,00 Mini | ISO 3000/NFT 20492 |
| Phase I content | % | 40.4 | 20,0 55,0 | NFT 20496 |
| Water content (loss at 13S*C-4h) | % | 0.34 | 0,75 Maxi | ISO 2483/NFT 20401/P&G USP731 |
| Loss on ignition (500°C) | % | 0.18 | 0,70 Maxi | ISO R853/NFT 20484 |
| Water insoluble materials | % | 0.030 | 0,200 Maxi | ISO R850/NFT 20493 |
| Sodium sulfate content | % | 1.970 | 2,000 Maxi | Plasma Emission |
| Sodium chloride content | % | 0.3200 | 0,6000 Maxi | NFT 20495 |
| Colour values Whiteness | / | 95.78 | 90,00 Mini | Hunter Lab |
| Bulk density | g/l | 370 | 300-420 | ISO 697/NFT 73405 |
| Particle Size > 710 microns | % | 0.18 | 10,00 Maxi | ISO 2996/NFT 20485 |
| Particle Size < 180 microns | % | 14.80 | 15,00 Maxi | ISO 2996/NFT 20485 |
| pH (1% solution) | / | 9.58 | 9,30 – 10,00 | ISO R851/NFT 20494 |
| Trace metals Cr | ppm | 0.7 | 1,0 Maxi | Plasma Emission |
| Trace metals Co | ppm | <0.1 | 1,0 Maxi | Plasma Emission |
| Trace metals Ni | ppm | 0.9 | 1,0 Maxi | Plasma Emission |
| Trace metals Cu | ppm | <0.2 | 1,0 Maxi | Plasma Emission |
| Trace metals Cd | ppm | 0.4 | 1,0 Maxi | Plasma Emission |
| Trace metals Pb | ppm | <1.0 | 1,0 Maxi | Plasma Emission |
| Trace metals Hg | ppm | <0.5 | 1,0 Maxi | Plasma Emission |
| Trace metals As | ppm | <2.0 | 5,0 Maxi | Plasma Emission |
| Trace metals Mn | ppm | 1.1 | 5,0 Maxi | Plasma Emission |
| Trace metals Fe | ppm | 10 | 25 Maxi | Plasma Emission |
| Trace metals Mg+Ca | ppm | 172 | 300 Maxi | Plasma Emission |
Also high dense specification is available.
