Chemical changes and the mechanisms in the sintering process of sea silt

M Li, X Cong
2017 Bulgarian Chemical Communications   unpublished
When sea silt that contains more soluble salt is used for the sintering of building materials, its adverse impact is a widespread concern. Lianyungang sea silt in Jiangsu Province is taken as an example. The changes of weight and heat, soluble salt and chlorine content in the sintering process are studied by laboratory experiments. The results show that the ion content of chlorine, sodium and sulfate is higher in the sea silt, the content of SO4 2-reaches a peak of 18‰ at 500 ℃, less than 4‰
more » ... ℃, less than 4‰ after 1000 ℃; the content of Na + decreases dramatically above 600 ℃, but remains 0.1 ‰ after 1000 ℃; the content of Cl-decreases sharply above 600 ℃ and is almost zero at 900 ℃. The XRF (X-ray fluorescence diffraction) test of sintering sea silt at 1000 ℃ shows that chlorine has disappeared and does not exists in a crystalline and glassy ionic state; the possible mechanism of sintering sea silt is dechlorination such that sodium chloride melts to a volatile solution at 800 ℃, the sodium chloride gas reacts with the water vapor, carbon or carbon dioxide to yield hydrogen chloride. In this study, the quantitative change of the soluble salt in the sea silt is proved by the change of the sintering temperature. The content of the soluble salt is very low when the sintering temperature is above 1000 ℃, which can eliminate the concerns for the sintering materials of sea silt. The transfer and transformation process of sodium chloride was revealed, which suggests that the tail gas treatment should be strengthened in the production of sintering building materials.