Shenzhen Batian Ecological Engineering Co.

Shenzhen, China

Shenzhen Batian Ecological Engineering Co.

Shenzhen, China
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Wang H.,Taiyuan University of Technology | Li R.,Taiyuan University of Technology | Fan C.,Taiyuan University of Technology | Feng J.,Shenzhen Batian Ecological Engineering Co. | And 2 more authors.
Journal of Fluorine Chemistry | Year: 2015

Fluorine is a major pollutant in the conversion of phosphate rock to nitrophosphate fertilizer. In this paper, removal of fluoride in the nitrophosphate process was investigated. Fluoride ion-selective electrode and acid-base titration method were employed to determine the fluoride content and species in the actual acid digestion liquor. It was found that fluoride was present in two forms of H2SiF6 (0.78 wt% F-) and HF (0.10 wt% F-). Precipitation tests were performed both in pure fluoride solution (H2SiF6 + HF + H2O) and actual acid digestion liquor using KNO3 as precipitant. Influences of reaction time, temperature and KNO3 addition were studied. The precipitates obtained were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). Precipitation experiments revealed that the addition of KNO3 would remove the fluoride effectively, and the obtained precipitates were the high-purity K2SiF6. The maximum fluoride removal efficiency could reach 88.52% at 25 °C when 400% excess of KNO3 was added in the pure fluoride solution after 1 h. However, the fluoride removal efficiency reached only 70.22% in actual acid digestion liquor under the same experimental conditions. These obtained results are important and meaningful for the sustainable development of nitrophosphate fertilizer. © 2015 Elsevier B.V. All rights reserved.


Wang H.,Taiyuan University of Technology | Li R.,Taiyuan University of Technology | Fan C.,Taiyuan University of Technology | Feng J.,Shenzhen Batian Ecological Engineering Co. | And 2 more authors.
Journal of Fluorine Chemistry | Year: 2015

In this paper, the solubility values of potassium hexafluorosilicate (K2SiF6) were measured in phosphoric acid, nitric acid and mixed acidic aqueous solutions according to the different acidic concentrations and different temperatures of 25, 45, and 65°C. The influence of different nitrates on the solubility of K2SiF6 in mixed acidic aqueous solutions was also discussed. The results revealed that the solubility values of K2SiF6 increased with raising temperature, and were declining in phosphoric acid solution but were rising in nitric acid solution. The nitrates in acidic solutions have some influences on the solubility of K2SiF6. These obtained results would provide basic data for the fluorine removal from the production process of nitrophosphate fertilizer. © 2015 Elsevier B.V. All rights reserved.

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