Modification of ADP extinguishing powder by siliconization in spray drying--颗粒学报PARTICUOLOGY

Zhang, X., Shen, Z., Cai, C., Yu, X., Du, J., Xing, Y., & Ma, S. (2012). Modification of ADP extinguishing powder by siliconization in spray drying. Particuology, 10(4), 480–486. https://doi.org/10.1016/j.partic.2011.11.001

Modification of ADP extinguishing powder by siliconization in spray drying

Xiaojing Zhang ^a *, Zhigang Shen ^a, Chujiang Cai ^a, Xiaozheng Yu^a^b, Jun Du ^c, Yushan Xing ^a, Shulin Ma ^a

a Beijing Key Laboratory for Powder Technology Research and Development, Beijing University of Aeronautics and Astronautics, Beijing 100191, China
b Science School, Beijing University of Civil Engineering and Architecture, Beijing 100044, China
c Beijing Institute of Structure and Environment Engineering, Beijing 100076, China

10.1016/j.partic.2011.11.001

Volume 10, Issue 4, August 2012, Pages 480-486

Received 13 December 2010, Revised 14 October 2011, Accepted 8 November 2011, Available online 20 January 2012.

E-mail: zhangxiaojing@buaa.edu.cn

Highlights

► An activation index was introduced as a measure of particle surface hydrophobicity.

► According to activation index measurements and characterization of modified ADP powder, optimum modification conditions were determined as MHSO-to-ADP mass ratio 3%, exit air temperature below 100 °C and low humidity of inlet air for spray drying.

Abstract

Superfine spherical fire-extinguishing powder, ammonium dihydrogen phosphate (ADP, NH₄H₂PO₄), was prepared by spray drying and modified in situ with methyl hydrogen silicone oil (MHSO) emulsion and the fluorinated surfactant FK-510. The influences of the MHSO mass ratio on the hydrophobicity, surface composition, surface morphology, dispersion and particle-size distribution of the NH₄H₂PO₄ were studied, and the influence of the drying air temperature on the decomposition of the NH₄H₂PO₄ was also researched. The results indicate that the MHSO and FK-510 congregate on the particle surfaces and then form a hydrophobic shell. This shell improves the particle hydrophobicity and leads to a fine dispersion of the particles. During the process of preparing the precursor solution, 3 wt% (based on the weight of NH₄H₂PO₄) was chosen as the optimum value of the MHSO mass ratio. During the spray drying, a low absolute humidity of the air should be maintained, and it is very important to keep the exit-air temperature below 100 °C to avoid decomposition.

Graphical abstract

Keywords

Methyl hydrogen silicone oil (MHSO); Ammonium dihydrogen phosphate (ADP); Fire-extinguishing powder; Spray drying; Drying air temperature; Agglomeration

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