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Experimental Insight into the Catalytic Mechanism of MFe2O4 (M = Ni, Zn and Co) on the Thermal Decomposition of TKX-50

Hou Xiaoting, Zhang Ming, Zhao Fengqi, Yang Yanjing, An Ting, Li Hui, Pan Qing, Wang Xiaohong, Zhang Kun

Central European Journal of Energetic Materials

2021

Vol. 18, no. 2

223--244

Synthesized dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate (TKX-50) owes its outstanding application prospects in the field of insensitive solid propellants not only to its high energetic performance but also to its low mechanical sensitivity. Based on the excellent catalytic activity of bimetallic iron oxides for the thermal decomposition of TKX-50, the catalytic mechanism of bimetallic iron oxides (NiFe2O4, ZnFe2O4 and CoFe2O4) for TKX-50 pyrolysis has been explored. For this study, the decomposition process of TKX-50, before and after mixing with the bimetallic iron oxides NiFe2O4, ZnFe2O4 and CoFe2O4 was monitored by in-situ FTIR and gas-phase MS-FTIR instruments. Of the different catalysts, ZnFe2O4 gave the best result for reducing the initial decomposition temperature of TKX-50. Additionally, the activation energy of functional group cleavage of TKX-50, before and after mixing with ZnFe2O4, was also calculated for mechanism analysis from the results of the in-situ FTIR measurements. The results showed that the condensate and the gas-phase decomposition products of TKX-50 remained unchanged after mixing with different catalysts, while the activation energy of tetrazole ring cleavage was significantly reduced. The results of this study will be helpful for the rational design of insensitive solid propellant formulations containing TKX-50, and for understanding the pyrolysis mechanisms of TKX-50 before and after mixing with the efficient catalyst ZnFe2O4.

Effect of grinding media on the flotation behavior of fluorite using sodium oleate as a collector

Yao Wei, Li Maolin, Zhang Ming, Qian Gongming, Cui Rui, Ning Jiangfeng

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 3

556--565

Grinding, an essential procedure before flotation, to some extent, determines the flotation behavior of minerals. In this study, the effect of grinding media on the flotation behavior of fluorite using sodium oleate (NaOl) as a collector was investigated via micro-flotation experiments, zeta potential measurements, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses. The results indicated that, compared with the fluorite particles ground by ceramic media, the ones ground by cast iron media adsorbed less NaOl, resulting in lower flotation recovery. The lower flotation recovery of fluorite particles ground by cast iron media resulted from the coating of the hydrophilic Fe precipitates generated in the grinding, including Fe(0), Fe(OH)2, and Fe(OH)3on their surfaces. These Fe precipitates may cover the Ca active sites and increase the hydration membrane which can inhibit the further NaOl adsorption. This research reveals the effect of grinding media on the flotation behavior of fluorite and guides for media selection in disposing of fluorite ore.