The Influence of Microstructured Charcoal Additive on ANFO’s Properties

Andrzej Biessikirski,Michał Dworzak,Łukasz Kuterasiński,Michał Twardosz,Mateusz Pytlik,Bogna Daria Napruszewska,Suzana Gotovac Atlagić,Dagmara Nowak-Senderowska

doi:10.3390/en14144354

Abstract

The verification of the blasting parameters of Ammonium Nitrate Fuel Oil (ANFO) with the addition of microstructured charcoal (MC) produced by destructive wood distillation was performed. Additional investigation of specific surface and pore distribution by the nitrogen adsorption of the two granulations of MC was also carried out. High-resolution scanning electron microscopy was used for morphology evaluation and revealed smoothening of the initially developed external surface of carbon with intensive milling. In addition, the analysis of the thermal properties of the studied samples (TG/DSC) indicated that the size of the microstructured charcoal additives influenced the decomposition temperature of the prepared materials. The explosives containing microstructured charcoal grains of −90 μm underwent decomposition at lower temperatures in comparison with those containing higher sizes of microstructure charcoal grains (−1.18 mm), for which the decomposition temperature reached 292 °C. The obtained results of blasting parameters compared to the results derived from thermodynamic simulation showed the non-ideal character of the explosives (much lower values of blasting parameters than in established thermodynamic models). It was indicated that higher velocities of detonations (VOD) were obtained for non-ideal explosives where finer MC grains were added. Blasting tests confirmed that the studied type of MC can be applied as an additive to the ANFO.

Highlights

Ammonium nitrate fuel oil (ANFO) is a mixture of ammonium nitrate (V) (AN) with a fuel oil (FO) with a weight ratio which should ensure zero oxygen balance
The main difference between AN-F and ammonium nitrate (V) porous prill (AN-PP) is the lower density, higher retention, and higher absorption index (AN-PP is ca. 12–16% and AN-F ca. 8%) of AN-PP which can be explained by higher porosity and the presence of numerous surface deformations in AN-PP prills [1,2,3,4]
The aim of this work was to make an evaluation of the following blasting parameters: heat of explosion, velocity of detonation (VOD), and the post-blast oxides of non-ideal explosives based on two different assortments of microstructured charcoal (MC) powders

Summary

Introduction

Ammonium nitrate fuel oil (ANFO) is a mixture of ammonium nitrate (V) (AN) with a fuel oil (FO) with a weight ratio which should ensure zero oxygen balance. The weight ratio between AN and FO is 94.5:5.5, due to the possible modification in FO composition or the application of a different type of fuel oil, the weight ratio between oxygen and the fuel component can change slightly. It should be noted that various types of the oxygen component can be used. Ammonium nitrate (V) porous prill (AN-PP) is used as the oxygen component and this is recommended by a number of pieces of research [1,2,3]. Devices), the fertilizer grade of ammonium nitrate (V) (AN-F) is used. The main difference between AN-F and AN-PP is the lower density, higher retention, and higher absorption index (AN-PP is ca. 12–16% and AN-F ca. 8%) of AN-PP which can be explained by higher porosity and the presence of numerous surface deformations in AN-PP prills [1,2,3,4]

Objectives

Methods

Conclusion