## 1 Introduction  
Ammonium nitrate-fuel oil (ANFO) is a class of energetic materials (EMs) that has found extensive use in blasting, particularly for mining purposes, and also in civilian excavations, demolitions and tunnel construction [1]. The main advantages of ANFO are the relatively low cost of its components and the ability to prepare the EM on site. It is also important to note that the \"fuel oil\" phase does not necessarily require petrol-based fuel oils and can be replaced by liquid waste products, such as spent oils, organic chemicals [2, 3], or even by solid organic fuels, such as wood meal, rape seed or flour [4].  
The main drawbacks of ANFO are its susceptibility to water, high critical diameter and relatively low performance (typically described using velocity of detonation and detonation pressure) [5]. This has sparked significant research interest in ameliorating these drawbacks while maintaining the advantages of ANFO, particularly its low unit cost. Works undertaking this goal typically focus on the introduction of a variety of additives, either to ANFO or to its components (ammonium nitrate and fuel oil) [6, 7]. Simultaneously,as the issues of greenhouse gas (GHG) emissions and energy consumption have became more relevant in recent decades, the focus of research efforts shifted to also include these issues [8].  
Cellulose nitrate, commonly referred to as \"nitrocellulose\" (NC), is an energetic material that can also act as an energetic binder and has found diverse industrial applications [9,10]. Recently, microstructured NC (MNC) [11,12] has attracted significant research attention, including our initial study on the viability of using it as an additive to non-ideal EMs. The preparation method is essentially the esterification of a microcrystalline cellulose with nitric acid, reflecting the traditional process for producing NC.  
An important discovery regarding MNC is its ability to coat ammonium nitrate (AN) [13], producing core-shell structures. The use of NC-coated AN in the place of porous AN prills for preparing ANFO-type EMs would be expected to increase initiation sensitivity, reaction zone energy and the amount of gases produced during detonation. These changes would be expected to result in ANFO exhibiting a lower critical diameter, higher velocity of detonation (VoD) and higher detonation pressure compared to traditional ANFO.  
In this work, we have aimed to explore the preparation of MNC, the process for coating AN, the preparation of ANFO from NC-modified AN and the sensitivity and combustion properties of the resultant ANFO formulations. In terms of synthesis, the effect of substituting the traditional HNO\({}_{3}\)/H\({}_{2}\)SO\({}_{4}\) esterification mixture with in situ-produced nitric acid (using a KNO\({}_{3}\)/H\({}_{2}\)SO\({}_{4}\)) mixture was investigated. The two reagent systems were employed both for traditional cellulose (yielding NC) and for microcrystalline cellulose (yielding MNC). The four resultant samples were used to coat AN and to produce ANFO formulations. Both NC/MNC-coated AN and the resultant ANFO formulations were investigated in terms of structure and composition by Raman spectroscopy and scanning electron microscopy (SEM). The sensitivity parameters and thermal features of these samples have also been studied.