204
A. E. Artyukhov et al.
3. The ordinary ammonium nitrate does not have sufficient porosity for successful
retention of the diesel fuel distillate inside the granule.
4. The ordinary ammonium nitrate has a certain number of pores, but their nature
is mechanical, not modifying. These are the pores that are obtained as a result
of the destruction of the granules (cracks, chips, caverns). Such pores are large
enough (10
−6 –10
−4 m), and it is difficult to hold the diesel fuel distillate (when
transporting ANFO to the blasting places, the diesel fuel distillate flows out of
the granule and ideally stays on the surface, at worst—leaves the surface of the
granule).
The production of PAN from the ordinary ammonium nitrate by the method of
humidification and heat treatment (the method is one of the most energy-efficient
and environmentally safe, which is proved in a number of works [4–6]) requires
special hydrodynamic and thermodynamic conditions, as well as rational selection
of the type and construction of the main technological equipment in granulation. The
main task of the technology to produce PAN from the ordinary ammonium nitrate
is to form a network of nanopores on the granule surface and in the surface layers,
keeping the strength of the core [7–9]. Vortex granulators are proposed as granulation
equipment in the works [10–13]. They have the following advantages:
– the possibility significantly to reduce the overall dimensions (in particular, the
height) of the workspace due to the variable height of the cross-sectional area and
the possibility of internal circulation of the seeding agent;
– control of the granules’ residence time in the workspace;
– the ability to control the motion of granules in the workspace;
– the possibility to create intensive turbulence in the workspace;
– universality (the ability to carry out granulation and drying processes in one
device);
– processability and ease of production;
– possibility of fast adjustment and change of constructive and technological
parameters if necessary.
The aim of this work is to study the thermodynamic conditions to form PAN
granules with nanoporous structure and to evaluate the influence of thermodynamic
parameters on the features of the nanopores structure.
2 Theoretical Principles of Thermodynamics Regarding
PAN Granules Drying
According to the previous studies in the field of PAN granule production [7, 9, 11],
thermodynamic and hydrodynamic conditions (temperature, gas velocity, time of
contact of the granules with hot gas (air) environment) are the main factors which
form the porous structure. In addition, having removed the bulk of the moisture and
A. E. Artyukhov et al.
3. The ordinary ammonium nitrate does not have sufficient porosity for successful
retention of the diesel fuel distillate inside the granule.
4. The ordinary ammonium nitrate has a certain number of pores, but their nature
is mechanical, not modifying. These are the pores that are obtained as a result
of the destruction of the granules (cracks, chips, caverns). Such pores are large
enough (10
−6 –10
−4 m), and it is difficult to hold the diesel fuel distillate (when
transporting ANFO to the blasting places, the diesel fuel distillate flows out of
the granule and ideally stays on the surface, at worst—leaves the surface of the
granule).
The production of PAN from the ordinary ammonium nitrate by the method of
humidification and heat treatment (the method is one of the most energy-efficient
and environmentally safe, which is proved in a number of works [4–6]) requires
special hydrodynamic and thermodynamic conditions, as well as rational selection
of the type and construction of the main technological equipment in granulation. The
main task of the technology to produce PAN from the ordinary ammonium nitrate
is to form a network of nanopores on the granule surface and in the surface layers,
keeping the strength of the core [7–9]. Vortex granulators are proposed as granulation
equipment in the works [10–13]. They have the following advantages:
– the possibility significantly to reduce the overall dimensions (in particular, the
height) of the workspace due to the variable height of the cross-sectional area and
the possibility of internal circulation of the seeding agent;
– control of the granules’ residence time in the workspace;
– the ability to control the motion of granules in the workspace;
– the possibility to create intensive turbulence in the workspace;
– universality (the ability to carry out granulation and drying processes in one
device);
– processability and ease of production;
– possibility of fast adjustment and change of constructive and technological
parameters if necessary.
The aim of this work is to study the thermodynamic conditions to form PAN
granules with nanoporous structure and to evaluate the influence of thermodynamic
parameters on the features of the nanopores structure.
2 Theoretical Principles of Thermodynamics Regarding
PAN Granules Drying
According to the previous studies in the field of PAN granule production [7, 9, 11],
thermodynamic and hydrodynamic conditions (temperature, gas velocity, time of
contact of the granules with hot gas (air) environment) are the main factors which
form the porous structure. In addition, having removed the bulk of the moisture and