3
times during blast operations that involve nitrate- based
explosives.
During the 2000s, significant clouds of red-brown
NOx post blast fume generated by coal mines in Eastern
Australia and the Powder River Basin (Wyoming, USA),
surface metal mines in Canada, and other locations, started
to feature prominently in media headlines. The public
and neighbouring mines became increasingly aware of the
potential hazard of NOx, and in response, mining regu-
latory authorities became increasingly involved in moni-
toring blast generated NOx fume. To address the need
to manage NOx clouds, explosive manufacturers focused
on providing users with oxygen balanced, water resistant
ammonium nitrate-based explosives. Manufacturers also
made concentrated efforts to understand the mechanisms
behind the generation of NOx generation. Explosives com-
panies and government agencies, alone or in corroboration,
developed and published explosives use guidelines aimed at
minimizing NOx generation.
Mines followed by implementing site specific proce-
dures, with wind conditions being a primary control at
many sites to avoid potential NOx clouds drifting over
neighbouring mine sites, public roads, and private/public
lands. Managing blasts to favourable wind conditions often
results in blast delays, with some of these delays amounting
to several days. End users who previously attributed fume
generation to product non-conformances such as off speci-
fication oxygen balance and/or low water resistance have
also come to understand the roles played by factors such
as soft ground, hole depth, and/or collar loading into holes
with minor standing water at the bottom. While these
efforts have realized reductions in NOx fume cloud gen-
eration events, the issue remains present and in need of a
sustainable solution.
NOx blast fumes also cause return to production delays
in underground and surface mines. In underground mines,
blast fumes including NOx should be cleared by ventilation
from working faces and stopes before personnel re-enter the
mine (off-shift blasting) or return to the work area (on-shift
blasting). In surface mines that are working at depth, and
on low wind days, NOx fumes are known to linger in the
bottom of the pit for hours before final clearance can occur.
NOx gases are also known to be trapped in voids in the
muckpile and released during excavation.
AN Cost and Security of Supply
Starting in the mid-2000s, the tightening supply and esca-
lating cost of ammonium nitrate sparked the pursuit of
novel ways to reduce ammonium nitrate content in bulk
explosives. Manufacturers attempted various approaches
including increasing water content to emulsions, variable
density gassing of emulsions, and the addition of bulk-
ing agents such as polystyrene and grain hulls to emulsion
blends. A notable positive outcome observed in some of
these compositions was the reduction and/or near elimi-
nation of NOx fume generation. Concurrently, research-
ers, began exploring for alternatives to ammonium nitrate
based explosive alternatives.
At the time of writing this paper, the ongoing Russia-
Ukraine conflict continues to exert considerable pressure
on global AN sourcing security and increased costs are
reflective of supply. Consequently, end users are striving
to stretch the rock breaking output from every kilo of AN
based explosive used, and actively seeking innovative chem-
ical energy and mechanical rock breaking technologies.
Nitrate and Ammonia in Aqueous Discharge
The chemical composition of mine water discharged to the
environment continues to draw attention and additional
regulation. NH3 0 (un-ionized or free ammonia) is known
to be toxic to marine life. Ammonia and nitrate ions have
been shown to be especially harmful to fish and fish eggs.
Accordingly, mine water discharge can be highly regulated
and monitored by authorities.
Residual bulk ammonia nitrate-based emulsion origi-
nating from product that migrates into cracks/voids in the
blast hole, occurs as spillage at the collar of the hole, and
other causes may end up in blasted rock. In wet-dry- wet
cyclical environments, muck piles and waste rock may be
repeatedly washed by rain and melting snow between dry
periods. This wet-dry-wet cycling environment promotes
decomposition of the emulsion with subsequent leaching
out of ammonia and nitrates into the mine water.
As a license to operate, many mines are required to
capture and/or treat their mine wastewater before discharge
to the outside environment. Scrubbing out ammonia and
nitrate from mine discharge water may be done by chemi-
cal treatment, filtering, and/or bioremediation. Treatments
of large quantities of mine discharge water can be costly.
Inability to manage ammonia discharge into sensitive sur-
rounding watersheds has led to regulatory actions, includ-
ing temporary and permanent mine closures.
Furthermore, to obtain new mining permits or expand
existing ones, it may be required to include plans for water
treatment in the formal application. Capital expenditure
investments for wastewater treatment need to be budgeted
for. In certain regions, these investments can constitute
a significant portion of the mobilization of a new mine,
and in some cases, can undermine the business case for the
development of a new project.
times during blast operations that involve nitrate- based
explosives.
During the 2000s, significant clouds of red-brown
NOx post blast fume generated by coal mines in Eastern
Australia and the Powder River Basin (Wyoming, USA),
surface metal mines in Canada, and other locations, started
to feature prominently in media headlines. The public
and neighbouring mines became increasingly aware of the
potential hazard of NOx, and in response, mining regu-
latory authorities became increasingly involved in moni-
toring blast generated NOx fume. To address the need
to manage NOx clouds, explosive manufacturers focused
on providing users with oxygen balanced, water resistant
ammonium nitrate-based explosives. Manufacturers also
made concentrated efforts to understand the mechanisms
behind the generation of NOx generation. Explosives com-
panies and government agencies, alone or in corroboration,
developed and published explosives use guidelines aimed at
minimizing NOx generation.
Mines followed by implementing site specific proce-
dures, with wind conditions being a primary control at
many sites to avoid potential NOx clouds drifting over
neighbouring mine sites, public roads, and private/public
lands. Managing blasts to favourable wind conditions often
results in blast delays, with some of these delays amounting
to several days. End users who previously attributed fume
generation to product non-conformances such as off speci-
fication oxygen balance and/or low water resistance have
also come to understand the roles played by factors such
as soft ground, hole depth, and/or collar loading into holes
with minor standing water at the bottom. While these
efforts have realized reductions in NOx fume cloud gen-
eration events, the issue remains present and in need of a
sustainable solution.
NOx blast fumes also cause return to production delays
in underground and surface mines. In underground mines,
blast fumes including NOx should be cleared by ventilation
from working faces and stopes before personnel re-enter the
mine (off-shift blasting) or return to the work area (on-shift
blasting). In surface mines that are working at depth, and
on low wind days, NOx fumes are known to linger in the
bottom of the pit for hours before final clearance can occur.
NOx gases are also known to be trapped in voids in the
muckpile and released during excavation.
AN Cost and Security of Supply
Starting in the mid-2000s, the tightening supply and esca-
lating cost of ammonium nitrate sparked the pursuit of
novel ways to reduce ammonium nitrate content in bulk
explosives. Manufacturers attempted various approaches
including increasing water content to emulsions, variable
density gassing of emulsions, and the addition of bulk-
ing agents such as polystyrene and grain hulls to emulsion
blends. A notable positive outcome observed in some of
these compositions was the reduction and/or near elimi-
nation of NOx fume generation. Concurrently, research-
ers, began exploring for alternatives to ammonium nitrate
based explosive alternatives.
At the time of writing this paper, the ongoing Russia-
Ukraine conflict continues to exert considerable pressure
on global AN sourcing security and increased costs are
reflective of supply. Consequently, end users are striving
to stretch the rock breaking output from every kilo of AN
based explosive used, and actively seeking innovative chem-
ical energy and mechanical rock breaking technologies.
Nitrate and Ammonia in Aqueous Discharge
The chemical composition of mine water discharged to the
environment continues to draw attention and additional
regulation. NH3 0 (un-ionized or free ammonia) is known
to be toxic to marine life. Ammonia and nitrate ions have
been shown to be especially harmful to fish and fish eggs.
Accordingly, mine water discharge can be highly regulated
and monitored by authorities.
Residual bulk ammonia nitrate-based emulsion origi-
nating from product that migrates into cracks/voids in the
blast hole, occurs as spillage at the collar of the hole, and
other causes may end up in blasted rock. In wet-dry- wet
cyclical environments, muck piles and waste rock may be
repeatedly washed by rain and melting snow between dry
periods. This wet-dry-wet cycling environment promotes
decomposition of the emulsion with subsequent leaching
out of ammonia and nitrates into the mine water.
As a license to operate, many mines are required to
capture and/or treat their mine wastewater before discharge
to the outside environment. Scrubbing out ammonia and
nitrate from mine discharge water may be done by chemi-
cal treatment, filtering, and/or bioremediation. Treatments
of large quantities of mine discharge water can be costly.
Inability to manage ammonia discharge into sensitive sur-
rounding watersheds has led to regulatory actions, includ-
ing temporary and permanent mine closures.
Furthermore, to obtain new mining permits or expand
existing ones, it may be required to include plans for water
treatment in the formal application. Capital expenditure
investments for wastewater treatment need to be budgeted
for. In certain regions, these investments can constitute
a significant portion of the mobilization of a new mine,
and in some cases, can undermine the business case for the
development of a new project.