Content uploaded by René Therrien
Author content
All content in this area was uploaded by René Therrien
Content may be subject to copyright.
Overview of Geothermal Energy Resources in Québec (Canada)
Mining Enviroments
Jasmin Raymond
a)
, René Therrien
a)
, Ferri Hassani
b)
a) Département de géologie et de génie géologique, Faculté des Sciences et de Génie, Université Laval,
Québec (QC), G1K 7P4, Canada, e-mail : jasmin.raymond.1@ulaval.ca
Tel.: +1 418 656 2131; fax: + 1 418 656 7339
b) Department of Mining, Metals and Materials Engineering, Faculty of Engineering, McGill University,
Montréal (QC), H3A 2A7, Canada
Abstract
Rising energy costs, as well as environmental concerns, are driving engineering innovation to reduce energy
consumption while remaining competitive, diversify energy supplies and reduce carbon emissions. In that
context, geothermal energy represents an alternative to common energy sources. Low-temperature geothermal
energy associated with mine sites is gaining acceptance as an economically attractive option for both active
mines and nearby communities. Recent studies assessing the geothermal potential of various mining
environments have shown promising results. These studies assessed closed and active underground mines as
well as flooded open pits and mine waste dumps. Various ground source heat pump designs exist for these
systems to exchange geothermal energy using either ground, surface or close-loop water. Different types of
mining environments therefore host significant geothermal resources that are readily exploitable with today’s
technologies. Research and demonstration projects undertaken in the province of Québec have illustrated the
benefits associated with the exploitation of geothermal energy in mining environments. For example, the
geothermal energy extraction potential of the flooded underground Gaspé Mines, near Murdochville in eastern
Québec, was estimated at 765 kW. This sustainable ground load is calculated for a pumping rate of 0.049 m3/s,
with a production temperature of 6.7 °C and a return temperature of 3 °C. In another project, a surface water heat
pump system using water flooding a quarry was developed at Saint-Bruno-de-Montarville in southern Québec.
The system is used to heat and cool 36 apartments in a condominium complex, having a total surface of
6 039 m2. Research also began at the South dump of the Doyon Mine in the Abitibi region of Québec to evaluate
the technical feasibility of geothermal energy exchange at mine waste dumps. Thermal energy resources
contained in the South Dump and the underlying basement are estimated at 1,678,417 GJ from temperature
profiles measured in 2007. Additional feasibility studies that recently started at flooded underground mines of
British-Colombia, Ontario and the Northwest Territories indicate substantial energy savings. Canada is blessed
with abundant natural resources; it hosts a large number of active and closed mines and it is therefore a prime
target for developing geothermal energy associated with mine sites. Several research initiatives are expected to
further contribute to develop geothermal energy in Canadian mining environments.
Key words: geothermal, energy, low-temperature, mine, water, waste, Québec, Canada.
Nomenclature
C volumetric heat capacity [L
-1
Mt
-2
T
-1
]
H energy resource [L
2
Mt
-2
]
T temperature [T]
where L; length, M; mass, t; time and T; temperature.
Subscripts
a area
b bulk
g ground
r reference
v volume
Introduction
The Springhill, Nova-Scotia, Mine Water Project has been in operation since 1989 and pioneered
geothermal energy exchange using underground mines in Canada. Groundwater flooding Springhill’s
Coal Mine is recovered at 18°C and used to heat and cool buildings with heat pumps. Annual energy
savings are estimated at 600 000 kWh for the operator, Ropak Can Am Ltd.'s, for on site facilities that
cover an area of 7 432 m
2
(CADDET energy efficiency 1992; Jessop et al. 1995). Based on this
success, the Geological Survey of Canada inventoried inactive mines in the province of Québec and
Nova-Scotia (Arkay 1992). Geothermal energy from mines however attracted little interest in the
province of Québec until recently. Current investigation of geothermal energy in a mining
environment began at the Town of Murdochville, which conducted a hydrogeological survey in 2004
to identify the geothermal energy extraction potential of the Copper Gaspé Mines that closed in 1999
(Raymond and Therrien 2008). In another project completed in 2006, real estate developers
constructed a condominium complex that is heated and cooled by heat pumps using the surface water
flooding the Goyer Quarry at St-Bruno-de-Montarville. In the Abitibi region, research is being carried
out at the Doyon Gold Mine to evaluate the technical feasibility of geothermal energy exchange at the
South Dump. Various mining locations of other Canadian provinces are also being studied for their
geothermal potential. Theses include, in British-Columbia, the Britannia Copper Mine (Ghomshei and
Meech 2003), in the Northwest Territories, the Con Gold Mine near Yellowknife (Ghomshei 2007)
and the Diavik Diamond Mine of the Lac de Gras area as weel as, in Ontario, coal mines near
Timmins (Watzlaf and Ackman 2006) and VALE-INCO nickel-copper mines in Sudbury.
Although many studies are being conducted in Canada, the use of ground source heat pump (GSHP)
systems in mining environments remains at the early development stage even though this mature
technology has proven successful (Geothermal Heat Pump Consortium 1997; John Gilbert Architects
2006a,b). GSHPs appear promising for both active and inactive mines. Flooded underground mines as
well as flooded open pits, water retention ponds, mine waste dumps and tailings are considered for
geothermal energy exchange.
This manuscript provides an overview of geothermal resources located in mining environments in the
province of Québec, Canada. Inventories of the province’s closed mines and mine wastes are
reviewed. A summary of current research projects in Québec and other Canadian provinces is
presented and further research needs are identified.
Geological settings and mining history
The province of Québec encloses five main geological provinces (Ministère des Ressources naturelles
1994; Ministère des Ressources naturelles et de la Faune 2007a) and covers a total area of
1,667,926 km
2
(Fig. 10). The Superior Province (4 to 2.5 Ga) contains mostly gneiss and
metasedimentary rocks and it covers a third of the province territory. World class copper, gold, zinc,
nickel and silver deposits are hosted in the Superior Province, mainly in the Abitibi Sub-province, a
volcano-sedimentary Archeen belt. The Churchill Province (2.1 to 1.75 Ga), located in the northern
part of the province and predominantly composed of gneiss and metasidementary rocks, contains iron,
nickel and copper deposits. The Grenville Province (1.2 Ga to 950 Ma) is a metamorphic belt
dominated by gneiss that covers a third of the province territory and hosts major iron and ilmenite
deposits. Grenville host rocks and its sedimentary cover have also been exploited for numerous
industrial minerals and architectural stones. The Saint Lawrence Lowlands (700 to 350 Ma) to the
south are sedimentary platforms with graben structures overlying the Grenville Province. Felsic
intrusions that cross-cut the sedimentary platform are exploited for niobium, industrial minerals and
architectural stones. The Appalachian Orogene (650 to 300 Ma) further south is made of
metamorphosed sedimentary rocks developed at the margin of the Canadian Shield. The orogenic belts
of the Appalachian contain important asbestos and copper deposits, industrial minerals and
architectural stones. The last glaciations during the Quaternary period shaped the topography and left
unconsolidated deposits over parts of the bedrock in almost all regions.
The province’s basement hosts attractive settings for metallic and industrial mineral mines of all sizes
and various operation types. The hydraulic conductivity of host rocks is generally low and dominantly
influenced by fracturation. Crustal heat flow in these old geologic provinces vary from 25 to
65 mW/m
2
with geothermal gradients on the order of 0.01 to 0.02 °C/m (Jessop 1984). Mine
geothermal resources are therefore on the low-enthalpy spectrum of the resource and their sizes are
dominantly influenced by the nature of mining activities that occurred at a site. A mine can in fact host
enhanced resources caused by reworking that occurred during mining. The metallic mines are often
associated with sulfide-bearing environments, which may have a positive influence on geothermal
resources by releasing heat through sulfide oxidation but, on the other hand, be the source of acid mine
drainage that has to be adequately managed. At some minor locality, the calcareous host rock can
buffer acid production. GSHPs used at most sites consequently have to be designed with close loops or
intermediate plate heat exchangers to cope with the basement nature.
An overview of Québec mining history (Ministère des Ressources naturelles et de la Faune 2007b;
Natural Resources Canada 2007; Udd 2000) is given below to outline activities that originally created
mine geothermal resources. Early exploitation of iron and sand quarries that left pits in the landscape
began during the eighteenth century near Trois-Rivières. Metallic and asbestos mines were later
developed in the Southern Appalachian. The first important copper mine, the Eutis Mine, opened near
Sherbrooke in 1865. Asbestos deposits were found near the town of Thetford Mines during the late
1870s and exploitation began in 1881 at the Jeffrey Mine. Exploration in the Abitibi region, near
Chibougamau and Rouyn-Noranda, started in the early 1900s. Several small copper, gold, iron and
asbestos mines opened in the Abitibi, the Appalachian and the Grenville during the 1920-1950 period,
coinciding with the beginning of industrialization in these areas. Mining activities were both
conducted underground and at surface, leaving excavations and wastes on sites which are now
associated with exploitable geothermal resources. Larger exploitations began in the 1950-1970 period.
In 1954, iron delivery from Schefferville’s mine started, the Copper Gaspé Mines near Murdochville
opened, and exploitation of asbestos began at Black Lake near Thetford Mines. With increasing
production, mine sites became more organized and better managed to accommodate larger excavations
and waste piles forming enhanced geothermal resources. Major mines of the Abitibi, such as the
Thompson Bousquet and Doyon mines, opened during the late 1970s. More recently, the LaRonde
Gold mine in Abitibi began exploitation in 1988. The Raglan Copper and Nickel Mine located in
Northern Québec opened in 1997. Today, much of the metallic mining is concentrated in the Abitibi
Sub-province (Fig. 1). Major asbestos deposits of the Appalachian and iron deposits of the Superior
and Grenville provinces are still exploited and numerous smaller quarries are active in the Grenville,
Saint Lawrence Lowlands and the Appalachian (Fig. 1). Several mines have also closed, requiring
major restoration. Both active and restored mines can be targeted for geothermal energy exchange.
Figure 1 The province of Québec major geological provinces, active and closed mines and towns of
interest (modified from Ministère des Ressources naturelles et de la Faune 2007a).
Mining in Québec spurred the development of small communities, traditionally located a few
kilometers away from the mine operations, but generally far from the most populated area of the
province in the corridor between Montréal and Québec City to the South. More than a century of
mining has left a legacy of underground workings, shafts, open pits, water retention ponds and waste
piles that can represent safety and environmental hazards, but also potential low-temperature
geothermal energy reservoirs. These potential reservoirs can be exploited for energy exchange using
GSHPs to generate significant savings for heating and cooling applications. Economic benefits can
help reduce global operation costs of active mines or help to diversify the economy of communities
seeking post-mining activities. Associated reduction of carbon emissions can also help lower
greenhouse gases production.
Low-temperature geothermal energy resources in the mining environment
Geothermal energy reservoirs at metallic and industrial mineral mines commonly found in Québec can
be classified in one of three types according to the GSHP technology that is used: aquifers, surface
water bodies or mine wastes. Groundwater heat pumps (GWHP) can exploit aquifers that are located
in or near underground mines. Surface water heat pumps (SWHP) can use surface water contained in
open pits or water retention ponds. Ground-coupled heat pumps (GCHPs) can be installed in and
below mine waste piles.
Aquifers located in or near underground mines show significant low-temperature geothermal energy
potential (Bazargan Sabet et al. 2008; Ghomshei 2007; Ghomshei and Meech 2003; Jessop et al. 1995;
Malolepszy et al. 2005; Raymond and Therrien 2008; Tóth and Bobok 2007; Watzlaf and Ackman
2006). Enhanced geothermal resources are associated with deep mines, oxidizing host rocks or
increased permeability due to mine workings. This last factor is particularly important in geological
settings of Québec where most host rocks are of low hydraulic conductivity. Dewatered mines where
groundwater is already pumped at active sites and where there is a need to heat and cool
infrastructures such as garages, shops and offices are particularly attractive for geothermal
development. On the other hand, flooded underground closed mines are common and can be exploited
by nearby communities. Arkay (1992) inventoried 165 inactive mines (Fig. 1) and 94 exploration sites
where underground excavations occurred. Most underground mines were exploited for metallic
minerals except at a few locations near Thetford Mines and Gatineau, where they were exploited for
asbestos and industrial minerals, respectively. The inactive underground mines are mostly located in
the Superior Province and in the Appalachian Province near the towns of Rouyn-Noranda, Val d’Or,
Chibougamau, Sherbrooke and Thetford Mines. A few, small inactive underground mines are also
located in the Grenville Province near Gatineau and Québec. Underground mines vary in volume from
10s to more than 100 000 tons of ore removed. An existing geothermal potential was associated with
most underground mines that are located close to a community (Arkay 1992). The flooded Gaspé
Mines near Murdochville has recently been the host of more detailed studies (Raymond and Therrien
2008) that are outlined below.
Although the geothermal potential has been barely explored, flooded open pit mines and retention
ponds used to store runoff water form small to very large surface water bodies suitable for SWHP.
Thermal energy could be exchanged using either close loop systems that circulate water and antifreeze
in a coil installed in surface water, or open systems that directly use the water. Flooded open pits are
commonly found at inactive mines whereas retention ponds are found at both active and inactive
mines, especially those of larger sizes later developed. Arkay (1992) mentions the presence of open
pits at mine sites without, however, giving much details on pit characteristics. Most inactive open pits
are located in the Superior and Appalachian geologic provinces, close to mine communities. The
Ministère des Ressources naturelles et de la Faune (2005) maintains a data base on mine wastes,
including water retention ponds found at active and inactive mines. The 146 ponds inventoried are
mainly located in the Abitibi. Most ponds have neutral pH water but some contain acid water. Each
pond covers an area ranging from 5000 to 1,840,000 m
2
, for a total of 18,470,000 m
2
. Smaller
quarries, that are exploited for industrial minerals and architectural stones below the groundwater
table, can also form reservoirs. Closed quarries are not inventoried but are expected to be found in the
Grenville, Saint Lawrence Lowlands and the Appalachian, with some close to major towns.
Development of SWHP that uses water from a flooded quarry came from real estate developers
themselves. For example, a luxurious condominium complex heated and cooled with open loop SWHP
system using the flooded Goyer Quarry has been constructed in 2006 at Saint-Bruno-De-Montarville
(Leblanc, personal communication, 2007). Heat pump units, with capacity ranging from 3.6 to 5.3 kW,
have been installed in each of the 36 apartments, for a total heated area of 6 039 m
2
. Using
intermediate plate heat exchangers, thermal energy is extracted or returned to the quarry which
contains 8,064,000 m
3
of water. The system is expected to provide users 40 to 50% energy savings.
The developers are currently constructing a second similar condominium and are interested in
developing additional complexes.
Mine waste dumps and tailings are typically abundant at major mines and form large piles of granular
materials where ground heat exchangers could be installed. These are used with GCHP systems to
circulate a mixture of water and antifreeze in close loop piping installed in the ground and exchange
heat with the reservoir by conduction. Easily trenchable tailings and hotter oxidizing waste dumps
may offer settings to install ground heat exchangers at reduced cost. The homogenous and fine grained
nature of tailings allows installation with trenchers that may be cheaper than with conventional
backhoe loader. The ground temperature has a strong influence on the required ground heat exchanger
length, as can be seen using the standard sizing equation (ASHRAE 2007; Bernier 2000; Kavanaugh
and Rafferty 1997). An increase in ground temperature of only 2 °C permits significantly shorter
exchanger length for heating mode designs. Waste dumps and underlying host rocks having a warmer
temperature due to sulfide oxidation consequently appear to be attractive reservoirs, where cheaper
installation costs may be possible. Oxidizing waste dumps are expected at metallic mines of the
Abitibi and some localities of the Appalachian. Both waste dumps and tailings typically cover large
areas sufficiently to install multiple boreholes or trenches for heat pump systems of high capacity in
large buildings. The Ministère des Ressources naturelles et de la Faune (2005) inventoried 555 waste
piles in the province Québec. Most of them are located in the Abitibi near Rouyn-Noranda, Val d’Or
and Chibougamau, in the Appalachian near Sherbrooke and Thetford Mines and in the Greenville near
Scherfferville and Fermont. Each pile covers an area ranging from 1000 to 2,800,000 m
2
, for a total
waste dump area of 39,760,000 m
2
and a total tailing area of 93,420 000 m
2
. About 55 waste dumps
are categorized as acidic and are undergoing mineral oxidation, which may raises their temperature
compare to surrounding geological formations. A research project that aims to evaluate the technical
feasibility of geothermal energy extraction from mine waste dumps has started at the Doyon Mine and
is outlined below.
Gaspé Mines project
Closure of the Gaspé Mines in 1999 and associated smelter in 2002 has provided an opportunity for
the Town of Murdochville (Fig. 1) to explore its geothermal resources. Technical and economic
feasibility studies were conducted from 2004 to 2006 to evaluate the mines geothermal potential. The
work consisted in site characterization, pumping test, groundwater flow modelling and economic
assessment. A complete description of the technical study can be found in Raymond and Therrien
(2008) and economical considerations are detailed in the report of Cavanaugh-Morin (2006).
The Gaspé Mines (Fig. 2) are excavated in the Early Devonian Gaspé Superior Limestone Group. Two
open pits and three main underground zones were mined. Groundwater flows toward the Copper
Mountain Pit where water level has been rising since mine closure. Thermal energy resources
contained in the mine was estimated to 61,000 GJ using the local geothermal gradient (0.011 °C/m)
and the estimated water volume contained in underground workings (3,732,300 m
2
). This energy is the
equivalent of that contained in 10,914 oil barrels (US) assuming that burning one crude oil (kerosene)
barrel releases 5589 MJ. Mine water energy is being renewed by the earth heat flux locally evaluated
to 51 mW/m
2
.
A pumping test was performed in the former mining shaft P1100 (Fig. 2) to determine underground
workings and host rock hydraulic properties. Pumping was conducted for 3 weeks at a rate averaging
0.062 m
3
/s (3720 l/m) and a maximum drawdown of 3.63 m was observed. The hydraulic conductivity
of the workings and host rock was estimated equal to 2.3 X 10
-2
m/s and 4.5 X 10
-5
m/s, respectively,
using groundwater flow modelling. Pumped water temperature measured during the test averaged
6.7 °C. Groundwater flow modelling was subsequently performed to simulate pumping for geothermal
heating at the town industrial park. To estimate the site geothermal potential, the modelled drawdown
surface was calculated to evaluate the captured energy, which was compared to the energy that can be
extracted using heat pumps. The sustainable energy extraction rate was estimated to 765 kW for a
pumping rate of 0.049 m
3
/s (2940 l/m), assuming that the 6.7 °C pumped water temperature can be
lower to 3 °C using a GWHP system.
The Town of Murdochville is interested in developing a geothermal energy distribution network at its
industrial park, which is located over the mine workings. Groundwater could be pumped from a
former mining shaft and delivered to buildings equipped with their own heat pump systems having a
total capacity of 822 kW. The coefficient of performance at heat pump units assumed for the economic
assessment varied with water temperature from 4.4 to 3.4 such that the ground load remains below the
site geothermal potential. Investment costs associated to the construction of such a network are
evaluated at 523,124 $CAN. Annual energy savings provided with GWHPs, using the network at its
full capacity, is on the order of 2,494,500 kWh, offering net energy savings of 143,600 $CAN
annually and a pay back period of 3.6 years. The town is currently looking for partnership to develop
their geothermal resources.
Figure 2 Gaspé Mines schematic cross-section showing hydrostratigraphic details of units (Raymond
and Therrien 2008). Section redrawn after Bernard and Procyshyn (1992). ICove: Indian Cove
Formation; SHeap: Ship Head Formation; A-limestone: argillaceous limestone; C-mudstone:
calcareous mudstone; Qz: quartz; Ca: calcite; Ab-Mi: albite-microcline. * Average mineralogy
inferred from geochemical data (Wares and Berger 1993). ** Porosity estimated on the basis of the
rock type classification proposed by Freeze and Cherry (1979). Bulk thermal conductivity
b
and heat
capacity Cp
b
calculated from mineralogy with (Brailsford and Major 1964) and (Waples and Waples
2004a,b).
Doyon Mine project
The Doyon Gold Mine (Fig. 1) has been operating since 1978. The exploitation started in two open
pits but mining has been conducted underground since 1989. The South Dump (Fig. 3) was
constructed from 1983 to 1987, without significant modifications since. Today, the temperature of this
pile of waste rocks is significantly higher than the surrounding host rock temperature, which makes it
attractive for geothermal energy exchange. At the site, waste rocks cover an area of 549,400 m
2
and
has a maximum thickness of about 35 m. The dump is dominantly constituted of sericite schist
fragments deposited on a silty overburden. The underlying host rocks are mostly metavolcanics. Acid
mine drainage was first observed in 1985 with peak production near 1988. Effluents were
characterized at that time by a pH near 2 and total dissolved solids of about 200,000 mg/l (Lefebvre et
al. 2001a). Extensive environmental characterization and numerical modelling that aimed to better
understand the production of acid mine drainage was conducted during the 1900’s (Gélinas et al. 1994;
Lefebvre 1994; Lefebvre et al. 2001a; Lefebvre et al. 2001b). Recent numerical modelling of sulfide
oxidation and groundwater flow using data from the South Dump brought a better understanding of
the physicochemical processes responsible for acid mine drainage (Molson 2005). Research is
currently conducted by Université Laval to evaluate the technical feasibility of geothermal energy
exchange at the South Dump.
Figure 3 Topographical map of the South Dump at the Doyon Mine showing the location of
observation wells.
Figure 4 Temperature profiles measured in an exploration hole (ML-143) more than 1 km away from
the dump and in monitoring wells (BH-1, BH-4, BH-5, BH-6) installed at the South Dump of the
Doyon Mine.
Temperature measurements made during the 1900’s indicated that the dump internal temperature
ranged from 20 to 65 °C (Choquette and Gélinas 1996; Lefebvre et al. 2001a). The temperature has
since been slowly decreasing. Additional temperature measurements were performed in 2007 at the
existing boreholes located in Fig. 3. Only four of the seven boreholes that were drilled during the
1990’s remained on site. These boreholes are observation wells drilled through the waste pile and
about 6 to 13 m of the underlying overburden and host rock. BH-5 is however drilled in the waste rock
only and does not cross cut all the pile thickness. A flexible liner was installed in the boreholes that
were filled with water. Temperature was measured in the water with a thermistor having a resolution
of 0.05 °C and an accuracy of 0.1 °C. An additional temperature profile was measured in an
exploration diamond drilled hole (ML-143) located more than 1 km away from the waste dump, to
evaluate the undisturbed ground temperature. All measurements are shown in Fig. 4. The waste dump
has a temperature ranging from 13 to 44 °C at depths below 5 m, which is significantly above the
mean undisturbed ground temperature of 5.1 °C. Temperature of the overburden and host rock below
the waste pile is also warmer, with temperature ranging from 36 to 18 °C in the first 6 to 13 m below
the waste pile. The temperature gradient is estimated below the drilled depth using the slope of the
gradient measured in the host rock. Using this estimated gradient, the undisturbed ground temperature
is reached at depth of 81 to 116 m.
The thermal energy resources stored in the South Dump are calculated below. The energy resource
contained per unit volume H
v
at wells BH-1, BH-4 and BH-6 is initially calculated for each
temperature measurement below 5 meters with:
gb,rgv
)( CTTH
eq. 1
where T
g
is the ground temperature, T
r
is the reference temperature and C
b,g
is the bulk volumetric heat
capacity of the ground. The upper 5 meters of waste dump is not considered because its temperature
significantly fluctuates with daily and monthly atmospheric temperature variations. The undisturbed
ground temperature is used for T
r
, which assumes that thermal energy resources are available until the
waste dump and underlying material is cooled to 5.1 °C. Temperatures measured in the waste pile, the
overburden and host rock and temperatures extrapolated in the host rock are used for T
g
. Volumetric
heat capacities of 1.98 MJK
-1
m
-3
, 3.02 MJK
-1
m
-3
and 2.34 MJK
-1
m
-3
for the waste dump, overburden
and host rock, respectively, are reported by Lefebvre (1994) and used here. The energy resource
contained per unit area H
a
is then calculated using:
z
HH
H
2
)( iv,1iv,
a
eq. 2
where z is the interval between two temperature measurements (i+1 and i). The H
a
values are
summed over the well and extrapolated depths to determine the energy contained per unit surface at
each well. Energy at each well is averaged and then multiplied by the waste dump surface
(549,400 m
2
) to estimate the total energy contained in the South Dump and underlying materials.
Calculation details are outlined in Table 1.
Table 1 Doyon Mine South Dump energy resources
Cb waste dump1 (MJK-1m-3) 1.98
Cb overburden1 (MJK-1m-3) 3.02
Cb host rock1 (MJK-1m-3) 2.34
Ha BH-1 (MJm-2) 2003
Ha BH-4 (MJm-2) 2647
Ha BH-6 (MJm-2) 4514
Ha average (MJm-2) 3055
Waste dump area (m2) 549,400
Total energy resources (GJ) 1,678,417
Equivalent oil barrels (US)
5589 MJ/barrels 300,307
1- (Lefebvre 1994)
This resource base calculation indicates that total energy host in the South Dump and underlying
materials (i.e. accessible and inaccessible heat) is equal to 1,678,417 GJ, which represents the amount
of energy that is released by burning 300,307 oil (kerosene) barrels (US). The waste dump energy is
slowly dissipated by heat conduction. The evolution of the energy resources in the dump can be
evaluated with temperature measurements collected site from 1991 to 1996 (Choquette and Gélinas
1996). The relative energy decrease (Fig. 5) is calculated in the waste dump only because of limited
former data assuming that the 1991 temperature represented near peak values (i.e. 100%). The
decrease of energy resources was rapid during the first five years and has slowed down during the last
ten years, suggesting that significant resources are still available for the next decades.
Figure 5 Relative energy decrease at the South Dump of the Doyon Mine.
Part of the South Dump thermal energy resources could be exploited with a GCHP system using
ground heat exchangers. The energy extracted could be used for space heating. The GCHP system
could also be used for cooling, and the heat released at the dump site could contribute to preserve
energy resources for a longer period. Numerical modelling of heat exchange at the South Dump is
planned to evaluate the technical feasibility of such exploitation.
Other Canadian projects
Geothermal projects in mining environments have been undertaken in other Canadian provinces.
Studies focused on the potential and feasibility of geothermal energy exchange at underground flooded
mines of various natures. The Copper Britannia Mine in British-Colombia was investigated by
Ghomshei and Meech (2003). It was proposed to use the mine water that is resurging at 15 °C and at a
pH of 4 to 4,5 to heat homes of the nearby community. A district heating system having a capacity of
1.2 to 5 MW could be operated with a power supply of 0.24 to 1 MW only. Acid resistant plate heat
exchangers would be necessary to cope with the water acidity. Investment costs of a district heating
system at Britannia were evaluated at 2 to 2.5 M$CAN with annual net energy savings of 25 to
35 k$CAN giving a payback of about 5 to 8 years.
The Gold Con Mine of the Northwest Territories that closed in 2003 can potentially be used for heat
exchange with a system supplying buildings at the city of Yellowknife (Ghomshei 2007). A
demonstration project having a 300 kW heating capacity and a total power supply of 90 kW could be
developed using water from a single mining shaft. Capital costs of such a demonstration project are
estimated to 768 k$CAN with annual net energy savings of 95 k$CAN giving a pay back period of
about 8.1 years. Heating capacity may be expanded to 2 MW (0.4 MW power supply) using water that
can be above 40 °C in deeper mine levels.
Diamond mines near the Lac de Gras area of the Northwest Territories are being studied by The Earth
Mine Energy Research Group (EMERG) of McGill University. This area, known as the third biggest
diamond producer of the world, is the host of three actives mines (Jericho, Ekati and Diavik) and two
mine projects planned to be developed (Gahcho Kue and Snap Lake). Mining operations in kimberlite
pipes are both conducted at surface and underground. High water inflow in these fractured igneous
rocks has to be adequately managed in excavations. At the underground Diavik Mine, water is pumped
at an average rate equals to 0.423 m
3
/s (27,778 l/m) and a temperature around 6 °C. Pumped water
could be adequately managed to provide geothermal heating for operational mine infrastructures.
Ontario’s coal mines near Timmins were identified potential geothermal resources. A study briefly
reported by Watzlaf and Ackman (2006) indicates that 12 to 13 °C water at depth of 200 to 250 m
could be used to heat an exposition/convention center.
Nickel and copper mines of Sudbury in Ontario has also been targeted by EMERG for further
geothermal studies. One of the six VALE-INCO mines in this region has a depth of more than 1200 m
and is a potential location for geothermal development. Temperature in the deepest part of the mine is
assumed equal to 25 °C. Groundwater infiltrates the underground mine at high rates through the
brecciated Archean basement. Mining operations are expected to proceed to deeper levels. Dewatering
mine water could be used with GWHP to heat mine infrastructures and homes of Sudbury’s
communities having a total population of 160,000 residents.
Conclusions
The mining sector has an opportunity to make an additional step toward sustainability using the
abundant geothermal resources of mine sites. 165 closed mines, 146 retention ponds and 555 mine
waste piles have been inventoried throughout the province of Québec. All these represent settings with
potential geothermal resources that can be exploited with GSHPs to provide energy savings and reduce
green house gases emissions. Such major resources are typically far from populated areas but can be
developed locally to diversify energy supplies. Active mines are targeted potential users because of
their energy needs and close proximity. Mining communities facing site closure have so far shown the
most interest to develop this resource.
Original researches have been initiated to evaluate the geothermal potential of mining environments.
Work carried at the Gaspé Mines near Murdochville during a feasibility study helped to define the
hydraulic conductivity of underground workings and the site potential. The project reported at the
South Dump of the Doyon Mine first evidenced the large geothermal resources associated with an
oxidizing waste dump. Various initiatives undertaken in Canada have also contributed to resource
characterization and feasibility assessment.
The capital cost associated with GSHP installation is greater than that of conventional systems
resulting in longer pay back period. Additional research efforts can be conducted to minimize GSHP
installation costs and promote the use of this technology. Abundant resources of the mining
environment, being easily accessible and/or having enhanced characteristics such as host rock
permeability or temperature, offer possibilities to install GSHP at lower cost. Pay back of projects
reported in this manuscript was down to 3.6 to 8.1 years. Other mines can allow reduced installation
costs. Inventories of geothermal resources in mining environments could therefore be improved and
updated to target the most attractive sites. Although some mines have been extensively characterized
from an environmental perspective, there is a lack of data on temperature and thermal properties at
most sites. Additional field characterization at some promising locations will provide data to design
economical GSHP systems. Field testing methods of thermal properties could be improved to obtain
better data in diversified environments allowing more precise designs. Heat exchange modelling
remains useful to evaluate feasibility and optimize designs. Analytical and numerical modelling tools
could be improved to simulate heat exchanges in complex environments such as mine sites. Research
collaborations with the mining sector and affected communities represent the first step toward
demonstration projects to promote the use of GSHP in mining environments.
Acknowledgement
M. Louis Bienvenu and the Ministère des Ressources naturelles et de la Faune are acknowledge for
sharing their data base on mine wastes. Mr. Annie Blier and IAMGOLD Corporation are
acknowledged for giving access to the Doyon Mine site and data. We also wish to gratified work
collaboration with the town of Murdochville and Xstrata at the Gaspé Mines. Funding for this research
was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the
Fonds québecois de la recherche sur la nature et les technologies (FQRNT).
References
Arkay K (1992) Geothermal energy from abandoned mines: A methodology for an inventory, and inventory data
for abandoned mines in Québec and Nova Scotia. Open file report 3825. Geological Survey of Canada, Alberta,
45 pp.
ASHRAE (2007) Geothermal Energy. In: ASHRAE (Ed), ASHRAE handbook. Heating, ventilating, and air-
conditioning applications. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta,
p 32.1-32.30.
Bazargan Sabet D, Demollin E and Van Bergermeer J-J (2008) Geothermal use of deep flooded mines, Post-
Mining 2008 symposium Proceedings, Nancy, p 1-11.
Bernard P and Procyshyn EL (1992) Geology and Mineral Exploration at Mines Gaspé., 94th CIM Annual
Meeting, Montréal, Canada, p 1-15.
Bernier M (2000) A Review of the Cylindrical Heat Source Method for the Design and Analysis of Vertical
Ground-Coupled Heat Pump Systems. Proceedings of the Fourth International Conference on Heat Pumps in
Cold Climates Conference, Caneta Research Inc., Aylmer, p 1-14.
Brailsford AD and Major KC (1964) The thermal conductivity of aggregates of sevral phases, including poreous
materials. Journal of Applied Physics 15(3): 313-319.
CADDET energy efficiency (1992) Geothermal mine water as energy source for heat pump. Available on the
Internet: http://oee.nrcan.gc.ca/publications/infosource/pub/ici/caddet/english/pdf/R122.pdf.
Cavanagh-Morin G (2006) Évaluation économique du projet géothermie Mines Gaspé. Unpubl. Report, Les
Services Technologiques Duo.
Choquette M and Gélinas PJ (1996) Base de données de monitoring - Halde Sud, la Mine Doyon, Québec.
Unpubl. Report, Université Laval, Québec.
Freeze RA and Cherry JA (1979) Groundwater. Prentice-Hall, Englewood Cliffs, 604 pp.
Gélinas PJ, Lefebvre R, Choquette M, Isabel D, Locat J and Guay R (1994) Monitoring and modeling of acid
mine drainage from waste rocks dumps, la Mine Doyon case study. Unpubl. Report, Université Laval, Québec.
Geothermal Heat Pump Consortium (1997) Municipal Building, Park Hills, Missouri. Available on the Internet:
http://www.geoexchange.org/pdf/cs-064.pdf.
Ghomshei MM (2007) Geothermal energy from Con Mine for Heating the City of Yellowknife, NWT: A
concept study. Available on the Internet:
http://www.yellowknife.ca/__shared/assets/Geothermal_Study_Final_Report6259.pdf.
Ghomshei MM and Meech JA (2003) Usable Heat from Mine Waters : Coproduction of Energy and Minerals
from "Mother Earth". Proceedings of the 4th IPMM Conference, Sendai, p 1-8.
Jessop AM, Lewis TJ, Judge AS, Taylor AE and Drury MJ (1984) Terrestrial heat flow in Canada.
Tectonophysics 103(1-4): 239-261.
Jessop AM, MacDonald JK and Spence H. (1995) Clean Energy from abandoned mines at Springhill, Nova-
Scotia. Energy Sources 17(1): 93-106.
John Gilbert Architects (2006a) Sustainable housing, Glenalmond Str. Available on the Internet:
http://www.johngilbert.co.uk/pdf_files/innovation/9_Shettleston.pdf.
John Gilbert Architects (2006b). A technical report on Ochil View, Lumphinnans. Available on the Internet:
http://www.johngilbert.co.uk/pdf_files/JGA_Lumphinnans_tech.pdf.
Kavanaugh SP and Rafferty K (1997) Ground-source heat pumps: design of geothermal systems for commercial
and institutional buildings. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta,
167 pp.
Lefebvre R. (1994) Caractérisation et modélisation numérique du drainage minier acide dans les haldes de
stériles. Ph.D. Thesis, Université Laval, Québec, 375 pp.
Lefebvre R, Hockley D, Smolensky J and Gélinas PJ (2001a) Multiphase transfer processes in waste rock piles
producing acid mine drainage. 1: Conceptual model and system characterization. Journal of Contaminant
Hydrology 52(1-4): 137-164.
Lefebvre R, Hockley D, Smolensky J and Lamontagne A (2001b) Multiphase transfer processes in waste rock
piles producing acid mine drainage. 2: Applications of numerical simulation. Journal of Contaminant Hydrology
52(1-4): 165-186.
Malolepszy Z, Demollin-Schneiders E and Bowers D (2005) Potential use of geothermal mine water in Europe.
Proceedings of the World Geothermal Energy Congress, Antalya, p 1-3.
Ministère des Ressources naturelles (1994) Géologie du Québec. Service de la géoinformation, Québec, 154 pp.
Ministère des Ressources naturelles et de la Faune (2005) Inventaire des aires d’accumulation de résidus miniers
présentes au Québec. Computerized data base, internal documentation. MRNF Division des Mines, Québec.
Ministère des Ressources naturelles et de la Faune (2007a) Aperçu géologique. Avialable on the Internet at:
http://www.mrnf.gouv.qc.ca/mines/geologie/geologie-apercu.jsp.
Ministère des Ressources naturelles et de la Faune (2007b) Histoire de l'industrie minière. Available on the
Internet: http://www.mrn.gouv.qc.ca/mines/industrie/industrie-histoire.jsp.
Molson JW, Fala O, Aubertin M, and Bussière B (2005) Numerical simulation of pyrite oxidation and acid mine
drainage in unsaturated waste rock piles. Contaminant Hydrogeology 78: 343-371.
Natural Resources Canada (2007) A Chronology of Minerals Development in Canada. Available on the Intenet:
http://www.nrcan.gc.ca/ms/stude-etudi/chro_e.htm.
Raymond J and Therrien R (2008) Low-temperature geothermal potential of the flooded Gaspé Mines, Québec,
Canada. Geothermics, 37(2): 189-210.
Tóth A and Bobok E (2007) A prospect geothermal potential of an abandoned copper mine. Proceedings of the
Thirty-Second Workshop on Geothermal Reservoir Engineering, Stanford University, p 1-3.
Udd JE (2000) A Century of Achievement - The Development of Canada’s Minerals Industries. CIM Special
Volume, 52. Canadien Institute of Mining, Montréal, 206 pp.
Waples DW and Waples JS (2004a) A review and evaluation of specific heat capacities of rocks, minerals, and
subsurface fluids. Part 1: minerals and nonporous rocks. Natural Resources Research 13(2): 97-122.
Waples DW and Waples JS (2004b) A review and evaluation of specific heat capacities of rocks, minerals, and
subsurface fluids. Part 2: fluids and porous rocks. Natural Resources Research 13(2): 123-130.
Wares R and Berger J (1993) Stratigraphie, structure et lithogéochimie de la région de Mines Gaspé. Unpubl.
Report. IXION Research Group, Montréal, Canada, 34 pp.
Watzlaf GR and Ackman TE (2006) Underground mine water for heating and cooling using geothermal heat
pump systems. Mine Water and the Environment 25(1): 1-14.
