101
7.5 Impact Sustainability: Final Remarks
Renewable and nonrenewable resource consumption can be reduced through strategic management of water, energy, and relevant mining materials, which can contribute to the achievement of SDG 6. Evidence shows that 83.98% of water consumption
is reused in open-pit mining, while 24.65% of water used in alluvial mining can be
returned to the same catchment area. It would also be possible to increase the energy
efficiency presented in each stage of the process through improving the adopted
technology, specifically focusing on those stages with both the highest consumptions (“grinding mill” and “extraction” stages in open-pit and the “stripping and
dredging” stage in alluvial mining systems) and the highest losses (“extraction and
services” stage in open-pit mining and the “exploration and services” stage in alluvial mining). Finally, in terms of the excavated inert material in alluvial mining, a
minimum soil tenor equal to 100 mg gold/m
3
must be ensured for the extractive
activity to be technically, economically, energetically, and environmentally viable.
The same is true for open-pit mining with a minimum soil tenor equal to 470 mg
gold/ton. Furthermore, the material from the alluvial process returns to the artificial
pool, while in open-pit it is temporarily stored for beneficiation processes after the
mining system’s end-of-life (EoL) .
Open-pit mining technology presents higher values in relation to each water
resource impact category except water depletion, where it is significantly higher in
alluvial mining technology. This is due to intensive use of water resources with a
value equal to 2.82 × 10
4
m3/year. The total water consumed in open-pit and alluvial
mining technologies is equal to 5.70 × 10
7
ton/year and 9.79 × 10
7
ton/year,
respectively. However, in the alluvial extractive process, the amount of water
returned to the river basin is equal to 2.41 × 10
7
ton/year; and water recirculated into
the process amounts to 4.79 × 10
7
ton/year and 4.42 × 10
5
ton/year in the open and
alluvial systems, respectively, which reduces the water consumption values to
9.83 × 10
6
ton/year and 7.33 × 10
7
ton/year, respectively, as shown in Figs. 7.5
and 7.6.
Improvements in mining projects’ sustainability lie in the efficient use of the
resources coupled with the optimization of process efficiency. This leads to the
reduction of emissions and generated waste, therefore reducing pollution released
in the environment. With these strategies, virgin resources are diminished, which
implies a lower extraction rate. Furthermore, as waste is inherent in the process, it
cannot be avoided. As such, the project must work to improve its material recycling
and reuse strategies.
When designing the waste reuse processes, it is essential to imagine a loop economy, a regenerative system in which resource consumption, waste, emission, and
energy loss are minimized by the slowing, closing, and narrowing of material and
energy loops (Stahel and Reday 1976). This works to encourage reuse, remanufacturing, refurbishing, and recycling when possible. However, primary metals will be
still required throughout the transition toward a more sustainable solution, as it is
7 SDG 6 Clean Water and Sanitation
7.5 Impact Sustainability: Final Remarks
Renewable and nonrenewable resource consumption can be reduced through strategic management of water, energy, and relevant mining materials, which can contribute to the achievement of SDG 6. Evidence shows that 83.98% of water consumption
is reused in open-pit mining, while 24.65% of water used in alluvial mining can be
returned to the same catchment area. It would also be possible to increase the energy
efficiency presented in each stage of the process through improving the adopted
technology, specifically focusing on those stages with both the highest consumptions (“grinding mill” and “extraction” stages in open-pit and the “stripping and
dredging” stage in alluvial mining systems) and the highest losses (“extraction and
services” stage in open-pit mining and the “exploration and services” stage in alluvial mining). Finally, in terms of the excavated inert material in alluvial mining, a
minimum soil tenor equal to 100 mg gold/m
3
must be ensured for the extractive
activity to be technically, economically, energetically, and environmentally viable.
The same is true for open-pit mining with a minimum soil tenor equal to 470 mg
gold/ton. Furthermore, the material from the alluvial process returns to the artificial
pool, while in open-pit it is temporarily stored for beneficiation processes after the
mining system’s end-of-life (EoL) .
Open-pit mining technology presents higher values in relation to each water
resource impact category except water depletion, where it is significantly higher in
alluvial mining technology. This is due to intensive use of water resources with a
value equal to 2.82 × 10
4
m3/year. The total water consumed in open-pit and alluvial
mining technologies is equal to 5.70 × 10
7
ton/year and 9.79 × 10
7
ton/year,
respectively. However, in the alluvial extractive process, the amount of water
returned to the river basin is equal to 2.41 × 10
7
ton/year; and water recirculated into
the process amounts to 4.79 × 10
7
ton/year and 4.42 × 10
5
ton/year in the open and
alluvial systems, respectively, which reduces the water consumption values to
9.83 × 10
6
ton/year and 7.33 × 10
7
ton/year, respectively, as shown in Figs. 7.5
and 7.6.
Improvements in mining projects’ sustainability lie in the efficient use of the
resources coupled with the optimization of process efficiency. This leads to the
reduction of emissions and generated waste, therefore reducing pollution released
in the environment. With these strategies, virgin resources are diminished, which
implies a lower extraction rate. Furthermore, as waste is inherent in the process, it
cannot be avoided. As such, the project must work to improve its material recycling
and reuse strategies.
When designing the waste reuse processes, it is essential to imagine a loop economy, a regenerative system in which resource consumption, waste, emission, and
energy loss are minimized by the slowing, closing, and narrowing of material and
energy loops (Stahel and Reday 1976). This works to encourage reuse, remanufacturing, refurbishing, and recycling when possible. However, primary metals will be
still required throughout the transition toward a more sustainable solution, as it is
7 SDG 6 Clean Water and Sanitation