XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 775
to be determined through the testwork performed to
date.
• Charge Density, Current Efficiency
A higher CE requires a lower CD, which results
in increased electrode surface area and footprint
required to achieve the same NaCN recovery capac-
ity. With only two CE/CD studied, additional test-
work to find the optimal charge density for each pro-
cess solution could lower the capital and operating
costs substantially.
• Cost of electricity
High conductivity allows for an efficient process, as
shown for Mexican case study returning a positive
net return. However, if the cost of electricity was
to increase to $0.16 USD/kWh, the project would
lose this economic driver, and would have to rely on
other factors to drive its implementation.
• Integration into the existing metallurgical facility
The Mexican CS was an optimal condition for the
EO (low pH, high TDS solution, removing need for
IX concentration), and no need for large removal,
allowing for efficient SCN oxidation. The Abitibi
mine was the opposite, with incorporation into a
low TDS tailings facility. For these situations, where
the economics are not sufficiently strong to drive the
project forward, other factors and benefits of the EO
process need to be considered.
• Lifecycle cost of cyanide (purchase, delivery,
destruction, potential liability and risks)
There are additional costs associated with cyanide
aside from the pure purchase costs. For every addi-
tional kilogram of new cyanide brought onto a site,
the current risk as well as future liability increases.
Some of the risks and liabilities of cyanide include:
– Transportation risks
– Storage risks
– Cyanide Destruction costs
– Residual cyanide toxicity risks and liability
– Social license risk
– Future environmental liability through cyanide
oxidation by-products and TDS increases in the
receiving environment
• Extent of SCN removal required
For sites where there is an environmental require-
ment for SCN removal, placing an EO circuit would
be prohibitive, as the electricity costs increase sub-
stantially with %removal. This is why the IX cir-
cuit was required for the Abitibi project. However,
when an EO circuit can be applied as a ‘kidney’ and
designed for mass removal rather than discharge
quality, using a low %SCN removal across the EO
provides an additional level of protection against the
negative influence of TDS, and chloride on cyanide
recovery.
• Buildup of solution TDS, and availability of fresh
water
The Mexican project has a closed water balance with
little to no availability of fresh water. For this situa-
tion, reduction in process solution TDS is a major
design parameter, with other methods of SCN
removal could not attain.
REFERENCES
Ding, L., Liang, H.C., Kratochvil, D. 2022. Preliminary
Engineering Design and Assessment of Cyanide
Recovery from Thiocyanate at Mexican Mine.
Vancouver, BC: BQE Water.
Douglas Gould, W., King M., Mohapatra B., et al., 2012. A
critical review on destruction of thiocyanate in mining
effluents. Minerals Engineering, 2012. 34: p. 38–47.
Ljubetic, K., Ding, L., Baker, B., and Kratochvil, D. 2021.
Cyanide Recovery from Thiocyanate using Electro-
oxidation at Mexican Mine. Vancouver, BC: BQE
Water.
Zolfaghari, M., and Magdouli, S. 2020. Study of
Thiocyanate Removal from Mine Water Using Ion
Exchange Combined with Electro-Chemical Oxidation
Processes. Rouyn-Noranda, Quebec: CTRi.
to be determined through the testwork performed to
date.
• Charge Density, Current Efficiency
A higher CE requires a lower CD, which results
in increased electrode surface area and footprint
required to achieve the same NaCN recovery capac-
ity. With only two CE/CD studied, additional test-
work to find the optimal charge density for each pro-
cess solution could lower the capital and operating
costs substantially.
• Cost of electricity
High conductivity allows for an efficient process, as
shown for Mexican case study returning a positive
net return. However, if the cost of electricity was
to increase to $0.16 USD/kWh, the project would
lose this economic driver, and would have to rely on
other factors to drive its implementation.
• Integration into the existing metallurgical facility
The Mexican CS was an optimal condition for the
EO (low pH, high TDS solution, removing need for
IX concentration), and no need for large removal,
allowing for efficient SCN oxidation. The Abitibi
mine was the opposite, with incorporation into a
low TDS tailings facility. For these situations, where
the economics are not sufficiently strong to drive the
project forward, other factors and benefits of the EO
process need to be considered.
• Lifecycle cost of cyanide (purchase, delivery,
destruction, potential liability and risks)
There are additional costs associated with cyanide
aside from the pure purchase costs. For every addi-
tional kilogram of new cyanide brought onto a site,
the current risk as well as future liability increases.
Some of the risks and liabilities of cyanide include:
– Transportation risks
– Storage risks
– Cyanide Destruction costs
– Residual cyanide toxicity risks and liability
– Social license risk
– Future environmental liability through cyanide
oxidation by-products and TDS increases in the
receiving environment
• Extent of SCN removal required
For sites where there is an environmental require-
ment for SCN removal, placing an EO circuit would
be prohibitive, as the electricity costs increase sub-
stantially with %removal. This is why the IX cir-
cuit was required for the Abitibi project. However,
when an EO circuit can be applied as a ‘kidney’ and
designed for mass removal rather than discharge
quality, using a low %SCN removal across the EO
provides an additional level of protection against the
negative influence of TDS, and chloride on cyanide
recovery.
• Buildup of solution TDS, and availability of fresh
water
The Mexican project has a closed water balance with
little to no availability of fresh water. For this situa-
tion, reduction in process solution TDS is a major
design parameter, with other methods of SCN
removal could not attain.
REFERENCES
Ding, L., Liang, H.C., Kratochvil, D. 2022. Preliminary
Engineering Design and Assessment of Cyanide
Recovery from Thiocyanate at Mexican Mine.
Vancouver, BC: BQE Water.
Douglas Gould, W., King M., Mohapatra B., et al., 2012. A
critical review on destruction of thiocyanate in mining
effluents. Minerals Engineering, 2012. 34: p. 38–47.
Ljubetic, K., Ding, L., Baker, B., and Kratochvil, D. 2021.
Cyanide Recovery from Thiocyanate using Electro-
oxidation at Mexican Mine. Vancouver, BC: BQE
Water.
Zolfaghari, M., and Magdouli, S. 2020. Study of
Thiocyanate Removal from Mine Water Using Ion
Exchange Combined with Electro-Chemical Oxidation
Processes. Rouyn-Noranda, Quebec: CTRi.