XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3915
by the ratio of hard, medium and soft components in the
feed where higher ratios of more competent components
negatively impact the throughput. Preferential accumu-
lation of most competent components can limit milling
capacity especially when SAG feed is comprised of high
proportion of hard components. The extreme case is simu-
lated by the single component scenario of 100:0:0. On the
other side, slurry pooling occurs specially when processing
softer components at high ratios, i.e., the single component
estimates the extreme condition by 0:0:100. A possible
advantage of multi-component modelling as proposed in
this paper would be the ability to predict chance of material
build-up or slurry pooling based on a quantified knowledge
of ore competence variability.
CONCLUSIONS AND
RECOMMENDATIONS
A methodology, based on the Extended Drop Weight
Testing approach known as ExDWT, is proposed to quan-
tify proportions/percentages of different competence com-
ponents within an ore sample by relying on direct breakage
measurements. The methodology presented in this paper,
allows for multi-component breakage modelling and
description based on the ExDWT ore characterisation
approach. It relies on the measurement of ‘tn-family’ per set
of particles that is generated by ExDWT. The data used to
describe not only the extent of ore competence variability
but also to estimate the proportion of different components
of competence within a representative sample. A comparison
of competence components of Sample C and its pebbles
(Sample D) from Barrick Cortez gold mine is insightful as
24% increase in pebbles shows how the ExDWT data sheds
light on why variable ore types are exposed to characteristic
changes as processed through the circuit. This information
which could be used to customize circuit designs best to
the ore comminution characteristics for improved energy
efficiency.
It is acknowledged that the proportion of key compo-
nents within the fresh feed can vary—nonetheless simulat-
ing a range of scenarios including different proportions of
key competences should provide a basic, but helpful knowl-
edge of such a variation. The simulated scenarios imply that
the SAG mill performance is likely to be highly influenced
by the ore nature and the extent of ore-induced operational
variability. For this purpose, 13 scenarios were simulated to
explore the performance of SAG milling when introduced
to ore feeds with a range of competence components. The
simulation results at Jb=12.1% shows a throughput of
550 t/h for the actual ore composed of 24% hard, 43%
medium and 33% soft components while the at extreme
scenarios (100% hard and 100% soft) the throughput 452
t/h (–18%) and 792 t/h (+44%), indicating possible range
of changes induced by a multi-component ore and/or dif-
ferent ore blends. That is, the proposed breakage charac-
terisation, modeling and description approach could assist
in quantifying components of competence within sampled
ore feeds, and then exploring likely impact of the grind-
ing. Therefore a more effective integration of orebody
knowledge into evaluations should allow for quantifying a
more representative risk profile, particularly beneficial for
design and optimisation as well as addressing operational
bottlenecks during specific periods over the life-of-mine.
However, such an analysis will also require development
of sampling strategies which preserve the intrinsic degree
of variation within an ore type instead of reducing it by
blending. In addition to competence variability, particle
size distribution (PSD) variability can also have a signifi-
cant impact on mill performance (which is not with the
scope of this paper), especially the power balance between
SAG and ball mill—which is comprehensively explored
and documented in several mine-to-mill projects.
Ore feed variability presents simultaneous challenges
and opportunities. The degree to which its associated risks
can be unveiled before transforming into significant eco-
nomic losses over the life-of-mine (LOM) depends on how
detailed key sources of uncertainty are captured, described
and accounted in decision-making. In this regard, Smith et
al. (2022) explored the likely impact of applying a Mine-
to-Mill strategy on the asset value through Strategic Mine
Planning (SMP), which offers the assessment and ranking
of improvement strategies over the life of the mine (namely,
Strategic Mine-to-Mill). Their results for a copper deposit
indicated a potential improvement of 7.9% in Net Present
Value (NPV) would be achievable over the LOM through
value-driven drill-and-blast practices. Faramarzi and Smith
(2023) later established Integrated Strategic Mine Planning
(I-SMP) which allowed for simulating the strategic impact
of blast fragmentation and ore competence variability on
NPV over the LOM. As a future work, the I-SMP com-
bined with proposed multi-component breakage modelling
and description approach in this paper aids in quantifying
how different components of competence within a deposit
may influence the asset value—therefore mining schedules
could be tuned to smooth out risks in certain periods—
which should establish a meaningful link between the min-
ing and milling plans and practices. Additionally, one of the
main risks of feed competence variation is the ability of SAG
mill to maintain the load. A survey is required for mapping
the results of the proposed multi-component modelling
and description approach into an integrated value-chain
by the ratio of hard, medium and soft components in the
feed where higher ratios of more competent components
negatively impact the throughput. Preferential accumu-
lation of most competent components can limit milling
capacity especially when SAG feed is comprised of high
proportion of hard components. The extreme case is simu-
lated by the single component scenario of 100:0:0. On the
other side, slurry pooling occurs specially when processing
softer components at high ratios, i.e., the single component
estimates the extreme condition by 0:0:100. A possible
advantage of multi-component modelling as proposed in
this paper would be the ability to predict chance of material
build-up or slurry pooling based on a quantified knowledge
of ore competence variability.
CONCLUSIONS AND
RECOMMENDATIONS
A methodology, based on the Extended Drop Weight
Testing approach known as ExDWT, is proposed to quan-
tify proportions/percentages of different competence com-
ponents within an ore sample by relying on direct breakage
measurements. The methodology presented in this paper,
allows for multi-component breakage modelling and
description based on the ExDWT ore characterisation
approach. It relies on the measurement of ‘tn-family’ per set
of particles that is generated by ExDWT. The data used to
describe not only the extent of ore competence variability
but also to estimate the proportion of different components
of competence within a representative sample. A comparison
of competence components of Sample C and its pebbles
(Sample D) from Barrick Cortez gold mine is insightful as
24% increase in pebbles shows how the ExDWT data sheds
light on why variable ore types are exposed to characteristic
changes as processed through the circuit. This information
which could be used to customize circuit designs best to
the ore comminution characteristics for improved energy
efficiency.
It is acknowledged that the proportion of key compo-
nents within the fresh feed can vary—nonetheless simulat-
ing a range of scenarios including different proportions of
key competences should provide a basic, but helpful knowl-
edge of such a variation. The simulated scenarios imply that
the SAG mill performance is likely to be highly influenced
by the ore nature and the extent of ore-induced operational
variability. For this purpose, 13 scenarios were simulated to
explore the performance of SAG milling when introduced
to ore feeds with a range of competence components. The
simulation results at Jb=12.1% shows a throughput of
550 t/h for the actual ore composed of 24% hard, 43%
medium and 33% soft components while the at extreme
scenarios (100% hard and 100% soft) the throughput 452
t/h (–18%) and 792 t/h (+44%), indicating possible range
of changes induced by a multi-component ore and/or dif-
ferent ore blends. That is, the proposed breakage charac-
terisation, modeling and description approach could assist
in quantifying components of competence within sampled
ore feeds, and then exploring likely impact of the grind-
ing. Therefore a more effective integration of orebody
knowledge into evaluations should allow for quantifying a
more representative risk profile, particularly beneficial for
design and optimisation as well as addressing operational
bottlenecks during specific periods over the life-of-mine.
However, such an analysis will also require development
of sampling strategies which preserve the intrinsic degree
of variation within an ore type instead of reducing it by
blending. In addition to competence variability, particle
size distribution (PSD) variability can also have a signifi-
cant impact on mill performance (which is not with the
scope of this paper), especially the power balance between
SAG and ball mill—which is comprehensively explored
and documented in several mine-to-mill projects.
Ore feed variability presents simultaneous challenges
and opportunities. The degree to which its associated risks
can be unveiled before transforming into significant eco-
nomic losses over the life-of-mine (LOM) depends on how
detailed key sources of uncertainty are captured, described
and accounted in decision-making. In this regard, Smith et
al. (2022) explored the likely impact of applying a Mine-
to-Mill strategy on the asset value through Strategic Mine
Planning (SMP), which offers the assessment and ranking
of improvement strategies over the life of the mine (namely,
Strategic Mine-to-Mill). Their results for a copper deposit
indicated a potential improvement of 7.9% in Net Present
Value (NPV) would be achievable over the LOM through
value-driven drill-and-blast practices. Faramarzi and Smith
(2023) later established Integrated Strategic Mine Planning
(I-SMP) which allowed for simulating the strategic impact
of blast fragmentation and ore competence variability on
NPV over the LOM. As a future work, the I-SMP com-
bined with proposed multi-component breakage modelling
and description approach in this paper aids in quantifying
how different components of competence within a deposit
may influence the asset value—therefore mining schedules
could be tuned to smooth out risks in certain periods—
which should establish a meaningful link between the min-
ing and milling plans and practices. Additionally, one of the
main risks of feed competence variation is the ability of SAG
mill to maintain the load. A survey is required for mapping
the results of the proposed multi-component modelling
and description approach into an integrated value-chain