XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 865
in feed quality. Geometallurgical relationships used in con-
junction with analyzer data for real time responses ensures
maximum recoveries are achieved for each ore type and
this can be further enhanced through digital twin applica-
tions. Elemental data can be used to derive non-measur-
able parameters such as ore hardness and used to moderate
mill feed rate to optimize throughput. Measurements of
acid-consuming gangue are used to control acid addition
at Sepon (Balzan et al., 2016). Patel (2014) discusses how
changes in lead-zinc ore feed quality to a dense medium
separation plant at Mount Isa Mines are used to modify
density cut points. Matthews and Du Toit (2011) discuss
the benefits in measuring beneficiation feed to predict
upgrade factors for iron ore types confirmed by analyzers
on jig product and discard flows.
High quality measurement data is suitable for ore rec-
onciliation to the mining schedule and block model. It rep-
resents actual ore quality supplied from the mine to the
process operation and has proven to be the most effective
way to determine the quality of mined material at numer-
ous mining operations. Matthews and Du Toit (2011) dis-
cuss the application of analyzer data, in conjunction with
belt weigher data, for elemental balance at Khumani iron
ore operations where all relevant conveyed flows, includ-
ing discard flows, are analyzed. Analyzer data for metal
accounting is beneficial in gold operations, where represen-
tative sampling of gold grade in mined ore is almost impos-
sible due to the high nugget effect present in plant feed.
Moisture Analysis
Material type and measurement precisions needed for effec-
tive control affect the suitability of moisture analysis tech-
niques for conveyed materials. Microwave transmission has
proven suitable for continuous free moisture measurement
in most mineral industry applications. Figure 4 shows a
typical microwave moisture analyzer. Materials that are
electrically conductive, highly magnetic, too dense, metals,
or contain water in solid form may require other techniques
such as fast neutron and gamma transmission for repre-
sentative moisture analysis. Microwave transmission uses
microwaves at frequencies in the hundreds of MHz or low
GHz ranges at low power to penetrate conveyed flows and
is non-hazardous. The dielectric constant of water (about
80) is an order of magnitude higher than for most minerals
and therefore free moisture responds differently in the sys-
tem to mineral matter. Attenuation and group delay (phase
shift) of the microwave field are measured to determine
free moisture content in the flow instantaneously and con-
tinuously. Effective calibration methods allow high mois-
ture measurement precisions of typically better than 0.5%
moisture in most materials with precisions as low as 0.05%
moisture achieved in some materials. If inherent moisture
content is known then total moisture can be calculated for
the material as well. The digital calibration is very stable
and frequent recalibration is largely unnecessary.
Free moisture is measured to:
• Control dust extinguishment levels in conveyed flows
• Allow dry tons calculation for ore reconciliation,
metal accounting and permitting compliance
• Identify potential material handling problems if too
sticky to prevent blockages, damage and downtime
• Optimize dewatering (drying, filtration) processes to
control energy consumption and cycle times
Source: Scantech International Pty Ltd
Figure 4. A TBM200 Series microwave moisture analyzer used for free moisture analysis on conveyed flows
in feed quality. Geometallurgical relationships used in con-
junction with analyzer data for real time responses ensures
maximum recoveries are achieved for each ore type and
this can be further enhanced through digital twin applica-
tions. Elemental data can be used to derive non-measur-
able parameters such as ore hardness and used to moderate
mill feed rate to optimize throughput. Measurements of
acid-consuming gangue are used to control acid addition
at Sepon (Balzan et al., 2016). Patel (2014) discusses how
changes in lead-zinc ore feed quality to a dense medium
separation plant at Mount Isa Mines are used to modify
density cut points. Matthews and Du Toit (2011) discuss
the benefits in measuring beneficiation feed to predict
upgrade factors for iron ore types confirmed by analyzers
on jig product and discard flows.
High quality measurement data is suitable for ore rec-
onciliation to the mining schedule and block model. It rep-
resents actual ore quality supplied from the mine to the
process operation and has proven to be the most effective
way to determine the quality of mined material at numer-
ous mining operations. Matthews and Du Toit (2011) dis-
cuss the application of analyzer data, in conjunction with
belt weigher data, for elemental balance at Khumani iron
ore operations where all relevant conveyed flows, includ-
ing discard flows, are analyzed. Analyzer data for metal
accounting is beneficial in gold operations, where represen-
tative sampling of gold grade in mined ore is almost impos-
sible due to the high nugget effect present in plant feed.
Moisture Analysis
Material type and measurement precisions needed for effec-
tive control affect the suitability of moisture analysis tech-
niques for conveyed materials. Microwave transmission has
proven suitable for continuous free moisture measurement
in most mineral industry applications. Figure 4 shows a
typical microwave moisture analyzer. Materials that are
electrically conductive, highly magnetic, too dense, metals,
or contain water in solid form may require other techniques
such as fast neutron and gamma transmission for repre-
sentative moisture analysis. Microwave transmission uses
microwaves at frequencies in the hundreds of MHz or low
GHz ranges at low power to penetrate conveyed flows and
is non-hazardous. The dielectric constant of water (about
80) is an order of magnitude higher than for most minerals
and therefore free moisture responds differently in the sys-
tem to mineral matter. Attenuation and group delay (phase
shift) of the microwave field are measured to determine
free moisture content in the flow instantaneously and con-
tinuously. Effective calibration methods allow high mois-
ture measurement precisions of typically better than 0.5%
moisture in most materials with precisions as low as 0.05%
moisture achieved in some materials. If inherent moisture
content is known then total moisture can be calculated for
the material as well. The digital calibration is very stable
and frequent recalibration is largely unnecessary.
Free moisture is measured to:
• Control dust extinguishment levels in conveyed flows
• Allow dry tons calculation for ore reconciliation,
metal accounting and permitting compliance
• Identify potential material handling problems if too
sticky to prevent blockages, damage and downtime
• Optimize dewatering (drying, filtration) processes to
control energy consumption and cycle times
Source: Scantech International Pty Ltd
Figure 4. A TBM200 Series microwave moisture analyzer used for free moisture analysis on conveyed flows