ROLE OF THE MINERALOGIST/GEOLOGIST IN OPTIMISING
THE MINING VALUE CHAIN
Dr. Johann Claassen
February 2012
Content
 Future role of the mineralogist/geologist in the mining
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environment
Holistic approach to optimising the mining value chain
Impact of geology on the performance of the mining value
chain
Ore and mineral treatment processes
Example
Comments and questions
Future role of the mineralogist/
geologist in the mining environment
 Current reality:
 > 95% of trained mineralogists/geologists work in the mining
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environment
Geologists are more familiar with the ore and orebody characteristics
than any other person at a mining operation
Geologists tend to function in silos
Remaining reserves are more complex and variable
Shortage in skilled and experienced labour
High volatility in labour market
More intense regulation of natural resources
Future role of the mineralogist/
geologist in the mining environment
 Future requirements:
 Sustainable exploitation of complex reserves(high variability) –
find more effective and efficient ways to exploit mineral wealth
 System throughput driven focus
 Integration of ore and ore body knowledge with downstream
processing requirements and the markets
 Integration of different functional groups at mining operations
 Integration of the strategical and operational environments at a
tactical level
 More productive labour force
Future role of the mineralogist/
geologist in the mining environment
 How to close the gap?:
 Geologists take the lead in:
 integration of knowledge and functional areas in the mining environment
 training in ore and ore body morphology and how it impacts the mining value
chain
 training in mineral resource utilization principles (MRM)
 finding new ways to exploit complex mineral resources by working together
with other disciplines (e.g.Geometallurgy)
 Geologists to:
 have a clear understanding of their role in optimising and STABILISING the
mining value chain
 develop a better understanding of ore and mineral treatment processes
 develop a good understanding of MRM/material flow principles and how it
affects the output of mining systems; TAKE A HOLISTIC APPROACH
TOWARDS MANAGING THE MINING VALUE CHAIN
Holistic approach towards optimising
the mining value chain
 System focus:
 End-to-end process view
 It is the system that generates a final product and not the different
departments/steps
 Align ore with the market requirements (pit to product principle)
 Manage throughput of the system:
 flow of material or information through the value chain (“Flow world” vs
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“mechanistic/accounting” approach)
physical constraints and payable throughput attributes (impact of material
characteristics on downstream processes and product value)
Dependencies and inter-dependencies
Stability of the system as a whole (very important due to variability in the ore
and ore body morphology)
Buffer levels
Key value drivers (very often geology related, 80-20 principle)
Future role of the mineralogist/
geologist in the mining environment
Impact of geology on the performance
of the mining value chain
 Ore morphology:
 Refers to the physical and chemical properties of an ore
 In the MRM context, the impact of ore morphology on the performance of
downstream processes and the value of products produced are of interest
 The mineralogist/geologist is well positioned to advise a mining company on the
physical and chemical characteristics of an orebody.
 Ore morphological characteristics and its impact:
 Micro texture – relationship between grain size and intergrowth irrespective of the mineral
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type: affects liberation potential of minerals and throughput
Meso texture – relationship between mineral type and texture (massive, banded and
disseminated ores): affects upgrading potential of ore and throughput
Head grade: overlaps between different meso-textures may exist which could affect
recovery if blending of ROM is not handled correctly. Grade-recovery conflict to be fully
understood.
Grindability: refer to the hardness of rock: affects recovery of valuable minerals when
over/under grinded/liberated and throughput
Deportment of valuable elements – refers to the way in which elements occur in the ore
and it includes the genesis of the ore or mineral: affects mainly recovery of elements in
hydro- and pyrometallurgical processes.
Purity of the mineral crystal structure: displacement of elements in crystal
structures/weathering effects, devolatilisation of coal: mainly affects mineral properties,
which in turn affects the efficiency of beneficiation-, hydro- and pyrometallurgical
processes. Precipitation of unwanted elements could adversely affect the performance of
these processes.
Impact of geology on the performance
of the mining value chain
 Ore morphology (cont):
 Competing species – non-valuable minerals such as graphite, pyrite, carbonaceous materials
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interact with reagents: affects process efficiencies and the overall cost of operations
Effect of phyllosilicates: consume reagents: affects process efficiencies and the overall cost of
operations
Non-recoverable valuable minerals or elements – unliberated grains and elements in oxides
or carbonates cannot be recovered during beneficiation (zinc in dolomite, reaction products
coating particles during hydro- and pyrometallurgical processes): affects recovery and
throughput
Mineralogical transformation during leaching: secondary product formation that requires an
adjustment of conditions to ensure optimal extraction of valuable elements
Devolatilisation effects – coal devolatilised because of dolerite activity: increased
weathering and coal porosity that could influence recovery and reagent consumption
(floatation)
Weathering effects – oxidation and hydration of minerals that affects mineral surface
composition: affects mainly recovery of minerals and elements
Variation in RD – in-situ ore density variations: high levels of near-dense material will
affect plant efficiency and throughput. MATERIAL COMPATIBILITY in dense medium
separation processes could play a significant role in the performance of these processes and
final product quality
Hardness and porosity: porosity may reduce the SG of ores to such an extend that waste
material become near density material; difficult to separate ore and waste
Superfines – particles less than about 500micron: affects viscosity of dense media which in
turn impacts recovery of minerals/ores
Impact of variable
mineralogy on downstream processes
Complex mineralogy (what is the impact on downstream processes?)
Paragenic sequence tennantite through
chalcopyrite, bornite and chalcocite (Mascott
Mine, Drake, NSW)
Pseudo-eutectic intergrowth between bornite
and carrollite (Mascott Mine, Drake, NSW)
Bornite
(Cu5FeS4)
Chalcocite
(Cu2S)
Djurlite
(Cu1.96S)
Stannite
(Cu2SnFeS4)
Chalcopyrite
(CuFeS2)
Carrollite
Co2CuS4)
Tennantite
(Cu12As4S13)
Tennantite
(Cu12As4S13)
Paragenic sequence tennantite/bornite/
chalcopyrite and gold (Mascott Mine, Drake,
NSW)
Bornite
(Cu5FeS4)
Gold
Covellite
(CuS)
Chalcopyrite
(CuFeS2)
Tennantite
(Cu12As4S13)
Bornite
(Cu5FeS4)
Impact of geology on the performance
of the mining value chain
 Ore body morphology (geometry):
 Ore body geometry is a result of deposit style, host rock distribution and
subsequent deformation. It impacts MINING CONDITIONS directly.
Mining equipment selection and mining infrastructure development are to a
large extend influenced by the ore body geometry.
 VARIABILITY in ore body morphology disrupts mining operations
 The use of average norms and standards to plan and measure mining
performance destabilises the mining value chain where variability in ore
body geometry is present
 Geologists need to:
 ensure that adequate data is gathered that not only describes the quality of an ore body
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but also the geometry (geophysics)
ensure that mining standards developed (load tempo, drill tempo, etc) are
conditionally driven (CDS)
be wary of changes in ore body morphology from one area to the next (do not
extrapolate data or logic to new areas)
understand the impact that composite sampling may have on the quality of the data and
geological model generated
closely interact with mining operations during mining of complex ore bodies/seams
(coal, iron ore, gold, Merensky reef)
be wary of the impact that BLENDS may have on the performance of plant processes
Impact of geology on the performance
of the mining value chain
 Ore body morphology (cont.):
 Ore body morphological characteristics and its impact:
 Gradient/dip of an ore body/seams (incl. hanging and footwalls): mining equipment
functions optimally in a horizontal plane and mining at gradients in excess of 8˚ cause
DILUTION and lower THROUGHPUT (be wary of the use of average norms and
standards for planning and equipment selection)
 Thickness of seams (ore and watse): variability in seam thickness leads to DILUTION,
poor ORE EXTRACTION EFFICIENCIES and a reduction in mining TEMPOS
 Texture – joints, faults and fractures (areas of discontinuity): influences competence
and position of material/seams that may lead to DILUTION, a reduction in loading
TEMPOS and an increased SAFETY RISK
 Dolerite sills and dykes: lead to DILUTION and a reduction in loading TEMPOS
Impact of variable
ore body geometry on downstream processes
Orebody morphological factors
Dolerite
dyke
X Shale
Contact
Low Vol <13%
Lean Coal 13%< Vol <18%
Low Vol
Contact
Med Vol >18%
Lean Coal
Contact
8m
Section 2
18 m
Eskom
O Shale
Ore and mineral treatment processes
Ore body
Market
Geology
Mining
Beneficiation
& Processing
Logistics
Drilling
Blasting
Loading
Hauling
Physical
processes
Aqueous
processes
Hydrometallurgical
processes
High temp.
processes
Pyrometallurgical
processes
Ore and mineral treatment processes
 Physical processing:
 Size reduction:
 Crushing
 Grinding
 Milling
MAG. SEP
FILTER PRESS
Plant Feed
PRE-WASH
SCREEN
DRUM
PROD
DISC
ROLL
CRUSHER
SPIRALS
CC
FC
PPS
PROD
DISC
PROD
DISC
PROD
DISC
PPS
Disc Conv
CC Prod. Conv
 Particle selection:
 Based on size (screening)
 Based on density (aqueous, dense medium, pneumatic)
 Based on magnetic properties (magnetic separation)
 Based on electrical properties (electrostatic precipitation)
 Based on surface chemistry properties (floatation)
FC Prod. Conv
SPIRAL
PROD CONV
CM
DIL
 Bulk materials handling (conveyance and storage)
 Waste treatment
 Solid-liquid separation (thickening, filtration)
CM
DIL
CM
DIL
THICKENER
Ore and mineral treatment processes
 Aqueous solution processing
Small Cathodes
 Separation processes:
 Leaching
 Precipitation
 Ion exchange
 Compound formation:
 Crystallisation
 Chemical precipitation
 Metal production:
 Cementation
 Gaseous reduction
 Chemical precipitation
 Electrowinning
Manual Stripping
Neutral
Leach
Zinc
Dust
Calcine
Concs
STORAGE
``
ROASTER
Pure
solution
Impure
solution
ELECTROLYSIS
PURIFICATION
LEACH
2 Units total 540t/d
Cathodes
Double Contact
Residue
2 Stage
Hot Acid
SO
ACID
2
Paragoethite
Solution
PLANT
INDUCTION
LEACH
Sulphuric Acid
MELTING
2 Linear Machines 25kg
Pb/Ag Residue
IRON REMOVAL
2 Membrane
Paragoethite
CASTING
Jumbo caster (1
&2 tons)
Pb/Ag
ACID
DRUM
FILTER
FILTER
PRESS
HG, SHG &
ALLOYS
STORAGE
RAIL
ACID FOR SALE
RESIDUE
STORAGE
Cd, Cu & Co CAKE
STOCKPILE
 Metal purification:
 Aqueous metal purification rarely done, focus is on upstream processes to
purify solutions and compounds
METAL FOR SALE
Ore and mineral treatment processes
 High temperature processing
 Separation processes
 Vapour phase separation
 Chemical changes in the solid state
 Liquid/gas separation
 Compound formation
 Metal production
 From metal oxides
 From metal sulphides
 From metal halides
 Metal purification
 Compound formation
 Vacuum refining
 Zone refining
Example: Zn metal production from Zn/Pb sulphide deposit
CONCENTRATE PRODUCTION
Zn METAL PRODUCTION
Zn concentrate
(54% Zn)
Run-of-mine
Crushing
Milling
As2O3
PbS flotation
Pb concentrate
Zn dust
Zn dust
ZnS flotation
Tailings
Zn concentrate
(54% Zn)
Zn metal
Example: Zn metal production from
Zn/Pb sulphide deposit
Processing step
Geological variables
Potential impact
1. Crushing (3-stage)
Hardness/grindability
Throughput, cost (liner plates)
2. Milling
Mineral associations, element replacement, particle
size, hardness/grindability
Under- and over milling, recovery losses,
throughput, cost
3. PbS flotation
Competing species (phyllosilicates)
Reagent consumption, low recovery
4. ZnS flotation
ZnCO3 in dolomite, competing species
Low recovery, over-milling (fines losses, increased
cost)
5. Roasting
Element replacement - Fe in Zn structure leads to
Zn ferrite (spinel) formation); sulphates in
concentrate
Sulphates increase electrolyte acidity – require
neutralisation which leads to Zn losses and increased
cost (neutralisation agents)
6. Leaching
Fe impurities in Zn concentrate due to process
efficiency and mineral associations
Fe precipitates cover ZnO particles, Zn-ferrites are
difficult to leach, recovery losses, production losses
7. Solution purification
Co and Cd impurities in Zn concentrate (solid
solution and intergrowth), SiO2 , Fe
Reagent consumption (arsenic oxide), production
loss if Co ends up in cell house, Silica gels blind
filters – throughput and recovery losses, amorphous
Fe phases leads to Zn recovery losses
8. Zn electrowinning
Co and Cd affects adherence of Zn metal to cathode
plates, Mg and Mn levels in concentrate affect
solution density, current efficiency and cathode
quality
Production loss of up to 1 week, high running cost
9. Melting and casting
Impurities in concentrates due to process efficiency,
mineral associations and element replacement
Reagent consumption, final product out of
specification
Comments and Questions