Dr. Johann Claassen February 2012 ROLE OF THE MINERALOGIST/GEOLOGIST IN OPTIMISING THE MINING VALUE...
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- Slide 1
- Dr. Johann Claassen February 2012 ROLE OF THE
MINERALOGIST/GEOLOGIST IN OPTIMISING THE MINING VALUE CHAIN
- Slide 2
- Content Future role of the mineralogist/geologist in the mining
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
- Slide 3
- Future role of the mineralogist/ geologist in the mining
environment Current reality: > 95% of trained
mineralogists/geologists work in the mining 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
- Slide 4
- 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
- Slide 5
- 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
- Slide 6
- 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 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)
- Slide 7
- Future role of the mineralogist/ geologist in the mining
environment
- Slide 8
- 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 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.
- Slide 9
- 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 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
- Slide 10
- Impact of variable mineralogy on downstream processes
- Slide 11
- Complex mineralogy (what is the impact on downstream
processes?) Bornite (Cu 5 FeS 4 ) Carrollite Co 2 CuS 4 ) Stannite
(Cu 2 SnFeS 4 ) Djurlite (Cu 1.96 S) Tennantite (Cu 12 As 4 S 13 )
Chalcocite (Cu 2 S) Pseudo-eutectic intergrowth between bornite and
carrollite (Mascott Mine, Drake, NSW) Paragenic sequence tennantite
through chalcopyrite, bornite and chalcocite (Mascott Mine, Drake,
NSW) Bornite (Cu 5 FeS 4 ) Chalcopyrite (CuFeS 2 ) Tennantite (Cu
12 As 4 S 13 ) Paragenic sequence tennantite/bornite/ chalcopyrite
and gold (Mascott Mine, Drake, NSW) Chalcopyrite (CuFeS 2 ) Bornite
(Cu 5 FeS 4 ) Gold Tennantite (Cu 12 As 4 S 13 ) Covellite
(CuS)
- Slide 12
- 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 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
- Slide 13
- 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
- Slide 14
- Impact of variable ore body geometry on downstream
processes
- Slide 15
- Orebody morphological factors Dolerite dyke
- Slide 16
- Ore and mineral treatment processes Ore body Market
GeologyMiningBeneficiation & Processing Logistics Physical
processes Aqueous processes High temp. processes Drilling Blasting
Loading Hauling Hydrometallurgical processes Pyrometallurgical
processes
- Slide 17
- Ore and mineral treatment processes Physical processing: Size
reduction: Crushing Grinding Milling 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) Bulk materials handling
(conveyance and storage) Waste treatment Solid-liquid separation
(thickening, filtration)
- Slide 18
- Ore and mineral treatment processes Aqueous solution processing
Separation processes: Leaching Precipitation Ion exchange Compound
formation: Crystallisation Chemical precipitation Metal production:
Cementation Gaseous reduction Chemical precipitation Electrowinning
Metal purification: Aqueous metal purification rarely done, focus
is on upstream processes to purify solutions and compounds
- Slide 19
- 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
- Slide 20
- Example: Zn metal production from Zn/Pb sulphide deposit
Crushing Milling PbS flotation ZnS flotation CONCENTRATE PRODUCTION
Zn METAL PRODUCTION Pb concentrate Zn concentrate (54% Zn) Tailings
Run-of-mine Zn metal Zn concentrate (54% Zn) As 2 O 3 Zn dust
- Slide 21
- Example: Zn metal production from Zn/Pb sulphide deposit
Processing stepGeological variablesPotential impact 1. Crushing
(3-stage) Hardness/grindabilityThroughput, 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
ZnCO 3 in dolomite, competing speciesLow 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), SiO
2, 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
- Slide 22
- Comments and Questions