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Mineral mapping techniques to optimize
downstream processing routes
Eric PIRARD
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ChemysteryWhat chemistry won’t tell you
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Chemystery
• What is this ?
o O 65 %
o C 18 %
o H 10 %
o N 3 %
o Ca 1,4 %
o P 1,1 %
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• The molecular base (nucleotides) of our DNA
o Adenine C5H5N5
o Thymine C5H6N2O2
o Cytosine C4H5N3O
o Guamine C5H5N5O
MOLECULAR BIOLOGY
...not so much a technique as an approach
… with the leading idea of searching below the large-
scale manifestations of classical biology…
© Wikipedia
Our body
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Our body
• The Human Genomeo 22 000 genes
o 3,4 billion pairs of nucleotides
Total cost of sequencing a human genome over
time as calculated by the NHGRI
DNA sequencing is the process of
determining the precise order
of nucleotides within a DNA molecule.
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OrebodiesChoosing the right perspective
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The Geologist’s Orebody
• Exploring the pasto Geology & Tectonics
• Regional,…
• Local,…
o Fluids
• Compositions,…
• P,T,…
o Petrography
• Host rock,…
• Orebody,…
o Timing
• Mineral parageneses,…
• Alteration,…Burnotte, E, Pirard, E, & Michel, G. (1989). Genesis of gray monazites : evidences from the Paleozoïc of Belgium. Economic Geology, 84, 1417-1429
Massif de Stavelot (E.Belgium)
Cambrian-Ordovician
© B
RG
M
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The Economist’s Orebody
• Evaluating the presento Reserves
• Mt
• Grade
o Mine Planning
• Pit optimisation,…
• Infrastructure,…
• Blending, …
o Simulations
• Grade / tonnage curve
• Financial simulation
© Detour Gold
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The Metallurgist’s Orebody
• Anticipating the futureo Understand downstream processing / end use
o Identify useful features
• Mineralogy, …
• Porosity, fractures, …
o Quantify variability
• From deposit…
• … to grain scale
o Perform small scale tests
• Comminution, …
• Concentration,…
Jaimes Contreras, R. A, Pilawski, D, Califice, A, & Pirard, E. (2010). Quantitative MicrotextureAnalysis of Carbonate Rocks Using Bireflectance Imaging. Proceedings IAMG 2010
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Bridging the cross-discipline divide
The prime focus of
geometallurgy is bridging the
cross-discipline divide between
geology and mineral processing
There are many disciplines
involved in major mining
operations with potential
for significant disjoints….
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GeometallurgyEmbracing the view from mine to mill
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Geometallurgy : what we need
• Molecular Geologyo Fast and Accurate Mineral Identification
• Valuable Minerals
• Gangue Minerals
• Elemental Deportment
• Sequencing Oreso Fully Automated Quantitative Analysis
• Modal Analysis (% mass)
• Porosity and fractures
• Grain/Crystal size
• Grain shape
• Microtextures
• Predicting functionalityo Process Oriented Modelling - Indices
✓ Breakability, Floatability,…
✓ Leachability, Thermal expansion,…
Minerals Ores
Function
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Towards Molecular GeologyA need for mapping minerals
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A need for mapping minerals
• Do you perceive any difference?
O 35 %
Si 21 %
Al 11 %
Fe 6 %
Ni 1,5 %
Ga 27 ppm
Pb 15 ppm
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A need for mapping minerals
• 2,5Mt Ottoman slags in Küre (TK)
• Is it economical to recover Co ?o Under which form is Co ?
o How could we separate it from the rest ?
• Flotation, Gravity, Pyro/Hydrometallurgy,…
o Fe, Si and Al are shown as oxides (is this correct ?)
FeO 59.7 %
SiO2 23.5 %
Al203 11.6 %
S 1.8 %
Cu 0.76 %
Co 0.38 % !
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A need for mapping minerals
• ELEMENTAL DEPORTMENT
A low flotation recovery (92.6% cobalt remained in the tailings) of cobalt was
probably due to the formation of non-floatable cobalt spinels and silicates in the slag
… Cobalt was leached with an 86.5% dissolution efficiency at a roasting temperature
of 500°C, a roasting time of one hour and a pyrite:slag ratio of 3:1.
(Bulut et al., 2006)
Pirard, E. (1991), Quantitative mineralogical analysis of Cobalt and Copper distribution in historical slags from Küre (Turkey), CIM Bulletin, v84, 87-91
Quantitative Image Analysis
+ Microprobe
Fayalite Fe2SiO4
Wüstite FeO
« Pyrrhotite » FeS
Cu Sulphides
« Glass »
Hercynite Fe Al2O4
Reflected Light Optical Microscopy
of a polished block of slag
Cobalt Deportment in the slag
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A need for mapping minerals
• Geometallurgical modelling of orebodieso Towards a Mineralogical Information System (MIS)
© GOCAD
HyperspectralCore-Scanning
Microscopical Imaging
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Towards Molecular GeologyPrinciples of Mineralogical Imaging
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Principles of Mineralogical Imaging
• 3S : Source-Sample-Sensor
Source
Emission of a given
electromagnetic
spectrum
Sensor
Material with a specific
capability to convert photons
into electrons (Quantum
Efficiency)
Target object with
specific surface properties
Sample
Target specific response in terms of light
reflection, diffusion, absorption, fluorescence,
back-scattering, etc.
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Principles of Mineralogical Imaging
• Punctual Scanning Modeo 2D Scanning beam
• Beam spot size (µm)
• Scanning speed (µm/s -> m/s)
• Sensitivity of sensor (integration time) (ms)
Necessary compromise between
spectral/spatial resolution
© Z
eis
s
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Principles of Mineralogical Imaging
• Backscattered Electrons Imaging (BSE)
• Energy Dispersive X-Ray Imaging (EDX)
© Z
eis
s
Hercynitefrom FeO.Al2O3 to 5FeO.3Al2O3
LeuciteKAlSi2O6
Al
Fe
Si
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Principles of Mineralogical Imaging
• From elements to minerals
© B Tordoff – Zeiss (2016)
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Principles of Mineralogical Imaging
• Line Scanning Modeo Linear sensor
• typ. 2000 – 8000 pixels for video
o Sample translation (conveyor, tray,…)
• horizontal resolution : optical
• vertical resolution : mechanical
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Principles of Mineralogical Imaging
• Core-Scanning Prototypeo Visible to Near Infrared: 400 - 1000 nm
o Short Wave Infrared: 1000 - 2500 nm
o Resolution VNIR: 30 pixels/cm (300 µm)
o Resolution SWIR: 10 pixels/cm (100 µm)
(Barnabé et al. 2015)
DMT, leader
ULiege – GeMMe
Fraunhofer EZRT; BGR; GTK
LTB; Bachmann; ; U Paris Sud; Eramet; MATSA
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Principles of Mineralogical Imaging
• Area scano Staring array
• typ. 1 – 14Mpixels for (still) video
o No mechanical movement
o Resolution fixed by sensor
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Principles of Mineralogical Imaging
• MultiSpectral Imaging in Reflected Light Microscopy
Criddle & Stanley QDFIII, 1993
Califice A. (2008)
AMCO
Automated Microscopic Characterization of Ores
UPM Politecnica de Madrid
Uliege - GeMMe
TSL Labs
First Quantum (CLC) - KGHM
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Towards Sequencing OresProcess Oriented Characterization
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Modal Analysis : PP=AA=VV
• Stopping criterion for Modal Analysis from random sections of particleso Based on Gy’s theory (Califice et al., 2012)
EF S
dC 2
952 '.=
C’ : « ore constant »d95 : max particle sizeSE : total surface to analyze
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Modal Analysis : PP=AA=VV
• Stopping criterion for Modal Analysis from random sections of particleso Based on Gy’s theory (Califice et al., 2012)
Average pyrite grade after analysing 150 images
Confidence Interval for pyrite
grade after analysing 150 images
Py %
Nb
Histogram of pyrite area fractionsin 250 images.
Estimation of Pyrite area fraction from a well-liberated 9% Pyrite mix
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Modal Analysis : PP=AA=VV
• Modal Analysis of Concentrate vs Tailing
o Operator 1 : 1h-2h analysis, short dwell time
o Operator 2 : 5h-6h analysis, double dwell time
ICP AUTOMINERALOGY% Fe (ICP) % Cu (ICP) Nb particles Fe (Mineralogy) Error Cu (Mineralogy) Error
CONC +75 34,06 26,02 601 32,7 4% 26,6 2%
CONC +38 32,73 24,76 2624 30,4 7% 27,9 13%
TAIL +75 2,52 0,11 98 47,7 1792% 4,7 4206%
TAIL +38 2,43 0,09 369 50,1 1963% 2,2 2359%
ICP AUTOMINERALOGY% Fe (ICP) % Cu (ICP) Nb particles Fe (Mineralogy) Error Cu (Mineralogy) Error
CONC +75 34,06 26,02 2755 31,83 7% 27,31 5%
CONC +38 32,73 24,76 2173 30,13 8% 28,64 15%
TAIL +75 2,52 0,11 2497 3,71 47% 0,17 53%
TAIL +38 2,43 0,09 2406 3,80 57% 0,06 30%
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Modal Analysis : PP=AA=VV
• Using Chemical Assays for Cross-Validationo Element to Mineral Conversion
o Modal Analysis adjusted to Chemical Analysis
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Particle Size Analysis
• 3D from 2D sections is tricky (Wicksell problem)o Equivalent square diagonal (Petruk) or Equivalent disk diameter are often used as “size”
• Touching particles (!)
𝐷3𝐷 = 2. 𝐴 𝑋
Image of random sections from a narrow-sized galena mix
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Particle Size Analysis
• Prepare sized fractionso Measure “maximal inscribed disk” of only the largest particles (P75) particles
• Indicator correlated to thickness (dissolution time),…
DIN
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Liberation Analysis
• 3D liberation analysis from 2D sections is « crazy » (King; Schneider; Barbery; Gay ;…)
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Liberation Analysis
o Work on sized fractions
o Limit liberation analysis to only the « largest » particles
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Beyond liberation… texture
• Advanced Textural Indiceso Intercept based indices instead of areal liberation
12.4%
66.4%
11.9% 1.9%5.1%
2.3%
Liberated Chalcopyrite
Chalcopyrite in Simple Intergrowth
Matrix crossed by Stockwork
Inclusion coated by a rim or semi-rim
Not Classified
Coated and crossed by Stockwork
Perez Barnuevo L., Pirard E. and Castroviejo R. (2013) ‘Automated characterisation of intergrowth textures in mineral particles: a case study’, Minerals Engineering, 52, pp. 136–142
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Beyond liberation… texture
• Advanced Textural Indiceso Intercept based indices instead of areal liberation
𝐿𝛼 =𝐴(𝛼)
𝐴(𝑋)= 54%
=
i
i
i
i
VL
N
S
)(
2)(
Breakability
=
)0,(2
)0,(i
iNd
B
Floatability
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Towards predicting functionalityProcess Oriented Modelling
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Process Oriented Modelling
• Quantitative Analysiso Modal mineralogy
o Porosity and fractures
o Crystal / Grain size
o Grain shape
o Mineral connexity
BreakabilityMagnetic
susceptibility
Floatability
Sinterability
MINERALOGICAL MAPPING
PROGNOSTIC MINERALOGY
Leachability
Chalcopyrite
Stannite
Sphalerite
Pyrite
Quartz
Al-Si
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Process Oriented Modelling
• Mineral Intelligenceo Need for databases with physical properties of minerals/phases
• Density
• Hardness
• Magnetic Susceptibility
• Resistivity
• Dielectric Constant
• Hydrophobicity
• Thermal resistance
• Mechanical resistance
• Etc…
HSC GEO Mineral Database © Outotec
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Process Oriented Modelling
• Particle Tracking in process simulationo Lamberg & Vianna, 2007
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ConclusionsStill a long way to go…
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Conclusion
• 3 steps roadmap towards a More Automated Mineralogy
MINERALS
INTELLIGENCE
II
RoxelsParticulate Systems
AnalysisInteractive Graphics (EDA)
ROCKePEDIA
REPOSITORY
III
Cytomine PlatformRemote Image
AnnotationSmart Mineral Databases
ADVANCED
MINERAL
MAPPING
Correlative MicroscopyMultimodal SegmentationOptimal Sampling Strategy
I
Imaging Platforms
AnalyticalServices
Customers
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Join us @ MITL2020
• MINERALS IN THE LOOP Conference, World Tour, Dec 14-15, 2020