ROLE OF THE MINERALOGIST/GEOLOGIST IN OPTIMISING THE MINING VALUE CHAIN

Dr. Johann ClaassenFebruary 2012ROLE OF THE MINERALOGIST/GEOLOGIST IN OPTIMISING THE MINING VALUE CHAIN

ContentFuture role of the mineralogist/geologist in the mining environmentHolistic approach to optimising the mining value chainImpact of geology on the performance of the mining value chainOre and mineral treatment processesExampleComments and questions

Future role of the mineralogist/ geologist in the mining environment Current reality:

> 95% of trained mineralogists/geologists work in the mining environmentGeologists are more familiar with the ore and orebody characteristics than any other person at a mining operationGeologists tend to function in silosRemaining reserves are more complex and variableShortage in skilled and experienced labourHigh volatility in labour marketMore 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 wealthSystem throughput driven focusIntegration of ore and ore body knowledge with downstream processing requirements and the marketsIntegration of different functional groups at mining operationsIntegration of the strategical and operational environments at a tactical levelMore 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 environmenttraining in ore and ore body morphology and how it impacts the mining value chaintraining 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 chaindevelop a better understanding of ore and mineral treatment processesdevelop 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 chainSystem focus:

End-to-end process viewIt is the system that generates a final product and not the different departments/stepsAlign 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 levelsKey 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 chainOre morphology:Refers to the physical and chemical properties of an oreIn the MRM context, the impact of ore morphology on the performance of downstream processes and the value of products produced are of interestThe 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 throughputMeso texture relationship between mineral type and texture (massive, banded and disseminated ores): affects upgrading potential of ore and throughputHead 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 throughputDeportment 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 chainOre morphology (cont):Competing species non-valuable minerals such as graphite, pyrite, carbonaceous materials interact with reagents: affects process efficiencies and the overall cost of operationsEffect of phyllosilicates: consume reagents: affects process efficiencies and the overall cost of operationsNon-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 throughputMineralogical transformation during leaching: secondary product formation that requires an adjustment of conditions to ensure optimal extraction of valuable elementsDevolatilisation 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 elementsVariation 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 qualityHardness 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 wasteSuperfines 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?)

Bornite(Cu5FeS4)CarrolliteCo2CuS4)Stannite(Cu2SnFeS4)Djurlite (Cu1.96S)Tennantite(Cu12As4S13)Chalcocite (Cu2S)Pseudo-eutectic intergrowth between bornite and carrollite (Mascott Mine, Drake, NSW)Paragenic sequence tennantite through chalcopyrite, bornite and chalcocite (Mascott Mine, Drake, NSW)Bornite(Cu5FeS4)Chalcopyrite(CuFeS2)Tennantite(Cu12As4S13)Paragenic sequence tennantite/bornite/ chalcopyrite and gold (Mascott Mine, Drake, NSW)Chalcopyrite(CuFeS2)Bornite(Cu5FeS4)GoldTennantite(Cu12As4S13)Covellite(CuS)Impact of geology on the performance of the mining value chainOre 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 operationsThe 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 generatedclosely 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 chainOre 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 TEMPOSTexture 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 RISKDolerite sills and dykes: lead to DILUTION and a reduction in loading TEMPOS

Impact of variable ore body geometry on downstream processesOrebody morphological factors

Dolerite dyke

Ore and mineral treatment processes

Ore bodyMarketGeologyMiningBeneficiation& ProcessingLogisticsPhysicalprocessesAqueousprocessesHigh temp.processesDrillingBlastingLoadingHaulingHydrometallurgicalprocessesPyrometallurgicalprocessesOre and mineral treatment processesPhysical processing:Size reduction:CrushingGrindingMilling

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 treatmentSolid-liquid separation (thickening, filtration)

Ore and mineral treatment processesAqueous solution processing

Separation processes:LeachingPrecipitationIon exchangeCompound formation:CrystallisationChemical precipitationMetal production:CementationGaseous reductionChemical precipitationElectrowinning

Metal purification:Aqueous metal purification rarely done, focus is on upstream processes to purify solutions and compounds

Ore and mineral treatment processesHigh temperature processingSeparation processesVapour phase separationChemical changes in the solid stateLiquid/gas separation

Compound formation

Metal productionFrom metal oxidesFrom metal sulphidesFrom metal halidesMetal purificationCompound formationVacuum refiningZone refining

Example: Zn metal production from Zn/Pb sulphide depositCrushingMillingPbS flotationZnS flotationCONCENTRATE PRODUCTIONZn METAL PRODUCTIONPb concentrateZn concentrate(54% Zn)TailingsRun-of-mineRoastingLeachingCo precipitationCd precipitationFe & Si precipitationZn electrowinningMeltingCastingZn metalZn concentrate(54% Zn)Mg and Mn removalAs2O3Zn dustZn dustExample: Zn metal production from Zn/Pb sulphide depositProcessing stepGeological variablesPotential impact1. Crushing (3-stage)Hardness/grindabilityThroughput, cost (liner plates)2. MillingMineral associations, element replacement, particle size, hardness/grindability

Under- and over milling, recovery losses, throughput, cost3. PbS flotationCompeting species (phyllosilicates)Reagent consumption, low recovery4. ZnS flotationZnCO3 in dolomite, competing speciesLow recovery, over-milling (fines losses, increased cost)5. RoastingElement replacement - Fe in Zn structure leads to Zn ferrite (spinel) formation); sulphates in concentrateSulphates increase electrolyte acidity require neutralisation which leads to Zn losses and increased cost (neutralisation agents)6. LeachingFe impurities in Zn concentrate due to process efficiency and mineral associationsFe precipitates cover ZnO particles, Zn-ferrites are difficult to leach, recovery losses, production losses7. Solution purificationCo 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 losses8. Zn electrowinningCo and Cd affects adherence of Zn metal to cathode plates, Mg and Mn levels in concentrate affect solution density, current efficiency and cathode qualityProduction loss of up to 1 week, high running cost9. Melting and castingImpurities in concentrates due to process efficiency, mineral associations and element replacementReagent consumption, final product out of specificationComments and Questions