Post on 18-May-2020
transcript
FINES CIRCUIT DESIGN AND PERFORMANCE
ENHANCEMENT ELEMENTS IMPACT ON PRODUCT VIU
Presentation SummaryOverview of Fine Circuit challengesOverview of Fine Circuit challenges …Fines Circuit design data generation …
o Sample treat techniques and data repairp q po Analytical loss attribution impactso Laboratory flotation data challenges
Design and Performance considerationsDesign and Performance considerations …o Factor affecting design and performanceo Recirculating frother exampleo Recirculating slimes product quality impacto Bottom size selection aspects
Value in Use ImpactsValue in Use Impacts …o Coking coal scenarioo Thermal coal scenario
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Fines Circuit Challenges Overview
Historical Discarding of Excess Fines
• Maintaining
Issues & Problems in Fines Processing
• Inadequate fines
Solutions & Rewards from Fines Processing
• Borecore pre‐gexpected throughput
• Avoiding penalties• Inadequate b fi i ti
Inadequate fines circuit design
• Insufficient or incorrectly pre‐t t d d i d t
Borecore pretreatment procedures & fines loss attribution Fl h t d ibeneficiation
technologies• Achieving (budget) production targets
treated design data• Throughput bottlenecks, avoidable coal
• Flowsheet design considerations
• Evaluation of all resource data and production targets
losses, dewatering issues, etc.
• Product handling, contract al penalties
product options• Total plant design value addinglcontractual penalties • Value assessment
models (Value in Use linkages)
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Fines Circuit Design Data Generation Aspects
Fines Circuit Design Data GenerationGeneration
Crushed Drill Core Data ‐generates an unnatural liberation state (not
representative of run‐of‐
Applying Liberation and Circuit Segregation Models
to Crushed Data can transform it into “pseudo”representative of run of
mine coal)transform it into pseudo pre‐treated washability data
B t ti i f lBest practice is for samples to be “drop‐shattered” with
“wet pre‐treatment “ (simulates natural breakage occurring during mining /
This is the only reliable way to deliver realistic data from borecores to model fines
circuit yield and ashoccurring during mining / CPP operations)
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Fi ti l l l t d i l b t t t t
Analytical Loss Attribution Aspects• Fine particles are commonly lost during laboratory pre‐treatment processes.• Important to attribute laboratory processing losses correctly to deliver
accurate data for design the fine coal circuit.
Loss Occurring
Determine ARD
Drop / shatter 20 times.Dry size @ 31.5mm
Loss Occurring
L
Hand Knap/Size Adjust to pass 31.5mm.
y @
Loss Occurring
RSD RSD
Dry Size @ 16.0mm, 8.0mm, 4.0mm and 2.0mm.
1/4 3/4
Loss Occurring
Raw Coal Analysis
Wet Tumble for 5 Minutes with cubes. Wet Size @ 16.0, 4.0, 2.0,
0.250 and 0.125mm
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Under‐Estimating Fines GenerationIt is very important to carry laboratory processing losses across all pre‐treatment phases to correctly model the proportion that will report to the fine coal circuit.
Generation of samples with a
1234samples with a representative plant feed size distributioncan only be
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can only be carried out with drill‐
cores via the application of
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15 15Perc
ent U
nder
size
application of pre‐treatment tests, such as drop shatter and wet
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Loss Corrected Wet Tumble Size
I d t L C t d Aft W t T bl and wet‐tumble testing.1 1
0.01 0.1 1 10 100
Size (mm)
Inadequate Loss Corrected After Wet-Tumble
Dry Sizing
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Lab Scale Flotation Data Challenges
N l i l b l fl i d• Non‐selective lab scale flotation data over states ash.
• Need actual representative sample for CCComps.• Need realistic yield / ash data for plant design• Need realistic yield / ash data for plant design envelopes.
• Lab scale column cells offers reliable pathways to resolve these challenges.
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resolve these challenges.
Fines Circuit Design and fPerformance Aspects
Some Factors Affecting Fines Circuit PerformancePerformance OptimisationFines Circuit Design Aspects
• Frother recirculation (Use of il bl t t )
Performance Optimisation Influences
• Slimes recirculation (Cl ifi ti ffi i davailable water streams)
• Slimes recirculation (Selection of stream direction and water balance)
(Classification efficiency and water clarity issues)
• Optimum feed presentation (Desliming efficiency andbalance)
• Optimum feed presentation (Desliming and loading)
• Upstream and down stream
(Desliming efficiency and volume / solids stability)
• Misplacement of coarse particles (Classification Upst ea a d do st ea
unit capacities• Fit for purpose beneficiation and dewatering equipment
efficiency issues)
• Bottom size selection (to maximise yield and quality)
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• Correct frother recirculation uses available froth laden water streams
Recirculating Frother Example
DeslimingCyclone
within the flotation circuit where possible.• Enables maximum ‘effective’ frother dosage rates.
‐0.250mm
‐1.4wwmm
DeslimingScreenUnderflow
g y
HBFd
Jameson Cell
‐1.4ww+0.250mm
Sieve Bend
TailingsThickener
Product
HBF Filtrate
Spirals
Frother Laden StreamFlotation Feed Sump
Tailings
Reject Product
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• Limited ability to beneficiate the ‐100m material, slimes component f ll fl h h h l
Recirculating Slimes Product Quality Impact
follows water flows throughout the plant.• Figure illustrates inability of a typical TBS (or Spiral) to successfully
beneficiate particles <100m in size.CUMULATIVE ASH by PARTICLE SIZE
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Minimal difference in cumulative ash between feed and product
40
50
60
tive
Ash
(%
Teeter Bed Feed
Teeter Bed Product
ash between feed and product streams for particles < 100mm
10
20
30
Cum
ulat Teeter Bed Product
0
10
0.01 0.10 1.00 10.00
GMS Particle Size (mm)
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Common Device Advantages Disadvantages
Some Fines Dewatering Comparisons
Rotary Vacuum Horizontal Belt Filter
(HBF)Dewaters all size fractions Moderate capital and operating costs
Higher TM in cakes
Hyperbaric Disc Filter Dryer cake moistureDe aters all si e fractions Higher capital and operating costsyp Dewaters all size fractions g p p g
Screen ‐bowl Centrifuge (SBC)
Dryer cake moistureLower capital costs
Does not dewater ‐0.030mm materialTreatment of effluent required
New Dewatering Technologies? TBC… TBC…
Coal thickeners
Maintains thickened feed to dewatering devices Affected by performance of dewatering devices
High capital costCoal thickeners Can handle significant fluctuation in flotation response
High capital costFlocculant dependant
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Bottom Size Selection ImpactsProduct CV (nar) vs Estimated Revenue per ROM tonneProduct CV (nar) vs. Estimated Revenue per ROM tonne
800.5mm Bottom Size (DMC & Spirals)
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75
OM
tonn
e)
0.35mm Bottom Size (DMC & Spirals)
0.25mm Bottom Size (DMC & Spirals)
65
ue (A
UD
$/R
O
0.125mm Bottom Size (DMC & Spirals)
60
Rev
enu
0.063mm Bottom Size (DMC & Spirals)
Deslimed Flotation -0.25+0.038mm(DMC Spirals & Flotation)
5521.5 22.0 22.5 23.0 23.5 24.0 24.5
Product CVnar (MJ/kg)
(DMC, Spirals & Flotation)
Deslimed Flotation -0.125+0.038mm(DMS, Spirals & Flotation)
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Product CVnar (MJ/kg)
Value in Use Impacts
• NOTE: Higher quality product doesn’t always deliver the best whole of resource revenue position…o Due to such factors as relative customer location and coal price
able to be realisedo This assessment is intended to provide insight into VIU impacts p g p
from coal quality variations only and may not be the optimum whole of resource outcome
Coal Quality Improvement – Coking CoalP t ti l C ki C l I t• Potential Coking Coal Improvements– CSN Increase ≈1.0– Vitrinite Increase ≈ 10 %– Ash Reduction ≈ 0.8%
• Coal quality improvements can significantly affect market position
i t ld t d d ki lagainst world traded coking coals– Position of coal has improved compared to
world traded coals
• Improving CSN and vitrinite improve• Improving CSN and vitrinite improve coke quality
• Lower ash product will allow blending with higher ash coals which will benefitwith higher ash coals which will benefit customers
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Utilisation – Impact on Coke Quality• CSR is an important• CSR is an important
parameter in the assessment of value of coke
• CSR can increase if coalCSR can increase if coal quality is improved
• Improvement in CSR has allowed the SSCC to be classified as SHCC
• A significantly greater number of coals satisfy SSCC constraints than SHCC (SSCCconstraints than SHCC (SSCC market more competitive)
• However, various grading of coking coals are used butcoking coals are used but there are no universally accepted suite of technical specifications
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Location of Steelworks
Coking Coal TradeEx 150Mt
• Large number of coals can satisfy SSCC requirements• Consequently more competition in this space• Upgrade to SHCC Potentially larger number of potential
Ex 60MtEx 15‐33MtEx 2‐2.5MtIm 0‐2MtIm 2‐10MtIm 10‐50Mt • Upgrade to SHCC – Potentially larger number of potential
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Im 50 Mt+
Coking coal pricing• Pricing indices dependent on CSR• Pricing indices dependent on CSR• Platts coking coal indices highly
dependent on CSR• Increase in CSR may attract
US$1.5/t increase in price (2015 Platts model)
h l l ‘ l’• Higher value coals can ‘travel’ further and expand market share potentialCS di d• CSR predictor under development by GlobalCoal(Online Trading Company) which may result in stronger linkage tomay result in stronger linkage to product quality and CSR
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Coal Quality Improvement – Thermal Coal
P i l I• Potential Improvements– Calorific Value Increase ≈ 200kcal/kg– Ash Decrease ≈ 0.8%
• Coal quality improvements can significantly affect market position against world traded thermal coals
– Position of coal has improved for energy and ash as compared to competing coals
• Potential coal price improvement ≈ $2/t (A&B Mylec pricing model)
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Power Plant SuitabilityP l t h l d i• Power plants have coal design specifications.– E.g. CV, ash, and moisture
Bl di i l– Blending is common place
• Improvement in coal quality may result in satisfying specs for new
t ti l tpotential customers.• If energy exceeds spec, coals may
be used as blends.Bl d ith l lit I d i– Blend with lower quality Indonesian or domestic coal
• Decrease in ash will assist plants with expensive ash disposal costswith expensive ash disposal costs.
• Producer can now trade in new identified markets.
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Power Plant Locations
100+ Mt Import40‐100 Mt Import10‐40 Mt Import1‐10 Mt Import0‐1 Mt Import0 Mt Import0‐1 Mt Exportp1‐10 Mt Export10‐40 Mt Export40‐100 Mt Export100+ Mt Export
Power Plant
Value‐in‐Use of Thermal Coal• Typical Indian power plant simulated• Typical Indian power plant simulated• General trend of decreasing
Generation costs as coal energy increases.increases.
• Other coal quality parameters can have a significant effect on generation costs (Hence observed scatter)
• Shows a decrease of $0.25/MWh in Generation costs. Equates to $1 4million pa for 800MW plant$1.4million pa for 800MW plant.
• Higher coal price can be negotiated as power plant will achieve lower generation costs.generation costs.
• Higher value coals can ‘travel’ further and expand market share potential.