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A model of solid-liquid separation of mining slurries: experimental validation and scale-up
- M. Larenas & P. Garrido
A model of solid-liquid separation of mining slurries: experimental - - PowerPoint PPT Presentation
A model of solid-liquid separation of mining slurries: experimental - - PowerPoint PPT Presentation
A model of solid-liquid separation of mining slurries: experimental validation and scale-up M. Larenas & P. Garrido Centro de Investigacin JRI mlarenas@jri.cl, pgarrido@jri.cl www.ci-jri.cl Contents Context The model Experimental
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Tailings thickener, Minera Los Pelambres
Main goals: Water recovery (dewatering) Increase solids concentration Thickened tailings for final disposal Complex process in theoretical and operational aspects Need to understand phenomenology
Thickening in the mining industry
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Thickening in the mining industry
Operational difficulties:
Low discharge concentration
Bad quality supernatant (overflow)
High torque, embankment
Requirements of design conditions are not met
1% 3% 4% 7% 10% 26% 28% 17% 4% 0% 0%
60.000 70.000 80.000 90.000 100.000 110.000 120.000 130.000 140.000 150.000 160.000 170.000
0% 3% 5% 8% 10% 13% 15% 18% 20% 23% 26% 28% 31% Frecuencia
Copper tailings thickener Frequency diagram
Operational data 2012-2014 Source: JRI Average=117.5 Ktpd Nominal=142.5 Ktdp
< 4%
Frequency
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Contents
Context The model Experimental validation Scale-up Conclusions
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The mathematical model
Bürger et al., “A model of continuous sedimentation of flocculated suspensions in clarifier-thickener units', SIAM J. Appl. Math. 65 (2005), 882-940.
fluxes consolidation
𝑣
1 sedimentation advection compression
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The mathematical model
Thickener Simulator
Geometry
𝑦
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The mathematical model
Batch test:
5 10 15 20 25 30 35 5 10 15 20 25 Interface height [cm] Time [min]
Interface height vs time (9% w/w)
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The mathematical model
Settling velocity
5 10 15 20 25 30 35
0.05 0.1 0.15 0.2 0.25 0.3 0.35
Settling velocity [cm/min] Concentration w/w
500 1000 1500 2000 2500 3000 3500 4000
0.1 0.2 0.3 0.4 0.5 0.6 0.7 Effective solid stress [Pa]
Concentration w/w
Effective solid stress
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Contents
Context The model Experimental validation Scale-up Conclusions
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Experimental validation: batch operation
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Experimental validation: batch operation
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Experimental validation: continuous operation
0.4 0.42 0.44 0.46 0.48 0.5 0.52 0.54
50 100 150 200 250
Discharge concentration Time [min]
10 20 30 40 50 60 70 80 90 100
50 100 150 200 250 Height [cm] Time [min] Column height 1 [m] UA 0,1 [m2/tpd] Feed 12 [%w/w] Discharge (design) 52 [%w/w] Flocculant dose 15 [gpt]
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Experimental validation: continuous operation
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Contents
Context The model Experimental validation Scale-up Conclusions
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Scaling-up
Feed
Total production 22,000 [tpd] Feed concentration 31 [%w/w] Dilution concentration 6 [%w/w] Solid density 2.69 [gr/cm3] Flocculant dose 15 [gpt]
Discharge
Unitary area (design) 0.0890 [m2/tpd] Discharge concentration (design) 56 [%w/w] Yield stress <50 [Pa]
Torque
Torque K-factor 54 [ft·lb/ft2] Safety factor Factor K 5.35 [-] Torque 1,440,000 [ft·lb]
Dimensions
Diameter 50 [m] Total height 10 [m] Base slope 14 [°]
50 m 10 m
14°
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Scaling-up
4,1 m Solids
Production 22,000 [tpd] Feed concentration 31 [%w/w] Discharge concentration 56 [%w/w]
Water
Feed flow 0,567 [m3/s] Supernatant flow 0,340 [m3/s] Recovery rate 60 [%]
Steady state (after ~8 h):
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Scaling-up
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Contents
Context The model Experimental validation Scale-up Conclusions
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Integrated approach
1: Laboratory
Characterization of representative samples according to mining plan
2: Semi-pilot testing
Settling column (1-4 m) to evaluate performance at reduced scale
3: Modeling
Design validation and identify operational improvements
4: Implementation
Carry out on-site actions following recommentations
Exhaustive analysis of thickener perfomance
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Conclusions
- 1. The proposed numerical simulator facilitates the assessment of
different thickener dimensions and operational scenarios.
- 2. The mathematical model is flexible and can be applied to
general solid-liquid suspensions (ore concentrate, mine tailings, wastewater).
- 3. Extended theoretical studies, experimental considerations and
the addition of other relevant phenomena, will contribute towards the consolidation of the mathematical model.
- 4. Laboratory tests (characterization of slurries), pilot-testing and
numerical simulations can be put together into an integrated system for the design and optimization of thickener operation at industrial scale.
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