s9!14!20 christian goni
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CONTROL AND INVENTORY OF WATER PONDS IN TAILINGS EMBANKMENTS THROUGH
PHENOMENOLOGICAL MODELLING
Dr. Christian Goñi
Universidad de Concepción
ABSTRACTABSTRACT
The conventional technology of mineral processing plants, consider the recovery ofwater from tailings dams, through the formation of ponds and groundwaterinfiltration or seepage.
The formation of ponds involved several complex phenomena such as evaporation, seepage, sedimentation, compression, pipeline, dam topology, etc. To quantify theavailable water in time, has set a goal to develop a dynamic model of the inventoryof water in the lagoon. To do this, we used phenomenological modeling techniquesand the development of numerical schemes using the finite volume resolution.
The result was a dynamic simulator software of the lagoon, whose estimated areaand volume of ponds are successfully validated by information collected fromplants.
We conclude that the simulator can estimate the water availability for a given time horizon, from initial conditions of the pond, tailings, water recycling and physicalcondition of the dam
Dr. Christian Goñi , cgoni@udec.cl
The problem of water recycling by treating The problem of water recycling by treating tailingstailings
The deposition of tailings into a dam allows the sedimentation of these generating a flow of water which then drains into the lower zones of the dam forming parasitic ponds. The water accumulated in these ponds is then transported to the mining operations, to achieve recovery of this.
The formation process of the pond is complex, involving several dynamic phenomena such as water transport, sedimentation, evaporation, infiltration and compaction of the tailings. Because of this, knowledge of the inventory of water over time is a mystery to solve for the efficient management of water recovery.
The aim of this study was to construct a physical model that accounts for the variation of water in the formation of pond. Thus, it is possible to predict water availability in the time, given the initial conditions of the dam and tailings deposition horizon.
Dr. Christian Goñi , cgoni@udec.cl
Some examples of ponds in tailings dams
Dr. Christian Goñi , cgoni@udec.cl
Example artificial pond for water recovery
Artificial pond
Dr. Christian Goñi , cgoni@udec.cl
Lagoon
Tails
Dr. Christian Goñi , cgoni@udec.cl
Tails
Channeling
Pond
Dr. Christian Goñi , cgoni@udec.cl
Deposition of tails
Basic elements of a tailings pond
water drains through the surface of the tailings into the lower areas, to accumulate in the form of ponds
Dr. Christian Goñi , cgoni@udec.cl
Lagoon
Slope(gravitational water drainage)
Channelingphenomena
Artificial pondFor waterrecovery
Lagoon (pond) formation
Dr. Christian Goñi , cgoni@udec.cl
MODELINGMODELING THETHE PHENOMENOLOGYPHENOMENOLOGY
Physical Phenomena• The physical phenomena considered in the formation of the pond (or
lagoon) are as follows :
– Tails and water transport (Convective and Diffusive Flux)
– Sedimentation tails (Hindered sedimentation model)
– Channeling (Empirical model for assays in laboratory)
– Runoff surface (Model and assays)
– Evaporation pond (Model and assays)
– Compression soil (Model and soil‐test)
– Seepage ( Conservation laws for water)
– Pond formation (Conservation laws)
Dr. Christian Goñi , cgoni@udec.cl
Conceptual model of the dynamics of water flowTransport tails andwater channeling
TASK
Dr. Christian Goñi , cgoni@udec.cl
Parameters and variables in process
Dr. Christian Goñi , cgoni@udec.cl
Evaporation rate modelling
Dry
Wet
Channeled
Water pond
according to the type of surface evaporation has different formulation in terms of linear speed and exposed area
flow corresponds to greater evaporation
( ) ( )eQ A t e t= ⋅
0 00, ,soile
KQ if t t Q Qt∞
⎛ ⎞= > ≠ +⎜ ⎟⎝ ⎠
Dr. Christian Goñi , cgoni@udec.cl
Typical rate evaporation in ponds
Dr. Christian Goñi , cgoni@udec.cl
InfiltrationVertical unsaturated flow of moisture in soil can be described physically by the equationpartial derivatives of Richards (1931), combination of unsaturated flow equation of Darcy-Buckingham and the continuity or mass conservation
1HKt z zθ∂ ∂ ∂⎛ ⎞= +⎜ ⎟∂ ∂ ∂⎝ ⎠
Richards equation:
( )infv k h H= − ∇Darcy - Buckingham:
However, developing a pattern of granular material to simulate the flow of infiltration in a tailings. The results were better.
Dr. Christian Goñi , cgoni@udec.cl
Green – Ampt Model infiltration in soils
Dr. Christian Goñi , cgoni@udec.cl
Infiltration modelingModeling of water infiltration through the porous soil under the pond, was performed by applying discrete particles for tailings under pond . It is considered a given thickness of infiltration
This allowed us to construct a proper boundary condition for the flow of infiltration in the lagoon
Soil sample like granular set
Dr. Christian Goñi , cgoni@udec.cl
Modeling of the tails sedimentation
( )
( ) ( )
2
18
1
sed
n
v v f
d gv
f
φ
ρμ
φ αφ
∞
∞
=
Δ=
= −
The tailings particles sediment under a regime hindered and laminar flow conditions. Reynolds considered around 10 - 1000.
important is the viscosity of the mixture water - tailings ( ), , . .f d C Qμ φ=
Dr. Christian Goñi , cgoni@udec.cl
Modelling “Channeling”
Channeling is the phenomenon of surface water runoff sediment through the tailings
( ), , ,...channelv f roughness thickness inclinated=
{ }, ,μ ρ τ•Viscosity•Density•Surface tension•Roughness•Thickness•Inclinated level soil•Perimeter pond
Dr. Christian Goñi , cgoni@udec.cl
Modeling of the topography of the dam
A topographic mapping from a tailings dam, it generated a three-dimensional geometric model. Then, depending on the altitude of tailings filling identifies the lower area where the lake was formed.
dam pondΩ = Ω ΩU
Dr. Christian Goñi , cgoni@udec.cl
Contour diagram of the tailings dam
Boundary embankment
Interior levels contour
Dr. Christian Goñi , cgoni@udec.cl
Example contour for tailings damDatabase (x,y,z)
Pos-processing in MATLAB
Dr. Christian Goñi , cgoni@udec.cl
ExampleExample ofof pondpond
Dr. Christian Goñi , cgoni@udec.cl
ManuallyManually constructionconstructionofof perimeterperimeter pondpond
SIMULATIONSSIMULATIONS
point of pumping and water recycling
CASE I. Tails with high fines
Dr. Christian Goñi , cgoni@udec.cl
DepositionsDepositions tailstails pointspoints((settingsetting forfor useruser))
pondpond
Some physical parameters
Dr. Christian Goñi , cgoni@udec.cl
values given by the user
Tab for water recovery flow (given for the user)
Physical properties of soil and water
Parameters of simulation
Dr. Christian Goñi , cgoni@udec.cl
ResultsResults ofof simulationsimulation
Dr. Christian Goñi , cgoni@udec.cl
Case I: Case I: ResultsResults forfor pondpond estimationsestimations
Dr. Christian Goñi , cgoni@udec.cl
Case I: Case I: ResultsResults forfor flowsflows involvedinvolved
Dr. Christian Goñi , cgoni@udec.cl
Case I: Case I: FlowsFlows ((feedersfeeders) ) inputinput forfor thethe useruser
Dr. Christian Goñi , cgoni@udec.cl
Case Case IIII: : ResultsResults forfor pondpond estimationsestimations
Dr. Christian Goñi , cgoni@udec.cl
Case Case IIII: : ResultsResults forfor flowsflows involvedinvolved
Dr. Christian Goñi , cgoni@udec.cl
Case Case IIII: : FlowsFlows ((feedersfeeders) ) inputinput forfor thethe useruser
A tool for simulation and calculation has been obtained from the dynamic modeling of water flow between the lagoon and the tailings dam. It’s possible include information of plant such as measurable fed tailings flows, percentage of solids, water pumping rates and deposition program.
The simulator is able to determine the dynamic evolution of the volume of the lagoon as well as the maximum depth and surface area of this
You can program the tailings deposit according to water availability estimates obtained with the simulator developed
The simulator can maintain control of tailings deposition scheduling with plant information
The simulator can simuling diffrents soil types (high fines, clays, etc.)
CONCLUSIONSCONCLUSIONS
Dr. Christian Goñi , cgoni@udec.cl
FINFIN
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