Knight Piesold Elko Roundtable 2014 Drain Down from Waste Rock and - - PowerPoint PPT Presentation

▶
knight piesold elko roundtable 2014 drain down from waste
SMART_READER_LITE
LIVE PREVIEW

Knight Piesold Elko Roundtable 2014 Drain Down from Waste Rock and - - PowerPoint PPT Presentation

Feb 29, 2024 383 likes •896 views

Knight Piesold Elko Roundtable 2014 Drain Down from Waste Rock and Heap Leach Piles Thom Seal, PhD, PE Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E. Outline Introduction - Heaps & Dumps ROM Physical

slide-1
SLIDE 1

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Knight Piesold Elko Roundtable 2014 Drain Down from Waste Rock and Heap Leach Piles

Thom Seal, PhD, PE

slide-2
SLIDE 2

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

  • Introduction - Heaps & Dumps
  • ROM Physical Properties
  • Capillary Physics
  • Drain Down
  • Air Flow in Piles
  • How do we solve the drain down issue?

Outline

slide-3
SLIDE 3

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

  • Blasted Material is Run of Mine (ROM)

ROM

slide-4
SLIDE 4

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

ROM

slide-5
SLIDE 5

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Bulk Density

A. Equations: ώ = Voidage in Percent

  • Bulk Density = Mass + Voids

= D(1- ώ ) Volume

  • Bulk SG = Mass + Voids

= SG(1- ώ ) Volume

  • ώ = Volume of Voids/Total Volume
  • ώ =

Volume of Voids (Void Volume + Solid Volume)

  • ώ = 1 - Bulk Density/Density of Solids
  • ώ = 1 – BSG/SG
slide-6
SLIDE 6

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Voidage

slide-7
SLIDE 7

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Voidage

slide-8
SLIDE 8

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Heap & Dumps

  • Voidage: 2 to 40% voids in a ROM Heap
  • Voidage in -6” crushed material stacked

Ore Properties: Knight Piesold % Moisture 11% 131.10 #/ft3 Feet Normal Stress-Wet Wet Density dry Density Voidage Permeability: Down psf psi #/ft3 g/cm3 ft3/ton #/ft3 % K=cm/sec 2 144 1 82.9 1.33 24.1 82.49 25.48% 0.011 1.10E-02 49 5,500 38.2 111.9 1.79 17.9 99.59 24.03% 0.007 7.00E-03 94 11,000 76.4 116.9 1.87 17.1 104.04 20.64% 0.0034 3.40E-03 181 22,000 152.8 121.4 1.94 16.5 108.05 17.58% 0.00078 7.80E-04 247 33,000 229.2 133.7 2.14 15.0 118.99 9.23% 0.00024 2.40E-04 300 39,059 271.2 143.6 2.30 13.9 127.85 2.48% 0.000111 1.11E-04

slide-9
SLIDE 9

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Heap & Dumps

Constant Head Permeability Test Data 50 100 150 200 250 300 350 0% 5% 10% 15% 20% 25% 30%

Percent Voidage Heap Height (ft)

slide-10
SLIDE 10

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Heap & Dumps

Dry Weight vs. Heap Height Data

y = 0.1303x + 87.869 R2 = 0.9287 20 40 60 80 100 120 140 50 100 150 200 250 300 350 Heap Height, ft. Dry Density pcf

slide-11
SLIDE 11

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Solution Retention and Capillarity

slide-12
SLIDE 12

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Solution Retention and Capillarity

slide-13
SLIDE 13

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Solution Retention and Capillarity

slide-14
SLIDE 14

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Drain Down Physics

slide-15
SLIDE 15

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Solution Retention and Capillarity

Soil Moisture Blocks - Readings vs. % Moisture 20 40 60 80 100 120 1000 2000 3000 Time in min. Meter Reding

5 % Moisture 10 % Moisture 15 % Moisture 20 % Moisture

slide-16
SLIDE 16

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Drain Down Physics

  • 3 forces, gravity, surface tension and

atmospheric pressure

  • Surface tension is the molecular attraction that

causes water to preferentially adhere to solid surfaces over air and thereby displace air from both internal microporosity and void space.

  • Hydroscopic water is the water that clings to the

particles in the heap.

  • Solution will drain until gravity = surface tension
  • As particle size decreases the capillary rise will

increase

slide-17
SLIDE 17

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Drain Down Physics

  • Clays (ultra fine particles with a lot of void

space) tend to be saturated with water unless evaporated

  • Solution fills all void space for rock sizes less

than 48 mesh (0.3 mm) and will exclude air

  • Rocks coarser than 10-20 mesh (1 mm)

drainage will be almost complete and most of the void space will be filled with air

  • Solution is retained in minus 40 mesh rock

without exterior heating force

slide-18
SLIDE 18

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Drain Down Physics

slide-19
SLIDE 19

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Heap Drain Down Data

NON-Property - Phase I Pad - Rinse

100 200 300 400 500 600

6/8/01 7/28/01 9/16/01 11/5/01 12/25/01 2/13/02 4/4/02 5/24/02

Date Flow - Preg (gpm) Cell 1-1 Cell 2-1 Cell 1-2

20 Days Drain

slide-20
SLIDE 20

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Heap Drain Down Moisture

Average 6.75% Moisture

% Moisture HJ-4; NP Drill Samples, 5 ft Intervals

5 10 15 20 25 30 35 10 20 30 40 50 60 70 80 90

Depth in Heap (ft) % Moisture

slide-21
SLIDE 21

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Pan Evaporation – Elko NV

slide-22
SLIDE 22

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Drain Down Chemistry

slide-23
SLIDE 23

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Drain Down Chemistry

slide-24
SLIDE 24

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

US Drinking Water Standards

slide-25
SLIDE 25

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

US Drinking Water Standards

List of EPA National Secondary Drinking Water Regulations Contaminant Secondary Standard Aluminum 0.05 to 0.2 mg/L Chloride 250 mg/L Color 15 (color units) Copper 1.0 mg/L Corrosivity noncorrosive Fluoride 2.0 mg/L Foaming Agents 0.5 mg/L Iron 0.3 mg/L Manganese 0.05 mg/L Odor 3 threshold odor number pH 6.5-8.5 Silver 0.10 mg/L Sulfate 250 mg/L Total Dissolved Solids 500 mg/L Zinc 5 mg/L

slide-26
SLIDE 26

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Penetration into Piles

  • B. Gaseous Diffusion of Oxygen in Ore Heaps
slide-27
SLIDE 27

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Penetration into Piles

  • B. Gaseous Diffusion of Oxygen in Ore Heaps
slide-28
SLIDE 28

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow Example: Biooxidation

  • B. Gaseous Diffusion of Air in Ore Heaps
slide-29
SLIDE 29

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow Examples: Biooxidation

  • F. Bioheap Energy Balance and Temperature Control
slide-30
SLIDE 30

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow Example: Biooxidation

  • B. Gaseous Diffusion of Oxygen in Ore Heaps
slide-31
SLIDE 31

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow Example: Biooxidation

  • G. Forced A ir Ventilation of Ore Heaps
slide-32
SLIDE 32

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • C. Vertical Air Flow by Natural Air Advection
  • Air velocity through a heap is limited by ore

permeability and pressure gradient simplified by Darcy’s Equation

  • Small pressure gradient, so air flow is laminar
  • Flow due to change in buoyancy due to the

decrease in density (PV = nRT)

slide-33
SLIDE 33

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Properties

slide-34
SLIDE 34

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • C. Vertical Air Flow by Natural Air Advection
  • Air velocity is a function of the change in air

density

  • Air becomes saturated with water vapor from

the contact with the wet heap

  • Air heated from the thermal mass of

exothermic sulfide oxidation or change in temperature

  • Air loses oxygen due to chemical and

biological processes

slide-35
SLIDE 35

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • C. Vertical Air Flow by Natural Air Advection
  • Air velocity depends on the change in air density
  • Average pressure gradient in the heap:
slide-36
SLIDE 36

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

Vertical Air Flow by Natural Air Advection

  • Diffusion kinetics controlled by
  • Water vapor saturation
  • Solution in void space
  • Channeling parallel to dump angle of repose 37o
  • Compaction and impermeable zones
  • Salts and evaporates fill in voids and micropores
  • Ponding on the surface & perched water table
  • Heating from exothermic reactions & Loss of

dissolved oxygen by chemical/biological reactions if present.

slide-37
SLIDE 37

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • D. Air Flow by Natural Advection from the Sloping Sides of Ore Heaps
  • Air flow into toe of heap and channels

upward

  • Segregation of dumped ore
  • Few fines
  • Modeling air flow
  • Bottom of heap has higher permeability

due to segregation of boulders and few fines allows air to travel farther under the dump prior to turning up

slide-38
SLIDE 38

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • C. Vertical Air Flow by Natural Air Advection
slide-39
SLIDE 39

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Permeability

slide-40
SLIDE 40

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • D. Air Flow by Natural Advection from the Sloping Sides of Ore Heaps
  • Good permeability required (100,000 Darcy) at

45oC for 1 year biooxidation (found in wet coarse gravel) and several years for permeability of 10,000 Darcy

  • Normal heaps 10 to1,000 Darcy
  • Permeability is the media (void spaces) not the

solution

  • Clay and fines reduce permeability even more

and reduce air flow

slide-41
SLIDE 41

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Air Flow in Piles

  • C. Vertical Air Flow by Natural Air Advection
slide-42
SLIDE 42

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Soil Covers

slide-43
SLIDE 43

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Sponge Theory

slide-44
SLIDE 44

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

  • In areas of Negative Pan Evaporation
  • Allow the sponge (pile) to dry out in the

summer

  • Allow the sponge (pile) to absorb the

meteoric water during events Hypothesis:

  • If the pile can be dried out during the

summer then the pile will absorb the meteoric water with no discharge.

Sponge Theory

slide-45
SLIDE 45

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

Meteoric Water Flow

  • Fill capillaries – no flow
  • Percolation – flow less than local hydraulic

conductivity

  • Solution Flooding flow more than local hydraulic

conductivity

  • Flooding always proceeds upward from a

bottleneck

  • Local flooding channels excess solution

laterally to find a path of high hydraulic conductivity

slide-46
SLIDE 46

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

  • Inject over 200,000+ gal/zone (7,500 m3)
  • f solution, plus.
  • Improve the permeability to 100 ft+ radius.
  • Long after injection, the uncovered well

has observed high humidity and a wet well casing.

Hydro-Jex Operational Data

slide-47
SLIDE 47

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

HJ Pattern.

Hydro-Jex Operational Data

slide-48
SLIDE 48

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

  • InJection and Exhaust
  • US Patent underway
  • Designed to dry out piles
  • Uses Green Technology
  • Disclose May 19, 2014 @

Innovations of Heap Leach, Tails and Waste Rock Management, UNR

Dry-Jex

slide-49
SLIDE 49

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

References

  • D.G. Fredlund, & H. Rajardjo, Soil Mechanics for

Unsaturated Soils, J Wiley, 1993

  • R.W. Bartlett, Solution Mining, Leaching and Fluid

Recovery of Material - 2nd Edition, by 1998, ISBN 90-5699-633-9, Gordon and Breach Publishers

  • G.H, Geiger, & D.R. Poirier, Transport Phenomena in

Metallurgy, 1973

  • http://water.epa.gov/drink/contaminants/#Inorganic
slide-50
SLIDE 50

Elko Roundtable-14 Drain Down from Mine Piles Thom Seal, Ph.D., P.E.

  • Dr. Thom Seal, PE Mining-Mineral Process

Mackay Mine 303 tseal@unr.edu 775-682-8813

Contact Information