SUMMARY NOTES MEND WORKSHOP

“Managing Mine Wastes in Permafrost Zones”

University of Alberta Edmonton, Alberta

May 5,1997

This workshop was presented and sponsored by Falconbridge Limited University of Alberta

and MEND Secretariat

May 8,1997

May 8,1997

Participant;

The MEND Prediction and Monitoring Committee would like to take this opportunity to express our appreciation for your participation in the recent MEND workshop held in Edmonton May 5, 1997. The workshop, “Managing Mine Wastes in Permafiost Zones “, was a success primarily due to the high degree of interest and involvement by the participants. The comments on specific gaps in technology Will be used by the MEND Secretariat to assist for formulating the requirements for post-MEND research in northern climates.

We also appreciate your suggestions for additional topics, and for ways of making these technology transfer sessions more effective.

A summary of the pane1 discussion is provided in Section 2. Copies of the presentations and in some cases additional technical materials are included in Section 2.

If you have any questions or require iûrther information, please do not hesitate to contact me.

Sincerely,

CL-PJ@

Carl Weatherell Coordinator, MEND Prediction and Monitoring TEL: (613) 995-3097 FAX: (6 13) 947-5284 E-mail: weathere@nrcan.gc.ca www: http://www.nrcan.gc.ca/mets/mend

TABLE OF CONTENTS

1. WORKSHOP ATTENDEES 2. SUMMARY OF OPEN DISCUSSION 3. PRESENTATION OVERHEADS

3.1. INTRODUCTION TO WORKSHOP 3.2. OVERVIEW OF MEND 3.3. SUMMARY OF MEND STUDY - STATE-OF-THE-ART 3.4. ECHO BAY - LUPIN MINE 3.5. FREEZE BACK OF RECLAIMED TAILINGS AT NORTH RANKIN NICKEL MINE 3.6. LEACHING CHARACTERISTICS OF CULLATON LAKE TAILINGS 3.7. SUMMARY OF CURRENT RESEARCH WORK ON TAILINGS 3.8. PERMAFROST: IMPLICATIONS FOR MINESITE-DRAINAGE CHEMISTRY 3.9. A MODEL FOR PERMAFROST FORMATION IN WASTE ROCK PILES AT THE BHP DIAMONDS PROJECT 3.10. RESEARCH PRIORITIES FOR NORTHERN ARD 3.11. SUMMARY OF GAPS IN CURRENT KNOWLEDGE

1. WORKSHOP ATTENDEES

Martin Barnett DIAND 10 Wellington Street, 6th Floor North Tower, Room 604 Ottawa, Ontario KlA OH4 (819) 997-0912

Thorben Bieger Environment Canada Environmental Protection Board Box 370 Yellowknife, NT X 1 A 2N3 (403) 920-6059 (403) 8738185

David Blowes University of Waterloo Waterloo Centre for Groundwater Research Waterloo, Ontario N2L 3Gl (5 19) 8884878

Wayne Cors0 BHP Diamond 550 California Street San Francisco, CA 94 104 (415 )774-25 19 (415) 774-2034

Richard Dawson Norwest Mine Services Ltd. 400,205 9 Avenue SE Calgary, AB T2G OR3 (403) 237-7763 (403) 263-4086

Catherine Baskin Aurora Research Institute P.O. Box 1450 Inuviq, NT XOA OTO (403) 979-3298 (403) 979-4264

Kevin Biggar University of Alberta 220 Civil/Electrical Engineering Building Edmonton, AB T6G 2G7 (403) 492-2534 (403) 492-8 198

Jim Cassie Golder Associates 1011 Sixth Avenue S.W. Calgary, AI3 T2P OWl (403) 299-4635 (403) 299-5606

Nand Davè NRCan Elliot Lake Laboratories P.O. Box 100,99 Spine Road Elliot Lake, Ontario P5A 2J6 (705) 461-7015 (705) 848-9788

Steve Day Norecol, Dames and Moore 650 West Georgia St., Suite 1900 Vancouver BC V6B 4N7 (604) 681-1672 (604) 687-3446

Gerry Demchuk Manalta Coal Ltd. P.O. Box 2880 Calgary, AB T2P 2M7 (403) 23 1-7176 (403) 269-8075

C%ris Doupe PWGSCI Env. Services 1000,970O Jasper Avenue Edmonton, AB T5J 4E2 (403) 497-3889 (403) 497-3 842

Larry Dyke NRCan, GSC 401 Lebreton Street Ottawa, Ontario KlA OE8 (613) 996-1967

Maria Falutsu Cominco Alaska Inc. Red Dog Mine, P.O. Box 1230 Kotzebue, Alaska 99752 (907) 426-93 15 (907) 426-2 117

Tim Grain-Joseph James Progithin International 8403-l 87 Street Edmonton, AB T5T lH9 (403) 48 l-4452 SAME

Tom Dereniwski Syncrude Canada Ltd. P.O. Bag 4009, M.D. X302 Fort McMurray, AB T9H 3Ll (403) 790-7986 (403) 790-7550

Lisa Dyer Dept. of Resources Wildlife and Economie Development Government of NT 600,5 102 - 50 Avenue Yellowknife, NT XlA 3S8 (403) 873-7654 (403) 873-022 1

Sean Ennis Box 6387 Edson, AB T7E 1T8

Grant Feasby MEND Secretariat 555 Booth Street, Room 328 Ottawa, Ontario KlA OGl (613) 992-8736 (613) 947-5284

C%ris Grapel EBA Engineering Consultants 14535,118 Avenue Edmonton, Al3 T5L 2M7 (403) 451-2121 (403) 454-5688

Ed Grozic Umversity of Alberta #1202,11135-83 Avenue Edmonton, AB T6G 2C6

Holger Hartmaier Acres International Limited 500,102Ol Southport Rd. SW Wiwx 43 (403) 253-9161 (403) 255-2444

Elisabeth Hivon EBA Engineering Consultants 14535,118 Avenue Edmonton, AB T5L 2M7 (403) 451-2121 (403) 454-5688

Bill Horne EBA Engineering Consultants 14535 118 Avenue Edmonton, AB T5L 2M7 (403) 451-2121 (403) 454-5688

Pat Landine Senior Hydrogeologist Cameco 2121, 1 lth Street West Saskatoon, SK S7M lG3 (306) 956-6413 (306) 956-6201

Bill Gunter Alberta Research Council P.O. Box 8330 Edmonton, AB T6H 5X2 (403) 450-5467 (403) 450-5083

Don Hayley EBA Engineering Consultants 14535,118 Avenue Edmonton, AB T5L 2M7 (403) 451-2121 (403) 454-5688

Dave Hohnstein 18831-81 A Avenue Edmonton, AB T5T 5B4 (403) 487-1795

Ken Kuchling Diavik Diamond Mines Suite 2300,639-5th Avenue SW Calgary, AB T2P OM9 (403) 261-6122 (403) 294-9001

Dennis Lawson Environment Canada Rm 300 - Park Plaza 2355 Albert Street Regina, SK S4S 4Kl (306) 780-6462 (306) 780-6466

Gord McKenna Syncrude Canada Limited 9421-17 Avenue Edmonton, AB T6N lH4 (403) 970-6909 (403) 970-6805

John Meyer Klohn-Crippen Consultants 114,6815 8th Street NE Calgary, Al3 T2E 7H7 (403) 274-3424 (403) 274-5349

Chris Mills 1096 Nanaimo Street Vancouver, BC V5L 4T2 (604) 255-4320 (604) 255-4220

Michael Nahir Public Works Canada 1000,970O Jasper Avenue Edmonton, AB T5J 4E2 (403) 43 l-1950 (403) 497-3 842

Rodney Olauson SRK Suite 800,580 Horby Street Vancouver BC (604) 681-4196 (604) 687-5532

Peri Mehling Mehling Environment 3 826 Balaclava Street Vancouver, BC V6L 2S8 (604) 731-4150

Sharon Meyer Homestake Canada Inc. P.O. Box 1115 Suite 1100, 1055 West Georgia St. Vancouver, BC V6E 3P3 (604) 684-2345 (604) 684-983 1

Kevin Morin Morwij k Enterprises Ltd #2401,289 Drake Street Vancouver, BC V6B 525 (604) 899-2244 (604) 899-6224

Rick Nutbrown Echo Bay Mines 98 18 Edmonton International Ah-port Edmonton, AB T5 J 2T2 (403) 890-8794 (403) 890-88 14

Matthew Otwinsowski University of Calgary Dept. Physics & Astr. Calgary, AB T2N lN4 (403) 220-9576 (403) 282-798 1

Dogan Paktunc NRCan 555 Booth Room 209 Ottawa, Ontario KlA OGl (613) 947-7061

Howard Plewes Klohn-Crippen Consultants 10200 Shellbridge Way Richmond, BC V6X 2W7 (604) 273-03 11 (604) 279-4337

Don Scott Univers@ of Alberta Dept. of Civil Engineering Edmonton, AB T6G 2G7 (403) 492-2636 (403) 492-8 198

Jim Swendseid Cominco Alaska Red Dog Mine, P.O. Box 1230 Kotzebue, Alaska, 99752 (907) 426-2170 (907) 426-2177

Carl Weatherell MEND Secretariat 555 Booth Street, Room 328 Ottawa, Ontario KlA OGl (613) 995-3097 (613) 947-5284

Tony Pearse C-9 Wilkes Rd. Mayne Island, BC VON 2J0 (250) 539-3015 (250) 539-3025

William Schafer Schafer & Associates Inc. 865 Technology Blvd. Bozeman, MT 59715-6186 (406) 587-3478 (406) 587-033 1

Dave Sego University of Alberta Dept. of Civil Engineering 220 Civil/Electrical Engineering Building Edmonton, Al3 T6G 2G7 (403) 492-2059 (403) 492-8 198

Roy Wares Braemore Resources Inc. 1522 West 62 Avenue Vancouver, BC V6P 2E9 (604) 261-3413 (604) 26 l-9504

Henry Westermann PWGSC/ Env. Services 1000,970O Jasper Avenue Edmonton, AB T5J 4E2 (403) 497-3889 (403) 497-3 842

Peter Wheeler Klohn-Crippen Consultants 114,68 15 8th Street NE Calgary, AB T2E 7H7 (403) 274-3424 (403) 274-5349

Rick Young NRCan Elliot Lake Laboratory P.O. Box 100,99 Spine Road Elliot Lake, Ontario P5A 256 (705) 461-7013 (705) 46 l-7002

2. SUMMARY OF OPEN DISCUSSION

An open discussion on current practice and priorities for future research on the issue of permafrost to manage mine wastes was held at the end of the workshop. Grant Feasby initiated the discussion by summarizing the information presented during the day and indicating the areas where substantial uncertainty remains. These comments are detailed in section 3.11 and capture the essence of the discussion.

In sumrnary, although engineered structures incorporating permafrost have been used successfully for mine waste control, there is a lack of fundamental knowledge pertaining to the geochemical aspects of the behaviour of mine wastes in northern environments. A number of competing factors need to be studied to fùlly understand the fundamentals of mine waste oxidation at low temperatures. Technical issues yet to be resolved include:

1. Oxidation kinetics at low temperatures; 2. Unfrozen water in tailings; 3. Freezing point depression by process chemicals; 4. Thermal effects of oxidation at low temperatures; and 5. Effective covers in permafrost zones.

Future areas of research should focus on addressing the issues above.

3. PRESENTATION OVERHEADS

3.1. INTRODUCTION TO WORKSHOP

Carl Weatherell MEND Secretariat

MANAGEMENT OF MINE WASTES IN PERMAFROST

ZONES

A MEND Workshop

May 5,1997

Objectives

CI TO present and discuss currently available knowledge on managing mine wastes in permafrost zones;

n AMD focus o TO identify knowledge gaps that need to

be fïlled.

Program

o Introduction LI Operator Experience LI Research Results LI Discussion - Practice, Requirements,

Priorities

Coming Attractions

o Fourth International Conference on Acid Rock Drainage

“Application of Technology ” May 3 1 -June 6, 1997

0 Visit MEND on Internet www.nrcan.gc.ca/mets/mend

4

3.2. OVERVIEW OF MEND

Grant Feasby MEND Secretariat

Mine Environment Neutral Drainage (MEND)

o A 9-year cooperative research program, financed and managed by three partners

LI 1997 is 9th and final year n New initiative under discussion n Better prediction tools n Cold weather environments

MEND is composed of.. CI 20 companies, 5 provinces, Canada o $18 million, tripartite funding 0 Volunteers o Defïned program for technology

development

6

3

MEND Organization

Secretariat -- Management I

Funding 0 Initial commitment

n 1/3 Industry, 1/3 Canada, 1/3 (5) Provinces

o Annual plan and budget u Project-by-project basis buy-in Q TO date approximately $16 million spent

8

What was Needed

o Reduction in liability associated with acidic drainage

What was Needed

o More accurate prediction techniques Q Cheaper closure methods for tailings and

rock and mine sites q More site-specifïc options

w new mines without acid o Cheaper, widely applicable monitoring

tools

10

MEND Results

~1 No magie bullets o Prevention best strategy o Existing sites:

n reduce, treat, monitor a New mines

H underwater disposa1 H “walkaway” possible

Some of MEND successes

o Buy-in by stakeholders n commitment to technology only H mining industry shares results w full disclosure

0 Volunteer participation

Other MEND Successes

CI Govemments working with industry H decision-makrs ut the table

CI Exper&e widely available CI New mines opening without AMD CI Major reduction in liability

Unfinished Business and Challenges

o Better science for acid generating waste rock

n Predictive methods - acid/no acid, rate, onset

H Delay of onset of acid 0 Walkaway technology for old tailings areas 0 Control of AMD in mine openings CI Reduce the mountain of information

7

Post MEND

o Retain network and expand to include international expertise

P Monitoring & Reporting Results

o Non-acid Issues

MEND A Successful Canadian

Enterprise

16

3.3. SUMMARY OF MEND STUDY - STATE-OF- THE-ART

Richard Dawson Norwest Mine Services

AN OVERVIEW OF PERMAFROST

FOR ARD CONTROL

RICHARD DAWSON NORWEST- MINE SERVICES

r NORWEST

OUTLINE

-BACKGROUND

- ISSUES

- CONTROL STRATEGIES

- RESEARCH REQUIREMENTS

Figure 1.1 Canada’s Northern Perniafrost Regions

Figure 2.1 NWT and Yukon Minesites Exhibiting Acid Mine Drainage

Y- NORWEST

COLD TEMPERATURE ARD ISSUES

- FREEZE AND THAW RATES

- OXIDATION RATES

-UNFROZEN WATER

-FREEZING POINT DEPRESSION

ESTIMATED ACTIVE LAYER THJ[rCKMESSES

8 - lJNSAT&TED WAsTEkcK : ‘-UATURATED TAILJNGS -

-- . --..--- . . . . . . . _....__......__._____...........~.

. . . . . . j . . . . .._.....__....__.................. ___.........

l*ooO 1,500 2,~

THAW INDEX (degrees C- days)

2500

Figure 4.1: Seasonal Thawing Thickness for Mine Waste in Permatiost Regions

warer

High sahity

Porece-

Figure 3.5 Distribution of Unfrozen water in frozen soils. (a) Low salt concentration pore fluid in Gne - graimed soil. (b) Hig-h salt concentration pore fluid in fined - graked soil. (a and b ) foilowing Sheeran and Ymg (1975j. (c) High salt concentration pore fluid in CoBcse - gmined soil.

If ----_________-___________ -------..e--_I.

1.40 -7

1.20 Ai

1.00

1 0.80 Li

1

0.60 i i i !

0.40 -j

0.20

*

0.00

A c 0 E F

0 -2 -8 -10

FIGURE 3-4. Unfrozen Water Content vs.Temperature Ifrom Anderson and Morgenstern, 1973).

4 - 8 ;tm Fraction Man&ester Chena Calgary iFme

FIGURE 3-6 Fkozen Hydradic Gmductivity vs. Unfrozen Water Content (after Horiguichi and Miller, 19?331.

1.20

1 LEGEND 4 0 Nicholson (1984)

- RATAP Equatioo

0 0.80 E-

0.00 5.00 10.00 15.00 28.00 25.00

TEMPERATURE (CELSIUS)

Figure 3.2: Relative Rate of Chemical Oxidation versus Temperature (adapted from Senes, 1991)

1. FREEZE CONTROLLED*

- PERIMETER FREEZNG - TOTAL FREEZING

2. FREEZE-THA W DEWATERNG*

3. ENGINEERED COVERS

4. SUBAQUEOUS DISPOSAL

5. COLLECTION AND TREATMENT

6. SEGREGATION AND BLENDING

CONTROL STRATEGIES FOR TAILINGS

*UNIQUE TO CULD CUbt4TEs

Legend

@ Loam tore

@ Sand prlsm

@ Rock blanket

@ Rock prlsm

@ Freezlng column

@ Froten alluvial deposit

@ Bedrock

‘1.

I STARTERDYE unnl FROZEN OlEREMlARD

m THAWEDTAIUNGS

B.YEAR I-SUMMER

CYEAR2-WINER

D YE;-\Rî,SMtf%

Figure 4.4: Tailings Thin Layered Freezing Dtt&p Ccmx@

TAILINGS SAND FREEZING LAYER THICKNESSES

20 ; 1

~ : . -G IN&=22@J°C DAY.5

- - FlEEZIM INDEX=305o’C DAYS

Ê _ - - -~G~~=3tJ(J@‘CDAyS

;1v 15 - . . . . . . . . . . . . . . . . . . . i . . - - - - - FfU3BING INDIX=72W”C DAYS

iii PERMAFROST .

FREQING

10

a 5

2

z

oi..““..“‘..,“,l”,.‘,’

0 1 2 3 4 5

PLACEMENT LAYER THICKNESS (m)

Figure 4.3: Tailings Sand Freezing Layer Thicknesses

THICKMSS

3.5 n

LEGEND

SANDY GRAVEL COARSE VASTE RIXK

INSULATICN

Figure 4.2: Insulating Cover options for Totai Freezing in Contimous Pernwfiost Regions (after MEND 6.1, 1993)

THICKNESS

3.5 n

3.0 PI

2.5 n

2.0 m

1.5 PI

1.0 n

os n

0.0 n

. _.. -_ .- . . B __ 1 .:. ._ ._ :.. .:

TW?~~~SYPH~N

w LEGEND

WAFSE VASTE RIXX

VASTE ROCK INSULATION

Figure 4.5: Insulating Cover Options for Perimeter Freezing (afier MEND 6.1, 1993)

r NORWEST

CONTROL STRATEGIES FOR WASTE ROCK

1. FREEZE CONTROL *- layered freezing

2. CLIMATE CONTROL*- segregation and zoning

3. ENGINEERED COVER

4. COLLECTION AND TREATMENT

5. SEGREGATION AND BLENDING

*COLD WEATHERSTRATEGIES

r

i i i Îù Elkviewcoalcorp. 1111 n ( HBT-AGR4 1994 1 -7

Silt

-copper~ GldakoMiios(Minewaste) (LaukuGdtetaLl976> I-L

lO.tX 1.00

Grain Size (mm 1

L I IIIII I I

0.01

Figure 4.6: Typical Grain Size Distributions of VVasre Rock Materials

MINE WASTE ROCK MINE WASTE ROCK VOID RATIO VS SATURATION RELATIONSHIPS VOID RATIO VS SATURATION RELATIONSHIPS

100 100 I I I I I I

l l IN SITIJ MOKTURE CONTENTS IN SITIJ MOKTURE CONTENTS

go -.......................... TA..... - _...._______.....___________ go -.......................... TA..... - _...._______.....___________ m m FEID CAPACITY MOEl-URE CXNENTS FEID CAPACITY MOEl-URE CXNENTS

. .

0 0 0 0 0.2 0.2 0.4 0.4 0.6 0.6 0.8 0.8

VOID RATIO VOID RATIO

Figure 4.7: Saturation Relationships for Sandy Grave1 Mine Waste Rock MaterAs

SANDY GRAVEL WASTE ROCK FREEZING LAYER TEIICKNESSES

- - - FREEZING INDEX=2200 degree C days

- - - FREEZING INDEX=3900 degree C days

- FREEZZING iNDEX=7200 degrtx C days

2 3 4 5 6 7 8 9 10 PLACEMENT LAYER THICKNESS (m)

Figure 4.8: Sandy Grave1 Waste Rock Freezing Layer Thicknesses

A. HEAPED CONSTRUCTiON

NON-ACIDIC WA!STE ROCK

ACIDIC FROi!EN CORE

COARSE WA!TE

B- END-DUMPED CONSTRUCTION

FftoEN -TE0 ACNHC WA= ROCK

Figure 4.9: Freeze Controlled ARD Cmtid Stm@egies f;oa Waste -Rock

NON-ACIDIC WA!3-E ROCK UFT

ACIDIC WASTE ROCK LIFI-S

\

B. RE-SLOPED CONFIGURATION

NOTE RE-SLOPfNG OF FINI3 SANDY GRAVEL WASl-ESERVESTOREDUCEAiRFLOWTHf&lBAsEOfflE COARSE DRAINAGE LAYER BENEATH NON-ACJDK U’PER UIT LfMlTS INFfLTRAT0N Ml-0 ACIDIC WA9-E

NON-AClDIC WA!XE ROCK UFI-

ACIDIC WASTE

Figure 4.10: Climate Controlled ARD Strategy for Terraced m-w* Construction

NORWEST

RESEARCH AND DEMONSTRATION REQUIREMENTS

- FREEZING POINT DEPRESSION DUE TO PROCESS CHEMEICALS

- ECONOMIC INSULATING COVER DESIGNS

- WATER AND HEAT TRANSFER IN WASTE ROCK DUMPS

3.4. ECHO BAY - LUPIN MINE

Rick Nutbrown Echo Bay Mines Ltd.

Presentation at the MEND Workshop: Management of Mine Wastes in Permafrost

, Zones, May 5, 1997 at the University of Alberta. Page 1

Introduction

The Lupin Operation is an underground gold mine on the west shore ofContwoyto Lake, about 400 km northeast of Yellowknife and 80 km south of the Arctic Circle. The deposit was discovered in 1960 by the Canadian Nickel Company, a subsidiary of INCO Ltd. Between ‘61 and ‘64, Canadian Nickel conducted exploration at the site including geological mapping, geophysical surveying, trenching, stripping and charme1 sampling. The site was purchased by Echo Bay Mines frorn INCO in the late ~OS, and initiated an underground exploration program in 1979. The information gained from this program indicated enough ore reserves to provide six years of production at ami11 processing rate of 950 tons per day. In August of 1980 the decision was made to proceed with development and construction of the mine. Commercial production began in 1982.

The mineralogy of the ore at Lupin consists mainly of amphibole, quartz, garnet, pyrrhotite, arsenopyrite, minor pyrite and trace chalcopyrite. The gold is fine grained, generally less 100 microns in diameter and is associated mainly with pyrrhotite and arsenopyrite. Although not common, visible gold has been reported, usually in close proximity to quartz veining.

The ore at Lupin has been shown through various studies to be capable of generating acid upon oxidation. The waste rock produced in the mining process contains very little sulphur (about 0.5%) and is considered to have very little potential of acid production.

In regards to site facilities, other than the transportation requirement for materials and supplies necessary to sustain the workforce and industrial operation, theLupin site is completely self contained. The two main complexes on the site are the kitchen/residential/accommodation buildings and the industrial complex which includes the mil1 and various maintenance areas, theheadframe, powerhouse, and warehouse areas and office facilities. Associated with the two complexes mentioned are support areas consisting of shops and various yards, cold storage buildings, explosives magazines, tank farms, the sewage facilities, the landing strip and aircraft control office, the mil1 tailings line and the tailings containment area.

Presentation at the MEND Workshop: Management of Mine Wastes in Permafiost Zones, May 5, 1997 at the University of Alberta. Page 2

Mining

As 1 mentioned, Lupin is an underground mine. Presently, the bottom of the mine is at about 1300 metres. Equipment employed includes diesel scoop trams and haul trucks and electric/hydraulic drilling equipment. Production is accomplished through a process of drilling, blasting and mucking. Broken ore is hauled to ore passes where it is put through a rock breaker to reduce the amount of oversize material, and routed to the skips for transport to the surface for milling.

Milling

The ore brought from underground is stored in a600 ton coarse ore bin. From the coarse ore bin, the ore is fed through cane crushers to two1000 ton capacity fine ore bins. The fine ore is then fed into the grinding circuit, first through a rod mil1 thertwo bal1 mills in a parallel configuration. The discharge from the bal1 mills is classified using hydrocyclones. The underflow from the cyclones, +200 mesh or coarse material, is fed back to the bal1 mills, while the overflow T-om the cyclones, -200 mesh or fine material, is pumped to the pre-aeration circuit.

The -200 mesh material enters pre-aeration thickener for settling of the solid fraction. The overflow solution from this thickener is returned to a recycle water tank while the

underflow slurry is pumped to the first of three pre-aeration tanks. These pre-aeration tanks provide air to oxidize the sulphide minerals which would otherwise consume large amounts of cyanide later in the milling process as well as increasing the risk of the formation of acid rock drainage in the tailings containment area. The pre-aeration circuit operates under alkaline conditions and has a lead nitrate reagent added and is diluted with recycle water.

Slurry from the pre-aeration circuit is pumped to a series of six agitated and aerated tanks where the gold is leached with cyanide. The gold particles are dissolved by a reaction between the cyanide, oxygen and water. Lime is used to maintain the system pH at about 10. After approximately 30 hours of retention, the slurry is transferred to the cyanidation thickener for separation of the solid and liquid fractions. The liquid fraction is known as the pregnant or gold bearing solution and is routed to the pregnant solution tank. The underflow slurry, which also contains some gold is pumped to the

Presentation at the MEND Workshop: Management of Mine Wastes in Permafrost Zones, May 5, 1997 at the University of Alberta. Page 3

filtration circuit.

A two stage filtration system separates the dissolved gold fi-om the solids by washing with barren or non-gold bearing solution. Each of the two stages consists of four vacuum drum filters. The slurry is retained on the outside of the filter unit while the solution is drawn through, taking the dissolved gold with it. The filter cake from the filtration circuit is either repulpedand pumped out to the tailings containment area or transferred to the paste backfill system for placement underground.

The pregnant solution is processed through three pressureclarifïers to remove fine suspended solids. Oxygen is then removed in a de-aeration orCrowne tower prior to precipitation. Zinc dust is added to precipitate thegold which is collected in the precipitation presses. Once the press becomes loaded with precipitate, it is transferred to the refinery. The precipitate is smelted in the bullion furnace to producedore bullion and slag. The slag is returned to the mil1 to be reprocessed. The bullion contains approximately 85% gold and 12% silver, the remaining impurities being base metals.

Paste Backfill

The first method of mine waste management that 1 Will briefly talk about is paste backfill. As 1 mentioned earlier, the solids collected on the vacuum fîlters areeither repulped and pumped to the tailings containment area or used as backfill underground. In general, the paste formed is a high density mixture of water and the fine filter solids. Cernent is added to the mixture and it is pumped underground through a pipeline to inactive mine voids or to active stopes. In 1997, we expect to dispose of 5040% of the tailings solids produced through the paste backfill operation.

Tailings Containment Area

The use of the tailings containment area is the second method of mine waste management used at Lupin. Any tailings solids not disposed of underground and a11 excess waters from the milling process are handled at the tailings containment area. The slurry is pumped f?om the mil1 to the TCA through an insulated 8” steel pipeline. The TCA is about 6 km south of theminesite and covers 361 hectares within a750

Presentation at the MJ3JD Workshop: Management of Mine Wastes in Permafi-ost Zones, May 5, 1997 at the University of Alberta. Page 4

hectare lease. There are three main components to the TCA, the solids retention cells, Pond 1 and Pond 2.

The tailings slurry pumped from the mil1 is first dumped into one of the solids retention cells where separation of the liquid and solid fractions occurs. These pictures show the slurry being dumped into an almost full area of the TCA.

At times, the tailings lines are strung out into the cells to fil1 in low areas of the cells and to avoid creating tailings beaches that are too close to the surface of the interna1 dams that divide the TCA.

The water is collected in Pond 1 and stored for up to 11 months before it is transferred to Pond 2. Pond 2 also retains the water for up to 11 months before it is discharged to the environment. This long retention period allows natural degradation to reduce the contaminants in the water. Typically, the cyanide concentration is reduced by up to 90% by the time the water is collected in Pond 1. Metals such as Zinc, Nickel and Copper are reduced by 70 to 80% in the fïrst phase of the retention.

Arsenic, on the other hand, is only reduced by about 25%. For this reason, during the transferred from Pond 1 to Pond 2, an iron salt (ferric sulphate) is added to the water to form a stable iron/arsenic precipitate which settles in Pond 2. Lime is also added for pH adjustment.

The TCA is impounded through natural terrain relief and a series of engineered retaining structures. Due to the selection of natural lakes as polishing ponds and the low relief of the surrounding land, the perimeter dams generally vary up to about metres in height.

This schematic shows a general cross-section of the dams. The upstream side employs a synthetic liner covered with sand andriprap. The synthetic liner is for initial control of seepage while the frozen tore of the dam develops.

Various studies have been initiated over the life of the mine to evaluate the extent of the development of the frozen dam cores as well as the thickness of the active thaw zones in reclaimed sections of the tailings containment area. These reclaimed areas

Presentation at the MEND Workshop: Management of Mine Wastes in Permafrost Zones, May 5, 1997 at the University of Alberta. Page 5

are sedimentation cells that have been fïlled to capacity with tailings and covered with a layer of esker gravels. The intent of covering the tailings is to form a barrier to prevent the oxygen transfer responsible for the eventual formation of acid rock drainage. As well, the depth of esker caver Will be adjusted to place the long-ter-m active thaw zone above the tailings, thereby keeping the tailings in a permanently frozen condition, mrther reducing the risk of ARD production. The following series of overheads shows the results of some of the ground temperature work undertaken over the past couple of years.

1

l U.S.A.

Photo I AeriaJ view of Lupin minesite on 29 June 1993 Noce clxtenl 01 vx caver on waterbodies

Photo 2 Aerial view of Norma Lake (left) and Norma Pond (right) with tailings pond in the background. Photo on 29 June 1993.

Abandonment And Restoration Plan January, 1996

Figure 3; Lupin Mine Tailings Area - 1995

GRAPH OF TEMPERATURE VERSUS DEPTH FOR THERMISTOR TCl-1

- 28-OCI-95

+ 5-Nov-95

.+ 22-Nov-95

* Itacc-95

- X-Jan-%

+ 28-Jan-96

--+- I I-Fcb96

+ 2.LFcbY6

-- 2-Apr-96

-+ 27-Ap-Y6

-+- II-Mq-%

---j+ 27-MU+6

- IO-JUII-96

-+-- 24-Jun-%

-&-- X-July-%

-j(--- 22-JulyY6

__ &Aug-96

-+- IZ-Aug-96

-f- 29-AU~-%

* a-sep%

- 22-Scp96

+ s-ckl-%

-&-- IR-ocI-%

+ ~-NOV-%

I6-Nov-%

I-lkc-%

IJ-DIX-Y6

Temperature (OC)

3:Wrojccl Filcs\~l7.\9~\Grapl~cr\Lupill I- I .grC

- 4

-10

‘.

End of Hole 13. I metres

Klohn-Crippen

GRAPH OF TEMPERATURE VERSUS DEPTH FOR THERMISTOR TCl-2

- 28-chx-9s

+ S-Nov-95

-&r- U-Nov-95

* 16-Dec-9s

- Lt-Jan-96

-+- 2&Jan-%

-+- I I-F&%

-++ 24-Fcb-%

-_-__ 2-hpr-Y6

+ 21-Apr-%

- -&-- I I -May-Yh

-+-- 21-MayY6

- IO-Jun-Y(>

+ 24-Jun-%

-k- RJuIy%

-+- 22-JulyY6

- 6-chu&!-%

+ 12-Aug-%

-A- ZY-Aug-%

* Il-Scp96

- 22-Scp-%

+ 5-ckt-Yfl

* I x-oct-Y6

.-++ ~-NOV-%

I 6-Nov-Y6

I-Dec-%

IJ-Dec-Y6

Temperature (OC)

40

t-

End of Bole 13.1 metres

I:\Projec~ Files\M759Z\Graphcr\Lupin l-2g-f

Klohn-Crippen

GRAPH OF TEMPERATURE VERSIJS DEPTH FOR THERMISTOR TCl-4

T 2

Temperature (OC)

!- End of Holt 13.0 metres

-1-l

h;lohn-( ‘rippcn

Klohn-Crippen

GRAPH OF TEMPERATURE VERSUS DEPTH FOR THERMISTOR D4-1

Temperature (‘Y)

f

I I

’ -ProJcct Fllcs\h,l7i’~~‘~.Grapllcr\Lup~~~~- I grl

Klohn-Crippen

. . . . .

End of Hole 12.8 metres

Klohn-( ril)pcrl

GRAPH OF TEMPERATURE VERSUS DEPTH FOR THERMISTOR D4-2

Tem perata re (OC)

- 2%Ou-95

+ 5-Nov-95

-&- 22-Nov-Y5

+ 16-lkc-Y5

- LI-Jan-Y6

2%Jan-YO

--&- I I -I-&-Y6

* IJ-l;ct+x>

-.------ *-/Qr.‘K

+- 27-4-n-%

t Ii -kr-Ch>

Y ?l-Mm-ch>

--.- IO-Jun-Y6

+- WJun-‘M>

-++ 22.JIII> -v<>

--- - 6-hug-Y6

-+ 12-Au@6

-A-- ZY-hug-Ye

--+Y+ R-Sep-?Ht

- 22-Scp-Yh

+ 5-<kl-Yh

--&-- I Mkl-‘Xv

-++- ~-Nov-96

I6-No\ -Y6

I -Dec-Y6

IJ-lkc-Y6

- -6

E = c

c”

- .s

. ..- “” ---........,.... i.Z!!ili i ‘?y@~~;$,~ ;

. . . . . . . :. : . . .,, :

r : ‘:

,.r ; ,

.

End of Role 12.8 metres

Klohn-( r-ippcn

Klohn-Crippen

Abancionmenk And Restoration Plan j?nuary, l-996

Figure 4; Lupin Mine Final Tailings Estimate

Page 20

3.5. FREEZE BACK OF RECLAIMED TAILINGS AT NORTH RANKIN NICKEL MINE

Larry Dyke Geological Survey of Canada

Preliminary Report on Investigation of Reclaimed Tailings at Rankin Inlet, N.W.T.

L.D. Dyke, M. Douma, and C. Hyde Geological Survey of Canada, 601 Booth St., Ottawa, Ontario KIA OE8

Background

Between 1992 and 1994, tailings, originally produced by nickel ore concentration at Rankin Inlet, were excavated, re-deposited in the drained open pit portion of the mine workings, and covered with gravel. This operation was part of a program to render inert this potentially hazardous material. Sulphide minerals in the tailings consist mainly of pyrrhotite with lesser amounts of pentlandite and chalcopyrite. Ponds in the tailings impoundment area (Fig. 1) exhibited near-neutral pH but acidic conditions were recorded in ephemeral streams draining into the area. Dust from the tailings surface was a continuing nuisance and potential health hazard, while the land occupied by the tailings was desired for town expansion.

The reclamation program was funded by the federal Department of Indian and Northern Affairs and carried out by consultants and contractors under the direction of the territorial Department of Public Works. Tailings reclamation involved treatment and drainage of water filling the abandoned mine depression, backfilling of the depression with oxidized tailings, and placement of a grave1 caver over this and the remaining undisturbed tailings. An additional dike was constructed to supplement existing protection from wave erosion along the Hudson Bay shore. The expectation is that the reclaimed tailings Will become permanently frozen and protected from erosion by the grave1 cap and dikes. In late March, 1997, the Geological Survey of Canada (Larry Dyke, Martin Douma, and Christoff Hyde) and Queen’s University (Heather Jamieson and Joanna Meldrum) assisted DPW (Paul Erickson) in assessing both the progress of permafrost aggradation into the reclaimed tailings and chemical changes which may be taking place in the remaining unfrozen pore fluids as freezing advances.

Site Activities

The primary means of assessment was by air-rotary drilling. The objective of this drilling was to: 1. Allow installation of thermistor tables 2. Obtain cuttings samples of frozen and thawed tailings 3. Manually determine the depth of freeze-back 4. Obtain boreholes for electrical conductivity logging 5. Obtain boreholes to different depths in frozen tailings for subsequent tore sampling.

The air-rotary drilling was carried out in two stages over two days. Twenty five holes, 6.5 inches in diameter and ranging in depth from 1.5 to 3.5 m, were completed across the reclaimed tailings area. These holes were intended for subsequent collection of cores. Because rocks or metallic debris within the tailings would halt

coring, these holes were drilled in clusters to several depths to increase the likelihood of avoiding such obstructions. A further 7 boreholes were attempted to the bottom of the reclaimed tailings (Fig.2, Boreholes l-7). Although drilling could not continue into unfrozen tailings, casing was pushed and vibrated below the top of the unfrozen zone, meeting refusa1 due to the rock bottom or debris at depths between 6 and 12 m. These boreholes and one 18 m borehole through remaining undisturbed tailings, till, and bedrock (Fig. 2, Borehole 8) were logged for electrical conductivity. Thermistor tables were installed in the borehole penetrating bedrock (to 16 m) and in the two deepest boreholes in the reclaimed tailings (to 8 and 11 m).

Electrical conductivity (EM) surveys were also carried out over the surface of the reclaimed tailings and over part of the re,maining undisturbed tailings. The two instruments used allowed apparent conductivities to be recorded over a range of depths between about 2 and 30 m across. the 200 x 300 m grid area. The primary objective of this survey is to provide a means of extending borehole data on the thickness of the frozen and unfrozen parts of the reclaimed tailings.

Due partly to a delay in the arriva1 of equipment and to poor weather, coring was carried out in only one of the shallow boreholes. However, the cuttings samples from all levels in the frozen part of the reclaimed tailings, as well as limited sampling from within the unfrozen tailings, and tore from the top of the frozen tailings, Will permit a preliminary analysis of pore water chemical evolution accompanying freeze- back. The site Will be revisited in late-May to collect at least one complete tore through frozen tailings. All samples were shipped to Queen’s University in the condition collected and Will be analyzed there and at GSC for mineralogy and pore fluid composition.

Results

Cuttings samples were collected from the series of shallow holes. Several samples of thawed tailings and associated pore water were collected from the series of deeper holes. The water is highly saline with an electrical conductivity of about 50,000 umhos/cm and a pH ranging between about 5.5 and 7. One piezometer was installed, showing a static fluid level of 2.5 m below the ground surface. This level was also reached by fluid leaking into the casing of two of the deeper boreholes. These water levels are lower than would be expected if consolidation were actively taking place. Given that they appear to be at an elevation approximately equal to sea level, the remaining unfrozen part of the tailings may be hydraulically connected with the ocean.

Drilling and ground temperature measurements indicate that the tailings were ice-bonded to a depth of about 4 m, as of March 31, 1997. TO this depth the temperature warmed steadily to about -4OC and continued to warm gradually to about -1.5OC at a depth of 11 m (Fig. 3). Thus the tailings are partially frozen between about 4 and 6 m, or between temperatures of about -4 and -2OC, and completely unfrozen below a depth of 6 m or above a temperature of -2OC. Even below -4OC

there may be a considerable fraction of unfrozen fluid. These observations are confirmed by electrical conductivity logging of the deep borehole series, whereby conductivity in general increases between depths of about 4 and 6 m, reflecting the contribution to conductivity of increasing unfrozen water content (Fig. 4). Although no determination of pore water salinity has yet been made, the apparent freezing point depression in the reclaimed tailings suggests a pore water salinity roughly that of sea water, i.e. about 30 parts per thousand.

Ultimately, the reclaimed tailings should fall to a temperature of about -7OC. This is suggested by the temperature profile for the borehole placed outside the reclaimed tailings area (Borehole 8 in Fig. 2) where ground temperatures are probably in equilibrium with the climate. The time taken for the reclaimed tailings to completely freeze Will be included in the final report for this project. It is dependent on the thermal conductivity of frozen tailings and on any increase in unfrozen pore water salinity which may accompany continued freeze-back. Increases in pore water salinity to date should be revealed by pore water chemistry analyses which are to be carried out on samples presently in hand.

Surface EM surveys outlined a high conductivity area coincident with the reclaimed tailings area. Presumably the high conductivities are associated with the unfrozen part of the tailings. An interpretation of the survey data Will allow the thickness of this unfrozen part to be determined over the entire reclaimed tailings area. The part of the survey extended over adjacent undisturbed tailings showed a circular zone of negative readings surrounded by a zone of very high positive readings. This also awaits interpretation but the circular pattern may reflect the original depositional pattern of this part of the tailings and segregation of conductive sulphide minerals down the sides of a tailings spoil pile.

Scale in Metres

Fig. 1. Distribution of tailings prior to reclamation. Thickest tailings are immediately inland from Tailings Pond with thicknesses up to about 4 m. Beyond that area, tailings rapidly decrease in thickness to less than 0.5 m. Tailings Pond and Shallow Pond were both 0.5 m or less deep. Deep Pond was up to 10 m deep.

Scale in Metres

Outline of Deep Pond

Fig. 2. Enlargement of area receiving reclaimed tailings showing new dike and inundation of Shallow Pond by the ocean. Black dots show location of cased boreholes. Boreholes l-7 are located in the former site of Deep Pond in which the reclaimed tailings are held. Borehole 8 is located in unrecovered tailings.

I

Reclaimed

)r Unrecovered 8 :

Tailings --d I

i l I I

-10 Temperature, “C

Fig. 3. Subsurface temperatures on March 29, 1997 in reclaimed tailings (Boreholes 1 and 6) and in area where undisturbed tailings remain (Borehole 8).

2

Borehole: 4 mS/m

Fig. 4. Electrical conductivity logging of boreholes l-8 as shown in Fig. 2. Note logarithmic scale for conductivity (mS/m). Increase in conductivity in the Upper 4 m for boreholes l-7 is probably caused by the increasing content of saline pore water in the tailings. Conductivity peak in borehole 8 is probably due to unrecovered tailings.

3.6. LEACHING CHARACTERISTICS OF CULLATON LAKE TAILINGS

Nand Davé Natural Resources Canada - CANMET

.

? . c4

A z W

E E a

Cullaton Lake MEND Permafrost Workshop Edmonton, May 5, 1997

Objectives:

l TO evaluate oxidation and leaching characteristics of Cullaton Lake B and S- Zone tailings at:

+ 25 OC 2 OC and 10 OC

+ Acid Rock Drainage is an issue as the orebodies contained pyrite, pyrrhotite and other sulphide and metal bearing minerals

+ Preparation of final decommissioning plan etc.

CANMET, Elliot Lake Laboratory 2

Cullaton Lake MEND Permafrost Workshop Edmonton, May 5, 1997

Site Location:

. District of Nunavut and Keewatin sub-district, Northwest Territories

. Located 416 Km northwest of Churchill, Manitoba

. Site is at tree line and in the zone of continuous to wide spread discontinuous permafrost

. Cullaton Lake Gold Mines Ltd. (Company) operated 300 tonnes gold mil1 from October 1981 to August 1985.

l Ore from two distinct orebodies, B - and Shear (S) - Zones

. Total of 373,000 tonnes milled, 150,OO from B - zone and the balance 223,000 tonnes from S - zone

CANMET, Elliot Lake Laboratory 3

39

hale Cave

BAY

300 *m / I

CULLATON LAKE DISTRICT OF NUNAVUT - KEEWATIN, N.W.T

KEY PLAN

Fig. 1 Location of Cullaton Lake mine, Northwest Territories.

40

CULLATON LAKE

-0 \ \

/c GEOLOGY œ

cs*m

Fig. 2 Location of B- and Shear-Zones at the Cullaton Lake mine property.

Cullaton Lake MEND Permafrost Workshop Edmonton, May 5, 1997

B - Zone:

b Gold bearing iron formation in a turbiditic sedimentary basin which formed part of the Rankin Inlet - Ennadi Archean greenstone belt in the Keewatin district of Nunavut (NWT).

Shear (S) - Zone

b Gold occurred in fractured and sheared orthoquartzite . Mineralization in altered shears, breccia zones, pyritic shears, and pyritic impure quartzite.

CANMET, Elliot Lake Laboratory

142

Table 1. Physicai characteristics of B and Shear (S) - Zones tailings.

Parameter B - Zone Shear (S) Zone

Colour Greenish grey Brownish orange

Texture sandy silt sandy silt

Particle size 70% less than 100 prn 50% less than 100 prn

ho 65 prn 100 prn

ho 35 prn 45 prn

Moisture content (% wt) 9.3 9.5

Wet bulk density (tonne / m3) 1.80 1.58

Grain density (tonne / m3) 3.00 2.50

Porosity (%) 40 36.8

Wet mass of tailings in Column (kg) 9.7 9.7

Total bulk volume dry tailings (1) 4.89 5.56

Total pore volume dry tailings (1) 1.95 2.05

% pore volume moisture saturation 46 45

143

Table 2. Chemical characteristics of B and Shear (S) - Zones tailings. Ail concentration values are given in percentiles, except where noted.

Parameter / Element B - Zone Shear (S) Zone

Al (%) Ba O@h$ Ca (%)

cd (IN@ CO o4z.k) cr Wg) CU Wg/g) Fe (%) K (W Mg @JO) Mn m Na (%) Ni hz.&> Total phosphorus (% P) Pb a-k) Total sulphur ( % S) Soluble sulphur ( as % S) Total sulphide sulphur ( as % S) Ti (%) v Wg/g) zn wid a- Q4&9 Total acid generation potential, kg CaCO3/tonne Total alkalinity, kg CaCOdtonne Net neutralization potential, kg CaCO&onne

1.62 f 0.008 0.47 f 0.003 83.6 f 0.6 101.5 f 0.8

2.37 f 0.032 0.09 f 0.002 <lO <lO <lO 16.1 f 0.52

36.4 f 0.2 24.4 f 0.2 45.4 f 0.3 15.5 f 0.3

20.07 i 0.085 2.96 f 0.01 0.305 i 0.07 0.15 f 0.025 0.88 f 0.006 0.057 f 0.003 0.09 f 0.0003 0.01 f 0.0001 0.14 f 0.001 0.06 f 0.002 60.6 f 10.8 48.6 f 1.1

0.06 f 0.014 0.009 i 0.006 65.8 f 1.9 48.4 f 0.9 2.63 f 0.32 0.49 i 0.1 0.32 f 0.01 0.09 f 0.01 2.31 f 0.33 0.4f0.11

0.069 f 0.0008 0.012 f 0.0002 58.6 f 2.0 15.4 f 0.4 45.7 f 0.4 12.1 f 0.1 53.1 f 3.0 44.4 f 1.2

72.2 12.5

45.36 2.0 -26.84 - 10.5

Cullaton Lake MEND Permafrost Workshop Edmonton, May 5, 1997

Leaching Procedure:

. Leaching in cylindrical columns

l Inoculation of tailings with T-ferrooxidans culture in the columns

. Batch leaching using natural lake water (pH -6.8, acidity 3-5 mg/l, SO4 - 6-8 mg/l, etc. )

. Sampling at intervals of 1 to 2 weeks

l Effluent analyzed for pH, Eh, total potential acidity, total alkalinity, total sulphate, major metals and cyanide

. Cold temperature: placement in a walk in freezer maintained at the desired temperature( s)

CANMET, Elliot Lake Laboratory 5

41

Column vertical section

Fl2.5 cm-

80 cm

!

Fig. 3 Vertical section of a leaching column.

.................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... .................... ..................... ..................... .................... .................... ..................... ..................... .................... .................... ..................... ..................... .................... .................... ..................... ..................... .................... .................... .......... ..................... ........... .................... .................... ........... ..................... .......... .................... .................... .......... ..................... ........... Sand Sand Filter

Gravol Gravol Filtor

I

Tailings

42

B-Zone B-Zone S-Zone S-Zone

Fig. 4 Experimental arrangement of leaching colwnns.

LYSIMETER COLUMN TEST pH COLUMN B ZONE

2 i I

11 I

+

. _ m

+++++ +++‘+‘+y+--’

-

ml-I

I I I 1

0 50 100 150 200 250 TIME (DAYS)

c l--

- PH-1 + PH-2 - PH-AK

Fig. 8 - Effluent pH for B Zone columns.

10000

8000 î \

r 6000 w

k 4000

2 2000

0

LYSIMETER COLUMN TEST ACIDITY COLUMN B ZONE

0 50 100 150 200 250 TIME (DAY~)

l - ACID-1 + ACID-2 - ACID,AVG 1

Fig. II - Effluent acidity for B Zone columns.

LYSIMETER COLUMN TEST SULPHATE COLUMN B ZONE

0 50 100 TIME

150 @A~S)

- SULF-1 + SULF-2 - SULF-AVG ----

Fig. 13 - Effluent total sulphate (SO4 -*) concentration for B Zone columns.

250

5000

î 4000 k E - 3000 0 E!s

I 2000 8

0

l-

LYSIMETER COLUMN TEST FE-TOT COLUMN B ZONE

1

0 50 100 150 200 250 TIME (DAYS)

I - FE-TOT- 1 + FE-TOT-2 - FLTOLAVG (

Fig. 14 - Effluent total iron (Fe) concentration for B Zone columns.

x P

10.00

8.00

6.00

4.00

2.00

0.00

Cullaton Lake - B-Zone at 2 OC pH vs. Time

Time, years

b Cold Temp. Avg.-pH e Room Temp. Avg.-pH

P

Fig. 6a B - Zone: effluent pJ-I’s at 2 “C and room temperature.

Cullaton Lake - B-Zone at 10 OC pH vs. Time

8.00

6.00

-J-J -L

4.00 --

2.00

0.00 8

1994

Time, years 1996

I - Cold Temp. Avg.-pH - Room Temp. Avg.-pH 1 I I

Fig. 6b B - Zone: effluent pH’s at 10 “C and room temperature.

Cullaton Lake - B-Zone at 2 OC Acidity vs. Time

1000.00

800.00

800.00

400.00

200.00

0.00

1992

Time, years

l - B-Zone 1Acidity _Q_ B-Zone î_Acidity - AverageAcidity

Fig. 9a B - Zone: effluent total acidity at 2 “C.

Cullaton Lake - B-Zone at 10 OC Acidity vs. Time

1000

800

600

400

200

0 r-

l-

1994 1995

Time, years

- B-Zone 1Acidity - B-Zone 2 Acidity -- AverageAcidity

1996

Fig. 9b B - Zone: effluent total acidity at 10 “C.

20000 -

Cullaton Lake - B-Zone at 2 OC Sulphate Concentration vs. Time

16000 r=

E 12000 ai ti; E p. 8000

z 4000

---..

Time, years 1995

- B-Zone l_Sulphate - B-Zone 2-Sulphate ----+-- Average-Sulphate I

P

Fig. 1 la B - Zone: effluent dissolved sulphate concentration at 2 “C.

500

400 r=

- 300

8 5 200 8 z

100

0

Cullaton Lake - B-Zone at 2 OC Total Iron Concentration vs. Time

1992

Tjme, years

I - B-Zone l-Total Iran - B-Zone 2-Total Iran -----+- Average-Total Iron

Fig. 14a B - Zone: effluent dissolved total iron concentration at 2 “C.

62

i

t +

! l

10

9

8

7

I: 6 n5

4

3

2

1

LYSIMETER COLUMN TEST pH COLUMN S ZONE

0 50 100 150 200 250 -ME (DAY~)

I - PH-1 + PH-2 - PH-AVG ( l-- -_-- --

Fig. 26 - Effluent pH for S Zone colwms.

62

1 t 1 Y : 1 m

1 1 1 e

\ t t

(7/W

uaw

Cullaton Lake - S-Zone at 2 OC pH vs. Time

10.00

8.00

6.00

4.00

2.00

0.00

1992 1993

Time, years

1

1994 1995

----a-- Cold Temp. Avg.-pH -u---- Room Temp. Avg.-pH

8

Fig. 30a S - Zone: effluent pH’s at 2 “C and room temperature.

10.00

8.00

6.00 x P

4.00

2.00

0.00 l-

Ï

1994

Cullaton Lake - S-Zone at 10 OC pH vs. Time

1995

Time, years

1996

I ---- Cold Temp. Avg.-pH -+-- Room Temp. Avg.-pH 1 I I

Fig. 30b S - Zone: effluent pH’s at 10 “C and room temperature.

Acid

ity,

mg/

1 as

CaC

03

2 B C

0

I

I Q

l m

l

l

3

0 0 b

.I

m

8

:

l

l

El i

0 n

0*m

-;

96

Cullatoq Lake - S-Zone at 7 0 OC Acidity vs. Time

1000.00

800.00

600.00

400.00

200.00

0.00

1994

I I

1995

Time, years

--

--

l--

- S-Zone 1Acidity - S-Zone 2-Acidity - Average-Acidity

-

1996

Fig. 33b S - Zone: effluent total acidity at 10 “C.

Cullaton Lake MEND Permafrost Workshop Edmonton, May 5, 1997

Results: . Both B and S - Zones tailings have low sulphide contents

(2.4 and 0.5 % S, respectively)

. Negative NNP (-3 1.6 and -14.3 Kg CaCO&onne) and hence acid generating

. ARD more pronounced for B - zone then S - zone at 25 OC

. At 2 OC the acid generation rate is low providing a longer neutralization period and delayed ARD for B- zone than S- zone

. Upon freeze thaw continuity of ARD cesses

. At 10 OC some initial ARD occurs, but in a11 cases the high moisture retention characteristics of the tailings controls the duration of ARD

CANMET, Elliot Lake Laboratory 6

Cullaton Lake MEND Permafrost Workshop Edmonton, May 5,1997

Results: . Calculated rate of acid generation at 2 OC for B - Zone

tailings is approximately 10% of that at 25 OC, which is comparable to reported value of - 16%

. Lowering of tailings temperature would delay occurrence of ARD but would not prevent it unless porewater is permanently frozen

CANMET, Elliot Lake Laboratory 7

Oxygen Concentration In Tailings (Unsaturated) No Cover: Air Fllled Pore Space

300.00

250.00

Ë & 200.00 c

0 .-

g Q> 150.00 c s 5 ; 100.00 0

50.00

0.00 0.00 0.50 1.00 1.50

Depth Tailings, m

Figure 4.1 Oxygen concentration profiles as a function of depth at 25”, 4”, and 0°C in unsaturated tailings (air filled pore spaces) without caver. The air/tailings interface is at 0 m.

16.00

14.00

"E s 12.00 .

0 .- f 10.00

Q 8 8.00 s

if 0 6.00 F 2

% 4.00 .- a

2.00

0.00

Oxygen Concentration in Tailings (Saturated) No Cover : Water Fllled Pore Space

L t c/ T=o”C * F k T=4"C

1. / :

T=25%

I 0.500

I 1 1 I I 1.000 1.500 2.000 2.500 3.000

Depth Tailings, m

Figure 4.2 Dissolved oxygen concentration profiles as a function of depth at 25”, 4”, and 0°C in saturated tailings (water filled pore spaces) with no additional caver. The airkailings interface is at 0 m.

16.00

14.00

Ë 3 12.00 0.

E .- H 10.00

fi

s 8.00 E

E 0 6.00

% 8 9 4.00 0

2.00

0.00

Oxygen Concentration in Tailings (Saturated) No Cover: Water Fllled Pore Space

\ * .

\ ‘\ \. 'y

T=O"C

r 0.000 0.020 0.040 0.060 0.080 0.100 0.120 0.140 0.160 0.180 0.200

Depth Tallings, m

Figure 4.3 Dissolved oxygen concentration profiles (expanded scale) as a function of depth at 25”, 4”, and 0°C in saturated tailings (water filled pore spaces) with no additiqnal caver. The air/tailings interface is at0 m.

16.00

14.00

“E a 12.00 c

.- E 10.00

i

8 8.00 c El R 0 6.00

1 E: p 4.00

2.00

0.00

Oxygen Concentration Profiles 1 m Water Cover (Stagnant) on Tailings

. ‘-\ T = 0 “C . \ .

, Interface

\

. T=25”C ‘\ =. / . -

Tailings

0.000 0.500 1.000 1.500 2.000 2.500 3.000

Depth Water Cover / Tailings , m

Figure 4.4 Dissolved oxygen concentration profiles as a function of depth at 25”, 4”, and 0°C in unmixed water caver of depth 1 m and underwater deposited tailings. The tailings-water interface is at depth 1.0 m from the surface of the water caver.

Oxygen Concentration Profiles 1 m Water Cover (Weil Mixed) on Tailings

16.00

14.00

“f 1200 cn . e 0 .- L 10.00

fi

s 8.00 8

E 0 6.00

3

55 .- 4.00 0

2.00

0.00

-.----....-..-----.-------, T=O”C . I

Interface

Water Tailings

0.000 1 .ooo 1.500 2.000

Depth Water Cover / Taillngs, m

Figure 4.6 Dissolved oxygen concentration profiles as a function of depth at 25”, 4”, and 0°C in a well mixed water caver of depth 1 m and underwater deposited tailings. The tailings-water interface is at depth 1 .O m from the surface of the water caver.

hoO ) sOI X 89'8 (3oO ) 82-Z Pa+l l]aM PU2

CM ) SOI x 19-L (3oP 1 09-z aq..xatuf av ahoq= tu 1 IaleM (3052) 501 x L9’S (3oSZ) 6P’C JO qdap :atsaM paJaAo3 laltzh :ç as83

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3.7. SUMMARY OF CURRENT RESEARCH WORK ON TAILINGS

Dave Sego Univers@ of Alberta

,,..

<’ .,<

‘,,:‘;

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.‘, .:, Outline of presentation: ‘,‘,, :,’ ,:., .,a:, .‘,

l Objective of research study ,::, :,: ‘,,

l Laboratory test program ,:

* Test equipment and pkeliminary restiks ,::, ,I l Physical and chemical properties .,,: l Consolidatiok and hydraulic &nductivity :::: l Unfrozen water content Vers$ temperature l Thermal conductivity versus temperature l Frost heave

. ’

.: _’

::,

.,’

.’

Objective of research carried out: ,“:; ,’ .:’ ,, ::. : 2% measurti thk effects of pore water ch’knistry and ; .,’ s#lfldes on the:~unfioz@n water content ‘bf saturated ‘,’ @&$g& ” 1,:

;

‘:), ,: Ne& for &&ar$ to be &rried ol,& ,’ ’ .< .;: ;,: ,:I:, :::, ,;

The thermal and hydraulic flow properties of freezing ,:,;,: I,. and froztin ttiilings are strongly influen&d by amount ..:: of unfrozen tiater in ttiilings ut tempera&res below freezing point.

.., :::< :: ‘.’ .::

Proposed test (program: _:/ .,, ‘; ‘< : ‘.’ : The following test to be carried out &ti each ,.,::.< &kliggs afid. &h different fluids su&li&j. :’ :::,

Physical characterizatio,n (grain size dktribution, .., ,y: specific gravity, titterberg limits, mitieral0g.y) Chemictil chatiacterizatioi ( pH, cori&@ivity, acid ,‘, base aCcou’nting,ore wafer sulfates).: ,‘, ../,./ .._.,,.,.,,. j ̂ . ,,.“, <. ;:: I, Saturat&dflow and defor&:atio,k charkteristics of ‘. unfrozkn and frozeti samples (consol@tion and .’ hydraulic Conductivity) ., :’ ‘> ., ;‘:. Unfrozen water content versus tempekzture ,’ Thermal conductivity versus temperatbe ,’ ,:.. .?,’ Frost heave test 8: ,,,:. : :,

‘.

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: ,:

: ‘.:a:

Physkal and chemical propbfties .; ,‘,’

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COMPRESSIBILITY OF CRUMBS wDRAuLIc &~~CTIVITY OF CRUMBS 1.G I

o Pore Fluid-Wa., l-4- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . \ l Pore Fluid-Water+sediment . . . . . . . T,‘..........

1.2 1 0 i 1, .: ;

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L i ‘1 1.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . r.-i . . . . . jj.? . . . . < . . . . . . . . . . . . . 9.?$I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -1

: : o**- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . . . . 7 _.__._____._._........ j... . . . . . . . . . . . . . . . . . . . . . . . . . . . - ) ‘.

O,*F . ..-..................................... !:y.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..- J ; : :, j ; : ,.,: ! .

0.6~ . . . ..___.__.................. i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . j . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..- O.6- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . f.:: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . + . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..- j ::,, . <’ , /‘, : ,‘*, i 0.4- . . . .._._._..._............... i . ..___........................... i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . y. . . . . . . . . . . . . . . . . . . . . . . . ..-

: ‘,’ ., ” 0*4- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .i.; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 i:,.. j.’ j %‘<

i:;‘: ; 0.2L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . i . . . . . . . . . . . . . . . . . . . $......i...: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f...... . . . . . . . . . . . . . . . . . . ..- 0.2- : ,‘:

i : ‘8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,......-..“.................,............ I”““” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~

‘1 I i ;:,

0.0. * * **..**’ 2,’ ::, I

I I 10” 10” 10’ loa

au 0.0 10’ 10” *(y ; 10” 10‘2

Effective Stress (@a) .’

Hydraulic Conductivity (cm/s)

A.. : +.

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- - . . . . . . . (

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COMPRESSIBILITYOFLUPIN PORE FLUID-LUPIN WATER

IIYDRAULIC 'CONDUCTIVITY 0~ LUPIN PORE FiJJID-LUPIN WATER

. . . . . Ll 0 SN@~ #3 : .‘.., .‘, i.,:,

l i l Saru&M . _ i, .;,

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0

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o,61 ._.._........................ t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..-

i

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10-l 10” ; 10’ 102 103 Effective Stress (M>a)

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: ,‘. ,. I ::,‘, i ,. i

l- i, 0.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . k .,,....................................

i ,.:

-3

:,: Hydraulic Conductivity (MI/S)

,,:Y;’ :; : ‘. ‘,,.‘, ,. .; ,:‘. ”

:: ::,

COMPRESSIilILITY OF LUPIN HYrmuLrc CONDUCTIVITY OF LUPIN PORE FLUIDiD. ISTILLED WAT.ER PORE FLUIIkDISTILLED WATER

1.4 ! 1’ ’ ’ ‘“‘“! : :.:I ;:,;:: : !

i **2- . .._......................... / . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i...

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1.0 0 i, -................: . . . . . . . . . . . . 1”“” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . .._........_..........- i ,‘.. :,, 0 !

: 0 ,0 :: l.O- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 . . . . 2.i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1’........................................-

,i . . :‘:,q o / i : : .., 8 I

0.8- . . . . . . . . . . . . . . . . . . ?. . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . :‘...... i . . . . . . . . . . . . . . . . . . . . . . 0 . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . ..- ,:,,

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: : Oa4L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i..............................-

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content versus tdnperature ,< : ;::: ‘, ‘, , ::, ,’ :. ,.‘, ; .’ ,;: -_,: ‘, ,’ :;: ::, j ‘, ,’ y’, .’ j .;.,,: ,:,,’ .:: : ‘. :, ‘,y, .,<’ :: :,, ..’ ;_ .,:j- .:.; ‘,’ ‘,:/, ::. :<:, ::; ;. t ,,,’ ;:

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1. . . . .

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ci 8 0;

Apparent Dielsctric Constant versus Temperature

g 14.0

Y 3 13.0

2 12.0,

8 11.0 i 0 E 10.0 --

9 --

.d '

9.0

3 80-- .- Y 7.0 -- B 2 6.0 --

5.0 --

4.0 --

3.0 --

2.0 --

+ Wellgreen Crumbs - water+sediment

n Wellgreen Slab - water+sedimeiit

A Lupin

f

i

-90.0 -80.0 -70.0 -60.0 -50.0 -40.0 -30.0 -20.0 -10.0

Temperature (Celcius)

0.34 ,

Unfrozen Volumetric Water Content versus Teniperature (Smith ad Tice, 1988)

0.32

# 0.30 b

+ Wellgreen Crumbs - water+sediment 0.28 -A n Wellgreen Slab - water+sediment 0.26 -A

[ A Lupin 0.24 --

0.22 -- :

0.20 -- 0.18 -i +

0.16 -- + 0.14 --

0.12 -- f 0.10 -- 0.08 --

+ # 0.06 -- :a 0.04 -- m h

-20.0 -18.0 -16.0 -14.0 -12.0 -10.0 -8.0

Temperature (Celcius)

-6.0 .’ ‘-4.0 -2.0 0.0

Apparent Dielectric Constant versus Temperatlire ‘.i< <, ;;

20.0 1 .:: :,: + Wellgreen Crumbs - water

l 1. ,, ‘, ‘.,, :: n Wellgreen Slab - water <’ _. .: A Control sample, ‘5; .,:. .‘. : :, :,.<,

,’ ‘,I '7,. WeIlgreen Crumbs at 22.0:"C kaq34 ,:.', <. : Wellgreen Slab at 22.0 "CI, ka=37 :,' ,: Control sample at 22.0 "C ka=23 ::,

,. .'. 4 ,'.

A

:

AA

-20.0 -19.0 -18.0 -17.0 -16.0 -15.0 -14.0 -13.0 -12.0 -11.0 -10.0 -9.0 -8.0 -7.0 -6.0 ,'i5.8 -4.0 -3.0 -2.0 -1.0 0.0

Temperature (“C) ,:j, ‘,, ,’ ,

Volumetric Water Content versus Temperature

0.35 ,

0.30 --

2 0.25 --

c1 E z 3 0.20 -A 5 0: 8

f 0.15 -- 3

E

g 0.10 --

0.05 --

Wellgreen Crumbs at 22.0 "C 8~0.62 Wellgreen Slab at 22.0 "C 6=0.66 Control sample at 22.0 "C 8=0.42

o.ooL : ’ : ’ :A’ : ‘: ’ : ’ ; ’ : ’ :A’ : ’ : ’ : ’ : ‘: ’ :a’ : ’ :y4 ‘: ’ -20.0 -19.0 -18.0 -17.0 -16.0 -15.0 -14.0 -13.0 -12.0 -11.0 -10.0 -9.0 -8.0 -7.0 -6.0 'k.0 -4.0 -3.0 -2.0 -1.0 0.0

Temperature (“C)

4

1 soi1 specisnen 2 B4att.m ca* Ports 3 Top Cdat Ports 4 RTD chdiets 5 I$dWm Drainage 6 LVDT 7 Ahospheric Port 8 WC Jacket 9 Teflon Liner 10 Load Piston 11 AIl Tbread Clamps 12 Aluminium Top Cap 13 Aluminium Bottom Pedestal 14 Load Guide Bar 15 PVC Base -:--1..

:. .~ j

Time (hrs)

WELLGREEN FROST I3EAVE Cruink + Water

Time (im)

fhg~~mmry of Test Results: .]. :, .,< ‘, <,,

C434343bsions ( .:. :, .‘, ,:., ;: .‘, ,, :.::;: !<

* lbtential exists for water niovement”in ftiozen :*., Bailings due to thermal potential, &ktrical ‘Y,, ptentikl tind ,chemical potential g&!li&nts. :.. ,:,

3.8. PERMAFROST: IMPLICATIONS FOR MINESITE-DRAINAGE CHEMISTRY

Kevin Morin Morwijck Enterprises

Pemafrost.

Implications for Minesite-Drainage Chemistry

Minesite Drainage Assessment Group

1

b A pyrite grain oxidixes, 1 generating acidity and heat.

Some heat is “absorbed” by the pyrite grain and surrounding

grains.

Some heat is conducted away by grains and porewater and/or carried away by

moving porewater

/Doer.myhert pyrite grain remain around the grain?

Temperature increases; rate of oxidation increases; Greater amount of heat is

generated.

Steady state; No change in temperature;

No change in rate of oxidation;

Temperature decreases; rate of oxidation decreases;

Less heat is generated.

1 No change in rate of heat generation. Ill

2

A Wyomig Bentonite, Natural B Kaolinite C Rust (Fe,O,) D Limonite E W. Lebanon Grave1 < 100 p F Fairbanks Silt

0.80-

0.60- A

0.40 -

h \ - 7

0.20-' %c '- .

Ep ' \

\ -' F A&.-*=- - - - 0.00

- --x-x+-- - I I I I I I I

0 -2 -4 -6 -8 -10 Temperature PC)

. .

.

P”“I’ ’

““‘1’ I

““‘1 I

I 1”“’

’ ’

’ ““1”

I “‘1”

I I

‘i Y

? 0

T cv

W

W

W

7 r

F z

z z

2 Y

7 r

Y

I I

I I

I I

I I

I I

I - 0

I Frozen Ground Thawed Ground

Vaporous Moisture

1 Outer Layer (Volumetric Moisture)

Intermediate Layer

Undissolving Volume

Solid Phase

Decreasing Temperature

6

12

10

8

6

4

0 I I I

20 40

Temperature (degrees Celsius)

60

7

30-

20-

1 o-

O-

-10

-2o-

-3o-

Tailings : : Lupin, 033 i .

: . . : : . .

. . . . . . . . . . . . . ..I...............S.......

: :

: :

: : . .

: : : : : :

. . . . . . . . . . . . . ..*...............*.m..... . .

: : . . : . . :

fi 1 M‘ -@-- 2M --A- 3M -*=- 4M -+- 5M

c / : .

. . .

: ;0 0 fi\ r ; ;

‘u i

: : : . : . . . . . . . . . . . . . . . . . . . . . . . . . . . \ : . . . . . . ..m...............*............... . . 0 : .

f : 3 -;=*-:> - : I HC . & .,2-,;*-+; 4 c

s . / 4

2

A+--~* ; . . ~ ./’ : : ,+ . . . : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \Y@...; . . . . . . . . . . . . ..I . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~................~...............~....................~ . . . . . . . ..+............... . . . . .

Jan

. . : : : : :

\

. : : : : : :

!Mar i May iJUl i Sep ;Nov :Jan 199 . . . . . . 120

l

10 Time In Days Since January 1, 1989

8

. /

,

/ c

I I

I

I-

l-

Humidity Ce11 Sample NHC-1 Sulphate Production Rate vs Time at

Ambient, +~OC and -2OOC

r , 14 ” \

, 1” /I I, / \ 1 \‘\

I . I 1 I

I I

1 I

E I *

Sep-89 Mar-90 Sep-90 Time

Mar-9 1 Sep-91

10

0.04

0.03

0.02

0.01

0.00

Humidity Ce11 Sample NHC-1 Zinc Leach rate vs Time at Ambient, + 6OC and -2OOC

Ambient - - - + 6 deg C - - - 20 deg C

4

I ’ / 1

,’ ‘,

I 1 ’ ’ I 1’ ’

I 1’ ’ I l

I

/~c----m-mm----J

I I I I I I I I I Sep-89 Mar-90 Sep-90

Time Mar-91 Sep-91

11

Humidity Ce11 Sample NHC-1 Copper Leach rate vs Time at Ambient, + 6OC and -2OOC

Ambient - - - + 6 deg C - - - 20 deg C

‘\ ’ \

4 \

\

\

\

\

\

I 1’

‘1 /

1’ \ /

\ / I I

\ / I I

I ’ l ’ d \ I I I

I I

I I

I I

I I

I f

\

Sep-89 Mar-90 Sep-90 Time

Mar-91 Sep-9 1

12

0.60 l

RE]LATIVE RATE QIF l3IQLOGICAL OXIDATION VERS'LJS TEMPERATURE

* /

0.40:

0.201 LEGEND A Malouf and Prater (1961) q Silverman and Lundgren (1958) * Belly and Brock (1974)

- RATAP Equation 0.00 I I I I I I I I II II II II III 1 III II III1 1 III III Ill 1

0.00 10.00 20.00 30.00 40.00

TEMPERATURE (CELSIUS) 13

THIOBACILLUS

Kahn (1987) reported on slow-growing Thiobacillus at the Nanisivik Mine that had apparently acclimatized to cold temperatures and would generally not reproduce at a warmer temperature of 120C It is possible that T. ferrooxidans could adapt to unusual conditions, perhaps even to sub-zero temperatures when sufficient oxygen and unfrozen water are present.

14

NWT MASSIVE-SULPHIDE DEPOSITS

. PricolaT,ake-480 km northeast of Yellowknife u

(Cameron, 1977); continuous permafrost; “intensive” sulphide oxidation near surface and at depth; natural acidic drainage and metal leaching with pH as low as 2.4; jarosite minerals.

. . elville Penmsula.: continuous permafrost (Cameron, 1979); pH as low as 3.1; active layer roughly 1 m thick, but oxidation believed occurring to tens of meters; attributed to graphite and/or sulphide minerals acting as inert conductors of electrons, which passed from the deep sulphide minerals to

atmospheric oxygen.

15

CAMERON (1977):

“Permafrost is no deterrent to active oxidation of sulphide bodies. In fact O2 is more soluble in cold water and the exothermic nature of many oxidation processes provides a continuing energy source. In frozen ground, thin, intergranular water films allow chemical processes to be active, even in win ter.... The presence of Springs and sink holes in the vicinity of the mineralization show that taliks (thawed channels) exist in the permafrost.”

16

I I :i’ I /

El

I

J f

1 I I

I I

I I

I A

0 v-4

m

-% 0

-m

-zi

-0 H

-0

b c c-4

3.9. A MODEL FOR PERMAFROST FORMATION IN WASTE ROCK PILES AT THE BHP DIAMONDS PROJECT

Don Hayley EBA Engineering Ltd.

A Mode1 For Permafrost Formation In Waste Rock Dumps

BHP, NWT Diamonds Project

by : Don Hayley Wim Van Gassen Edward Gu

- - - - - - -Koala 1993 measurements

-Koala 1994 measurements

+Koala 1993 mean monthly

+Koala 1994 mean monthly

+Koala long-term mean monthly (interpolated)

+ Lupin 1993-94 mean monthly

+ Lupin long-term mean

Feb Mar Apr May Jun Jul Aug SP oct Nov Dec Jan

Month

Climate at Lac de Gras

Dump Characteristics

l Granite l sand to 2 m boulders l 2 mg/m3dry density l 1 % water content

l Foundation l Rock or Till l Permafrost G3 -5OC

TABLE 1 MATERIAL PROPERTIES IN THERMAL ANALYSfS FOR BHP WASTE DUMPS

MATERIAL

Water Content vo)

WASTE ROCK SATURATED FOUNDATION WASTE ROCK TILL

1.0 12.0 8.0

Frozen Dry Density &glm31

2,000 2,000 2.100

Unfrozen Dry Density (kg/m’I

2,000 2,000 2,100

Clay Fraction (%)

0.0 0.0 0.0

Frozen Thermal conductivity (W/mC”)

0.94 2.89 2.03

Unfrozen Thermal conductivity (W/mC3

0.60 2.10 1.70

Bulk Density (kglm’)

2,020 2,240 2,270

Frozen Specific Heat (KJlkg C”)

0.75 0.88 0.83

Unfrozen Specific Heat (KJlkg CO)

Latent Heat (M Jlm’)

0.77 1.10 0.99

-7.0 -80.0 -56.0

Material Properties

Construction Sequence

l 2 m thick lifts

l 20 m total height in 3 years

l Rock at bottom placed @ -5°C

l Rock at top placed @ -O.!S°C

l Construction sequence modeled in 10 temperature steps

l Dump temperature at end of construction -!Soc except at top

E ï a Q

20.0

10.0

0.0

.lO.O -

A 7

.

-30.0 -15.0 0.0 Temperature

Dump Temperature, End Of Construction

Water Impacts

l 300 mm annual precipitation; 50 % falls as snow

l Assume about half Will infiltrate the clump l 40 % of the snow l 60 % of the rain l 150 mm total

l Snowmelt infiltrates in 6-10 mm daily episodes (60 mm)

l Rainfall infiltrates as 9- 10 mm episodes over 10 days (90 mm)

l Drops to the bottom saturating a 40 mm high portion of the rockfill (porosity of 25%)

l Water percolates slowly toward dump perimeter

l How far Will it travel before it freezes?

I 3

. .

. A

Retention Time

l Initial hydraulic gradient 2%

l Hydraulic conductivity 5 x 104 mkec

l Seepage velocity from Darcy’s Law - 3.6 m/hr

l Water is typically retained for several days

p- \Y\Y//-T\\ c -2%

bA \ SE

J

100

80

60

40

20

0

10 mm water infiltration per day from thawing snow for 6 days

1 -Jun 2-Jun 3-Jun 4-Jun 5Jun 6-Jun

Date

Freezing Time For Snowmelt

frein thawing snow results

80

60

10 mm water infiltration per 10 day from summer rains for 90 days

0 6-Jun 15Jun 25-Jun 5-Jul 15-Jul 25-Jul 5-Aug 15-Aug 25-Aug 5-Sep

Date

Freezing Time For Rain

400

3.50

300

250

200

150

100

50

0

l I I i = 0.02. k = 0.05 m/sec I I I

t I- i = 0.01, k = 0.05 m/sec I I II

I-Jun 2-Jun 3-Jun 4-Jun 5-Jun 6-Jun

Date

FLOW DISTANCE BEFORE FREEZING DURING SNOW THAWING

i I I I

I

-30.0 -15.0 0.0 Tempature(“C)

Freezing Rate Predictions

’ 400

350

300

2.50

200

150

100

50

l I I l I l

Y i = 0.02, k = 0.05 m/sec

i = 0.01, k = 0.05 m/sec 1

f -- Start with unfrozen water from thawing snow results

” ~~~ 1 I I I I 1 I I I I

6-Jun 15-Jun 2%Jun 5-Jul 15-Jul 25-Jul 5-Aug I5-Aug 25-Aug 5-Sep

Date

FLOW DISTANCE BEFORE FREEZING DURING SUMMER RAINS

Exfiltration fringe

Results

about 150 m wide

l An ice saturated tore Will form at the rate of 600 mm/yr

l The tore Will gradually increase the graciient and seepage velocity

l Eventually all the infiltration (150 mm/ m2) Will exfiltrate through the fringe:

l The tore Will remain frozen and ice saturated.

Optimization Options

A berm of finer grained rock around perimeter l Increased retention time l decrease fringe width

Selectively place ARD potential rock in the tore zone

Increase surface slope and decrease lift thickness.

Enhance saturation rate by adding water

Research Priorities

l Temperature profile within dumps l Fox dump C3 Koala

l Confirmation of ice saturation l Insitu permeability l Geophysics (GPR)

l Careful site observations

3.10. RESEARCH PRIORITIES FOR NORTHERN ARD

Stephen Day Norecol Dames & Moore

W

z 0

l Significani Producing or Closed

1. Whitehorse Copper 10. Lupin 2. Mt. Nansen il. Salmita 3. Keno Hill 12. Giaque Lake 4. Faro 13. Con, Giant 5. Ketza River 14. Pine Point 6. Sa Dena Hes 15. Rankin 7. Cantung 16. Cullaton Lake 8. Port Radium 17. Polaris

9. Terra Mines 18. Nanisivik /

FIGURE 1 GEOLOGICAL SUB-REGIONS

/&RDILLERAEI~, L, EAST j

l i6

TINTINA FAULT Geologitial Survey of Canada, 197

12\26663-SWG-1 Z@&NORECOL, D~ivas af MOORE, INC.

c

l Significant Producing or Closed Mines 1. Whitehorse Copper 10. Lupin 2. Mt. Nansen Ii. Salmita

P 3. Keno Hill 12. Giaque Lake

4. Faro 13.

5. Ketza River 14. Pine Point 6. Sa Dena Hes 15. 7. Cantung 16. 8. Port Radium 17. 9. -. Terra Mines __.. - ..__ 18. Con, Giant /

Rankin Cullaton Lake Polaris \ Nanisivik

-7 A

312\26663-3\FIG-2

Nationpl...Atlas of Canada (1974) . I -

NORECOL, DAMES & MOORE,INC.

,o Signlficant Producing or Closed Mines 1. Whitehorse Coppet 10. Lupin 2. Mt. Nansen 11. Salmita 3. Keno Hill 12. Giaque Lake 4. Faro 13. Con, Giant 5. Ketza River 14. Pine Point 6. Sa Dena Hes 15. Rankin 7. Cantung 16. Cullaton Lake 8. Port Radium 17. Polaris 9~ Terra Mines 18. Nanisivik /

Geological Survey of Canada (1967) _ ..* 8

- 312\26663-3\FIG-3 NORECOL,DAhfES & MOORE,INC.

P (MEAN

FIGURE 3 'ERMAFROST AIR TEMPERATURE)

l Significant Prodt

1. Whitehorse Coppet 2. Mt. Nansen 3. Keno Hill 4. Faro 5. Ketza River 6. Sa Dena Hes 7. Cantung 8. Port Radium 9. Terra Mines

FIGURE 4 PRECIPTT A TTC-IN CTTR-RE’C?‘lfi~lc

xing or Closed Mines

12. Giaque Lake 13. Con, Giant 14. Pine Point

armer Summers

.

312\26663-S\FIG-4 ,

NOiECOL, DAMES & MOORE,INC.

National Atlas of Canada (1974)

l Significant Producing or Closed Mines

1. Whitehorse Copper 10. Lupin 2. Mt. Nansen ii. Salmita 3. Keno Hill 12. Giaque Lake 4. Faro 13. Con, Giant 5. Ketza River 14. Pine Point 6. Sa Dena Hes 15. Rankin 7. Cantung 16. Cullaton Lake 8. Port Radium 17. Polaris 9. Terra Mines 18. Nanisivik

FIGURE 6 PROXIMITY to WATER BODIES

Nationtil Atlas of Canada (1974) .

- 12\26663-S\FIG-6 ~NoREc~I;,DAME~ 8f MOORE,INC.

l Significant Producing or Closed Mines 1. Whitehorse Copper 10. Lupin 2. Mt. Nansen il.. Salmita

3. Keno Hill 12. Giaque Lake

4. Faro 13. Con, Giant 5. Ketza River 14. Pine Point 6. Sa Dena Hes 15. Rankin 7. Cantung 16. Cullaton Lake 8. Port Radium 17. Polaris

FIGURE 5 EVAPORATION/PRECIPITATIO~

RAT.ANCE STJR-REGTONS

9. Terra Mines

/ / y --\.,t-2. \

k? 2P~~~~PI~AT10b4b.

) 04 EXCEEDS 1 Rs!T

01 i 5, ye l ’ c., . -A.-. . “A,,, EXCE,-DS

PRECIPITATION $:. ç \ i

12\26663-3\FIG-5

Based on Average Annual Precipitation and Evaporation . 1

hW&ECOL, DAMES % MOORE,INC.

-.- ! 4 ‘1

r l Significant Producing or Closed Mines

1. Whitehorse Copper 10. Lupin 2. Mt. Nansen Ii. Salmita 3. Keno Hill 12. Giaque Lake

4. Faro 13.

5. Ketza River 14. Pine Point 6. Sa Dena Hes 15. Rankin 7. Cantung 16. Cullaton Lake 8. Port Radium 17.

Con, Giant ;I= Polaris

9. Terra Mines 18. Nanisivik

FIGURE '7 MAJOR PARKS &

\ IIIL~LIFE PROTECTED AREAS 1 wrt T

Erydronment Canada (1982) I . I 312\26663-3\FIG-7

NORECOL, DAMES & MOORE,INC.

r

l Signiflcant Producing or Closed Mines FIGURE 8 1. Whitehorse Copper 10. 2. Mt. Nansen

Lupin Ii. Salmita

HIGHER PRIORITY SUB-REGIONS

3. Keno Hill 4. Faro 5. Ketza River 6. Sa Dena Hes 7. Cantung 8. Port Radium 9. Terra Mines

12. Giaque Lake TO TABLE 2 FOR EXPLANATION OF LABELS)

13. Con, Giant 14. Pine Point 15. Rankin

1 \

TINTINA I FAULT

312\26663-S\FIG-8

Geological Survey of Canada, 197: , .”

NORECOL, DAMES & MOORE, INC.

3.11. SUMMARY OF GAPS IN CURRENT KNOWLEDGE

Grant Feasby MEND Secretariat

SUMMARY OF GAPS IN CURRENTKNOWLEDGE

1. Oxidation rates of S2- 1.1. Relatively undefined at low temperature

(6 OC + < -2 “C)

2. Competing Factors in Cold Climates - for example: 2.1. 2.2.

2.3.

2.4.

Heat generation during sulphide oxidation vs freezing Increased oxygen solubility vs decreased reaction rates at low temperatures Observed reaction rates higher at low temperatures than ambient temperature (e.g. CU in Windy Craggy test cells) Biotic oxidation - bacteria adapting at low temperature vs biotic oxidation rate at low temperature

2.5. Electrochemical oxidation

3. Natural Analogues - What are they telling us?

4. Test Methods 4.1. Are chemical prediction tests performed at ambient

temperature (25 “C) relevant for northern climates? 4.2. Are chemical models using oxidation rates

‘calibrated’ to ambient temperature applicable to northern climates?

5. Waste Rock Dumps 5.1. Hydrogeology of waste rock dumps still a large

unknown 5.2. Thermal effects in waste rock dumps at low

temperatures not well defïned 5.2.1. Freezing mechanisms

6. Field Experience 6.1. Tailings and waste rock in northern climates limited

compared to more ‘southern’ areas (i.e. non- permafrost zones)

7. ARD, Alkaline drainage, Metal Fluxes 7.1. Data, field experience for northern climates needed

8. Treatment for remote, cold sites - lime treatment the only option?

9. Freezing Point Depression due to Process Chemicals 9.1. 1s this a Sign&ant effect?

10. Economie Insulating Cover Designs 10.1. With lack of caver materials in north and no

‘proven’ designs, cari a protocol for covers in the north be designed with the above in mind?