water management and the use of natural degradation in a...

Water Management and the Use ofWater Management and the Use ofNatural Degradation in a Gold Mine Natural Degradation in a Gold Mine

Tailings Management FacilityTailings Management Facility

Holt McDermott Mine

BARRICK GOLD CORPORATIONBARRICK GOLD CORPORATION

Sudbury 2003 Conference

R.L. Martel, CET, CCEP (Barrick)K.A. Bocking, P.Eng (Golder Association Ltd.)

HoltHolt--McDermott MineMcDermott Mine

nn 215 employees 215 employees nn From Ontario and From Ontario and

QuebecQuebecnn Over 700 Over 700

Kilometers North Kilometers North of Torontoof Toronto

Past and PresentPast and Present

1940 1987 to present

Located on the Legendary “ Porcupine to DestorBreak” which hosted dozens of gold mines

Both Holt and Holloway ores are hosted in volcanic rocks

Underground Mining

Milling using CIL

Tailings Management and effluent treatment

using Natural Degradation

Holt McDermott Holt McDermott MineMine

Beached Tailings planned as closure option until 1998Beached Tailings planned as closure option until 1998

Arsenic and PAG tailings calls for flooded closure optionArsenic and PAG tailings calls for flooded closure option

Renegotiate and finalized contract AgreementRenegotiate and finalized contract Agreement

CEAA authorization of project expansionCEAA authorization of project expansion

Tailings Pond expansion 2000 Tailings Pond expansion 2000 -- 20012001

In total… 4 ponds contained by 18 dams In total… 4 ponds contained by 18 dams

Changes at Tailings Management Facility

Alternatives and evaluationAlternatives and evaluation

• Inter-agency consultation

• Project alternatives

1. Continue operations as they are

2. Raise the existing Dams

3. Develop a “New” polishing pond

4. Provide chemical Treatment of the effluent• Performance objectives

1. Economics

2. Minimizing environmental impact

3. Ease to rehabilitate

TAILINGS MANAGEMENT FACILITY EXPANSION TAILINGS MANAGEMENT FACILITY EXPANSION 2000 2000 –– 20012001

• Reason: To provide tailings storage capacity for longer term milling…

• Cost: $ 3.5 M

• Schedule: 1.5 years total

1 year constructing new polishing pond

• Main Items: 5 dams built, 1 raised, Spillway

Long term erosion protection

Decant tower

Ferric Sulfate system


TAILINGS MANAGEMENT SYSTEM EXPANSION 2000 – 2001“Issues considered during the permitting process”

• Alternatives ( Chemical versus Natural )

• Vary wide range of discharge ( 1000 - 100,000 m3/d)

• Period of discharge to 9 month’s per year

• Large variety of water discharge scenario’s

• Possibility of chemical addition following testwork


FLEXIBILITY….

Inputs Inputs :: Fresh Water 20%Fresh Water 20%Holt U/G waterHolt U/G water 19%19%Custom Mine water 4%Custom Mine water 4%Precipitation 57%Precipitation 57%

RecycleRecycle: : 54%54%

Discharge:Discharge: 2.5 2.5 -- 3.0 m3/year ( 750M 3.0 m3/year ( 750M usgusg/yr )/yr )SeasonalSeasonal

TMF area:TMF area: 470 Ha470 Ha


Holt Tailings Management FacilityHolt Tailings Management Facility

Primary

Transitional and

contingency

South

North

Tailings DepositionTailings Deposition

Pre-Polishing

Polishing

Discharge

Polishing Ponds

Main Contaminants :

Ammonia

ArsenicCopper

Cyanide


Cyanide…

+96% Degrades in tailings pond

Control…reducing consumption and controlling pH

Contingency….

SO2 air, peroxide, natural acidity


Copper…

Complexed with cyanide, once dissociated Copper precipitates

Control…timely transfer

Contingency….

Lime, ferric sulphate, edta


Arsenic…

Independent

Control…timely transfer

Contingency….

Lime, ferric sulphate

Ammonia…

Persistent…(Cyanide hydrolysis)

No real reduction in tailings pond

Contingency….

Polishing Pond does all the work…

Polishing pond effectiveness relies on natural Phosphorus…and its biological processes

pH reduction, aeration, phosphorus addition

Framework

Continual improvement

Seeking to minimize the impact of our operations on the environment.

Having systems in place

Conform with Mac Guidelines Dam ClassificationRisk Assessments

Surveillance SystemMonitoring ProgramOperating Manual

Training

HOLT McDERMOTTMINE

Tailings Management

System

Operating, Maintenanceand Surveillance Manual

2002

Water Management Strategy

• identified 1 year of space before contingencies measures need to be implemented

Water Management Strategies and ContingenciesWater Management Strategies and ContingenciesHOLT-McDERMOTT MINE TAILINGS MANAGEMENT FACILITY

WATER MANAGEMENT STRATEGY

INTRODUCTION

In the spring of 2001, the New Polishing Pond (NPP) will be commissioned to receivedwater from the Southwest Basin ( SWB ). Discharge from the NPP is scheduled to takeplace shortly after this transfer. The Southeast Polishing Pond ( SEPP ) will alsodischarge in the fall of 2001 either to the NPP or directly to the final effluent control point( FECP ). Water from the North Basin ( NB ) will either discharge in the fall of 2001 or inthe early spring 2002 depending on water quality results. Once through this transitionalperiod, 2002 will be first full year the NPP will be in use. Section 3.2.3 of the CEAA andWastewater Permitting Support Document describes the flexibility and the intent of thefuture operations of the Tailings Management System ( TMS ).

This report provides an evaluation of water management strategy for two cases:

Case 1; a typical year, scheduled dischargeCase 2; a year, where no discharge from TMS takes place in the first year of a two yearperiod.

CASE SELECTION

Case 1 ( typical ) considers average mill tonnage, average climatic conditions andscheduled discharge volumes. Case 1 assumes a seasonal transfer from the tailingsbasin to the NPP which subsequently leads to a fall discharge, also that runoff from boththe SEPP and the NTB discharge to the environment via the Final Effluent Control Point( FECP ). The following figure and table provides an illustration and description of thewater management activities for a typical year. ( Case 1 )

No.

Description Period

1 Tailings to SWTB Annual2 SEPP To Magusi April3 Seasonal Transfer May Jun4 Seasonal Transfer Jun Jul5 Seasonal Disch. Sept,Oct, Nov

6 NPP to Magusi Sept, Oct Nov

NB

SWTB SEPP

1

3

5

NPP

2

4

6

2.0 CONTINGENCIES

Considering past operating performance, the critical contaminants that areaddressed in this submission are cyanide, copper, arsenic and ammonia. So longas these key contaminants are effectively managed, none of the othercontaminants have the potential to be of concern and contingency measure’s formore effective system operation will not be required. However, if it should turnout for any reason that any effluent contaminant is of a concern, there areseveral possible contingency measure’s that would be available for use at thesite. These measure’s are divided into two main category’s, that is, measuresused to: 1) sustain typical or historical effluent concentrations and, 2) to meetProcess Effluent Limits under Ontario Regulation 560/94 using correctivemeasure’s.

3.1 Sustainable Measures

• further extended effluent aging within the system, including paralleloperation of the NPP and the south east basin polishing pond and holdingfall discharge until spring;

• increased receiving water to effluent mixing ratio;

• use of treated water as a pH modifier;

• use of ferric sulphate;

3.2 Corrective Measures

• addition of oxidation agent ( like Hydrogen Peroxide ) to facilitate cyanidedestruction and associated heavy metal removal;

• use of chelating agents such as ethylenediaminetetraacetate (EDTA) toreduce copper toxicity;

• phosphorus introduction to the NPP ( or the SEPP ), as appropriate, toassist with

ammonium ion uptake by algae;

• pH adjustment using chemical addition;

The most important aspect of the above contingency measure’s is that, theycould be employed either in parallel, or in series as the new system has theflexibility, this flexibility will assist to achieve optimal system performance.

……Planning in advance, knowing what’s aheadPlanning in advance, knowing what’s ahead

Contingencies

Sustainable measures

• extending effluent aging

• increasing receiving water to effluent mixing ratio

• use of polished water as a pH modifier

• ferric sulphate

Correctives measures

• addition of oxidation agent (like hydrogen peroxide) to facilitate cyanide destruction

• EDTA…to reduce copper toxicity

• phosphorus introduction to polishing pond

• pH adjustment

Testing with Ferric SulphateTesting with Ferric Sulphate

1:1 5:1 10:1

Approach…

Seasonal Transfer Fall Discharge

Continuous Improvement

Natural AcidityPre – starting polishing Pond

Isolating Sludge

Water Quality Results since 1996Water Quality Results since 1996

Table 1Cu and As loading/day of disch/yr

012345678

1997 1998 1999 2000 2001 2002

kg/d

of d

isch

Copper

Arsenic

Table 2Un-ionized Ammonia and TCN

loading/day of disch/yr

00.20.40.60.8

11.21.41.6

1997

1998

1999

2000

2001

2002

kg/d

of

dis

ch Un-ionizedAmmonia

Total Cyanide

Cu As

Un-ionized

AmmoniaTotal

Cyanide1996 0.11 0.013 0.004 0.0111997 0.13 0.014 0.003 0.0171998 0.08 0.016 0.002 0.0041999 0.06 0.014 0.035 0.0062000 0.04 0.027 0.016 0.0052001 0.02 0.012 0.012 0.0032002 0.02 0.010 0.040 0.005

Average Effluent Discharge Concentration (mg/L)

Daphnia magna

20022002200120012000200019991999199819981997199719961996

0000000000001515001515001010000000

Daphnia Daphnia MagnaMagna

Rainbow Rainbow TroutTrout

Acute Toxicity Test Results % Mortality


Planning for Closure…Planning for Closure…

Long Term Erosion Protection of our Tailings Dams

( Water Cover Research )( Water Cover Research )

B

C

A

Cell #A: 1 metre water ( standard )Cell #A: 1 metre water ( standard )

Cell #B: 1 metre water + 1cm of org. Cell #B: 1 metre water + 1cm of org. substratesubstrate

Cell #C: 0.5 metres water + cattails Cell #C: 0.5 metres water + cattails

MASS AND POREWATER CHARACTERIZATION MASS AND POREWATER CHARACTERIZATION of tailings…of tailings…

WATER QUALITY IMPROVEMENTSWATER QUALITY IMPROVEMENTS““Understanding + effort = resultsUnderstanding + effort = results””

ReasonsReasons

•Accurate water balance

•Evaluation of historical data

•Evaluation of contingency measures

•Optimization of retention time and precipitate storage

•Developed water management strategies

•Pre-discharge planning

•Established contaminant loading as core value

•Operator and staff awareness training


•Planning for closure

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