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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
Holt McDermott Holt McDermott MineMine
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
Holt McDermott Holt McDermott MineMine
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 McDermott Holt McDermott MineMine
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
Holt McDermott Holt McDermott MineMine
Cyanide…
+96% Degrades in tailings pond
Control…reducing consumption and controlling pH
Contingency….
SO2 air, peroxide, natural acidity
Holt McDermott Holt McDermott MineMine
Copper…
Complexed with cyanide, once dissociated Copper precipitates
Control…timely transfer
Contingency….
Lime, ferric sulphate, edta
Holt McDermott Holt McDermott MineMine
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
Holt McDermott Holt McDermott MineMine
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
Holt McDermott Holt McDermott MineMine
•Planning for closure