Cyanide Management by SARTby

Janene Barter, Greg Lane - GRD Minproc LimitedRobert Dunne, Dean Mitchell, Roger Kelson - Newcrest Mining Limited

Chuong Trang - Lakefield Research LimitedDavid Dreisinger - University of British Columbia

NEWCREST MINING LIMITED

GRD Minproc Limited

Newcrest Mining Limited

This PresentationThis Presentation

Testwork and Design

Process SART Selection

Telfer

GRD Minproc Limited

Newcrest Mining Limited

Telfer LocationTelfer Location•Darwin

•Telfer

Process Telfer SART Selection

Testwork andDesign

GRD Minproc Limited

Newcrest Mining Limited

Copper ore body

Copper gold ore body

1977 Merrill Crowe Circuit

1986 Conventional CIL

Telfer Ore ProcessingTelfer Ore Processing

Testwork andDesign

Process Telfer SART Selection

GRD Minproc Limited

Newcrest Mining Limited

Sulfide ore

Flotation Flotationtails

Pyrite concentrate

Copper sulfide concentrate

To Market

Oxide ores

CILCIL tailings

Low grade oxide ores Elution

Telfer Ore ProcessingTelfer Ore Processing

Testwork andDesign

Process Telfer SART Selection

Heap Leach

GRD Minproc Limited

Newcrest Mining Limited

Telfer Ore ProcessingTelfer Ore Processing

Telfer Treatment ScheduleCIL Feed Rate and Cyanide Soluble Copper Grades

Year CIL Feedt/h

CIL Feed CNSolCu Gradeg/t

98/99 235 128

99/00 239 146

00/01 202 1418

Process Telfer SART Selection

Testwork andDesign

GRD Minproc Limited

Newcrest Mining Limited

Bench scale process• membrane technologies, solvent extraction, too risky,

operating and capital costs too high.

Ion flotation

• trialed twice

Cyanide destruction

• high operating cost, no cyanide or copper recovered

Cyanide recovery

• ammonia cyanide recovery, AVR, high operating costs, no copper recovered

Testwork andDesign

ProcessTelfer SART Selection

Telfer Testwork andDesign

Cyanide Management ProcessesCyanide Management Processes

GRD Minproc Limited

Newcrest Mining Limited

Cyanide and copper recovery• CRP and Acid and copper precipitation

– unmarketable copper products

• SART

– Merrill Crowe CCD, flotation plant, heap leach

– copper and cyanide recovered

– Cu2S easily marketed

Cyanide Management ProcessesCyanide Management Processes

Testwork andDesign

ProcessTelfer SART Selection

Telfer Testwork andDesign

GRD Minproc Limited

Newcrest Mining Limited Testwork andDesign

Process Telfer SART SelectionTelfer

SART Process at TelferSART Process at Telfer

CCD

SART

CIL Tails

Wash Water

Underflow (50 ppm WAD CN)

O/FOxide mill

Heap leach

Copper sulfide to existing flotation thickener

Cyanide in solution

GRD Minproc Limited

Newcrest Mining Limited

SART ProcessSART Process

2Na3Cu(CN)4 + 3.5 H2SO4 +NaSH Cu2S (s) + 3.5 Na2SO4 + 8 HCN

2HCN + Ca(OH)2 Ca(CN)2 + 2 H2O

SART Thickener

Underflow (Copper sulfide)

SART Reactor

Overflow (cyanide)

Neutralisation (cyanide)

Testwork andDesign

Process Telfer SART SelectionTelfer

GRD Minproc Limited

Newcrest Mining Limited

Reagent consumptions

Copper and cyanide recoveries

Expected performance• 5.4 t/d copper

• 2.5 t/d cyanide

• Operating cost down by 35%

Pilot plant testwork

Bench Scale TestworkBench Scale Testwork

Testwork andDesign

Process Telfer SART SelectionTelfer

GRD Minproc Limited

Newcrest Mining Limited

pH versus Copper and Cyanide Recovery

92

93

94

95

96

97

98

99

4 4.4 4.7 5.1

pH

Cop

per

reco

very

(%)

84

86

88

90

92

94

963.92 3.91 3.82 3.4

Acid Consumption (kg/Copper)

Cya

nide

Rec

over

y (%

)

Copper recoveryCyanide recovery

Telfer Testwork andDesign

ProcessTelfer SART Process

TelferTelfer

Pilot PlantPilot Plant

GRD Minproc Limited

Newcrest Mining Limited

Copper and Cyanide Recovery Versus NaSH Addition

90

91

92

93

94

95

93 99 112

Stoich. NaSH %

Cop

per

reco

very

(%

)

90

91

92

93

94

95

Cya

nide

rec

over

y (%

)

Copper recoveryCyanide recovery

Pilot PlantPilot Plant

Telfer Testwork andDesign

ProcessTelfer SART Process

TelferTelfer

GRD Minproc Limited

Newcrest Mining Limited

Copper Recovery Versus Residence time

94

95

96

97

98

5 10 15 20 25 30

Residence time (minutes)

Rec

over

y (%

)

Pilot PlantPilot Plant

Telfer Testwork andDesign

ProcessTelfer SART Process

TelferTelfer

GRD Minproc Limited

Newcrest Mining Limited

Pilot PlantPilot Plant

SART reactor agitation• Different agitators trialed, no effect

Copper sulfide thickening• High underflow density:

– minimise cyanide losses– limits copper dissolution– sulfide suppression

Neutralisation• Lime consumption 3.6 kg/t• Stand-by neutralisation tank, gypsum thickener

Telfer Testwork andDesign

ProcessTelfer SART Process

TelferTelfer

GRD Minproc Limited

Newcrest Mining Limited

Other ConsiderationsOther ConsiderationsLocation and control• Reduce operator interaction

• NaSH dosage:

– hydrogen sulfide gas and thiocyanate – copper is recirculated, consumes reagents– copper analyser

Water balance• Excess water to heap leach

• Operations without heap leach

Telfer Testwork andDesign

ProcessTelfer SART Process

TelferTelfer

GRD Minproc Limited

Newcrest Mining Limited

SummarySummary

Simple and robust

Cyanide and copper recovered

Existing CCD thickeners and flotation plant

Excess water used in heap leach

Adaptable to other operations

GRD Minproc Limited

Newcrest Mining Limited

Plant OperationPlant OperationDesign Actual

Sulfuric acid t/t Copper 3.6 2.80Lime t/t Copper 3.6 2.03NaSH usage t/t Copper 0.44 0.77

Operating pH 4-5 5.1Copper feed grade ppm 537 606WAD cyanide feed grade ppm 855 794Copper recovery % 95 87-99WAD CN to free cyanide % 93 72-93