Advances in Gold Ore Processing

Cover......Page 2
Advances in Gold Ore Processing......Page 4
Contributors......Page 6
Table of Contents......Page 10
Preface......Page 14
Acknowledgements......Page 18
List of Acronyms......Page 20
List of Mineral Formulae......Page 24
Gold in Ancient Egypt......Page 26
Early Gold-Mining Centers......Page 27
Gold and Alchemy......Page 29
Uses of Gold......Page 30
Gilding......Page 31
Gilding of glass and porcelain......Page 33
Gold in the glass industry......Page 34
Gold panning......Page 35
Amalgamation......Page 36
Cyanidation......Page 38
Some recent trends in gold ore processing......Page 42
Gold Standards and Assaying......Page 43
Gold in Currency......Page 44
Banks......Page 45
Suggested Reading......Page 47
Sampling Basics......Page 52
Overall precision......Page 53
Preparation error......Page 54
Weighting and periodic quality fluctuation errors......Page 55
Percussion Hole Sampling......Page 56
Blast-Hole Sampling......Page 58
Plant Sampling......Page 60
Sampling from holding tanks and vessels......Page 65
Conclusions......Page 67
References......Page 68
Mineralogical investigation of gold ores......Page 70
Solid-solution gold......Page 71
Colloidal gold......Page 75
Surface gold......Page 78
Gravity concentration......Page 79
Floatability of gold minerals and carriers......Page 80
Size and shape of gold grains......Page 81
Silver content of native gold......Page 82
Activators and depressants......Page 84
Composition of gold mineral......Page 85
Cyanidation in leach tanks......Page 88
Heap leaching......Page 92
Other lixiviants......Page 93
Process mineralogy of gold from autoclave-CIL circuits......Page 94
Process mineralogy of gold from roaster-CIL circuits......Page 95
Process mineralogy of gold from bio-oxidized leach circuits......Page 100
Response to ultrafine grinding CIL......Page 102
Methodology for Studying Gold Minerals......Page 104
Instrumental Analysis for Gold......Page 107
Concluding Remarks......Page 110
References......Page 112
Introduction......Page 122
Overview......Page 123
Throughput......Page 125
Overview......Page 126
Treatment of high-silver ores......Page 127
Treatment of high-copper ores......Page 128
Oxygen-consuming ores......Page 130
Issues associated with mercury......Page 131
Refractory Process Selection......Page 132
Gold mineralogy......Page 134
Arsenic content......Page 135
Gangue mineralogy......Page 136
Ore variability......Page 137
Incremental gold recovery......Page 138
Site-specific environmental considerations......Page 139
Power costs......Page 140
Project life......Page 141
Discussion......Page 142
References......Page 143
Background......Page 146
Mineralogical analysis......Page 147
Gravity concentration......Page 149
Falcon and Knelson concentrators......Page 150
Cyanide leaching......Page 151
Recovery from solution......Page 152
Flotation......Page 153
Refractory gold ores......Page 154
References......Page 155
Introduction......Page 158
Benefits of Simulation......Page 159
Classification of Simulation Models......Page 161
Steady-State Continuous Simulation......Page 162
Comminution and size separation......Page 163
Recovery of gold from ore......Page 165
Dynamic Continuous Simulation......Page 166
Computational Fluid Dynamics......Page 168
The Future of Process Simulation......Page 169
General Site Issues......Page 172
Operating schedule......Page 174
Ore competence......Page 176
Requirements for blending and surge capacity......Page 177
Environment......Page 178
Single or twin-stage......Page 179
Ore material handling properties......Page 180
Power balancing......Page 181
Ball charging......Page 182
Gravity Concentration......Page 183
Product destination......Page 184
Security......Page 185
Slurry density and viscosity......Page 186
Requirement for leach feed thickener......Page 187
CIP or CIL......Page 188
Carbon movement......Page 189
Cyanide Detoxification and Tailings Disposal......Page 190
Tailings pumping......Page 191
Type of elution circuit......Page 192
Column location......Page 193
Complexity of gold room operations......Page 194
Residence time......Page 195
Wear and corrosion......Page 196
Bio-oxidation......Page 197
Pressure oxidation......Page 198
Reagents......Page 199
Water......Page 200
Special Issues for Large Facilities......Page 201
Pitfalls in Feasibility Design......Page 202
Introduction......Page 207
An Overview......Page 208
Contracting strategy......Page 209
EPC contracts......Page 210
Project complexity......Page 211
The planning process......Page 212
Roles and responsibilities in plant commissioning......Page 213
Safety considerations......Page 217
Pre-Commissioning......Page 218
Testing sequence......Page 219
Systems checks......Page 220
Personnel selection......Page 221
Water commissioning......Page 222
Operations and maintenance training......Page 223
Contractor warranties......Page 224
Process test completion......Page 225
Post-Commissioning Optimization......Page 226
Definitions......Page 227
References......Page 228
Background to the Code......Page 231
Code Development and Administration......Page 232
Case Study – Operating Site Compliance Strategy......Page 234
Verification and Certification......Page 244
Practical Advice for Audit Teams......Page 245
References......Page 247
Process control......Page 250
Slurry flowrate......Page 251
Particle size of milled product......Page 252
Actuators......Page 253
Hierarchy......Page 254
Advanced Control and Optimization......Page 255
Crusher plant control......Page 256
Mill circuit control......Page 257
Flotation......Page 258
References......Page 261
Process Closure and Clean-Up......Page 263
Relocation and Sale – Owner’s Perspectives......Page 264
Relocation and Sale – The Marketing Manager’s Perspectives......Page 267
Consideration of Heritage Values Prior to Closure and Decommissioning......Page 268
Infrastructure Removal and Site Decommissioning......Page 270
Closure Plant Sites – Contamination and Risk......Page 274
Final Land Use and Rehabilitation – Plant Sites......Page 276
References......Page 277
Standards and Closure Criteria......Page 282
Closure Preparation, Provisioning and Planning......Page 284
Stakeholder Engagement and Acceptance of Plans......Page 287
Decommission Planning, Rehabilitation, and Closure......Page 289
Water management......Page 291
Vegetative stabilization......Page 292
Variability......Page 293
Post-Closure Management, Monitoring and Relinquishment......Page 294
Conclusions......Page 297
References......Page 298
Introduction......Page 302
Circuit Design Issues......Page 303
Drilling and Blasting......Page 305
Primary Crushing and Stockpile Management......Page 308
SAG Mill Configuration and Operation......Page 309
Lifter development......Page 310
Pulp discharge......Page 311
Grinding media size......Page 313
Mill relines......Page 314
Pebble crushing......Page 315
Ball-Mill Circuit Operation......Page 319
Gold Recovery in Comminution Circuits......Page 320
Process Control......Page 322
Alternate Grinding Technologies......Page 323
References......Page 324
Introduction......Page 329
Economics......Page 331
Existing practice......Page 333
Optimum yield and recovery......Page 334
Testwork......Page 335
Beaconsfield gold mine......Page 336
St. Ives gold mine......Page 337
Existing practice......Page 338
Testwork......Page 341
Unit and flowsheet selection based on test results......Page 342
Modelling for unit selection, circuit design and optimization......Page 343
Table-based recovery......Page 345
Intensive cyanidation......Page 348
The batch inline leach reactor......Page 349
Acacia reactor......Page 350
Continuous inline leach reactor......Page 351
Measuring Metallurgical Performance......Page 352
References......Page 354
Background......Page 358
General aspects of gold flotation......Page 359
Surface characteristics of pure gold......Page 360
Flotation collectors for gold and gold carriers......Page 361
Frothers in Gold Flotation......Page 364
Metal salts......Page 365
Sulfidization......Page 367
Selective depression of sulfide minerals......Page 368
Depression of sulfide minerals with cyanide......Page 369
Flotation of telluride minerals......Page 370
Flotation of aurostibite, stibnite, and maldonite......Page 371
Eh of the flotation pulp......Page 372
Flotation gases and the impact of oxidation on flotation......Page 374
Modification of pH for flotation......Page 375
Flotation kinetics......Page 376
Slime coatings and floatable non-sulfide gangue......Page 377
Natural metal and organic coatings on gold......Page 379
Flotation Practice......Page 380
Arsenopyrite, pyrrhotite and pyrite ores......Page 381
Gold ores containing telluride minerals......Page 382
Pyritic gold ores......Page 383
References......Page 384
Pressure oxidation overview......Page 395
Thermodynamic considerations......Page 396
Kinetic considerations......Page 398
Environmental considerations......Page 400
Pressure hydrometallurgy history......Page 401
Gold Pressure Oxidation......Page 404
Geology and mining......Page 405
Autoclave circuit......Page 406
Geology and mining......Page 408
Acid chemistry......Page 410
Alkaline chemistry......Page 411
Operating cost......Page 412
Acidic Pressure Oxidation – Concentrate......Page 413
References......Page 417
Bacterial oxidation of refractory gold concentrates......Page 420
Introduction and Background......Page 421
Current Bacterial-Oxidation Plant Design and Practice......Page 424
Agitation, aeration and reactors......Page 427
Cyanide consumption of bacterially-oxidized residue......Page 429
Reasons for high cyanide consumption......Page 431
Prevention and cure of polysulfide formation......Page 433
Polysulfide process prevention – influence of bacterial-oxidation residence time......Page 434
Polysulfide process prevention – influence of feed particle size......Page 437
Polysulfide process prevention – bacterial-oxidation intermediate liquor removal......Page 438
Polysulfide process prevention – effect of solid/liquid separation after bacterial oxidation......Page 440
Brief Comparison of Bacterial Oxidation with Process Alternatives......Page 443
Conclusions......Page 445
Recommendations for Future Areas of Investigation......Page 446
Liquor stripping to enable operation at a higher pulp density......Page 447
References......Page 448
Roasting developments – especially oxygenated roasting......Page 452
Rabble Roasters......Page 454
Fluidized-Bed Roasters......Page 455
Circulating Fluidized-Bed (CFB) Roasters......Page 457
Oxygenated Roasters......Page 459
Introduction......Page 460
Roaster chemistry......Page 462
Dry grinding......Page 465
Roaster operation......Page 466
Process design basis – roaster......Page 469
Process design basis – roaster off-gas cleaning......Page 474
References......Page 479
History of Gold-Ore Circulating Fluid-Bed Roasting Technology......Page 482
Theoretical Background of Roasting......Page 483
The ’expanded’ fluidized bed......Page 484
Testing and plant design......Page 485
Scale-up approach for circulating fluidized-bed systems......Page 486
Alumina calcination......Page 487
Charring of high volatile-matter (VM)-containing coals with pre-reduction......Page 488
Roasting of refractory gold - ores......Page 489
Kalgoorlie Consolidated Gold mines – Gidji, Western Australia......Page 492
Slurry-feed system......Page 493
Roasting......Page 494
Gas cleaning operation......Page 495
Ore pre-heating operation......Page 496
Roasting operation......Page 497
Gas-cleaning operation......Page 498
Roasting operation......Page 499
Further Reading......Page 501
Introduction......Page 505
Why select heap leaching as the processing method?......Page 507
Lack of sufficient reserves......Page 508
Type of ore......Page 509
Saprolites/laterites......Page 510
Climate extremes......Page 511
Recovery delay in multiple lift heaps......Page 512
Laboratory testing and control......Page 513
Design for temperature extremes......Page 514
Water balance......Page 515
Solution application equipment......Page 516
Valley fill heap leach......Page 517
Mining, ore preparation and stacking......Page 518
Truck stacking......Page 520
Recovery of gold and silver from heap-leach solutions......Page 521
Design considerations for reclamation and closure......Page 523
Conclusions......Page 524
Acknowledgements......Page 525
Further Reading......Page 526
Introduction......Page 528
Chemistry and electrochemistry......Page 529
Reaction with sulfide minerals......Page 531
Control of cyanide......Page 535
Oxygen......Page 537
Lead nitrate......Page 539
Low-sulfide ore......Page 541
Gold ore with pyrite and arsenopyrite......Page 543
Gold ore with pyrrhotite......Page 545
References......Page 546
Introduction......Page 550
Stability of alternative lixiviants and gold complexes......Page 552
Thiosulfate Leaching......Page 553
Thiosulfate – optimum conditions for leaching......Page 554
Thiourea – process conditions......Page 555
Thiourea – stabilizers......Page 556
Thiourea – applications......Page 557
Halide Leaching......Page 558
Halides – process conditions......Page 559
Bromine......Page 560
Iodine......Page 561
Halides – current status......Page 562
Oxidative Chloride Leach Processes......Page 563
Oxidative chloride leach – process conditions......Page 564
Oxidative chloride leach – current status......Page 565
Sulfide/bisulfide/sulfite leaching – process conditions......Page 566
Nitrogen species catalysed pressure leaching process......Page 568
Sulfide/bisulfide/sulfite leaching – current status......Page 569
Ammonia – process conditions......Page 570
Bacterial and natural acid – conditions......Page 571
Thiocyanate – conditions......Page 573
Thiocyanate – current status......Page 574
Economic Evaluation......Page 575
Environmental Concerns......Page 578
Conclusions......Page 580
Acknowledgments......Page 581
References......Page 582
Introduction......Page 590
Mechanism of gold leaching......Page 592
Kinetics of gold leaching......Page 595
Decomposition of thiosulfate and polythionates......Page 596
Background and recent studies......Page 599
Factors affecting gold recovery and optimum reagent composition......Page 601
Alternative thiosulfate systems......Page 602
Summary and Conclusions......Page 603
References......Page 605
Early history of carbon use in gold recovery......Page 611
The modern era of CIP......Page 612
Kinetic activity......Page 613
Wet-attrition resistance......Page 616
Moisture content......Page 617
Modelling Carbon-in-Pulp Circuits......Page 618
Stange model......Page 619
Number of adsorption stages......Page 620
Pump cells and carousel circuits......Page 622
Carbon residence time......Page 624
Effect of carbon activity on soluble gold loss and carbon inventory......Page 625
Effect of carbon distribution on soluble gold loss......Page 626
Carbon usage rate......Page 627
Target gold loading on carbon......Page 629
Gold-loading distribution......Page 630
Carbon transfer......Page 631
References......Page 632
Chemistry......Page 638
History......Page 640
High mercury content......Page 641
Basic flowsheet......Page 642
De-aeration......Page 644
Precipitate filtration......Page 645
Design criteria......Page 646
South America......Page 648
Advances......Page 649
References......Page 650
Introduction......Page 652
Solution Chemistry of Cyanided Gold Pulps......Page 653
Development of Gold-Selective Resins......Page 654
Strong-base resins......Page 655
Weak-base resins......Page 656
Elution of minix strong-base resin......Page 657
Elution of AM-2B resin......Page 658
Elution of AuRIXreg resin......Page 659
Elution of conventional strong-base resins (A161 L, A161RIP, Vitrokele 912)......Page 660
Mini-column loading tests......Page 662
Equilibrium isotherm......Page 663
Kinetics......Page 665
Simulation of an adsorption circuit......Page 667
Resin strength and durability......Page 668
Relative Cost Comparison of RIP vs. CIP......Page 671
Recovery of Gold from Preg-Robbing Ores......Page 673
Minix......Page 675
AuRIXreg......Page 676
Penjom Gold Mine, Malaysia......Page 678
Barbrook Gold Mine, South Africa......Page 680
References......Page 681
Background......Page 686
Historical Developments......Page 688
Cell types in use in Australia......Page 689
Cells for pressurized elution circuits......Page 690
Wound single-layer wrapped cathodes......Page 691
Woven stainless-steel cathodes - plate and replate cells......Page 692
Pressure-jetting bullion-sludge removal......Page 693
Pressurized electrowinning cells......Page 694
Direct electrowinning from biologically oxidized filtered leach solutions......Page 695
Current requirements......Page 696
Number of cathodes required......Page 697
Electrical connections (resistivity, material selection and fire)......Page 698
Automatic current-control rectifiers......Page 699
References......Page 700
Introduction......Page 702
Evaluation......Page 705
The High-Speed Silver-Electrolysis Plant Operation......Page 707
Gold Electrolysis......Page 710
Rand Refinery Smelter Operations......Page 715
Small-Bar Plant......Page 717
References......Page 718
Introduction......Page 721
Cyanide Management Plan......Page 722
Analysis of Cyanide......Page 723
Biological Cyanide Destruction Processes......Page 724
Alkaline chlorination process......Page 729
Sulfur dioxide and air process......Page 731
Copper-catalysed hydrogen peroxide process......Page 732
Caro’s acid process......Page 733
Iron-cyanide precipitation......Page 734
Activated carbon polishing......Page 736
Other cyanide-treatment processes......Page 737
Natural Cyanide Attenuation......Page 738
Thiocyanate treatment......Page 740
Cyanate treatment......Page 741
Ammonia treatment......Page 742
Nitrate treatment......Page 744
Effluent Standards......Page 745
Summary......Page 747
References......Page 748
Cyanide recovery......Page 752
Introduction......Page 753
Theoretical Background......Page 754
Practical Considerations......Page 756
Direct recovery by the SART process......Page 758
Direct recovery by the AVR process......Page 761
Indirect recovery with preconcentration by ion-exchange resins......Page 763
Cyanide recovery by RIP using zinc complexation (zinc cyanide process)......Page 764
The AuGMENT process......Page 768
The Hannah process......Page 771
Environmental, Social, Health and Safety Benefits of Cyanide Recycling......Page 772
References......Page 774
Evolution of Tailings Management......Page 778
Public perceptions and politics......Page 780
Tailings Characterization......Page 781
Particle size distribution......Page 782
Permeability......Page 783
Shear strength......Page 784
Piezocone investigations......Page 785
Kinetic testing......Page 786
Risk-Based Design......Page 787
Recent Major Advances......Page 789
Water reduction......Page 790
Backfill......Page 791
Lining of tailings storage facilities......Page 792
Management of acid mine drainage......Page 793
Safety......Page 794
Aesthetic acceptability......Page 795
Paste......Page 796
Co-disposal of mine wastes......Page 797
High-sulfur management......Page 798
References......Page 799
Introduction......Page 802
Scouting......Page 803
Sampling and Metallurgical Testwork......Page 804
Sample preparation......Page 805
Metallurgical testwork......Page 806
Flowsheet development......Page 807
Tonnage and grade calculation......Page 808
General observations......Page 809
Infrastructure requirements......Page 810
Operating costs......Page 811
Reclamation methods overview......Page 812
Slime reclamation by hydraulic re-mining......Page 813
Reclamation technique......Page 815
Monitor guns......Page 817
Screening......Page 818
Pump stations......Page 819
Pipelines......Page 820
Water balance......Page 821
Reclamation guidelines......Page 822
Mechanical reclamation of sand......Page 823
Slime treatment with no pyrite recovery......Page 824
Slime treatment with pyrite recovery......Page 827
Environmental Rehabilitation......Page 829
Process Flowsheets......Page 830
Further Reading......Page 832
Chemistry of Copper Cyanides......Page 838
Copper– cyanide complexes......Page 840
Solubility of copper minerals in cyanide solutions......Page 842
Reactions of copper minerals in cyanide solutions......Page 843
Preg-robbing of gold onto copper and copper minerals......Page 844
Effect of copper– cyanide complexes on the gold cyanidation process......Page 845
Effect of sulfides with copper on the gold cyanidation process......Page 846
Gold Recovery......Page 847
Carbon-in-pulp and Carbon-in-leach process......Page 849
Processes for Treating High-Copper Gold Ores......Page 850
Use of ammonia for minimization of the effect of copper......Page 851
Plant experience using ammonia......Page 854
Sulfide-precipitation processes......Page 857
Cutech process......Page 858
Sceresini process......Page 859
CyanisorbTM process......Page 861
VitrokeleTM......Page 862
Augment process......Page 863
Ion-exchange technologies –- solvents......Page 864
Electrowinning......Page 867
Thiosulfate leaching......Page 868
References......Page 869
Introduction......Page 874
Background – Sulfide Leaching......Page 878
Copper–Gold Concentrate Treatment Processes......Page 881
Total pressure-oxidation process......Page 883
BIOCOPTM process......Page 886
Outokumpu HydrocopperTM process......Page 887
Anglo American Corporation/University of British Columbia copper process......Page 889
PLATSOL® process......Page 891
Conclusions......Page 892
References......Page 894
Fundamentals......Page 898
Slurry processes......Page 903
Gold recovery on carbon......Page 904
Gold recovery by Merrill– Crowe......Page 906
Indicative Plant Design Criteria......Page 907
References......Page 908
Introduction......Page 910
Recovery of Gold in Copper Smelters......Page 911
The Outokumpu Pori refinery......Page 912
Phelps Dodge El Paso refinery......Page 913
Recovery of Gold as a By-Product from Nickel Sulfide Ores......Page 915
Inco......Page 917
Falconbridge......Page 921
Norilsk......Page 922
Recovery of Gold in Zinc Smelters......Page 925
Roast-leach-electrowinning......Page 926
Sherritt Gordon zinc pressure-leaching (ZPL)......Page 927
Smelting processes......Page 929
Hydrometallurgy for lead concentrates......Page 932
Recovery of Gold from Cobalt Concentrates......Page 934
Direct Leaching of Gold and PGMs from Ores or Concentrates......Page 935
The North American palladium process......Page 937
The PLATSOLTM process......Page 938
References......Page 940
1. Primary Extraction Circuits......Page 946
2. Gold Extraction from Secondary Sources......Page 948
Gold– copper alloys......Page 950
Low-grade Cu– Au–PGM......Page 951
Traditional methods......Page 952
Modern low-grade circuits......Page 953
Hydrometallurgical Gold Processes in Precious Metal Refineries......Page 955
Dissolution of concentrates and alloys......Page 956
Selective reduction of gold in PGM solutions......Page 957
Selective solvent extraction of gold from PGM solutions......Page 959
Gold solvent extraction with dibutyl carbitol......Page 961
Gold solvent extraction with MIBK......Page 962
Ion exchange......Page 963
References......Page 964
III.2 Refractory Ores......Page 968
Introduction......Page 969
Sansu Project, Ashanti Goldfields Corporation (Ghana)......Page 970
Kanowna Belle Project (Western Australia)......Page 975
Macraes Gold Project (New Zealand)......Page 980
References......Page 983
Introduction......Page 986
Chemical characteristics......Page 991
Adsorption phenomena......Page 993
Treatment of Carbonaceous Ore......Page 998
Activated carbon-in-leach (CIL) and resin-in-leach (RIL)......Page 999
Blinding or blanking......Page 1000
Roasting......Page 1001
Chlorination......Page 1002
Pressure oxidation......Page 1003
Nitric acid treatment......Page 1004
Thiosulfate leaching......Page 1005
Non-Carbonaceous Preg-Robbing......Page 1007
Examples of Plant Practice......Page 1008
Practical Ore Characterization......Page 1010
References......Page 1012
Tellurium-bearing ores and materials......Page 1022
Assaying......Page 1023
Cripple Creek......Page 1024
Kalgoorlie......Page 1025
Kirkland Lake......Page 1026
Fiji......Page 1027
Cyanide leaching – testwork results......Page 1028
Cyanide leaching – theoretical considerations......Page 1030
Other oxidative processes......Page 1031
References......Page 1032
Fundamentals......Page 1034
Commercial Operations......Page 1036
Consolidated Murchison......Page 1037
New Plant Design......Page 1038
References......Page 1039
Summary of Gold Plants and Processes......Page 1043
Conclusions......Page 1044
Subject Index......Page 1064