COMPARISON OF SEMI‐AUTOGENOUS MILLS OPERATIONS IN ANDEAN COUNTRIES

Juan RayoTechnical Director and Founder, JRI Ingeniería S.A., jrayo@jri.cl

INTRODUCTION• Andean Countries (Argentina, Bolivia, Chile

& Peru) currently have 42 SAG mills inoperation. By the end of next decade, thetotal amount will likely be close to 100.

• JRI has been involved, direct or indirectly,with the design and/or performance of alarge portion of the SAG grinding sectionsin these countries.

• This presentation will show the maintechnical data in SAG mills, to be used forcomparison with Australian grindingperformance data.

• In addition, this presentation will include asummary of historical operational focusand SAG current trends.

SEMI‐AUTOGENOUS MILL OPERATING IN SOUTH AMERICA

CHILE Quantity PERÚ QuantityC1 Collahuasi 3 D1 Antamina 2C2 Codelco ‐ Chuquicamata 2 D2 Toromocho 1C3 Codelco ‐Ministro Hales 1 D3 Antapaccay 1C4 Esperanza 1 Cerro Corona 1C5 Escondida ‐ Los Colorados 3 Yanacocha 1C6 Escondida ‐ Laguna Seca 1 Ares 1C7 Candelaria 2 Orcopampa 1C8 Carmen de Andacollo 1 Uchucchacua 1C9 Los Pelambres 3 TOTAL 9C10 Codelco ‐Andina 1C11 Los Bronces 2 ARGENTINA QuantityC12 Confluencia 1 Alumbrera 2C13 Codelco ‐ El Teniente 2 TOTAL 2

Altonorte 1Caserones 1 BOLIVIA QuantityEl Peñón 1 San Cristobal 1El Soldado 1 Bolivar 1Mantos de Oro 1 TOTAL 2Codelco ‐ Salvador 1El Bronce Petorca 1

TOTAL 30

SAGs MAIN CHARACTERISTICS

SAGs MOTOR SIZINGInstalled Power per Mill

SAGs NOMINAL TREATMENTTreatment Rate per SAG Mill

SAGs UNIT RATESAG Throughput per Installed kW

SAGs UNIT RATEPower to Treatment Relationship

SAGs ORE SIZE DATASAG Mill Feed (F80)

SAGs ORE SIZE DATASAG intermediate product (T80)

SAGs ORE SIZE DATAFinal grinding product (P80)

SAGs ORE WORK INDEXWork index (WI)

SAGs ENERGY CONSUMPTIONSpecific energy consumption per SAG mill (SEC)

SAGs CIRCUITSN° ball mill per SAG mill

SAGs GRINDING POWERBall mill power per SAG power installed

SAGs BALL STEEL CONSUMPTIONSteel consumption

SAGs DISCHARGE CONCENTRATION

SAG discharge solid [%] 

SAGs PEBBLES GENERATIONPebbles produced per tonne feed

SAGs UTILIZATION RATEHourly operation per day

SAGs BALL CHARGEBall Charge Level in SAG Mill

SAGs ORE REDUCTION RATIO

SAG feed size vs intermediate size

SAGs GRINDING CIRCUIT

SABC‐A 23

SABC‐B 2

SABC‐A/B 1

Total Concentrators

26

SAGs MOTOR TYPE

Pinion 5

Gearless 21Total 

Concentrators26

SAGs PRETREATMENT

With precrushing 6Without precrushing 20Total Concentrators 26

CALCULATION METHODOLOGYSize

(Power HP)Millpower

2000 CEET2 SAGDesign JK SimMet SMCPilot/

Industrial Plant

Calculation Method Selected

C1 – L1C1 – L2

33'x15' (10,728) • • Millpower

2000

C1 – L3 40'x22' (28,161) • • •

Pilot/ Industrial

Plant

C4 40'x26' (30,000) • • • • Pilot

C6 38'x20‘ (26,000) • • CEET2

C8 36'x19' (18,000) • • CEET2

C9 – L1C9 – L2C9 – L3

36'x17' (20,000) • • • JK SimMet

C10 36'x15' (16,000) •

Pilot/ Industrial

Plant

C12 40'x23.5' (29,000) • •

Pilot/ Industrial

Plant

C13 – L2 38'x22' (26,000) • •

Pilot/ Industrial

PlantTotal 2 5 0 6 1 7 -

HISTORICAL FOCUS BY DECADE1970s 1980s

• Learn to operate• Sizing to 24’• FAG or SAG?• Mostly DSAG circuit• 4” max ball

• Begin pebble crushing• Sizing to 32’• Single or dual motors• Lining machine• 1.8 ton liner piece max

1990s 2000s• HPGR competitor• 5” max ball• Mobile feeder chute• Lining machine improvements• Gearless motor

• SAG with variable speed• Liner shape optimization• SABC‐A & SABC‐B• Begin use of precrushing• Begin mine  to mill

2010s (current)

• Sizing to 42’ (Toromocho‐Peru) 5.5” max ball• Automation lining machine           Commissioning and start‐up by outsourcing

TRENDS AND RISKS

TRENDS RISK• Start with the SAG and only one ball mill for long period.

• Start without pebble crusher.• Remote start up and operation.

• New projects consider pre‐crushing in the future.

• SAG discharge over screen or trommel‐screen.

• Big motors failure (various cases).

• Frozen charge (liner breaks).• Lubrication system failure (leaks, others).

• Refrigeration system failure.• Deep ores not good for SAG (2 examples).

JRI EXPERIENCE IN COMMISSIONING AND START UP IN CONCENTRATOR PLANTS

Collahuasi Line 3 / ChileApril – June 200462 kt/d SAG Mill 40’

Peñasquito Line 1 / MexicoJune – December 200950 kt/d SAG Mill 38’

Esperanza Project / ChileJanuary 2010 – May 201197 kt/d SAG Mill 40’

INFORMATION SOURCES

The data were collected from various sources,including:

– JRI benchmarking data (1992 to 2014)– JRI design criteria– Other engineering company’s design criteria– Operational diagnostic analysis prepared by JRI– Start up of grinding operation done by JRI– Public reports from Chile, Argentina and Peru– Reliable private information

THANK YOU VERY MUCH