The report describes two operational concentrators at Cadia Operations that employ distinct comminution and flotation circuits to produce a copper-gold concentrate and on-site gold doré.
Report context
This technical report, dated 2020, covers the Cadia Operations in New South Wales, Australia. It was prepared in accordance with NI 43-101 standards and describes the processing facilities and recovery methods as they existed at the time of reporting, along with certain proposed expansions.
Processing route
Concentrator 1
Concentrator 1 was commissioned in 1998 using a conventional semi-autogenous grinding (SAG) mill, pebble crush and ball mill (SABC) circuit and had a design capacity of 17 Mt/a. This circuit was upgraded in 2012 for the processing of Cadia East ore with the addition of a high-pressure grinding rolls (HPGR) circuit and third processing train to achieve a design capacity of 20 Mt/a. Concentrator 1 currently operates at a nominal rate of 23 Mt/a with the improved rate the result of several operational improvements.
The concentrator consists of: a gyratory crusher crushing excess ore stockpiled on the surface; a screening plant; two cone crushers for secondary crushing of screen oversize; a HPGR for further size reduction ahead of SAG milling; a single 20 MW SAG mill in open circuit configuration with oversize pebbles returning to the screening plant; three ball mills in closed circuit with hydrocyclones; flash flotation and gravity concentrator processing of hydrocyclone underflow, gravity concentrator processing of flash flotation concentrate; and rougher and scavenger flotation of the slurry from three ball mill circuits (i.e. flotation trains 1, 2, and 3) with concentrate reporting to regrind mills; a coarse ore flotation circuit using HydroFloat technology on train 3 rougher tailings; cleaner flotation circuits using both conventional and Jameson cell technology; and thickening of rougher tailings before pumping to the tailings storage facilities.
Concentrator 1 uses approximately 60% of the site total power consumption.
Concentrator 2
Concentrator 2 was commissioned in 2002 using fully autogenous grinding (AG) and had a target capacity of 4 Mt/a. This concentrator has undergone several upgrades since commissioning, including a conversion to SAG milling, the addition of a Vertimill in a tertiary milling duty, additional regrind capacity, the addition of secondary and tertiary crushing ahead of the SAG mill, and flotation circuit debottlenecking. It currently operates at a rate of 7 Mt/a.
The concentrator consists of: an overland conveyor system transporting ore from the main coarse ore stockpile (COS) to the processing plant; secondary and tertiary crushing using conventional cone crushers; a SAG mill in closed circuit with two pebble crushers; a ball mill and Vertimill (0.93 MW) in closed circuit with hydrocyclones for secondary grinding; another Vertimill (2.2 MW) for tertiary grinding; flash flotation and gravity concentrators processing hydrocyclone underflow; additional gravity concentrator treating flash flotation concentrate; and rougher and scavenger flotation (conventional cells) processing grinding circuit product; regrind mill; cleaner flotation stages utilising both conventional and Jameson flotation cells; thickening of rougher tailings before pumping to tailings storage facility; and thickening of final gold/copper concentrate product.
Concentrator 2 uses a further 15% of the site total power consumption.
Combined product and water supply
The combined, thickened copper concentrate slurry, with a grade of 23–26% copper, is pumped to Blayney where it is filtered and railed to Port Kembla before export. Approximately 15% of the gold in feed ore is recovered from the gravity concentrator product via shaking tables and then smelted on site to produce gold doré for sale.
The processing plant uses a combination of on-site recycled water (e.g. thickener overflow and TSF return water) and make-up water. Sources have included Cadiangullong Dam, Rodds Creek Water Holding Dam, and Belubula.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Concentrator 1 design capacity (original) | 17 Mt/a | Original design |
| Concentrator 1 design capacity (post-2012 upgrade) | 20 Mt/a | Proposed design after HPGR addition |
| Concentrator 1 current nominal operating rate | 23 Mt/a | Actual operating data |
| Concentrator 2 target capacity (original) | 4 Mt/a | Original design |
| Concentrator 2 current operating rate | 7 Mt/a | Actual operating data |
| Combined concentrator capacity (current) | 30 Mt/a | Actual operating data |
| Combined concentrator capacity (envisaged increase) | 33 Mt/a | Proposed design |
| Combined concentrator capacity (envisaged upper limit) | 35 Mt/a | Proposed design |
| Concentrator 1 SAG mill power | 20 MW | Design specification |
| Concentrator 2 secondary grinding Vertimill | 0.93 MW | Design specification |
| Concentrator 2 tertiary grinding Vertimill | 2.2 MW | Design specification |
| Copper concentrate grade | 23–26% Cu | Actual/expected product |
| Gold recovery from gravity concentrator | ~15% of feed ore | Actual operating data |
| Site power consumption – Concentrator 1 | ~60% | Actual operating data |
| Site power consumption – Concentrator 2 | ~15% | Actual operating data |
Project website: https://www.cadiavalley.com.au/
Technical qualifications
Recent studies envisage increasing total combined plant capacity from 30 Mt/a to 33 Mt/a, and up to 35 Mt/a. Higher plant throughput will be achieved through debottlenecking projects such as the installation of a third secondary crusher and associated conveyor upgrades for Concentrator 1. In the case of Concentrator 2, debottlenecking is to include upgrades to the secondary and tertiary crushers and associated conveyors, and upgrade to primary cyclone feed pumps and cyclones. Studies have commenced to investigate downstream flotation and dewatering requirements to handle the planned higher throughputs. Additional tertiary milling and rougher flotation capacity will assist in maintaining or improving overall plant recovery. The Concentrator 1 upgrade is likely to see the further use of a coarse ore flotation circuit treating combined train 1 and 2 rougher tailings with the reground concentrate processed via existing and new flotation cells.
These throughput increases and associated equipment additions remain at the study stage and are described as envisaged, not as currently installed or operating.
*Source: Cadia Operations , 2020 Technical Report, Section 1.15 Recovery Methods*
