Haile Gold Mine Recovery: Flotation & CIL Processing
Source: OceanaGold Corporation (2026)
Website: https://oceanagold.com/operations/haile
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Throughput | 3.0 | Mt/yr | Scheduled mill rate over life of mine; peak monthly rates of 479 t/h achieved (equivalent to ~3.8 Mt/yr) |
| Mill Power | Not specified | ||
| Target Grind Size | 75 | μm (P80) | Primary grinding circuit product size; regrind target P80 of 13 μm for flotation concentrate |
| Head Grade | 1.7 | g/t | Typical fresh ore gold feed grade used in recovery model; average sulfur feed grade 0.4% with max monthly 2.1% |
| Recovery % | Not specified | % | Overall gold recovery tracked well with site model; flotation sulfur recovery 70-90% |
| Processing Capacity | 3,000,000 | t/yr | Nominal capacity after debottlenecking; design basis for regrind circuit 4 Mt/yr at 5% sulfur |
| Energy Consumption | Not specified | kWh/t | |
| Water Consumption | Not specified | m³/t | Main water requirements satisfied by internal recycle from thickeners and TSF decant |
| Operating Hours | 24 | hours/day | Continuous operation; SAG mill utilization 84%-89% historically, targeting 92% |
Overview
OceanaGold operates the Haile Gold Mine in Lancaster County, South Carolina, using a conventional flotation and cyanide leaching (CIL) flowsheet that commenced commercial operation in 2017. The plant originally had a nameplate capacity of 2,300,000 tonnes per year (t/yr) and has been systematically debottlenecked to treat up to 3,800,000 t/yr depending on ore competency. The facility processes a blend of fresh and oxidized sulfide ores from open pit and underground sources, achieving scheduled mill rates of 3.0 million tonnes per annum (Mt/yr) over the life of mine. Gold recovery methods at Haile rely on a SAG-ball mill-pebble crusher (SABC) circuit for primary grinding to a target P80 of 75 microns, followed by flash and rougher flotation to recover sulfide minerals. The flotation concentrate undergoes two-stage fine grinding in a tower mill and an IsaMill to a P80 of 13 microns before cyanide leaching. Flotation tailings are also leached to recover soluble gold. Overall gold recovery has tracked well with the site model, with leach performance primarily influenced by concentrate regrind size and carbon activity. The plant produces gold-silver doré bars as final product and includes a contact water treatment plant to manage environmental discharge. A major upgrade to separate concentrate leaching with a Carbon-in-Pulp (CIP) circuit and extend residence time to 96 hours is planned for 2028, adding approximately 63,000 ounces of gold recovery.
Key Process Stages
- Stage 1: Crushing and Conveying — Run-of-mine ore is fed via apron feeder to a vibrating grizzly, with oversize crushed by a primary jaw crusher to minus 100 mm. Crushed ore and grizzly fines are conveyed to a coarse ore surge bin or an emergency stockpile for reclaim.
- Stage 2: Grinding and Classification — A SAG-ball mill-pebble crusher (SABC) circuit grinds ore in closed circuit with vibrating screens and hydrocyclones. The target primary grind size is P80 of 75 microns. Pebble crusher (Sandvik CH-440) and SAG mill grate redesign improve handling of competent ore.
- Stage 3: Flotation — Flotation reagents (SIBX and frother) are added in the grinding circuit. A flash flotation cell recovers a portion of sulfides from the ball mill circulating load, followed by bulk rougher flotation to recover the balance. Combined concentrate reports to the regrind circuit.
- Stage 4: Concentrate Regrinding — Flotation concentrate is reground in two stages: first, an ETM-1500 tower mill (1.2 MW) in closed circuit with cyclones to P80 <40 microns; second, an M10000 IsaMill (3 MW) in closed circuit with cyclones to a target P80 of 13 microns.
- Stage 5: Cyanide Leaching and Gold Recovery — Reground concentrate is thickened, pre-aerated, and leached in a CIL circuit with activated carbon. Gold and silver are stripped from loaded carbon by hot caustic-cyanide solution, recovered by electrowinning, and smelted into doré bars. CIL tailings are thickened, detoxified, and pumped to a lined tailings storage facility.
Additional Interesting Data and Summary
The Haile Gold Mine processing facility has undergone continuous optimization since commissioning in 2017, including installation of a pebble crusher, two-stage fine grinding circuit upgrades (1.2 MW tower mill and 3 MW IsaMill), and replacement of thickener internals. The contact water treatment plant (CWTP) treats mine contact water via pH adjustment, clarification, microfiltration, and a newly added reverse osmosis stage (2025) to meet Whole Effluent Toxicity limits, increasing treatment capacity from 1,100 gpm to 2,640 gpm. Brine from RO is pumped to the tailings dam, with Minetek evaporators being recommissioned for pool control. A major USD 45 million concentrate leach circuit upgrade is planned, adding four 750 m³ leach tanks and a Kemix Carousel CIP system to extend concentrate residence time to 96 hours, targeting an additional 63,000 ounces of gold recovery. The upgrade will be completed by Q1 2028 ahead of Ledbetter Underground ore processing. Operating costs are budgeted at US$23.28 per tonne milled, including US$2.13 for water treatment, with inflationary pressures on reagents, labor, and electricity. Key consumable rates include 0.664 kg NaCN/tonne, 1.45 kg lime/tonne, and 0.441 kg flocculant/tonne. The plant processes 2.8–3.0 Mt/yr of ore from open pit (Ledbetter, Snake, Haile phases) and underground sources, targeting 200–220 koz gold production annually from 2028. Future sustainability initiatives include engineering rectifications to improve mill utilization above 90% and implementation of the Andritz expert system for SAG mill, ball mill, cyclone, thickener, and cyanide destruction control. The site-specific comminution model developed from SMC and Bond work index testing has enabled accurate throughput forecasting for deeper, more competent ores, with geometallurgical testing using Geopyora on 72 core intercepts supporting the reduced throughput expectation in the life-of-mine plan.
Key Processes: Flotation, CIP/CIL, Cyanidation, SAG Mill, Ball Mill, Crushing
Target Commodities: Gold, Silver
