Asante Gold Corporation's Chirano Gold Project in Ghana has implemented a series of plant modifications between 2023 and 2025 designed to increase throughput capacity from the 3.6 Mtpa design rate toward 4.0 Mtpa, with additional upgrades scheduled through 2026.
The Chirano Gold Project is an operating gold mine located in Ghana, West Africa, owned by Asante Gold Corporation. The processing facility at Chirano treats ore from multiple underground mines, including Akwaaba, Suraw, Akoti, Tano, and Obra, as well as open pit sources including Mamnao, Sariehu, and Aboduabo. The plant uses a standard carbon-in-leach (CIL) process for gold extraction. The technical report covering the project carries an effective date of 31 December 2025.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Plant design throughput capacity | 3.6 | Mtpa | Nameplate capacity |
| Target throughput after modifications | 4.0 | Mtpa | Objective of plant modifications |
| Average milled ore 2024 | 3.3 | Mt | Total for production year |
| Total milled ore 2025 (11 months) | 3.2 | Mt | Year-to-date at time of reporting |
| Average crusher throughput rate 2023 | 484 | tph | Annual average |
| Average crusher throughput rate 2024 | 503 | tph | Annual average |
| Average crusher throughput rate 2025 | 559 | tph | Annual average |
| Average mill throughput rate 2023 | 424 | tph | Annual average |
| Average mill throughput rate 2024 | 448 | tph | Annual average |
| Average mill throughput rate 2025 | 475 | tph | Annual average |
| Average mill work index 2024 | 16.6 | kWh/t | Blended mill feed |
| Average mill work index 2025 | 16.1 | kWh/t | Blended mill feed |
| Average gold recovery 2023 | 85.52 | % | From Table 17-1 |
| Average gold recovery 2024 | 86.20 | % | From Table 17-1 |
| Average gold recovery Q4 2025 | 82.98 | % | From Table 17-1 |
| Average head grade 2023 | 1.50 | g/t | From Table 17-1 |
| Average head grade 2024 | 1.40 | g/t | From Table 17-1 |
| Average head grade Q4 2025 | 1.11 | g/t | From Table 17-1 |
| Crusher effective utilisation (3-year average) | 73.3 | % | Exceeds industry standard of 70% |
| Mill effective utilisation (3-year average) | 86.9 | % | Below industry standard of 91.3% |
| Unscheduled mill downtime 2025 | 596 | hours | Equivalent to 24.8 milling days |
| Lost milled throughput from unscheduled downtime | 280,000 | tonnes | 2025 year-to-date |
| CIL pre-leach tank live volume | 3,200 | m3 | From equipment specifications |
| Individual CIL tank live volume | 1,300 | m3 | Nine tanks total |
| Oxygen generation capacity | 10 | tpd | From PSA plant |
| Pre-leach tank agitator power | 160 | kW | Replaced 130kW unit |
| CIL agitator power (upgraded) | 75 | kW | Three tanks, replaced 55kW units |
Overview
The Chirano process plant uses a comminution circuit with three-stage crushing and two-stage ball milling. A standard CIL process extracts gold from the ore. The plant treats a blended feedstock comprising roughly 95% fresh ore and 5% oxide ore. In 2024 the plant feed blend averaged 47% underground ore and 44% open pit ore. For 2025 those proportions shifted to 47% underground and 45% open pit, with oxide ore making up the balance.
Since Asante acquired the Chirano mine, the plant has not reached its 3.6 Mtpa nameplate capacity, averaging approximately 3.3 Mtpa. The planned total milled ore for the completed 2025 production year was 3.5 Mt. The plant modifications described in the technical report aim to close that gap and push throughput beyond the original design rate to 4.0 Mtpa.
Key Process Stages
Ore enters the primary jaw crusher, a Metso C150, in open circuit. Secondary crushing uses one Sandvik S660 CS660 Hydrocone. Two Sandvik H660 CH660 Hydrocone crushers served as tertiary crushers alongside a newer Sandvik CH865i Hydrocone installed in September 2024. Crusher screens are Sandvik XS144 double-deck units.
Mill feed goes to a surge bin with overflow to a dead stockpile for mechanical reclaim. The primary ball mill, a converted SAG mill with grate discharge measuring 6.0 metres diameter and 5.7 metres effective grinding length, runs at 2,900 kW. Two secondary ball mills operate in closed circuit with cyclone clusters. Secondary ball mill number one is an overflow discharge unit 4.88 metres in diameter with 6.83 metres effective grinding length at 2,500 kW. Secondary ball mill number two was converted from a SAG mill to overflow configuration, 6.10 metres diameter with 7.0 metres effective grinding length at 2,500 kW.
A centrifugal gravity concentrator, a Knelson QS48, draws a bleed stream from the secondary mill discharge with a scalping screen to remove oversize. An intensive leach reactor processes the gravity concentrate. Primary mill scats go through in-circuit crushing.
Cyclone overflow passes through trash screening and thickening before leaching. The pre-leach tank receives oxygen from a PSA plant generating 10 tonnes per day. An Aachen shear reactor installed in March 2024 operates on the 3,200 cubic metre pre-leach tank. Nine CIL tanks follow, each 12 metres diameter by 12 metres height with flat bottoms and 1,300 cubic metre live volumes. The pre-leach tank agitator was upgraded to a 160 kW dual hydrofoil impeller unit in August 2024. The first three CIL tanks received upgraded 75 kW dual hydrofoil impeller agitators at the same time.
Two Zadra elution circuits operate with dedicated acid wash columns and regeneration kilns. The gold room houses three elution eluate electrowinning cells plus a dedicated gravity electrowinning cell. Carbon screening of CIL tails precedes disposal of tailings to a clay-lined tailings storage facility.
Additional Interesting Data and Summary
The crusher plant averaged 73.3% effective utilisation across 2023, 2024, and 2025, exceeding the industry standard of 70% or 6,100 hours per annum. The milling plant's effective utilisation averaged 86.9% over the same period, below the industry standard of 91.3% or 8,000 hours per annum.
Total mill plant downtime for 2025 year-to-date was 860 hours. Scheduled plant maintenance accounted for 264 hours. Power outages caused 46 hours of downtime. Mill 1 motor electrical faults and mill oil lubrication faults totalled 89 hours. Commissioning of the new cyclone cluster required 55 hours. CV-02 feed conveyor repairs took 76 hours. Mechanical repairs to the thickener and operational issues contributed 38 hours. TSF water supply shortage caused 19 hours of downtime. Excluding scheduled maintenance, major downtimes totalled 323 hours. An additional 273 hours came from 35 unscheduled mill stoppages. Total unscheduled milling plant downtime reached 596 hours.
The average monthly milled tonnage increased from 275,000 tonnes per month in 2023 and 2024 to 295,000 tonnes per month in 2025. Average gold recovery for 2023 was 85.52% at an average head grade of 1.50 g/t. In 2024 recovery improved to 86.20% at 1.40 g/t head grade. For the fourth quarter of 2025, average recovery was 82.98% at 1.11 g/t head grade.
The mill feed grind size, measured at 106 micrometres, averaged 80.42% passing in 2023, 81.88% in 2024, and 83.87% in the fourth quarter of 2025. The operating work index averaged 16.62 kWh/t in 2024 and 16.30 kWh/t in the fourth quarter of 2025.
An average crushed throughput rate of 600 tonnes per hour was achieved in the last half of the 2025 production year. This figure excludes an additional 145,000 tonnes per month of crushed rock supplied to the rehandle stockpile from the remote ROC plant and from a mobile crusher at the plant site. At 75% effective utilisation and 600 tonnes per hour, the crusher plant capacity reaches 4.0 Mtpa with backup supply from remote crushers.
After the cyclone modification in the second quarter of 2025, the milling feed rate ramped to 500 tonnes per hour but was reduced to 475 tonnes per hour. Higher slurry flow rates at 500 tonnes per hour exposed a bottleneck in the CIL plant. At 89% effective utilisation and a milling throughput rate of 510 tonnes per hour, the milling circuit capacity is 4.0 Mtpa.
The 448 tonnes per hour average mill throughput for 2024 was 27 tonnes per hour lower than the 475 tonnes per hour average for 2025. The 2025 blended mill feed had a softer ore with an average mill work index of 16.1 kWh/t compared to 16.6 kWh/t for 2024. Higher milling rates of 501 tonnes per hour in the first quarter of 2025 and 478 tonnes per hour in the third quarter corresponded to softer work indices of 15.64 kWh/t and 15.84 kWh/t respectively.
Key Processes
- Three-stage crushing circuit with primary jaw crusher, secondary cone crusher, and tertiary cone crushers including a larger Sandvik CH865i Hydrocone installed September 2024
- Two-stage ball milling circuit with primary ball mill converted from SAG mill and two secondary ball mills
- Gravity concentration circuit with Knelson concentrator commissioned December 2023
- Intensive leach reactor for gravity concentrate gold extraction with dedicated electrowinning cell
- Pre-leach tank with Aachen shear reactor using oxygen from 10 tpd PSA plant
- Nine carbon-in-leach tanks with upgraded agitators and interstage pumping screens
- Two Zadra elution circuits with acid wash columns and regeneration kilns
- Gold room with three elution electrowinning cells and one gravity electrowinning cell
- Carbon screening of CIL tails with clay-lined tailings storage facility disposal
Future plant modifications include installation of a vibrating grizzly screen in the third quarter of 2026 to remove fine material from the jaw crusher feed. Upgrades to the remaining six of nine CIL tanks will continue through the first to fourth quarters of 2026, installing uprated agitators, new double interstage pump screens, larger inter-tank launders, and carbon transfer pumps to remove the 4.0 Mtpa flow rate bottleneck.
Source: NI 43-101 Technical Report and Updated Mineral Resource Estimate, Asante Gold Chirano Ltd., Ghana, West Africa, 31 December 2025. Project website: Chirano Gold Project
Consolidated report summaries
The following former standalone pages about this operation were consolidated here on October 25, 2026. They are retained for source traceability; dates and figures reflect each report’s own effective date and may be superseded by the current information above.
Chirano Gold Mines Limited — 2024 Technical Report
This NI 43-101 technical report presents updated mineral resources and processing information for the Chirano Gold Mine in Ghana, effective 31 December 2023.
Report context
This technical report and updated Mineral Resource Estimate for Chirano Gold Mines Limited, which operates the Chirano Gold Mine in Ghana, West Africa, was prepared on behalf of Asante Gold Corporation. The effective date is 31 December 2023 and the issue date is 30 April 2024. The report is compliant with National Instrument 43-101 and Form 43-101F1. The Chirano Gold Mine has been in production since 2005 and has produced over 2.8Moz of gold since 2010 up to the end of 2023. Current life of mine is five years.
Processing route
Overall process description
The Chirano processing plant comprises a 3.6Mtpa milling and carbon-in-leach (CIL) processing circuit with associated infrastructure including tailings storage facilities. The plant processes ore from both open pit and underground operations.
Gravity circuit
A gravity concentration circuit was implemented in November 2023. The estimated gravity concentration recovery from 2023 test work is 10.5%. This resultant 10% reduction in the CIL head grade by gravity concentration mitigates recovery losses associated with coarse gold dissolution in the leaching circuit. The estimated overall gold recovery improvement from gravity concentration is in the range of 0.5% to 1.0%.
Intensive leach reactor
The plant includes an intensive leach reactor for processing gravity concentrate. Electrowinning is used for gold recovery from solution.
Current plant modifications
Modifications completed or planned include:
- Gravity circuit (installed November 2023)
- Pebble crusher
- Pressure Swing Adsorption (PSA) oxygen plant
- Shear reactor circuit (planned Q1 2024)
- Pre-leach and CIL agitators upgrade (planned Q2 2024)
- Mill cyclones upgrade (planned Q2 2024)
- Fine tertiary cone crusher (planned H1 2024)
Reagents
Reagents used in the processing plant include flocculant, Goldilox, hydrogen peroxide, caustic soda, and sodium cyanide.
Plant process services
Raw water and process water systems are in place, along with compressed air supply.
Plant gold recovery performance (2022-2023)
For the period August 2022 to September 2023, the plant processed an average of 285,289 tonnes per month in 2022 and 278,531 tonnes per month in 2023. Average feed grades were 1.34 g/t Au in 2022 and 1.47 g/t Au in 2023, with overall gold recoveries of 88% and 86% respectively.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Plant throughput capacity | 3.6 Mtpa | Design |
| Plant throughput (2022) | 3,423,470 tonnes | Actual operating data |
| Plant throughput (2023) | 3,296,882 tonnes | Actual operating data |
| Average feed grade (2022) | 1.34 g/t Au | Actual operating data |
| Average feed grade (2023) | 1.47 g/t Au | Actual operating data |
| Overall gold recovery (2022) | 88% | Actual operating data |
| Overall gold recovery (2023) | 86% | Actual operating data |
| Estimated gravity recovery | 10.5% | Testwork (2023) |
| Estimated overall recovery improvement from gravity | 0.5% – 1.0% | Estimated from testwork |
| Aboduabo oxide gold recovery (base case leach) | 87.8% – 93.5% | Testwork (Q4 2023) |
| Gold leached by direct cyanidation (tails sample) | 5.3% | Diagnostic leach test (2023) |
| Mild oxidative pre-leached gold extraction (tails sample) | 16.6% | Diagnostic leach test (2023) |
| Total gold recoverable from tails with shear reactor | 21.9% | Diagnostic leach test (2023) |
Project website: https://www.asantegold.com/operations/chirano
Technical qualifications
The qualified persons have not researched property title or mineral rights for the project and express no opinion as to the validity of ownership status of the property. The technical report has been prepared on the understanding that the current operations and property are, or will be lawfully accessible for evaluation, development, mining and processing. The qualified persons are independent of Asante Gold Corporation and there is no circumstance that could interfere with any judgments made in this technical report.
Source: NI 43-101 Technical Report and Updated Mineral Resource Estimate, Chirano Gold Mines Limited, Ghana, West Africa, effective date 31 December 2023, issue date 30 April 2024.
Chirano Gold Mine — 2022 Technical Report
This report describes the process plant design, current operating performance, and process description for the Chirano gold mine in Ghana.
Report context
The Chirano gold mine, originally developed by Red Back Mining, commenced commercial production in October 2005 and was acquired by Kinross in September 2010. The mine comprises the Akwaaba, Suraw, Akoti South, Akoti North, Akoti Extended, Paboase, Tano, Obra South, Obra, Sariehu and Mamnao open pits and the Akwaaba and Paboase underground mines. In 2008 the plant was expanded to a design throughput capacity of 3.5 Mtpa by Lycopodium Engineering. This technical report is dated 30 September 2022.
Processing route
Background
The Chirano plant has been treating ore at approximately 3.4 Mtpa from the various pits and underground as a blend comprised of both fresh and oxide ore.
Plant Design
The Chirano process plant is comprised of the following circuits:
- Primary crushing of run-of-mine (ROM) material in open circuit
- Secondary and Tertiary crushing in closed circuit with screening
- Mill feed surge bin with an overflow feed to a dead stockpile for mechanical reclaim
- Open circuit primary ball mill operating with two parallel secondary ball mills in closed circuit with cyclones
- In-circuit crushing of the primary mill scats
- Trash screening and thickening of cyclone overflow before leaching
- Gold leaching in a single pre-leach tank followed by nine CIL tanks
- Two Zadra elution circuits with dedicated acid wash columns and regeneration kilns
- Gold room housing three electrowinning cells
- Carbon screening of the CIL tails followed by disposal of tailings to an unlined TSF.
Process Description
Crushing
The crushing circuit includes a primary jaw crusher, a secondary cone crusher, and three tertiary cone crushers. Crusher screens are provided as part of the closed-circuit arrangement.
Milling
The milling circuit consists of one grate-discharge primary ball mill (converted from a SAG mill) and two secondary ball mills (one overflow design and one converted from a SAG mill to overflow design). The primary mill scats are processed through an in-circuit crusher.
Gravity Circuit
The gravity circuit is noted as de-commissioned.
Pre-Leach Thickening
Cyclone overflow is directed to a pre-leach trash screen followed by an 18 m diameter high-rate pre-leach thickener.
Carbon in Leach
Gold leaching is conducted in a single pre-leach tank of 3,200 m³ live volume, followed by nine CIL tanks each of 1,300 m³ live volume. All tanks are flat-bottomed with dual hydrofoil impeller agitators.
Tailings Disposal
Carbon screening of the CIL tails occurs prior to disposal of tailings to an unlined tailings storage facility.
Carbon Treatment
Two Zadra elution circuits are provided, each with a dedicated acid wash column (5 t carbon capacity, mild steel butyl rubber lined) and elution column (5 t carbon capacity, 304 stainless steel). Two regeneration kilns are installed, each horizontal tube type (321 SS) rated at 250 kg/h, diesel-fired.
Electrowinning
Electrowinning cells are installed as part of the elution circuits. The gold room houses three electrowinning cells.
Gold Room
The gold room contains the electrowinning cells for gold recovery from the elution circuits.
Reagents
Cyanide and lime are consumed in the process, with consumption rates reported in the plant performance data.
Plant Process Services
Plant process services are provided to support the above circuits.
Key reported parameters
| Parameter | Unit | Design Value | Operating Data (Nov 2021 – Apr 2022) | Testwork Basis |
|---|---|---|---|---|
| Plant throughput capacity (design) | Mtpa | 3.5 | , | As designed by Lycopodium Engineering (2008) |
| Actual milling rate | Mtpa | , | ~3.4 | Historical operating data |
| Head grade (monthly range) | g/t | , | 1.14 – 1.51 | Six-month operating data |
| Gold recovery (monthly range) | % | , | 84.77 – 88.63 | Six-month operating data |
| Cyanide consumption (monthly range) | kg/t | , | 0.16 – 0.24 | Six-month operating data |
| Lime consumption (monthly range) | kg/t | , | 1.21 – 1.92 | Six-month operating data |
| Crushing circuit availability (monthly range) | % | , | 72.8 – 91.2 | Six-month operating data |
| Crushing circuit effective utilisation (monthly range) | % | , | 74.0 – 78.0 | Six-month operating data |
| Milling circuit availability (monthly range) | % | , | 89.7 – 96.1 | Six-month operating data |
| Milling circuit effective utilisation (monthly range) | % | , | 86.9 – 92.1 | Six-month operating data |
Project website: https://www.kinross.com/news-and-investors/news-releases/press-release-details/2022/Kinross-completes-sale-of-Chirano-mine-in-Ghana/default.aspx
Technical qualifications
This technical report presents the Chirano process plant as described by the original designer Lycopodium Engineering for the 2008 expansion. The operating data represents historical performance from November 2021 to April 2022 and does not constitute a feasibility study or production forecast. The gravity circuit is reported as de-commissioned with no replacement or modification described. No testwork programs are described in the recovery methods section. The report does not include detailed metallurgical testwork data, life-of-mine planning, or economic analysis within the processing sections reviewed.
Source: NI 43-101 Technical Report on Chirano Gold Mine, Ghana, 30 September 2022, Section 17.
