Overview
The T.F.G. NO. 1 mine, colloquially identified in technical documentation as the Tomingley Gold Operations (TGO), represents a cornerstone of mineral processing excellence in New South Wales, Australia. Located approximately 50 kilometers southwest of Dubbo in the Central West region, this facility has undergone a transformative multi-stage expansion designed to pivot from traditional free-milling oxide processing to a complex, high-throughput circuit capable of handling refractory sulfide ores. Owned and operated by Mandalay Resources (following recent technical commissions) or its associated entities in the Tomingley Gold Project (TGP) portfolio, the mine is strategically positioned to exploit several key deposits, including Wyoming One, Wyoming Three, Caloma, and the more recently discovered Roswell and San Antonio systems.
The significance of the T.F.G. NO. 1 project lies in its recent “Stage 1” and “Stage 2” upgrades, which were engineered to increase annual throughput from a baseline of 1.0 million tonnes per annum (Mtpa) to a target of 1.5 Mtpa. This expansion was necessitated by the depletion of easily accessible oxide materials and the transition into deeper, fresh rock where gold is predominantly associated with sulfides, specifically pyrite and arsenopyrite. The technical handover of the Stage 1 expansion occurred on November 18, 2024, marking a new era of metallurgical capability for the site. By integrating advanced flotation and ultra-fine regrinding technologies, the T.F.G. NO. 1 circuit now stands as a model for regional gold processing, balancing increased complexity with operational efficiency and environmental stewardship.
Key Process Stages
The mineral processing circuit at T.F.G. NO. 1 is characterized by a sophisticated multi-stage flowsheet that combines conventional gravity separation with modern flotation and fine-grinding techniques. The recent upgrades have introduced critical parallel circuits to handle the increased tonnage and mineralogical complexity of the refractory feed.
- Primary and Secondary Crushing: The circuit initiates with a high-capacity primary jaw crusher, followed by secondary cone crushing. This two-stage arrangement ensures a consistent feed size for the downstream grinding mills.
- Two-Stage Grinding Circuit: Historically a single ball mill operation, the expansion has provisioned a parallel semi-autogenous grinding (SAG) mill. This allows for a significant increase in capacity to 1.5 Mtpa while providing the necessary power to handle harder, fresh rock composites.
- Classification and Gravity Recovery: Milling discharge is classified via a standard hydrocyclone cluster. A portion of the cyclone underflow reports to a gravity concentrator. The resulting gravity concentrate is treated in an Intensive Leach Reactor (ILR), with gold subsequently recovered through electrowinning and smelting.
- Rougher Flotation: In a major departure from the original flowsheet, the cyclone overflow is now diverted to a new flotation circuit. This stage produces a sulfide-rich rougher concentrate, capturing gold that would otherwise be lost in a standard cyanide leach. The design mass split intends for approximately 15% of the flotation feed mass to report as concentrate.
- Ultra-Fine Regrinding (ISAMill): The rougher concentrate is ground to a P80 of 12 µm using an ISAMill. This ultra-fine grinding is essential for liberating gold encapsulated within the sulfide matrix, ensuring high recovery rates during the final leaching stage.
- Carbon-In-Leach (CIL): Both the reground concentrate and the flotation tailings report to a pre-leach thickener before proceeding to a hybrid CIL circuit. This circuit utilizes cyanide leaching and activated carbon adsorption to recover the remaining gold.
- Elution and Gold Recovery: Loaded carbon from the CIL tanks is stripped in the elution circuit, and the gold is recovered in a secure gold room via electrowinning and smelting.
Critical Data
The following table summarizes the key operational parameters and design specifications for the T.F.G. NO. 1 processing facility following the Stage 2 expansion completion.
| Parameter | Value | Unit |
|---|---|---|
| Design Throughput (Expansion Target) | 1.5 | Mtpa |
| Commissioning Date (Stage 1) | November 2024 | Date |
| Primary Classification Size (P80) | 106 | µm |
| Regrind Target Size (P80) | 12 | µm |
| Metallurgical Gold Recovery | 87.0 | % |
| Flotation Mass Split to Concentrate | 15.0 | % |
| TSF Capacity Extension | 10.5 | Mt |
| Operational Availability (Milling) | 91.3 | % |
Technical Details and Sustainability
The technical evolution of the T.F.G. NO. 1 circuit is driven by the mineralogical challenges presented by the Wyoming, San Antonio, and Roswell deposits. Extensive metallurgical testwork conducted by ALS Metallurgy (Reports A20087 and A23832) identified that a significant portion of the gold is “locked” within sulfide minerals. Traditional Carbon-In-Leach (CIL) methods alone were insufficient for achieving economic recoveries as the mine progressed into fresh, unweathered ore. The implementation of the ISAMill for ultra-fine grinding (UFG) to 12 microns is a critical technical differentiator, allowing for the chemical oxidation and subsequent leaching of refractory gold particles that were previously considered unrecoverable.
From a sustainability and environmental perspective, T.F.G. NO. 1 has implemented a robust Tailings Storage Facility (TSF) management plan. The current paddock-type TSF utilizes a multi-spigot distribution system to ensure even settlement and optimize water recovery. Technical assessments indicate that while the current approved storage is sufficient until mid-2027, an additional 10.5 million tonnes of capacity is achievable through a planned dam wall raise to its full design height. This proactive approach to tailings management is coupled with a commitment to water recycling, where decant water from the TSF is returned to the process circuit to minimize raw water consumption from local sources.
Energy efficiency is another focal point of the technical design. The transition to a SAG/Ball mill configuration was supported by Front-End Engineering Design (FEED) reports from MACA Interquip, focusing on optimizing power draw across the 1.5 Mtpa circuit. The site’s electrical infrastructure is supplied via a high-voltage grid connection, supplemented by on-demand diesel generation to ensure stability during peak loads. Furthermore, the mine maintains a high level of community engagement in the New South Wales region, balancing its industrial expansion with environmental safeguards and local economic contributions. Looking ahead, the integration of Stage 2 upgrades—including additional pregnant liquor tanks and upgraded electrowinning cells—will further solidify T.F.G. NO. 1 as a resilient, high-capacity gold producer capable of navigating the metallurgical complexities of the Tasmanide gold belts.
Source: T.F.G. NO. 1 | Tomingley Gold Project Technical Reports 2024-2025
Source: NI 43-101 Technical Report
This article provides an overview of mineral processing developments based on publicly available technical reports and industry analysis.
