Quartz Mountain Gold: Oxide Heap Leach & Sulphide Flotation Recovery

Source: Q-Gold Resources Ltd (2026)
Website: https://qgoldresources.com/project/quartz-mountain

Critical Data

Overview

The Quartz Mountain Gold Project, owned by Q-Gold Resources Ltd., is located in Lake County, Oregon, USA. The site encompasses two deposits—Crone Hill and Quartz Butte—containing 108 million tonnes of mineral resource. A Preliminary Economic Assessment (PEA) effective April 2026 outlines a hybrid gold recovery strategy tailored to the ore’s dual mineralogy: near-surface oxide material amenable to cyanide leaching, and deeper sulphide refractory material requiring flotation concentration. Metallurgical testing confirmed that direct cyanidation of sulphides is uneconomical, so two independent processing circuits are planned. The oxide circuit will process 20,000 tonnes per day through a three-stage crushing plant to produce a P80 of 12.5 mm, agglomerated with cement and lime, then stacked in 7.5-meter lifts on a lined heap leach pad. Dilute cyanide solution is applied at 8.5 L/hr-m² over a 105-day leach cycle. Gold and silver are recovered via carbon adsorption, desorption, electrowinning, retorting, and smelting to produce doré bars, with an average recovery of 79.6% over the life of mine. The sulphide refractory material will be processed in a flotation plant to generate a commercially saleable concentrate for off-site autoclaving, roasting, or smelting under a toll-processing agreement. Both circuits will share the crushing facility and stockpile infrastructure, with oxide material processed first to capitalize on its near-surface location. The project is significant for its integrated approach to treating mixed gold ore types, optimizing overall recovery while minimizing capital expenditure and environmental footprint. Key process design criteria include a crushing availability of 75%, a leach pad with up to eight lifts (60 m maximum height), and a zero-discharge solution management system incorporating pregnant and event ponds.

Key Process Stages

• Stage 1: Three-Stage Crushing – Run-of-mine ore from Crone Hill and Quartz Butte pits is dumped into a feed bin with an apron feeder and vibrating grizzly (100 mm scalping). Oversize passes through a primary jaw crusher (160 mm closed-side setting), then secondary and tertiary crushing circuits. The secondary circuit uses a standard cone crusher in open circuit with a double-deck screen (95 mm and 45 mm openings). The tertiary circuit includes two short-head cone crushers in closed circuit with double-deck screens (35 mm and 18 mm openings), producing a final product P80 of 12.5 mm. Dust control via water sprays and dry collection systems is installed at all transfer points.
• Stage 2: Reclaim and Stacking – Crushed product is reclaimed by belt feeders and conveyed to the stacking system. Lime (5.9 kg/t) is metered for pH control and cement (7.3 kg/t) for agglomeration. The mobile conveyor stacking system comprises ramp conveyors, grasshopper conveyors, an index feed conveyor, a horizontal index conveyor, and a radial stacker. Material is stacked in 7.5-meter-high lifts in cells 260 feet wide. After drainage, lower lifts are cross-ripped before adding new lifts to ensure random solution flow. Up to eight lifts (60 m total height) are planned.
• Stage 3: Solution Application and Storage – Barren solution (dilute NaCN at 150–250 ppm) is pumped at 8.5 L/hr-m² through drip emitters onto the active heap. The leach cycle is 105 days. Pregnant solution drains by gravity to a pregnant solution tank (15-minute retention) via a lined collection ditch. Overflow from pregnant and barren tanks flows to a pregnant solution pond and an event/overflow pond. The pad is lined with compacted clay overlain by 80-mil LDPE; ponds have geosynthetic clay liner plus 80-mil and 60-mil HDPE membranes. Leak detection systems are installed between liners.
• Stage 4: Carbon Adsorption (CIC) – Pregnant solution is pumped to two trains of five cascade-type, open-top carbon adsorption columns (5.4 tonnes carbon each). Solution flows by gravity through the series of columns, where gold and silver are adsorbed onto activated carbon. Barren solution exits the last column through a safety screen and returns to the barren tank. Magnetic flowmeters and continuous samplers monitor efficiency. Loaded carbon from the lead column is transferred to acid wash using a screw impeller pump, with carbon advanced counter-currently.
• Stage 5: Desorption, Electrowinning, and Smelting – Loaded carbon undergoes acid washing (dilute HCl, pH 1.0–2.0) to remove scale and contaminants. After rinsing, carbon is stripped in a high-temperature elution circuit coupled to electrowinning cells. Precious metal sludge is collected, retorted to recover mercury, and smelted to produce doré bars. Mercury is stored onsite for eventual disposal. Carbon is thermally reactivated in a rotary kiln after each elution batch. The ADR plant operates indoors with semi-automatic controls and local HMI panels.

Additional Interesting Data and Summary

The Quartz Mountain Gold Project’s Recovery Methods section provides a comprehensive framework for processing a complex gold resource that includes both oxide and sulphide refractory ores. For the oxide circuit, the water balance analysis is based on 45 years of precipitation data from an adjacent SNOTEL station and pan evaporation records. The model predicts a net annual water deficit under average, wet, and dry conditions, requiring make-up water of 18 to 120 m³/hr (average 56 m³/hr). A zero-discharge system is achieved through lined ponds—pregnant solution pond (94,000 m² collection area) and event pond—with double liners and leak detection. The leach pad itself covers 187,000 m² of active area, with 752,000 m² of lined pad and ditch collection area. Retained moisture after drain-down is 11.8%, and material moisture varies seasonally between 3% and 6%. An antiscalant polymer is added to prevent scaling in the irrigation system. Environmental safeguards include buried drip emitters during winter (≥3 feet below surface) to prevent freezing, heat-traced barren solution headers, and extensive dust suppression at crushing transfer points. The recovery plant’s ADR circuit operates with two carbon column trains, each handling 904 m³/hr nominal flow (1,084 m³/hr design). Carbon is acid washed in a 5.4-tonne vessel, stripped via high-temperature elution, and gold electrowon. Mercury captured in the retort is stored for disposal. For the sulphide refractory material, flotation will produce a saleable concentrate, reducing onsite waste and leveraging third-party processing infrastructure; no detailed flotation design criteria are provided in the section. Economically, the shared-crushing and phased processing approach (oxide first, then sulphide) minimizes initial capital while extending mine life. Sustainability initiatives include low-energy crushing (no milling), solution recycling, and liner systems that prevent groundwater contamination. Future outlook: once the oxide heap is depleted, the flotation plant will be constructed, and the crushing circuit will feed the sulphide bulk concentrate production. This dual-process strategy maximizes metal recovery (79.6% for oxide) and ensures the project can fully exploit the 108-million-tonne resource, positioning Q-Gold Resources for long-term gold production in southern Oregon.

Key Processes: Flotation, Heap Leaching, Cyanidation, Gravity Separation, Ball Mill, Crushing

Target Commodities: Gold, Silver