Overcoming Extreme Cold and Low-Grade Ore: Two High-Performance Gold Heap Leach Projects in Mongolia

Mongolia’s harsh mining landscape, low-grade deposits, and prolonged sub-zero temperatures have historically been viewed as major barriers to economic gold production. We challenged that assumption head-on. Xinhai successfully designed, built, and brought into stable commercial operation two large-scale heap-leach gold projects: one at 1.2 million t/a(commissioned in 2018) and a significantly larger 3.0 million t/a facility (first gold in late 2022). These are not demonstration plants — they are full-scale, revenue-generating operations running reliably today at grades as low as ~0.7 g/t and in ambient temperatures down to −35 °C. Key results speak for themselves:

• 1.2 Mt/a project — consistent ~80% gold recovery from 1.45–1.6 g/t ore

• 3.0 Mt/a project — steady-state operation delivering ~60% recovery from actual run-of-mine grades averaging ~0.7 g/t under severe winter conditions

Both assets continue to perform well, proving heap leaching can be technically robust, operationally dependable, and economically compelling even in the world’s most demanding cold-climate, low-grade settings.

011.2 Mt/a Gold Heap Leach Plant – Making Low-Grade Work

This project was developed for a sophisticated Australian mining investment company with exacting standards for technical rigor and execution certainty. Early in the study phase, we conducted detailed comparative test work on CIL versus heap leach using representative ore samples.

The outcome was unequivocal: both processes could achieve approximately 80% gold recovery from the 1.45–1.6 g/t feed. When capital efficiency, operational simplicity, maintenance demands, and long-term cost control were taken into account, heap leaching clearly offered the better overall value proposition — matching recovery performance while materially reducing upfront and operating expenditure.

We then delivered a fully engineered, fit-for-purpose heap leach circuit:

• 5,000 t/d primary & secondary crushing circuit sized for continuous stacking

• Dual heap leach pads with cross-leaching configuration and single-lift stacking (150,000 tonnes per heap)

• 8-month operating season comprising eight complete leach cycles (~60 days per cycle)

• Efficient post-leach waste removal and on-pad heap re-stacking to maximize pad life and land use

Leveraging our proven ADR technology, we progressed from contract award through detailed design to delivery of critical refining equipment in only seven months — significantly accelerating the client’s path to production.

Outcome: clear validation that heap leaching is fully bankable and highly competitive at grades around 1.5 g/t.

023.0 Million t/a Heap Leach Project — Year-Round Operation at −35 °C.

This large-scale project tested the limits: design feed grade ~1.0 g/t (actual average ~0.7 g/t), winter lows reaching −35 °C, and a site topography with natural 5–6% slopes.

We took full ownership of the process plant design and supply outside the primary crushing area — delivering heap leach pads, a complete ADR circuit, water management systems, power distribution, civil & structural works, overall site layout, and essential heating & ventilation infrastructure.

Our guiding objective from day one of engineering was uncompromising: continuous, all-season operation. We engineered the heap leach system — from solution application and collection to insulation and freeze-protection measures — to eliminate the seasonal downtime that had long constrained cold-climate heap leaching.

The equipment arrived at the site in April 2022. Working closely with the owner’s construction team using our detailed installation packages and field support, the plant was commissioned and was producing by the end of 2022. Despite some ore variability and site-specific challenges, the operation has stabilized and is now firmly in a profitable growth trajectory.

Technical Specifications & Process Flow

This project provides definitive proof: heap leaching remains technically sound and commercially viable at grades as low as 0.7 g/t — even in sustained −35 °C conditions.

03Extending the Operating Envelope for Gold Projects

These two Mongolian projects are powerful examples of what Xinhai brings to the table: deep process know-how, pragmatic engineering tailored to site realities, relentless focus on execution speed and operational certainty, and an unwavering commitment to client outcomes.

We thrive on turning difficult resources into producing assets — especially where others see only obstacles.

If you’re evaluating a low-grade or cold-climate gold project and want a partner that has already delivered results in exactly those conditions, we’re ready to talk.

Let’s turn your next challenge into production success.

Reach out — we’d welcome the opportunity to discuss how we can add value to your project.