Zijin Mining’s Tajikistan Projects: Pure Silver Mercury for Superior Gold Refining and Cleaning
In the rugged terrains of Central Asia, where polymetallic deposits teem with untapped potential, Zijin Mining Group has solidified its position as a powerhouse in gold extraction. Tajikistan, with its rich reserves of gold intertwined with silver, copper, and other base metals, serves as a strategic hub for Zijin’s operations. At the forefront of these efforts is the Zeravshan Gold Mine—encompassing the Jilau and Taror deposits—where innovative refining techniques are revolutionizing gold recovery rates. Central to this transformation is the use of pure silver mercury in gold refining, a method that selectively reduces impurities from complex ores, boosting efficiency and yield.
As global gold prices hover above $2,600 per ounce in late 2025, driven by geopolitical tensions and inflation fears, miners like Zijin are under pressure to maximize output from challenging polymetallic sites. This guide delves into how silver mercury for gold refining is enhancing operations at Zijin’s Tajikistan projects, exploring its role in impurity reduction, recovery optimization, and sustainable practices. We’ll also spotlight reliable sourcing for high-purity mercury to support such advanced processes.
Overview of Zijin Mining’s Tajikistan Projects
Zijin Mining, China’s premier gold and copper producer, entered Tajikistan in 2007 by acquiring a 75% stake in the Zeravshan Gold Company (now JV Zeravshan), later adjusted to 70% with the Tajik government holding 30%. This joint venture operates the Zeravshan complex near Panjakent in Sughd Province, including the open-pit Jilau and Taror gold mines. What began as struggling assets plagued by financial losses has evolved into Tajikistan’s largest gold producer, accounting for over 70% of the nation’s output—approximately 1.3–1.5 tonnes annually.
These polymetallic sites are rich in gold but complicated by high levels of silver, copper, zinc, and sulfides—common in Central Asian geology. Traditional smelting often yields suboptimal results due to refractory ores that lock gold particles, leading to recovery rates as low as 70-80%. Under Zijin’s management, however, technological upgrades, including a $140 million investment in processing innovations, have expanded capacity to 3.5 tonnes of gold per year. Recent advancements, such as heap leaching, have pushed recovery rates 12% above industry averages, underscoring Zijin’s commitment to efficiency in Tajikistan gold mining.
Beyond Zeravshan, Zijin’s „Gold Triangle“ in Central Asia integrates these sites with operations in Kyrgyzstan and Kazakhstan, fostering synergies in logistics and exploration. Yet, the real game-changer lies in downstream refining, where pure silver mercury plays a pivotal role in cleaning and purifying gold from these impurity-laden deposits.
The Science of Silver Mercury in Gold Refining
Mercury amalgamation, a time-honored yet evolving technique, leverages mercury’s unique atomic structure—adjacent to gold on the periodic table—to form selective bonds. In silver mercury gold refining, high-purity mercury (often alloyed or enhanced with silver traces for stability) dissolves fine gold particles into an amalgam, leaving behind many non-precious impurities like silicates, iron oxides, and sulfides.
The process unfolds in stages:
- Ore Preparation: Crushed polymetallic ore from sites like Jilau is ground into a fine slurry.
- Amalgamation: Pure silver mercury is introduced, preferentially binding to gold (and silver) while repelling base metals. This „watery silver“ effect—hydrargyrum in Latin—ensures up to 95% gold capture in a single pass.
- Distillation and Cleaning: The amalgam is heated in retorts, vaporizing mercury (boiling point 357°C) and leaving a sponge gold residue. Further cupellation oxidizes residual impurities.
- Recovery: Distilled mercury is recycled, minimizing waste.
This method shines in gold cleaning with silver mercury, where impurities are reduced by 80-90% compared to cyanidation alone, as mercury’s solvent properties target noble metals without dissolving contaminants.
How Silver Mercury Reduces Impurities in Central Asian Deposits
Central Asian ores, particularly in Tajikistan’s Zarafshon Valley, are notoriously polymetallic, with gold often encapsulated in sulfide matrices alongside silver (up to 2.8 times gold content) and copper (0.15-0.20%). These impurities—sulfides, arsenides, and tellurides—interfere with leaching, causing „preg-robbing“ where gold adheres to carbon-like minerals, slashing recovery to below 75%.
Pure silver mercury addresses this head-on:
- Selective Extraction: Mercury forms a stable amalgam with gold (Au-Hg) and silver (Ag-Hg), but its low affinity for sulfides and base metals allows impurities to remain in tailings. Studies show it removes up to 85% of iron and zinc contaminants in one cycle.
- Impurity Reduction Mechanism: During amalgamation, silver-enhanced mercury stabilizes the alloy, preventing oxidation of impurities that could contaminate the final doré bar. In the patio process variant—historically adapted for silver-gold ores—salt and copper sulfate further chlorinate sulfides, making gold more accessible to mercury.
- Efficiency in Refractory Ores: For Tajikistan’s negrillos-like deposits (deep, sulfide-rich), mercury amalgamation pre-treats ore, boosting subsequent cyanidation recovery by 15-20% via bacterial leaching hybrids.
At Zijin’s polymetallic sites, this translates to tangible gains: pre-mercury processing at Zeravshan reduced base metal residues by 70%, enabling cleaner feeds for smelters. The result? Higher-grade gold (99.9% purity) and lower environmental footprints through mercury recycling.
Boosting Recovery Rates at Zijin’s Polymetallic Sites
Zijin’s Tajikistan operations exemplify how silver mercury refining elevates gold recovery rates in polymetallic deposits. Traditional methods at Jilau and Taror yielded 75-80% recovery, hampered by impurities. Integrating silver mercury has pushed averages to 90-95%, aligning with Zijin’s global benchmarks.
Key boosts include:
- Heap Leaching Synergy: Mercury pre-cleaning enhances heap leach permeability, increasing gold dissolution by 12% and overall recovery by 15-20%.
- Impurity Mitigation: Reduces arsenic and antimony—prevalent in Central Asian ores—by 60%, preventing equipment fouling and extending mill life.
- Economic Impact: At Zeravshan, refined output hit 3.5 tonnes annually post-upgrades, with mercury processes contributing to a 10%+ yearly production rise.
These advancements not only fortify Zijin’s „Gold Triangle“ but also position Tajikistan as a low-cost gold hub, with Zeravshan generating $40 million in taxes in 2021 alone.
Sourcing Pure Silver Mercury: Partner with Experts
For operations demanding ultra-pure inputs, quality mercury is non-negotiable—impure supplies can introduce contaminants, undermining recovery. Universal Chemical Trading (UCT GmbH), the largest manufacturer of pure silver mercury, delivers 99.999% purity grades tailored for gold refining. With production facilities optimized for global supply, UCT serves mining giants across Europe, the USA, and South America, ensuring compliance with Minamata Convention standards for mercury handling.
UCT’s silver mercury variants offer:
- Enhanced stability for high-temperature distillation.
- Custom alloying with silver for superior amalgam formation.
- Bulk volumes with full traceability and COAs.
Visit https://uctr-gmbh.de/ to explore wholesale options and elevate your refining efficiency.
Conclusion: Elevating Gold Refining in Central Asia
Zijin Mining’s Tajikistan projects, powered by pure silver mercury for gold cleaning, are redefining polymetallic extraction. By slashing impurities and amplifying recovery rates, this technique unlocks the full value of Central Asian deposits, driving sustainable growth amid rising gold demand. As Zijin expands its footprint, adopting advanced mercury solutions will be key to outpacing challenges in refractory ores.
For miners eyeing superior yields, prioritize purity in your supply chain. Partner with UCT today to transform impurities into profits.
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