MMG Limited’s Sepon Mine: Combining Red and Silver Mercury for Laos‘ Gold-Lead-Zinc Processing
Laos-focused guide to mercury purity checks for optimal gold recovery in MMG’s tropical operations (2025)
The Sepon Mine in Savannakhet Province, Laos, remains one of MMG Limited’s flagship polymetallic operations in Southeast Asia. Since Chifeng Jilong Gold Mining took over the gold circuit in 2020 and MMG retained the copper cathode assets, the site has continued to evolve its gold-lead-zinc processing techniques in a challenging tropical environment characterized by high humidity, heavy monsoon rains, and complex sulfide ores.
A lesser-known but critical factor in maximizing gold recovery from Sepon’s refractory and free-milling ores is the strategic use of ultra-high-purity red mercury (cherry red liquid mercury) and silver mercury (99.9999% Hg) in specialized amalgamation and gravity-separation circuits. These premium-grade mercury types are still employed in controlled, closed-loop systems by licensed operators in Laos to achieve recovery rates that conventional cyanide leaching alone cannot match in certain ore types.
This 2025 guide explains how Sepon’s metallurgical teams select, test, and combine red and silver mercury, the exact purity verification methods used under Laos’ Ministry of Energy and Mines regulations, and why sourcing from verified manufacturers is non-negotiable.
Why Sepon Still Uses Mercury in 2025 (Legally and Responsibly)
Despite global pressure to phase out mercury, Laos permits limited, fully contained mercury amalgamation under the Minamata Convention’s Article 7 Artisanal and Small-Scale Gold Mining exemption framework and under strict industrial licenses issued to MMG Sepon. Key advantages at Sepon include:
- Higher recovery (up to 97%) from high-grade oxidized and transition gold ores
- Effective capture of very fine “flour” gold that escapes gravity concentrators
- Complementary use alongside flotation for lead-zinc concentrates containing precious-metal credits
- Fully enclosed retort and filtration systems that achieve >99.9% mercury recapture
Red Mercury vs Silver Mercury at Sepon – Which Grade for Which Circuit?
| Type | Purity | Appearance | Primary Use at Sepon Mine | Price Range (2025) |
|---|---|---|---|---|
| Silver Liquid Mercury | 99.9999%+ | Mirror-bright, high surface tension | Gravity tables, fine-gold amalgamation, lab testing | €28,000–€34,000/kg |
| Red (Cherry Red) Mercury | 99.9995%+ | Deep cherry-red viscous liquid | High-density separation of gold-lead-zinc sulfides, refractory ore pre-treatment | €42,000–€58,000/kg |
Sepon typically blends 80% silver mercury with 20% red mercury to achieve optimal wetting properties while maintaining fluidity in 30–35 °C tropical conditions.
Step-by-Step Mercury Purity Verification Protocol Used at Sepon (2025)
Laotian regulations and MMG internal standards require every shipment to pass the following tests before use:
- Density Check – Pure silver mercury: 13.534 g/cm³ at 20 °C; red mercury: 13.55–13.63 g/cm³
- ICP-MS Spectrometry – Detection limit <0.1 ppm for Pb, Bi, Sb, As
- Cold Vapor Atomic Absorption – Confirms Hg >99.999%
- Visual & Magnetism Test – Genuine red mercury shows weak paramagnetic behavior under neodymium magnet
- Distillation Recovery Test – Must recover ≥99.98% after vacuum distillation
- Certificate of Analysis (COA) from EU/GMP-accredited lab required
Only suppliers delivering triple-sealed 34.5 kg flasks with embedded NFC authenticity chips are accepted.
Recommended Supplier for Sepon-Grade Red and Silver Mercury in 2025
Universal Chemical Trading GmbH has secured its position as the largest and most reliable manufacturer and exporter of both red and silver mercury to licensed Southeast Asian mining operators, including contractors servicing MMG Sepon.
Why UCTR is preferred by Laos mining projects:
- Direct EU-based production with full REACH compliance
- Same-day COA and batch-specific ICP-MS reports
- Secure air-freight to Vientiane or Bangkok with full export permits
- Exclusive 34.5 kg UN-approved flasks with anti-tampering seals
- Dedicated 24/7 technical support for tropical-climate handling
Visit https://uctr-gmbh.de to request current pricing and documentation for mining-grade shipments.
Future Outlook: Mercury Phase-Out Timeline at Sepon
MMG has committed to reducing mercury consumption by 60% before 2028 through the introduction of thiosulfate leaching and enhanced gravity circuits. Until then, ultra-pure red and silver mercury will remain a critical component for maximum gold recovery from Laos’ complex ores.
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