Silver Mercury (Elemental Mercury): Comprehensive Guide to Properties Applications and Compliance
May 09,2026
Author: Industrial Chemicals & Hazardous Materials Specialist | Updated: May 2026 | Verified by ISO 9001 Certified Laboratories & Regulatory Experts
Executive Summary
Silver Mercury (commonly referred to as liquid silver mercury, quicksilver, or elemental mercury, chemical symbol Hg) is a unique transition metal that exists as a dense, silvery-white liquid at room temperature. With a CAS Number 7439-97-6 and EINECS 231-106-7, it is defined by exceptional physical properties including high density, thermal conductivity, and uniform volumetric expansion. This article provides an authoritative, EEAT-compliant analysis of silver mercury's technical specifications, industrial production, key applications, stringent safety protocols, and global regulatory compliance, essential for manufacturers, importers, and industrial users.
1. Chemical & Physical Properties
Silver mercury is elemental (metallic) mercury, a pure chemical element distinct from organic or inorganic mercury compounds.
Core Physical & Chemical Characteristics
表格
| Parameter | Standard Specification (Prime Virgin Grade) | Test Method |
|---|---|---|
Chemical Formula | Hg | — |
Molecular Weight | 200.61 g/mol | — |
Appearance | Silvery-white, mirror-like liquid, free of impurities | Visual Inspection |
Density (20°C) | 13.53 g/cm³ (13.59 at 4°C) | Hydrometer |
Melting Point | -38.87°C | Differential Scanning Calorimetry |
Boiling Point | 357.55°C | Distillation Test |
Vapor Pressure (25°C) | 0.002 mm Hg | Manometric Method |
Coefficient of Thermal Expansion | 181.7 × 10⁻⁶ /°C (20°C) | Dilatometry |
Solubility | Insoluble in water & dilute acids; soluble in HNO₃, aqua regia, hot concentrated H₂SO₄ | Dissolution Test |
Purity (Prime Grade) | 99.999% (5N) | ICP-MS Analysis |
Total Impurities | ≤ 0.001% | Gravimetric Analysis |
Iron (Fe) | ≤ 0.0002% | Atomic Absorption |
Other Heavy Metals (as Pb) | ≤ 0.0004% | ICP-OES |
Key Properties Defining Its Utility
- Liquid State at Ambient Conditions: The only metal liquid at standard temperature and pressure (STP).
- High Density & Conductivity: Exceptional thermal and electrical conductivity for precision applications.
- Uniform Thermal Expansion: Predictable volume change with temperature, critical for measurement devices.
- Amalgamation: Forms amalgams (alloys) with gold, silver, zinc, and aluminum, but not iron.
- Volatility: Evaporates slowly at room temperature, producing toxic, odorless vapor.
2. Industrial Production & Refining Process
High-purity silver mercury (99.999%) is produced via a controlled, environmentally sealed process:
2.1 Primary Extraction (from Cinnabar Ore)
- Mining & Roasting: The ore cinnabar (HgS) is roasted in air:
- \(\text{HgS} + \text{O}_2 \rightarrow \text{Hg} \uparrow + \text{SO}_2 \uparrow\)
- Vapor Condensation: Mercury vapor is condensed and collected as crude liquid.
2.2 Multi-Stage Refining (for 99.999% Purity)
- Vacuum Distillation: Impurities (base metals, sulfur) are removed under high vacuum.
- Electrorefining: Electrochemical purification eliminates trace heavy metals.
- Filtration: Passed through microporous filters to remove particulate contamination.
- Quality Verification: Analyzed via ICP-MS to confirm 5N purity compliance with GB913-85 (China) and ASTM D4222 standards.
2.3 Environmental Controls
- Emission Capture: HEPA & activated carbon filters trap >99.9% of mercury vapor.
- Waste Treatment: Wastewater treated to meet 40 CFR Part 421 (US) and HJ 931-2017 (China) limits中华人民共和国生态环境部.
- Closed-Loop Systems: Zero-discharge manufacturing to prevent environmental release.
3. Primary Industrial Applications
Silver mercury is a critical raw material in high-precision industries, despite regulatory restrictions:
3.1 Gold & Precious Metals Mining (Largest Application)
- Amalgamation Process: Selectively binds with gold to form gold-mercury amalgam, separating it from ore.
- Efficiency: Enables recovery of fine gold particles inaccessible to other methods.
3.2 Scientific & Industrial Instruments
- Thermometers & Barometers: Utilizes uniform thermal expansion for precision measurement.
- Mercury Switches & Relays: For high-voltage, heavy-duty electrical control systems.
- Vacuum Pumps & Manometers: Reliable operation in high-vacuum systems.
3.3 Lighting & Electrical Industry
- Fluorescent & High-Pressure Lamps: Generates UV radiation to excite phosphors.
- Mercury Vapor Rectifiers: Converts AC to DC in industrial power systems.
3.4 Chemical & Electroplating Industry
- Catalyst: In organic synthesis and chlor-alkali processes (restricted).
- Electroplating: For specialized mirror coatings and reflective surfaces.
4. Safety, Handling & Toxicology
Silver mercury is classified as a Category 3 Acute Toxic (inhalation) and Category 1 Chronic Toxic substance under GHS/CLP (EC 1272/2008).
4.1 Health Hazards
- Inhalation (Primary Risk): Vapor absorption causes neurological damage (tremors, memory loss, irritability), kidney failure, and respiratory failure.
- Skin Contact: Poor absorption through intact skin but causes irritation; severe exposure via cuts.
- Ingestion: Rare but leads to systemic poisoning and organ damage.
4.2 Safe Handling Protocols
- PPE: Butyl rubber gloves, face shield, mercury-vapor respirator, and impermeable apron.
- Engineering Controls: Work in fume hoods or sealed, ventilated enclosures with continuous vapor monitoring.
- Spill Response: Immediately cover spills with sulfur powder to form non-volatile HgS.
- Storage: Seal in airtight steel cylinders (34.5 kg) or iron flasks in cool, dry, segregated areas.
4.3 Shelf Life & Packaging
- Shelf Life: 24 months when properly sealed and stored.
- Packaging: UN-approved steel drums (34.5 kg net) or 1 kg amber glass bottles.
- Labeling: Must display UN 2809, hazard statements (H330, H373, H410), and GHS symbols.
5. Global Regulatory Compliance
Silver mercury is among the most heavily regulated industrial chemicals due to the Minamata Convention on Mercury (2013).
5.1 International Regulations
- Minamata Convention: Bans new mercury mining, phases out non-essential uses, and mandates export controls.
- UN Recommendations: Classified as Class 8 (Corrosive) & Class 6.1 (Toxic) for transport; UN Number 2809.
5.2 Regional Compliance
- EU: Regulation 2017/852 restricts use; REACH lists as SVHC; RoHS limits in electronics.
- US: EPA 40 CFR Parts 61 & 421 controls emissions and effluents.
- China: GB913-85 quality standard; Ministry of Ecology and Environment HJ 931-2017 for emissions中华人民共和国生态环境部.
5.3 Trade & Export Requirements
- Export License: Mandatory in most countries.
- End-User Declaration: Proof of legitimate industrial use (e.g., mining, electronics).
- Dangerous Goods Documentation: MSDS (16-section), transport declaration, and packaging certificates.
6. Quality Standards & Grades
Silver mercury is supplied in three primary grades:
- Prime Virgin Grade (99.999%): For gold mining, high-precision instruments, and electronics.
- Technical Grade (99.9%): For industrial lighting and non-critical applications.
- Lab Grade (99.99%): For analytical chemistry and research.
Conclusion
Silver Mercury (Elemental Mercury) remains an irreplaceable material for gold mining, precision instrumentation, and specialized industrial processes, valued for its unparalleled liquid metallic properties. Its use demands strict adherence to safety protocols and global regulations to protect human health and the environment. For industrial buyers, sourcing 99.999% pure silver mercury from Minamata-compliant, ISO-certified suppliers is critical to ensure quality, legality, and responsible stewardship of this high-priority hazardous material.
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