Fire Assay
Fire assaying is used to separate metals for the determination of impurities and quantity in a sample.
During this process the furnace will reach temperatures above 1000 degrees Celsius. The high temperature radiation and pernicious gas volatilization are extremely dangerous to the operators health. We provide a full range of fire assay tools which can reduce manual work intensity, improve work efficiency, safety and avoid high temperature radiation. All fire assay tools can be tailored for clients specific requirements.We provide a full range of fire assay tools which can reduce manual work intensity, improve work efficiency, safety and avoid high temperature radiation.
Features and Benefits
- Easy to maintain and operate
- Furnace compatible with “Multi-pour” loading / unloading system
- Furnace door panel for easy access to transformer.
- Furnace cabinet is durable 2mm laser cut plate, lined with high quality refractory bricks and insulation
- The furnace is mounted on a console fabricated from 2mm laser cut plate in blue enamel
Technical Specifications
| Application fields | Mining, metallurgy, and refining industries to accurately determine the precious metal content |
| Applications | separation of different materials, particularly minerals, by agitating a pulverized mixture of solids in liquids |
| Temperature Control | Electronic, automatic control maximum 1150°C/1200°C |
| Models | LM-25PFF, 25 pot fusion furnace LM-25PFF, 50 pot fusion furnace LM-50PCF, 25 pot cuppelation furnace LM-100PCF, 50 pot cuppelation furnace |
| Transformer | Fusion Furnace LM-20PF: 3ph, 15va Multi-tap Fusion Furnace LM-25PF: 3ph, 24va Multi-tap |
| Heating element | Fusion Furnace LM-20PF/LM-25PF: 12pcs, Silicon |
| Crucible quantity and size | Fusion Furnace LM-20PF: 20x50/65g - 30x30/40/55g Fusion Furnace LM-25PF: 25x50/65g - 30x30/40/55g |
| Avialible assisting tools | Hot pot trolley, pouring mould, pouring trolley with mould, workstation, slag plate, knock up up bench, pot trolley |
| Avialible work tools | Multi-pot pouring tong, Furnace shovel, Furnace brush, Furnace rake |
| Avialible storage tools | pot bench, crucible cooling, cupel cooling rack, tool rack |
| Electrical requirements | 0,55 kW |
| Power connection | 3 phase |
| Working area | Fusion Furnace LM-20PF: 560x480x190 Fusion Furnace LM-25PF: 560x590x195 LM-50PF: 450x250x145 LM-100PF: 560x480x190 |
| Dimensions (length x width x height) | Fusion Furnace LM-20PF: 1210x870x1760 Fusion Furnace LM-25PF: 1420x1120x1930 Cupellation Furnace LM-50PF: 1100x1100x1700 Cupellation FurnaceLM-100PF: 1210x970x1760 |
Working principle
Fire assay is a highly precise and traditional method used to determine the content of precious metals, such as gold, silver, and platinum, in ore samples. This method, which dates back thousands of years, is considered the most accurate for quantifying these metals. The process involves several key steps and the use of various specialized tools and materials:
A representative sample of the material is taken and ground into a fine powder.
The powdered sample is mixed with fluxes (usually a combination of lead oxide, borax, soda ash, and silica) and a reducing agent.
This mixture is placed in a crucible and heated in a furnace to temperatures typically between 1,000°C and 1,200°C (1,832°F to 2,192°F).
The high temperature causes the lead oxide to be reduced to metallic lead, which collects the precious metals from the sample.
The lead and precious metals form a lead button at the bottom of the crucible, while the remaining materials form a slag that floats on top.
The lead button is separated from the slag.
The lead button is placed in a cupel (a porous container) and heated in a cupellation furnace.
The lead oxidizes and is absorbed by the cupel, leaving behind a bead of precious metal.
The precious metal bead is weighed to determine the content of gold, silver, or other precious metals.
For more precise analysis, further techniques like gravimetric analysis or spectrometry may be used.
Fire Assay equipment
Crucibles:
Containers made of heat-resistant materials used to hold the sample and flux mixture during the fusion process.
Furnaces:
High-temperature furnaces are used for both the fusion and cupellation steps.
Fluxes:
Chemical substances (lead oxide, borax, soda ash, silica) that aid in the melting of the sample and the collection of precious metals.
Cupels:
Porous containers, often made of bone ash or magnesium oxide, used to absorb lead during cupellation.
Balances:
Highly precise analytical balances for weighing the precious metal bead.
Tongs and Safety Equipment:
Tools for handling hot crucibles and cupels, as well as protective gear for the operator (gloves, safety glasses, lab coat).
Molds:
Used to pour and cool molten materials during the fusion process.
Assay Lab Equipment:
Additional equipment such as ovens for drying samples, sieves for powdering samples, and storage containers for reagents and samples.
Fire assay is a complex process requiring skilled technicians to perform accurately, but it remains the gold standard in the industry for precious metal analysis due to its reliability and precision.
Fire Assay FAQ (Frequently Asked Questions)
Applications
Fire assay is one of the most accurate methods for determining gold and silver content in ore and concentrates.
Used to evaluate the gold and silver content in raw material and waste during exploration and mining operations.
- It can be used to test materials for trace metals, often in soil or water samples, as part of environmental assessments and compliance testing.
- Used to quantify the amount of precious metals in scrap materials, such as jewelry, electronics, or catalytic converters.
- In metal refining operations, fire assay helps determine the purity of precious metals and allows refiners to assess the quality and quantity of their product before final purification processes.
- It's crucial for creating certified reference materials for calibration of other assay methods or for validating assay results in industry-standard testing.
- Employed by geologists for evaluating rock samples to estimate potential for economic extraction of metals in exploration projects.
- Can be used to determine metal content in ancient artifacts or in archaeological sites, offering insights into past human activities.