Traditionally an ore sample is crushed, ground and weighed before being heated and mixed with a flux containing in particular litharge (Pb oxide), a reducing agent (e.g. flour) and compounds forming a slag. The litharge is reduced into metallic Pb, which quantitatively extracts the precious metals. The fused mix is then poured in a mold where the lead containing the precious metals sinks to the bottom, while undesired impurities are moved into the slag floating on the top. After cooling down and removal of the slag the “cupellation” is performed, and the obtained button is heated in a “cupel” placed in an open furnace. The Pb is oxidized by the air and absorbed by the cupel, leaving only a precious metals bead. The bead is analyzed by various techniques, according to the purpose of the precious metals determination. Traditionally, the cupellation is expensive, environmentally unfriendly and labor-intensive. Instead, Optical Emission Spectroscopy (OES) can be used to measure the precious metals concentrations directly in the lead buttons, providing numerous advantages.
Benefits of the ARL Fire Assay Analyzer include:- Suppression of the cupellation simplifies and speeds the process to reduce costs on cupels, furnaces, power consumption, chemicals, laboratory equipments, etc.
- The environmental unfriendly and labor-intensive cupellation, sample preparation techniques and analyses are replaced by a simple and clean techniques
- High-quality results on all the precious metals, making it suitable even for the most demanding operations (e.g. plant control and metals accounting)
- All the precious metals in a sample analyzed simultaneously in about a minute
- Optimal availability for analysis through high stability and low maintenance
- Operators require only minimal training
- Possible automation of sample preparation and handling, ensuring high throughput and reliability of the analyses
- Factory calibrated to allow easy and rapid installation and commissioning
Important capabilities:
- Current Controlled Source (CCS) has the flexibility in selecting all parameters of the spark discharge: generation of very low currents permits highest sensitivity, excellent reproducibility and small dimensions on the limited size fire assay buttons
- Time Resolved Spectroscopy (TRS) system: set the appropriate time window for data acquisition when the signal to noise ratio is the most favorable, optimizing sensitivity and precision for trace analysis
- Paschen-Runge vacuum polychromator with a focal length of 1m, allowing excellent resolution
- Flexible and powerful OXSAS analytical software
- Special cast iron cabinet, temperature controlled to ±0.1° at 38°C
- Argon flushed, water-cooled table with self-contained, closed loop coolant system
- Ergonomically designed cabinet for rapid input of the sample and its identification
