Fire assay is a process used in the gold mining industry for use in the analysis of gold. Fire assaying utilises the mixture of oxidising and reducing reagents as well as extreme temperatures (in excess of 1000oC) to melt ores, and separate metals from other compounds such as silicates. The metals are then separated by further heating until only the precious metals remain e.g. gold, silver.

Due to such harsh temperatures being involved it can provide unnecessary risk if being performed by human hand.

Robotics and Automation can therefore provide capable and repeatable procedures for fire assaying. Robotic systems such as this one have much greater sample processing rates in comparison to the old way using human processing. Robots are not limited to set working hours, they do not experience much downtime, they have the ability to work 24 hours a day 7 days a week.

Technical Info: Detailed description of Chemistry Underlying Fire Assaying

Gold is determined in its ore, or metallurgic product, by obtaining a representative sample, through sample preparation, crushing, milling and grinding. Then weighing an adequately sized sample of this into a crucible and adding a mixture of reducing agent and flux and firing in a muffle furnace.

In the furnace the complete contents of the crucible are melted. The reducing/ oxidising agent acts upon the relevant compounds, the lead oxide is reduced to lead, which melts and collects the precious metals. The molten mass is then removed from the furnace and poured into a cone shaped mould and allowed to cool. The molten lead sinks to then bottom and carries any gold, silver, platinum and palladium with it. The other components of the ore along with the flux turn into a glassy slag which settles above the lead button. Upon cooling the lead button is separated from the glass. The button is placed into a bone ash cupel and the cupel is then placed into a furnace with a stream of air passing through it, turning the lead to lead oxide.

This melts and separates from the precious metals and mainly soaks into the cupel leaving a small bead of the precious metals, called a ?prill?. Also some of the lead oxide is volatilised. The prill that is recovered is removed and dissolved in aqua-regia. Generally the resulting solution is then analysed by Atomic Absorption Spectroscopy (AAS).

Robotics in the Laboratory:

Most analytical laboratories perform these analyses by hand which exposes staff to harmful environments and acids as well as repetitive boring work. However in recent years, developments in technology have arisen in the field of robotics and automation, and many labs are now converting their systems toward automation.

Laboratories around the globe are turning their sights to robotics and automation due to the ability to increase efficiency and reproducibility for sample analysis. Robots provide a means to deliver accurate, repeatable results with minimal time wastage as well as minimal materials wastage. Due to the ability of robots to be precisely programmed and their ability to follow complex algorithms, heating times and process times are able to be optimised according to requirements of specific samples.

Through the use of robots and simple automation, it is easy to perform many laboratory processes. Especially processes which mainly involve pick/place, dosing, weighing, heating, cooling, sample transfer and mixing actions, which covers most laboratory procedures.

For more information on how Argon Lab Systems will be suitable for your application contact us.??