Lead Fire Assay Is Divided Into Three Phases

(1) melting. It is by means of solid reagent and rock, ore or metallurgical products were mixed and heated in a crucible of molten, with lead capture gold and silver and precious metals in the molten state, forming a lead alloy (generally referred to as lead button, also known as your lead), Because significant than lead alloys, sink to the bottom of the crucible. At the same time, the sample base metal oxides and gangue and silica, borax, sodium carbonate flux combination reaction occurs, generating slag silicate or borate, because the proportion of small and float on top, whereby the silver is separated from the sample. Therefore, in the fire assay process, while samples from the decomposition of the two precious metals and enrichment effect.

(2) ash blown. The lead alloy was placed gray dish at an appropriate temperature with were ash blowing lead, when cupellation lead oxide into lead oxide and the penetration in porous gray dish to remove the lead button of lead and small amounts of base metals, gold silver and precious metals from oxidation protection and remain in the ash pan fit into the form of gold and silver grains.

(3) sub-payment. Together with nitric acid to dissolve gold and silver tablets, the silver is dissolved, while gold remained solid, gold particles obtained after quenching weighing, calculate the gold content, can be calculated based on the difference between gold and silver content of the silver and gold combined mass of grain quality .

After completion of fire assaying method Separation and enrichment of gold and silver and precious metals, in addition to the above determination of gold, silver gravimetric method, gold and silver will be dissolved with aqua regia close grain, can be used a variety of chemical analysis method for the determination of gold, silver and other precious metals .