In this study, experiments were conducted to understand the effects of
different quantities of additional iron and oxidizing flux (Na2O2) on the
direct fire assay of low grade pyritic refractory gold ores instead of
performing any pre-treatment like roasting before fire assay. A portion of
the pyritic ore was primarily roasted using a rotary kiln to remove sulphur
content for the comparison of the results obtained from direct fire assay of
the pyritic ore. Then, fire assay process was performed to the roasted ore
and gold and silver content in the ore was determined. Unroasted ore
specimens were fused by using fluxes and PbO, which accumulates the precious
metals, with various quantities of iron. Correlation between the quantity of
additional iron and the recovery of gold-silver were investigated. Various
quantities of Na2O2, as an oxidizing flux, were added to the smelting charge
with iron additions, from which the highest gold and silver recoveries were
obtained from previous experiments. From the results, it was clear that the
increase in additional iron and Na2O2 quantities was the reason for the
increase in the recovered amounts of lead, gold and silver during the
process.
The effect of iron and oxidizing flux addition on the fire assay of low grade pyritic refractory gold ores
