The following remarks on the use of the fire assay fluxes and litharge may serve as an aid in arriving to a correct composition of charges for most cases: Litharge or red lead is added in the proportion of one or two parts to two of ore; if too much litharge (lead oxide) is used the … Read more
The object of the Fire Assay Fusion is to concentrate the precious metals in a button of lead, while the whole of the remainder of the ore forms a fusible slag with suitable fluxes, in which lead sinks. The fusion is made in clay (or rarely iron) crucibles in a wind furnace, similar to, but usually … Read more
The bead of silver and gold obtained by cupellation is squeezed between pliers, or flattened by a hammer on a clean anvil, to loosen the bone ash adhering to its lower surface, and is then cleaned by a brush of wires or stiff bristles. It is then weighed, the silver removed by solution in nitric … Read more
Listed and explained in details below are 8 Gold Assay Methods which are alternatives to the classic fire assay method. Amalgamation Assay This is useful in determining the amount of gold present in the ore capable of being extracted by mercury. The sample of ore is pulverised fine enough to pass through a 60- or 80-mesh … Read more
How to detect gold in loose alluvial ground has been already described. A similar method may be employed in the case of auriferous quartz after grinding it. If the concentrates obtained in either case contain sulphides, these are collected, roasted or treated by nitric acid and re-ground. The light particles of oxide of iron can now … Read more
As stated above, the Scorification Assay process is especially applicable to (a) complex ores, (b) very rich ores, (c) ores which are mainly valuable for their silver contents. The losses are small and the operations are easy to conduct, and need not be varied much for different classes of ore. For these reasons the process … Read more
To determine the amount of gold metal in ore, there are two kinds of gold assay adopted: The dry assaying method (i.e. by fusing the powdered ore with or without fluxes). The wet assaying method (i.e. by the agency of liquids). In the principal wet assay, the ore is thoroughly dissolved in acids, and, by … Read more