Gold Fire Assay Process
The Gold Fire Assay Process of ores is almost universally conducted in the dry procedure by furnace methods. Exceptions will be noted later. The plan of operation is to concentrate the precious metal in a button of lead either (1) Fire Assay By fusion in a crucible; or, more rarely, (2) Fire Assay By scorification. […]
Fire Assay Flux & Litharge Composition
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 […]
Gold Inquartation Process
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 […]
Cupellation Furnace
Cupellation is conducted in a muffle furnace, the construction of which is shown in Figs. 62-63. The fire is lighted, a little bone-ash is sprinkled on the floor of the muffle to prevent its corrosion by litharge in case of the upsetting of a cupel, and the cupels introduced as soon as a bright red […]
Precious Metals Refinery Security
“Highgrading” a polite word for stealing gold and silver for your refinery, has been a way of life since the metals in native form have been mined or produced. Unfortunately, in the past, highgraders were not always severely prosecuted or even looked upon unfavorably in their communities. Recent high metal prices with attendant world wide […]
Merrill Crowe Leach Solution Sampler
This keeps the leach sample secure prior to its assaying. A simple electric box, lock and key, piece of pipe, funnel, bottle and yes, some wire.
Alkali Consumption Tests
It is often desirable to ascertain by preliminary experiments the quantity of alkali which will be needed to neutralize acidity in any particular ore. In this connection a distinction is sometimes made between “ free ” and “ latent ” acidity. The free acidity is that due to substances soluble in water, and is determined […]
Organic Carbon TOC Pre-Flotation & Preg‐Robbing of Gold
Organic carbon is a common problem for base metal production and precious metal leaching. In froth flotation, liberated organic carbon is naturally hydrophobic and will be recovered with the other minerals, lowering the grade of the concentrates. It can also adsorb collectors and frothers, reducing the efficiency of the mineral recovery process. In leaching, the […]
Fire Assaying; a Miniature Smelting Process
Fire assaying, in essence, is a miniature or small scale smelting process which recovers and reports the total gold content of the assay sample, including gold combined with other elements or locked in the ore particles. Because of this, a assay may report values that cannot be recovered by placer methods and it cannot be […]
Gold Refining Process by Aqua Regia
The Gold Refining Process by Aqua Regia was introduced at the Pretoria Mint after the Miller process had been tried and abandoned owing to the alleged difficulty of treating the gold bullion extracted by the cyanide process. In the aqua regia process the gold is dissolved and precipitated. It is made very difficult if the […]