Gold Refining

How to Separate Silver & Gold by Cementation

Older processes explaining how to go about separating silver from gold by cementation were carried on practically in two ways, the first by heating gold for a long time with a mixture which evolved nitric acid on heating, and an absorbent into which any fusible salts ran; the mixture in the second method contained common salt … Read more

Sulphur Refining of Gold

Refining with Sulphur A more speedy method of removing iron, copper, lead and base metals from bullion is to add sulphur to the molten metals.  Although gold sulphides may be readily formed in the wet way, they are decomposed into gold and sulphur by merely heating them to a temperature below 300 deg. C. If … Read more

Refining Gold with Oxidizing and Chlorinating Agents

Nitre Refining When the molten gold is obviously impure nitre is added, and as a rule its main action is to eat the pot away, for as fast as metals are oxidised they are again reduced by the carbon of the pots. Where fireclay crucibles are used the nitre does effect a small amount of … Read more

Simple Methods of Gold Purification

The purification of such alluvial gold alloys is a simple matter. The high specific gravity of the metal allows of separation from most admixed materials by some process of elutriation, or water concentration, or, in arid regions, by dry blowing. The coarser particles are readily picked out, but the finer are usually admixed with heavy … Read more

How to Operate a Merrill Crowe Precipitation Process

Efficient Merrill Crowe precipitation of gold and silver is dependent upon the proper control of certain physical and chemical properties of the solution. The most important of these properties are listed below: SUSPENDED SOLIDS, such as ore slime and precipitates of calcium carbonate, with hydrates of aluminum, magnesium and iron, present in the pregnant solution … Read more

Gold Ore Chlorination

Experience has shown how difficult it is to obtain information regarding laboratory-tests in connection with the gold ore chlorination process for the extraction of gold from its ores, and I therefore present the following method, somewhat in detail, for the benefit of those who may desire to pursue research work in this field. The ore … Read more

Gold Smelting & Refining Process

Gold can be concentrated and recovered by applying different gold refining process methods and the final product has variable quality. In this way, it is necessary to have a better marketable product so that the incomes can be improved. Then, we have two smelt and cast the gold into bars called bullion or Dore. The … Read more

Gold & Silver Merrill-Crowe Zinc Precipitation Circuit Operation

In the Merrill-Crowe Zinc Precipitation, the pregnant solution tank collects the gold and silver bearing solution recovered from other circuits of the plant: thickener overflow; primary and secondary filtration? and the Argentite circuits. Normally these solutions contain very little solids content (15-100 ppm), however, even this small amount of solids is sufficient to inhibit efficient … Read more

Gold Chlorination Process by Miller

CHLORINATION PROCESS

Miller’s Gold Chlorination process was introduced by F.B. Miller.  The refining process employs chlorine gas, which passed into molten gold covered with a layer of borax and silica, and reacts with most of metals present in the molten charge. Platinum group metals do not react. Basically, gold is slightly attacked in the first moments and … Read more