Smelting process for silver and gold precipitate in Induction Furnace

Smelting gold and silver is an important procedure. Once gold and silver precipitate is smelted, gold and silver ingots can be recovered. These Silver and gold ore – precipitate (concentrate) is the product of Merrill-Crowe process or other similar process. The smelting process involves the use of an induction smelting furnace.

Let’s look at the steps involved in the gold and silver smelting process:

Preparing Flux

The first step involves a chemical called flux. The most common form of flux used in gold and silver smelting is Borax, Sodium Nitrate and Silica. The percentage of these fluxes varies and It depends on the composition of the precipitate. These fluxes are mixed with gold and silver concentrate. Using flux is necessary as it brings the impurities to the surface. The gold and silver settles down and can easily be removed. This is a simple but tedious process.

Melting Gold and Flux in Induction Furnace

When the mixture of gold and flux are placed in the induction furnace, both materials melt in the furnace. The furnace is heated to high temperatures exceeding 900°C. It takes a while for the entire mixture to liquefy. After the mixture melts, the precious metals and impurities separate. This is the aim of the entire procedure. Gold and silver are denser than most impurities in it. This allows the gold and silver to settle down. The flux and other impurities rise to the surface.

Separating Gold and Silver from Flux

In the smelting process, the most important aspect is separating the impurities and flux from the gold and silver. Gold and silver normally settles towards the bottom of the furnace. This makes it easy to drain the impurities that have risen to the top. Carefully, the impurities are drained from the furnace. This leaves gold and silver at the bottom of the furnace. Once the purified gold and silver are left in the furnace, it can be poured into molds. When pouring the precious metals into a mold, metal test sample can be taken using vacuum tube.

These gold and silver ingots are not in pure gold and silver form. They contain other metals like Copper, Lead, Zinc and Fe. Percentages of these metals are less in comparison to gold and silver. These ingots will send to refinery for further purification.