After the assayer has tested the ore and measured how much silver it contains, he reports his findings to the workers who operate the great melting furnaces. These workers depend greatly on his judgment. His report helps them decide how much of each material must be added to the ore so that it melts properly and produces the best amount of silver. Without this careful report, the melting process would be uncertain and wasteful A Famous Place of Natural Hot Baths.
The workers do not treat all ore in the same way. Instead, they change the mixture based on the richness and nature of the ore. For example, if they have one hundred centen, or about ten thousand pounds, of silver ore that contains more than two and a half ounces of silver in every hundred pounds, they prepare a special mixture to improve the melting.
Materials Mixed with the Ore
To this large quantity of ore, they add about forty centen of “Letch,” which is ore that has already been pounded and washed. This helps the melting process by improving the flow of the material in the furnace. They also add around two hundred centen of iron-stone. This iron-stone is not true iron ore but a special kind of stone found in the nearby hills. The miners say that the liver-colored variety is the best and most useful for their work.
In addition, they include a quantity of “Kis,” which is a kind of pyrites. The amount of this material depends on how much marcasite is mixed with the ore. If the ore contains more marcasite, then more Kis is added to balance the mixture. Another substance they add is called “Slacken.” This is the scum or crust that forms on the surface of melted metals in the pan. It is collected during earlier smelting and reused. Slacken is created from the fusion of the different materials used in the furnace and can help control the melting process Private Turkey Tours .
The Process of Melting in the Furnace
Once all the materials are properly mixed, they are placed inside the melting furnace. When the mixture melts, the liquid metal flows out through a hole at the bottom of the furnace. It then runs into a large pan that is set into the ground in front of the furnace. As soon as the melted substance is exposed to the air, a hard crust or scum quickly forms on the surface.
This crust, also called dross or cake, must be removed again and again. Workers carefully take it off from the top while the metal continues to melt and settle below. By constantly removing this scum, the remaining metal becomes purer and cleaner.
The Use of Lead in Separating Silver
During this stage, lead is added to the melted mixture. Lead plays a very important role in the process. It attracts and gathers the silver, carrying it down to the bottom of the pan. Over time, the silver and lead settle together, forming a heavier mass separate from the waste materials.
After enough time has passed, the melted metal is taken out and moved to another furnace called the driving furnace. This second furnace is used to refine the metal even further.
Refining the Silver in the Driving Furnace
In the driving furnace, the mixture of silver and lead is heated once again. Two large bellows blow strong air into the fire, making the heat more intense. This strong heat causes the lead and other remaining impurities to separate from the silver.
As the impurities melt and burn away, they flow off in the form of litharge. The litharge that first comes off is white in color because it has been exposed to the fire for a shorter time. Later, the litharge becomes red, as it remains longer in the intense heat of the furnace. However, both the white and red litharge come from the same metal and are not different metals. Through this careful process of melting, skimming, and refining, the workers are able to produce purer silver from the original ore.