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16th century cupellation furnaces (per Agricola). Cupellation is a refining process in metallurgy in which ores or alloyed metals are treated under very high temperatures and subjected to controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore.
Cementation crucibles, therefore, have a lid or cap which limits the amount of gas loss from the crucible. The crucible design is similar to the smelting and melting crucibles of the period utilizing the same material as the smelting and melting crucibles. The conical shape and smallmouth allowed the lid to be added.
Theophilus mentions the addition of urine to the mix. With heating, the silver reacts with the salt to form silver chloride which is removed leaving a purified gold behind. Conditions needed for this process are below 1000 °C as the gold should not melt. Silver can be recovered by smelting the debris. [20] Heating can take 24 hours.
When silicon is grown by the Czochralski method, the melt is contained in a silica crucible. During growth, the walls of the crucible dissolve into the melt and Czochralski silicon therefore contains oxygen at a typical concentration of 10 18 cm −3. Oxygen impurities can have beneficial or detrimental effects.
Slag can be classified as furnace slag, tapping slag or crucible slag depending on the mechanism of production. The slag has three functions. The first is to protect the melt from contamination. The second is to accept unwanted liquid and solid impurities. Finally, slag can help to control the supply of refining media to the melt.
Typically a transfer ladle will be used to transfer molten metal from a primary melting furnace to either a holding furnace or an auto-pour unit. Treatment ladle: a ladle used for a process to take place within the ladle to change some aspect of the molten metal. A typical example being to convert cast iron to ductile iron by the addition of ...
Crucible steel is steel made by melting pig iron , iron, and sometimes steel, often along with sand, glass, ashes, and other fluxes, in a crucible. Crucible steel was first developed in the middle of the 1st millennium BCE in Southern India and Sri Lanka using the wootz process. [1] [2] [3] [4]
Silver wires were made in Yemen by taking raw, unshaped silver (sabāyik in Arabic), [18] melting it in a crucible and then pouring the melted silver into a finger-length mold made from special earth shaped like a tube. [19] This produced ingots.
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