Search results
Results from the WOW.Com Content Network
Smelting involves more than just melting the metal out of its ore. Most ores are the chemical compound of the metal and other elements, such as oxygen (as an oxide), sulfur (as a sulfide), or carbon and oxygen together (as a carbonate). To extract the metal, workers must make these compounds undergo a chemical reaction.
The flux lowers the melting point of the desired compound, analogous to a wet chemistry recrystallization. [1] The flux is molten in a highly stable crucible that does not react with the flux. Metal crucibles, such as platinum , titanium , and niobium are used for the growth of oxide crystals.
Vacuum induction melting (VIM) utilizes electric currents to melt metal within a vacuum. The first prototype was developed in 1920. [1] Induction heating induces eddy currents within conductors. Eddy currents create heating effects to melt the metal. [2] Vacuum induction melting has been used in both the aerospace and nuclear industries. [2]
The advantage of the induction furnace is a clean, energy-efficient and well-controlled melting process, compared to most other means of metal melting. Most modern foundries use this type of furnace, and many iron foundries are replacing cupola furnaces with induction furnaces to melt cast iron, as the former emit much dust and other pollutants ...
Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a joining of the metals. It is a type of welding that uses a welding power supply to create an electric arc between a metal stick (" electrode ") and the base material to melt ...
In one of the previous melting stages, lead was added. Gold and silver preferentially dissolved in this, thus providing a means of recovering these precious metals. To produce purer copper suitable for making copper plates or hollow-ware, further melting processes were undertaken, using charcoal as fuel. The repeated application of such fire ...
When the metal level is sufficiently high, the cupola tender opens the "tap hole" to let the metal flow into a ladle or other container to hold the molten metal. When enough metal is drawn off the "tap hole" is plugged with a refractory plug made of clay. [8] The cupola tender observes the furnace through the sight glass or peep hole in the ...
The cakes are heated in a liquation furnace, usually four or five at once, to a temperature above the melting point of lead (327°C), but below that of copper (1084 °C), so that the silver-rich lead melts and flows away. [5] As the melting point of lead is so low a high-temperature furnace is not required and it can be fuelled with wood. [7]