Ads
related to: homemade crucible for melting goldebay.com has been visited by 1M+ users in the past month
Search results
Results from the WOW.Com Content Network
Crucibles used in Czochralski method Melting gold in a graphite crucible Three crucibles used by Thomas Edison. Crucibles are used in the laboratory to contain chemical compounds when they are heated to extremely high temperatures. Crucibles are available in several sizes and typically come with a correspondingly-sized lid. [20]
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.
The reaction with hydrochloric acid is an equilibrium reaction that favors formation of tetrachloroaurate(III) anions. This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become chloroauric acid. In addition, gold may be dissolved by the chlorine present in aqua regia.
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.
In contrast to the use of mercury (which relies on amalgamation of the gold to coalesce it and separate it from impurities) this method relies on borax's ability to lower all the minerals' melting points. Since the gold is usually the heaviest of these minerals, it allows for concentrating the gold on the bottom of the crucible.
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.
The process can be carried out in a horizontal or vertical orientation, and usually involves a rotating crucible/ampoule to stir the melt. [ 1 ] The Bridgman method is a popular way of producing certain semiconductor crystals such as gallium arsenide , for which the Czochralski method is more difficult.
One process for X-ray fluorescence assay involves melting the material in a furnace and stirring to make a homogeneous mix. Following this, a sample is taken from the centre of the molten sample. Samples are typically taken using a vacuum pin tube. [4] The sample is then tested by X-ray fluorescence spectroscopy. Metallurgical assay is ...
Ads
related to: homemade crucible for melting goldebay.com has been visited by 1M+ users in the past month