Mond process

Named after the chemist Ludwig Mond Mond process used to purify the metal and nickel is based on a so-called chemical transport reaction. Here, a solid (or more rarely liquid ) substance at a certain temperature with a gaseous reagent ( transport ) are reacted and converted to a gaseous product also (gas phase complex ). This product is then transferred back now elsewhere and at another temperature by back reaction in the much purer substance and the means of transport. One uses here in a skillful manner, the temperature dependence of the chemical equilibrium of.

In the case of the Moon the process of transport of carbon monoxide and transported via the gas phase connection, the nickel carbonyl Ni ( CO) 4 The transport is done by a cooler zone of the transport apparatus ( 80 ° C) to a hotter (200 ° C). Nickel carbonyl is formed voluntarily at a lower temperature and decomposes at a higher temperature in nickel and carbon monoxide. This fact is due to the fact that the reaction of the nickel to nickel tetracarbonyl is exothermic. This means that the equilibrium ( see Chemical equilibrium ) at high temperatures is located on the side of the elemental nickel. Impurities are not placed either at the lower temperature in the gas phase, or do not differ more at the higher temperature.

Similar transport reactions are also used for cleaning of some very high melting and boiling metals such as titanium, hafnium, molybdenum and tungsten in the so-called van Arkel -de Boer process. Transport are there halogens (especially iodine).