Search results
Results From The WOW.Com Content Network
The DNi process uses nitric acid, instead of sulphuric acid, to extract the nickel within a few hours and then the nitric acid is recycled. The DNi process has the major advantage of being able to treat both limonite and saprolite lateritic ores and is estimated to have less than half the capital and operating costs of HPAL or Ferronickel ...
Limonite (/ ˈ l aɪ m ə ˌ n aɪ t /) is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)· n H 2 O , although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely.
The term can also refer to the process by which waterborne minerals, such as calcium carbonate , iron oxide (hematite or limonite) or silica , replace organic material within the body of an organism that has died and was buried by sediments. [2] Mineralization may also refer to the product resulting from the process of mineralization.
The process of formation is called laterization. [2] Tropical weathering is a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils. The majority of the land area containing laterites is between the tropics of Cancer and Capricorn.
Examples of nonpolar surfaces include the rocksalt (100) surface, the rutile (100), (110) and (001) surfaces and the pervoskite (100) surface. [2] An example of a polar surface is the rocksalt (111) surface. [2] In general, a polar surface is less stable than a nonpolar surface because a dipole moment increases the surface Gibbs energy.
The concept of a transition state has been important in many theories of the rates at which chemical reactions occur. This started with the transition state theory (also referred to as the activated complex theory), developed independently in 1935 by Eyring, Evans and Polanyi, and introduced basic concepts in chemical kinetics that are still used today.
In chemistry, a phase-transfer catalyst or PTC is a catalyst that facilitates the transition of a reactant from one phase into another phase where reaction occurs. Phase-transfer catalysis is a special form of catalysis and can act through homogeneous catalysis or heterogeneous catalysis methods depending on the catalyst used.
Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure."