The mineral pyrite, or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.
Limonite 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)·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 2500 BP.
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications.
Arsenopyrite is an iron arsenic sulfide (FeAsS). It is a hard metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases elemental sulfur. When arsenopyrite is heated, it produces sulfur and arsenic vapor. With 46% arsenic content, arsenopyrite, along with orpiment, is a principal ore of arsenic. When deposits of arsenopyrite become exposed to the atmosphere, the mineral slowly converts into iron arsenates. Arsenopyrite is generally an acid-consuming sulfide mineral, unlike iron pyrite which can lead to acid mine drainage.
Chalcopyrite ( KAL-kə-PY-ryte, -koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green-tinged black.
Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. Sulfide also refers to chemical compounds large families of inorganic and organic compounds, e.g. lead sulfide and dimethyl sulfide. Hydrogen sulfide (H2S) and bisulfide (SH−) are the conjugate acids of sulfide.
Jarosite is a basic hydrous sulfate of potassium and ferric iron (Fe-III) with a chemical formula of KFe3(SO4)2(OH)6. This sulfate mineral is formed in ore deposits by the oxidation of iron sulfides. Jarosite is often produced as a byproduct during the purification and refining of zinc and is also commonly associated with acid mine drainage and acid sulfate soil environments.
Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper ores consists of a series of physical, chemical and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors.
Bacteria biooxidation is an oxidation process caused by microbes where the valuable metal remains in the solid phase. In this process, the metal remains in the solid phase and the liquid can be discarded. Bacterial oxidation is a biohydrometallurgical process developed for pre-cyanidation treatment of refractory gold ores or concentrates. The bacterial culture is a mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans. The bacterial oxidation process comprises contacting refractory sulfide ROM ore or concentrate with a strain of the bacterial culture for a suitable treatment period under an optimum operating environment. The bacteria oxidise the sulfide minerals, thus liberating the occluded gold for subsequent recovery via cyanidation.
Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals. Pyrometallurgical treatment may produce products able to be sold such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing. Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like iron, copper, zinc, chromium, tin, and manganese.
Gold extraction refers to the processes required to extract gold from its ores. The great majority of gold is extracted from dilute ores using a combination of chemical processes. About 2000 tons are obtained from the earth annually, plus another 300 tons from recycling.
Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite (Cu2S), covellite (CuS), digenite (Cu18S10), and djurleite (Cu31S16) are deposited by the descending surface waters.
In geology, a redox buffer is an assemblage of minerals or compounds that constrains oxygen fugacity as a function of temperature. Knowledge of the redox conditions (or equivalently, oxygen fugacities) at which a rock forms and evolves can be important for interpreting the rock history. Iron, sulfur, and manganese are three of the relatively abundant elements in the Earth's crust that occur in more than one oxidation state. For instance, iron, the fourth most abundant element in the crust, exists as native iron, ferrous iron (Fe2+), and ferric iron (Fe3+). The redox state of a rock affects the relative proportions of the oxidation states of these elements and hence may determine both the minerals present and their compositions. If a rock contains pure minerals that constitute a redox buffer, then the oxygen fugacity of equilibration is defined by one of the curves in the accompanying fugacity-temperature diagram.
Roasting is a process of heating a sulfide ore to a high temperature in the presence of air. It is a step in the processing of certain ores. More specifically, roasting is often a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component(s). Often before roasting, the ore has already been partially purified, e.g. by froth flotation. The concentrate is mixed with other materials to facilitate the process. The technology is useful in making certain ores usable but it can also be a serious source of air pollution.
Biomining is the technique of extracting metals from ores and other solid materials typically using prokaryotes, fungi or plants. These organisms secrete different organic compounds that chelate metals from the environment and bring it back to the cell where they are typically used to coordinate electrons. It was discovered in the mid 1900s that microorganisms use metals in the cell. Some microbes can use stable metals such as iron, copper, zinc, and gold as well as unstable atoms such as uranium and thorium. Large chemostats of microbes can be grown to leach metals from their media. These vats of culture can then be transformed into many marketable metal compounds. Biomining is an environmentally friendly technique compared to typical mining. Mining releases many pollutants while the only chemicals released from biomining is any metabolites or gasses that the bacteria secrete. The same concept can be used for bioremediation models. Bacteria can be inoculated into environments contaminated with metals, oils, or other toxic compounds. The bacteria can clean the environment by absorbing these toxic compounds to create energy in the cell. Bacteria can mine for metals, clean oil spills, purify gold, and use radioactive elements for energy.
The Getchell Mine is an underground gold mine in the Potosi Mining District of Humboldt County, Nevada, on the east flank of the Osgood Mountains, 35 miles northeast of Winnemucca. Prospectors Edward Knight and Emmet Chase discovered gold in 1933 and located the first claims in 1934. With the financial backing of Noble Getchell and George Wingfield, the Getchell Mine, Inc. was organized in 1936 and the mine was brought into production in 1938.
Zinc smelting is the process of converting zinc concentrates into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling point. At temperatures typically used for smelting metals, zinc is a gas that will escape from a furnace with the flue gas and be lost, unless specific measures are taken to prevent it.
Cobalt extraction refers to the techniques used to extract cobalt from its ores and other compound ores. Several methods exist for the separation of cobalt from copper and nickel. They depend on the concentration of cobalt and the exact composition of the ore used.
