Iron pyrites element

After aluminium, iron is the most abundant metal and the fourth most abundant of all the elements it occurs chiefly as oxides (for example haematite (FCjO,), magnetite (lodestonej (FC3O4) and as iron pyrites FeSj- Free iron is found in meteorites, and it is probable that primitive man used this source of iron for tools and weapons. The extraction of iron began several thousand years ago, and it is still the most important metal in everyday life because of its abundance and cheapness, and its ability to be cast, drawn and forged for a variety of uses. 

Total 1991 world production of sulfur in all forms was 55.6 x 10 t. The largest proportion of this production (41.7%) was obtained by removal of sulfur compounds from petroleum and natural gas (see Sulfurremoval and recovery). Deep mining of elemental sulfur deposits by the Frasch hot water process accounted for 16.9% of world production mining of elemental deposits by other methods accounted for 5.0%. Sulfur was also produced by roasting iron pyrites (17.6%) and as a by-product of the smelting of nonferrous ores (14.0%). The remaining 4.8% was produced from unspecified sources. 

The principal direct raw materials used to make sulfuric acid are elemental sulfur, spent (contaminated and diluted) sulfuric acid, and hydrogen sulfide. Elemental sulfur is by far the most widely used. In the past, iron pyrites or related compounds were often used but as of the mid-1990s this type of raw material is not common except in southern Africa, China, Ka2akhstan, Spain, Russia, and Ukraine (96). A large amount of sulfuric acid is also produced as a by-product of nonferrous metal smelting, ie, roasting sulfide ores of copper, lead, molybdenum, nickel, 2inc, or others. 

Sulfur is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS, and sphalerite, ZnS (Fig. 15.11). Because these ores are so common, sulfur is a by-product of the extraction of a number of metals, especially copper. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H,S. The low melting point of sulfur (115°C) is utilized in the Frasch process, in which superheated water is used to melt solid sulfur underground and compressed air pushes the resulting slurry to the surface. Sulfur is also commonly found in petroleum, and extracting it chemically has been made inexpensive and safe by the use of heterogeneous catalysts, particularly zeolites (see Section 13.14). One method used to remove sulfur in the form of H2S from petroleum and natural gas is the Claus process, in which some of the H2S is first oxidized to sulfur dioxide ... 

TRW Meyers [Named after the three CalTech professors who founded the company Thompson, Ramo, and Wooldridge] A chemical method for desulfurizing coal. The iron pyrites is leached out with a hot aqueous solution of ferric sulfate, liberating elemental sulfur. The resulting ferrous sulfate solution is re-oxidized with air or oxygen ... 

Q Assign oxidation stales to the elements in the compounds Hj and KeSi (iron pyrites). 1... 

The pyrite sulfur is generally considered to be sulfur associated with iron pyrite, FeS2 In most cases only the second sulfur of the pyrite molecule can be considered to be in this class. This sulfur can be expelled from iron pyrite with moderate heating (approximately 500°C) to form iron sulfide, FeS, and elemental sulfur condensate in the cooler vapor space above the sample. 

Sulfur is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS2 and sphalerite, ZnS (Fig. 15.12). The mineral molybdenite, MoS2, is a soft rock with a metallic sheen and properties similar to those of graphite. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H2S. 

Silver is a rare element, which occurs naturally in its pure form as a white, ductile metal, and in ores. It has an average abundance of about 0.1 ppm in the earth s crust and about 0.3 ppm in soils. There are four oxidation states (0, 1 +, 2+, and 3+) the 0 and 1 + forms are much more common than the 2+ and 3+ forms. Silver occurs primarily as sulfides, in association with iron (pyrite), lead (galena), and tellurides, and with gold. Silver is found in surface waters in various forms (1) as the monovalent ion (e.g., sulphide, bicarbonate, or sulfate salts) (2) as part of more complex ions with chlorides and sulfates and (3) adsorbed onto particulate matter. 

In marine and lacustrine muds, the initial sulfide phase precipitated during early diagenesis is mackinawite (FeS09) which is subsequently converted to greigite (Fe3S4) and pyrite (FeS2) (85-89). This reaction path leads to the formation of framboidal pyrite (88.90). However, in salt marsh sediments under low pH and low sulfide ion activity conditions, direct precipitation of pyrite by reaction of ferrous iron with elemental sulfur without the formation of iron monosulfides as intermediates has been reported (85-87.89.91.92). This reaction is one possible pathway for the precipitation of pyrite as single crystals (89). 

Marcasite or white iron pyrites is the name given to a rhombic variety of pyrites which occurs m concretions, known locally as fairy balls and thunderbolts. Its crystallographic elements"are 5... 

It is found in non-elemental form in sulfates (gypsum), in sulfidic ores (e.g. iron pyrites and copper, zinc, lead, nickel and cobalt sulfides) and in fossil fuels. In natural gas and crude oil it occurs bonded to both hydrogen and carbon and... 

A total of 52.66 10 t of sulfur-containing raw materials (on the basis of sulfur content) was produced for further processing in 1993. 65% of this was elemental sulfur, 14% iron pyrites and the rest consists of flue gases from the roasting of non-ferrous metal sulfides, hydrogen sulfide and gypsum. 

Much of this early work was strictly pragmatic without any theory as we would understand it. It was necessary to be able to identify the best and richest ores, to be able to distinguish between superficial resemblances. The familiar properties of fool s gold, iron pyrites. FeS2, as compared with the element gold is a well-known example. 

Derivation From sulfur, pyrite (FeS2), hydrogen sulfide, or sulfur-containing smelter gases by the con-tactprocess (vanadiumpentoxide catalyst). The first step is combustion of elemental sulfur or roasting of iron pyrites to yield sulfur dioxide. Then follows the critical reaction, catalytic oxidation of sulfur dioxide to sulfur trioxide. 

Sulfur occurs as the free element—predominantly Sg molecules—and in metal sulfides such as galena, PbS iron pyrite, FeS2 and cinnabar, HgS. To a lesser extent, it occurs as metal sulfates such as barite, BaSO, and gypsum, CaSO - 2H2O, and in volcanic gases as H2S and SO2. 

In conjunction with XANES and X-ray diffraction, initial investigations involving synchrotron based X-ray microspectrometry (at ESRF) has revealed two types of reduced sulfur compounds in the timbers of the Mary Rose. Organosulfur compounds are found in the lignin-rich middle lamella between wood cell walls, mostly as thiols, disulfides and elemental sulfur, while inorganic iron sulfides including iron pyrite, occurs in separate particles in the cell lumen. 

Copper. For most antimonial alloys, this element does not have to be removed as alloys often specify the element. In calcium and soft-lead alloys, it is removed by the addition of sulfur (or iron pyrites/sulfur) to the bullion lead, as in the sulfur dressing process in primary refining. 

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