Minerals hematite

Minerals. Iron-bearing minerals are numerous and are present in most soils and rocks. However only a few minerals are important sources of iron and thus called ores. Table 2 shows the principle iron-bearing minerals. Hematite is the most plentiful iron mineral mined, followed by magnetite, goethite, siderite, ilmenite, and pyrite. Siderite is unimportant in the United States, but is an important source of iron in Europe. Tlmenite is normally mined for titania with iron as a by-product. Pyrite is roasted to recover sulfur in the form of sulfur dioxide, leaving iron oxide as a by-product. 

In a second example, we calculate how pH affects sorption onto hydrous ferric oxide, expanding on our discussion (Section 10.4) of Dzombak and Morel s (1990) surface complexation model. We start as before, setting the dataset of surface reactions, suppressing the ferric minerals hematite (Fe203) and goethite (FeOOH), and specifying the amount of ferric oxide [represented in the calculation by Fe(OH)3 precipitate] in the system... 

Oceanic zooplankton species, wax esters in, 26 204-205 Ocean ranching, 3 198 Ocean raw materials, 17 684-699 consolidated deposits of, 17 691-694 economic aspects of, 17 697 fluid deposits of, 17 694-695 minerals recovery from, 17 695—697 unconsolidated deposits of, 17 686-691 Ocean resources, global, 17 684—686 Oceans, selenium content of, 22 11. See also Marine entries Seawater Ocean thermal energy conversion (OTEC) power plants, 13 267, 268 26 92-93 Ocean transportation, 25 328 Ochratoxin A, 7 267-268 Ochre (mineral hematite) color, 7 333... 

Most iron produced today is from its oxide minerals, hematite and magnetite. The process involves reducing mineral iron with carbon in a blast fur-... 

Iron(lll) oxide occurs in nature as the mineral hematite. It is the principal... 

Iron metal can be produced from the mineral hematite, Fe203, by reaction with carbon. How many kilograms of iron are present in 105 kg of hematite ... 

Elemental iron, the major element in Earth s core, is the fourth most abundant element in Earth s crust (about 5.0% by mass overall, 0.5%-5% in soils, and approximately 2.5 parts per billion in seawater.) In the crust, iron is found mainly as the oxide minerals hematite, Fe203, and magnetite, Fe304. Other common mineral forms are siderite, FeC03, and various forms of FeO(OH). Iron is an essential element in almost all living organisms. In the human body, its concentration ranges between 3 and 380 parts per million (ppm) in bone, 380-450 ppm in blood, and 20-1,400 ppm in tissue. 

A reaction that involves chemical species in more than one phase is termed heterogeneous.1 An example is the composite reaction describing the reductive dissolution of the common soil mineral hematite (a-Fe ) in the presence of visible light by oxalic acid (H2C204), a ubiquitous plant litter degradation product ... 

Natural and oxides of iron are mined either as the mineral hematite (Fe203) or as hematite in its hydrated form. Indian red is a naturally occurring mineral whose ferric oxide content may vary from 80 to 95 percent, the remainder being clay and silica. It is made by grinding hematite and floating off the fines for use. 

Iron forms many compounds. In some of them, such as ferrous oxide, FcO, the iron atom is said to be bivalent in ferrous oxide it may be described as having transferred two electrons to the oxygen atom, leaving it a doubly charged ion, Fe++. In other compounds, such as ferric oxide (the mineral hematite), Fe203, the iron atom has valence three, corresponding to the triply charged ion, Fe+++. The ferric compounds are more stable than the ferrous compounds. 

The following example demonstrates how remarkably large the total area of a substance becomes when a given amount of it occurs in smaller and smaller particles. The example substance is the mineral hematite (a-Fe203). Table 10.1 shows the profound increase in surface area that results... 

TABLE 10.1 The total surface area of a 1 cm volume of the mineral hematite a-Fe203l, density = 5.26 g/cm GFW = 160 g/mol, when it is subdivided into smaller and smaller cubes... 

Iron is the fourth most abundant element in the Earths crust. Iron is often found in the minerals hematite, magnetite, and mar-casite. Large deposits of iron-bearing minerals are found primarily in Australia, Canada, France, India, South Africa, and the United States. The iron used in industry comes from these mineral deposits. In addition, the interior of Earth—called the core—is believed to be composed primarily of iron. Earths interior is extremely hot—hot enough to melt iron into a molten state. 

The minerals hematite (Fc203) and magnetite (Fe304) exist in equilibrium with atmospheric oxygen ... 

Ferric Oxide. Ferric sesquioxide jeweler s rouge. Fe203 mol wt 159.70. Fe 69.94%, O 30.06%. a-Form occurs in nature as the mineral hematite, v-Form occurs in nature as the mineral maghemite prepd by dehydration of a -FeO(OH) Giovanoli, Briitsch, Chimia 28, 188 (1974). 

The major Fe oxides and oxyhydroxides may exist as crystalline minerals (hematite, goethite, lepidocrocite, maghemite, and magnetite), short-range-ordered... 

Iron metal can be refined from the mineral hematite (Fe203). One way of converting the mineral to iron is to react it with carbon monoxide, as shown below ... 

Fc203 better known as rust is a dark red substance, which occurs in nature as the mineral hematite, and is the principal ore for iron. It could be one of the economically feasible magnetic filler in the preparation of NR matrix. ... 

Assuming that the activity coefficient jf is 1.0, again in this case an excellent approximation, we can calculate the partial pressure of oxygen in a gas phase in equilibrium with the two minerals hematite and magnetite. 

Abundant Metals and Their Uses. The abundant metals are those found in the highest concentrations within the Earth. Iron minerals are used to make steel, which is used to make automobiles, buildings, roads, bridges, major appliances, and construction materials such as nails. The major iron ore minerals, hematite and magnetite (both iron oxides), are converted to steel by heating them to a high temperature with coke and limestone to form molten steel, which contains up to 2 percent carbon to harden the iron. 

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