Misplaced Pages

#369630

103-807: Iron ore found in the hills had an average iron content of 35% and it was more than 45% in the northern flank of the hills and it is an important hill station in Tamil Nadu. 11°36′59.76″N 78°3′32.75″E  /  11.6166000°N 78.0590972°E  / 11.6166000; 78.0590972 This article related to a location in Salem district , Tamil Nadu , India is a stub . You can help Misplaced Pages by expanding it . Iron ore Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, or deep purple to rusty red. The iron

206-528: A 33% to 40% recovery of magnetite by weight, to produce a concentrate grading in excess of 64% iron by weight. The typical magnetite iron ore concentrate has less than 0.1% phosphorus , 3–7% silica , and less than 3% aluminium . As of 2019, magnetite iron ore is mined in Minnesota and Michigan in the United States , eastern Canada , and northern Sweden . Magnetite-bearing banded iron formation

309-696: A benchmark to be followed by the rest of the industry. Singapore Mercantile Exchange (SMX) has launched the world's first global iron ore futures contract, based on the Metal Bulletin Iron Ore Index (MBIOI) which uses daily price data from a broad spectrum of industry participants and independent Chinese steel consultancy and data provider Shanghai Steelhome's widespread contact base of steel producers and iron ore traders across China. The futures contract has seen monthly volumes over 1,500,000 t (1,500,000 long tons; 1,700,000 short tons) after eight months of trading. This move follows

412-514: A blast furnace more efficient. Others are added because they make the iron more fluid, harder, or give it some other desirable quality. The choice of ore, fuel, and flux determines how the slag behaves and the operational characteristics of the iron produced. Ideally, iron ore contains only iron and oxygen. In reality, this is rarely the case. Typically, iron ore contains a host of elements which are often unwanted in modern steel. Supernova A supernova ( pl. : supernovae or supernovas )

515-412: A journal article came the following year in a publication by Knut Lundmark , who may have coined it independently. Compared to a star's entire history, the visual appearance of a supernova is very brief, sometimes spanning several months, so that the chances of observing one with the naked eye are roughly once in a lifetime. Only a tiny fraction of the 100  billion stars in a typical galaxy have

618-453: A non-rotating star), it would no longer be able to support the bulk of its mass through electron degeneracy pressure and would begin to collapse. However, the current view is that this limit is not normally attained; increasing temperature and density inside the core ignite carbon fusion as the star approaches the limit (to within about 1%) before collapse is initiated. In contrast, for a core primarily composed of oxygen, neon and magnesium,

721-557: A one or two-letter designation. The first 26 supernovae of the year are designated with a capital letter from A to Z . Next, pairs of lower-case letters are used: aa , ab , and so on. Hence, for example, SN 2003C designates the third supernova reported in the year 2003. The last supernova of 2005, SN 2005nc, was the 367th (14 × 26 + 3 = 367). Since 2000, professional and amateur astronomers have been finding several hundred supernovae each year (572 in 2007, 261 in 2008, 390 in 2009; 231 in 2013). Historical supernovae are known simply by

824-424: A premium price. Due to the high density of hematite relative to associated silicate gangue, hematite beneficiation usually involves a combination of beneficiation techniques. One method relies on passing the finely-crushed ore over a slurry containing magnetite or other agent such as ferrosilicon which increases its density. When the density of the slurry is properly calibrated, the hematite will sink and

927-675: A rare type of very fast supernova with unusually strong calcium lines in their spectra. Models suggest they occur when material is accreted from a helium -rich companion rather than a hydrogen -rich star. Because of helium lines in their spectra, they can resemble type Ib supernovae, but are thought to have very different progenitors. The supernovae of type II can also be sub-divided based on their spectra. While most type II supernovae show very broad emission lines which indicate expansion velocities of many thousands of kilometres per second , some, such as SN 2005gl , have relatively narrow features in their spectra. These are called type IIn, where

1030-453: A relatively low-grade ore, they are also inexpensive to collect, as they do not have to be mined. Because of this, companies such as Magnetation have started reclamation projects where they use iron ore tailings as a source of metallic iron. The two main methods of recycling iron from iron ore tailings are magnetizing roasting and direct reduction. Magnetizing roasting uses temperatures between 700 and 900 °C (1,292 and 1,652 °F) for

1133-616: A source of iron ore. Prior to the industrial revolution, most iron was obtained from widely-available goethite or bog ore , for example, during the American Revolution and the Napoleonic Wars . Historically, much of the iron ore utilized by industrialized societies has been mined from predominantly hematite deposits with grades of around 70% Fe. These deposits are commonly referred to as "direct shipping ores" or "natural ores". Increasing iron ore demand, coupled with

SECTION 10

#1732783522370

1236-703: A stellar companion to raise its core temperature enough to ignite carbon fusion , at which point it undergoes runaway nuclear fusion, completely disrupting it. There are three avenues by which this detonation is theorised to happen: stable accretion of material from a companion, the collision of two white dwarfs, or accretion that causes ignition in a shell that then ignites the core. The dominant mechanism by which type Ia supernovae are produced remains unclear. Despite this uncertainty in how type Ia supernovae are produced, type Ia supernovae have very uniform properties and are useful standard candles over intergalactic distances. Some calibrations are required to compensate for

1339-474: A supernova's spectrum contains lines of hydrogen (known as the Balmer series in the visual portion of the spectrum) it is classified Type II ; otherwise it is Type I . In each of these two types there are subdivisions according to the presence of lines from other elements or the shape of the light curve (a graph of the supernova's apparent magnitude as a function of time). Type I supernovae are subdivided on

1442-606: A switch to index-based quarterly pricing by the world's three largest iron ore miners— Vale , Rio Tinto , and BHP —in early 2010, breaking a 40-year tradition of benchmark annual pricing. Iron is the most abundant element on earth but not in the crust. The extent of the accessible iron ore reserves is not known, though Lester Brown of the Worldwatch Institute suggested in 2006 that iron ore could run out within 64 years (that is, by 2070), based on 2% growth in demand per year. Geoscience Australia calculates that

1545-418: A time of under 1 hour to produce an iron concentrate (Fe 3 O 4 ) to be used for iron smelting. For magnetizing roasting, it is important to have a reducing atmosphere to prevent oxidization and the formation of Fe 2 O 3 because it is harder to separate as it is less magnetic. Direct reduction uses hotter temperatures of over 1,000 °C (1,830 °F) and longer times of 2–5 hours. Direct reduction

1648-655: A typically titanium -bearing magnetite, often with vanadium . These ores form a niche market, with specialty smelters used to recover the iron, titanium, and vanadium. These ores are beneficiated essentially similarly to banded iron formation ores, but usually are more easily upgraded via crushing and screening . The typical titanomagnetite concentrate grades 57% Fe, 12% Ti, and 0.5% V 2 O 5 . For every one ton of iron ore concentrate produced, approximately 2.5–3.0 tons of iron ore tailings will be discharged. Statistics show that there are 130 million tons of iron ore tailings discharged every year. If, for example,

1751-659: A value of $ 2.3 billion. 46% of Canada's iron ore comes from the Iron Ore Company of Canada mine, in Labrador City , Newfoundland , with secondary sources including the Mary River Mine in Nunavut . According to the U.S. Geological Survey's 2021 Report on iron ore, India is estimated to produce 59,000,000 t (58,000,000 long tons; 65,000,000 short tons) of iron ore in 2020, placing it as

1854-449: Is a dimensionless measure of the spectrum's frequency shift. High redshift searches for supernovae usually involve the observation of supernova light curves. These are useful for standard or calibrated candles to generate Hubble diagrams and make cosmological predictions. Supernova spectroscopy, used to study the physics and environments of supernovae, is more practical at low than at high redshift. Low redshift observations also anchor

1957-511: Is a high-volume, low-margin business, as the value of iron is significantly lower than base metals. It is highly capital intensive, and requires significant investment in infrastructure such as rail in order to transport the ore from the mine to a freight ship. For these reasons, iron ore production is concentrated in the hands of a few major players. World production averages 2,000,000,000 t (2.0 × 10 long tons; 2.2 × 10 short tons) of raw ore annually. The world's largest producer of iron ore

2060-531: Is a powerful and luminous explosion of a star . A supernova occurs during the last evolutionary stages of a massive star , or when a white dwarf is triggered into runaway nuclear fusion . The original object, called the progenitor , either collapses to a neutron star or black hole , or is completely destroyed to form a diffuse nebula . The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. The last supernova directly observed in

2163-500: Is debated and several alternative explanations, such as tidal disruption of a star by a black hole, have been suggested. SN 2013fs was recorded three hours after the supernova event on 6 October 2013, by the Intermediate Palomar Transient Factory . This is among the earliest supernovae caught after detonation, and it is the earliest for which spectra have been obtained, beginning six hours after

SECTION 20

#1732783522370

2266-428: Is expected to rise by a CAGR of 2% between 2023 and 2027, and industry analyst Fitch Solutions forecasted in 2021 that Brazil's annual production will reach 592,000,000 t (583,000,000 long tons; 653,000,000 short tons) by 2030. In 2017, Canadian iron ore mines produced 49,000,000 t (48,000,000 long tons; 54,000,000 short tons) of iron ore in concentrate pellets and 13.6 million tons of crude steel. Of

2369-510: Is followed by Japan and Korea, which consume a significant amount of raw iron ore and metallurgical coal . In 2006, China produced 588,000,000 t (579,000,000 long tons; 648,000,000 short tons) of iron ore, with an annual growth of 38%. Over the last 40 years, iron ore prices have been decided in closed-door negotiations between the small handful of miners and steelmakers which dominate both spot and contract markets. Until 2006, prices were determined in annual benchmark negotiations between

2472-454: Is generated, with matter reaching velocities on the order of 5,000–20,000 km/s , or roughly 3% of the speed of light. There is also a significant increase in luminosity, reaching an absolute magnitude of −19.3 (or 5 billion times brighter than the Sun), with little variation. The model for the formation of this category of supernova is a close binary star system. The larger of the two stars

2575-603: Is in the iron ranges around Lake Superior . These iron ranges occur in Minnesota and Michigan, which combined accounted for 93% of the usable iron ore produced in the United States in 2014. Seven of the nine operational open pit mines in the United States are located in Minnesota as well as two of the three tailings reclamation operations. The other two active open pit mines were located in Michigan . In 2016, one of

2678-709: Is mined extensively in Brazil as of 2019, which exports significant quantities to Asia , and there is a nascent and large magnetite iron ore industry in Australia . Direct-shipping iron ore (DSO) deposits (typically composed of hematite ) are currently exploited on all continents except Antarctica , with the largest intensity in South America , Australia, and Asia. Most large hematite iron ore deposits are sourced from altered banded iron formations and (rarely) igneous accumulations. DSO deposits are typically rarer than

2781-549: Is much variation in this type of event, and, in many cases, there may be no supernova at all, in which case they will have a less luminous light curve than the more normal SN type Ia. Abnormally bright type Ia supernovae occur when the white dwarf already has a mass higher than the Chandrasekhar limit, possibly enhanced further by asymmetry, but the ejected material will have less than normal kinetic energy. This super-Chandrasekhar-mass scenario can occur, for example, when

2884-579: Is required. It is therefore important to discover them well before they reach their maximum. Amateur astronomers , who greatly outnumber professional astronomers, have played an important role in finding supernovae, typically by looking at some of the closer galaxies through an optical telescope and comparing them to earlier photographs. Toward the end of the 20th century, astronomers increasingly turned to computer-controlled telescopes and CCDs for hunting supernovae. While such systems are popular with amateurs, there are also professional installations such as

2987-463: Is the raw material used to make pig iron , which is one of the main raw materials to make steel —98% of the mined iron ore is used to make steel. In 2011 the Financial Times quoted Christopher LaFemina, mining analyst at Barclays Capital, saying that iron ore is "more integral to the global economy than any other commodity, except perhaps oil ". Metallic iron is virtually unknown on

3090-481: Is the Brazilian mining corporation Vale , followed by Australian companies Rio Tinto Group and BHP . A further Australian supplier, Fortescue Metals Group Ltd, has helped bring Australia's production to first in the world. The seaborne trade in iron ore—that is, iron ore to be shipped to other countries—was 849,000,000 t (836,000,000 long tons; 936,000,000 short tons) in 2004. Australia and Brazil dominate

3193-414: Is the first to evolve off the main sequence , and it expands to form a red giant . The two stars now share a common envelope, causing their mutual orbit to shrink. The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion . At this point, it becomes a white dwarf star, composed primarily of carbon and oxygen. Eventually, the secondary star also evolves off

Kanjamalai - Misplaced Pages Continue

3296-425: Is used to produce sponge iron (Fe) to be used for steel-making. Direct reduction requires more energy, as the temperatures are higher and the time is longer and it requires more reducing agent than magnetizing roasting. Lower-grade sources of iron ore generally require beneficiation , using techniques like crushing, milling , gravity or heavy media separation , screening, and silica froth flotation to improve

3399-467: Is usually found in the form of magnetite ( Fe 3 O 4 , 72.4% Fe), hematite ( Fe 2 O 3 , 69.9% Fe), goethite ( FeO(OH) , 62.9% Fe), limonite ( FeO(OH)·n(H 2 O) , 55% Fe), or siderite ( FeCO 3 , 48.2% Fe). Ores containing very high quantities of hematite or magnetite, typically greater than about 60% iron, are known as natural ore or direct shipping ore , and can be fed directly into iron-making blast furnaces . Iron ore

3502-530: The Andromeda Galaxy . A second supernova, SN 1895B , was discovered in NGC 5253 a decade later. Early work on what was originally believed to be simply a new category of novae was performed during the 1920s. These were variously called "upper-class Novae", "Hauptnovae", or "giant novae". The name "supernovae" is thought to have been coined by Walter Baade and Zwicky in lectures at Caltech in 1931. It

3605-518: The Chandrasekhar limit ; electron capture ; pair-instability ; or photodisintegration . The table below lists the known reasons for core collapse in massive stars, the types of stars in which they occur, their associated supernova type, and the remnant produced. The metallicity is the proportion of elements other than hydrogen or helium, as compared to the Sun. The initial mass is the mass of

3708-905: The Chichester Range , the Hamersley Range and Koolyanobbing , Western Australia . Other types of ore are coming to the fore recently, such as oxidised ferruginous hardcaps, for instance laterite iron ore deposits near Lake Argyle in Western Australia. The total recoverable reserves of iron ore in India are about 9,602,000,000 t (9.450 × 10 long tons; 1.0584 × 10 short tons) of hematite and 3,408,000,000 t (3.354 × 10 long tons; 3.757 × 10 short tons) of magnetite . Chhattisgarh , Madhya Pradesh , Karnataka , Jharkhand , Odisha , Goa , Maharashtra , Andhra Pradesh , Kerala , Rajasthan , and Tamil Nadu are

3811-602: The Earth 's surface except as iron-nickel alloys from meteorites and very rare forms of deep mantle xenoliths . Although iron is the fourth-most abundant element in the Earth's crust , composing about 5%, the vast majority is bound in silicate or, more rarely, carbonate minerals, and smelting pure iron from these minerals would require a prohibitive amount of energy. Therefore, all sources of iron used by human industry exploit comparatively rarer iron oxide minerals, primarily hematite . Prehistoric societies used laterite as

3914-570: The Eta Carinae Great Outburst was noted. Supernovae in M101 (1909) and M83 (1923 and 1957) were also suggested as possible type IV or type V supernovae. These types would now all be treated as peculiar type II supernovae (IIpec), of which many more examples have been discovered, although it is still debated whether SN 1961V was a true supernova following an LBV outburst or an impostor. Supernova type codes, as summarised in

4017-664: The Katzman Automatic Imaging Telescope . The Supernova Early Warning System (SNEWS) project uses a network of neutrino detectors to give early warning of a supernova in the Milky Way galaxy. Neutrinos are subatomic particles that are produced in great quantities by a supernova, and they are not significantly absorbed by the interstellar gas and dust of the galactic disk. Supernova searches fall into two classes: those focused on relatively nearby events and those looking farther away. Because of

4120-535: The Milky Way was Kepler's Supernova in 1604, appearing not long after Tycho's Supernova in 1572, both of which were visible to the naked eye . The remnants of more recent supernovae have been found, and observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. A supernova in the Milky Way would almost certainly be observable through modern astronomical telescopes. The most recent naked-eye supernova

4223-564: The Pilbara region of Western Australia is approximately 844,000,000 t (831,000,000 long tons; 930,000,000 short tons) per year and rising. Gavin Mudd ( RMIT University ) and Jonathon Law ( CSIRO ) expect it to be gone within 30–50 years and 56 years, respectively. These 2010 estimates require ongoing review to take into account shifting demand for lower-grade iron ore and improving mining and recovery techniques (allowing deeper mining below

Kanjamalai - Misplaced Pages Continue

4326-413: The expansion of the universe , the distance to a remote object with a known emission spectrum can be estimated by measuring its Doppler shift (or redshift ); on average, more-distant objects recede with greater velocity than those nearby, and so have a higher redshift. Thus the search is split between high redshift and low redshift, with the boundary falling around a redshift range of z=0.1–0.3, where z

4429-533: The plural form supernovae ( /- v iː / ) or supernovas and is often abbreviated as SN or SNe. It is derived from the Latin word nova , meaning ' new ' , which refers to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky , who began using it in astrophysics lectures in 1931. Its first use in

4532-407: The silicate mineral fragments will float and can be removed. Iron is the world's most commonly used metal—steel, of which iron ore is the key ingredient, represents almost 95% of all metal used per year. It is used primarily in structures, ships, automobiles, and machinery. Iron-rich rocks are common worldwide, but ore-grade commercial mining operations are dominated by the countries listed in

4635-487: The speed of light . This drives an expanding shock wave into the surrounding interstellar medium , sweeping up an expanding shell of gas and dust observed as a supernova remnant. Supernovae are a major source of elements in the interstellar medium from oxygen to rubidium . The expanding shock waves of supernovae can trigger the formation of new stars . Supernovae are a major source of cosmic rays . They might also produce gravitational waves . The word supernova has

4738-431: The "n" stands for "narrow". A few supernovae, such as SN 1987K and SN 1993J , appear to change types: they show lines of hydrogen at early times, but, over a period of weeks to months, become dominated by lines of helium. The term "type IIb" is used to describe the combination of features normally associated with types II and Ib. Type II supernovae with normal spectra dominated by broad hydrogen lines that remain for

4841-420: The 13,600,000 t (13,400,000 long tons; 15,000,000 short tons) of steel 7,000,000 t (6,900,000 long tons; 7,700,000 short tons) was exported, and 43,100,000 t (42,400,000 long tons; 47,500,000 short tons) of iron ore was exported at a value of $ 4.6 billion. Of the iron ore exported, 38.5% of the volume was iron ore pellets with a value of $ 2.3 billion, and 61.5% was iron ore concentrates with

4944-691: The 62–64% Fe range. Granite and ultrapotassic igneous rocks were sometimes used to segregate magnetite crystals and form masses of magnetite suitable for economic concentration. A few iron ore deposits, notably in Chile , are formed from volcanic flows containing significant accumulations of magnetite phenocrysts . Chilean magnetite iron ore deposits within the Atacama Desert have also formed alluvial accumulations of magnetite in streams leading from these volcanic formations. Some magnetite skarn and hydrothermal deposits have been worked in

5047-429: The United States is estimated to have accounted for 2% of the world's iron ore output. In the United States there are twelve iron ore mines, with nine being open pit mines and three being reclamation operations. There were also ten pelletizing plants, nine concentration plants, two direct-reduced iron (DRI) plants, and one iron nugget plant that were operating in 2014. In the United States the majority of iron ore mining

5150-615: The actual explosion. The star is located in a spiral galaxy named NGC 7610 , 160 million light-years away in the constellation of Pegasus. The supernova SN 2016gkg was detected by amateur astronomer Victor Buso from Rosario , Argentina, on 20 September 2016. It was the first time that the initial "shock breakout" from an optical supernova had been observed. The progenitor star has been identified in Hubble Space Telescope images from before its collapse. Astronomer Alex Filippenko noted: "Observations of stars in

5253-688: The basis of their spectra, with type Ia showing a strong ionised silicon absorption line. Type I supernovae without this strong line are classified as type Ib and Ic, with type Ib showing strong neutral helium lines and type Ic lacking them. Historically, the light curves of type I supernovae were seen as all broadly similar, too much so to make useful distinctions. While variations in light curves have been studied, classification continues to be made on spectral grounds rather than light-curve shape. A small number of type Ia supernovae exhibit unusual features, such as non-standard luminosity or broadened light curves, and these are typically categorised by referring to

SECTION 50

#1732783522370

5356-543: The capacity to become a supernova, the ability being restricted to those having high mass and those in rare kinds of binary star systems with at least one white dwarf . The earliest record of a possible supernova, known as HB9, was likely viewed by an unknown prehistoric people of the Indian subcontinent and recorded on a rock carving in the Burzahama region of Kashmir , dated to 4500 ± 1000  BC . Later, SN 185

5459-402: The collapsing white dwarf will typically form a neutron star . In this case, only a fraction of the star's mass will be ejected during the collapse. Within a few seconds of the collapse process, a substantial fraction of the matter in the white dwarf undergoes nuclear fusion, releasing enough energy (1– 2 × 10   J ) to unbind the star in a supernova. An outwardly expanding shock wave

5562-411: The concentration of the ore and remove impurities. The results, high-quality fine ore powders, are known as fines. Magnetite is magnetic , and hence easily separated from the gangue minerals and capable of producing a high-grade concentrate with very low levels of impurities. The grain size of the magnetite and its degree of commingling with the silica groundmass determine the grind size to which

5665-454: The core against its own gravity; passing this threshold is the cause of all types of supernova except type Ia. The collapse may cause violent expulsion of the outer layers of the star resulting in a supernova. However, if the release of gravitational potential energy is insufficient, the star may instead collapse into a black hole or neutron star with little radiated energy. Core collapse can be caused by several different mechanisms: exceeding

5768-533: The country's " economic demonstrated resources " of iron currently amount to 24 gigatonnes , or 24,000,000,000 t (2.4 × 10 long tons; 2.6 × 10 short tons). Another estimate places Australia's reserves of iron ore at 52,000,000,000 t (5.1 × 10 long tons; 5.7 × 10 short tons), or 30% of the world's estimated 170,000,000,000 t (1.7 × 10 long tons; 1.9 × 10 short tons), of which Western Australia accounts for 28,000,000,000 t (2.8 × 10 long tons; 3.1 × 10 short tons). The current production rate from

5871-584: The depletion of high-grade hematite ores in the United States, led after World War II to the development of lower-grade iron ore sources, principally the use of magnetite and taconite . Iron ore mining methods vary by the type of ore being mined. There are four main types of iron ore deposits worked currently, depending on the mineralogy and geology of the ore deposits. These are magnetite, titanomagnetite , massive hematite, and pisolitic ironstone deposits. The origin of iron can be ultimately traced to its formation through nuclear fusion in stars, and most of

5974-400: The distance to their host galaxies. A second model for the formation of type Ia supernovae involves the merger of two white dwarf stars, with the combined mass momentarily exceeding the Chandrasekhar limit. This is sometimes referred to as the double-degenerate model, as both stars are degenerate white dwarfs. Due to the possible combinations of mass and chemical composition of the pair there

6077-401: The earliest example showing similar features. For example, the sub-luminous SN 2008ha is often referred to as SN 2002cx -like or class Ia-2002cx. A small proportion of type Ic supernovae show highly broadened and blended emission lines which are taken to indicate very high expansion velocities for the ejecta. These have been classified as type Ic-BL or Ic-bl. Calcium-rich supernovae are

6180-411: The event sufficiently for it to go unnoticed. The situation for Cassiopeia A is less clear; infrared light echoes have been detected showing that it was not in a region of especially high extinction. SN's identification With the development of the astronomical telescope , observation and discovery of fainter and more distant supernovae became possible. The first such observation was of SN 1885A in

6283-558: The extra mass is supported by differential rotation . There is no formal sub-classification for non-standard type Ia supernovae. It has been proposed that a group of sub-luminous supernovae that occur when helium accretes onto a white dwarf should be classified as type Iax . This type of supernova may not always completely destroy the white dwarf progenitor and could leave behind a zombie star . One specific type of supernova originates from exploding white dwarfs, like type Ia, but contains hydrogen lines in their spectra, possibly because

SECTION 60

#1732783522370

6386-451: The first moments they begin exploding provide information that cannot be directly obtained in any other way." The James Webb Space Telescope (JWST) has significantly advanced our understanding of supernovae by identifying around 80 new instances through its JWST Advanced Deep Extragalactic Survey (JADES) program. This includes the most distant spectroscopically confirmed supernova at a redshift of 3.6, indicating its explosion occurred when

6489-442: The gangue is separated during the beneficiation process and is removed as tailings . Taconite tailings are mostly the mineral quartz , which is chemically inert. This material is stored in large, regulated water settling ponds. The key parameters for magnetite ore being economic are the crystallinity of the magnetite, the grade of the iron within the banded iron formation host rock, and the contaminant elements which exist within

6592-439: The gradual change in properties or different frequencies of abnormal luminosity supernovae at high redshift, and for small variations in brightness identified by light curve shape or spectrum. There are several means by which a supernova of this type can form, but they share a common underlying mechanism. If a carbon - oxygen white dwarf accreted enough matter to reach the Chandrasekhar limit of about 1.44 solar masses (for

6695-800: The groundwater table). Brazil is the second-largest producer of iron ore after Australia, accounting for 16% of the world's iron ore production. After a somewhat sluggish production volume 2010-2020, partly due to the Mariana dam disaster in 2015 and the Brumadinho dam disaster in 2019, which halted the production at the two involved mines, production has increased steadily since 2021, when Brazil produced 431,000,000 t (424,000,000 long tons; 475,000,000 short tons). In 2022 it increased to 435,000,000 t (428,000,000 long tons; 480,000,000 short tons) and in 2023 to 440,000,000 t (430,000,000 long tons; 490,000,000 short tons). The Brazilian production

6798-564: The increasing number of discoveries has regularly led to the additional use of three-letter designations. After zz comes aaa, then aab, aac, and so on. For example, the last supernova retained in the Asiago Supernova Catalogue ; when it was terminated on 31 December 2017 bears the designation SN 2017jzp. Astronomers classify supernovae according to their light curves and the absorption lines of different chemical elements that appear in their spectra . If

6901-450: The iron and carbon smelting must be kept in an oxygen-deficient (reducing) state to promote the burning of carbon to produce CO and not CO 2 . The inclusion of even small amounts of some elements can have profound effects on the behavioral characteristics of a batch of iron or the operation of a smelter. These effects can be both good and bad, some catastrophically bad. Some chemicals are deliberately added, such as flux, which makes

7004-413: The iron from the oxygen, a stronger elemental bond must be presented to attach to the oxygen. Carbon is used because the strength of a carbon-oxygen bond is greater than that of the iron-oxygen bond at high temperatures. Thus, the iron ore must be powdered and mixed with coke , to be burnt in the smelting process. Carbon monoxide is the primary ingredient of chemically stripping oxygen from iron. Thus,

7107-895: The iron is thought to have originated in dying stars that are large enough to explode as supernovae . The Earth's core is thought to consist mainly of iron, but this is inaccessible from the surface. Some iron meteorites are thought to have originated from asteroids 1,000 km (620 mi) in diameter or larger. Banded iron formations (BIFs) are sedimentary rocks containing more than 15% iron composed predominantly of thinly-bedded iron minerals and silica (as quartz ). Banded iron formations occur exclusively in Precambrian rocks, and are commonly weakly-to-intensely metamorphosed . Banded iron formations may contain iron in carbonates ( siderite or ankerite ) or silicates ( minnesotaite , greenalite , or grunerite ), but in those mined as iron ores, oxides ( magnetite or hematite ) are

7210-431: The life of the decline are classified on the basis of their light curves. The most common type shows a distinctive "plateau" in the light curve shortly after peak brightness where the visual luminosity stays relatively constant for several months before the decline resumes. These are called type II-P referring to the plateau. Less common are type II-L supernovae that lack a distinct plateau. The "L" signifies "linear" although

7313-437: The light curve is extremely consistent across normal type Ia supernovae, having a maximum absolute magnitude of about −19.3. This is because typical type Ia supernovae arise from a consistent type of progenitor star by gradual mass acquisition, and explode when they acquire a consistent typical mass, giving rise to very similar supernova conditions and behaviour. This allows them to be used as a secondary standard candle to measure

7416-487: The light curve is not actually a straight line. Supernovae that do not fit into the normal classifications are designated peculiar, or "pec". Zwicky defined additional supernovae types based on a very few examples that did not cleanly fit the parameters for type I or type II supernovae. SN 1961i in NGC 4303 was the prototype and only member of the type III supernova class, noted for its broad light curve maximum and broad hydrogen Balmer lines that were slow to develop in

7519-463: The low-distance end of the Hubble curve , which is a plot of distance versus redshift for visible galaxies. As survey programmes rapidly increase the number of detected supernovae, collated collections of observations (light decay curves, astrometry, pre-supernova observations, spectroscopy) have been assembled. The Pantheon data set, assembled in 2018, detailed 1048 supernovae. In 2021, this data set

7622-423: The magnetite concentrate. The size and strip ratio of most magnetite resources is irrelevant, as a banded iron formation can be hundreds of meters thick, extend hundreds of kilometers along strike , and can easily come to more than three billion or more tonnes of contained ore. The typical grade of iron at which a magnetite-bearing banded iron formation becomes economic is roughly 25% iron, which can generally yield

7725-476: The magnetite-bearing BIF or other rocks which form its main source, or protolith rock, but are considerably cheaper to mine and process as they require less beneficiation due to the higher iron content. However, DSO ores can contain significantly higher concentrations of penalty elements, typically being higher in phosphorus, water content (especially pisolite sedimentary accumulations), and aluminium ( clays within pisolites). Export-grade DSO ores are generally in

7828-399: The main iron ore producers ( BHP Billiton , Rio Tinto , and Vale S.A. ) and Japanese importers. In 2006, Chinese company Baosteel began handling negotiations for the importer side. The Chinese government replaced Baosteel with China Iron and Steel Association as lead negotiator in 2009. Traditionally, the first deal reached between these the major producers and the major importers sets

7931-492: The main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass. The exact details of initiation and of the heavy elements produced in the catastrophic event remain unclear. Type Ia supernovae produce a characteristic light curve—the graph of luminosity as a function of time—after the event. This luminosity is generated by the radioactive decay of nickel -56 through cobalt -56 to iron -56. The peak luminosity of

8034-410: The mine tailings contain an average of approximately 11% iron, there would be approximately 1.41 million tons of iron wasted annually. These tailings are also high in other useful metals such as copper , nickel , and cobalt , and they can be used for road-building materials like pavement and filler and building materials such as cement, low-grade glass, and wall materials. While tailings are

8137-469: The most distant supernovae observed in 2003 appeared dimmer than expected. This supports the view that the expansion of the universe is accelerating . Techniques were developed for reconstructing supernovae events that have no written records of being observed. The date of the Cassiopeia A supernova event was determined from light echoes off nebulae , while the age of supernova remnant RX J0852.0-4622

8240-564: The naked eye, had a notable influence on the development of astronomy in Europe because they were used to argue against the Aristotelian idea that the universe beyond the Moon and planets was static and unchanging. Johannes Kepler began observing SN 1604 at its peak on 17 October 1604, and continued to make estimates of its brightness until it faded from naked eye view a year later. It was

8343-509: The past as high-grade iron ore deposits requiring little beneficiation . There are several granite-associated deposits of this nature in Malaysia and Indonesia . Other sources of magnetite iron ore include metamorphic accumulations of massive magnetite ore such as at Savage River , Tasmania , formed by shearing of ophiolite ultramafics . Another, minor, source of iron ores are magmatic accumulations in layered intrusions which contain

8446-480: The principal Indian producers of iron ore. World consumption of iron ore grows 10% per year on average with the main consumers being China, Japan, Korea, the United States, and the European Union. China is currently the largest consumer of iron ore, which translates to be the world's largest steel producing country. It is also the largest importer, buying 52% of the seaborne trade in iron ore in 2004. China

8549-481: The principal iron mineral. Banded iron formations are known as taconite within North America. The mining involves moving tremendous amounts of ore and waste. The waste comes in two forms: non-ore bedrock in the mine ( overburden or interburden locally known as mullock), and unwanted minerals, which are an intrinsic part of the ore rock itself ( gangue ). The mullock is mined and piled in waste dumps , and

8652-429: The quartz is left behind when the resultant powder is passed under a magnetic separator. Generally, most magnetite banded iron formation deposits must be ground to between 32 and 45 μm (0.0013 and 0.0018 in) in order to produce a low-silica magnetite concentrate. Magnetite concentrate grades are generally in excess of 70% iron by weight and usually are low in phosphorus, aluminium, titanium, and silica and demand

8755-407: The rock must be comminuted to enable efficient magnetic separation to provide a high-purity magnetite concentrate. This determines the energy inputs required to run a milling operation. Mining of banded iron formations involves coarse crushing and screening, followed by rough crushing and fine grinding to comminute the ore to the point where the crystallized magnetite and quartz are fine enough that

8858-446: The seaborne trade, with 72% of the market. BHP, Rio and Vale control 66% of this market between them. In Australia , iron ore is won from three main sources: pisolite " channel iron deposit " ore derived by mechanical erosion of primary banded-iron formations and accumulated in alluvial channels such as at Pannawonica, Western Australia ; and the dominant metasomatically altered banded iron formation -related ores such as at Newman ,

8961-491: The second supernova to be observed in a generation, after Tycho Brahe observed SN 1572 in Cassiopeia . There is some evidence that the youngest known supernova in our galaxy, G1.9+0.3 , occurred in the late 19th century, considerably more recently than Cassiopeia A from around 1680. Neither was noted at the time. In the case of G1.9+0.3, high extinction from dust along the plane of the galactic disk could have dimmed

9064-464: The seventh largest global center of iron ore production, behind Australia, Brazil, China, India, Russia, and South Africa. Producers of iron ore in Ukraine include Ferrexpo , Metinvest , and ArcelorMittal Kryvyi Rih . In 2014, mines in the United States produced 57,500,000 t (56,600,000 long tons; 63,400,000 short tons) of iron ore with an estimated value of $ 5.1 billion. Iron mining in

9167-451: The seventh-largest global center of iron ore production, behind Australia, Brazil, China, Russia, South Africa, and Ukraine. India's iron ore production in 2023 was 285,000,000 metric tonnes and was the fourth largest producer in the world. According to the U.S. Geological Survey's 2021 Report on iron ore, Ukraine is estimated to have produced 62,000,000 t (61,000,000 long tons; 68,000,000 short tons) of iron ore in 2020, placing it as

9270-452: The spectrum. SN 1961f in NGC 3003 was the prototype and only member of the type IV class, with a light curve similar to a type II-P supernova, with hydrogen absorption lines but weak hydrogen emission lines . The type V class was coined for SN 1961V in NGC 1058 , an unusual faint supernova or supernova impostor with a slow rise to brightness, a maximum lasting many months, and an unusual emission spectrum. The similarity of SN 1961V to

9373-514: The star prior to the supernova event, given in multiples of the Sun's mass, although the mass at the time of the supernova may be much lower. Type IIn supernovae are not listed in the table. They can be produced by various types of core collapse in different progenitor stars, possibly even by type Ia white dwarf ignitions, although it seems that most will be from iron core collapse in luminous supergiants or hypergiants (including LBVs). The narrow spectral lines for which they are named occur because

9476-469: The supernova is expanding into a small dense cloud of circumstellar material. It appears that a significant proportion of supposed type IIn supernovae are supernova impostors, massive eruptions of LBV-like stars similar to the Great Eruption of Eta Carinae . In these events, material previously ejected from the star creates the narrow absorption lines and causes a shock wave through interaction with

9579-409: The table above, are taxonomic : the type number is based on the light observed from the supernova, not necessarily its cause. For example, type Ia supernovae are produced by runaway fusion ignited on degenerate white dwarf progenitors, while the spectrally similar type Ib/c are produced from massive stripped progenitor stars by core collapse. A white dwarf star may accumulate sufficient material from

9682-401: The table aside. The major constraint to economics for iron ore deposits is not necessarily the grade or size of the deposits, because it is not particularly hard to geologically prove enough tonnage of the rocks exist. The main constraint is the position of the iron ore relative to market, the cost of rail infrastructure to get it to market, and the energy cost required to do so. Mining iron ore

9785-602: The two mines shut down. There have also been iron ore mines in Utah and Alabama ; however, the last iron ore mine in Utah shut down in 2014 and the last iron ore mine in Alabama shut down in 1975. Iron ores consist of oxygen and iron atoms bonded together into molecules. To convert it to metallic iron, it must be smelted or sent through a direct reduction process to remove the oxygen. Oxygen-iron bonds are strong, and to remove

9888-820: The universe was merely 1.8 billion years old. These findings offer crucial insights into the early universe's stellar evolution and the frequency of supernovae during its formative years. Because supernovae are relatively rare events within a galaxy, occurring about three times a century in the Milky Way, obtaining a good sample of supernovae to study requires regular monitoring of many galaxies. Today, amateur and professional astronomers are finding several hundred every year, some when near maximum brightness, others on old astronomical photographs or plates. Supernovae in other galaxies cannot be predicted with any meaningful accuracy. Normally, when they are discovered, they are already in progress. To use supernovae as standard candles for measuring distance, observation of their peak luminosity

9991-484: The white dwarf is surrounded by an envelope of hydrogen-rich circumstellar material . These supernovae have been dubbed type Ia/IIn , type Ian , type IIa and type IIan . The quadruple star HD 74438 , belonging to the open cluster IC 2391 the Vela constellation , has been predicted to become a non-standard type Ia supernova. Very massive stars can undergo core collapse when nuclear fusion becomes unable to sustain

10094-460: The year they occurred: SN 185, SN 1006, SN 1054, SN 1572 (called Tycho's Nova ) and SN 1604 ( Kepler's Star ). Since 1885 the additional letter notation has been used, even if there was only one supernova discovered that year (for example, SN 1885A, SN 1907A, etc.); this last happened with SN 1947A. SN , for SuperNova, is a standard prefix. Until 1987, two-letter designations were rarely needed; since 1988, they have been needed every year. Since 2016,

10197-532: Was SN 1987A , which was the explosion of a blue supergiant star in the Large Magellanic Cloud , a satellite galaxy of the Milky Way. Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-ignition of nuclear fusion in a white dwarf , or the sudden gravitational collapse of a massive star's core . Supernovae can expel several solar masses of material at speeds up to several percent of

10300-561: Was documented by Chinese astronomers in 185 AD. The brightest recorded supernova was SN 1006 , which was observed in AD 1006 in the constellation of Lupus . This event was described by observers in China, Japan, Iraq, Egypt and Europe. The widely observed supernova SN 1054 produced the Crab Nebula . Supernovae SN 1572 and SN 1604 , the latest Milky Way supernovae to be observed with

10403-464: Was estimated from temperature measurements and the gamma ray emissions from the radioactive decay of titanium-44 . The most luminous supernova ever recorded is ASASSN-15lh , at a distance of 3.82 gigalight-years . It was first detected in June 2015 and peaked at 570 billion  L ☉ , which is twice the bolometric luminosity of any other known supernova. The nature of this supernova

10506-495: Was expanded to 1701 light curves for 1550 supernovae taken from 18 different surveys, a 50% increase in under 3 years. Supernova discoveries are reported to the International Astronomical Union 's Central Bureau for Astronomical Telegrams , which sends out a circular with the name it assigns to that supernova. The name is formed from the prefix SN , followed by the year of discovery, suffixed with

10609-503: Was used, as "super-Novae", in a journal paper published by Knut Lundmark in 1933, and in a 1934 paper by Baade and Zwicky. By 1938, the hyphen was no longer used and the modern name was in use. American astronomers Rudolph Minkowski and Fritz Zwicky developed the modern supernova classification scheme beginning in 1941. During the 1960s, astronomers found that the maximum intensities of supernovae could be used as standard candles , hence indicators of astronomical distances. Some of

#369630