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Cobalt is not found as a native metal but generally found in the form of ores. Cobalt is usually not mined alone, and tends to be produced as a by-product of nickel and copper mining activities. The main ores of cobalt are cobaltite, erythrite, glaucodot, and skutterudite.
Swedish chemist George Brandt (1694-1768) is credited with isolating cobalt circa 1735. He was able to show that cobalt was the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt.
http://periodic.lanl.gov/elements/27.html
Cobalt is not found as a native metal but generally found in the form of ores. Cobalt is usually not mined alone, and tends to be produced as a by-product of nickel and copper mining activities. The main ores of cobalt are cobaltite, erythrite, glaucodot, and skutterudite.
Swedish chemist George Brandt (1694-1768) is credited with isolating cobalt circa 1735. He was able to show that cobalt was the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt.
http://periodic.lanl.gov/elements/27.html
Converting Waste Heat Into ElectricityScientists at the Centre for Materials Science and Nanotechnology at the University of Oslo in Norway (UiO) are now collaborating with SINTEF (the Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology) to develop a new environmentally friendly technology called thermoelectricity, which can convert waste heat into electricity. To put it briefly, the technology involves making use of temperature differences.
Today: Toxic and expensive
Thermoelectric materials are put to many uses in space flight. When a space probe travels far enough away from the sun, its solar cells cease to work. Batteries have much too short a lifetime. Nuclear power cannot be used. However, a lump of Plutonium will do the trick.
With a temperature of a thousand degrees, it is hot. Outer space is cold. Thanks to the temperature difference, the space probe gets enough electricity.
Plutonium is a good solution for space probes that will not return to earth, but it is not a practical solution for cars and other earthly objects.
Thermoelectric materials are also currently used in the type of cooler bags that keep things cold without making use of their own cooling elements. These cooler bags are full of the elements Lead and Tellurium. Both of these substances are also toxic.
"We want to replace them with inexpensive and readily available substances. Moreover, there is not enough Tellurium to equip all of the cars in the world," says Ole Martin Løvvik, who is both an associate professor in the Department of Physics at the University of Oslo and a senior scientist at SINTEF.
Tomorrow: Environmentally friendly and inexpensive
With the current technology, it is possible to recover scarcely ten per cent of the lost energy. Together with the team of scientists led by Professor Johan Taftø, Løvvik is now searching for pollution-free, inexpensive materials that can recover fifteen per cent of all energy losses. That is an improvement of fully fifty per cent.
"I think we will manage to solve this problem with nanotechnology. The technology is simple and flexible and is almost too good to be true. In the long run, the technology can utilise all heat sources, such as solar energy and geothermal energy. The only limits are in our imagination," states Løvvik to the research magazine Apollon at University of Oslo
The new technology will initially be put to use in thermoelectric generators in cars. Several major automobile manufacturers are already interested. Løvvik and his colleagues are currently discussing the situation with General Motors.
"Modern cars need a lot of electricity. By covering the exhaust system with thermoelectric plates, the heat from the exhaust system can increase the car's efficiency by almost ten per cent at a single stroke. If we succeed, this will be a revolution in the modern automotive industry."
The new technology can also replace the hum of today's refrigerator.
"In the future, refrigerators can be soundless and built into cabinets without any movable parts and with the possibility of maintaining different temperatures in each compartment.
In order to extract as much energy as possible, the temperature difference should be as large as possible.
"Initially then, we want to utilise high-temperature waste heat, but there is also an upper limit."
If it becomes too hot, some materials will break down either by melting or by being transformed into other materials. That would mean that they wouldn't work any more.
Apparently self-contradictory.
In order to create thermoelectric materials, physicists have to resolve an apparent paradox. A metal conducts both electricity and heat. An insulator conducts neither electricity nor heat.
A good thermoelectric material ought to be a semi-conductor with very special properties: Its thermal resistance must be as high as possible at the same time as current must flow through it easily.
"This is not a simple combination, and it may even sound like a self-contradiction. The best solution is to create small structures that reflect the heat waves at the same time as the current is not reflected."
In order to understand why this is so, you must first understand how heat is dissipated. When a material becomes hot, the atoms vibrate. The hotter it becomes, the greater the vibrations, and when an atom vibrates, it will also affect the vibration of the adjacent atom.
When these vibrations spread through the material, they can be called heat waves. If we create barriers in the material so that some atoms vibrate at different frequencies from their adjacent atoms, the heat will not be so easily dissipated.
"Moreover, the atomic barrier must be created in such a way that it does not prevent the electric current from flowing through it."
Grinding nano-cavities at minus 196 degrees.
The scientists have found a method of creating these atomic barriers. The barriers are introduced densely in the special semi-conductors.
"We have achieved this by using a completely new "mill." Just as the miller grinds grain, the scientists will grind down semi-conductors to nano-sized grains. They will do that by cooling them down with liquid Nitrogen to minus 196 degrees. That makes the material more brittle, less sticky and easier to crush. It is important to grind down the grains as small as possible. Afterwards the grains are glued back together again, and in this way the barriers are created."
"The small irregularities in the barriers reflect the heat waves," says Løvvik.
The team of scientists uses an electron microscope to examine the micro-structures in the material.
"We have now discovered new nano-cavities in the materials and learned more about how they reflect heat waves."
The thermal resistance is measured in the Norwegian Micro and Nano Laboratories that are jointly operated by UiO and SINTEF. Løvvik's specialised field is mathematical models. With these models, he can predict how the atoms should be arranged in the materials.
Renaissance for cobalt
The scientists are now searching for the next generation of thermoelectric materials. They have just tested the cobalt arsenide mineral, skutterudite, which may be found at Skutterud at Blåfarveværket in Modum, Norway.
"It was just recently discovered that skutterudite may have atoms located in small nano-cavities. These cavities act as barriers to heat dissipation," concludes Løvvik.
oxidized the arsenic into the highly toxic and volatile arsenic oxide, adding to the notoriety of the ore.Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt circa 1735, showing it to be a previously unknown element, distinct from bismuth and other traditional metals. Brandt called it a new "semi-metal". He showed that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt. Cobalt became the first metal to be discovered since the pre-historical period. All other known metals (iron, copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no recorded discoverers.During the 19th century, a significant part of the world's production of cobalt blue (a dye made with cobalt compounds and alumina) and smalt (cobalt glass powdered for use for pigment purposes in ceramics and painting) was carried out at the Norwegian Blaafarveværket. The first mines for the production of smalt in the 16th century were located in Norway, Sweden, Saxony and Hungary. With the discovery of cobalt ore in New Caledonia in 1864, the mining of cobalt in Europe declined. With the discovery of ore deposits in Ontario, Canada in 1904 and the discovery of even larger deposits in the Katanga Province in the Congo in 1914, the mining operations shifted again. When the Shaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production. The impact on the world cobalt economy from this conflict was smaller than expected: cobalt is a rare metal, the pigment is highly toxic, and the industry had already established effective ways for recycling cobalt materials. In some cases, industry was able to change to cobalt-free alternatives.In 1938, John Livingood and Glenn T. Seaborg discovered the radioisotope cobalt-60. This isotope was famously used at Columbia University in the 1950s to establish parity violation in radioactive beta decay.After World War II, the US wanted to guarantee the supply of cobalt ore for military uses (as the Germans had been doing) and prospected for cobalt within the U.S. border. An adequate supply of the ore was found in Idaho near Blackbird canyon in the side of a mountain. The firm Calera Mining Company started production at the site.It has been argued that cobalt will be one of the main objects of geopolitical competition in a world running on renewable energy and dependent on batteries, but this perspective has also been criticised for underestimating the power of economic incentives for expanded production. The stable form of cobalt is produced in supernovae through the r-process. It comprises 0.0029% of the Earth's crust. Free cobalt (the native metal) is not found on Earth because of the oxygen in the atmosphere and the chlorine in the ocean. Both are abundant enough in the upper layers of the Earth's crust to prevent native metal cobalt from forming. Except as recently delivered in meteoric iron, pure cobalt in native metal form is unknown on Earth. The element has a medium abundance but natural compounds of cobalt are numerous and small amounts of cobalt compounds are found in most rocks, soils, plants, and animals.In nature, cobalt is frequently associated with nickel. Both are characteristic components of meteoric iron, though cobalt is much less abundant in iron meteorites than nickel. As with nickel, cobalt in meteoric iron alloys may have been well enough protected from oxygen and moisture to remain as the free (but alloyed) metal, though neither element is seen in that form in the ancient terrestrial crust.Cobalt in compound form occurs in copper and nickel minerals. It is the major metallic component that combines with sulfur and arsenic in the sulfidic cobaltite (CoAsS), safflorite (CoAs2), glaucodot ((Co,Fe)AsS), and skutterudite (CoAs3) minerals. The mineral cattierite is similar to pyrite and occurs together with vaesite in the copper deposits of Katanga Province. When it reaches the atmosphere, weathering occurs; the sulfide minerals oxidize and form pink erythrite ("cobalt glance": Co3(AsO4)2·8H2O) and spherocobaltite (CoCO3).Cobalt is also a constituent of tobacco smoke. The tobacco plant readily absorbs and accumulates heavy metals like cobalt from the surrounding soil in its leaves. These are subsequently inhaled during tobacco smoking. Cobalt is a trace metal involved in photosynthesis and nitrogen fixation detected in most ocean basins and is a limiting micronutrient for phytoplankton and cyanobacteria. The Co-containing complex cobalamin is only synthesized by cyanobacteria and a few archaea, so dissolved cobalt concentrations are low in the upper ocean. Like Mn and Fe, Co has a hybrid profile of biological uptake by phytoplankton via photosynthesis in the upper ocean and scavenging in the deep ocean, although most scavenging is limited by complex organic ligands. Co is recycled in the ocean by decaying organic matter that sinks below the upper ocean, although most is scavenged by oxidizing bacteria.Sources of cobalt for many ocean bodies include rivers and terrestrial runoff with some input from hydrothermal vents. In the deep ocean, cobalt sources are found lying on top of seamounts (which can be large or small) where ocean currents sweep the ocean floor to clear sediment over the span of millions of years allowing them to form as ferromanganese crusts. Although limited mapping of the seafloor has been done, preliminary investigation indicates that there is a large amount of these cobalt-rich crusts located in the Clarion Clipperton Zone, an area garnering increasing interest for deep sea mining ventures due to the mineral-rich environment within its domain. Anthropogenic input contributes as a non-natural source but in very low amounts. Dissolved cobalt (dCo) concentrations across oceans are controlled primarily by reservoirs where dissolved oxygen concentrations are low. The complex biochemical cycling of cobalt in the ocean is still somewhat misunderstood, but patterns of higher concentrations have been found in areas of low oxygen such as the Oxygen Minimum Zone (OMZ) in the Southern Atlantic Ocean.Cobalt is considered toxic for marine environments at high concentrations. Safe concentrations fall around 18 μg/l in marine waters for plankton such as diatoms. Most coastal toxicity levels are influenced by anthropogenic input like sewage runoff and burning of fossil fuels. High levels of Co and Se have been recorded in seafood sourced from coastal areas with higher levels of the trace metals. Although scientists are aware of threatening toxicity, less attention has been paid compared to other trace metals like mercury and lead in contaminated water systems. The main ores of cobalt are cobaltite, erythrite, glaucodot and skutterudite (see above), but most cobalt is obtained by reducing the cobalt by-products of nickel and copper mining and smelting.Since cobalt is generally produced as a by-product, the supply of cobalt depends to a great extent on the economic feasibility of copper and nickel mining in a given market. Demand for cobalt was projected to grow 6% in 2017.Several methods exist to separate cobalt from copper and nickel, depending on the concentration of cobalt and the exact composition of the used ore. One method is froth flotation, in which surfactants bind to ore components, leading to an enrichment of cobalt ores. Subsequent roasting converts the ores to cobalt sulfate, and the copper and the iron are oxidized to the oxide. Leaching with water extracts the sulfate together with the arsenates. The residues are further leached with sulfuric acid, yielding a solution of copper sulfate
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