INTERNATIONAL YEAR OF THE PERIODIC TABLE FROM OUR ARCHIVES:
To celebrate the International Year of the Periodic Table, C&EN is re-releasing its favorite essays from a special 2003 collectors’ issue celebrating the elements
T
he name of the element cobalt has deep roots in the mythology of medieval mining. Mining was the basis for considerable wealth and power in regions where valuable metal ores were discovered. Myths were connected with the discovery of mineral resources, their extraction, and their processing. If one imagines medieval mining conditions—miners worked in almost complete darkness and under extremely dangerous circumstances—then it’s not surprising that ghosts and demons were prevalent in people’s minds in those days. The word “cobalt” is derived from “Kobold,” the name of a mischievous goblin in German mythology who, by the way, was closely related to another spirit called “Nickel.” Kobold was not really evil, but he loved to tease humans. Typically, like Nickel, he was blamed when ores that looked like those of valuable metals could not be smelted. An example of such an ore is the mineral cobaltite [(Co,Fe)AsS], which is sometimes found together with
elemental silver, and the following story is connected with this. At the end of the 16th century, the yield of the silver mines in the German region of Saxony declined from year to year. Kobold was blamed for stealing the silver and leaving behind worthless rock. Around this time, a young man skilled in the art of smelting arrived in Schneeberg, one of the main mining towns, and started to experiment with the strange dead rock
This shiny stack contains cobalt chips and a high-purity, 1 cm3 cobalt cube for comparison.
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C&EN | CEN.ACS.ORG | APRIL 1, 2019
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Co Cobalt Cobalt at a glance ▸ Name: From the German kobold, goblin or evil spirit. ▸ Atomic mass: 58.93. ▸ History: Minerals containing cobalt were used by the early civilizations of Egypt and Mesopotamia for coloring and dyeing. The element was isolated by Swedish chemist Georg Brandt in 1735. ▸ Occurrence: Found in the minerals cobaltite, smaltite, and erythrite and is often associated with nickel, silver, lead, copper, and iron ores. ▸ Appearance: Silvery blue, hard, brittle metal. ▸ Behavior: Stable in air, unaffected by water, and slowly attacked by dilute acids. It has low toxicity by ingestion but is a suspected carcinogen. ▸ Uses: Cobalt is essential to most species, including humans. It is used in alloys for magnets, in ceramics, in catalysts, and in paints. Cobalt is also used in magnetic and stainless steels. The metal is used in electroplating.
C R E D I T: A LC H EM I ST- HP/WI K I ME D I A CO M MO N S
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An essay on cobalt, by Ekkehard Schwab
With the advance of electrified power trains, cobalt will become an element of utmost strategic importance, although there, cobalt is in competition with materials based on manganese and nickel. that was assumed to be silver ore. Because he often did this at night and behind closed doors, he aroused the suspicions of the townspeople. They were just about to arrest and sentence him as a wizard when he found a way to prepare a brilliant blue pigment. The people of Schneeberg quickly realized that although the young man had not found silver, he had discovered a valuable new material—cobalt blue, which is still one of the technical uses for cobalt. In 2016, 128,000 metric tons of refined cobalt were produced worldwide, of which 69,000 metric tons are mined in the Democratic Republic of Congo, according to the British Geological Survey. China, Japan, and the U.S. are the top three cobalt-consuming countries. Today, cobalt is used mostly in cathodes for rechargeable batteries and in superalloys (chiefly for aerospace uses). Other uses are in magnet alloys, cemented carbides, other alloys (including steel), and chemical and ceramic uses. With the advance of electrified power trains, cobalt will become an element of utmost strategic importance, although there, cobalt is in competition with materials based on manganese and nickel. The irreplaceable material properties of superalloys and high-performance permanent magnets containing cobalt have caused the U.S. Defense Logistics Agency to stockpile strategic reserves of this once-undervalued element. In the chemical industry, cobalt is an essential constituent in important catalysts. Together with molybdenum, it is used in hydrodesulfurization catalysts for the manufacture of clean fuels. Cobalt catalysts are employed in the production of Fischer-Tropsch hydrocarbons and in a number of special hydrogenation processes (for example, for the production of amines.) Last but not least, they are key components in the multi-millionpound technology of hydroformylation; that is, the catalytic transformation of olefins into aldehydes using homogeneous catalysts. Finally, cobalt is an essential trace element in humans: About 40 ng of cobalt is required every day to meet the recommended dietary allowance of 2.4 mg of vitamin B12. Looking at the history of cobalt, it’s clear that the element has undergone a
significant transformation from an “ugly duckling” of no interest to miners into a “swan” of strategic industrial importance.
Ekkehard Schwab wrote the bulk of this essay in 2003. He updated information on
cobalt’s worldwide production and its uses for this re-release. In 1984, Schwab joined BASF, where he held various management positions in materials science and heterogeneous catalysis research. He retired in 2018.
APRIL 1, 2019 | CEN.ACS.ORG | C&EN
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