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Tantalum_-_Periodic_Table_of_Videos

Tantalum - Periodic Table of Videos

Ta.jpg

The Origins of Tantalum[]

Tantalum was first discovered in Sweden by Anders G. Ekeberg in 1802.  The name tantalum originates in Greek mythology; Tantalus was the father of Niobe, and niobium's properties are very similar to those of tantalum.

Tantalum's basic properties[]

Tantalum is the element 73 on the periodic table and has a gray blue color in its metallic form.  It has a density of 16.69 g·cm−3.  It has a melting point of 2850 Celsius, making it an excellent choice for heat resistance.

Where can Tantalum be Found?[]

Seve

Tantalite

ral of the top countries for Tantalum mining are Brazil, Mozambique, Rwanda, Australia, Canada, and Ethiopia.  Tantalum is extracted from Coltan (a combination of columbite and tantalite).  Coltan sold for the process of Tantalum mining usually contains at least 30% Ta2O5, though occasionally 20% Ta2O5 is acceptable.


Extraction of Tantalum[]

In order to extract Tantalum from the ore by heating it and then treating it with hydrofluoric acid. This results in the formation of complex fluorides of Tantalum and the dissolution of many impurities that are present.  The slurry is the filtered using methyl isobutyl ketone, which results in a highly purified tantalum fluoride.  In order to store it in a stable state, it is then made into K2TaF7.

The reactions for Tantalum extraction are as follows:      

Coltan, the compound from which Tantalum is extracted

Ta2O5 + 14 HF → 2 H2[TaF7] + 5 H2O

H2[TaF7] + 2 KF → K2[TaF7]↓ + 2 HF




Uses for Tantalum[]

  1. Tantalum carbide- used to prevent deformation of cutting tool under high temperatures
  2. Lithium tantalate- makes for clearer audio and visual performance in phones and televisions
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  3. Tantalum oxide- can increase the focal strength in lenses and enhances the image quality of film
  4. Tantalum powder- used in capacitors for electronic to increase reliability in a large scope of temperatures
  5. Tantalum fabricated sheets/plates/wires- used for prevention from corrosion and heat protection. Also used in prosthetics as it has little reaction with body fluids.
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  6. Ingot form-corrosion protection and high temperature resistance. Also used in memory for computer hard drives.

Political Impacts of Tantalum Mining[]

Mining of Tantalum in the form of “coltan” in the Democratic Republic of the Congo in central Africa prolonged a civil war lasting from 1998-2003 with side effects continuing today.  Local militia sells the coltan ore to fund war efforts.  A reform act from 2010 takes effect later this year; companies will be held legally responsible for knowing origin of their Ta.

Envirornmental Impacts of Tantalum mining

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Increasing demand for coltan for tantalum production has resulted in deforestation, pollution of waterways, and the killing of endangered species such as the gorilla for food. One example of this is the Kahuzi-Biega National park in the Democratic Republic of the Congo.  Their gorilla population has been decimated, losing over half of its members due to the encroaching coltan mines.  This coupled with the political war that the coltan mines are funding provide a frightening scenario for the future of this industry.

Niobium.jpg

Niobium[]

In the 1750's John Winthrop, known as the first governor of Conneticut in the United States, sent an ore over to England called Columbite. In 1801, from this ore, Charles Hatchett found this new element which he then called Columbium. Considerable confusion then arose surrounding the striking similarity between this new element and the known element tantalum. Upon further research of this "element", and after much dispute of how many elements actually existed "columbium", it was decided that only two elements were in it, one being tantalum, the other being named niobium, althought niobium remained under the name columbium until officially changing in 1949. 

Occurence and Production of Niobium[]

Niobium is said to have an occurrence of 20 ppm in the Earth's crust, making it the 33rd most common element found there. Although not found freely in nature, niobium is found in some minerals such as the formentioned columbite  ((Fe,Mn)(Nb,Ta)2O6). Niobium is also found in a mineral called pyrochlore ((Na,Ca)2Nb2O6(OH,F)). Two large deposits of pyrochlore were found in Brazil and Canada in the 1950's and these two countries remain the biggest producers of niobium mineral concentrates. As of 2013, the Brazilian company Cia. Brasileira de Metalurgia & Mineracao was said to control up to 85 percent of the world's niobium production, which has more than doubled in the past 10 years. 

Once niobium oxide is seperated from the minerals, it can be reduced to its metallic form. This is commonly done through a reaction with Iron(II) oxide and Aluminum:

3 Nb2O5 + Fe2O3 + 12 Al → 6 Nb + 2 Fe + 6 Al2O3

Characteristics of Niobium[]

Niobium (Nb) is located in the 5th group on the periodic table and is a lustrous gray metal. I has atomic number 41 and an atomic mass of 92.9. When pure, this metal is quite soft and ductile, impurities, however cause it to harden up. Niobium generally takes on a bluish tint when exposed to room air at room temperature for an extended period of time, but can also turn green or yellow. Because of the introduction of the lanthanides in the period below niobium, it shares many characteristics with tantalum, the element below it, because of similar size and electronegativity. Niobium is also one of the five refractory metals, along with tungstun, molybdenum, tantalum, and rhenium, which are highly resistant to both heat and water. 

Melting Point - 2750 K

Boiling Point - 5017 K

Electronegativity (Pauling) - 1.6

First and Second Ionization Energy - 652.1 kJ/mol and 1380 kJ/mol

Uses of Niobium[]

Niobium has a wide range of uses, the most common of which is steel production, followed by its use in superalloys.

Steel Production - Niobium is used as a microalloying element in steel production. Adding niobium to the steel

Steel niobium alloy

causes the production of niobium compounds such as niobium carbide and niobium nitride. These compounds then make the steel harder and tougher. Although only containing less that 0.1% niobium, adding niobium is and important addition and these alloys are used it a wide range of structures, such as automobiles and construction. 

Superalloys - As well as being used in steel, niobium is used in alloys of other metals such as nickel, cobalt, and iron superalloys which have a wide range of uses like components in jet engines, gas turbines, and turbo charger systems. Niobium causes a hardening in alloys making them alot tougher and resistant to heat. This makes them very usefel in spacecraft and they were widely used in the Apollo Program. 

Superconducting Magnets - Niobium-Germanium, Niobium-Tin, and other niobium alloys are commonly used as

A niobium-tin supermagnet

superconducting wires for superconducting magnets. These magnets are the used for Magnetic Resonance Imaging (MRI) and also in instruments like particle accelerators.  

Jewelry-  Because of its ability to take on different colors through an anodizing process, niobium is also used in jewelry. It has grown in popularity recenently because it is hypoallergenic and serves as an alternative for those alergic to most other metals.

Pacemakers - This hypoallergen

Examples of niobium jewelry in many colors

ic characteristic also makes it a good fit for pacemakers in the medical world. 







Sources[]

http://global.wisc.edu/outreach/k-12/webb/units/mining.htm

http://tanb.org/tantalum

http://www.chemicool.com/elements/niobium.html

http://www.ehow.com/about_5032210_niobium-jewelry.html

http://www.webelements.com/niobium/

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