.
Afghanistan sits on $3 trillion in minerals - CaRe > .
History of Afghanistan summarized - Epim > .
Tech Companies Depend on China for Rare Earths. Can It Change? | WSJ > .
History of Afghanistan summarized - Epim > .
Papier-Mâché Tiger - Afghan Debacle ..
Rare Earths ↠
The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide. They are called lanthanides because the elements in the series are chemically similar to lanthanum. Since "lanthanide" means "like lanthanum", it has been argued that lanthanum cannot logically be a lanthanide, but IUPAC acknowledges its inclusion based on common usage.
All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell. There is some dispute on whether lanthanum or lutetium is a d-block element, but lutetium is usually considered so by those who study the matter; it is included due to its chemical similarities with the other 14. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.
In presentations of the periodic table, the f-block elements are customarily shown as two additional rows below the main body of the table, This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the 4f and 5f series in their proper places, as parts of the table's sixth and seventh rows (periods).
The 1985 International Union of Pure and Applied Chemistry "Red Book" (p. 45) recommends that "lanthanoid" is used rather than "lanthanide". The ending "-ide" normally indicates a negative ion. However, owing to wide current use, "lanthanide" is still allowed.
https://en.wikipedia.org/wiki/Lanthanide .
Currently (2016), there are only a few mines that supply the entire world's demand for REEs and most of them are located in China. The largest REE mine in the world, Bayan Obo, alone provides 40-50% of all REEs. In 2010, Bayan Obo and other REE mines in China provided approximately 97% of the global supply (Humphries, 2012).
In the late 19th century, Afghanistan became a buffer state in the "Great Game" between British India and the Russian Empire. In the First Anglo-Afghan War, the British East India Company seized control of Afghanistan briefly, but following the Third Anglo-Afghan War in 1919 the country was free of foreign influence, eventually becoming a monarchy under Amanullah Khan, until almost 50 years later when Zahir Shah was overthrown and a republic was established. In 1978, after a second coup, Afghanistan first became a socialist state, evoking the Soviet–Afghan War in the 1980s against mujahideen rebels. By 1996, most of the country was captured by the Islamic fundamentalist Taliban, who ruled as a totalitarian regime for over five years; they were removed from power after the US invasion in 2001 but still control a significant portion of the country. The ongoing war between the government and the Taliban has contributed to the perpetuation of Afghanistan's problematic human rights record including complications of women's rights, with numerous abuses committed by both sides, such as the killing of civilians.
Afghanistan is a unitary presidential Islamic republic. The country has high levels of terrorism, poverty, child malnutrition, and corruption. It is a member of the United Nations, the Organisation of Islamic Cooperation, the South Asian Association for Regional Cooperation, the Group of 77, the Economic Cooperation Organization, and the Non-Aligned Movement. Afghanistan's economy is the world's 96th largest, with a gross domestic product (GDP) of $72.9 billion by purchasing power parity; the country fares much worse in terms of per-capita GDP (PPP), ranking 169th out of 186 countries as of 2018.
Rare Earths ↠
The "rare earth" lanthanide series (more correctly, lanthanoid) series of chemical
elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the
chemically similar elements scandium and yttrium, are often collectively known as
the rare earth
elements.
The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide. They are called lanthanides because the elements in the series are chemically similar to lanthanum. Since "lanthanide" means "like lanthanum", it has been argued that lanthanum cannot logically be a lanthanide, but IUPAC acknowledges its inclusion based on common usage.
All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell. There is some dispute on whether lanthanum or lutetium is a d-block element, but lutetium is usually considered so by those who study the matter; it is included due to its chemical similarities with the other 14. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.
In presentations of the periodic table, the f-block elements are customarily shown as two additional rows below the main body of the table, This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the 4f and 5f series in their proper places, as parts of the table's sixth and seventh rows (periods).
The 1985 International Union of Pure and Applied Chemistry "Red Book" (p. 45) recommends that "lanthanoid" is used rather than "lanthanide". The ending "-ide" normally indicates a negative ion. However, owing to wide current use, "lanthanide" is still allowed.
https://en.wikipedia.org/wiki/Lanthanide .
China no longer accounts for all of the global REE supply due to increased production in the rest of the world. There are only four REE-specific mines outside of China, two of which opened in the past year (~2015). Other mines worldwide only produce REEs as a byproduct. These REE-specific mines are Mountain Pass in the United States, Mount Weld in Australia, Lovozero in Russia, and Kerala in India. However, these mines are not the only locations of REE deposits.
As the demand for REEs increases, it will become both necessary and more economically feasible to mine in other locations. Although many additional deposits of REEs have been discovered - and their economic feasibility debated by many countries - it will continue to become important to find new deposits. Private funding will continue to be focused on junior exploration companies in an effort to increase known reserves.
The Geology of Rare Earth Elements .
The estimated average concentration of the rare earth elements in the Earth's crust, which ranges from around 150 to 220 parts per million, exceeds that of many other metals that are mined on an industrial scale, such as copper (55 parts per million) and zinc (70 parts per million). Unlike most commercially mined base and precious metals, however, rare earth elements are rarely concentrated into mineable ore deposits.
The principal concentrations of rare earth elements are associated with uncommon varieties of igneous rocks, namely alkaline rocks and carbonatites. Potentially useful concentrations of REE-bearing minerals are also found in placer deposits, residual deposits formed from deep weathering of igneous rocks, pegmatites, iron-oxide copper-gold deposits, and marine phosphates (Table 2).
Afghanistan, officially the Islamic Republic of Afghanistan, is a landlocked country at the crossroads of Central and South Asia. Afghanistan is bordered by Pakistan to the east and south; Iran to the west; Turkmenistan, Uzbekistan, and Tajikistan to the north; and China to the northeast. Occupying 652,000 square kilometers (252,000 sq mi), it is a mountainous country with plains in the north and southwest. Kabul is the capital and largest city. The population is around 32 million, composed mostly of ethnic Pashtuns, Tajiks, Hazaras, and Uzbeks.
In the late 19th century, Afghanistan became a buffer state in the "Great Game" between British India and the Russian Empire. In the First Anglo-Afghan War, the British East India Company seized control of Afghanistan briefly, but following the Third Anglo-Afghan War in 1919 the country was free of foreign influence, eventually becoming a monarchy under Amanullah Khan, until almost 50 years later when Zahir Shah was overthrown and a republic was established. In 1978, after a second coup, Afghanistan first became a socialist state, evoking the Soviet–Afghan War in the 1980s against mujahideen rebels. By 1996, most of the country was captured by the Islamic fundamentalist Taliban, who ruled as a totalitarian regime for over five years; they were removed from power after the US invasion in 2001 but still control a significant portion of the country. The ongoing war between the government and the Taliban has contributed to the perpetuation of Afghanistan's problematic human rights record including complications of women's rights, with numerous abuses committed by both sides, such as the killing of civilians.
Afghanistan is a unitary presidential Islamic republic. The country has high levels of terrorism, poverty, child malnutrition, and corruption. It is a member of the United Nations, the Organisation of Islamic Cooperation, the South Asian Association for Regional Cooperation, the Group of 77, the Economic Cooperation Organization, and the Non-Aligned Movement. Afghanistan's economy is the world's 96th largest, with a gross domestic product (GDP) of $72.9 billion by purchasing power parity; the country fares much worse in terms of per-capita GDP (PPP), ranking 169th out of 186 countries as of 2018.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.