The discovery and development of a number of large and super large rare earth deposits in the world's major rare earth resource countries are the main sources of rare earth resources in the world. Among them, in addition to foreign countries, China has proven reserves of rare earth resources of 43 million tons, accounting for 43% of the world's total reserves (China's rare earth resources provided by the China Rare Earth Association's proven reserves of 5200 tons, accounting for In addition to the world's rare earth reserves of more than 50%, the United States has 13 million tons of rare earth reserves, making it the second largest rare earth country in the world. Some of the more typical deposits are: China's Mongolian Bayan Obo iron , antimony , rare earth deposits; Sichuan's Suiningping type single fluorocarbon antimony deposit; southern weathered leaching type rare earth deposit; Australia's Verde mountain carbonate rock weathering crust Deposit; the monazite sand deposit in the east and west coast of Australia; the Manton Pass Carbonate fluorocarbon strontium deposit in the United States; the rare earth deposit of the carbonated weathering crust in the Arabian and Zessra, Brazil; Tomtor, Russia Carbonate weathering crust rare earth deposit, Xibin Phosphorite rare earth deposit; Vietnam Maosai carbonate rock rare earth deposit. Its rare earth resources are all over 1 million tons, some reach 10 million tons, and some more than 100 million tons, which constitute the main body of the world's rare earth resources.
According to relevant statistics, China's rare earth resources accounted for 74% of the world's total in the 1970s, and fell to 69% in the 1980s, and fell to 45% in the late 1990s, mainly in Australia, Russia, Canada, Brazil, In the past 20 years, Vietnam and other countries have made significant progress in the exploration and research of rare earth resources. They have discovered a number of large-super large rare earth deposits, such as Mount Verde in Australia, Tomtor in Russia, and St. Honor in Canada. Lei, Vietnam's Maosai and other rare earth deposits. However, China's rare earth resources still occupy the first place in the world, and the resource potential is very large. Therefore, there is reason to believe that the status of China's rare earth resource power will not change for a long time to come.
The US reserves of rare earth resources are 13 million tons, accounting for about 13% of the world's total reserves. U.S. rare earth resources are bastnasite and monazite, when sorting other additional minerals recovered as a byproduct rare earth minerals dilute black gold ore, gadolinite and xenotime. The Mountain Pass Mine, located in San Bernardino County, California, is the world's largest single fluorocarbon antimony ore with a rare earth grade of 5% to 10% REO and a reserve of 4.3 million tons. The US monazite resources include the southeast coast sand mine, the northwest riverbed sand deposit, and the Atlantic continental shelf sedimentary deposit. Located at the southern tip of Princes Wales Island in the southernmost part of the Alaska Peninsula, the Poken Mountain rare earth ore reserves are 6.8 million tons, and the rare earth oxide grade is 0.264%, of which about one-third of the cerium oxide has been processed and extracted.
The reserves of rare earth mineral resources in Russia and other CIS countries are also very large. According to estimates by the US Geological Survey in January 1993, the reserves of rare earths are about 19 million tons, accounting for 19% of the world's total reserves. The proportion of Russian rare earth reserves in it is still unclear. Russia's rare earth minerals mainly include titanium citrate (such as strontium and barium perovskite), apatite and fluorocarbonate, etc., mainly recovering rare earth resources from apatite ore.
Australia is a large country of monazite resources. In recent years, several large rare earth mines have been discovered. The proven rare earth reserves in the Weld Mountain are 1.7 million tons. The rare earth resource reserves are more than 10 times higher than the statistics in the 1980s, and the total reserves are 5.2 million tons.
India's rare earth resources are mainly monazite, distributed in coastal sand mines and inland sand mines. The total reserves of rare earths are about 1.1 million tons, accounting for 1% of the world's reserves. In 1993, the atomic minerals division of the Ministry of Atomic Energy of India estimated that the total reserves of monazite was 4.56 million tons. The famous monazite mining area is the Travanco deposit on the southwest coast of Chawala and Mana Van Laculic. From 1911 to 1945, the supply of monazite was half of the world, and it is still an important rare earth producing area. . In 1958, when the exploration of uranium and thorium resources in Bihar Ranchi plateau found a monazite and ilmenite deposits, a large scale, is reported to have 3500 tons per square mile monazite, but currently untapped.
Canada mainly recovers rare earths from uranium mining. The uranium mine is located in the Bryandri-Ellit area of ​​Ontario. The uranium mine consists of asphalt uranium, titanium uranium, monazite and xenotime. The rare earth is recovered as a by-product. In addition, there are pyrochlore mines in the Oka area of ​​Quebec, which is also a large potential rare earth resource. The Strenci mines in Newfoundland and Labrador contain strontium and heavy rare earths and are preparing for mining.
South Africa is the most important monazite producer in Africa. The apatite mine in Sturkampskra, Cape Province, is accompanied by monazite and is the only single vein-type monazite rare earth mine in the world. In addition, rare earths are found in the coastal sand mines of Chaz Bay on the east coast, and monazite and bastnasite are also associated with the Buffalo fluorite mine, and mining and recycling plans are being developed.
Brazil is the oldest country producing rare earths. It began to export monazite to Germany in 1884 and was once famous in the world. Brazil's monazite resources are mainly concentrated on the eastern coast, from Rio de Janeiro to Fortaleza in the north, with a length of about 643 kilometers. The deposit is large and is selected by Nuclear Energy and Monazite United Co., Ltd. In recent years, important rare earth deposits including rouge lead uranium ore, bastnasite and brownstone have been found in Morudu Ferru, and the rare earth oxide grade is 4%.
The seamless steel pipe is made by perforating the whole round steel, and the steel pipe without weld seam on the surface. It is mainly used as high-precision structural steel pipes for petrochemical industry, boiler pipes, automobiles and aviation.
Seamless tubing can be made from any of several alloys and metals, such as carbon steel, stainless steel, molybdenum, or tungsten. Seamless pipes are used in those industrial applications that require the highest safety requirements. To produce seamless steel pipes, the solid block is pierced with a piercing plug before the pipe is drawn to the desired size.
Some of the differences between seamless and welded pipes are:
Seamless pipes are extruded and drawn from billets, while welded pipes are produced from roll formed and welded strips.
Due to the higher range of security offered by seamless pipe, it is more expensive than welded pipe.
Seamless pipes are available in relatively short lengths, while welded pipes can be manufactured in longer continuous lengths.
Seamless pipe generally does not show any signs of corrosion until and unless it is subjected to a highly corrosive environment, whereas in welded pipe the welded area is more susceptible to corrosion attack.
The welded area is considered to be inhomogeneous, so it exhibits different ductility and lower corrosion resistance, as well as larger dimensional changes. Seamless pipes eliminate any such problems and thus offer high corrosion resistance.
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