由詹姆斯B. Hedrick

钍是一种柔软,非常韧性,银灰色,厚重,金属元素的神奇系列元素。它由化学符号TH或同位素符号TH232表示。钍金属具有非常高的熔点,而也称为梭坡的氧化物具有最高氧化物的熔点。Th232是钍的四种天然存在的同位素中最丰富的。TH232发出放射性α颗粒,并且具有1.405 x 1010年的长期半衰期。TH232崩解系列的女儿产品产生alpha,beta和伽玛排放。大多数崩解系列的产品具有相对较短的半衰期,范围从5.75秒到0.145秒。TH232系列的最终衰减产品是稳定的同位素PB208。Thorium的其他天然存在同位素,TH228,TH230和TH234,分别为1.9116岁,75,380岁和241天。

瑞典化学家和矿物学家Jons Jakob Berzelius于1828年发现了钍。他在雷神之后被命名为洛杉矶,古代诺斯雷霆之神。Berzelius孤立来自黑硅酸盐矿物的元素从Lovo海岛附近Brevig,挪威。随后,源自梭罗的黑色矿物被命名为钍。由Marie Curie和C.G,Carium在1898年独立发现了钍的放射性。施密特。

Thorium is the 39th most abundant of the 78 common elements in the Earth’s crust, at 7.2 parts per million. It is about three times more abundant than uranium and is associated with uranium in igneous rock As the primary thorium minerals are more resistant to geochemical and physical weathering, the thorium/uranium ratio in sedimentary rock is typically higher than its igneous source rock. Thorium occurs in several minerals, the most common being monazite and thorite.

根据美国地质调查(USGS),1997年国内精炼钍产品的消费量增加。据估计,国内行业使用的钍金属和化合物的价值约为300,000美元。钍产量主要来自稀土 - 钍 - 磷矿矿物,单一矿物,加工钛和锆矿物或锡矿物的重型矿物砂。在稀土的加工过程中,从单济岩生产钍化合物。只消耗了产生的一小部分钍;大多数被丢弃为浪费。主要的Monazite的国家是巴西,中国,印度,马来西亚和斯里兰卡。基本上,国内工业使用的所有钍化合物,金属和合金都来自于从美国政府股票销售的进口,公司股票或材料。

相对于稀土而言,对钍的需求有限,继续造成全世界钍化合物和残留物的供应过剩。大多数主要的稀土加工厂都将原料改为不含钍的中间化合物。多余的钍不是指定用于商业用途,而是作为放射性废物处理或储存起来作为核燃料或其他用途。非能源的主要用途已从耐火材料应用转向电焊条和照明。

与钍的天然放射性有关的问题对那些从事钍的开采、加工、制造和使用的公司来说是一个巨大的成本。遵守环境法规的成本增加、潜在的法律责任以及购买储存和废物处理空间的成本是阻碍其商业用途的主要因素。据业内人士透露,与钍的天然放射性有关的健康问题并不是改用非放射性替代材料的重要因素。

立法和政府计划

The calendar year 1997 included parts of the U.S. Government fiscal years (October 1 to September 30) 1997 and 1998. Public Law 104-201, the National Defense Authorization Act for Fiscal Year 1997, was enacted on September, 23, 1997. It did not change the previous authorization for the disposal of all stocks of thorium nitrate in excess of the National Defense Stockpile (NDS) goal of 272,155 kilograms (600,000 pounds). The National Defense Authorization Act for Fiscal Year 1998, Public Law 105-85, also known as the “Strategic and Critical Stock Piling Act,” was enacted on November 18,1997. The revised annual material plan proposed the disposal of up to 453,592 kilograms (1,000,000 pounds) of thorium nitrate in fiscal year 1998. It did not change previous authorizations for the disposal of 2,946,185 kilograms (6,495,225 pounds) of thorium nitrate classified as excess to goal.

生产

Domestic mine production data for thorium-bearing monazite were developed by the USGS from a voluntary survey of U. S. operations entitled “Thorium.” The one mine to which a survey form was sent responded. Thorium was not produced in the United States in 1997, however, the mine that had previously produced thorium-bearing monazite continued to operate and maintained capacity on standby. Monazite was last produced in the United States in 1994.

基本上,国内工业使用的所有钍合金和化合物都来自于从美国政府库存中销售的进口,公司股票或材料。国内公司处理或制作各种形式的钍,用于陶瓷,镁 - 合金,耐火材料和焊接电极。

消费

通过调查各种处理器和制造商,评估进出口数据,分析政府储存货物,开发了国内钍消费的统计数据。(见表1.)

国内钍生产商报告了1997年消费了13.0公吨氧化钍等同物,从1996年的4.92吨增加。该增加主要是催化剂应用中钍需求增加的结果。非整体用途本质上占所有消费量。

氧化钍(梭坡)具有3,300℃的所有二元金属氧化物的最高熔点。此属性有助于其在几种耐火应用程序中。高温用途是陶瓷部件,投资模具和坩埚。

硝酸钍用于制造白炽灯“露营”灯笼的幔中,包括天然气灯和油灯。钍幔提供一种强烈的白光,通过少量加入铈向黄色区域调节。由于开发了合适​​的无钍替代品,横梁罩未在国内生产。
硝酸钍也用于生产挖掘钨焊接电极。横梁钨焊接电极用于加入不锈钢,镍合金和需要连续且稳定的电弧的其他合金以实现精密焊接。

硝酸盐形式也被用来生产钍钨元素用于磁控管的负极。之所以使用钍,是因为它在真空中加热时能够在相对较低的温度下发射电子。磁控管被用来发射微波频率的电子,在微波炉和雷达系统中加热食物,用于跟踪飞机和天气状况。

Thorium was used in other applications as catalysts, electron emitting-tubes, elements in special use light bulbs, fuel cell elements, high-refractivity glass, photo conductive films, radiation detectors, and target materials for X-ray tubes.

In metallurgical applications, thorium was alloyed primarily with magnesium. Thorium metal has a high melting temperature of 1,750°C and a boiling point of about 4,790°C. Magnesium-thorium alloys used by the aerospace industry are lightweight and have high strength and excellent creep resistance at elevated temperatures. Thorium-free magnesium alloys with similar properties have been developed and are expected to replace most of the thorium-magnesium alloys presently used. Small quantities of thorium were used in dispersion-hardened alloys for high-strength, high-temperature applications.

钍在钍-232/铀-233燃料循环中用作核燃料。没有任何国外或国内的商业反应堆在使用这种燃料循环。由于目前廉价铀的供应,钍作为核燃料的使用预计不会增加。

股票

1997年12月31日,NDS中硝酸盐钍的政府股票为3,216,828千克(7,091,891磅)。该NDS于1997年运送了1,724公斤(3,800磅)的废物处置研究。NDS库存包括273,181千克(602,262磅)的硝酸钍分配以满足NDS目标要求,2,943,646千克(6,489,629磅)分类为逾期目标。年内没有硝酸钍销售。

美国能源部(DOE)年底的库存量为53.5万公斤,相当于金属和各种化合物中所含的氧化钍。能源部的承包商Fernald环境恢复管理公司(Fernald Environmental Restoration Management Company)是Huor Daniel的Fernald的子公司,在1997年运送了140000公斤氧化钍,Fernald还运送了矿石中所含的估计4200公斤氧化钍当量到废物处理厂。

价格

Monazite浓缩物的价格,通常以最少55%的稀土氧化物出售,包括在美国美元,并以美国进口数据所引用的洛尼亚,自由的(F.O.B.)。每吨400美元。1997年的Monazite价格从前几年的价格增加,澳大利亚美元(A $)转换为244美元(金属公告,1997)。1997年含有稀土氧化物的Monazite的价格以每公斤0.73美元出售。

Thorium oxide prices quoted by Rhone-Poulenc Basic Chemicals Co. (Rhodia as of January 1, 1998) decreased slightly or were unchanged in 1997. At yearend 1997, thorium oxide prices per kilogram f.o.b. Shelton, CT, were $82.50 for 99.9% purity and $107.25 per kilogram for 99.99% purity.

由于公司股票的耗尽,由Reade Manufturing Co.,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst,Lakehurst。

世界评论

由于工业消费者对潜在负债的担忧表示关切,核对废物处理场所的持续性负债表达担忧,钍需求持续持续抑郁。

外表

Nonenergy uses for thorium in the United States have decreased substantially over the past 7 years. Domestic demand is forecast to remain at current depressed levels unless low-cost technology is developed to dispose of residues. Manufacturers have successfully developed acceptable substitutes for thorium-containing incandescent lamp mantles, paint and coating evaporation materials, magnesium alloys, ceramics, and investment molds. The traditionally small markets for thorium compounds, welding electrodes, and lighting, are expected to remain the leading consumers of thorium compounds through the end of the millennium. Thorium’s potential for growth in nonenergy applications is limited by its natural radioactivity. Its greatest potential exists in energy applications as a nuclear fuel or subatomic fuel in an industry that accepts radioactivity. In the long term, high disposal costs, increasingly stringent regulations, and public concerns related to thorium’s natural radioactivity are expected to continue to depress its future use.

Reference Cited

金属公报,1996,有色金属矿石:金属公报[伦敦]不,。8141,12月31日,第25页。

信息来源

U.S. Geological Survey Publications

霍里姆。年度矿业行业调查。
Thorium. Ch. In Mineral Commodity Summaries, annual.
Thorium. Ch. In Minerals Yearbook.
Nuclear Fuels. Ch. In United States minerla resources, U.S.
地质调查专业论文8201973。

其他

Uranium Industry Annual 1997, U.S. Department of Energy.
Thorium. Ch. In Minerla Facts and Problems, U.S. Bureau of
矿山公告675,1985。

thorium-statistics-1

thorium-statistics-2

thorium-statistics-3

美国1998年地质调查钍总结

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