国产日韩亚洲大尺度高清,国产高潮流白浆喷水免费网站,97久久综合区小说区图片区,精品国产免费第一区二区三区

首頁   新聞資訊   供應求購   鎢的知識   人才招聘  生產設備   輔助材料   業界知識   繁體中文   英語語版   日本語版   論壇
鎢報價:  硬質合金 高比重合金 三氧化鎢 純鎢產品 鎢銅產品 鎢制品 鎢礦類 鎢粉末  難熔金屬:       稀土  會員服務
新聞首頁
國際資訊
國內資訊
會員新聞
鎢業新聞
統計數據
粉末冶金
鎢制品、軍事與核能
中鎢在線信息服務
供應求購
新聞搜索
相 關 文 章
沒有相關文章
熱圖新聞

重慶首現蛇紋石 礦產資源錦

煙草專賣局:開查13品牌香

四季度行業投資:小金屬品
Nature and sources of thorium
作者:yu    文章來源:網絡轉載    更新時間:2011-11-11 15:00:06

Nature and sources of thorium


Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius, who named it after Thor, the Norse god of thunder. It is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium. Soil commonly contains an average of around 6 parts per million (ppm) of thorium.

Thorium exists in nature in a single isotopic form - Th-232 - which decays very slowly (its half-life is about three times the age of the Earth). The decay chains of natural thorium and uranium give rise to minute traces of Th-228, Th-230 and Th-234, but the presence of these in mass terms is negligible.

When pure, thorium is a silvery white metal that retains its lustre for several months. However, when it is contaminated with the oxide, thorium slowly tarnishes in air, becoming grey and eventually black. Thorium oxide (ThO2), also called thoria, has one of the highest melting points of all oxides (3300°C). When heated in air, thorium metal turnings ignite and burn brilliantly with a white light. Because of these properties, thorium has found applications in light bulb elements, lantern mantles, arc-light lamps, welding electrodes and heat-resistant ceramics. Glass containing thorium oxide has a high refractive index and dispersion and is used in high quality lenses for cameras and scientific instruments.

The most common source of thorium is the rare earth phosphate mineral, monazite, which contains up to about 12% thorium phosphate, but 6-7% on average. Monazite is found in igneous and other rocks but the richest concentrations are in placer deposits, concentrated by wave and current action with other heavy minerals. World monazite resources are estimated to be about 12 million tonnes, two-thirds of which are in heavy mineral sands deposits on the south and east coasts of India. There are substantial deposits in several other countries. Thorium recovery from monazite usually involves leaching with sodium hydroxide at 140°C followed by a complex process to precipitate pure ThO2.

Thorite (ThSiO4) is another common mineral. A large vein deposit of thorium and rare earth metals is in Idaho.

The 2007 IAEA-NEA publication Uranium 2007: Resources, Production and Demand (often referred to as the 'Red Book') gives a figure of 4.4 million tonnes of total known and estimated resources, but this excludes data from much of the world. Data for reasonably assured and inferred resources recoverable at a cost of $80/kg Th or less are given in the table below. Some of the figures are based on assumptions and surrogate data for mineral sands, not direct geological data in the same way as most mineral resources.


免責聲明:上文僅代表作者或發布者觀點,與本站無關。本站并無義務對其原創性及內容加以證實。對本文全部或者部分內容(文字或圖片)的真實性、完整性本站不作任何保證或承諾,請讀者參考時自行核實相關內容。本站制作、轉載、同意會員發布上述內容僅出于傳遞更多信息之目的,但不表明本站認可、同意或贊同其觀點。上述內容僅供參考,不構成投資決策之建議;投資者據此操作,風險自擔。如對上述內容有任何異議,請聯系相關作者或與本站站長聯系,本站將盡可能協助處理有關事宜。謝謝訪問與合作!  中鎢在線采集制作.


文章錄入:yu    責任編輯:yu 
  • 上一篇文章:

  • 下一篇文章: 沒有了
  • 【字體: 】【發表評論】【加入收藏】【告訴好友】【打印此文】【關閉窗口
    合作伙伴
    中鎢在線 中鎢莆田公司 高比重網 中國鉬網 硬質合金大全 中國鎢絲網 中國飛鏢網 鎢合金鎮紙網
    純鎢制品網 中國鎢粉網 鎢棒材 加熱子網 鎢合金航空工具 空間租賃 飛鏢網購 鎢鉬百科
    聊天轉盤 廈門市中醫藥促協會 金屬報價 鎢鋼首飾 鎢合金魚墜 鎢銅合金 飛鏢商城 廈門中鎢
    鎢制品目錄

    |加入收藏|關于鎢協|聯系我們|友情連接|網站招聘|網站業務|


    Copyright © 2000 - 2009 中國鎢業新聞網 All Rights Reserved
    建議使用:1024x768分辨率,16位以上顏色、IE5.5以上版本瀏覽本站
    (本站信息僅提供參考,請注意投資風險!)
    本站部分內容屬轉載!如果侵犯了您的版權請來信告知,我們將會立即更改。