A Study on Precipitation Recovery of Molybdenum from Aqueous Solutions of Ammonium Chloride

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  • NIINAE Masakazu
    Department of Environmental Science and Engineering, Yamaguchi University
  • SUZUKI Tasuma
    Department of Environmental Science and Engineering, Yamaguchi University
  • FUJI Akiko
    Department of Environmental Science and Engineering, Yamaguchi University
  • MATSUNAGA Nanae
    Department of Sustainable Environmental Engineering, Yamaguchi University
  • SHIBATA Junji
    Department of Chemical, Energy and Environmental Engineering, Kansai University

Bibliographic Information

Other Title
  • 塩化アンモニウム水溶液からのモリブデンの晶析に関する研究
  • エンカ アンモニウム スイヨウエキ カラ ノ モリブデン ノ ショウセキ ニ カンスル ケンキュウ

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Description

Catalysts are widely used in petroleum refining and chemical industries. Hydrodesulphurization (HDS) catalysts account for about one third of the total worldwide catalyst consumption. Spent HDS catalysts contain rare metals such as molybdenum, vanadium, nickel and cobalt on an alumina carrier. Among secondary resources, spent HDS catalysts are regarded the most important catalysts for recycling these metals due to not only their large amounts and economic values, but also the environmental concerns if disposed off. In most cases, spent catalysts are treated with hydrometallurgical leaching processes such as caustic leaching and acid leaching with roasting as a pre-treatment step. In the alkaline leaching processes, most of the molybdenum and vanadium are selectively leached over aluminum, nickel and cobalt. Vanadium can be separated from molybdenum with a two stage process based on solvent extraction and precipitation stripping. Molybdenum and vanadium are simultaneously extracted with tri-n-octylamine (TOA) at around pH 4 followed by stripping of molybdenum and vanadium with ammonium salt solutions. In the stripping process, vanadium alone is precipitated as ammonium salts of tetraammonium disodium decavanadate decahydrate at pH > 8.<br> In the present study, precipitation method was carried out to recovery of molybdenum from aqueous solutions of ammonium chloride. Molybdenum could be precipitated as tetraammonium octamolybdate pentahydrate with ammonium chloride at the pH below 4 and the pH region of precipitation increased with increase of temperature. And also, the precipitation of molybdenum with barium chloride and calcium chloride was also investigated.<br>

Journal

  • Resources Processing

    Resources Processing 60 (3), 151-156, 2013

    The Resources Processing Society of Japan

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