Nickel sulfide

Nickel sulfide Chemische Eigenschaften,Einsatz,Produktion Methoden

• Chemische Eigenschaften

  The mineral millerite is brittle; hardness, 3–3.5; specific gravity, 5.48–5.52; luster, metallic; color, brass-yellow, often with an iridescent tarnish.

• Physikalische Eigenschaften

  Trigonal crystalline solid or amorphous powder; mineral millerite has a yellow metallic luster; color varies from yellow to brownish black; density 5.30 to 6.65 g/cm³; exhibits three allotropic modifications: (1) the acid-soluble amorphous alpha form obtained from nickel salt solution by precipitation with ammonium sulfide, (2) the alpha form rapidly transforms to a crystalline beta form as a brown colloidal dispersion upon exposure to air, and (3) a rhombohedral gamma modification found native as mineral millerite, which also can be prepared artificially under certain conditions.
  Gamma-NiS slowly converts to beta-NiS in solution. Beta form probably is richer in sulfur than alpha and gamma modifications and therefore they could have varying stoichiometric compositions.
  Nickel sulfide melts at 797°C and is insoluble in water (3.6 mg/L at 18°C; soluble in concentrated nitric acid and potassium hydrogen sulfide solution; slightly soluble in alcohol.

• Occurrence

  Nickel sulfide occurs in nature as mineral millerite. Its principal use is as a source material for making nickel metal.

• Verwenden

  MILLERITE is used as an ore of nickel. Millerite was named for the English mineralogist, W.H. Miller.

• synthetische

  Nickel sulfide is mined directly from natural deposits. Also, it can be prepared in the laboratory by precipitation from an aqueous solution of a nickel salt with ammonium sulfide, (NH₄)₂S, or by precipitation from an acetic acid solution with hydrogen sulfide. While the aqueous solution method yields an amorphous product (alpha-NiS) which rapidly changes on exposure to air and contact with the solution to a brown crystalline sulfide (beta-NiS), the acid solution method forms only crystalline beta-NiS.
  Nickel sulfide also can be prepared by reacting nickel powder with molten sulfur.