nickel

A chemical element. Chemical symbol Ni, atomic number 28, atomic weight 58.69, belongs to the VIII group of the periodic table. The ancient Egyptians, China and Babylonians all used meteorites with high nickel content to make artifacts, and the white copper produced in Yunnan in ancient China had high nickel content. 175 1 year, Swedish A.F. Krohns Ted reduced red nickel ore with charcoal to make metallic nickel. Its English name comes from German Kupfernickel, which means fake copper. The content of nickel in the crust is 0.0 18%, and the main minerals are nickel pyrite [(Ni, Fe)9s 8]], silicomagnesite [(Ni, Mg) SiO 3 NH2O]], goethite or chalcopyrite (NiS) and hematite (NiAs). Submarine manganese nodules contain a large amount of nickel, which is an important nickel prospect resource.

Nickel is a silvery white metal with melting point 1455℃, boiling point 2730℃ and density of 8.90g/cm3. It is ferromagnetic and malleable, and can conduct electricity and heat. At room temperature, a dense oxide film is formed on the surface of nickel in humid air, which can not only prevent it from being oxidized, but also resist the corrosion of alkali and salt solution. Bulk nickel will not burn, fine nickel wires will burn, and special fine porous nickel particles will spontaneously ignite in the air. When heated, nickel reacts violently with oxygen, sulfur, chlorine and bromine. Fine powder nickel can absorb a lot of hydrogen when heated. Nickel can be slowly dissolved in dilute hydrochloric acid, dilute sulfuric acid and dilute nitric acid, but its surface is passivated in fuming nitric acid. The oxidation states of nickel are-1,+1, +2, +3 and +4. Among simple compounds, +2 valence is the most stable, and +3 valence is the oxidant. Nickel oxide includes NiO and Ni2O3. Nickel hydroxide [Ni (OH) 2] is a strong base, slightly soluble in water and easily soluble in acid. Nickel sulfate (niso 4 4) can react with alkali metal sulfate to produce alum Ni (SO 4) 2 6H2O (MI is alkali metal ion). +2 valence nickel ions can form coordination compounds. Under pressure, nickel and carbon monoxide can form nickel tetracarbonyl [Ni (Co) 4], which will be decomposed into metallic nickel and carbon monoxide after heating.

The preparation methods of nickel are as follows: ① Electrolysis. The enriched sulfide ore is roasted into oxide, reduced to crude nickel with carbon, and then electrolyzed to obtain pure nickel. ② Carbonylation method. Nickel sulfide reacts with carbon monoxide to generate nickel tetracarbonyl, which is decomposed after heating to obtain high-purity metallic nickel. ③ Hydrogen reduction method. Nickel metal can be obtained by reducing nickel oxide with hydrogen. Nickel is mainly used to make stainless steel and corrosion-resistant alloys. Nickel is also widely used for nickel plating. Nickel-copper alloy is used in resistance alloy, heat exchanger and condenser tube. Nickel-chromium-iron alloy is used to make steam turbines and electric heating wires. Nickel is used as a hydrogenation catalyst in the chemical industry.