What is nickel carbonate?

Nickel carbonate, rhombohedral light green crystals, decompose above 300℃. Dissolved in ammonia and dilute acid, insoluble in water, made by the reaction of alkali metal carbonate and nickel sulfate, used in electroplating, ceramic ware coloring and glazing agent, etc.

Nickel carbonate is a mixture of one or several inorganic compounds containing nickel and carbonate. The most industrially important form of nickel carbonate is alkali nickel carbonate, with the chemical formula Ni4CO3(OH)6(H2O)4. Common simpler compositions of nickel carbonate are NiCO3, and its hexahydrate. All paramagnetic green solids contain Ni2+ ions. Alkaline nickel carbonate is an intermediate product of the wet extraction of nickel from minerals and has applications in the electroplating of nickel.

Physicochemical properties of nickel carbonate

[ Boiling point ]: 333.6ºC at 760 mmHg

[ Molecular formula ]: NiCO₃

[ Molecular weight ]: 118.702

[ Flash point ]: 169.8ºC

[ Exact mass ]: 117.920090

[ PSA ]: 63.19000

[ Appearance ]: Light green powder

[Storage conditions]:

Room temperature, light, ventilated and dry place, sealed and kept in iron barrel lined with plastic bag, net weight 50kg, 40kg in wooden barrel, or 50g in one bag, 100 bags in one iron barrel. It should be stored in a cool, dry warehouse, keep dry when transporting, prevent from heat, not to be stored and transported with acids.  

[ Stability ]:

Stable at room temperature and pressure. Decompose into CO2 and NiO when heated to 400℃.

Chemical index of nickel carbonate

Nickel (NI) /% > 40

Hydrochloric acid insoluble matter /% <0.02

Heavy metal (in Cu) /% <0.01

Chloride (in Cl) /% <0.01

Sulfate (in SO2) /% <0.05

Iron (Fe) /% <0.002

Cobalt (Co) /% <0.3

Zinc (Zn) /% <0.05

Ammonium sulfide non-precipitates /% <0.7

Structure and reactions of nickel carbonate

NiCO3 structure resembles calcite, with nickel located in an octahedral structure.

Nickel carbonate hydrolyzes on contact with water, which produces hydrated nickel ions [Ni(H2O)6]2+ and releases water and carbon dioxide.

Calcination (heating to drive off carbon dioxide and water), will cause nickel carbonate to decompose, producing carbon dioxide and nickel oxide. The anhydrous nickel carbonate used here NiCO3 → NiO + CO2

Nickel carbonate hydrate can be prepared by electrolysis of nickel sulfate with sodium carbonate: 4 Ni2+ + Na2CO3 + 6 OH- + 4 H2O → Ni4CO3(OH)6(H2O)4 + 2 Na+

Nickel carbonate hydrate can already be prepared as nickel and carbon dioxide by electrolytic oxidation: Ni + O + CO2 + 6 H2O → NiCO3(H2O)4

How to preparation nickel carbonate

1. Prepare aqueous NaHCO3 solution saturated with CO2, add it to a flask containing aqueous NiCl2 or Ni(NO3)2, stopper tightly to prevent CO2 from escaping and keep the solution at low temperature. The resulting precipitate was filtered and washed, noting that this was done at low temperature, and then dried to obtain the NiCO3 product. The product obtained by this method is not pure and will contain some sodium salt.

2. Electrolysis of carbonic acid water (i.e. CO2 saturated aqueous solution) with a nickel electrode. Cover the electrolytic tank with a lid made of insulating material, hang three nickel plates on the lid, two of which are placed at the two ends of the tank (cathode) and the other one is placed in the center (anode), add pure water to 2.5cm from the top edge of the tank, pass pure carbon dioxide gas, cool the tank with running water, pass a current of 2~2.2A between the two poles, then generate nickel carbonate hexahydrate, which is deposited at the bottom of the tank, and the precipitate is Filter and dry at 100°C to obtain nickel carbonate.

3. Nickel chloride solution heated to boiling is added to boiling excess sodium carbonate solution for reaction: the precipitated precipitate is filtered, washed with hot water until the Cl- ion content is qualified, shaken dry and dried at not more than 40℃, then washed with hot water until the Cl- ion content is qualified, shaken dry and dried at 25-30℃.

Application of Nickel Carbonate

It is widely used in electroplating, catalyst, pigment and other industries. High quality alkaline nickel carbonate can also be used as an intermediate in the production of nickel oxide, nickel powder and other organic nickel salts.