Recovery of Nickel from Nickel Ammonium Carbonate Systems (Patent No: 892478)

Inventor: Evans, David J.I.

Location: Edmonton

Comments: N/A

Description: The embodiments of the invention in which an exclusive property or privilege is claimeds are defined as follows:

1. In the method for the production of nickel from nickel bearing aqueous ammoniacal ammonium carbonate systems containing impurities including at least one of zinc, magnesium and manganese in which the system is reacted with hydrogen at elevated temperature and pressure to precipitate nickel in elemental form, the improvement which enables production of nickel in elemental form substantially free from contamination by said impurities which comprises adjusting the sulphate ion content of the system prior to said reaction with hydrogen to provide at least the stoichiometric amount of sulphate ions required to combine with the said metal contaminants in the system as soluble sulphates.

2. The method according to claim 1 wherein the sulphate ion content is adjusted by the addition to the system prior to the reduction step of a sulphate compound which will dissolve in the system and form soluble sulphates with the contaminant metals but which will not add cations to the system which will precipitate with and contaminate the nickel in the subsequent hydrogen reduction step.

3. The method according to claim 2 wherein the sulphate compound is a member selected from the group consisting of nickel sulphate, sulphuric acid and ammonium sulphate.

4. The method according to claims 1, 2 or 3 wherein the sulphate ion content of the system is adjusted to the equivalent of between about land 3 g.p.l. of sulphur.

5. The method according to claim 1 wherein the sulphate ion content is adjusted by providing oxidizable sulphur values in the system and, prior to said reaction with hydrogen, reacting the oxidizable sulphur containing system at an elevated temperature with free oxygen bearing gas to convert said sulphur values to sulphate form.

6. The method according to claim 5 wherein the oxidizable sulphur values are provided by addition of elemental sulphur.

7. The method according to claim 5 including the additional step of adjusting the ammonia content of the system prior to reaction with hydrogen such that there is at least sufficient ammonia therein to form ammonium sulphate with any sulphate ions present in the system in excess of those required to satisfy the stoichiometric requirements of said metal impurities as sulphate.