PROCESS FOR THE PREPARATION OF SULPHIDE-FREE ALKALI LIQUOR

摘要

A process is disclosed for the preparation of an essentially sulphide-free alkali liquor starting from an alkali sulphide source. The alkali sulphide source is reacted in alkaline medium with copper (II) oxide and/or copper (I) oxide, optionally with the addition of water, in a mole ratio of oxide to sulphide (calculated as alkali sulphide) (charging) of at least 0.9. The mixture obtained is allowed to react at a temperature of from 30 to 130.degree.C to form hydroxide in an amount equivalent to the amount of sulphide and to precipitate a solid phase consisting essentially of copper (I) sulphide, copper (II) sulphide ox a mixture thereof. Thereafter, the solid phase is separated in a manner known per se to obtain an essentially sulphide-free alkali liquor. The reaction time of the precipitation reaction is adjusted with regard to the charging and temperature selected so that the residual concentration of copper ions in the final alkali liquor is below 1 mmole/litre.