PROCESS FOR THE PREPARATION OF SULPHIDE-FREE ALKALI LIQUOR

摘要

ABSTRACT OF THE DISCLOSUREA process is disclosed for the preparation of anessentially sulphide-free alkali liquor starting from analkali sulphide source. The alkali sulphide source isreacted in alkaline medium with copper (II) oxide and/orcopper (I) oxide, optionally with the addition of water,in a mole ratio of oxide to sulphide (calculated as alkalisulphide) (charging) of at least 0.9. The mixtureobtained is allowed to react at a temperature of from 30to 130°C to form hydroxide in an amount equivalent to theamount of sulphide and to precipitate a solid phaseconsisting essentially of copper (I) sulphide, copper (II)sulphide ox a mixture thereof. Thereafter, the solidphase is separated in a manner known per se to obtain anessentially sulphide-free alkali liquor. The reactiontime of the precipitation reaction is adjusted with regardto the charging and temperature selected so that theresidual concentration of copper ions in the final alkaliliquor is below 1 mmole/litre.