Patent ID: 7371356
Filing Date: 2008-05-13
Classification: C01F,C01P,C09C

Abstract:
1. A process for the preparation of calcium carbonate with high brightness by reductive bleaching by means of one sulfinic and/or sulfonic acid derivative, which comprises treating calcium carbonate and/or the milk of lime used for its preparation by reacting milk of lime with carbon dioxide, and/or at least one of the calcium-containing preliminary products used for the preparation of the milk of lime before, during and/or after this reaction with a bleaching agent which comprises at least one compound of the formula (I): where the variables have the following meanings: and where variables, if a mixture of compounds is used and/or r=2 or 3, are chosen independently of one another for each individual compound and/or for each [(CR 1 R 2 )SO p M (1/q) ] group.