The invention relates to the use of polyacrylic acids which contain organic terminal groups containing sulphur, comprising at least two carbon atoms, having an average molecular weight M.sub.w of 5 000-30 000 g/mol and which are at least partially neutralized by a base which is selected from the group of alkali hydroxides and ammonia as auxiliary agents for wet grinding of calcium carbonate. The invention also relates to fine particle aqueous suspensions of calcium carbonate which are produced by wet grinding of calcium carbonate in the presence of said polyacrylic acids.