Interactions between stainless steels and sulphur anions in liquor mixtures typical of kraft pulp digesting

Interactions of certain stainless steels (UNS S30400, S31603 S32205, S32304, hard chromium plated S31603 as well as hard chromium plated S32205) and sulphur anions in concentrations typical of kraft liquors were investigated using wave length dispersive X‐ray fluorescence (WDXRF) and contact electric resistance (CER) techniques. Ion chromatoghraphy (IC), ion selective electrodes (ISE) and ABC titration were applied in the determining the behaviour of the sulphur anions. Hydroxide content was found to correlate linearly with the adhesion of sulphur onto steel. Impact of sulphide was evident, but nonlinear. Effect of other anions and temperature was less significant. The adhesion increased in the following order: S32304, S32205, S30400 and S31603. Film forming on S30400 possessed highest resistance properties. Hard chromium plated steels appeared to be chemically inert. For the solution, real/analysed concentrations of sulphide was less than the weighted concentrations. Thiosulphate had a tendency to convert into sulphite.